TG1 - advice from any one who has built it...

[trampo]

Are you getting unity gain with the compressor in?

I have managed to get mine to work at unity gain by lowering the value of R19 and R21, the downside is it now does not follow the voltages written on the original schematic.

Not sure if I am boosting earlier on in the circuit to make up for loses later on?

A friend of mine worked out that the impedance of the diodes would cause this to happen, maybe different batches of diodes would not need this mod.

However the unit now works as you would expect and sounds fantastic.

Trampo

 

[bruno2000]

Are you getting unity gain with the compressor in?

I have managed to get mine to work at unity gain by lowering the value of R19 and R21, the downside is it now does not follow the voltages written on the original schematic.

Not sure if I am boosting earlier on in the circuit to make up for loses later on?

A friend of mine worked out that the impedance of the diodes would cause this to happen, maybe different batches of diodes would not need this mod.

However the unit now works as you would expect and sounds fantastic.

Trampo

Thanks for the suggestion! 
My situation is that in the sidechain OUT (THD position), I cannot get unity gain through the unit with the HOLD control at mid position.  I am using a 10k linear switch, with R115 (?) shorted out.  From the input to the output it's about 15 dB down. 
The output section is giving me the appropriate 14dB of gain with the output switch centered, so that's not the issue
If I raise the value of AOT1 to 3k9, increasing the CV, I can get unity, but then the metering is messed up.
Lowering the values of R21 and R23 does pretty much the same thing from a different side, although I don't know what it would do to the metering.
This weekend I am going to try some different brand Zeners (D1, D2, D3, D4) and see what change that makes.
I think that it's really interesting that some folks have gotten their units to work well, but others have this gain loss problem.
Please chime in if you have thoughts or suggestions!
Thanks!
Best,
Bruno2000
Anyone else out there have suggestions?

 

[jplebre]

no but im really interested if you do find anything

 

[muffy1975]

Guys,


i'm trying to match some zeners for the TG .


I am using this JIG and 1n751 diodes.

Am i looking for four diodes with the same voltage when switched  between 1K and 50K or just four that react in the same way?

Hope you can help me here.

Thanks in advance

Michael

 

[late]

I am almost ready with my tg1 but second channel have distortion. Anyone have an idea what can do this?

Sample:
https://dl.dropboxusercontent.com/u/20579799/TG1.wav

 

[muffy1975]

Does the poormans variant work as described here?

Me thinks not.

I can't get the relays to switch over. Omron 24V 1A G5V-2-1H

The LED is on when in bypass ( position on the switch ) and the LED is off when IN???

Getting +/-24V. getting all the correct voltages arouns the two pcbs.

If i hard wired the 604 to the input xlr and hardwire the output of the main pcb i get the unit working and compressing.

Just can't get the I/O board and its relays to work.

Is the in out switch supposed to be a spdt as stated?


Anyone know about this?


Michael

 

[trampo]

Ok so I have now built both the original rack version and the 500 series version with slightly different results.

The rack version I used all original components including the hs2051 diodes and have low output, about 6dB down, which isn't to much of an issue if I wire the output transformers to +6dB.

The 500 series is from Igors kit and I can get unity gain with no problem.

So far the only differences I can see are:-

A0202s are H333
BCY 71 and BC109 are the BC184 and 214s
2.4mA meter with the 1mA and compensation circuit
hs2051 with 1n751 diodes

In theory none of the above should make much of a difference, however I with a number of others are experiencing low output on the rack version.

If anyone has any suggestions as to any measurements or comparisons I could make between the 2 units we may be able to get to the bottom of the issue.

Trampo 

 

[bruno2000]

Ok so I have now built both the original rack version and the 500 series version with slightly different results.

The rack version I used all original components including the hs2051 diodes and have low output, about 6dB down, which isn't to much of an issue if I wire the output transformers to +6dB.

The 500 series is from Igors kit and I can get unity gain with no problem.

So far the only differences I can see are:-

A0202s are H333
BCY 71 and BC109 are the BC184 and 214s
2.4mA meter with the 1mA and compensation circuit
hs2051 with 1n751 diodes

In theory none of the above should make much of a difference, however I with a number of others are experiencing low output on the rack version.

If anyone has any suggestions as to any measurements or comparisons I could make between the 2 units we may be able to get to the bottom of the issue.

Trampo

I am doing some extensive testing of my TG units to try and figure out this gain issue that a lot of us are having.  It would help me a great deal if you could measure the current that the meter is measuring.  Just put a DVM on its 2mA current range IN SERIES with the meter and its conversion network.  What I'm interested in is that value with NO INPUT SIGNAL, and the HOLD switch / pot in the center, and at each extreme.  I also need to know if you used the 10k linear, or the 5k r/log pot plus the 5k resistor on the board for the hold control.
Thanks so much for any reply.  I hope to have a fix soon.
Best,
Bruno2000

 

[trampo]

Ok so I have now built both the original rack version and the 500 series version with slightly different results.

The rack version I used all original components including the hs2051 diodes and have low output, about 6dB down, which isn't to much of an issue if I wire the output transformers to +6dB.

The 500 series is from Igors kit and I can get unity gain with no problem.

So far the only differences I can see are:-

A0202s are H333
BCY 71 and BC109 are the BC184 and 214s
2.4mA meter with the 1mA and compensation circuit
hs2051 with 1n751 diodes

In theory none of the above should make much of a difference, however I with a number of others are experiencing low output on the rack version.

If anyone has any suggestions as to any measurements or comparisons I could make between the 2 units we may be able to get to the bottom of the issue.

Trampo

I am doing some extensive testing of my TG units to try and figure out this gain issue that a lot of us are having.  It would help me a great deal if you could measure the current that the meter is measuring.  Just put a DVM on its 2mA current range IN SERIES with the meter and its conversion network.  What I'm interested in is that value with NO INPUT SIGNAL, and the HOLD switch / pot in the center, and at each extreme.  I also need to know if you used the 10k linear, or the 5k r/log pot plus the 5k resistor on the board for the hold control.
Thanks so much for any reply.  I hope to have a fix soon.
Best,
Bruno2000

I am using the 10K linear pot in both cases.

I will have at look at this over the weekend and post the results as soon as i have them.

Also one thing I have noticed is that the sintech meters have 0 in the center, however the original EMIs have 0 slightly offset and Igor quotes "Set unity gain with AOT1 trimpot; meter reading should show 0db (55% of full scale).
For differerent meters types scale can be different.
If needed, move a bit HOLD pot."

Trampo

 

[bruno2000]

Ok so I have now built both the original rack version and the 500 series version with slightly different results.

The rack version I used all original components including the hs2051 diodes and have low output, about 6dB down, which isn't to much of an issue if I wire the output transformers to +6dB.

The 500 series is from Igors kit and I can get unity gain with no problem.

So far the only differences I can see are:-

A0202s are H333
BCY 71 and BC109 are the BC184 and 214s
2.4mA meter with the 1mA and compensation circuit
hs2051 with 1n751 diodes

In theory none of the above should make much of a difference, however I with a number of others are experiencing low output on the rack version.

If anyone has any suggestions as to any measurements or comparisons I could make between the 2 units we may be able to get to the bottom of the issue.

Trampo

I am doing some extensive testing of my TG units to try and figure out this gain issue that a lot of us are having.  It would help me a great deal if you could measure the current that the meter is measuring.  Just put a DVM on its 2mA current range IN SERIES with the meter and its conversion network.  What I'm interested in is that value with NO INPUT SIGNAL, and the HOLD switch / pot in the center, and at each extreme.  I also need to know if you used the 10k linear, or the 5k r/log pot plus the 5k resistor on the board for the hold control.
Thanks so much for any reply.  I hope to have a fix soon.
Best,
Bruno2000

I am using the 10K linear pot in both cases.

I will have at look at this over the weekend and post the results as soon as i have them.

Also one thing I have noticed is that the sintech meters have 0 in the center, however the original EMIs have 0 slightly offset and Igor quotes "Set unity gain with AOT1 trimpot; meter reading should show 0db (55% of full scale).
For differerent meters types scale can be different.
If needed, move a bit HOLD pot."

Trampo

Yes, I noticed the slight issue with the meter, but the question is the actual current going through the diodes, and how to achieve the gain appropriate structure.  I have one channel with modern high hfe transistors, and a second with "vintage" low to medium hfe.  Both channels measure about the same current, and they both have the same gain issue using the 1N751 diodes.
Thanks for your time to do measurements!
Best,
Bruno2000

 

[Winetree]

Ok so I have now built both the original rack version and the 500 series version with slightly different results.

Trampo, Are you talking about Igor's TG-500 series compressor?

 

[trampo]

Ok so I have now built both the original rack version and the 500 series version with slightly different results.

Trampo, Are you talking about Igor's TG-500 series compressor?

Yes, it is the full kit including all components.

 

[trampo]

Ok so I have now built both the original rack version and the 500 series version with slightly different results.

The rack version I used all original components including the hs2051 diodes and have low output, about 6dB down, which isn't to much of an issue if I wire the output transformers to +6dB.

The 500 series is from Igors kit and I can get unity gain with no problem.

So far the only differences I can see are:-

A0202s are H333
BCY 71 and BC109 are the BC184 and 214s
2.4mA meter with the 1mA and compensation circuit
hs2051 with 1n751 diodes

In theory none of the above should make much of a difference, however I with a number of others are experiencing low output on the rack version.

If anyone has any suggestions as to any measurements or comparisons I could make between the 2 units we may be able to get to the bottom of the issue.

Trampo

I am doing some extensive testing of my TG units to try and figure out this gain issue that a lot of us are having.  It would help me a great deal if you could measure the current that the meter is measuring.  Just put a DVM on its 2mA current range IN SERIES with the meter and its conversion network.  What I'm interested in is that value with NO INPUT SIGNAL, and the HOLD switch / pot in the center, and at each extreme.  I also need to know if you used the 10k linear, or the 5k r/log pot plus the 5k resistor on the board for the hold control.
Thanks so much for any reply.  I hope to have a fix soon.
Best,
Bruno2000

I am using the 10K linear pot in both cases.

I will have at look at this over the weekend and post the results as soon as i have them.

Also one thing I have noticed is that the sintech meters have 0 in the center, however the original EMIs have 0 slightly offset and Igor quotes "Set unity gain with AOT1 trimpot; meter reading should show 0db (55% of full scale).
For differerent meters types scale can be different.
If needed, move a bit HOLD pot."

Trampo

Yes, I noticed the slight issue with the meter, but the question is the actual current going through the diodes, and how to achieve the gain appropriate structure.  I have one channel with modern high hfe transistors, and a second with "vintage" low to medium hfe.  Both channels measure about the same current, and they both have the same gain issue using the 1N751 diodes.
Thanks for your time to do measurements!
Best,
Bruno2000

Here are some initial measurements:-

Rack version 0 (center) 1.2mA going down to 0 and up to 3.6mA (with sintech meter)
If i then plug the same meter into the 500 series version (and remove the extra pot and resistor) I get the same results with the current but this does not effect the gain.
I have 2 other 1mA full scale meters and the results vary in terms of current and therefore alignment but does not affect the gain.
Not sure this sheds anymore light on the problem!
Let me know what else to measure, I have both units here and would like to help in solving this problem.

Regards

Trampo

 

[bruno2000]

Ok so I have now built both the original rack version and the 500 series version with slightly different results.

The rack version I used all original components including the hs2051 diodes and have low output, about 6dB down, which isn't to much of an issue if I wire the output transformers to +6dB.

The 500 series is from Igors kit and I can get unity gain with no problem.

So far the only differences I can see are:-

A0202s are H333
BCY 71 and BC109 are the BC184 and 214s
2.4mA meter with the 1mA and compensation circuit
hs2051 with 1n751 diodes

In theory none of the above should make much of a difference, however I with a number of others are experiencing low output on the rack version.

If anyone has any suggestions as to any measurements or comparisons I could make between the 2 units we may be able to get to the bottom of the issue.

Trampo

I am doing some extensive testing of my TG units to try and figure out this gain issue that a lot of us are having.  It would help me a great deal if you could measure the current that the meter is measuring.  Just put a DVM on its 2mA current range IN SERIES with the meter and its conversion network.  What I'm interested in is that value with NO INPUT SIGNAL, and the HOLD switch / pot in the center, and at each extreme.  I also need to know if you used the 10k linear, or the 5k r/log pot plus the 5k resistor on the board for the hold control.
Thanks so much for any reply.  I hope to have a fix soon.
Best,
Bruno2000

I am using the 10K linear pot in both cases.

I will have at look at this over the weekend and post the results as soon as i have them.

Also one thing I have noticed is that the sintech meters have 0 in the center, however the original EMIs have 0 slightly offset and Igor quotes "Set unity gain with AOT1 trimpot; meter reading should show 0db (55% of full scale).
For differerent meters types scale can be different.
If needed, move a bit HOLD pot."

Trampo

Yes, I noticed the slight issue with the meter, but the question is the actual current going through the diodes, and how to achieve the gain appropriate structure.  I have one channel with modern high hfe transistors, and a second with "vintage" low to medium hfe.  Both channels measure about the same current, and they both have the same gain issue using the 1N751 diodes.
Thanks for your time to do measurements!
Best,
Bruno2000

Here are some initial measurements:-

Rack version 0 (center) 1.2mA going down to 0 and up to 3.6mA (with sintech meter)
If i then plug the same meter into the 500 series version (and remove the extra pot and resistor) I get the same results with the current but this does not effect the gain.
I have 2 other 1mA full scale meters and the results vary in terms of current and therefore alignment but does not affect the gain.
Not sure this sheds anymore light on the problem!
Let me know what else to measure, I have both units here and would like to help in solving this problem.

Regards

Trampo

Current through the meter should equate to a change in gain. 
Attached is a chart of my measurements for one channel.  The other channel is almost identical.  Measurements taken with 1N751 diodes, batch #1.

 

[bruno2000]

Here's my test setup.
Cell phone camera, ugh!
Best,
Bruno2000

 

[trampo]

Attached are the measurements from both my rack version and my 500series version. Whilst testing I noticed a difference between the units at test point H, so I have included these with both the DC and AC voltages at point H.

Hope this helps

Trampo

 

[bruno2000]

Attached are the measurements from both my rack version and my 500series version. Whilst testing I noticed a difference between the units at test point H, so I have included these with both the DC and AC voltages at point H.

Hope this helps

Trampo

Nice, thank you!  I'll study this.  You said test point H, do you mean test point E?
Best,
Bruno2000

 

[trampo]

Apologies, yes I did mean test point E, also it was with compression in.

Trampo

 

[trampo]

I have taken the sidechain from the 500 series and wired it into the rack version and I can now achieve unity gain on the rack version!

The next thing to try is hard wiring the hold and all font panel controls to see if we have another problem with the front panel pcb.

Has any one got any thoughts on Hfe gain of the transistors?

Any other suggestions welcomed.

Trampo

 

[bruno2000]

I have taken the sidechain from the 500 series and wired it into the rack version and I can now achieve unity gain on the rack version!

The next thing to try is hard wiring the hold and all font panel controls to see if we have another problem with the front panel pcb.

Has any one got any thoughts on Hfe gain of the transistors?

Any other suggestions welcomed.

Trampo

Hoping to study your data this weekend. 
What Zener diodes are you using?
Thanks!
Best,
Bruno2000