[BUILD] 1176LN Rev D DIY

[Echo North]

I went to great lengths to build a matched pair of 1176s. I did the matching myself and went through a lot of FETs in order have a matched quad.
Even with the nice stereo link boards, the FETs all need to be matched I think

They need them to be reasonably matched with the linking PCB.  Say within 10%.

If you're using the direct link (pad 7) method, you'll want them as close as you can get (1% or better).  The problem with that method is that the curve can change in each device slightly with heat.

 

[andydiy]

Hi!

I am a DIY Primary .

I have direct at Hairball Audio & MNATS purchased 1176LN Revision D Boards PCB.

Someone can you been introduced into good Hook, up Wire?

For example: PCB to the Power wire / PCB the To the XLR wire and so on.

thickness how much it?

Mogami & Belden can it?

Thank you!

 

[Echo North]

Hi!

I am a DIY Primary .

I have direct at Hairball Audio & MNATS purchased 1176LN Revision D Boards PCB.

Someone can you been introduced into good Hook, up Wire?

For example: PCB to the Power wire / PCB the To the XLR wire and so on.

thickness how much it?

Mogami & Belden can it?

Thank you!

Generally 22 gauge is used for hookup.  Belden makes nice wire, but so do others.  I'd go with something heavier  for the chasis ground, maybe 16 gauge.

For the shielded I like the Canare L-2B2AT or something small like that.  Regular microphone cable is too bulky in the enclosure.

 

[usekgb]

I went with a Beldin something-or-other that I had surplus from doing a bunch of patch bays.  22ga, with foil shield and ground wire.  It was really easy to work with, but it was a bit on the large side.  I really liked having the foil shield because it has 100% shielding coverage throughout.

Cheers,
Zach

 

[number2]

Seems you are down to a problem with the metering circuit.

R74 should be seeing 0V on one leg, and -10v through the resistors off the other leg. I don't see how it could be positive.
Take a few minutes to try to understand the schematic. Learn ohm's law and see how the voltages are interrelated.

DMP can you explain more or give one example of what you are saying about ohm's law here?

I have this: E=IR
for R74: E= -10v, R = 2.7 Mohms, I=-10/2.7 x10^6

are you saying that the problem is in the GR meter driver section of the PCB then?

 

[dmp]

DMP can you explain more or give one example of what you are saying about ohm's law here?

Sure. First of all, the schematic I've been looking at has R74 = 1k. So we must be looking at different schematics, which is a problem.
I am looking at the "Revision 1.2.5 with typical voltages" that mnats has posted on his rev A page.
Ohm's Law is V=IR. If you have three resistors in series and one side has -10v and the other has 0v, then you can use ohm's law to see what the voltage should be between the resistor intersections.
Since the current is equal in each resistor, the voltage drop across each resistor (dV) is related dV/R=dV/R=dV/R for all three resistors. And the total voltage drop dV+dV+dV=-10.
This simple math tells you that the voltages are all going to be negative.

From the evidence you've posted, it sounds like the GR meter circuit is not correct. You should be able to zero the meter, and there should be positive voltage on the collector of Q13.
The GR amp might have a problem as well, since you said the unit is not compressing signal.

 

[HMPS]

Hey folks,

Where should I test the power rails for 30vdc and -10vdc?

Also should the pcb be grounded before proceeding?

Thanks!

 

[Echo North]

Hey folks,

Where should I test the power rails for 30vdc and -10vdc?

Also should the pcb be grounded before proceeding?

Thanks!

Your center tap is you common.

Look at the PCB around R87 and you'll see an arrow pointing to one of the pads that reads "<+30V".  Measure between that point and the center tap.  Now look at CR6 and you'll see "<-10V" pointing to a pad.  Measure between that point and the center tap.

Mike

 

[rokus666]

Hello,

Something has been bothering me.

What is the sonic difference in using two mono units with "reasonably matched FETs" for stereo operation as opposed to using two units with stereo link with reasonably matched FETs?

Lets say I am recording drum overheads...and have two mono units with similar settings...

How would that affect the stereo image without stereo linking two units???

 

[Echo North]

Hello,

Something has been bothering me.

What is the sonic difference in using two mono units with "reasonably matched FETs" for stereo operation as opposed to using two units with stereo link with reasonably matched FETs?

Lets say I am recording drum overheads...and have two mono units with similar settings...

How would that affect the stereo image without stereo linking two units???

The issue is that without the a link board the units would be compressing at different times and levels.  If the crash under the left side was hit, the left comp would compress hard and maybe the right comp would barely react.  So you've got varying gain reduction reacting on each channel which would sound off.

The link board takes the signals in each side chain (that control GR) and sums them into one signal.  The summed signal is then fed into both comps so GR is equal on both sides.  Big crash on one side, both comps reduce the overall gain a little and keep the stereo image in tact.

Mike

 

[andydiy]

Hi!

I am a DIY Primary .

I have direct at Hairball Audio & MNATS purchased 1176LN Revision D Boards PCB.

You Expert,  can you been introduced into the good Hook, up Wire?

For example: internal the PCB to The Power wire / PCB the the To the XLR wire and so on.

thickness how much it?

Sommer can it?

Thank you!

 

[HMPS]

Ok my power rails look good!  I was measuring from star ground to the point instead of black to point.

Now for these trannies....

The HFE of these seems low, I know Hairball said that they'd be good,
however they measure the same on two different meters.

These are my numbers

209,233,232,223,226,225,222,221,223,229,222,229,221,219223,219,226,231,218,219,222

according to the directions

"Q7 through Q10 must be selected for an hFE of 250 or above. Additional transistor footprints have also been provided to allow for the substitution of alternate devices for Q3, Q5, Q7-10, Q12 and Q13 such as the 2N5088 used in the Purple Audio MC76. The 2N5088 typically has a higher beta than the 2N3707 in the samples I've tested. Another alternative is the 2N3708 which are selected for high beta."

Should I order more from mouser?

HMPS

 

[dmp]

I was measuring from star ground to the point instead of black to point.

You'll want to connect your audio ground to star ground...

 

[Echo North]

You could order more, but that seems really weird that they are that low.  I've never seen one below 250.

 

[HMPS]

Meanwhile wiring and ratio board, pots

I have pots with markings B25K & B5M

Should these be used for attack & release pots?  If I use these do I still need to attach a 25k resistr +.022uf cap & 5M resistor?

Thanks folks!

 

[rokus666]

also,

is it advisable to put all the transistors on 1176's PCB in 3 pin sockets  so that way you can swipe them.

What are the disadvantages instead soldering them directly...

So I went to radioshack and got a 50$ multimeter.

on HFE setting, I have measured 20 pieces of 2n3708 bipolar transistors.

1176 rev d guide recommends transistors from above 250 hfe.

All my 20 trannies measured 210-221 hfe

on my other chinese ebay multimeter they measure 1000- 1010

Am I doing anything wrong? 

 

[rokus666]

Ok my power rails look good!  I was measuring from star ground to the point instead of black to point.

Now for these trannies....

The HFE of these seems low, I know Hairball said that they'd be good,
however they measure the same on two different meters.

These are my numbers

209,233,232,223,226,225,222,221,223,229,222,229,221,219223,219,226,231,218,219,222

according to the directions


HMPS

Very same problem here today!!!

maybe their recent batch has those values ??

 

[HMPS]

What part #'s you using for sockets?

 

[rokus666]

What part #'s you using for sockets?

none yet. I should probably put the sockets on all transistors on PCB

I am still trying to figure everything out. Rolling up my sleeves and ready to learn everything it takes.

Should I just try 2N5088???  What capacitors should I change for these?

 

[rokus666]

Actually I am just checking mouser stock and they have 2n3707 transistors in stock.

The price is 0.77 per 25 pcs...

I might as well do this and see if I will get the desired values...