hi all,

i have a pair of 35102's v03 and a quad line amp 35302 (trannys are gone but)

i have read the audix threads that allude to the fact that some of these modules have a low headroom output stage. I am hoping that using this module will somehow fix this.

I have been able to find schematics and so on for the 35102's but nothing on the 35302's.

i would appreciate any advice on how to put this all together (35302)
i am thinking of using the JLM power, di and phantom boards...

thanks all


soundguy

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #1 on: May 24, 2006, 12:50:44 PM »
take a gain block from the line amp and stick that after the output to the EQ module with a fader in bewteen.  done.

dave

chips are good with dip...

Rob Flinn

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #2 on: May 24, 2006, 07:23:22 PM »
I have a feeling that I have the diagram somewhere for your line amp.  I is one with 4 gain setting pots on the front & space for 2 transformers near the back, that mount on the pcb ?
regards Rob

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #3 on: May 24, 2006, 08:14:58 PM »
Thanks for your reply guys:

Dave Wrote:
Quote
take a gain block from the line amp and stick that after the output to the EQ module with a fader in bewteen. done.

dave


do you mean after the output 'of' the eq module or after the output of the 'mic pre' and before the 'input' of the eq... sorry im so thick.

Rob wrote:
Quote
I have a feeling that I have the diagram somewhere for your line amp. I is one with 4 gain setting pots on the front & space for 2 transformers near the back, that mount on the pcb ?


yep that's the one Rob.
unfortunately mine has had the transformers removed, but i think they are input trannys so not really needed here.

if you happen to find the diagram it would be much appreciated.

thanks for your knowledge guys and keep it coming.

cheers

soundguy

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #4 on: May 24, 2006, 08:52:00 PM »
Quote from: "spacecho"

do you mean after the output 'of' the eq module or after the output of the 'mic pre' and before the 'input' of the eq... sorry im so thick.


the main output from the pin on the edge connector.

dave

chips are good with dip...

avedis

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #5 on: May 24, 2006, 11:26:53 PM »
I am more familiar with the 35102 and I know that the headroom is not too bad with an output tranny but I'm not sure what it would be if loaded at 600 ohms just for the sake of testing the it.

There are output driver TO39 type transistors there so I'm not sure if you really need a line amp, but the output transformer is external and usually not included when you purchase these modules. I would recommend putting a 1:2 ratio there. The original, I believe, was a Sowter 4127.

The input transformers were Marinairs, but the later versions with the rounded corners.

There's a relay in there that switches the mic to line. Keep that in mind if you get no signal to the IC opamp which serves as the preamp.

If the EQ doesn't work, look for broken wires between the boards. You could have a pinged off wire there and it's hard to see it with all the others around it.

Let us know how it goes!

Avedis
Avedis

Rob Flinn

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #6 on: May 25, 2006, 03:50:51 AM »
The input transformers are Marinair 31267.   I had some of these amps come my way a while back.   I'm fairly sure that I have the diagram somewhere, but it may take some time to find it.
regards Rob

Family Hoof

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #7 on: May 25, 2006, 11:34:16 AM »
Quote from: "avedis"
There are output driver TO39 type transistors there so I'm not sure if you really need a line amp, but the output transformer is external and usually not included when you purchase these modules. I would recommend putting a 1:2 ratio there. The original, I believe, was a Sowter 4127.

Avedis, I know there were a few revisions of this module, and I'm not sure of the differences between them or how the output drive was done in AUdix consoles, but when racking a pair once I discovered that it could not drive an output transformer, as stock. I had a small 1:1 into 600ohms. Within a few minutes the output amp started overheating, the headroom and bandwidth diminished, and there was a ton of distortion at nominal operating levels. Looking on all the schematics and open modules I've seen, there are no TO-39s or other power output device. The output amp, like most of the other amps in the circuit has a single TO-92 device (class A), with a complementary device functioning as the current source. Granted, I can't see how driving 600omhs through a large 1:2 output transformer, like the Sowter, would be feasible. How do you get enough current gain? For the pair I worked on, a additional high-current op amp, e.g. 2520, was added and the output drive problem was solved. I think if I did it again I'd just perf a simple follower.

avedis

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #8 on: May 25, 2006, 02:45:41 PM »
FH - ya know, you're right from what I find on the schematic. It looks like Amp #5 has TO92 transistors in the output stage - obviously not enough to power to drive a 1:2 (150:600) or a 1:1.

I suppost the Audix' I worked on have all had TO-39's in them, and I have seen and worked on a lot of them and have never seen one with 92's on the outputs. I think you're right that they've had different versions/revisions. Now I'm gettin' to think that maybe all one needs to do is replace the output transistors from a TO92 to a TO39; though I have to look at the circuit to see if ac/dc gain is the same (VT152 & VT153)

Maybe I'll check out a 35102 next week and try and make sense of this. This is why this post got me wondering why you'd need a driver.
Avedis

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #9 on: May 25, 2006, 04:53:15 PM »
Hi
You NEED the transformer (or a suitable equivalent) with it's 6dB stepup to get the headroom. The line amp section of the quad amp modules have TO220 transistors (40871 and 40872) to give enough current. The output of the input module will only drive a small current and is at -10dB for nominal input setting. There are 2 outputs indicated on the schematic, one has a single output capacitor and thus may have a slight leakage voltage on it and is used where the signal is not switched. The second has an extra cap to get rid of the slight leakage. This is then used in situations where it is switched. I was testing these things in 1982/3 as I was broadcast test manager then at Audix.
Matt Syson
Matt S


Tillmann

racking a pair of audix 35102 with a 35302 quad amp module?
« Reply #10 on: May 26, 2006, 11:55:57 AM »
Does anyone out there have a revision 3 schematic (not a block diagram or a revision 2) for these that they could send to me?  I've seen that people have been asking for this on the forum for a couple years now and no one has posted a schematic.  I have a very small and poor copy and a lot of values are blurred on it since it's so sh*tty.  I keep reading that everyone has too big of a copy to scan which is just the opposite of my problem.  I would love to get a good copy scanned and if anyone would send it to me I would be happy to do the legwork and post it so everyone that wants it can finally have it.

Cheers!


 

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