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General Discussions => The Lab => Topic started by: Mbira on March 28, 2005, 06:14:28 PM

Title: Transformer lists for projects.
Post by: Mbira on March 28, 2005, 06:14:28 PM
Hello,
I am starting this thread as a (hopefully) meta contribution.  This is a result of my own ongoing confusion as to what transformers I can use with what projects.  This is to help me when I come across a big stack of iron that I don't know what to do with.  I would like to list each major project we are doing with the transformers that are used for the job.  options will be seperated by a semi-colon ";"    

So to start:

LA2A:

Input:   Jensen JT-11-P1; Jensen JT-11-P;
UTC  A-10; A-12; A-16; A-17; A-18; A-19; A-24 (wired backwards); A26 (wired backwards);HA100X; HA-100; HA-101; HA-101X; HA-104; HA-105; HA-106; HA-107; HA-127; LS-10; LS-10X; LS-12; LS-12X; LS-26;
Sowter 4383;
Triad:  HS-8; HS-23; HS-25; HS-15; HS-27; HS-28;
Stancor: A-4351, A-4352, A-4726, A-4408
Peerless: K-054-Q; K-063-A; G-323-Q; K-281-Q; G-252-Q;
Thordarson: 25A58; 20A31; 20A08;
Kenyon: K-200; K-201; K-203; K-204; K-205; K-300; K-302; K-304;

Output: Jensen JT-10K61-1M;
UTC A-24; UTC A-25; UTC A-26; UTC-HA-113; UTC HA-114; UTC HA-133; Triad HS-50; Triad HS-52;
Peerless S-217-D; Peerless S-448-Q;
Sowter 8940;
Stancor 3250;  3315;
Thordarson 25S12; Thordarson 24S114;
 Crimson Model CT-400G

Power: Allied 6K88VG;

Pultec: (Gyraf)[/u]

Input:   Lundahl LL5402;
Jensen JT-11-P;
Quote from CJ "Any 600:600, 20-20khz, +15 dbm x-former will work.
Too many to list."

Output: Lundahl LL5402
Jensen JT-10K61-1M;
UTC A-24; UTC A-25; UTC A-26; UTC-HA-113; UTC HA-114; UTC HA-133; Triad HS-50; Triad HS-52;
Peerless S-217-D; Peerless S-448-Q;
Sowter 8940;
Stancor 3250; Stancor 3315;
Thordarson 25S12; Thordarson 24S114;

Power:

G9:[/u]

Input:    OEP A262-A3E;  
Lundahl LL1528; Lundahl LL1538  

Output:  OEP A262-A2E;  Lundahl LL5402      

Power:

G1176:[/u]

Output: Lundahl LL5402; OEP

Input:   Lundahl LL1540; OEP

Power:  Digikey TE62045-ND; Digikey TE62055-ND

Green Pre:

Power: Dagnall D2035 (newark or Farnell)


312:

input:Altran C-3402-2;
Lundahl LL1538XL; LL1674 (amphous core); LL1636 (amphorus core);
Cinemag CM-75101APC ;
Jensen JT-115K-EPC;Jensen JT110K-HPC
Sowter 9820;

outputprofile 4804;
Cinemag CMOQ-2L;
Sowter 9825

Power:

Neve 1272, 1290, or 1063/73 minus EQ[/u]

mic input Marinair T1444; T1454;
St. Ives  VT22670.
Carnhill (who purchased St. Ives) VTB9045
Sowter 9145
JLM Audio 1:4 ? Two of them as a series:parallel (1:2) or parallel:parallel (1:4) pair.
Lundahl LL1538 ? Change cap on the secondary from 180pF to 390pF.
- OEP A262A3E ? Wired for series:parallel (1:3.225).
- or use half of 31267 in reverse for 1:2

line input  Marinair T1422; T1442; T1452;
St. Ives VT22671.
Carnhill VTB9046
Sowter 9165

output Marinair LO1166,
St. Ives VT23326(?).
Carnhill VTB9049 (original replacement), VTB1148 (narrow for rack mounting), or VTB1847 (PCB version w/breakout leads).
Sowter 8751 (regular size), or 9160 (narrow version for 1RU cases).
- JLM Audio 1:1:1DC ? Does not require zobel network of 1.5k & .01uF or 600 ohm load on the secondary.
Title: Transformer lists for projects.
Post by: CJ on March 28, 2005, 06:48:11 PM
Cool idea!
You should mention that the Pultec is the Gyraff ver. w/o the innerstage x-former.

Outputs for the LA2a and Pultec could also be Triad HS-50, Triad HS-52, Peerless S-217-D, Peerless S-448-Q, UTC A-25, UTC A-26, UTC-HA-113, UTC HA-114,  UTC HA-133, Sowter 8940, Stancor 3250, Stancor 3315, Thordarson 25S12, Thordarson 24S114,


theres a ton more Sowters Jensens and Lundahls, but getting lazy.
Title: Transformer lists for projects.
Post by: Mbira on March 28, 2005, 07:19:46 PM
Thanks CJ-edited.

Keep 'em comin' folks.
Title: Transformer lists for projects.
Post by: Bluzzi on March 28, 2005, 07:22:02 PM
Also Sowter web site has the 4383 listed as the input for the LA2A.

Thanks CJ for passing on that knowledge.

Jim
Title: Transformer lists for projects.
Post by: asm on March 28, 2005, 07:22:18 PM
what about the api 312? profile 4840 on output and input cinemag...errr... dont know the number off the top of my head.
Title: Transformer lists for projects.
Post by: Bluzzi on March 28, 2005, 07:25:09 PM
Also in case you didn't notice the Allied 227-0113 is Allied 6K88VG (please no offence if you did). Just one is a P/N the other a catalog number. Both numbers will get you the same item.

Jim
Title: Transformer lists for projects.
Post by: Mbira on March 28, 2005, 07:29:53 PM
edited...No offence taken.  Many (most) of these projects, I havn't done, so I'm just collecting the info and posting it...

Joel
Title: Transformer lists for projects.
Post by: Bluzzi on March 28, 2005, 07:37:47 PM
Mbira, great idea. I am building (at least getting the parts) an LA2A.

The trannies are of course the most expensive (

Having list of equivalents Transformers is a great idea since they are the most expensive part of the unit (or ather projects I'm sure). (exception is the Power Transformer which is cheap).

Jim
Title: EXCELLENT!!!!!!!!
Post by: ToobieSnack on March 28, 2005, 07:39:55 PM
THANKS ........ GREAT IDEA
EXTREMELY HELPFUL

now lets go saturate evilbay with bids...lol

thanks
TS
Title: Transformer lists for projects.
Post by: Bluzzi on March 28, 2005, 07:41:14 PM
So you are the one that bid more than 280.00 for 2 U-24 eh?

Jim
Title: Transformer lists for projects.
Post by: daArry on March 28, 2005, 07:41:23 PM
indeed, great thread for future ref... :thumb:

thanks for the knowledge u lovely people u  :wink:
Title: Transformer lists for projects.
Post by: Mbira on March 29, 2005, 01:14:18 PM
Any other subs or projects that should be listed...Keep em coming.

 :guinness:
Title: Transformer lists for projects.
Post by: soundguy on March 29, 2005, 01:46:07 PM
the jensen 110K will also work with a 312.  I used a pair in a 312 circuit for a while, defintely works, allows for a little more gain from the opamp with a lower turns ratio than the 115.

dave
Title: Transformer lists for projects.
Post by: rafafredd on March 29, 2005, 04:57:43 PM
You should list G9 input as Lundahl LL1538, as the LL1528 is an old version, not in the market anymore...
Title: Transformer lists for projects.
Post by: ddt on March 29, 2005, 05:11:09 PM
What about Sowter 9820 for the 312 input (isn't that based on the one CJ dissected by the way?)

And shouldn't the output be 4804? ;) (Sowter 9825)

Dan
Title: Transformer lists for projects.
Post by: CJ on March 29, 2005, 05:46:27 PM
Input iron for LA2a:

UTC: A-12, HA-100, HA-101, HA-101X, , A-24, A26 (last two wired backwards), LS-10, LS-10X, LS-12, LS-12X, LS-26, HA-104, HA-105, HA-106, HA-107, HA-127, A-16, A-17, A-18, A-19

Triad:

HS-8, HS-23, HS-25, HS-15, HS-27, HS-28

Peerless:

K-054-Q, K-063-A, G-323-Q, K-281-Q, G-252-Q

Stancor:

A-4351, A-4352, A-4726, A-4408

Thordarson:

25A58, 20A31, 20A08

Kenyon:

K-200, K-201, K-203, K-204, K-205, K-300, K-302, K-304

Input iron for Pultec:

Any 600:600, 20-20khz, +15 dbm x-former will work.
Too many to list.
Title: Transformer lists for projects.
Post by: Mbira on March 29, 2005, 07:03:46 PM
Thanks guys-Thanks CJ!  I knew this would end up being a long list, but I think this is good for me and other newbees to see the wide possibilities on these projects.  

rafafredd-I added the Lundahl.  I'll also keep the old model, in case someone has one laying around and doesn't know what to do with it.

Joel

 :guinness:
Title: Transformer lists for projects.
Post by: pmroz on March 29, 2005, 11:57:54 PM
.

asm, Profile 4804  is correct for api312 output. (not 4840).
Also Cinemag CMI-8PCCA (1:8) is an option for 312 input.

CJ dissected a 4804 at vacuumbrain... did he do a Sowter too?

Didn't see any JLMs? maybe i missed it on page 1.
Someone familiar with those models?
Title: Transformer lists for projects.
Post by: Mbira on March 30, 2005, 04:02:25 PM
-updated-
 :guinness:
Title: Transformer lists for projects.
Post by: Greg on March 30, 2005, 04:24:57 PM
As Soundguy suggested, add the Jensen JT110K-HPC to the list of input trannies for the 312. I have these in a pair of mine.
Title: Transformer lists for projects.
Post by: Mbira on March 30, 2005, 04:59:09 PM
Got it-I was too lazy to see if those were input or output iron.

Joel
Title: Transformer lists for projects.
Post by: Family Hoof on March 30, 2005, 10:23:34 PM
Great thread! I love seeing this kind of organization.

Shouldn't we list the turns ratios/secondary loading conditions for each application to assist in wiring and finding even more substitutes?

Since many people have built them, allow me to add...

Neve Class A preamp (1272, 1290, or 1063/73 minus EQ)

mic input ? Secondary loaded with 4.8k (~5k) yields 1200 input when 1:2 (series:series), or 300 input (parallel:series). Originally made by Marinair, part # T1444, or T1454; and later by St. Ives, part # VT22670.
currently available substitutes:
- Carnhill (who purchased St. Ives) VTB9045
- Sowter 9145
- JLM Audio 1:4 ? Two of them as a series:parallel (1:2) or parallel:parallel (1:4) pair.
- Lundahl LL1538 ? Change cap on the secondary from 180pF to 390pF.
- OEP A262A3E ? Wired for series:parallel (1:3.225).
- or use half of 31267 in reverse for 1:2

line input ? Wire series:parallel (4:1) for 10k input. Neve part # 31267. Originally made by Marinair, part # T1422, T1442, or T1452; and later by St. Ives, part # VT22671.
currently available substitutes:
- Carnhill VTB9046
- Sowter 9165

line output - DC gapped, series:series (1:1.5) for 600 ohm output. Neve part # LO1166. Originally made by Marinair, part # ?, and later by St. Ives, part # VT23326(?).
currently available substitutes:
- Carnhill VTB9049 (original replacement), VTB1148 (narrow for rack mounting), or VTB1847 (PCB version w/breakout leads).
- Sowter 8751 (regular size), or 9160 (narrow version for 1RU cases). Both available with leads or solder tabs.
- JLM Audio 1:1:1DC ? Does not require zobel network of 1.5k & .01uF or 600 ohm load on the secondary. Fits in 1RU with at least 38mm internal height.
- Lynx Audio AT600/600-G

Please correct me if this is: a) too detailed, b) has errors, c) missing any info.
Title: Transformer lists for projects.
Post by: Mbira on March 30, 2005, 11:42:03 PM
Family Hoof,
Thanks for the work.  I have added the info to the first thread.   I was hoping to keep things in this thread to the specific format of my first post.  I think you're right that your suggestestion of listing the turns ratios/secondary loading conditions for each application is a good one-maybe we could start another thread with that info easilly accessable.  I just wanted to have this be one place where you could look at a list and see lots of different iron options...

That said, I don't own this thread or anything.
 :guinness:

Joel
Title: Transformer lists for projects.
Post by: nacho459 on March 31, 2005, 06:32:46 AM
I know I ended up using the same Jensen JT-11-P and JT-10K61-1M transformers on both my LA-2A and G-Pultecs.
Title: Transformer lists for projects.
Post by: asm on March 31, 2005, 09:49:06 PM
what about the transformer for the MXL 2001 mic with Royer mod (5840 tube).

i know people are using a jensen trans in it, i'll try to find out which model, can you use anything else?

t
Title: Transformer lists for projects.
Post by: Chuck78 on March 31, 2005, 10:52:19 PM
Should this end up in the Meta when finished???
Title: Transformer lists for projects.
Post by: clintrubber on April 01, 2005, 03:21:56 AM
This is a great initiative, thanks all !

Additional suggestions:

W.r.t. the 312, there's at least one API-channel known to man that uses two OEPs (from a DIY-brother from Spain) and it seems to work well (with a 1731-DOA).

Also: Fabio's boards have an OEP-input possibility.

So 312-input: OEP A262A3E and 312-output: OEP A262A2E.
(anyone else having used these two for an API ? I'm going to)

Regards,

  Peter
Title: Transformer lists for projects.
Post by: Mbira on April 01, 2005, 01:11:04 PM
-edited-  

Nacho, are those input or output iron?
Title: Transformer lists for projects.
Post by: Bluzzi on April 01, 2005, 03:54:52 PM
Also I found a ref. to the Crimson Model CT-400G for the LA2A as an output transformer.

Crimson Audio Transformers
PO Box 244
Cape Girardeau, MO. 63702

(573) 334-6656 or  (800) 434-1107

I found no web site.

Jim
Title: Transformer lists for projects.
Post by: nacho459 on April 01, 2005, 04:35:41 PM
Quote from: "nacho459"
I know I ended up using the same Jensen JT-11-P and JT-10K61-1M transformers on both my LA-2A and G-Pultecs.


JT-11-P = input
JT-10K61-1M = output
Title: Transformer lists for projects.
Post by: Mbira on April 02, 2005, 12:32:18 AM
-updated-
Title: Transformer lists for projects.
Post by: Family Hoof on April 02, 2005, 12:50:25 AM
Mbira,

You should probably just put LO1166 for the N*eve output Marinair #. Sorry for not being clear. Tell the moderators: This must become a meta!
Title: Transformer lists for projects.
Post by: CJ on April 02, 2005, 03:50:31 PM
I can paste this on the x-former meta once it gets to where ever it is going.
Title: Transformer lists for projects.
Post by: Mbira on April 03, 2005, 12:29:48 AM
-updated-
Title: Transformer lists for projects.
Post by: chrissugar on April 03, 2005, 01:18:28 AM
CJ , Do you have a recomendation list for the V72, V76.

Also anyone made some experiments with transformers for the REDD47?

chrissugar
Title: Transformer lists for projects.
Post by: mike_relay on April 03, 2005, 01:37:15 PM
Quote from: "asm"
what about the transformer for the MXL 2001 mic with Royer mod (5840 tube).

i know people are using a jensen trans in it, i'll try to find out which model, can you use anything else?

t


I'd be interested in this as well.. Also the transformer for the 603 tube mod...
-mike
Title: Transformer lists for projects.
Post by: dukasound on April 04, 2005, 03:33:07 PM
Quote from: "mike_relay"
Quote from: "asm"
what about the transformer for the MXL 2001 mic with Royer mod (5840 tube).

i know people are using a jensen trans in it, i'll try to find out which model, can you use anything else?

t


I'd be interested in this as well.. Also the transformer for the 603 tube mod...
-mike

Mike transformer for Royer mod is Jensen JT-DB-E or JT-DB-EU (where is EU uncased if you have MXL, ADK, Generis with transformer case inside mic).
Title: Transformer lists for projects.
Post by: ToobieSnack on April 04, 2005, 03:52:39 PM
Hey, I'd be intereseted in knowing about the V72 and V76 iron too.
Also can someone list mic trafo's.
I need one for my RCA 74b ribbon mic and
or a tube mic like my neumann cm7156? or the graf tube mic?
thanks
TS
Title: Transformer lists for projects.
Post by: smilinfu on April 04, 2005, 04:18:44 PM
I am using the LL1578XLs and some LL1636s in my API 312s, but I really have almost no idea what I am doing :shock: .  They are 1:10 instead of the 1:5 a lot of folks use (I have not tried 1:5 so I have no comparison).  This list could get huge, as there are so many options for so many projects.

Anybody have info on the LA-3 ins and outs?
Title: Transformer lists for projects.
Post by: dukasound on April 22, 2005, 09:45:25 AM
Hi
I can find one UTC HA-108 transformer. I know some specification but for what is this transformer useful. Also where are this transformers embedded.
Thanks
Duka
Title: Transformer lists for projects.
Post by: CJ on April 25, 2005, 12:17:46 PM
I used a Jensen output, 4:1 for the V76. Nice chunk O Ni, sounds great. Input can be your favorite flavor of the month x-former for 72/76. Higher the ratio, more rolloff, except Ollie's V76 in which has 1:30 ratio but no rolloff.
cj
Title: Transformer lists for projects.
Post by: Cainester on April 25, 2005, 03:34:56 PM
What ever happened to that 2622 "hack" that was discussed?
Caine
Title: Transformer lists for projects.
Post by: CJ on April 25, 2005, 04:42:19 PM
You mean this:

(http://vacuumbrain.com/The_Lab/TA/API_2622/2622_1.jpg)
Title: Transformer lists for projects.
Post by: Cainester on April 25, 2005, 05:03:18 PM
Thats the one!  :thumb:
I'd love to have 4 or 6 of those.  Did anyone ever inquire on getting a run produced?
Title: Transformer lists for projects.
Post by: Family Hoof on April 26, 2005, 12:12:24 AM
I added the Lynx Audio AT600/600-G under the list of N*eve gapped output transformers.
Title: Transformer lists for projects.
Post by: Bluzzi on April 26, 2005, 12:52:15 AM
OK now you have my curiosity peeked! What is that thing CJ??

What is a "gapped" transformer and what is its function?

Jim
Title: Transformer lists for projects.
Post by: CJ on April 26, 2005, 03:02:52 AM
It's just a normal transformer that has the lams all facing the same direction instead of interwoven. An E-I core is a two piece lam that has one piece shaped like an E, and another piece which is just a rectangle. In a gapped transformer, the rectangle like lams are all stacked together so the form a brick like shape. This brick is layed across the E lams in a gapped transformer. In a non gapped core, one E lam will go one way, then the next E lam will be stacked opposite it's neighboring lam, alternating back and forth across the entire core.

In a gapped transformer, there may or may not be a piece of insulation in between the lams. A typical gap is made out of something known in the x-former bussiness as Kraftpaper, sometimes abbreviated KP. It looks just like the old brown wax paper they used to wrap your lunch in, if you are that old.

So you might see spmething like Gap: .002 KP, which means a piece of Kraftpaper that is .002 inches thick (or thin I should say).

This gap between the lams does two things.

1) It keeps the core material from becoming magnetized by any DC in the primary.

2) It keeps the transformer from saturating.

It does this by interupting the magnetic path of the core.
A transformer saturates when the core is no longer able to handle any more magnetic flux. This flux is the result of an ac signal in the coil which surrounds the core. As you increase the voltage, and thus current in a coil, the magnetic lines of flux also increase. The amount of flux in a given area is called flux density. Transformer designers usually have there favorite constants of flux density for different alloys. They usually express this constant as kilogauss per kilogram. Certain metals are able to handle different amounts of flux density, or kilogauss per kilogram of core material. M6, or grain oriented silicon steel, can handle a lot more flux density than 50/50 (an insiders slang for 49% Nickel core) and Superperm, (80% Nickel). That is why it is used in situations that  produce a lot of flux, such as output transformers and power transformers.

A coil without a core, (air core transformer) , will have a very hard time linking the primary signal with the secondary signal, because the magnetic lines of flux tend to radiate into space, where they can do little good as far as inducing a voltage in the adjoining winding in the coil. The transformer core acts to pull these lines of flux inward, back from outer space, where they can be used to link the signals between coils. The more "permeability" a core has, more concentrated the flux becomes for a given signal, or the easier time it will have pulling the flux lines in where they can do work.

    The Nickel core transformers will concentrate the flux produced by a coil in a lot more efficient way. A superperm core, for example, will only need to be roughly 1/5 th the size and weight of a M6 core to produce the same flux density. The problem is, since it is so good at concentrating flux, it can become overloaded, or saturated much easier than an M6 core. Think of it as an amplifier. The more gain an amp has, the quicker it will become overloaded. A Marshall stack will crunch out before a Fender will. So, a superperm core will overload quicker than a regular steel core.

In a case where you have a very weak signal that you want to get off the noise floor as soon as possible, (mic pre), you want a core material that will give you a lot of flux density for a minimum of signal. This is why you will find the best mic input transformers made out of 80% Nickel. Since mic signals are relatively weak compared to line level,  speaker level and power level signals, you rarely have to worry about overloading the core, unless it is made out of very small lams, in which case, you might actually want the core to become slightly saturated. This is where the term "colored sound" or the phrase "the sound is in the iron" comes from. Some people actually want to impart a little alteration to the original signal in order to get a different tone.

So the bottom line with a gapped transformer is that it will sacrafice some permeability for an increase in it's abillity to handle dc in the primary. It's a tradeoff. You will need a few more tuns of wire in the coil to get the same flux density, but you can hit the transformer with higher levels before the core will cause distortion in the lower frequenciy ranges of the audio signal. If you are still confused, ask somebody who actually knows how to explain this rather hard to understand thing called a transformer.
 :razz:
Title: UTC
Post by: dukasound on April 26, 2005, 04:03:49 AM
Hi Chris
What do you think about UTC HA-108 transformer and where I can put this
transformer?
Duka
Title: Transformer lists for projects.
Post by: CJ on April 26, 2005, 12:55:30 PM
That would be great in a Pultec EQP or MEQ as an input to the passive filter section. Handles 20 db, great for today's levels.

Or anyplace else that uses a 600:600.

Or, you could try a trick I just heard about from my old timer x-former buddy:

 Since you have a 50 ohm tap on the pri, use it as a 50:600 ohm step up. You turn a 1:1 xfmr into about a 1:3.5 step up, which could be used to drive a Neve input from a mic, if the mic did not mind the low impedance. Or maybe even a line in to a Neve if you used it in reverse, or maybe ( I haven't tried this yet) a mic to grid if it has enough turns to provide the inductance needed for the tube grid.

Or, use it in reverse as a step down transformer. The core is big enough for a parafeed output stage in a tube pre, Pultec, or LA2. It even handles 0.5 ma dc, so maybe even get away with a direct coupled 12AX7a output to line, but you would probably run into saturation at higher levels, which may or may not be a nice thing, depending on your recording philosphy.

cj
Title: Transformer lists for projects.
Post by: dukasound on April 26, 2005, 02:24:26 PM
Thanks Chris :thumb:
Title: Transformer lists for projects.
Post by: Bluzzi on April 27, 2005, 08:58:11 AM
CJ - Now that is an AMSWER ! Wholly s---t!

I don't understand everything (or anything maybe) but sometimes if I reread and reread sothing I don't understand, eventually one day my brain just seems to get it.

The trouble is now you got me interested in Transformers! Will this curiosity ever end? I just wanted to play music, then I started to record music and got into recording gear and techniques. I wired an entire studio more than once, I didn't want to but because I know my mixing board better than my tech, ended up repairing the 5 out of 7 strips that were not functioning properly and its given me confidence to repair the last 2 which seem to be more dificcult to fix. Now I am gathering parts for a few LA2As.

One of these days I'll have to get back to songwriting and playing! I envy my friends that only play music! I was born with this insatiable appetite for learning things on my own. I love it!

Too many things to learn and do and too little time.

8-)

Thanks CJ for taking the time to answer a question with a very precise response.

Jim
Title: Transformer lists for projects.
Post by: CJ on April 27, 2005, 01:11:22 PM
Well, I haven't actually tried the things I mentioned for the HA-108, so...

But if there is enough wire on that thing, he might luck out.

I usually rely on PRR to staighten out my posts, but I haven't seen the ol boy around for a while.

If you are putting together a home studio with cool gear, you probaly won't touch a musical instrument for about two or three years.

But the songs will be building up and the instrument  will seem fresh again when you get back to it. Right? I hope!
Title: Transformer lists for projects.
Post by: Bluzzi on April 27, 2005, 01:20:29 PM
Quote from: "CJ"
If you are putting together a home studio with cool gear, you probaly won't touch a musical instrument for about two or three years.

But the songs will be building up and the instrument  will seem fresh again when you get back to it. Right? I hope!


I had a studio built and running a while ago BK BB (....before kids...before business), so much of it was already there. But I had to buy new board, monitors, mikes etc. Main work is wiring and getting the board to work 100% (almost there). I'm a bit anal about things running 100% (or near). Once I start playing and recording I don't want the equipment to get in the way.

Jim
Title: Transformer lists for projects.
Post by: CJ on April 27, 2005, 01:48:48 PM
well, I hope you pop in every now and again once you get all your stuff straight.
I will probably disappear for a while so I can try out all my new toys together.

Speaking of disappear, where has that Bluebird character  gone?

World tour or something?
Title: Transformer lists for projects.
Post by: Bluzzi on April 27, 2005, 02:02:26 PM
Nah! I'm here for a long time. If the LA2As is a positive experience (no reason other than fear of the unknown not to be) I want to build more!
1176, SSL comp and then maybe some preamps. More LA2As? I really love tube gear, as a long time ago thats what I built and find it easier in many ways to Solid State circuits (not always). Mostly because of the point to point. I have yet to solder anything on a copper clad board!

Hey I just bought a Weller soldering station! I bought a crappo clone of it on Friday and blew it de-soldering my A-24 transformers (need to get them cleaned up). The Weller is almost double the price! Hope it lasts as long as my friend's Weller WTCPT (that I have been borrowing for the last 5 years!). I have a Radio Shack multimeter but no oscilloscope yet.

Sorry for getting so off topic here.

CJ, do you really wind your own transformers?

Jim
Title: Transformer lists for projects.
Post by: CJ on April 27, 2005, 03:08:54 PM
I have wound a few on some crude equipmemt. I want to get a real winding machine so I can go to town and wind a few of the xfmr's I have dissected.

Next up will be a Peerless S-217-D, if I can just get Mike at Magnequest to answer his emails. I send a message, and he answers it. Then nothing for a month. Then another messager, he answers it. Then another month! :mad:

He still has the 12L lams for me, but won't tell me total price and mailing address for payment.

Winding xfmr's is rewarding, but probably as expensive as buying one, as the factories have all their debt paid (competive profit margin) , and are all set up for processing and mechanical, which is really the biggest pain as far as transformes are concerned (vacuum chambers, dry out ovens, varnish and wax, core brackets, terminal strips,  mu cans, etc).

But it would be nice to have a set up where you could say: "OK, I think I want to build an API preamp. Don't have any iron, money, or time for evilbay hassles,so I guess I'll just wind my own."
 :thumb:

Be careful with those UTC terminals. The wires from inside the transformer are actually stuffed into those terminals, sometimes you can see the breakout leads wrapped around the outside. So if you de-solder them, the wire might work it's way loose, but usually it is well setteled as it has not been disturbed for years. Get your self a solder sucker and some copper braid (solder wick) for cleaning up those terminals. It's always a good idea to resolder vintage transformer terminals as they can become pretty groody from all those years, plus, the solder was pretty nasty back than as far as flux and rosin is concerned.
Title: Transformer lists for projects.
Post by: Bluzzi on April 27, 2005, 03:13:56 PM
CJ - What does a winding machine look like. There are some on eBay but I have a feeling they are limited.

Is it something that is huge or small in size. Could it be built? The friend that I am building an LA2A for has a huge machine shop and I have open access. He is amazing at drawing and inventiing/designing mechanical apparatus. (plural? appariti?) Maybe I can help.

Jim
Title: Transformer lists for projects.
Post by: CJ on April 27, 2005, 03:28:19 PM
See the V72 DIY thread. All I did was put a hand drill in a vise. A mandrel ( the thing that holds the coil bobbin or paper former to which the wire is wound upon) was made from a 1/4 inch bolt and some masking tape. A wire tensioner can be made with a clothes pin and some type of foam, maybe that black stuff that IC's are stuck to would work, or just plain cloth of some type. The biggest problem is materials. Unless you work for a company that does electronic oriented stuff, getting lamination samples from Mag Metals might be tough. Then there's the magnet wire. Very expensive unless you can find rolls at a surplus store.

Winding machines come in all sorts of price ranges, from Chinese made hand cranked jobbies that you see on ebay for 20 bucks, all the way up to 10,000 dollar computerized multiple machines ( they might wind ten coils at a time in a high output shop), or even a 100,000 dollar machine that will do everything but re-fill your coffee cup while you supervise it. Were talkin a machine that will pick up a bobbin, mount it on the mandrel, spin the wire on, tape the leads, and spit it out the other end, all in a matter of seconds.

A friend of mine built his own computerized machine which uses a 1 hp dc General Electric surplus motor. It has a very accurate stepper motor to control the pitch, (the spacing between turns). Sometimes you want a little space between turns in order to control leakage inductance and capacitance.  So a DIY machine of sophisicated quality can be done if you have the resources.

cj
Title: Transformer lists for projects.
Post by: andre tchmil on April 27, 2005, 03:31:27 PM
I have a UTC A-21 . 500ohm to 500ohm. 30-30kc , 500v.hipot.
Max level +15dbm.

Anyone knows what this means , and where I can use this one for ?

Also I have tons of Lundhal LL1524      ?????
Title: Transformer lists for projects.
Post by: CJ on April 27, 2005, 03:40:33 PM
Hmmm, I only see about 28 ohms pri DCR, compared to the A-20, which has about 60. So your inductances might not be up to snuff for something like I mentioned in the answer to Dukasound.

Do you have an inductance meter?
Title: Transformer lists for projects.
Post by: Bluzzi on April 27, 2005, 03:51:54 PM
So it looks like the Lamination is the hardest to source? I can try and find sources for you (I use to be a buyer in the military electronics industry).

Let me know.

Also CJ, I got my A-24s in and I am in the process of cleaning the terminals.

I got 4. One of them has the UTC A-24 riveted plate and is a dark grey. The others have no designation plate but seem to have the same numbers ink-stamped which seem to be drawing numbers. Those are same as on the dark grey one.

The resistance on the terminals are very close to each other for component to component and they are exactly the same size etc.
I have no continuety on some of the terminals. Is that normal? It would seem so as they are all consistent with that.

It looks like they are all A-24s but why some are not marked? Made for third party maybe?

Jim
Title: Transformer lists for projects.
Post by: CJ on April 27, 2005, 04:19:35 PM
Different vintage UTC's will have differen resistances.

Here is a site with some xfmr info. Click on the logos.

http://www.vacuumbrain.com/docs/iron.html
Title: Transformer lists for projects.
Post by: ToobieSnack on May 18, 2005, 05:32:02 PM
I would like to see a list of ribbon mic trafo's I know of the sowter and lundahl's what about the cinemag and others ...not so well known...i need cheap....:grin: for experimental purposes..even trafo used backwards or something....

Also****
what would be suitable I/O and power trafo's for the:
 Federal AM864/u
specs are 600/10,000...10,000/600 ....would these be similar to la2a iron listed in here ?
there seems to be a lot of projects that require 600/10,000 10,000/600.
what seperates these ?trafo loading specs?
 
thanks
ts
Title: Transformer lists for projects.
Post by: rafafredd on May 18, 2005, 07:47:59 PM
You need "balanced" transformers for the am864. It´s a push pull circuit, like all other vari mu comps.
Title: Transformer lists for projects.
Post by: fantomas on July 09, 2005, 03:18:56 PM
are the neutrik useful for something?
which models?
Title: Transformer lists for projects.
Post by: anna loog on July 16, 2005, 01:39:25 PM
(http://www.dawusers.com/pa/malotky3_0045.jpg)

(http://www.dawusers.com/pa/v282a_schematic.jpg)

here  is a nice tranformer used as output trafo  for v282a
Title: Transformer lists for projects.
Post by: JW on July 16, 2005, 10:37:25 PM
You know what would be pure gold, is a couple options for output transformers for the yamaha PM1000.

1:2 would be the best.

Anybody?
Title: Transformer lists for projects.
Post by: peterc on July 17, 2005, 06:42:09 AM
Quote
are the neutrik useful for something? which models?


I've used these very successfully, the good ones are the Mu-Metal shielded NTM 1 (mic) & NTL 4 (line).

For data, go to www.neutrik.com , then switch to the Neutrik USA site, then search for "ntm" or "ntl".

Regards
Peter
Title: Transformer lists for projects.
Post by: Sammas on July 17, 2005, 07:25:34 AM
Don't forget Joe's stuff too!

JLM 1:4 input tranny
JLM 1:1:1 DC Gapped Output transformer

Both will work in the 312 i believe...
Title: Transformer lists for projects.
Post by: Jonkan on July 17, 2005, 09:18:12 AM
will the JLM 1:1:1 DC Gapped Output transformer work in a 1272 circuit?
/Jonas
Title: Transformer lists for projects.
Post by: clintrubber on July 17, 2005, 09:42:06 AM
Quote
will the JLM 1:1:1 DC Gapped Output transformer work in a 1272 circuit?

Yes, read more here:
http://www.jlmaudio.com/JLMDI.htm
Anyone used these already for a BA283... ? How does it compare in sound with the other types of TX ?
Title: Transformer lists for projects.
Post by: smallbutfine on July 22, 2005, 03:43:04 PM
peterc wrote
Quote
I've used these very successfully, the good ones are the Mu-Metal shielded NTM 1 (mic) & NTL 4 (line).


Peter, in which projects did you use them?

Kind regards

Martin
Title: Transformer lists for projects.
Post by: peterc on July 22, 2005, 04:35:49 PM
I used an NTM 4 in a Neve pre from Joe Malone's page, long gone to a friend.

Used the NTL 1's to isolate monitors to get rid of a problematic hum problem, & I've seen them used for a DI, tho' I never actually heard that unit.

I also used an NTM 4 in a Focusrong mic pre which sounded good on the bench but never made it out of my projects box.

Also used the NTM 4 in a Neve 283 mic pre project.

Peter
Title: Transformer lists for projects.
Post by: smallbutfine on July 22, 2005, 11:32:56 PM
Quote
Focusrong
:shock:
LOL :wink:
Good one!

Asking because they are highly available in europe (conrad) but they are not cheap really...but that fits a neve project.... :wink:

Thanks alot,

Martin
Title: Transformer lists for projects.
Post by: dissonantstring on August 13, 2005, 05:54:25 PM
hi,
i have a question about the G1176 posted power transformer.
in the intial post of this thread it lists: Digikey TE62045-ND; Digikey TE62055-ND
these are both 2X22V transformers and in the "All things G1176" thread
jakob says that 2X22V is too little, it must be 2X24V.
has anyone tried the listed 2X22V transformers (and do they work or
have you had any problems with them)?
any comments would be greatly appreciated.
-grant
Title: Other suggestions for API style mic-pre . . .
Post by: strangeandbouncy on August 13, 2005, 07:47:29 PM
Hi there,
   
    fwiw, I've just made 3 pre's based on API 312 using ex-Neve Willesden 10014/Belclere20014(Same, I think) 1:5+5 wired with only 1 sec winding, and 1 with Marinaire 31267, wired backward and only 1 winding each on pri/sec as suggested by JLM Auido for 1272.  Un-balanced output, with no output trannies, just an electrolytic cap, since cable runs are short, and my un-balanced Helioses don't seem to suffer from being un-balanced!
   Both sound amazing, with an overall similarity. Marinaire version is slightly cleaner top end, and a tiny bit more detailed. Not much in it. Maybe it's an unfair comparison since the ratios are different, so op-amp is working harder at same gain. I also have no idea if any Zobel(?) network is required to correct any ringing. I certainly can't hear any . . .
   Contrary to popular belief, I firmly believe that it is not just the "iron" that counts in these, since everybody's overiding impression(including mine!) is that they sound like API's, and not Neves . . . maybe the circuit topolgy makes it sound like API? Can't wait to try some other Op-amps(not just original API and Fabio;s [email protected]@[email protected]'s( not much between them imho), and see if I/anyone can hear any difference. I have a 2151 copy (5534 with Transistor output stage lashed on) to try as an alternative. Most people can't tell the difference between this and a 2520 in a 553! Confusing . . . .
    I also tried sowter 150:150:150:150(I've forgotten no.) as output tranny. I tried 600:600, and 150:600. Also 150:150, single winding, and parrallel. They sounded great in every combination, but slightly different. i prefered 600:600, but this was not as good as unbalanced with no tranny. Sadly, i haven;t got a spare 4804/2503, or Sowter equivalent to hand to compare. Also, I don't really need any more gain for my particular application( Drums/GtrAmp/BassAmp/DI/Hot valve mic)

   Goddamn, these Puppies Rock! Just found 3 more trannies to use . . . 2 more Marinaire, and one more Willesden. I know someone who has HUNDREDS of (i.c.) ex-Neve cards, with loadsa similar trannies(Belclere/Willesden) i know they ain't exactly flavour of the month, but they sound pretty damned good to me!


      ANdyP

     p.s. - I have been getting some instability problems with [email protected]@[email protected]'s. occasional RF, and oscillation. CAn anyone suggest a cure?[/img]
Title: Transformer lists for projects.
Post by: JustinS on August 14, 2005, 05:45:39 PM
Man Andy,

You have been a busy boy!  Interesting experiment to do as well - a "Neve" API...  :grin:

Justin
Title: Transformer lists for projects.
Post by: martthie_08 on September 01, 2005, 08:20:37 PM
can anybody suggest a vintage output transformer for the gyraf version of the pultec eqp1 tube eq (with srpp gain stage)?

On the schematics on jacob's site, there is a 2:1 lundahl suggested, but I would like to get something old to go with the UTC A20, that I would like to use for the input.

Is there a different UTC model that will work for this specific output or anything from triad or anything from stancor? Thanks!!
Title: mic output transformers
Post by: sbranco on September 02, 2005, 10:12:36 AM
It would be nice as someone mentioned earlier for this thread to include transformer options for mic bodies.

After listening to Duka's four mic's via his posted mp3 and then listening to the shootout on "Cinemag's website between a Neumann and their 2461NiCo transformer in identical mics, it convinced me to build two G7's with different transformers rather than two different mics.

I was thinking about building a G7 and C800g. However, in Duka's mp3, I preferred the G7 and didn't think the C800g was that different. In the Cinemag shootout, the transformer seemed to make more of a difference than the totally different mics in Duka's mp3.

So I think I am going to build two G7's. One with a Lundahl 1538XL and one with the Cinemag 2461NiCo. It seems to me that the different transformers will provide the different flavors I am looking for better than a totally different mic schemo.

The Lundahl 1538XL is a little larger than the 1538 but has more headroom and wider frequency response and it costs only a few dollars more. Not sure if it was available when Gyraf designed the G7.

Also, although Royer used a direct box type transformer in his mod, Cinemag just recommended to use a humbucking 2480 tranformer.

It seems Cinemag, Lundahl, Sowter and Jensen are the only widely available transformers suitable for the mic output job. And by widely available I don't mean DigiKey. You have to go to their website and either order direct or go to their local distributor.

Truthfully, I haven't even seen many mic output transformer models mentioned on the board. Maybe this should be a post unto itself.

For example, someone mentioned a Sowter 4935 I think as good for mics but I couldn't find that model on the US distributors website.

The manufacturers websites do have precise measurements so you can tell if the transformer will fit in your mic body. And the meta on transformers is good but not much there on mic output transformers.

There are some pretty in depth discussions about tubes for mics and capsules for mics but considering the effect of transformers on the sound, I think more discussion of mic output transformers would be good.

Maybe this is because tubes are cheaper to compare by trial and error but capsules certainly are not.

Admittedly, there has been some good discussion of matching transformer outputs and the mic circuits (which I still have to figure out) but the circuits seem to be pretty forgiving regarding whether you select a 5:1 or a 10:1 turns ratio.

Finally, althought I am calling these Mic Output Transformers, only one website I looked at called them that. Lundahl for example refers to the 1538 and 1538XL as Mic Input Transformers. OK turn them around they become output transformers but is that always true and why don't they say that?

And the Jensen recommended by Royer is listed as a DI box transformer. Even the Jensen website recommends a different one of their transformers for tube mic use (which I assume would include the Royer mod) so why in the world did Royer choose a DI box transformer? Cost? doesnt' seem so, Why not a mic input transformer like the mfg's themselves recommend?

I hope this post will prompt some discussion that will benefit others pondering the same things I have been struggling with. This is a fairly confusing area. I have found the mfg's to be pretty helpful regarding their products.
Title: Transformer lists for projects.
Post by: hejsan on January 16, 2006, 06:12:15 PM
Quote from: "CJ"
Cool idea!
You should mention that the Pultec is the Gyraff ver. w/o the innerstage x-former.

Outputs for the LA2a and Pultec could also be Triad HS-50, Triad HS-52, Peerless S-217-D, Peerless S-448-Q, UTC A-25, UTC A-26, UTC-HA-113, UTC HA-114,  UTC HA-133, Sowter 8940, Stancor 3250, Stancor 3315, Thordarson 25S12, Thordarson 24S114,


theres a ton more Sowters Jensens and Lundahls, but getting lazy.


In case youre not lazy anymore :green: Do you know of any lundahl ins and outs for the LA2a?  I remember there was a thread where bloo and someone where studying plots of LA2a's with different transformers, including Lundahls, but the lingo in that thread was so damn streat smart I couldn't understand a thing :oops:

Are there any good lundahls then??

regards,
hej
Title: Transformer lists for projects.
Post by: ciminosound on January 17, 2006, 02:03:33 PM
Quote from: "asm"
what about the transformer for the MXL 2001 mic with Royer mod (5840 tube).

i know people are using a jensen trans in it, i'll try to find out which model, can you use anything else?

t


The JT-DB-E is a 12:1 used in reverse. You could use UTC O-1 trannys reversed if they would fit the case. Even the O-2, O-3, O-8, O-9, O-10, O-11, O-16? Reverse the input transformers for correct ratios. The output transformers would be wired normally.

http://vacuumbrain.com/docs/Sub_Docs/utc.html
Title: Transformer lists for projects.
Post by: rodabod on May 20, 2006, 01:44:33 PM
Quote from: "clintrubber"

W.r.t. the 312, there's at least one API-channel known to man that uses two OEPs (from a DIY-brother from Spain) and it seems to work well (with a 1731-DOA).


So 312-input: OEP A262A3E and 312-output: OEP A262A2E.
(anyone else having used these two for an API ? I'm going to)


Peter, have you (or anyone else) tried using the OEP A262A2E as an output transformer?

I was wondering if it would saturate (I can't tell if it is only for mic inputs or not...)

Thanks,

Roddy
Title: Transformer lists for projects.
Post by: cjs2k on May 29, 2006, 09:49:04 PM
For the LA-2A Power transformer, I'm using the Triad r-4a. They show up occasionally on Ebay.
Title: Transformer lists for projects.
Post by: laiben on December 01, 2006, 10:47:53 AM
I find this thread is very useful, don't want it to die!

Thanks guys!
Title: Re: Transformer lists for projects.
Post by: Gulistan on November 30, 2009, 12:31:11 PM
hello,

do you know "Vigortronix" transformers...
found at Farnell http://export.farnell.com/jsp/search/browse.jsp?N=500006+1001637&Ntk=gensearch_001&Ntt=vigortronix&Ntx=mode+matchallpartial (http://export.farnell.com/jsp/search/browse.jsp?N=500006+1001637&Ntk=gensearch_001&Ntt=vigortronix&Ntx=mode+matchallpartial)

http://www.vigortronix.com/subcategory.aspx?catid=124 (http://www.vigortronix.com/subcategory.aspx?catid=124)
specs are very close to OEP A262Axx serie
but what about the sound ?
Title: Re: Transformer lists for projects.
Post by: creal on January 28, 2012, 10:49:38 AM
Hi All,

I looking for a input transformer for my LA2A P2P. It's the only missing part for finish the project.
i found a UTC A-11 on evilbay, so i like to know if it's suitable  for the LA2A
Here is the spec :rated at: 500/200/50 ohms primary, with secondaries of 50k ohms PP. 20-20kc frequency response. +5dbm

if someone here have a UTC A-10 to sell,  PM me

Best
Cyril
Title: Re: Transformer lists for projects.
Post by: CJ on December 13, 2014, 05:28:22 PM
found this lost of transformer usage while wandering around the net>

http://www.diyrecordingequipment.com/blogs/news/15851752-work-in-progress-the-ultimate-audio-transformer-list
Title: Re: Transformer lists for projects.
Post by: bancho on February 11, 2015, 05:13:43 PM
On the first page of this thread there are in/out tx options for LA2A... it says the A-24 and A-26 can be used also for input if wired backwards. Could be A-10 and LS-10 also used for output if wired backwards?
Did anyone use A-24/26 for input? Results?
Title: Re: Transformer lists for projects.
Post by: EmRR on February 12, 2015, 10:24:08 AM
A-10/LS-10 I wouldn't use backwards.  Higher ratio, thinner wire, larger gain drop, expensive options too. 
A-26 I wouldn't trust unless tests showed flat response when run single ended.  Many PP transformers don't look that good with single ended connection.  Might be fine, might not.  A-24 would be fine, used as input in RCA BA-100 series preamps, but with the additional shield.  LA2A, higher input levels, shield probably not necessary as with mic use. 
Title: Re: Transformer lists for projects.
Post by: Quayhog on June 23, 2015, 02:34:59 PM
Could  a UTC HA-133 wired backwards be used as ai input transformer?  The specs and pinout are the same just backwards.  I've had an old time engineer tell me it's ok and a lot of Internet experts tell me no.  I'm curious if there is anyone that has actually used one wired backwards successfully?

Title: Re: Transformer lists for projects.
Post by: EmRR on June 23, 2015, 03:25:52 PM
That would be a huge waste of an expensive output transformer that can handle B+ in its primary, which is a tough parameter to find for preamp use.    It would probably work.  You should save it for an RCA BA-2 instead. 
Title: Re: Transformer lists for projects.
Post by: Quayhog on June 23, 2015, 11:13:00 PM
Doug, it's unlikely I'd build an RCA BA-2 so I may still use the HA-133 as an input transformer.  I currently have my mic preamps covered with a quad of Grommes G5m, a Grommes GT5, and a pair of Altec 1567a. At age 63 I don't think I'll be building too much any more.

I do need to build a quality preamp for my 807 stereo amp.
Title: Re: Transformer lists for projects.
Post by: EmRR on June 23, 2015, 11:25:13 PM
Then I think it'd be in societies best interest if you sold it to someone who needs it, assuming you have no use for it as intended, and buy an A-10 or HA-100 with the proceeds.  Then you'll have the right transformer, and so will they.  A good tube output that takes DC is about the hardest thing to source these days, and it really is being wasted to reverse it, IMO.   I'm not trying to be hard on you, just pointing out that transformers like that are among the toughest things to source for certain circuits, and many of the modern 'recreations' seem to fall flat. 

Better reasons to use HA-101, or HA-105, or A-16, or A-18, or LS-12X, or LS-26.  Or I have a Kenyon P-204 that came off a Presto 88-A disc cutting amp, excellent specs.  I also have an RCA BA-3 program amp input that I should part with.  Peerless 15335, mirror the Jensen 'upgrade' suggestions, but with a 'vintage' input.   Peerless 15095 if you want some step-up and a 600 input.  Possibilities are endless.    One UTC is not bound to sound like another, not even two A-10's or A-24's that I've auditioned side by side have sounded 'the same'.  Similar, but not identical to be closer than a Thordarson substitute, etc etc etc. 

ssltech has made the point in the distant past that there's something about having 20dB step up in the input transformer ( and corresponding treble loss in the barely open gain pot) that lets you drive the amp hard which gets lost with a 1:1 like the Jensen plan.   I can only add that the LA-2 was designed in a time when much lower levels were being sent to the input of an LA-2, and that step-up is not so much needed anymore, and in fact can be a huge liability (see previous parenthesis). 
Title: Re: Transformer lists for projects.
Post by: Quayhog on June 24, 2015, 12:46:15 AM
I'm sourcing the parts to assemble an LA-2A.  My spare Ha-133 came in same acquisition as my HA-100x.  While I have an unused old stock UTC A-24, I suppose I could use the HA-133 as the output.  Early saturation is one of the deficiencies of the LA-2a. Would the larger transformer ease that deficiency?
Are there any other advantages to using one output transformer over the other?

By the way Dave, I don't feel you were hard on me. I'm still trying to get my head around transformers.  I'm a novice and still learning.
Title: Re: Transformer lists for projects.
Post by: EmRR on June 24, 2015, 12:50:10 AM
I added some bits to the previous post as you were responding.

The HA-133 backwards won't really gain you much headroom to speak of, a few dB more but all before the gain knob.  Headroom is mostly in the capabilities of the output amp.  It would be a step up used as the output (roughly 7dB more transformer headroom and better response) versus the A-24, but then it's still the more sought after transformer compared to the HA-113 which should sell somewhat less, HA-113 being less useful as a piece on the shelf, no disadvantage in the LA-2. 
Title: Re: Transformer lists for projects.
Post by: Murdock on April 25, 2016, 06:03:03 PM
It is stated that we can use the Peerless S217D as output transformer in the G-Pultec. Is that true? If so, would we have to change anything in the circuit?
Because I read somewhere that it isn't really suitable for the different output amp design...
Title: Re: Transformer lists for projects.
Post by: CJ on April 26, 2016, 01:07:58 AM
you have a 217?!!!

Title: Re: Transformer lists for projects.
Post by: Murdock on April 26, 2016, 04:47:11 AM
Hehe, no unfortunatelly not, but I'm part of the cinemag clone groupbuy... and I wanted to know if I could use them on my stereo G-Pultec. Or would it be better to use it in a p2p clone?
Title: Re: Transformer lists for projects.
Post by: kambo on June 11, 2016, 01:44:33 PM


Pultec: (Gyraf)[/u]

Input:   Lundahl LL5402;
Jensen JT-11-P;
Quote from CJ "Any 600:600, 20-20khz, +15 dbm x-former will work.
Too many to list."


would 10k:10k jensen really work on  pultec input ?




Title: Re: Transformer lists for projects.
Post by: Murdock on July 27, 2016, 06:07:55 AM
Hey, sorry for reviving this thread again, but I would really like to know, if the info on the first page (regarding the S217D in the G-Pultec) is valid.
The G-Pultec calls for a 2:1 transformer (ll5402). But the S217D isn't?
http://cinemag.biz/output/PDF/CM-S217D.pdf
http://www.bunkerofdoom.com/xfm/PEERLESS1953/Peerless_1953_08_0001.jpg
Is it possible to change the circuit somehow to use the S217D in the G-Pultec?
Title: Re: Transformer lists for projects.
Post by: MatthisD on July 27, 2016, 08:57:16 AM
Assuming the Cinemag version is identical then there is  no need to change the circuit. Connect the primaries in parallel for 3125 ohms and secondary for 600 and also the feedback winding connected to ground at one point which acts as an electrostatic shield.

If you get a chance to measure the resistance of the windings please let us know.
Title: Re: Transformer lists for projects.
Post by: Murdock on August 12, 2016, 04:21:38 PM
Hey Matthis, thanks for your reply! Sorry for my late reply, I just had the time to look into this.
Is this the right way to connect the S217D in the G-Pultec?

(https://s10.postimg.org/f03x3fm6x/S217_D_G_Pultec.png)

The numbers in the S217D diagram are just to show the corresponding Lundahl pinout.
Title: Re: Transformer lists for projects.
Post by: MatthisD on August 12, 2016, 07:38:37 PM
Yes, the resistor on the secondary might not be needed.
Title: Re: Transformer lists for projects.
Post by: Murdock on August 12, 2016, 08:47:33 PM
Thanks!
OK, I will try with and without the resistor. When I leave the resistor out, should I put a jumper in place of the resistor?
Title: Re: Transformer lists for projects.
Post by: MatthisD on August 12, 2016, 09:59:42 PM
No jumper, although you would need to be able to measure  the frequency response to see what effect that resistor has.
Title: Re: Transformer lists for projects.
Post by: dukasound on June 17, 2017, 12:43:19 PM
On first LA-2A I used Sowters, on second Jensen JT-11P for input and UTC A-24 for output. Can I use Lundahl 1:1 LL1540 on input on next project??