[BUILD] 1176 Rev A - Back to the beginning...

[haystack]

Thanks for replying.

I have had the unit on only for a couple  or so hours at a time.
I have run some mono bass tracks through it,  but other than that not really put it through it's paces. It sounded great.  It seems to  responds as it should.
The videos were by you dbonon and the input/output knobs corresponded as yours did in the calibration- high inout low output.

I just noticed the drift but perhaps I need to let it settle in for longer. I am not sure if it goes up and down all the time though.

Thank you

Haystack

 

[dbonin]

Thanks for replying.

I have had the unit on only for a couple  or so hours at a time.
I have run some mono bass tracks through it,  but other than that not really put it through it's paces. It sounded great.  It seems to  responds as it should.
The videos were by you dbonon and the input/output knobs corresponded as yours did in the calibration- high inout low output.

I just noticed the drift but perhaps I need to let it settle in for longer. I am not sure if it goes up and down all the time though.

Thank you

Haystack

ok, after warm up (say 30 minutes) you should be able to zero the meter in GR and and then experience very little drift.
I thought you meant that it would drift down then drift back up all on it's own. 

 

[haystack]

I am going to look at it in a moment again.

Yes, it did drift on it's own accord. Last night  it was at zero initially for a while. but started to move into the hot area and stay there until I turned it off.
Did Mike suggest there may be some drift in the circuit naturally.

cheers guys.

Hay

 

[dbonin]

I am going to look at it in a moment again.

Yes, it did drift on it's own accord. Last night  it was at zero initially for a while. but started to move into the hot area and stay there until I turned it off.
Did Mike suggest there may be some drift in the circuit naturally.

cheers guys.

Hay

Yes, -INITIAL- drift is normal  but after it warms up and the meter is zero'd in GR mode, there should be little drift EVER after that.  I don't have to zero the meter every time I use my units. My units all sit at zero after warm up and don't move - they have been like that for years now.

 

[haystack]

Hi dbonin

Thanks for replying.
I will keep an eye on it this evening.
I would like to take the opportunity to say how delighted I am with the kit. It has top class components and I was especially impressed with the chassis. Wonderful kit.

Thanks again
Hay

 

[mnats]

The subject of GR meter drift, amongst other common issues, is covered in the FAQ linked from the first post of this thread.

I am going to look at it in a moment again.

Yes, it did drift on it's own accord. Last night  it was at zero initially for a while. but started to move into the hot area and stay there until I turned it off.
Did Mike suggest there may be some drift in the circuit naturally.

cheers guys.

Hay

 

[haystack]

Got it mnats -thanks  DIdn't think of looking there.  That must be it.
cheers
Hay

 

[rdp42089]

To follow up on the previous post regard the Hairball Rev A compressor.  I just built the Rev D power supply from the full kit which should be identical to the Rev A power supply from the full kit to do a diagnostics test.  I checked the values of all the resistors and it seems that everything is in order on both the main PCB and the Meter PCB.

However I am still getting 24vDC instead of 30V from R87  and -10V from CR6 with the completely new kit with .  The voltage regulator seems to be on straight (I tested with and without the heat sync) .

Is it possible that I have the wiring wrong? 

On the bottom of the meter switch, I have L from the mains transformer going to the top middle lead and N going to the bottom middle lead.  If this was wired incorrectly would it have an effect on the voltage?

Thanks,
Danny

Also in the Hairball

 

[Echo North]

To follow up on the previous post regard the Hairball Rev A compressor.  I just built the Rev D power supply from the full kit which should be identical to the Rev A power supply from the full kit to do a diagnostics test.  I checked the values of all the resistors and it seems that everything is in order on both the main PCB and the Meter PCB.

However I am still getting 24vDC instead of 30V from R87  and -10V from CR6 with the completely new kit with .  The voltage regulator seems to be on straight (I tested with and without the heat sync) .

Is it possible that I have the wiring wrong? 

On the bottom of the meter switch, I have L from the mains transformer going to the top middle lead and N going to the bottom middle lead.  If this was wired incorrectly would it have an effect on the voltage?

Thanks,
Danny

Also in the Hairball

Did you say you tested the power supply before you stuffed the rest of the PCB and it was fine?

 

[rdp42089]

Yes,

I believe that I figured out the problem.  According to the MNATS wiring guide for the transformer (http://mnats.net/1176_reva-d_hairball_wiring_power_avel-lindberg.html) I had the wiring backwards coming out of the primary windings.

I then flipped the wires on both chasis and now all seems to be well with the power supplies ~30V on R87 and ~-10V on CR6.  Still need to test whether or not the gain reduction circuit will work on the Rev A.  The Rev D is almost complete.  Fingers crossed.

Thanks,
Danny

 

[MicDaddy]

little snippet I ran across spec'ing a transformer for another project...

http://www.hammondmfg.com/1182.htm

"Note about Inrush Current:
Due to the superior magnetic properties of Toroidal transformers they will be susceptible to high magnetizing current when initially energized, only limited by the low DC resistance of the primary winding. Depending on where you are in the AC cycle when the transformer is energized dictates the chances of overloading the supply circuit. This is why the transformer may sometimes energize without a problem and other times it will blow the fuse or trip the circuit breaker. The duration of this overload is rarely longer than a half of a cycle. Therefore, you should consider using a slow-blow fuse, time delayed circuit breaker or other form of soft start circuitry for the supply line when using these high efficient Toroidal transformers."

 

[eqp1a]

I'm building a pair of Rev As (ver 1.2.5), and they're both exhibiting the exact same problem. They're both approximately 10db louder than my Rev A (ver 1.2) with compression bypassed, and with compression instantiated the effect is almost more distortion than compression, though there certainly is still compression happening. Though the attack pot is definitely functioning, it can be hard for me to tell as the distortion is making it hard to hear. The release pot is also functioning as it should, but also seems to act like a distortion control. With the slowest release, there's no noticeable distortion, and as you increase the speed it's as if you're dialing in distortion at the same time. Also, I'm getting slightly off DC voltages at Q2. Q2 Gate: 1.34V (2.22V per mnats); Q2 Drain: 6.09V (6.73V per mnats); Q2 Source: 4.27V (4.51V per mnats).

I've built plenty of these before and never had any issues. I've double and triple checked the wiring, resistor values, capacitor values and orientation, etc., and everything seems to be as it should. I'm a bit stumped. Any help would be greatly appreciated.

Cheers

Ian

 

[dbonin]

Just to be sure,  make sure your output and release pot are not swapped.

I'm building a pair of Rev As (ver 1.2.5), and they're both exhibiting the exact same problem. They're both approximately 10db louder than my Rev A (ver 1.2) with compression bypassed,

 

[eqp1a]

Nope, definitely not swapped.

Just to be sure,  make sure your output and release pot are not swapped.

I'm building a pair of Rev As (ver 1.2.5), and they're both exhibiting the exact same problem. They're both approximately 10db louder than my Rev A (ver 1.2) with compression bypassed,

 

[Bonsaimaster]

Just got done with the rev A. First calibration step went great. Second step not so good. I am using the Test points as required for rev a. I cannot zero out the voltage. Any thoughts?

Thanks in advance.

 

[Echo North]

Just got done with the rev A. First calibration step went great. Second step not so good. I am using the Test points as required for rev a. I cannot zero out the voltage. Any thoughts?

Thanks in advance.

• Jumper in the right place?
• Using DC on your meter?
• Trimmer installed correctly?
• No signal?
• Does the reading change at all when you rotate?

 

[dbonin]

Is the orientation of your input transformer correctly in the step-down position?

I'm trying to think what might cause the increase of 10 db...

Are you getting 10 db of compression measured on the output when you turn GR on @ 20:1 ratio?

Nope, definitely not swapped.

Just to be sure,  make sure your output and release pot are not swapped.

I'm building a pair of Rev As (ver 1.2.5), and they're both exhibiting the exact same problem. They're both approximately 10db louder than my Rev A (ver 1.2) with compression bypassed,

 

[TubeMonkey]

Hi all,

Thanks in advance to all the guys on here answering all these questions.  I'm stumped on my 1176 build, here are my current voltages on the line amp section... everything up until here tests fine. any ideas on what could be causing the drop to 13v on the other side of  r35?  i've replaced all three transistors in this section on advice from an earlier post, but that doesn't seem to be the problem . Any and all help is appreciated.  Thanks!

 

[TubeMonkey]

So it turns out dyslexic me put in a 1.5k resistor (brown/green/red) instead of a 1.2M (brown/red/green) into the spot for R29, causing the whole line amp to blow up, and frying R32.  Another issue i've corrected which may help other's having the same symptom is this: initially the unit didn't seem to be compressing, however, if none of the ration push buttons were enganged, the unit WOULD compress. I tracked this down to Pad 22 being swapped with the Ground pad next to it. The unit is calibrated and working great now and sounds killer.

 

[wnlively]

Hi
I've finished my first rev a build
I was concerned that I recived 2 Wima film caps in stead of the 2 smaller Orange drops.
I've got it up and running and all is well and calibrated correctly.
My only concern is that it doesn't seem to to take much signal to make the unit distort.
the unit acts right and compresses . The vu meter doesn't move much before I get distortion.
Is this the charter of the rev a?
It sound fine ,just can't crank on it much.
Thanks for any help.
Wnlively