SCHEMATICS for v372D needed PLEASE

[[silent:arts]]

I was wondering if it's possible to add an output pot. Any ideas how to do that best?

Why? You might first let it pass audio and hear if you like it?

 

[sonolink]

From what I've heard about these amps I'm pretty sure I'll like it. Well I hope.so

I was thinking of being able to push the gain to hear more color.

 

[synthiaks]

This is a multi purpose amp so it could be used for stuff like line amplification or buffering. The +/- on the front is there to compensate for the differences in the gain when using more amps. The Resistors on the back wont be perfectly matched so the amps will not have the exact same gain.

The output pot would be an Attenuation potentiometer working as a resistor tied to ground i guess. You could the run the amp high and turn the output down. But you could do that in your DAW also.

Or do you want a Gain Potentiometer when you say "Output"?

And the maximum gain is 43dB and it can't be pushed anywhere higher than that.

 

[moamps]

I have uploaded the correct schematic for V372D.

http://groupdiy.com/index.php?topic=62842.0

 

[sonolink]

Synthiaks, thanks a lot for your input

This is a multi purpose amp so it could be used for stuff like line amplification or buffering. The +/- on the front is there to compensate for the differences in the gain when using more amps. The Resistors on the back wont be perfectly matched so the amps will not have the exact same gain.

Well that's more or less what I meant by "calibration" earlier in the thread. Sorry for my english
I'll keep in mind that it's then important to have that pot represented somewhere on the enclosure.

The output pot would be an Attenuation potentiometer working as a resistor tied to ground i guess. You could the run the amp high and turn the output down. But you could do that in your DAW also.

That's exactly what I meant. Regarding doing that in my DAW, I guess I could by i.e.: inserting a Trimmer plugin in the input of a channel in Pro Tools. But I'm in doubt here: don't you think that the signal should be attenuated to a healthy level before being converted? Just as an example, If I have a Kick or a very loud voice and I crank the gain up until it sounds VERY colorated and nice I will be saturating the preamp output. So far so good, but what if the signal also saturates the sound card input? It won't be levelled until it reaches Pro Tools right? Wouldn't it be better to level the signal just before entering the sound card? Or is it the same really?

Or do you want a Gain Potentiometer when you say "Output"?

No. I understand that I already have a Gain pot and to have another one to get more dBs I would need another stage. In any case I meant an output attenuator

And the maximum gain is 43dB and it can't be pushed anywhere higher than that.

Absolutely, and it probably is plenty anyway

I have uploaded the correct schematic for V372D.

Thanks Moamps!!

 

[synthiaks]

Synthiaks, thanks a lot for your input

No problems i love this sh*t!

Well that's more or less what I meant by "calibration" earlier in the thread. Sorry for my english
I'll keep in mind that it's then important to have that pot represented somewhere on the enclosure.

Its something you might have to calibrate once in a while but not really anything you need on the front.

That's exactly what I meant. Regarding doing that in my DAW, I guess I could by i.e.: inserting a Trimmer plugin in the input of a channel in Pro Tools. But I'm in doubt here: don't you think that the signal should be attenuated to a healthy level before being converted? Just as an example, If I have a Kick or a very loud voice and I crank the gain up until it sounds VERY colorated and nice I will be saturating the preamp output. So far so good, but what if the signal also saturates the sound card input? It won't be levelled until it reaches Pro Tools right? Wouldn't it be better to level the signal just before entering the sound card? Or is it the same really?

It all depends on what sound card you have and how the input is treated. With no proper pad or input attenuation it could be too hot no matter what you do, but then you should think about buying some real recording gear!

No. I understand that I already have a Gain pot and to have another one to get more dBs I would need another stage. In any case I meant an output attenuator

Just checking...

Absolutely, and it probably is plenty anyway

Not for a ribbon or any other low output microphone.

 

[synthiaks]

Put two 600ohm resistors in series with a dual 2k pot wired as a variable resistor and use it for the RGKs With the calibration potentiometers you then make sure the two channels are equal in gain for stereo use. or you use one Dual and one singel with a LINK switch for stereo use.

 

[sonolink]

It all depends on what sound card you have and how the input is treated. With no proper pad or input attenuation it could be too hot no matter what you do, but then you should think about buying some real recording gear!

This is my studio sound card: http://motu.com/products/avb/1248
I think it's proper enough 

I've been reading through the forum and found this similar idea although I find it curious that he wouldn't implement phantom on that rack...
http://groupdiy.com/index.php?topic=56654.0
Opinions on that Output pot? Should I implement it or it's fine using the sound card input attenuators?

 

[sonolink]

Put two 600ohm resistors in series with a dual 2k pot wired as a variable resistor and use it for the RGKs With the calibration potentiometers you then make sure the two channels are equal in gain for stereo use. or you use one Dual and one singel with a LINK switch for stereo use.

I was thinking of a stepped pot for that purpose but yours is a nice idea actually!
Is the 600R resistor because I won't find a 2K6 pot right?

 

[synthiaks]

the 600ohm would be the closest i could think of that would make the pot a value that could be obtainable you. The lowest resistance in the PDF is 300ohms but then the potentiometer need to be 2,6k.

Probably one could find a  parallel combination to, but im not that quick in math. The Dual/single with a switch is cool as you can hard link the channels and have them well calibrated if you want but flexibility with two mono signals too,

The schematic BTW is a School book example of a Discreet amplifier if someone want to learn transistor bias and functions this is the circuit to check.

S

 

[sonolink]

So no Output pot is useful right?

 

[[silent:arts]]

With 20% tollerance I wouldn't call a dual pot well calibrated ...
If you need stereo matching rotary switch are more accurate.

 

[moamps]

So no Output pot is useful right?

If you like to insert an output gain control, maybe the best solution is to insert the pot between stages. You can easily wire it because you have a lot of free pins on multipin connectors.

 

[[silent:arts]]

But now you don't have the saturation padded down, only the signal  ;D

 

[moamps]

It looks to me that the saturation should happen in the first stage, but you are maybe right.  ???

 

[[silent:arts]]

I doubt there is any useful saturation. This is a german broadcast module, designed to be clean (until it distorts).
If "the sound" is hotter than the next stage can handle the only way is to pad the output, after the module.

However, before thinking about all this (possible) options I first would make sure the units are working, and hear how they sound 

 

[DerEber]

However, before thinking about all this (possible) options I first would make sure the units are working, and hear how they sound 

Yea fire it up! Use it. At least check if you really dig it when driving too hot.
Maybe you won't want the Output Pad.

 

[sonolink]

Ok guys I was just pondering the output pot to get all in one order but Volker is right, I should listen to it first. So I'm going to take care of the caps and the RGK pot first and see what happens. If all is good I'll go to the next step and consider stepped gain and an output pot.

So it's a 2k log pot with a 600 ohms 1/4W resistor I need right?

 

[synthiaks]

With 20% tollerance I wouldn't call a dual pot well calibrated ...
If you need stereo matching rotary switch are more accurate.

The idea was to use the +/-1,5dB for L/R calibration for the dual pot and not put them on the front panel. 3dB spread all in all should cover the potentiometer resistance difference when switched in link mode.

I also agree on the saturation issue. This is clean amps the distortion from them will probably not sound that nice. Think late studer 900 series. Some East German kölleda germanium amps are what you need!

S

 

[sonolink]

Does anyone know what are those circled numbers on the schematic?