[BUILD] 1176LN Rev D DIY

[Neko Neko]

 

[Echo North]

I know the output transistor runs hot, but how hot is too hot? I have a top hat heat sink on it but it's still very hot. About a second is how long I can grab it.

That leads me to my next question. I have the mnats power supply with the 317/337's. Is this enough to power two REV D's?
I'll probably need to heat sink these to the chassis or something.

Which leads me to my next question. Does this look like the right substance? http://www.ebay.com/itm/20g-Tube-Syringe-Silver-Thermal-Paste-High-Performance-Heatsink-Compound-CPU-GPU-/131753508718?hash=item1ead1eff6e:g:rtIAAOSwCQZZIgqt

Also, I'm not hitting on something at mouser at the moment that has these little miscellaneous parts like the little rubber thing that isolates the screw from the to220 chip. Or the little pad that goes on the back. Does someone have a link to the little miscellanious stuff?

By the way, the Ed Anderson transformer  (with class A out) is really amazing sounding. I got a chance over a few years actually to go from these G1176 boards with a chip input and an OEP out to eventually a 600 ohm T pad/Altran input transformer with a cinemag  CMOQ output (REV F pretty much, less output gain at 1:2), to eventually just deciding to breadboard the class A output and go full REV D. So, now it's gonna be a stereo REV D. Just sounded right to me.  Still would like to hear the REV F with the Ed Anderson for the A/B output.

- It get hot. Very hot, too hot to touch. Put a bigger heat sink on it if you like.
- 317/337 are not the issue, it's the VA rating of the power transformer.
- They are running at low current (<500mA).  A basic TO-220 heatsink is fine.

 

[Echo North]

And the guts  8)

Very cool!

 

[JW]

Okay,

I think maybe I spoke too soon on the heat issue. I left it on for a few hours and the output transistors are about as hot to the touch as a preamp tube or something. So, not really that bad and they don't seem to be getting much hotter with time.

Here's a couple pics of my dual unit. I'll probably just put some normal heat sinks on the regulators.

 

[JW]

inside

 

[JW]

guts 2

Notice the little breadboarded class A outputs. Really digging these compressors. Will have to calibrate again I think, but they calibrated fine when they were rev G's. . . . .

 

[Echo North]

Okay,

I think maybe I spoke too soon on the heat issue. I left it on for a few hours and the output transistors are about as hot to the touch as a preamp tube or something. So, not really that bad and they don't seem to be getting much hotter with time.

Here's a couple pics of my dual unit. I'll probably just put some normal heat sinks on the regulators.

The output transistor gets very hot yes.

Mike

 

[Spencerleehorton]

I have just put together a 1176 rotary switch version and i'm stuck!!!
at point 28 im supposed to get 10v but only getting 1v? strange thing is when i turn on the unit i can see 9.5v there for a millisecond then it goes down to 1v?
also when i turn the unit off, for a split second after i can see signal gets bigger and Meter comes to life?

any ideas?

 

[Spencerleehorton]

i have tracked a few more things down:

getting 12v on release pot, which seems to be coming from pin 19

removed Q1 and signal comes through good

if remove pin 18 and pin 19 GR functions on meter

ive taken the ratio pcb off and im going to test

 

[Spencerleehorton]

I have already hunted through these posts and found something similar on 230 but doesn’t fix my problem.
My problem area is 12v on pad 19.
If I disconnect pad 19 the meter works a bit but no GR?

Any ideas anyone?

 

[Spencerleehorton]

is there no longer any support for this?

 

[Echo North]

is there no longer any support for this?

I'm happy to help generally, but I've just lost track of where you are.

IIRC correctly you wound your own transformers, changed values, and hacked up your board a little.  I think it's totally cool that you've decided to experiment with the circuit and try out stuff, but from a support perspective it just limits what I can do because I can't assume anything about your setup.

You don't mention if your Pad 19 voltage is AC or DC.  There should be no AC at pad 19.  There will be a DC value based off the track of the DC ratio ladder but it should never be a negative DC value.

So yes, something is off in your circuit. Seems like either CR2 or CR3 C19 or C20 are damaged allowing the positive DC voltage from the side chain to leak into the release pot.

Good luck,

Mike

 

[Spencerleehorton]

I’ve managed to sort it now, changed both the 6.8uf tants as they must have been damaged now have working unit.
Waiting on some 200pf mica caps to change as I’ve used 2 100pf in parallel but this is just so it looks a bit neater.
Can’t get -10db drop yet but I’m sure I can tweak a bit more and find out what’s wrong.
Now I have Rev A and Rev D from you and 3 x g1176, will probably mod the g1176 to Rev D now as I’ve come up with a mod to try and g1176 to my mind has much lower output.

 

[Echo North]

I’ve managed to sort it now, changed both the 6.8uf tants as they must have been damaged now have working unit.
Waiting on some 200pf mica caps to change as I’ve used 2 100pf in parallel but this is just so it looks a bit neater.
Can’t get -10db drop yet but I’m sure I can tweak a bit more and find out what’s wrong.
Now I have Rev A and Rev D from you and 3 x g1176, will probably mod the g1176 to Rev D now as I’ve come up with a mod to try and g1176 to my mind has much lower output.

Ah right I misspoke. Obviously C19/C20 block the DC before it reaches the CR2/CR3 rectifiers.

Low compression is usually:

1) Low AC voltage at pad 22
2) Low gain in the side chain amp
3) Improper neg DC threshold voltage (pad 21)

We'll be posting those voltages shortly on our site.

Mike

 

[Spencerleehorton]

Great stuff, would be good to have them voltages for future, I’ve dived into recording with it as I’m so impatient!!!!
Will setup properly once this albums finished!!!

 

[Spencerleehorton]

Right well thank you to the wonderful Mike from hairball for putting up a very comprehensive guide on their site.
I had a few minutes to look at what’s going on with mine and I’m a bit boggled to what’s going on!
On R74 one side I have 2.9v on the other it’s 5v?
Both the GR and VU sit at -10db and the unit seems to function well.
The strange thing is I know it’s not setup right as either side of R74 it’s meant to be at least 10v.
Whatever I do I can’t get 10v here and the meter to sit correctly.
Which must mean my meter is not quite right?
Can we use other meters on this?

 

[scott2000]

The strange thing is I know it’s not setup right as either side of R74 it’s meant to be at least 10v.
Whatever I do I can’t get 10v here and the meter to sit correctly.

So this 10v is supposed to be typical voltage with a fully calibrated unit. With no input, GR mode and 1/2 hour of warm up?

When you say whatever I do, are you referring to trying to calibrate? 

 

[Spencerleehorton]

Yes, it’s weird because I can setup the unit to get -10db with compression on both Vu and GR mode but this involves adjusting the q-bias in a way where it is not +1 dB drop.
If I follow normal setup procedure qbias is good, then setting R74 to 0v is good but I’m left with a Vu meter which is way off?
Can only get about -3db drop on GR but get -10db drop on Vu mode?

 

[scott2000]

Yes, it’s weird because I can setup the unit to get -10db with compression on both Vu and GR mode but this involves adjusting the q-bias in a way where it is not +1 dB drop.
If I follow normal setup procedure qbias is good, then setting R74 to 0v is good but I’m left with a Vu meter which is way off?
Can only get about -3db drop on GR but get -10db drop on Vu mode?

I know Phrazemaster (Mike) says something has to be wrong with something if you can't get the  calibration right. He has an A that had some issues with some traces and I believe he replaced the transistors but ended up getting it to work, Has some new issues though.... It's on the relevant thread....

Geez these calibrations issues are crazy..... Got me scared to even try a build ..... but I hear they are sweet.....

 

[Spencerleehorton]

yeah funny thing is my Rev A suffers from the exact same problems!!!
Once i find out what it is, i reckon it'll be one fix for them both!!!

Another strange thing is my output control on both Rev A and Rev D i only have to have up a little and both units are blasting it out?
my Rev A has a OEP 1:2 input txf and the EA-5002 and uses all the other correct parts apart from the VU meter.
My Rev D uses an 1:2 self wound input txf and an output txf self wound with 2n5088 transistors in replacement of the 2n3707 and uses the 2n5457 this also uses a VU meter out of a A&H mixer Vu section.
I will test the Vu meters again with 0.775v signal and 3.9K resistor to see if i get 0db, pretty sure i did this before but its been such a long time of trying to find out whats wrong i kinda need to start again!!!