New API 525 build thread.

[901]

I'm glad that you got it to work!

I remember I tinkered around with the formula in the datasheet. 1k and 4k7 where resistors that I head lying around and roughly matched my results.

I also paid some attention to adjust R55 so that all LEDs are lit at the point of most compression. I built two devices and matched both to run as equal as possible. But this was purely experimental.

I wouldn't count on the meters to really show some precise dB values. I guess Peter just exchanged the meter from the schematic (which is an analog moving coil device) with the LM391x with the standard application schematic from the data sheet.

 

[jplebre]

Will give this a go soon too. I need to change the pots law as the current ones are IMPOSSIBLE to do with and will take the opportunity I have them put apart and replace them then.
I'll report back too!

 

[Eliani]

I've just started this build for two units of my own, as promised to Peter I would write down a nice build report, and that started with sourcing the parts. I wanted to make this a little bit easier on everybody, without losing the DIY in the project.

I've ordered all the parts myself, and sure I'll encounter some difficulties...
Maybe some of you need some help sourcing parts, might find it over at:

THE FACTS

While awaiting an order from Jeff at ClassicAPI, more stuff from mouser, Grayhills from Digikey and VCR2N's from the Electro Chronic Parts store, I started building the API 252 compressor. I want to do this step by step, and take note of everything I do, why I do it that way, and why I should do it different next time! It would be nice If you guys would follow my progress, correct my mistakes, and together we could put together a very thorough build guide for Peters 525...

THE BUILD

 

[mica]

Looks like one of my REL pushbuttons died on my 525. It jumps right out on every push and basicly wont stay in. Anyone have a link to where i can get a replacement one?

/M

 

[haima]

I'm not sure of the part number, but someone will have it...

you could always glue the button on the switch with a little dab of epoxy?

 

[mica]

Thanks, but im really looking for a replacement, so if anynone knows where to get them please let me know..

Thx

/M

 

[jplebre]

Hi guys!

Just to say that I installed RM1 and RM2 as proposed by 901.
The unit works perfectly now! Meter tracks well at any speed, and the mod I suggested seems to make the unit work as I would expect it.

Very happy camper right now!

 

[noisywill]

Folks,

Struggling to work out where the pin(s) should go in the Grayhill.  Anybody got any pointers?

Ta,

Will

 

[jplebre]

I used this as a reference. Let us know if it helps:

 

[peter purpose]

I've got a few 525 kits left. Pcbs (including 2520s) and 500 series metalwork only. £80 a pop.

 

[taliska]

Hello,

I'm putting together a mouser cart for a pair of 525s and have some questions regarding the electrolytics caps...

They are: (ordered by value)

C5` 5UF/25V (10UF/25V)
C12 5UF/25V (10UF/25V)
C15 10UF/25V (1000UF/25V)
C16 10UF/25V (1000UF/25V)
C19 10UF/25V
C7 33UF/16V (470UF/16V)
C17 33UF/16V
C18 33UF/16V
C1 250UF/6V (470UF/16V)
C9 320UF/2.5V (470UF/16V)

I understand what they represent, original vs (what peter used), but which ones are people using? I've tended to go with the original unless the original is hard to find, but the C15 & 16 values seem way out...10uF vs 1000uF, and the spacing on the board makes me think that I should go with peter's choice on these caps...any thoughts?

<edit>
To answer my own question a little bit. I'm going with 1000uF, because a quick look at the pcb shows that they're in the power path. So larger capacity should be better than smaller right?
</edit>

Oh, and C7 too...33uF vs 470uF...

Cheers,

Kaz

 

[taliska]

As it's not always easy to find electrolytic capacitors with the right combination of values/lead spacing/diameter/rating etc, I've had to be a little bit approximate with some of my selections. I've used the original values as the target values and where I've had trouble finding exact matches, I've gone for the next largest matching value that is still less than peter's values...someone shout at me if this is a bad idea...anyway, I've gone with the following:

Name        Original        Peter's          Mine              Mouser Type

C5`        5UF/25V      (10UF/25V)      6.8uF/100v    Low Impedance.
C12        5UF/25V      (10UF/25V)      6.8uF/100v    Low Impedance.
C15        10UF/25V    (1000UF/25V)  1000uF/25v    Low Impedance.
C16        10UF/25V    (1000UF/25V)  1000uF/25v    Low Impedance.
C19        10UF/25V                          10uF/100v      Audio Grade.
C7          33UF/16V    (470UF/16V)    33uF/100v      Low ESR.
C17        33UF/16V                            33uF/100v      Audio Grade.
C18        33UF/16V                            33uF/100v      Audio Grade.
C1          250UF/6V    (470UF/16V)    270uF/25v      Low ESR.
C9          320UF/2.5V (470UF/16V)    330uF/25v      General Purpose.

I'm going to order later in the week, so...

BTW, when I was choosing film caps, a few of the WIMAs came up as RF/microwave ones...I they ok for audio use? I assumed they'd just be over spec'd but wouldn't do anything bad or unwanted...correct or not?

Cheers,

Kaz

P.S. The high voltage ratings were mainly by chance / chosen if they were effectively "free" (same price as a lower rated one). I tend to go with higher load life caps if I can as I don't want to spend my days recapping. I've tried to use audio grade caps in the audio path, but that was just me looking at the pcb and following the traces to guess...not very scientific I know, but the labels make it fairly easy to do at least.

P.P.S. Also meant to mention that if people are having trouble sourcing for 1M pots & grayhills, they're both available at Allied Electronics. Specifically, there's a Honeywell 1M pot that is VERY similar to the vishay PRV6s. In fact, I suspect that's some sort of standard military spec code, as the honeywell pots have a similar code too...RV6NAYSD105A and are almost exactly the same size.

 

[taliska]

Looks like I'm pretty much talking to myself at this point, but FWIW, if anyone out there needs the RV6 style 1K log pots and is going to need a lot of them, then the following ebay link might be worth your time (especially if you're US based):

(it's a link to a lot of 25 pieces military surplus for (a buy it now price of) 85USD...obviously don't click it if you're not in the market for 25 pieces yourself, as the extra traffic to the page will only serve to increase the price...)

http://www.ebay.co.uk/itm/PEC-RV6NAYSA102C-1K-Potentiometers-Militery-Grade-Lot-of-25-New-/141370279309?pt=LH_DefaultDomain_0&hash=item20ea53458d#shpCntId

They're apparently these: http://www.precisionelectronics.com/0-40a-060a.html, but it seems to me that that company must have had a name change, because they look a lot more like these: http://www.etisystems.com/RV6.asp (notice the spec and site similarities...)

Anyway, I'm not the one selling them, just an observer, but figured someone else or peter might be interested...especially if another run of 525s ever happens. I didn't buy them myself, because even though RS screwed up my order meaning having to wait until october for the back order to come in, I managed to source some prv6s locally by going with different packaging options. The funny thing is that even with import taxes and expensive shipping, that lot of 25 would have made financial sense if only I was building four 525s instead of two, so there's definitely a bargain to be had there for someone...

Obviously can't comment on their condition, so exercise caution...

Cheers,

Kaz

 

[jplebre]

Taliska for the 1k pots I got them from Jeff steiger at classic api. they were cheaper than the PRV6 and I needed the API style aluminum knobs anyway

 

[taliska]

Taliska for the 1k pots I got them from Jeff steiger at classic api. they were cheaper than the PRV6 and I needed the API style aluminum knobs anyway

Yeah, I probably would have done that had I engaged my brain before ordering my stuff! (after all, I got the xformers from Jeff).

While I've got you here...how are your 525s working out? I've read about the differing wiring for the attack pot and the resistor selection for the meter...was everything else straight forward?

Cheers,

Kaz

 

[jplebre]

working out fine! I had to do the mod I suggested on the attack a few pages back or it wouldn't work as intended.
Wiring the attack like that not only fixed the attack pot sweep, the weird release that happened at some attack speeds and the meter (would stop working at faster speeds).

I know some people did the same mod and agreed on all of the above.

I'm almost sure I went with 1.8k and 7.5k for the meter bridge LED's

its an amazing comp. using it on every project on a bunch of sources

 

[taliska]

its an amazing comp. using it on every project on a bunch of sources

That's good to hear! In that case, I'd better hurry up and get these things built so that I can enjoy the goodness too... 

 

[jplebre]

It's definetly not a clean comp. Lots of colour so it fits some genres/sounds.
Did an hard-rock EP not too long ago where the toms had this goodness all over them. Did a soft jazz/fusion thingy where they staid on the overheads. They are also great on acoustic guitars if you want the colour on them. I need to hurry up and get these 2 going (so I have 4ch)

 

[dmp]

I just read through this thread - I built up the first rev of these.
We've been trying these a lot lately. At first found them a little hard to use because I was trying to use them with a light touch, but lately been slamming them with parallel compression using a SnB. A good friend of mine commented that the added attack knob makes them much more usable and is a big improvement on the originals.

 

[taliska]

I just read through this thread - I built up the first rev of these.
We've been trying these a lot lately. At first found them a little hard to use because I was trying to use them with a light touch, but lately been slamming them with parallel compression using a SnB. A good friend of mine commented that the added attack knob makes them much more usable and is a big improvement on the originals.

That's interesting to hear! I've got two SnB pcbs on their way to me at this very moment for just that purpose. I plan on combining those pcbs with some ruffrecord's db25 pcbs to create a 2U box with 8 channels of blending for parallel compression for these and some other comps I haven't finished yet. Should end up with parallel comp on 2 x 525, 2 x F76, 2 x 176, 2 x pye.

Of course, I'd be much closer to finishing these if I hadn't accidentally got 1/8 watt 3k9 resistors instead of 1/4 watt ones for the mainboard...(I had a temporary moment of extreme denseness when putting my mouser cart together...)

Kaz