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[Jack Daniels]

Does anyone have the pin out for the 8995 or 8990 EQ from McCurdy?  This is an opamp base EQ.

Thanks

Joe

[Geoff Doane]

Jack Daniels wrote on Tue, 15 November 2005 18:18

Does anyone have the pin out for the 8995 or 8990 EQ from McCurdy?

That brings back bad memories   .

Here goes (for the 8995):

Input: 1,2(3) +,-(SH)

Output: 10,11

Power: 4,6,8  (+25V, COM, -25V)

Chassis: 9

The letter side of the connector isn't used

This info from a McCurdy manual dated April 26, 1982.

Geoff

[Jack Daniels]

Thanks so much!  I just got a pair and am guessing from your post that they are not so good?

I actually wanted 155's but bid on the wrong ones on ebay.  I picked up a pair of these for 45 bucks. So I am going to rack them anyway.  Now that I know they are also 25 +/- like the others, I will build a rack large enough for the other style too.  I was hoping to get 4 of the 155's.

THanks again.

JD

[Geoff Doane]

It's a pretty basic EQ module and is aimed at the broadcast market.  It would normally be used in consoles that had no EQ at all, so anyone used to a recording console would find them very limiting.  As I recall, the biggest problem with them from a service perspective is the switches (particularly the bypass) would not pass audio reliably after a few years.  You might be better off wiring them out.

You don't really need +/- 25V to run the module.  The first thing the 25V hits is a pair of regulators, taking the voltage down to 18V.  If you bypassed the regulators, and ran the module from +/- 15V, you'd be OK.  McCurdy consoles of that era ran on +/- 25V so these modules had to handle that.

I think the basic design of the EQ is sound. It uses 5534 op-amps, although there are a lot of electrolytics in there (in the audio path) that you might want to change, considering the age of the thing.

We had three SS8800 series consoles in daily use for over ten years, and they were very reliable.  McCurdy used all electronic switching in the audio paths, EXCEPT for those darn EQs, and that was what gave us the most trouble.

Geoff

[Jack Daniels]

HI Geoff,

If you stop by to read this, I have a question for you.

You listed pins 1, 2 and 3 as input.  Would this be balanced:

1 High
2 low
3 shield ground

or is this unbalanced

1 +
2 Ground or -
3 shield tied to ground?

also you listed that pins 10 and 11 are outputs.

Should I assume 10 is + and 11 is -?  and is this balanced or unballanced too?

I think most of the time eq modules are not ballanced (API) but every once in awhile I see them ballanced too.

JOe

[Geoff Doane]

Jack Daniels wrote on Sat, 19 November 2005 16:09

1 High 2 low 3 shield ground also you listed that pins 10 and 11 are outputs. Should I assume 10 is + and 11 is -?  and is this balanced or unballanced too? I think most of the time eq modules are not ballanced (API) but every once in awhile I see them ballanced too.

Your assumptions are correct.  I should have been a bit clearer, I guess.  Pin 3 is likely signal ground, and in keeping with modern practice, the shield should probably go to chassis ground instead.  All the McCurdy broadcast stuff I've worked with has been balanced, in and out.  In the old days it was done with transformers, and this newer stuff has differential outputs using NE5534s.  The consoles were mostly custom jobs that used McCurdy's different off-the-shelf modules, all bolted into a frame, and wired up to terminal blocks and power supplies.  Since it was all balanced, you could put them together in any order, and through patch bays, and it would still work and be quiet.

Geoff

[Jack Daniels]

Thanks you have been a great help!  Happy Holidays.

JD