PYE Compressor/Limiter Thread *boards shipping* BOM up!
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thetawaves
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I unwrapped one winding on the transformer I built to raise the frequency.
Then also added a 100pF capacitor in parallel with the 0.001 cap to fine tune.
It is now right at 250KHz with some adjustment of the tuning slug.
Then also added a 100pF capacitor in parallel with the 0.001 cap to fine tune.
It is now right at 250KHz with some adjustment of the tuning slug.
Hi, I could finish my Pie! It is working perfectly. Fanstic sounding piece. The killer on drums. Works nearly always on each drumtrack. Wow. So transparent, crystal clear, "ultrapushy", gentle.... Thanks Abe, thanks Rob Flinn, thanks to Igors UTM/IGS Transformers, thanks Frank Roellen!
One of the best builds I ve ever done, the audioquality is nearly unbeatable good...
One of the best builds I ve ever done, the audioquality is nearly unbeatable good...
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I have used UTM Transformers from Polska for the build. They are fantastic.
-As Input TX T1 I used the 2571 -> 10K/10K Ohm 1:1. That means primary and secondary winding in series connected and wired via cabels instead of the suggested Cinemag.
-Output TX used the 3515 -> as STEPUP! 600/15KOhm 1:5, red*/or to board XLR, outpads Yel*/Grn over Relaybypassboard to XLR Out connection to pin 2+3
-Sidchain TX T4 - I used the 2546 -> as stepup configuration 600/10kohm 1:4, 600Ohm Side is parallel, 10k side is serial, look at two pictures for my used connection, others ratios did not work for my build
-As Input TX T1 I used the 2571 -> 10K/10K Ohm 1:1. That means primary and secondary winding in series connected and wired via cabels instead of the suggested Cinemag.
-Output TX used the 3515 -> as STEPUP! 600/15KOhm 1:5, red*/or to board XLR, outpads Yel*/Grn over Relaybypassboard to XLR Out connection to pin 2+3
-Sidchain TX T4 - I used the 2546 -> as stepup configuration 600/10kohm 1:4, 600Ohm Side is parallel, 10k side is serial, look at two pictures for my used connection, others ratios did not work for my build
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Some things to mention:
- I ve used a cheap 8 Pole Relayboard, triggervoltage is switched on one pole of the Lorlin 4P3T for Bypass/On/Off, Powersupply L/N on two other poles - the current is very low, far under the "allowed" 150 mA for Lorlins, the LM337 stay also nearly cold
-I am using for as TR11 Fairchilds 2N3640 from an Italian electronic shop in Roma, real "Bellas"
-My PSU Voltage for the boards is -20,0V DC, the first thing I ve adjusted / with VR1 Trimmer, measured between the B+/B- Pads, my Powersupply is a 24V AC Terroid (12V+12V) with 1A from Triad
-then I adjusted the Oszilators to about 250kHz with my cheap Multimeter, it was total easy, look at my pictures, take the Ground/Mass and the left lower Pin and adjust with the Oszillator-onboard Trimmer to 250kHz, no problem with this adjustment
-set the unitiy gain, I recommend to install pinholders for TR11- taken from a cheap IC Socket and soldered these pinholder directly on the boards, you need to remove TR11 to do that calibration and so its much easier doing that, then I adjusted the Input and Gainpots to 12 o'clock, insert a voltage of about 0dB 0,775V 1khz Sine, measure between pin 2+3 XLR on In and Out Connections , and adjusted with R23 till unity gain on the Output 2+3 XLR Pins, like in Abes build notes,
-R44 500k was set to about 220k before soldering - set, solder and forget...
-as for the starting point of the threshold I did the same as mentioned in Abes Pye build notes, Inputpot fully clockwise, added a 1khz Sine with about 0.049V AC measured between Pin2+3 on Input Conections,
Then set the Multimeter to DC, measure on the right end of R50 / Square-solderpad - in my case I measured about -0,82V DC, turning the R52 Trimmer shows after a few turns a point, where the Voltage started to drop from this -0,82V DC, also my used Gainreduction SSL Clone 8027 Meters from Franks Fronpanels.de made a small move up and start at this point to rise, I set this Voltagedrop only minimal to about -0,80V DC as starting point on both Channels, then I set the Meter-Zere through adding/soldering a second 220 Ohm resistor in parallel over the R67 1K Ohm. It is also possible that you need another Value for R67 to get the "Zero" like a 300 Ohm .... You also can add here Pinholders and play around with other resistor, or a Trimmer.....
For R48 I did not change the standard 1K5 Resistor from the BOM, after a minimal of bit mechanical zero with the screw on the meters I really got the "0"
-then I increased the signallevel "external" on the signalgenerator without changing any Input-Pot to -4dBu to about 0,49 V AC - measured on Pin 2+3 Input XLR Connection -> that means +20dB increasment from -24dBu to -4dBu, checked a 4:1 Ratio on the frontpanel and then adjusted with the R42 Trimmer a Gainreduction of about -15dB shown on the GR-Meters, then rechecked the Gainreduction with 3:1 Ratio to about -13db shown on the Meters and readjusted a little bit with R42 Trimmer if necessary, on 2:1 to about -10dB Gainreduction on the meters and readjusted...repeat all more times...., its a compromise between all ratios and both channels, I set this adjustments as good as possible and it works pretty very well,....
-> the calbration is similar to Fet 1176 Comps
That's it
- I ve used a cheap 8 Pole Relayboard, triggervoltage is switched on one pole of the Lorlin 4P3T for Bypass/On/Off, Powersupply L/N on two other poles - the current is very low, far under the "allowed" 150 mA for Lorlins, the LM337 stay also nearly cold
-I am using for as TR11 Fairchilds 2N3640 from an Italian electronic shop in Roma, real "Bellas"
-My PSU Voltage for the boards is -20,0V DC, the first thing I ve adjusted / with VR1 Trimmer, measured between the B+/B- Pads, my Powersupply is a 24V AC Terroid (12V+12V) with 1A from Triad
-then I adjusted the Oszilators to about 250kHz with my cheap Multimeter, it was total easy, look at my pictures, take the Ground/Mass and the left lower Pin and adjust with the Oszillator-onboard Trimmer to 250kHz, no problem with this adjustment
-set the unitiy gain, I recommend to install pinholders for TR11- taken from a cheap IC Socket and soldered these pinholder directly on the boards, you need to remove TR11 to do that calibration and so its much easier doing that, then I adjusted the Input and Gainpots to 12 o'clock, insert a voltage of about 0dB 0,775V 1khz Sine, measure between pin 2+3 XLR on In and Out Connections , and adjusted with R23 till unity gain on the Output 2+3 XLR Pins, like in Abes build notes,
-R44 500k was set to about 220k before soldering - set, solder and forget...
-as for the starting point of the threshold I did the same as mentioned in Abes Pye build notes, Inputpot fully clockwise, added a 1khz Sine with about 0.049V AC measured between Pin2+3 on Input Conections,
Then set the Multimeter to DC, measure on the right end of R50 / Square-solderpad - in my case I measured about -0,82V DC, turning the R52 Trimmer shows after a few turns a point, where the Voltage started to drop from this -0,82V DC, also my used Gainreduction SSL Clone 8027 Meters from Franks Fronpanels.de made a small move up and start at this point to rise, I set this Voltagedrop only minimal to about -0,80V DC as starting point on both Channels, then I set the Meter-Zere through adding/soldering a second 220 Ohm resistor in parallel over the R67 1K Ohm. It is also possible that you need another Value for R67 to get the "Zero" like a 300 Ohm .... You also can add here Pinholders and play around with other resistor, or a Trimmer.....
For R48 I did not change the standard 1K5 Resistor from the BOM, after a minimal of bit mechanical zero with the screw on the meters I really got the "0"
-then I increased the signallevel "external" on the signalgenerator without changing any Input-Pot to -4dBu to about 0,49 V AC - measured on Pin 2+3 Input XLR Connection -> that means +20dB increasment from -24dBu to -4dBu, checked a 4:1 Ratio on the frontpanel and then adjusted with the R42 Trimmer a Gainreduction of about -15dB shown on the GR-Meters, then rechecked the Gainreduction with 3:1 Ratio to about -13db shown on the Meters and readjusted a little bit with R42 Trimmer if necessary, on 2:1 to about -10dB Gainreduction on the meters and readjusted...repeat all more times...., its a compromise between all ratios and both channels, I set this adjustments as good as possible and it works pretty very well,....
-> the calbration is similar to Fet 1176 CompsThat's it
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Fsharpminor
Active member
- Joined
- May 4, 2015
- Messages
- 41
HOLY COW THANK YOU THANK YOU! Thats the info I needed!
In various posts in this thread it is assumed that R52 controls the Decay time. I'm interested to know the thinking behind the DC voltage drop to set decay time? As Abes notes say this sets threshold?!
It is also suggested that R52 may "may not work correctly with 555 oscillator." I'm planing on building the ferrite core oscillator and see how this effect setup. Anyone have experience with chip VS ferrite?
This was my statement. I wrote what I found when compared 555 vs inductor oscillator. My conclusion was 555 oscillator is too "stiff" and doesn't behave the same way as the discrete one.
If you do your own set of comparisons, it would be very interesting to know what you find.
Hi, the "Pye Build Notes" are okay. Only the 0.25V DC Drop on R52 for setting the " Starting Threshold/Bias Point" was in my opinion to much, what I can remind setting up my Unit. Setting the VU Meter was also a little bit different. I wrote all things about the calibration and that should work fine using the same components, transformers/ratios, oszillator.... The PCBs work perfectly, nothing wrong. You should get a really fantastic sounding Compressor, one of the best ever designed ...
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What ratio transformers did you use to drive the sidechain?
Hi, I used an UTM 2546 600/10K. Ratio 1:4. Other Ratios did not work, wrong Range.
Read Post 1124 in the thread....Regards
Compressor sounds great. I have this for years. however never really understood how this sets ups.Hi, the "Pye Build Notes" are okay. Only the 0.25V DC Drop on R52 for setting the " Starting Threshold/Bias Point" was in my opinion to much, what I can remind setting up my Unit. Setting the VU Meter was also a little bit different. I wrote all things about the calibration and that should work fine using the same components, transformers/ratios, oszillator.... The PCBs work perfectly, nothing wrong. You should get a really fantastic sounding Compressor, one of the best ever designed ...
Anyone got a scope screen shot of the TLC555 waveform? I get downward spikes that are not that stable in frequency. I didn't screen grab at the time!
skal1
Well-known member
Hi lad i think i am going to jump on this , i have a few ?
where do i get T3 , what is it , did you lad go with the bc560c/bc550a or the Orignal part numbers
any help would be good
cheers
Skla1
1}
where do i get T3 , what is it , did you lad go with the bc560c/bc550a or the Orignal part numbers
any help would be good
cheers
Skla1
1}
Here are a few detailed Photos of the unit. I used "standard" BC550/60 C's. I have soldered sockets to test more expensive transistor on TR 12, 16 and 18. But specially for TR11 it is necessary to remove TR11 for Calibration!
All important infos are in the Thread and in the instructions. It is a lot to read, I know.
All important infos are in the Thread and in the instructions. It is a lot to read, I know.
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You need this. If you want to use UTM Transformers from Igor / IGS then you can use the transformers from post 1124. There is also the used transformer ratio described for T1 Input, T3 Output and T4 Sidechain TX. T2 should be the Power Transformer
Greetz
Greetz
The general consensus is to remove TR11 to set unity gain. This removes the side chain from the audio path. This means that you can set the audio paths to unity.
However the side chain circuits may effect gain differently when you are on 1.1. I had issues with the chip oscillator circuit behaving differently between two units and I could not dial it in. I've been looking at lots of pye guts images and using other info on this thread just wound my own oscillator.
As Ilya as mentioned throughout this thread and also given some detail on I agree with his conclusion of the following.
- Meter will line up properly with the an inductor oscillator no mods needed to resistor values.
- The side chain works differently with an inductor oscillator. The chip works but it does not sound the same. It is a great sounding compressor but in my opinion not as true to the original.
- Abe mentioned somewhere that lining up two units was easier with chip based oscillator. For me the opposite is true.
I haven't fully lined up my units yet as I broke a leg on TR11 while removing from socket. I'm waiting for replacements. Once I have played around a little more I will post full details.
I'd love to get a copy of the original service manual. I have found one for sale but it is $35 anyone interested in a group buy and I will scan and upload the document?
Don’t bother with the service manual. It doesn’t have any info regarding blocking oscillator inductor and AOT components. If you do decide to buy this paper, ask a seller if this manual actually has the info you need. If it does, I’m ready to split the cost.
Hi, I dont have an original analog old one and have never worked with one. So I can only compare it to a plug in. They are really close! The plug in does a little bit more static harsh thing in the highs. But this fantastic pushy thing, especially on snares, is very similar. The impact of the analog unit is more fatter, broader, does a more "musical integrative" thing. The plug is also nice but more boring.
Abe's instructions are working well on the most settings. They make sense. Things like Meter setting and starting Point of the Threshold are not perfectly written down there.
I can also recommend to take care with the transistor legs and directions (look at my pictures,...), use the correct ratios of the transformers, or it is not able to do a calibration of the compressor because it playes in the wrong ballpark - that is what I experienced at my first starting tests. Setting the correct starting point was also very important or this piece sounds a little bit nasty.
If an inductive "chopper" Oszillator can give an additional improvement,
"more original", I dont know. But for sure it is worth to try it, why not. But nevertheless I think the TI TLC555CP Oszillators are easy, cheap, and they work great in the build..
Sorry for the bad quality of the comparison
Abe's instructions are working well on the most settings. They make sense. Things like Meter setting and starting Point of the Threshold are not perfectly written down there.
I can also recommend to take care with the transistor legs and directions (look at my pictures,...), use the correct ratios of the transformers, or it is not able to do a calibration of the compressor because it playes in the wrong ballpark - that is what I experienced at my first starting tests. Setting the correct starting point was also very important or this piece sounds a little bit nasty.
If an inductive "chopper" Oszillator can give an additional improvement,
"more original", I dont know. But for sure it is worth to try it, why not. But nevertheless I think the TI TLC555CP Oszillators are easy, cheap, and they work great in the build..
Sorry for the bad quality of the comparison
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The inductors look like Carnhill which would make sense as they are both British manufactures also supplied the likes of Neve. Potentially custom wound for PYE or off the shelf long discontinued.
Are you referring to the variable resistors as AOT's. I'm not familiar with this term?
On the original from pictures and quickly scanning the schematics it seems there is only one variable resistor. That would be R41 1K marked as Decay. I believe this would be the equivalent ABE's R52 1K. The 10K trim R42 on ABE's is the equvilant of the fixed R41 5K1 fixed on the original. So I would conclude the original only has one adjustable trim pot for setup.
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