Check the projects docs, there's much more to it.Hank Dussen said:
For me it took longer to get the calibration about right than any other project I've built (incl. the 760 which has quite a time consuming calibration).
TG1 - advice from any one who has built it...
- Thread starter mathsieve
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Help Support GroupDIY Audio Forum:
For me it took longer to get the calibration about right than any other project I've built (incl. the 760 which has quite a time consuming calibration).
Hank Dussen
Well-known member
These are the only 'calibration'-notes I can find:
Testproc:
1). +/-20v
JP1...6, TP+20v, TP-20v
2).Unity gain
Initial gain is set by AOT1,2
3).Distortion w/o compression
minimum distortion adjustment AOT 7,9
4).Distortion at 20dB GR
distortion under hard compression adjusted by AOT8/10, usually 10R is fine
5).Com threshold
Com threshold adjustment: AOT3,4
6).Lim threshold
Lim threshold set by AOT5,6.
7).Check: reqresp, max gain, min gain, S/N, timeconstants.
but most guys here seem to go with the standard AOT-resistors tough.
Am I missing something here?
It would be really helpful if people gave me some directions concerning, for example, the compression and limiter threshold adjustment.
How did you calibrate yours?
Also, what changes should I make if I want to use the meter in the Chandler way, showing gain-reduction?
Testproc:
1). +/-20v
JP1...6, TP+20v, TP-20v
2).Unity gain
Initial gain is set by AOT1,2
3).Distortion w/o compression
minimum distortion adjustment AOT 7,9
4).Distortion at 20dB GR
distortion under hard compression adjusted by AOT8/10, usually 10R is fine
5).Com threshold
Com threshold adjustment: AOT3,4
6).Lim threshold
Lim threshold set by AOT5,6.
7).Check: reqresp, max gain, min gain, S/N, timeconstants.
but most guys here seem to go with the standard AOT-resistors tough.
Am I missing something here?
It would be really helpful if people gave me some directions concerning, for example, the compression and limiter threshold adjustment.
How did you calibrate yours?
Also, what changes should I make if I want to use the meter in the Chandler way, showing gain-reduction?
I found the 'basic' calibration was pretty easy, but the real challenge was to get two units matched as closely as possible for stereo operation. Especially the distortion adjustments complicated the calibration.
Btw, I used multiturn trimmers for all AOT resistors in an effort to get best possible stereo tracking. The best stereo matching I could reach is about 0,5db (when compressing 0-20db).
I can't really describe the procedure much, because it was like adjusting a trimmer here and then adjusting another, then getting back to adjust the other...
For a mono unit the calibration may not be that time consuming at all.
Btw, I used multiturn trimmers for all AOT resistors in an effort to get best possible stereo tracking. The best stereo matching I could reach is about 0,5db (when compressing 0-20db).
I can't really describe the procedure much, because it was like adjusting a trimmer here and then adjusting another, then getting back to adjust the other...
For a mono unit the calibration may not be that time consuming at all.
ChuckD
Well-known member
I have an issue with one side of my TG1
Here are the clues....
It passes audio. Although not totally clean I do not believe
Also when I disengage THD thus putting VT14 back into the circuit I get a complete DC voltage drop = 0V
Output signal drop out and the meter pegs for a moment.
The output signal and voltage recover BASED ON the RECOVERY TIME selection
With THD ON the circuit no longer compresses, at least the meter does not show any compression.
This also happens if I switch from Limit to Comp mode.
The output transistors all have proper DC levels
I Doubled checked all the transistors and diodes for proper component placement.
I checked most voltages vs the working side.
double checked the Limit, Comp switches as correct.
Any educated guesses out there??
Thanks in advance guys!
Chuck
Here are the clues....
It passes audio. Although not totally clean I do not believe
Also when I disengage THD thus putting VT14 back into the circuit I get a complete DC voltage drop = 0V
Output signal drop out and the meter pegs for a moment.
The output signal and voltage recover BASED ON the RECOVERY TIME selection
With THD ON the circuit no longer compresses, at least the meter does not show any compression.
This also happens if I switch from Limit to Comp mode.
The output transistors all have proper DC levels
I Doubled checked all the transistors and diodes for proper component placement.
I checked most voltages vs the working side.
double checked the Limit, Comp switches as correct.
Any educated guesses out there??
Thanks in advance guys!
Chuck
briomusic
Well-known member
Hi Chuck, the THD switch essentially disables the sidechain circuit, so you shouldn't be hearing or seeing any compression with THD on. with THD off (aka 'compressor IN') the meter moves to the preset voltage determined by the position of the 'hold' switch. the lowest preset voltage is at the highest 'hold' setting, and this is where you get the most compression 'swing'. It's the unique way this machine works, discussed at length earlier in the thread.
ChuckD
Well-known member
Hello Brio,
Thanks for your reply.
In my current configuration I have opted to ground out the Hold switch and use a Carnhill input transformer into an input pot. Same as Chandler does their TG1.
My problem is on one channel only in Limit Mode if the input signal is turned up suddenly it pegs the meter for an instant. Then the output signal craps out / cuts out and distorts then recovers.
This also seems to happen if a change modes from Limit to Comp and back again.
This does not occur on the other channel.
The hfe of VT13 and VT14 are matched now but it did not seem to fix this issue.
I have double checked the resistor values a fourth time but cannot find any problems.
The input signal level going to the side chain is the same for both sides.
I used BC184C and BC214C transistors everywhere except VT13/14 where I put matched non-"C" versions in last night.
Is it safe to assume the problem is definitely in the side chain?? I am assuming so.
Anyone with some thoughts?
I am a bit stumped
Chuck
Thanks for your reply.
In my current configuration I have opted to ground out the Hold switch and use a Carnhill input transformer into an input pot. Same as Chandler does their TG1.
My problem is on one channel only in Limit Mode if the input signal is turned up suddenly it pegs the meter for an instant. Then the output signal craps out / cuts out and distorts then recovers.
This also seems to happen if a change modes from Limit to Comp and back again.
This does not occur on the other channel.
The hfe of VT13 and VT14 are matched now but it did not seem to fix this issue.
I have double checked the resistor values a fourth time but cannot find any problems.
The input signal level going to the side chain is the same for both sides.
I used BC184C and BC214C transistors everywhere except VT13/14 where I put matched non-"C" versions in last night.
Is it safe to assume the problem is definitely in the side chain?? I am assuming so.
Anyone with some thoughts?
I am a bit stumped
Chuck
ChuckD
Well-known member
Guys,
CASH PRIZE to whomever can get me fixed! I would like to offer a cash prize to who ever can come up with a theory that in turn fixes the problem! I very much want this saga to end. Let's say 100 USD to the 1st guy who can get me fixed!
After replacing the entire Side Chain and all the input stage transistors the issue is still present on one channel.
Here is what I am seeing:
When the input signal hits a certain level 0.3 Vpp the whole circuit gets slammed. The DC voltages go crazy and the feedback loop causes the signal to clip. This only happens for a moment then the whole thing recovers.
The problem is inside the feedback loop as nothing strange happens to the signal when the side chain is either diconnected or the recovery switch is open. Or the THD is on. So it is safe to suggest that the amplifier is ok.
Normal reference DC Voltages taken from zero input signal to max input signal
VT15 (B = 0.8 to -1.33) (E= 0.545 to -0.165) (C= -20)
VT16 (B= 0.545) (E= 0) (C= 1.0 to 3.3)
VT17 (B= 1.0 to 3.3) (E= 0.5 to 2.8) (C= 18.26 to 17.97)
Broken
When the sidechain input hits 0.28 Vpp during that instant things get off
VT15 (B = -0.8) (E= -0.98) (C= -20)
VT16 (B= 0.430) (E= 0) (C= 4.0)
VT17 (B= 3.8) (E= 3.5) (C= 17.77)
If you continue past 0.28 Vpp the circuit does recover and acts as it should. DC voltages pretty much track the above reference.
I should also note that the circuit only does this peaky clip thing when coming from 0 up to 0.28 on the input of the side chain. Crossing 0.28 Vpp from a greater value does not cause it to ocurr again.
Another note is that the non-working side has a much higher swing in voltages on the collectors of VT2 and VT3. VT2 (C= -10.3 to -9.30) VT3 (C= -7.94 to -9.0)
The working side only has a 0.3VDC swing for each.
Chuck
CASH PRIZE to whomever can get me fixed! I would like to offer a cash prize to who ever can come up with a theory that in turn fixes the problem! I very much want this saga to end. Let's say 100 USD to the 1st guy who can get me fixed!
After replacing the entire Side Chain and all the input stage transistors the issue is still present on one channel.
Here is what I am seeing:
When the input signal hits a certain level 0.3 Vpp the whole circuit gets slammed. The DC voltages go crazy and the feedback loop causes the signal to clip. This only happens for a moment then the whole thing recovers.
The problem is inside the feedback loop as nothing strange happens to the signal when the side chain is either diconnected or the recovery switch is open. Or the THD is on. So it is safe to suggest that the amplifier is ok.
Normal reference DC Voltages taken from zero input signal to max input signal
VT15 (B = 0.8 to -1.33) (E= 0.545 to -0.165) (C= -20)
VT16 (B= 0.545) (E= 0) (C= 1.0 to 3.3)
VT17 (B= 1.0 to 3.3) (E= 0.5 to 2.8) (C= 18.26 to 17.97)
Broken
When the sidechain input hits 0.28 Vpp during that instant things get off
VT15 (B = -0.8) (E= -0.98) (C= -20)
VT16 (B= 0.430) (E= 0) (C= 4.0)
VT17 (B= 3.8) (E= 3.5) (C= 17.77)
If you continue past 0.28 Vpp the circuit does recover and acts as it should. DC voltages pretty much track the above reference.
I should also note that the circuit only does this peaky clip thing when coming from 0 up to 0.28 on the input of the side chain. Crossing 0.28 Vpp from a greater value does not cause it to ocurr again.
Another note is that the non-working side has a much higher swing in voltages on the collectors of VT2 and VT3. VT2 (C= -10.3 to -9.30) VT3 (C= -7.94 to -9.0)
The working side only has a 0.3VDC swing for each.
Chuck
ChuckD
Well-known member
Thanks
the problem is triggered as I said by the sidechain input signal hitting 0.28 Vpp
I am using an Input Pot by that is not relevant. as I said the Amplifier is working fine with out the Sidechain engaged.
Chuck
the problem is triggered as I said by the sidechain input signal hitting 0.28 Vpp
I am using an Input Pot by that is not relevant. as I said the Amplifier is working fine with out the Sidechain engaged.
Chuck
ChuckD
Well-known member
Thanks for the suggestions please keep them coming! Most of them I tried already But heating it I didn't think of that, It actually does make the Error different.
it may be a sort of Oscillation after all.
If I stick a heat gun on the area of the board on top of those 3 diodes going to the emitter of VT15 and heat all the surround parts just a bit it has an effect:
The Base voltage at VT16 is dropped to 4.5 and steady. The circuit no longer clips out but Oscillates a few times when the input signal is turned up to the same level.
As the heated circuit cools off the magnitude of the "few oscillations" gets larger and larger until it is a single large clip as before. As well the Base Voltage at VT16 is slowly raised back to 5.4 VDC (which is the steady base voltage on the working side)
What does heating up the diodes and surrounding parts do I wonder????
Chuck
it may be a sort of Oscillation after all.
If I stick a heat gun on the area of the board on top of those 3 diodes going to the emitter of VT15 and heat all the surround parts just a bit it has an effect:
The Base voltage at VT16 is dropped to 4.5 and steady. The circuit no longer clips out but Oscillates a few times when the input signal is turned up to the same level.
As the heated circuit cools off the magnitude of the "few oscillations" gets larger and larger until it is a single large clip as before. As well the Base Voltage at VT16 is slowly raised back to 5.4 VDC (which is the steady base voltage on the working side)
What does heating up the diodes and surrounding parts do I wonder????
Chuck
ChuckD
Well-known member
Works! R7 was shorting to the top ground plane!! Arrgh
Is it normal to have a big jump in volume between pin14 and 15 on the output gain switch??
Why is it like that? It doesn't seem natural but the resistors all check out to the schematic.
Chuck
Is it normal to have a big jump in volume between pin14 and 15 on the output gain switch??
Why is it like that? It doesn't seem natural but the resistors all check out to the schematic.
Chuck
desol
Well-known member
- Joined
- Jun 20, 2005
- Messages
- 2,184
Hey guys
I'm trying to understand a little more about the bypassing on this unit. ie: Thd/limit in relation to iron/bypass/clean.
For instance, if i have thd/limit switch set to thd, but iron/bypass/clean set to bypass...is everything bypassed...even thd?
I'm trying to understand a little more about the bypassing on this unit. ie: Thd/limit in relation to iron/bypass/clean.
For instance, if i have thd/limit switch set to thd, but iron/bypass/clean set to bypass...is everything bypassed...even thd?
Hank Dussen
Well-known member
I'm pretty sure the bypass is true bypass. In- and output directly connected (through relays) without anything else.
briomusic
Well-known member
thd/limit is basically a "sidechain-off" switch.
the signal will still be passed through the gain changing sections, but no compression will take place.
bypass is a hard bypass of the whole unit.
the signal will still be passed through the gain changing sections, but no compression will take place.
bypass is a hard bypass of the whole unit.
Michael Tibes
Well-known member
You can easily give it a try, with a perfectly transparent transformer the iron/clean switch just won't make any difference...baadc0de said:
Michael
haima
Well-known member
470m = 470uF
Hey guys,
I just did mine and now it's time to do some troubleshooting.. I thought to dump a few questions here and see if I get any answers I'll be off to work now and tackle this again in the afternoon..
For now I only "calibrated" +- 20V lines. All AOT resistors are as specified in the notes. I left the "unused" AOTs empty, should I replace them with wire links?
I did mine with R115 = link and with the optional 100k trimmer. I didn't check the schemo yet, but maybe I have to break connection at R115 for the trimmer to be in?
The problems I'm having right now are pretty basic I think.. the left channel's VU goes "down" and pegsa, instead of "up" to center at 0. The right one pretty much centers at zero (both are with hold set at middle, link disabled). If I turn the hold knob I can get the left one to deflect a little, while the right one seems to have a pretty much healthy swing imitating my hold setting. Both VUs and hold pots are wired the same (I checked) as are the wires connecting the small attack/release boards to the main boards.
After some time (say one minute) the right one's VU starts oscillating a bit, i.e. the needle goes up and down like a metronome. I think it's about 60bpm.
I put some sound through the left channel, but in iron mode I'm not getting anything and in clean mode I'm getting sound that isn't dependent on the input sound or volume (input can be muted / non present / disconnected but it will still do this). It's kind of like a complex square wave with some additional stuff soperimposed on it. It's definitely "synthesized" sounding. I may record a clip of it. It's very quiet though, about -50dB on my interface.
Thanks to all who read this and even more to any that are willing to help
I just did mine and now it's time to do some troubleshooting.. I thought to dump a few questions here and see if I get any answers
I'll be off to work now and tackle this again in the afternoon..For now I only "calibrated" +- 20V lines. All AOT resistors are as specified in the notes. I left the "unused" AOTs empty, should I replace them with wire links?
I did mine with R115 = link and with the optional 100k trimmer. I didn't check the schemo yet, but maybe I have to break connection at R115 for the trimmer to be in?
The problems I'm having right now are pretty basic I think.. the left channel's VU goes "down" and pegsa, instead of "up" to center at 0. The right one pretty much centers at zero (both are with hold set at middle, link disabled). If I turn the hold knob I can get the left one to deflect a little, while the right one seems to have a pretty much healthy swing imitating my hold setting. Both VUs and hold pots are wired the same (I checked) as are the wires connecting the small attack/release boards to the main boards.
After some time (say one minute) the right one's VU starts oscillating a bit, i.e. the needle goes up and down like a metronome. I think it's about 60bpm.
I put some sound through the left channel, but in iron mode I'm not getting anything and in clean mode I'm getting sound that isn't dependent on the input sound or volume (input can be muted / non present / disconnected but it will still do this). It's kind of like a complex square wave with some additional stuff soperimposed on it. It's definitely "synthesized" sounding. I may record a clip of it. It's very quiet though, about -50dB on my interface.
Thanks to all who read this and even more to any that are willing to help
