Transformer lists for projects.

[ciminosound]

[quote author="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[/quote]

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

 

[rodabod]

[quote author="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)
[/quote]

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

 

[cjs2k]

For the LA-2A Power transformer, I'm using the Triad r-4a. They show up occasionally on Ebay.

 

[laiben]

I find this thread is very useful, don't want it to die!

Thanks guys!

 

[Gulistan]

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://www.vigortronix.com/subcategory.aspx?catid=124
specs are very close to OEP A262Axx serie
but what about the sound ?

 

[creal]

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

 

[CJ]

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

 

[bancho]

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?

 

[emrr]

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. 

 

[Quayhog]

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?

 

[emrr]

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. 

 

[Quayhog]

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.

 

[emrr]

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). 

 

[Quayhog]

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.

 

[emrr]

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. 

 

[Murdock]

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...

 

[CJ]

you have a 217?!!!

 

[Murdock]

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?

 

[kambo]

Pultec: (Gyraf)

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 ?

 

[Murdock]

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?