PYE Compressor/Limiter Thread *boards shipping* BOM up!

[Biasrocks]

If you have decent skills you should be able to get these up and running.

If you love DIYing then you will continue to refine the tuning of these mainly through time with a scope and meter and a handful of transformers.

I'd prefer to have a base build with a  bom that works, I'm not sure that's currently the case.

After that's accomplished, then certainly there's plenty of room for experimentation and improvement.

That has been the way I've done the majority of my DIY projects for the past number of years, from LA2A's to 33609's.

There are no flaws in the board, but some in the BOM.  YMMV.
Best,
Bruno2000

Perhaps we could compile a list of changes / mods that are required in one place so that they are easily accessible.

I'll start.

TIP :  Make sure that you have the wiper connected on trimmer R44.  Depending on the particular type of trimmer you use it may not be, due to a fault on the pcb layout. You may need to add a bridge between pad & wiper. This has been discussed before.  If you do not have this connection you will get through quite a lot of 1n400x diodes in the psu part of the circuit because they burn up ....

IIRC this is true for ALL of the trimmers except the Voltage adjust.
Best,
Bruno2000

Mark

 

[desol]

If you have decent skills you should be able to get these up and running.

If you love DIYing then you will continue to refine the tuning of these mainly through time with a scope and meter and a handful of transformers.

I'd prefer to have a base build with a  bom that works, I'm not sure that's currently the case.

After that's accomplished, then certainly there's plenty of room for experimentation and improvement.

That has been the way I've done the majority of my DIY projects for the past number of years, from LA2A's to 33609's.

There are no flaws in the board, but some in the BOM.  YMMV.
Best,
Bruno2000

Perhaps we could compile a list of changes / mods that are required in one place so that they are easily accessible.

I'll start.

TIP :  Make sure that you have the wiper connected on trimmer R44.  Depending on the particular type of trimmer you use it may not be, due to a fault on the pcb layout. You may need to add a bridge between pad & wiper. This has been discussed before.  If you do not have this connection you will get through quite a lot of 1n400x diodes in the psu part of the circuit because they burn up ....

IIRC this is true for ALL of the trimmers except the Voltage adjust.
Best,
Bruno2000

Mark

Actually, that's exactly what I'm doing at the moment Mark; re-compiling a new BOM, double checking all parts for lead spacing, values, etc. I learned the hard way not to entirely trust someone else's BOM(I'm sure we all have). No offense to anyone, but I definitely prefer customizing my own parts as per the board and appreciate anything that's been provided thus far.

Trimmers need (i believe) to be installed along the 'base -T' of the footprint that's provided on the board I think, with the leads being 3 inline.  For the transistors, I'm assuming that with the originals, they install as per the footprint on the board and replacements need to be backwards...

For the input transformers, I have two Trident A range line inputs(10k-10k - 1:1) that I'm planning on using for the PYE.
I'm pretty excited about it.  It's been a while, but I'm gonna get on this now.  Be nice to see Abe around these parts again. From what I've heard and seen, it's a nice sounding unit.

 

[desol]

Cheers to mdainsd and others who have contributed information to the thread. You guys are a huge help, after reading through the whole thing. I hope I can get mine up and running as well...  ;D

 

[mdainsd]

You can! Just ask away here if you have questions. I always check this thread to see how others are coming along.

Be sure to find the schematic I posted in this thread, I think its around page 19

These compressors are well worth the effort.

 

[desol]

Quick question Mdainsd.  Where did you source the boards for your relay bypass? It looks like a good idea that I'd like to implement as well.

 

[Quantum J Audio]

Quick question Mdainsd.  Where did you source the boards for your relay bypass? It looks like a good idea that I'd like to implement as well.

Dave, who designs the Don Classic gear kindly drew a relay circuit for me to put on perfboard.  Have uploaded with this post.

I've still being trying to work out what is going on with my meter. 

Is it correct that adjusting R52 (release) should change the meter reading when no signal is present?  adjusting this and the meter trim I can zero the meter.  This also gives me the shortest possible release which I do like the sound of.

Can any one shed any light on what is going within the circuit? 

 

[mdainsd]

Quick question Mdainsd.  Where did you source the boards for your relay bypass? It looks like a good idea that I'd like to implement as well.

ebay. heres one like mine. I think I paid 2.99 each for mine.

http://www.ebay.com/itm/Two-DPDT-Signal-Relay-Module-Board-DC12V-Version-for-PIC-Arduino-8051-AVR-/130690277968?pt=LH_DefaultDomain_0&hash=item1e6dbf6250

 

[mdainsd]

Quick question Mdainsd.  Where did you source the boards for your relay bypass? It looks like a good idea that I'd like to implement as well.

Dave, who designs the Don Classic gear kindly drew a relay circuit for me to put on perfboard.  Have uploaded with this post.

I've still being trying to work out what is going on with my meter. 

Is it correct that adjusting R52 (release) should change the meter reading when no signal is present?  adjusting this and the meter trim I can zero the meter.  This also gives me the shortest possible release which I do like the sound of.

Can any one shed any light on what is going within the circuit?

My relay board is wired differently, but either way will work.

Im at work so Im going by memory...I started by injecting a 1Khz sine wave at -24dB into the input, with the input attenuator  wide open (short circuit position). I had the scope on the end of R50 designated with the square pad. Then watching the steady state DC, I adjusted R52 until that level just barely started to move from the no signal level. If Im recalling correctly, I then increased the input by 20dB and adjust R42 for a meter reading of 20dB gain reduction. As you can see in the picture of mine the meters sit so damned close to zero with no signal, that Im not going to bother messing further with it. And if I did, I would use the mechanical zero on the meters as we are talking less than the width of the zero marker on the meter.

Note: only the -24db input will be in calibration with the front panel markings depending if you used a pot or a switch. To get it to track the front panel markings for threshold you have to build true 40dB stepped attenuators @ 2dB/step. The output control markings are all hosed up so, there is no making it match those markings at least on the case I have.

The hot ticket is to put it back as original with the two stepped attenuators ganged together, with one in reverse of the other. Plug the output hole on the front panel. Or add a make up gain section and put the control for it in there and disregard the markings...

I hope this helps, a little?

 

[desol]

Thanks for the links! 

 

[shot]

Few days ago I've finished stuffing two boards of Pye...

Today I had a little spare time and I was rushing to do the wiring on one of the channels and to power it up.
When I switched it on, I don't know should I be happy or not!

It is passing audio but it's a bit noisy. White-ish noise, no hum or buzz. But a bit too high it seems.

It is working only in limit mode. Limiting is very nice, but with a bit of thump on the attack.

Vu meter seems to work! I was expecting to have meter all over the place without any logical sense to gain reduction, but it sits on a steady position and it is reacting to peaks that it is limiting. I'm using meter from ebay and scale is generic 0-1ma. It is sitting steady on 0.2ma and goes higher when gain reduction is applied. I'll probably do a custom scale for those meters after measuring it's deviations.

I haven't calibrated the chopper yet! Had no time to do it! I had less than half an hour to do the rest of the wiring and turn it on.
And the bad thing is that I have to travel tomorrow and I'll be gone for a week, so my impatience will turn to agony!

My units are built following the SR1200's BOM but with one exception - I've used 1:2 edcors on both interstage and output. That's what I had around!

Now I'm wondering if I wired output transformer wrong way.
Does it have to be 600ohm on the primary or 10k on the primary?
Now I have 600ohm going to 10k and my commons sense is telling me it is wrong, and I should reverse it.
Should I?

I've used inductor on L1 positon. Should I ditch those and go with resistor as Bruno2000 suggested?

Huh... it's going to be a long week contemplating on it before I have a chance to try to get back to it and start debugging it...



Luka

 

[bruno2000]

My units are built following the SR1200's BOM but with one exception - I've used 1:2 edcors on both interstage and output. That's what I had around!

Now I'm wondering if I wired output transformer wrong way.
Does it have to be 600ohm on the primary or 10k on the primary?
Now I have 600ohm going to 10k and my commons sense is telling me it is wrong, and I should reverse it.
Should I?

I've used inductor on L1 positon. Should I ditch those and go with resistor as Bruno2000 suggested?

Huh... it's going to be a long week contemplating on it before I have a chance to try to get back to it and start debugging it...



Luka

Limited participation still for a bit, but I'll start here.
My objection to L1 as it's stated in the BOM is that the resistance is too high.  If you are going to feed a relatively low load, the voltage drop across L1 is too much, and the Voltage fed to the output section fluctuates a good bit.  If you use a resistor,  the filtering of the inductor is lost.  I wound my own inductors with #30 wire, and got the best of both worlds.
Best,
Bruno2000

 

[shot]

Limited participation still for a bit, but I'll start here.
My objection to L1 as it's stated in the BOM is that the resistance is too high.  If you are going to feed a relatively low load, the voltage drop across L1 is too much, and the Voltage fed to the output section fluctuates a good bit.  If you use a resistor,  the filtering of the inductor is lost.  I wound my own inductors with #30 wire, and got the best of both worlds.
Best,
Bruno2000

Bruno! I'm so glad you're back!

I have never wound an inductor. I feel I should understand them enough before rolling my own. Is it complicated?

I'm still out of town, like 500km far from my bedroom lab with pye still left on the table. I'll get back to it during the weekend and try to calibrate the chopper and see how it goes from there...

 

[shot]

Ok, I'm back to it!

I'm working on one channel. Though I have two, I still haven't got the enclosure to put them into, so this is still pcb with a bunch of wires sitting on my bedroom table. I haven't tested the second channel since I don't have space on the table. I would have to finish the first one.

I have adjusted the chopper to 250khz. All okay!

It seems that it is working almost correctly. I don't know!
The meter is working nice. Responds very nice. I don't have a scale in decibels for it, but it sits idle on 0.2mA when no GR is applied.
Switches seem to work okay. When switching ratios and limiter the needle on the meter bounces hard, but that I would say is normal since I saw on Abe's video it is doing the same.
Ratio, Limit and Decay seem to behave as they sould.

But first what I notice is that the noise is very high. I haven't measured it, but it is very noticable. Could that be due to the fact that this isn't mounted in a metal enclosure? If I put my finger around the edge of ratio resistors (small pcb with lorlins) I make the buzzy part of the noise dissapear. It still has white noise component unchanged and it works normal.  I'm guessing this will dissapear once it is in metal box, right? But what about the rest of the noise?

When it starts compressing the signal, on the first few milliseconds of the attack, it has a noticeable THUMP added in the low end. I noticed that this happens when a large transient in the input signal comes in. This is especially noticeable when compressing vocal since the vocal sample I've used has no low end below 200hz.  It's not like like on dbx160VU when you have click on every transient due to the slow attack behavior. This is something added to the signal, and it doesn't sound right!

I haven't readjusted no trimmers yet. They are set in a position suggested in BOM before soldering.

What should I do next? How to get rid of the noise and this annoying thump on attacks?

I'll try to capture a video of it's behavior so you can see and hear for your self.
In the meantime, here's the photo just for fun!

 

[mdainsd]

Good to see progress!

Not sure about your noise issues, but.....

Your input transformer is not shielded and has longish unshielded wire runs.

The input pot (I see you are not using step attenuators?) also has long unshielded wire runs.

I wired mine using shielded twisted pairs about everywhere, power, attenuators basically everything except the wiring to the switch board.

Keep at it!

 

[desol]

I'll second the input transformer suggestion. I had the cheapish/unshielded edcor's on my D-la2a for the first bit and was noticing quite a lot of 60hz hum when I put it through a freq analyzer on the pc., from the onboard toroid.....so I decided to get into some original inputs and it made a huge difference. I'd definItely roll with the cinemag's on input as suggested, even if they are a few bucks.

 

[bruno2000]

Ok, I'm back to it!

I'm working on one channel. Though I have two, I still haven't got the enclosure to put them into, so this is still pcb with a bunch of wires sitting on my bedroom table. I haven't tested the second channel since I don't have space on the table. I would have to finish the first one.

I have adjusted the chopper to 250khz. All okay!

It seems that it is working almost correctly. I don't know!
The meter is working nice. Responds very nice. I don't have a scale in decibels for it, but it sits idle on 0.2mA when no GR is applied.
Switches seem to work okay. When switching ratios and limiter the needle on the meter bounces hard, but that I would say is normal since I saw on Abe's video it is doing the same.
Ratio, Limit and Decay seem to behave as they sould.

But first what I notice is that the noise is very high. I haven't measured it, but it is very noticable. Could that be due to the fact that this isn't mounted in a metal enclosure? If I put my finger around the edge of ratio resistors (small pcb with lorlins) I make the buzzy part of the noise dissapear. It still has white noise component unchanged and it works normal.  I'm guessing this will dissapear once it is in metal box, right? But what about the rest of the noise?

When it starts compressing the signal, on the first few milliseconds of the attack, it has a noticeable THUMP added in the low end. I noticed that this happens when a large transient in the input signal comes in. This is especially noticeable when compressing vocal since the vocal sample I've used has no low end below 200hz.  It's not like like on dbx160VU when you have click on every transient due to the slow attack behavior. This is something added to the signal, and it doesn't sound right!

I haven't readjusted no trimmers yet. They are set in a position suggested in BOM before soldering.

What should I do next? How to get rid of the noise and this annoying thump on attacks?

I'll try to capture a video of it's behavior so you can see and hear for your self.
In the meantime, here's the photo just for fun!

Shield everything.  I have to turn off my cell phone to test on bench.
Edcor open frame inputs won't do.  Get the Cinemags or equal.  Maybe some old British inputs.
My $0.02, but maybe that's too much to pay.........

 

[shot]

Hey guys! Thanks for the help!

I'll change all those wires to shielded ones as soon as I move those boards into an enclosure!
And when I do that, should I tie the ground (screen) of the cable to the earth or to B+ ??

I'm on the cheap side with transformers unfortunately. It would be too expensive for me to get cinemags all around, but what I'll do is to wrap all the transformers in copper foil and bend a piece of sheet metal around them. That way they will be double shielded - metal enclosure will shield everything plus sheet metal will shield transformers. That should help I guess...

But that still leaves me with a bigger problem and that is those ugly thumps on the attack.
I've wired the second board (still using the same wires from the first one - so noise is present in the same amount) and went to see what's happening on that board. Just the same! Attack thumps and behaves just as the first board! Must be some wrong component they both have in common. Those two channels were built with every component exactly the same. I was stuffing them simultaneously and checking with DMM everything twice, so no wonder they act the same...

Here's the video I've uploaded to show you how it sounds and what those thumps are.
The noise in the background is all from the unit. It's not camera noise!
But I'll fix that noise with your advices!

https://www.youtube.com/watch?v=j6FHFdfSGxA

You may notice that thumps are in relation with the ratio. On 2:1 (not in the video) they are almost non-existant. On 5:1 they are severe and on 3:1 there are some.

It's saturday. I'll have to rush to buy me an enclosure asap today, not too loose the weekend work! I know where to get a nice one!

 

[tommia]

another mistake is R70. It is not 11K but 11k parallel to  a 20k resistor resulting in 7k1.  This will improve the feel of the ratio.
You could use 1k5 in series with 5k6.

Attack problems: turn R52 clockwise

 

[shot]

Thanks! I'll try the R52 trimmer to see if it helps!

If you follow the pcb silkscreen or Abe's build buttler, you'll notice that R70 is 6K8.
I don't know why is it labeled 6k8 (11K) on the schematic...
I've installed 6k8...

 

[shot]

I've tried changing the value of R52. It indeed has something to do with the speed of the attack. It almost removed the thump from the attacks, but I'm not sure how it affected the release times. I don't mind if release also drifts a bit, but I'll have to measure it if it went off too much.
Also, when changing R52, zero GR spot on the meter moves towards 0.4mA. If I get attacks to behave acceptable, I'll deal with this later...
But I'm moving in a good direction.

I have wrapped edcor transformers with self-adhesive copper foil I had bought long ago on ebay. Wasn't expecting any change, but it actually dropped the noise a bit! I believe when I put all of it in the metal enclosure it will drop to an acceptable level.

I've bought the enclosure yesterday but I'm not sure if my two units will fit onto the 2H front panel since I have huge meters.
I haven't put the boards inside the case yet. Had no time (weekends are not what they used to be...).