MS, Pultec, 1/2-BA283 boards support thread!

[ilfungo]

Sorry for delay....
I do not know if I was lucky, but I was not careful for orientation ....
No R1

 

[DAN_000]

Ciao Dan
Igor says me:

"for 31267 or Carnhill substitute, see bom"
I think that  in Bom's values are correct...
how do you modify the gain switch from 2db to 1 db?
Thanks!!!

What bom ? I cant find it

Thanks

 

[ilfungo]

This

 

[ilfungo]

This is all that I found on stepped Pultec
I hope he can help

http://www.megaupload.com/?d=1C137T1C

 

[zayance]

yeah there is a mistake here with this design.

A confused legend.

Which values should I trust.

The 'cut and paste' pultec values that are on the schematic, or the values of a carnhill 9054.

If i install the carnhill, Colin at AM won't refund me.

I really just need one simple answer at this stage.

I kinda wish Igor would indulge us ( as other designers do, EZ1290/Ad760 etc etc ) and post a build guide.
:'(

Hi sorry for jumping in, i actually don't build this one, but just want to help if what i'll tell will  .

So if i understand clearly, problem is the inductor from Carnhil physically and specifically doesn't match at all PCB and Schematic Accordingly.
IIRC Igor said when doing this project that he would have some local supplier, supply him with those inductors, so i guess that's what he did, and that's where you are, and the Carnhill doesn't fit PCB (that kind of mistakes happens even to the best of us, even if i don't think there is any mistake, beside saying the Carnhill works there, as it seem not from the inductances, but all would work in a way.)


Now 3 solutions, i'm not a DIY and Electronic Pro, so if i'm saying stupid things please let me know Guys, it will help me out as well  ;D.

First solution:
Using something like this called a Nomograph (since it's a passive Eq), i remember radiance sending me one, and it seems i lost it, cool that i found another one anwyay,
so with this you can tweak the frequencys to your needs with this, of course the caps values may be hard to find, or may need to be connected in series/Parralel to give you what you need going with the different inductance the Carnhill or else will give you.
So basically, what you'll need is a veroboard  and hardwire connect from the Vero to Igors PCB, not the illest solution neither, but i guess it would work also, got to be carefull not to mix up the connections tough.
This solution is a little more time consuming than the idea behind buying the PCB and installing and voila, but a solution i guess.
http://www.beis.de/Elektronik/Nomograms/RF-WP/RF-Wallpaper.html

Second solution:
I don't know if you've seen this, but a Forum Member called "Who" sells most of all parts needed for the Pultec Project.
Check this
http://www.don-audio.com/-EQP-1A-inductors-DIY-for-Pultec-EQP-1A-Diy-projects-inductor

As you can see he has those inductors, even in matched pair, (different footprint tough) but with the correct inductance going with the Schemo, and so the original Pultec.
Same here, it would need a veroboard mod.


Third solution
Maybe better adapted afterall
Another forum member makes custom and Pultec inductors, his Forum name is "Chrion" and here is his thread:    go up
http://www.groupdiy.com/index.php?topic=43429.msg559693#msg559693
Chrion's footprint looks better but you should check that with him maybe, i say this taking a quick look at Igor's PCB frist pic on first page, at first i tought 9054 is maybe the wrong one and that's that, footprint was more like a 9048 or something.


Anyway maybe this will help, now the rest of the connections,  but as some others said, looking at the Schemo i'm sure you'll get the point.
Concerning the Zobel i can't help, it all much depends on what tranny you're using, but there are a lot of infos around here and on the web for them, of course you could still open a thread for this question.


Good luck!

 

[muffy1975]

INDUCTOR MADNESS,

the 9054 is the wrong size to be mounted on the PCB. A problem YES, but no big deal.

What is a BIG DEAL are the inductor  values.

Does Igor want us to use the values of the 9054?

Or does Igor want us to use the values common to the Don Audio inductor/Sowter inductor etc? That later are the standard values for these pultec projects.

The 9054 appears to have the wrong values. Does Igor want us to use these values? Which are the correct values?

WHERE IS IGOR???? Why won't he answer this question? It's hardly a scandel, no need to hide etc ;D

I'm beginning to feel like a journalist tryting to get an answer out of a poltician

Anyhoo to the who? ;D

Peace and etc ???

Michael

 

[zayance]

INDUCTOR MADNESS,

the 9054 is the wrong size to be mounted on the PCB. A problem YES, but no big deal.

What is a BIG DEAL are the inductor  values.

Does Igor want us to use the values of the 9054?

Or does Igor want us to use the values common to the Don Audio inductor/Sowter inductor etc? That later are the standard values for these pultec projects.

The 9054 appears to have the wrong values. Does Igor want us to use these values? Which are the correct values?

WHERE IS IGOR???? Why won't he answer this question? It's hardly a scandel, no need to hide etc ;D

I'm beginning to feel like a journalist tryting to get an answer out of a poltician

Anyhoo to the who? ;D

Peace and etc ???

Michael

I'd go with the Schematic Values.
At the end it's a Pultec with more control on the frequencys achieved with stepped lorlin and RC / RLC network, but the same

Just my 0.02cents.


PS: If Igor doesn't show up, i guess it's because he wants you to do some research as well, he helped for years people that bought stuff from him, and maybe he feels overwhelmed with all this, other non Audio projects, Business etc.... Life at the end.

 

[Sylvain D.]

I agree with Zayance.

Igor has given L O T S of info on this forum and he did tell us that he would be "away" for a while because of his new job and travel time etc...  He has given us great projects of a level that I have not seen anywhere else.    Let's cut him some loose.


Syl

 

[Igor]

Hi to all!
I had very busy time for last months, the time for road from Haifa to Tel Aviv
takes about hour and half each side, and freelancer's day at local hi-tech is never limited.
The most time-sucking project is finished, I did some cash for making fun, audio and have some free time.

VERY sorry about leaving support threads abandoned.

Bugagaga, Bender is here again!

Now, let's try to figure out and fix .

Internal wiring and 1/2 - BA283 stuffing... hope, it is clear:
http://ij-audio.com/downloads/pult2010_MS_wiring.pdf

All this IMHO is possible to figure out from schematics.

Please note:
Ed Anderson's EA-10468 transformers, connected backward, are shown at this drawing as input trannies.

For 31267, VTB9046, VTB9071, etc, every needed info is printed right at MS/Bypass PCB, on connectors:

PRI+/-, SEC1+/-, SEC2+/-. The rest: RTFM (transformer's datasheet).
Primary half's are connected in series (one connection at transformer).

Zobel networks were tested with 31267 and EA-10468.
The values shown in BOM are used not to "over-cut" the transformer's transient response.

Of course, other trannies can be used, just keep in mind, they should have symmetric windings for secondary's.

Output transformer's I used are VTB9049 and EA-1166.

Inductors.

I used local supplier for inductors, and added VTB9054 package on PCB which one of guys shared with me.
I never tested the EQ with 9054, as I wrote.

So...here we go.

I will order 30 inductors this week, they will be ready within a 10-15 days; a part of them will go for my use, 
the rest will be offered for low as possible cost at web store, it comes up with all possible worst case conversions about USD35/pair.

The PCB, BTW, shows inductor's values,

And of course, you can use your DIY inductors as well.

Take a core, wire, make 100 turns, measure, calculate Al, here we go...at all, this is DIY.

Please note the dot and right placing, if use my inductors:

Well... I hope, the .pdf file will spot some light on mysterious sorcery; the rest of docs can be found here:

http://ij-audio.com/downloads/

 

[Igor]

Here are some pictures of another assembled unit (I did 5 till this moment).

http://s251.photobucket.com/albums/gg291/diy33609/PULTEC_MS/Pultec_SugarHill/

You can use these photos as "build pictorial".

Mind the power trafo placing, this way, I got best possible S/N.

Here, Ed Anderson's transformers are used, and they sounds awesome. The input is MIC INPUT (EA10468) wired backwards.
It's "secondary" used as primary, holds 20Hz, +18dbm with 0.4% of distortion. Good point to get some nice color from pushed hard unit.
At +4dbm, the low freq. distortion is absolutely negligible.
Both input and output tranny's have perfect windings symmetry, this allows to have
about 75 db L/R separation after LR-MS-> MS/LR processing, which is nice spec for passively MS'ed unit.

The thing I discovered, at least with 2 input transformers:

the datasheet says:
BRN Start, BLK End for primary;
ORG start, VIO end for secondary.

Maybe, I had 2 wrong transformers, BUT I had to reverse ORG and VIO to get right phasing.
I checked with another transformers, the phasing was right without reversing.

Easy way to check the phasing, is refer your scope EXT trigger input to oscillator's out,
connect channel's probe to OSC out, catch the sync, and mind where the sinus starts.
Than, connect the trafo between the osc. out and scope input, polarity: start is + (signal), end is ground,
the sinus at scope's screen should start at same point. If the sinus is reversed, you have reversed trafo polarity.

Well... If somebody have a progress with his unit and/or questions, write!

 

[bastrika]

Hi, i have found some time to finish this project .

Use EA10468 on inputs , and Carnhill on outputs, diy inductors .
Mine EA10468 are phase reversed too , on secondary .
i've not tried this at studio , but i can say the unit is full working  L/R , M/S , filters and make up .
I tell you about the sound next week.
Bigger pics here:
http://twin-x.com/groupdiy/thumbnails.php?album=441
Thanks to Igor.

 

[KasperNyhus]

Hey all you good guys

Im a little bit confused here...

first, the carnhill input tranny is supposed to be wired in backwards also, right? I have used the Rload values from the bom...

second, am I supposed to use 12v relays? From the pictures Igor is using 24v, and that is what I have bought also, but they need to be feeded with more than 24vdc to flip - with 31vdc I think they all switch correct, but Im not sure...

Then I have a significant cut in highs when I send audio through, any idear what that could be? The controls on the front are working or at least the low-mid freq bands...

Thanks,
Kasper Nyhus

 

[bastrika]

I've tried at studio ,and this sounds huge on 2 mixbuss
@Kaspernyhus , relays are 12V, take a look at schematic or pcb and you will see they are in connected in series, so you have to use 24 Vdc on Vrel connector . I think that Igor's contact relays are 24Vdc/1A ,  maybe this leads to confusion

 

[KasperNyhus]

I've tried at studio ,and this sounds huge on 2 mixbuss
@Kaspernyhus , relays are 12V, take a look at schematic or pcb and you will see they are in connected in series, so you have to use 24 Vdc on Vrel connector . I think that Igor's contact relays are 24Vdc/1A ,  maybe this leads to confusion

Thanks bastrika! Ill try to source some new relays...

Can anybody please give me a hint on how to wire the carnhill 9046 input transformers? Now I looked at the right datasheet from audiomaintenance I see that the EA and 9046 are different so maybe they are supposed to be wired in "normal"?

 

[KasperNyhus]

I've tried at studio ,and this sounds huge on 2 mixbuss
@Kaspernyhus , relays are 12V, take a look at schematic or pcb and you will see they are in connected in series, so you have to use 24 Vdc on Vrel connector . I think that Igor's contact relays are 24Vdc/1A ,  maybe this leads to confusion

Thanks bastrika! Ill try to source some new relays...

Can anybody please give me a hint on how to wire the carnhill 9046 input transformers? Now I looked at the right datasheet from audiomaintenance I see that the EA and 9046 are different so maybe they are supposed to be wired in "normal"?

Well, a couple of hours rereading the original schematics and compare them to igor's solved the problems.

With the relays changed the bypass worked. About the high end roll off I found that I had used 220 and 330nF instead of pF! both C2"1 and C5'1...

and finally the carnhill vtb9046 has to be wired in normal to remain unity gain... so that must be all my questions answered...

It sounds great now in LR mode, but Im a little bit confused about the MS. When I listen to a stereo track through headphones it sounds like some sort of phase problem? I mean with MS on but no eq changes it should sound like the original stereo track, right? Apart from the 6db gain loss?

Kasper Nyhus

 

[craigmorris74]

If I'm using a different a different EQ (and input transformer) or a passive summing network with the 1/2 BA283, do I just connect the output of these devices to J13 adn J14?

Thanks,

Craig

 

[KasperNyhus]

When I check the EQ with my scope I get some odd readings.

This is a 1k sine wave put through the unit when bypassed (both left and right)

This is with the EQ in: (there is only a slight boost in gain)
There is no difference between the left/right ch. - the curves line up perfectly...

But now in MS mode:

Now I see why I heard some sort of phase problems...
Can someone explain me whats going on here?

Thanks,

 

[KasperNyhus]

SOLVED: I had flipped the channels going from the MS board to the makeup gain boards.  :

Now it works like a dream, thanks!

 

[izzi]

Hi everyone,
I have this kit and have now constructed it.... However.... This may be quite silly of me but:
1, where do I wire the power switch to?
2, what is the difference between the 'in' and 'eq' on the middle switches?
This kit looks awesome and I must say was by far the most time consuming to construct, and I have already built an La2a and a 1073 pre which turned out better than i could've hoped! Just hope this eq turns out as good as it should!  :-\  ;D

 

[KasperNyhus]

Hi everyone,
I have this kit and have now constructed it.... However.... This may be quite silly of me but:
1, where do I wire the power switch to?
2, what is the difference between the 'in' and 'eq' on the middle switches?
This kit looks awesome and I must say was by far the most time consuming to construct, and I have already built an La2a and a 1073 pre which turned out better than i could've hoped! Just hope this eq turns out as good as it should!  :-\  ;D

1: the transformers primary?
2: the "eq in" is a switch to bypass the filter section of one or both channels, and not as the other (true)bypass switch that bypasses the whole circuit.

/Kasper