gar2520 build thread

fragletrollet...

Very Nice CLEAN Job!!

Congrats

GARY

Thank you Gary, considering I`m just starting I feel a little proud 

I was most concerned about shorting the pads closest to the millmax pins to the millmax sockets. In retrospect, after looking more at the photos, it looks like it wouldn`t have mattered anyways, as they are traced anywways?

So I recently built 6 gar2520's for a pair of fc526's, and 5 worked out great. After realizing I'd put the BD transistors in the wrong spots, I decided to replace all the caps/ transistors/diodes to be safe. I didnt replace the resistors as they all tested fine.
After A/Bing the new op amp to the others I've noticed the rebuilt op amp sounds like it has a HPF.
The compressors definitely aren't an issue as they work great with good opamps.
Any Ideas on what could be causing this?

Dear people,
I've built around 12 x 2520 and 6 x1731. They all work, verified in VP25,VP26,AnalogAllstars,and TB550a projects.

I also happen to have an Api2500 stereo compressor that lost one 2520 opamp. Well,you know..
I made sure I could fit the "short legged"  gar2520 in (bij moving/resoldering a cap that is in the way,under the opamp) So far so good,verified with the one still working APi2520 opamp.

I inserted a Gar2520,switched on and was greeted by massive noise. Not good.  Tried another one,same result. Tried a third,same noise. Note that all these opamps were tested,and working. Trying them in a vp25 again, which verified that they still  work properly.

I then put in a Gar2520 whilst the machine was on.Yes I should'nt have done that.. But it worked,and sounded fine. Weird..? I then switched off the compressor, switched it on again,and again the loud noise was there. It was even audible when I switched to bypass (2500 uses relais for that),so it must be quite spikey... Trying that opamp in a vp25 again verified that it is still in a good shape.

Has anyone encountered such a problem in the 2500 compressor? Is there a solution?

Thank you,
Pieter

Can anyone (Gary/Gar381) tell me what surface finish is used for the two DOA PCBs available from Jeff @ ClassicAPI, please?

As they're not gold plated, it is unclear whether they'll be leaded or lead-free HASL (or something else?).

Thanks!
Tom

Tom..

HASL -Hot Air Solder Leveling

GARY

OK - cheers - leaded solder it is then...
(slight sigh..)

[these days, it is as cheap to get RoHS boards as non-RoHS. Lead-free boards can be used fine with leaded solder, but not vice-versa, so I would suggest producers moving to RoHS - would not in anyway stop builders who like the lead still sticking with their old ways]

Kester 44      63/37 recommended. 

GARY

Hello everyone!

Is there a way to test 2520's & 1731's without pluging them in a module? With a DMM for exemple?

Thank you,
G

Golgoth said:

Hello everyone!

Is there a way to test 2520's & 1731's without pluging them in a module? With a DMM for exemple?

Thank you,
G

Click to expand...

Without some sort of test jig,  plugging them into a working module is the best way.

GARY

Hi, noob on building DOAs - have built a number of SCA pres, guitar amps, etc., and decided to try the gar2520.  When I power up, Q8 gets very hot quickly.  I've checked that Q7 and Q8 are in the proper locations and correctly positioned, and have been through looking for solder bridges / shorts between leads.  I know I did something wrong, would appreciate any advice on where to look.  thanks much!

BTW, have tried at +/- 16 and 15 volts, no higher.

Hey guys!

I'm working on some gar2520s and I ordered quite a few BD139-6 instead of BD139-16 by mistake - too much work right now. Do you guys think using 139-6s is negligible in this circuit?

Thanks in advance and best regards,
Mathias

Hi Mathias

The only difference is hFE.  I have used BD139-10 in the early days
of this DOA and could not hear any difference.  hFE on these outputs
is not that critical.  I never tried the -6 version.  I would use -16 guys
if you can get them but try the -6 in one and See what it sounds like.
You might be OK.

Best

GARY

Hi Gary!

Thanks for your help!

I tried one with a -6 version and this one seems to distort a little bit earlier when pushed harder than the ones with the -16s (tested in VP26s). I guess the question should have been more like "is it ok to mix BD140-16 with BD139-6, or will I face serious problems with asymmetry in the output stage?"

Best regards,
Mathias

Hi Mathias

Sounds like you might be happier  using the -16 guys.

Best

GARY

Hi Gary!

Alright, I'll get some -16. Thanks for the quick help!

Best regards,
Mathias

Does anyone know if you can use 1n4149's in this instead of 4148's.

I've built 28 for a mixer and I soldered in the wrong ones already. Spec sheets seem to look more or less the same.

Cheers

Hi Jess

Never tried the 1n4149 but it looks like it should work.  Fire one up
and see how it sounds.

GARY

gar381 said:

Hi Jess

Never tried the 1n4149 but it looks like it should work.  Fire one up
and see how it sounds.

GARY

Click to expand...

ok cheers gary, its a while before the mixer is complete though.

i read on another forum that 1n4148 is 20pf and 1n4149 is 10pf if that sheds more light?

I built my first gar2520 and it did not work. So I built 2 more and these are not working either. I dont even know where to begin to try and trouble shoot . I have a magnifing Lamp and can see pretty well that there are no shorts/Bridges. all that I can think of is maybe I got a component to hot ? I have been soldering for years, not on things quite so small but it didn't seem like I got anything to hot. Anyway any suggestions on where to begin on trouble shooting would be helpful.

Thanks much,
Thomas Thew