JustinS

API 525 compressor
« Reply #20 on: March 17, 2005, 06:57:40 PM »
I know those 2 compressors... Mr Tim Whitten's, he also has a lovely pair of brown ones.  Now if I can only convince him to give them to me!!

Justin


CJ

API 525 compressor
« Reply #21 on: March 17, 2005, 08:22:01 PM »
ytrehalf, i would love to check out that iron.

cj
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

Bauman

API 525 compressor
« Reply #22 on: March 17, 2005, 08:54:23 PM »
Quote
The Quad8 AM2B are great and one of the simplest comps around. They have the original VC2 opto's in metal cans which can still be bought in the modern plastic vactrol package. The one thing to note with these compressors when trying to link them for stereo is that there is no negative feedback in the side chain and to get them to track well you need to match the gain of each transistor. Q1 left = Q1 right etc


Great to know Joe, do you have the schemo???  :green:

 :guinness:
Fabio
cheers!
Fabio
_____________________
www.thediypill.com/store

soundguy

API 525 compressor
« Reply #23 on: March 17, 2005, 10:24:30 PM »
I have full docs for these which Im gonna put up on my site as soon as I get them back which should be pretty soon.

I have a pair that are black which came out of that big oral roberts console.

dave

chips are good with dip...

smilinfu

API 525 compressor
« Reply #24 on: March 18, 2005, 09:42:05 AM »
Thanks for the information! :thumb:

gang of elk

API 525 compressor
« Reply #25 on: March 18, 2005, 11:39:57 AM »
Quote from: "soundguy"
I have full docs for these which Im gonna put up on my site as soon as I get them back which should be pretty soon.



sweet!!  :thumb:


 :guinness:

Bauman

API 525 compressor
« Reply #26 on: April 01, 2005, 12:37:28 PM »
docs bump!  :green:
cheers!
Fabio
_____________________
www.thediypill.com/store

Bauman

API 525 compressor
« Reply #27 on: April 01, 2005, 01:51:03 PM »
was also wondering if anyone got comments about the 225L model. Looks like it can be easier to DIY , any schemo or docs around???

What the old/new switch in the actual 225L A.P.I sells do?

cheers!
Fabio
cheers!
Fabio
_____________________
www.thediypill.com/store

soundguy

API 525 compressor
« Reply #28 on: April 01, 2005, 02:05:17 PM »
old=feedback new=feed forward.  I think the 225L uses that VCAs.

dave

chips are good with dip...

kvintus

API 525 compressor
« Reply #29 on: April 19, 2005, 05:44:47 PM »
Quote from: "soundguy"
I have full docs for these which Im gonna put up on my site as soon as I get them back which should be pretty soon.

dave


bump

/Anders
...not perfect, but close enough for rock 'n' roll...


soundguy

API 525 compressor
« Reply #30 on: April 19, 2005, 05:56:10 PM »
new website:months away...

dave

chips are good with dip...

chrissugar

API 525 compressor
« Reply #31 on: July 12, 2005, 06:52:24 AM »
Hey Dave,

Any news about the Quad Eight AM2B schematic?

chrissugar
Christian Mike Sugar
        CMS-LAB

Sammas

API 525 compressor
« Reply #32 on: July 12, 2005, 09:20:26 AM »
Can anyone shed some light onto how the stereo link works on the 525? I've looked at the schem, but i don't contain the knowledge to even begin to figure it out. How do two 525's work in stereo? I noticed that the newer comp's use pin 6 for stereo link.  Is this just a sidechain input for the second unit? so each compressors controls are still independent from each other and have to be set identically?


or am i way off the mark?

API 525 compressor
« Reply #33 on: July 12, 2005, 10:10:28 AM »
more info on the stereo link from a rec.audio.pro post

Hey... what about a pair of API 525 compressors, linked?  I never actually
heard these.  I wonder how you link them?  wg


connect pin 7 of one 525 to pin 7 of the other 525 through a resistor ( can't  remember the value). I got the info from API a few years ago.
 

wilcofan

API 525 compressor
« Reply #34 on: August 16, 2005, 01:59:48 AM »
I'm trying to figure out the stereo link and I'm not having much luck.  I have a PDF which came from API, handed down from fellow users.  It has the same schematic section as earlier in this thread but with 4 more pages and stereo instructions.  Here's the 525-C for reference:

http://www.bobbymcalister.com/DIY%20Photos/525/525Cschem.jpg

Here's some more of the pdf:



It suggests a switch between pin 7's too but I've tried that (with an 120 ohm resistor) and I cannot get them to respond to each other's input at all.

What worries me is the instructions seem to want to break the connection between 7 and 8 when in stereo (but not quad, just to clarify).  This seems to be reinforced on the schematic here:



Two problems.  First, the pin layout is partly the same and partly different here.  Mine inputs are not set as 5 and 6 like this schematic but rather pins 8 and 10.  My 525's are also labelled 525 B on the PCB and are from 1998.  It would seem this is not the schematic of mine or the current reissue compressor.

Second, there is a physical strap on my pin 7 and 8 which is confusing me more.  I don't know enough about electronics to see the role in the pin 8 on my actual 525.  If it's the same then, if I'm reading this right, it is supposed to be strapped only in MONO!

Can anybody help me here?  I think I'm going to post photos of my 525 tomorrow to help.  Don't have a camera right now.

Thanks,
Bobby

therecordingart

API 525 compressor
« Reply #35 on: November 03, 2005, 12:03:07 AM »
Any news on an A*P*I* compressor for DIY?  Anyone have pdf files of a board layout?

API 525 compressor
« Reply #36 on: November 18, 2005, 09:18:58 PM »
Hi all,

Can anyone tell me if the Forssell 992 op amps would be happy in the 525C circuit that's linked above?

Thanks,
Seth

The definition of insanity: "Hey, this thing could be really cool - if I had the money to fix it up, which I don't, but if I did it could be really cool - if I had the time, which I don't, but

therecordingart

API 525 compressor
« Reply #37 on: November 18, 2005, 11:16:59 PM »
Does anyone have a Gerber or PDF of the board layout??

soundguy

API 525 compressor
« Reply #38 on: November 18, 2005, 11:39:28 PM »
seth-

fred would obviously know best but from what Ive been able to gather about his amps, they'll only drive a 1:1 so that would rule out using a 992 in the A2 output driver position.  Input should work ok.  The new 525's dont have that transformer in the sidechain, its replaced with a chip so you could probably get away with it there as well depending upon which vintage you have.

dave

chips are good with dip...

API 525 compressor
« Reply #39 on: November 19, 2005, 09:25:35 AM »
Thanks Dave,

I was curious because the transformers are not 2503s, they are smaller and according to ytrhalf earlier in this thread they are 2157s though they are unmarked. Interestingly, this 525 that I have does have a transformer in the sidechain, but it's all surface mount components that I can barely see, let alone work on.

Anybody know anything about the 2157 transformer? Primary impedance etc...
Seth

The definition of insanity: "Hey, this thing could be really cool - if I had the money to fix it up, which I don't, but if I did it could be really cool - if I had the time, which I don't, but


 

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