Mod a Behringer T1953

[quote author="clintrubber"]FWIW, here's somebody using it as a starting point for 'ribbon-optimized-preamps'...
http://www.proaudioheaven.com/index.cfm?CFID=41284609&CFTOKEN=15476424
No idea if he's just swapping the opamps (for Burr Brown 2134) or does some other tweaks as well.

http://cgi.ebay.com/Upgraded-Behrin...yZ119018QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Steve said most of the sound was the opamps so he put the very best, Burr Browns, in all stages. The gain increased by at least 30% the noise definitely decreased by more than 80%.

Click to expand...

Hard to believe though that the stock unit doesn't reach the front-panel advertized gain - but that were of course the not too scientific words of the happy customer...[/quote]

Unless there are a number of other modifications, I'm inclined to think that the comments are hyperbole. My experience with the OPA2134 is that it is a step up from the TL072/74, but pales in comparison to the AD825, AD8599, and LM4562. It's a little quieter than the old TLO72, with a smoother sound. I found it a bit dark and "phased" in the highs. Even the OPA2132 sounds a bit better than the OPA2134, IMO (a bit more open on top).

FWIW, I'm using the AD8599 and LM4562 in place of the JRC4580s in my Behringer UB1204-PRO. The mixer has a pair of 2SA1084s (which are supposed to be quite good transistors) at the input, followed by the op amp. I've also replaced the coupling capacitors with Panasonic FM series, and bypassed them with poly film caps. I hope to compare the modded UB1204 to some better preamps in the next few days. A friend of mine has an Avalon and a few other nice preamps.

[quote author="12Bass"]Unless there are a number of other modifications, I'm inclined to think that the comments are hyperbole. My experience with the OPA2134 is that it is a step up from the TL072/74, but pales in comparison to the AD825, AD8599, and LM4562. It's a little quieter than the old TLO72, with a smoother sound. I found it a bit dark and "phased" in the highs. Even the OPA2132 sounds a bit better than the OPA2134, IMO (a bit more open on top).[/quote]
Thanks for chiming in.
The Sank-mod mentioned replacing by (8) 2134's,
but that concerns the original 4580's, not 072-sections (8 opamps/side in each signal path, so since these are duals we'd be needing 8 packages).

The 'tube-gimmick' does use TL07X-stuff though: two TL074-sections/side. Don't know what they did with that - probably nothing since we had already reached the quoted eight.

Now I don't know how much the 2134 i.s.o. those 4580's would already brighten the sky.

Regards,

Peter

[quote author="clintrubber"]The Sank-mod mentioned replacing by (8) 2134's,
but that concerns the original 4580's, not 072-sections (8 opamps/side in each signal path, so since these are duals we'd be needing 8 packages).

The 'tube-gimmick' does use TL07X-stuff though: two TL074-sections/side. Don't know what they did with that - probably nothing since we had already reached the quoted eight.

Now I don't know how much the 2134 i.s.o. those 4580's would already brighten the sky.[/quote]

Missed that part....

If replacing the JRC4580, I would suggest the bipolar LM4562 or AD8599 rather than the FET OPA2134. These new low-noise, low-distortion bipolars should make a noticeable improvement (I found the JRC4580 somewhat harsh and murky, with slightly distorted highs). If you are looking for more warmth use the AD8599, or LM4562 for greater transparency.

Thanks for the suggestions for alternatives - and prices are still not through the roof, so taking these along for that rainy day :thumb:

I saw the T1953 runs at +/- 17V, so all these types will fit w.r.t. supply rails.

Regards,

Peter

I am slowwwly working on modding one of these for a friend. i replaced TL074 with TLE2074 and i am going to use 5532 for 4580 on one channel, have not bought chips for the other channel yet, though I am thinking to change my mind from 2134.

I also have Edcor WSM600:600 for the output trafos. I can only imagine that getting original transformers would be nearly impossible without ripping them out of a DI.

i have replaced all the caps in the PS with Panasonic FC series. I need to post pics sometime.

HTH!
Charlie

The signal always goes thru the 12AX7, might want to try different tastes there as well.

I was looking for parts on the web today, $7.00 each for the op-amps and there's eight of them. I'll have to do some more research on that part. I've got the front PCB right here and there's plenty of room, doesn't look like a problem getting to the components. Just the issues of poor layout ( add the 1uF shunt caps), and risk of pad damage(either flood the leads with solder so the chip adheasive melts, or lift each leg and then pop the IC off.

[quote author="walter"]I was looking for parts on the web today, $7.00 each for the op-amps and there's eight of them. I'll have to do some more research on that part.[/quote]
Hmm, that's a bit steep - at least in relation to the original price for the unit itself... or turn it around and thinkabout it in this way: box was cheap, so mod-parts may cost a bit more.
But please let us know when you've found some nice alternatives.

Regards,

Peter

I have a Tube Ultrafex T1954 here collecting dust (it's not connected and not even in the rack anymore) and i'm thinking of modding it as well.
Does anyone have schematics for that machine and know if it's worth a try to mod it with lets' say, better opamps and maybe different tubes?

The seventh post in this thread contains a link to the original T1953 thread. There's some good info there about op-amp swapping and cap upgrades. I have added a high voltage transformer to my T1953 and now the tubes work. The T1954 is not much different with respect to these mods. I'll put (getting that schematic up) on my list. I also have a T1954 that is on the list.

whats the difference in sound with the tubes "working"

i have one of these collecting dust in the storage room of my studio and would like to do something with it. untill i read this i was trying to figure out what to put in its case.

That's a good question. Stock, turning the warmth knob has little or no effect on the sound. With the high voltage, a change is quite apparent. I threw that transformer in and ran a cd through the unit for a minute just to see what would happen. It's been sitting for several months. My plan was to compare a stock unit to this modified unit. I'm just getting around to it. I'll let you know what I find.

that would be great, if you could post a flac or ogg A/B, your praises would be sung of years to come...


...well maybe not, but i would say "thank you"

I just dismanteld my tube ultrafex T1954 (it was collecting dust in the closet for about 2 years) so i thought it was fun to try modding it with better opamps and stuff, if it fails.. to bad, i have a nice case, some meters, knobs and tubes

I do have a question, i see a lot of 4580 7071g opamps and a few 4580 9043g versions, what is the difference as they both start with 4580.
Can i replace those opamps with regular 5532 smd versions one on one or do they have a different pin layout? I have like 20 of 'm here because i ordered wrong 5532's some time ago.

I will make some pics of the boards later on for you board freaks

[quote author="dagoose"]I do have a question, i see a lot of 4580 7071g opamps and a few 4580 9043g versions, what is the difference as they both start with 4580.[/quote]
In general, the 9043 will/can be a date code (43th week of 1990) but if you're sure about the 7071g then it'll be most likely something else, surprisingly so though.

Either case, ignore these figures, it's just about '4580'.

OK, thanks! Thought of that too, the fuinny thing is that the 9043g one's are on one side of the board and the others are used differently.
I also found out that the pinout of the 4580 and 5532 are exactly the same so 'easy' swapping.

Five years later.....Here are the pictures I took five years ago.