All things G1176 - the new "repost" thread.
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dustbro
Well-known member
[quote author="gswan"]It's not the way I would do it. The ground from the AC connector is a protective earth. It should go straight to the metal chassis. It should only be connected to the PSU 0V/GND at a single point at the power supply.
[/quote]
This worked like a charm. I am now hum free...
And the output mod to 1:2 was super simple once I realized that all I had to do was turn the transformer around. Just drilled a hole in the PCB where the ground pin needed to go, and then soldered a wire from the pin to the old ground pad.
I definetely felt like giving up a few times.. but after cutting the ground traces, moding the output to 1:2, swapping out the 10K resistor for a 3.7k to adjust threshold, and proper grounding scheme, these compressors are ready for action!
[/quote]
This worked like a charm. I am now hum free...
And the output mod to 1:2 was super simple once I realized that all I had to do was turn the transformer around. Just drilled a hole in the PCB where the ground pin needed to go, and then soldered a wire from the pin to the old ground pad.
I definetely felt like giving up a few times.. but after cutting the ground traces, moding the output to 1:2, swapping out the 10K resistor for a 3.7k to adjust threshold, and proper grounding scheme, these compressors are ready for action!
ChrioN
Well-known member
Another Q: As I understand it, attack and release time is increased by rotating the pots CCW. If you want to make it reveresed, increasing time by turning CW, can one simple switch out the outer legs of the pots?
gswan
Well-known member
Yes, however remember to also change the position of the pots in your calibration procedure. Also, if they are log pots then the attack and release times won't be mirrored in the other direction.
bluesman714
Well-known member
- Joined
- Mar 31, 2005
- Messages
- 74
I am about to pull the trigger on a Type: Y236106 (25+25V @ 30VA) Toroidal transformer from Avel Lindberg Inc.
Could one of you kind souls who are in the know please verify that this will work to power a dual 1176 using Mnats version J boards.
Many Thanks In Advance
Could one of you kind souls who are in the know please verify that this will work to power a dual 1176 using Mnats version J boards.
Many Thanks In Advance
bluesman714
Well-known member
- Joined
- Mar 31, 2005
- Messages
- 74
I found the answer by modifying my search.....& am going with the Y236106 (25+25V @ 30VA) Toroidal transformer from Avel Lindberg, mentioned several times throughout the 1176 meta.
thanks!
thanks!
Siegfried Meier
Well-known member
Hey guys,
Still working away at calibrating a pair of the Rev J Mnats 1176's. I finally matched some FETs and decided to start over and redo the entire calibration process as it always seemed to compress too much.
So now I feel pretty comfortable with how the units are operating, but my main concern is that I cannot get enough output level to Pro Tools, no matter what I do. If I crank the input too much, then I get too much compression, and the output volume won't give me enough level. I'm using Lundahl ins and outs, the in is wired normal 1:1 and the output is wired 1:2. Is this the problem?
Thanks,
Siegfried
Still working away at calibrating a pair of the Rev J Mnats 1176's. I finally matched some FETs and decided to start over and redo the entire calibration process as it always seemed to compress too much.
So now I feel pretty comfortable with how the units are operating, but my main concern is that I cannot get enough output level to Pro Tools, no matter what I do. If I crank the input too much, then I get too much compression, and the output volume won't give me enough level. I'm using Lundahl ins and outs, the in is wired normal 1:1 and the output is wired 1:2. Is this the problem?
Thanks,
Siegfried
Maybe the previously mentioned threshold mod can help you?
Jakob E.
Jakob E.
Siegfried Meier
Well-known member
Is this also the case when using both Lundahl ins and outs?? I should mention that there's plenty of gain when in bypass mode, just no when compressing making them both useless. Sigh. I'm pretty down about building these units. After spending so much time and money, I'm quite regretting it.
gswan
Well-known member
[quote author="Siegfried Meier"]I should mention that there's plenty of gain when in bypass mode, just no when compressing making them both useless.[/quote]
That's kind of important information. Have you wired a true bypass or are you simply referring to the 'gain reduction off' as bypass (which it is not)?
In the latter case, it sounds as if your FETs are conducting all the time, and hence attenuating the signal all the time. This is a sign of mis-calibration (or circuit construction error). You should only have 1dB of signal attenuation with no compression, that's the key to the calibration procedure.
[quote author="Siegfried Meier"]Sigh. I'm pretty down about building these units. After spending so much time and money, I'm quite regretting it.[/quote]
I've noticed quite a few people attempting to build tricky analogue equipment with little or no electronics experience or knowledge, which can bite you if you run into problems. :?
Classic analogue equipment is expensive because it uses carefully selected and sometimes handmade components which often need to be hand matched and then calibrated and tested by hand. This is very labour-intensive.
That's kind of important information. Have you wired a true bypass or are you simply referring to the 'gain reduction off' as bypass (which it is not)?
In the latter case, it sounds as if your FETs are conducting all the time, and hence attenuating the signal all the time. This is a sign of mis-calibration (or circuit construction error). You should only have 1dB of signal attenuation with no compression, that's the key to the calibration procedure.
[quote author="Siegfried Meier"]Sigh. I'm pretty down about building these units. After spending so much time and money, I'm quite regretting it.[/quote]
I've noticed quite a few people attempting to build tricky analogue equipment with little or no electronics experience or knowledge, which can bite you if you run into problems. :?
Classic analogue equipment is expensive because it uses carefully selected and sometimes handmade components which often need to be hand matched and then calibrated and tested by hand. This is very labour-intensive.
dustbro
Well-known member
[quote author="Siegfried Meier"]After spending so much time and money, I'm quite regretting it.[/quote]
I knew that feeling... I wanted to rip my hair out after building these things. BUT during the process I have learned so much that has gotten me thru a few other problems on various projects that I would have never figured out. Just look at this thread! It took me 10 pages of questions and more than a month of tinkering to get these complete. If the threshold is your only problem, then you're doing pretty good!
I knew that feeling... I wanted to rip my hair out after building these things. BUT during the process I have learned so much that has gotten me thru a few other problems on various projects that I would have never figured out. Just look at this thread! It took me 10 pages of questions and more than a month of tinkering to get these complete. If the threshold is your only problem, then you're doing pretty good!
Siegfried Meier
Well-known member
Well, I wouldn't exactly say I have little or no experience. I've built a slew of things like the GSSL, LA2A, SCA N72's, 312's, GPultecs, racked tons of gear for many years, so I do kinda know what's going on. The biggest problem is several different sources for the calibration procedure and each one contradicts the next. I clearly have something wrong with my calib process, so I'm going to need to find a document that I can truly follow that is made for the Mnats/Gyraf board. I think I'll change the input lundahl to 2:1 as well, and see if that helps with the level issues I'm having.
Thanks,
Siegfried
Thanks,
Siegfried
[quote author="gswan"][quote author="Siegfried Meier"]I should mention that there's plenty of gain when in bypass mode, just no when compressing making them both useless.[/quote]
That's kind of important information. Have you wired a true bypass or are you simply referring to the 'gain reduction off' as bypass (which it is not)?
In the latter case, it sounds as if your FETs are conducting all the time, and hence attenuating the signal all the time. This is a sign of mis-calibration (or circuit construction error). You should only have 1dB of signal attenuation with no compression, that's the key to the calibration procedure.
[/quote]
As I said, the threshold mod is probably what you need.. :thumb:
Jakob E.
That's kind of important information. Have you wired a true bypass or are you simply referring to the 'gain reduction off' as bypass (which it is not)?
In the latter case, it sounds as if your FETs are conducting all the time, and hence attenuating the signal all the time. This is a sign of mis-calibration (or circuit construction error). You should only have 1dB of signal attenuation with no compression, that's the key to the calibration procedure.
[/quote]
As I said, the threshold mod is probably what you need.. :thumb:
Jakob E.
matta
Well-known member
Hi Guys,
I'm really struggling with coming to grips on the Calibration of my G1176 unit, according to the instructions below.
The first part is easy. I send a SIN wave at 1Khz out of my Pro Tools system and adjust the output until i read 50mV AC between pins 2+3 on my multimeter (anyone know if this should be PEAK 2 PEAK or RMS? I'm guessing PEAK 2 PEAK) on the INPUT XLR of the G1176, all this while the METER s set to BYPASS, I then set the INPUT LEVEL POT to 12 o'clock, and the OUTPUT LEVEL POT to match the 50mV input, which is my case is around 10 o''clock (using an IC balanced input). Up to there I am A ok... but now...
The next part of the instruction is to switch the METERING to GR and adjust the INPUT SIGNAL LEVEL (Signal Generator) till the OUTPUT measures HALF the INPUT level... well this is where things go awry...
The moment I switch to GR from BYPASS and increase the the INPUT SIGNAL LEVEL the OUTPUT remains unchanged at the 50mV I set it to, the only way to CHANGE the OUTPUT LEVEL would be to increase the OUTPUT by using the POT... which in a way makes rational sense, but not what the instructions above imply.
I can DECREASE the Signal Generator level so that it matches HALF the output, but this seems backwards...
Any help would be MUCH appreciated. The unit is working fine and sounds great but the METER calibration is WAY off and I want to get this in spec as best I can.
Cheers
Matt
I'm really struggling with coming to grips on the Calibration of my G1176 unit, according to the instructions below.
The first part is easy. I send a SIN wave at 1Khz out of my Pro Tools system and adjust the output until i read 50mV AC between pins 2+3 on my multimeter (anyone know if this should be PEAK 2 PEAK or RMS? I'm guessing PEAK 2 PEAK) on the INPUT XLR of the G1176, all this while the METER s set to BYPASS, I then set the INPUT LEVEL POT to 12 o'clock, and the OUTPUT LEVEL POT to match the 50mV input, which is my case is around 10 o''clock (using an IC balanced input). Up to there I am A ok... but now...
The next part of the instruction is to switch the METERING to GR and adjust the INPUT SIGNAL LEVEL (Signal Generator) till the OUTPUT measures HALF the INPUT level... well this is where things go awry...
The moment I switch to GR from BYPASS and increase the the INPUT SIGNAL LEVEL the OUTPUT remains unchanged at the 50mV I set it to, the only way to CHANGE the OUTPUT LEVEL would be to increase the OUTPUT by using the POT... which in a way makes rational sense, but not what the instructions above imply.
I can DECREASE the Signal Generator level so that it matches HALF the output, but this seems backwards...
Any help would be MUCH appreciated. The unit is working fine and sounds great but the METER calibration is WAY off and I want to get this in spec as best I can.
Cheers
Matt
matta
Well-known member
Yeah... bumping this... :green:
gswan
Well-known member
Try to understand what you are doing and it might make sense. It's also measures as RMS voltage, not p-p.
You are starting with the unit not compressing (50mV).
You are supposed to increase the level of the signal generator until the output halves.
You are trying to move over the threshold where compression starts.
If you plot input to output you will start to see a point where the output no longer tracks the input directly. This is known as compression.
You are trying to show the amount of gain reduction on the meter. Once you measure a known gain reduction, you calibrate your meter to show this.
Simple enough?
You are starting with the unit not compressing (50mV).
You are supposed to increase the level of the signal generator until the output halves.
You are trying to move over the threshold where compression starts.
If you plot input to output you will start to see a point where the output no longer tracks the input directly. This is known as compression.
You are trying to show the amount of gain reduction on the meter. Once you measure a known gain reduction, you calibrate your meter to show this.
Simple enough?
Hello,
first thanks to all for this helpfully forum.
I have built the 1176LN rev#F from Gyraf without the input
transformer and I don't know if it works right.
I think the gain of my device is to weak. I tried to calibrate my
device. So first I use a 1kHz signal with 0,775V at the Input and I
only get max 0,585V at the Output (Input Vol = full, Output Vol =
full). Is that right? Did it only have a negative gain?
I have checked several times the voltages and the parts, looks all good.
There is a manual here to change the gain, but before I changed
anything I want to know if my device works right.
Maybe someone can help me !?!?
first thanks to all for this helpfully forum.
I have built the 1176LN rev#F from Gyraf without the input
transformer and I don't know if it works right.
I think the gain of my device is to weak. I tried to calibrate my
device. So first I use a 1kHz signal with 0,775V at the Input and I
only get max 0,585V at the Output (Input Vol = full, Output Vol =
full). Is that right? Did it only have a negative gain?
I have checked several times the voltages and the parts, looks all good.
There is a manual here to change the gain, but before I changed
anything I want to know if my device works right.
Maybe someone can help me !?!?
Hi Ryan,
Welcome to GroupDIY!
Maybe the above-mentioned threshold mod? If you have plenty of gain without the attenuator FET in place, your problem may be too low a threshold (or try a different FET - make sure to use the right version!)
Jakob E.
Welcome to GroupDIY!
Maybe the above-mentioned threshold mod? If you have plenty of gain without the attenuator FET in place, your problem may be too low a threshold (or try a different FET - make sure to use the right version!)
Jakob E.
Hi Jakob,
thanks for your fast reply.
Based on your statement the gain of my device is to weak. What is the right gain of it?
Ok I have replaced the FET and it's the same (IN=0,778 OUT=0,591). What's the problem?
I have testet different FET's all the same. I use a BF245A, that's right or not?
RyanB
thanks for your fast reply.
Based on your statement the gain of my device is to weak. What is the right gain of it?
Ok I have replaced the FET and it's the same (IN=0,778 OUT=0,591). What's the problem?
I have testet different FET's all the same. I use a BF245A, that's right or not?
RyanB
gswan
Well-known member
Check the signal as it goes through the unit. Try measuring at the output of the input amplifier (at the top of the input level control with the wiper turned all the way down). Is the signal attenuated?
Then check it on the FET Drain, with the wiper of the input turned all the way up. Check Vgs of the FET with no signal and see where it sits in relation to the FET conduction curve. Is it biassed on? Can you back off the Q Bias adjustment to restor full signal there? Is the Vgs voltage not varying enough to allow the FET to be turned off?
Then check it on the FET Drain, with the wiper of the input turned all the way up. Check Vgs of the FET with no signal and see where it sits in relation to the FET conduction curve. Is it biassed on? Can you back off the Q Bias adjustment to restor full signal there? Is the Vgs voltage not varying enough to allow the FET to be turned off?
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