New API 525 build thread.

[jplebre]

PETER!!! welcome back!

 

[peter purpose]

Grassy arse.

 

[jplebre]

I was hoping it would mean a new product
Or, that you still had some stock you may want to get rid off

 

[peter purpose]

Stock I have.... new goodies- nada.

 

[agentile1990]

I think I'm interested in going down the rabbit hole with this one. I've built 2 units from assembly manuals(Thanks ClassicApi/Sound Skulptor) as well as wrestled one of those JLM powerstations into a custom power supply. This would be the first build (at least as far as I know) that is on my own.

Are all the parts still available for this build and does anybody have an idea of what they cost per channel?

 

[jplebre]

was quite significant. The hardware+PCB kits are not really cheap (not because they are overpriced, just because there's a lot to it) but the expensive bits go on the 2 transformers per channel and the grayhill doubledeck switch.

£135 for the kit, $25 ish per transformer, £25 per switch (on RS), I went for the CAPI switches which amount to about $50 with the colour inserts (for 2), $18 for the log pots which are hard to find (again, Jeff @CAPI).
I can't say about the BOM cause I always order x3 or x4 the quantity I need. I have an invoice of £200 but it had parts for other builds in there so don't rely on this.

The thing you really need to worry is the VCR2N. Frank at electrochronic had a stash of them but not many

 

[jplebre]

Quick one - anyone experiencing flickering LED's with the unit on bypass (bar mode)?
I had this all along but I thought it was my previous supply which was struggling to keep up the power for all the modules.

I've just built a super duper power supply and the problem is still there. I'd say the meters go off 1 LED at a time at about 2min interval and then stabilise with 4 LEd's off, the last one flickering.

I'm thinking cap, but might be wrong? bad chip?

 

[Scrappersa]

I have a revision of this that looks a bit different on the switch and meter board. There aren't any pads for resistors. I may have missed the information in this thread, but am I missing a board or is this correct?

 

[jplebre]

hi mate
there's another thread for that revision. Api 525 build thread.
this is for the new one only

 

[whomper]

Hi,

Built two units, working great.
One small issue that I can not resolve; consider a task to compress a BD, four on the floor. First BD hit does not get compressed, the rest do. Strange...

This can happen when there is sufficient pause between two sounds going into the unit. Its like the unit needs to wake up via the first signal only to do its work on consecutive signals.

Any ideas?

Thanks,
Whomper

 

[jplebre]

I've seen it happen the other way around on other compressors, due to problems on the release/time constant circuitry.
the compression would change dramatically after the first hit.

That way around, the only thing I can think of is that you have intermittent issues (eg. cold joints, bad wiring, socket issues) or a wrong sized cap.
You say the problem does also occur if there's a pause long enough, so...

sorry not much more info to think about anything more specific.

Have you done the suggested shunt on the attack?

 

[whomper]

That way around, the only thing I can think of is that you have intermittent issues (eg. cold joints, bad wiring, socket issues) or a wrong sized cap.
You say the problem does also occur if there's a pause long enough, so...

sorry not much more info to think about anything more specific.

Have you done the suggested shunt on the attack?

I have do the attack mod. Might it assist? The fact that it is always happening upon first attack and after some pause in signal, it does seem to be related to the attack function, not triggering the comes simon circuit.
I usually use the two units on drums and percussion, so I dial in the attack three quarters to get a somewhat longer attack and leave it there.

Another idea that comes to mind is the VCR2N as I have sourced it off eBay. Might that be a defective one causing this issue?

 

[whomper]

Quick one - anyone experiencing flickering LED's with the unit on bypass (bar mode)?
I had this all along but I thought it was my previous supply which was struggling to keep up the power for all the modules.

I've just built a super duper power supply and the problem is still there. I'd say the meters go off 1 LED at a time at about 2min interval and then stabilise with 4 LEd's off, the last one flickering.

I'm thinking cap, but might be wrong? bad chip?

Just saw this note while going back to this thread. The two units I have exhibit thee same behavior as per the above.

 

[901]

Maybe you could measure the voltage at the gate of the FET to better understand what is happening. I don't believe it's a bad or out of spec component if it happens on Two devices in the same way.

 

[Rob Flinn]

What values are people using for RM1 & RM2 ?    I only seem to be able to light 1 led in comp mode but all of them in bypass, I'm thinking the issue may be these resistor values.

 

[901]

I picked 4k7 for RM1 and 1k for RM2. Works fine.

 

[qmp audio]

What values are people using for RM1 & RM2 ?    I only seem to be able to light 1 led in comp mode but all of them in bypass, I'm thinking the issue may be these resistor values.

See the datasheet for your meter driver.
This is the one I used [LM3916],  has the R values in the datasheet: http://www.mouser.com/ds/2/282/snvs762a-74208.pdf

r1 1.2k
r2 7.6k

 

[qmp audio]

What values are people using for RM1 & RM2 ?    I only seem to be able to light 1 led in comp mode but all of them in bypass, I'm thinking the issue may be these resistor values.

In addition to my above post... my meter does behave a little strange.  When my attack pot is CCW, I get about 1 LED responding.  When attack pot is full CW,  i get full meter range.  Not sure exactly what is going on.  I can hear that the amount of compression correct,  just the meter is responding different based on attack.

 

[Rob Flinn]

Thanks for that info.  That is what I used.  I didn't include the attack pot because of what you guys were saying & shorted the 3 attack pot pads together.  The problem is that I can only get 1 led to light on full compression.  Other than that the module seems to work fine. 

I have a mk1 version of this compressor which only has an RM1 resistor & has no issues with the meter.    I think the meter circuit may be different on the first version & seems to work properly.  Trouble is I don't have a circuit diagram for the meter which makes it difficult to work out the difference.

I suspect it may be more like this circuit since RM1 is a 1k on the rev1
http://www.next.gr/light-laser-led/led-circuits/10-LED-VU-meter-LM3915-l7590.html

 

[Rob Flinn]

Gunpoint, initially I was using the same values for RM1 & RM2 as yourself.  I just tried the values 901 suggested & the meter works properly with them.  I suggest you give them a try.

901, could I ask you how you arrived at those values ?  I was looking at the data sheet but was finding it rather confusing.