Discrete That 1510

So, i am into pimping a audio interface that uses 1510 as mic pres. I am experimenting with different stuff. It's Profire 2626. Got it for peanuts.

I saw JW made discrete 1510 version with superior specs, but i think it would be kind of overkill to invest 8x50$ for a firewire interface i just fool around with.

Does anyone have an idea about something DIY friendly similar to JW's solution?

kingkorg said:

I saw JW made discrete 1510 version with superior specs,...

Click to expand...

The specs of distortion and noise and response and such things for the THAT 1510 are already pretty much near the limit of what can be measured. So I have to doubt the "superior specs" (got link?) and wonder what the point would be.

Here's the link.

http://audioupgrades.com/products/products_pip.htm

ah the pip. It's not 100% discrete. There is a big ol opamp at the center of it.  he likes those video IC's I forget why.

As I have put in and removed a few pip's I can tell you YMMV.

That's just two transistors in front of an op amp. It's not CFIA like the THAT, SSM and INA chips. It's not even CFP near as I can tell.

squarewave said:

That's just two transistors in front of an op amp. It's not CFIA like the THAT, SSM and INA chips. It's not even CFP near as I can tell.

Click to expand...

In front or after to drive some current?

Ok, giving up on those. Thanks for feedback!

pucho812 said:

ah the pip. It's not 100% discrete. There is a big ol opamp at the center of it.  he likes those video IC's I forget why.

As I have put in and removed a few pip's I can tell you YMMV.

Click to expand...

IIRC it's all about the slew rate with JW and the 'video' type ics.
Many would say it's not applicable for audio applications ...Discuss. Or not

pucho812 said:

As I have put in and removed a few pip's I can tell you YMMV.

Click to expand...

I think most techs have un-modded some JW gear during their careers.  :

Was there an issue with the JW opamps, or was it the sound?

I managed to find some comparisons of consoles with his modded and stock channels. Noise levels were exactly the same. I guess even if the opamps were so quiet, everything that surrounds them will be noisier, so...

I'm trying to do something to the unit, just for fun. Some chips with digital gain controll RME, and few others use have such crazy low THD and noise specs, so i was wondering if i could somehow get there.

Maybe zvukofor's  blog gives you some inspiration?
http://zvukofor.blogspot.com/2013/07/profire-2626-modding.html

Newmarket said:

IIRC it's all about the slew rate with JW and the 'video' type ics.
Many would say it's not applicable for audio applications ...Discuss. Or not

Click to expand...

When you reach a certain level of performance, the surroundings become more and more dominant. The benefits of a super-duper circuit, that can probably be measured on teh bench, may become elusive one put into a circuit that has not been designed for it.

abbey road d enfer said:

When you reach a certain level of performance, the surroundings become more and more dominant. The benefits of a super-duper circuit, that can probably be measured on teh bench, may become elusive one put into a circuit that has not been designed for it.

Click to expand...

reminds me of a saying

If it measures correctly but sounds like shit, you have measured the wrong thing.

Click to expand...

mjrippe said:

I think most techs have un-modded some JW gear during their careers.  :

Click to expand...

He's a big fan of specs. Pedestrian concerns like reliability isn't something he is concerned with.

Gerald Jansen said:

Maybe zvukofor's  blog gives you some inspiration?
http://zvukofor.blogspot.com/2013/07/profire-2626-modding.html

Click to expand...

Thanks. Did the over the top cap value/type thing around two channels, and one AD DA chip, and it did exactly nothing, as far as i could measure, and do null test.

Linear PSU is hard core overkill. Even Zvukofor admits that in one post. No ripple i could measure anywhere, and the thing's audio is linear, and clean up to 90khz at 192 sampling rate.

One thing i did, which hardly does anything good for THD, but does affect the sound, is install two 200:200 Paso(italian) transformers instead of phantom blocking electrolytics. I got different 2nd and 3rd harmonic content, and off course higher THD. So i guess i have two vintage channels now. LoL!

There is a claim by BLA that if current limiting circuit is removet from the outputs, the sound opens up significantly. Which ii did remove, and that did exactly nothing!

Here's the pic of output limiting section.

Leave the THAT1510 in place, it is not a bad chip and you will find them in much more expensive gear than the Profire. You could swap for the SSM2019 too, but it would be more like a side-step than any real upgrade. I have just rebuilt an old Rane DMS22 with That 1510's and I can say the best thing you can do to these preamp topologies is to upgrade the output opamps and coupling caps. I used AD845 with good results. The AD845 will draw pretty high current, but will most likely operate in class A.

Leave out any unnecessary componentry, and run the THA T1510 direct coupled into your output opamp of choice.

If you want colour a 1:2  input transformer might be a good idea.

Cool, thanks!

mjrippe said:

I think most techs have un-modded some JW gear during their careers.  :

Click to expand...

well as my buddy says 

he started doing guitar amps and he did the best thing for them, he moved onto something else.  Unfortunately, that something else was pro audio.

Click to expand...

That one was good

So does anyone here have opinion about removing output mute transistors, and their effect on sound? I guess it's the same circuit BLA calls current limiting circuit. Not sure if it's the same thing though.

pucho812 said:

well as my buddy says

"He started doing guitar amps and he did the best thing for them, he moved onto something else.  Unfortunately, that something else was pro audio."

Click to expand...

Hmmm, the rumor I heard was that he started with Linn Drum machines, but it really doesn't matter.  His philosophies do not translate to real world experiences.  But that is for a Brewery topic perhaps...