OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby Junction » Wed Nov 04, 2015 7:39 pm

I am afraid my Optro 302 is a very different beast, 6 circuit boards, all discrete components and two big plastic blocks of secret components that contain the fairy dust.
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby Chris H » Wed Nov 04, 2015 9:34 pm

Apparently its not too difficult to get rid of the "plastic box", i think it's a form of epoxy resin, to expose the components without damaging them. I will speak to Allan tomorrow to get info. I'll also ask him if he would be interested in joining the forum so some of his Optro knowledge could be shared.
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby custom acoustics » Thu Nov 12, 2015 2:52 am

Gday Optronic Resurrection Team

Put me down for a t-shirt

Keep the legacy alive :-B
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby custom acoustics » Thu Nov 12, 2015 3:19 am

And if anyone has schematics for a 738 comp/pre/eq or even heard of it.
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby EvLoutonian » Thu Nov 12, 2015 11:52 am

custom acoustics wrote:And if anyone has schematics for a 738 comp/pre/eq or even heard of it.


Is this something you own or have some pictures of?
From the sound of it, it's quite probably not too dissimilar from the 740?
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby custom acoustics » Thu Nov 12, 2015 2:55 pm

Yes I have had this for about 15 years the comp died but everything else is ok.
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby Paul Maybury » Tue Nov 17, 2015 1:56 pm

A BROWN faced Optro module?
Never seen one of those before...
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby original_min » Wed Jan 27, 2016 1:46 pm

I have a black module and power supply like the brown one above.
The bass eq is awesome but it's MF is very tweaky sounding, pretty sure the HF is beyond human hearing or at least mine, the compressor is mostly useless and the whole thing is quite noisy.
Is that normal?
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby Chris H » Wed Jan 27, 2016 2:00 pm

original_min wrote:I have a black module and power supply like the brown one above.
The bass eq is awesome but it's MF is very tweaky sounding, pretty sure the HF is beyond human hearing or at least mine, the compressor is mostly useless and the whole thing is quite noisy.
Is that normal?

Not normal at all. It should have good noise specs. It's a bit hard to tell what module you have, the mids on mine are boost only pot with a selectable range of foxed frequenciers on the 2nt pot.Bass and highs are cut and boost with the highs being very useable and the mids extenting into what most would call highs with a very useable, around 7k boost for the mids that can be great for that breathy close miced vox sound when used with the compressor. Overall a great sounding and versatile module.
Post a pic....maybe it's a different module?

Snapshot 2011.jpg
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby Paul Maybury » Wed Jan 27, 2016 3:35 pm

My silver modules like Chris H's have the same kind of quirks as original min's. Apart from the noise. They have crazy amounts of gain, but I wouldn't call them noisy.
I quite like the mids boost, it is occasionally great on a snare or guitar. The optical limiter/ compressor is VERY slow but if it is just tickled, can be nice on bass guitar or synthy stuff.

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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby original_min » Thu Jan 28, 2016 9:23 am

Interesting...
I've been effin' and jeffin' about this thing for years and never quite known what to do with it.
Might try wire up the line input, I've only ever heard the mic input padded down for line level.
Here are some snaps of it.

IMG_1560.JPG

IMG_1555.JPG

IMG_1558.JPG
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby Chris H » Thu Jan 28, 2016 11:00 am

ere is a pic of the innards of mine. They seem very similar but it looks like your pinouts are wired differently.

optro module.jpeg
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby original_min » Sat Feb 20, 2016 9:02 am

Fixed up the noise, sounds pretty good.
Has anyone experimented with changing the compressor ratios?
(Pretty sure Serge said you can change the globe to do that but could be wrong.)

The low end is very nice but the mid-eq is quite intense, maybe it's useful like that, not sure.
Wondering if anyone has changed the width or anything...
:)
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Re: OPTRO club "PROGRAM EQ" ?

Postby EvLoutonian » Thu Jul 14, 2016 2:33 am

Still watching the letter box for my OPTRO T-shirt..

Meantime, has anyone seen or used the old OPTRO "Program Equalizer" (inductor EQ) unit?
Apparently it's based on the Pultec (solid-state version, presumably) but has a few more freq points.

Keen to hear any thoughts or experiences.
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Re: OPTRO club "PROGRAM EQ" ?

Postby Chris H » Thu Jul 14, 2016 10:20 am

EvLoutonian wrote:Still watching the letter box for my OPTRO T-shirt..

Meantime, has anyone seen or used the old OPTRO "Program Equalizer" (inductor EQ) unit?
Apparently it's based on the Pultec (solid-state version, presumably) but has a few more freq points.

Keen to hear any thoughts or experiences.


Yes, I haven't used a Pultec EQP1A to give an informed comparison with the optro but thy are what you would expect from a good inductor pultec type eq and i suppose they would be more like the pultecs with the API make up gain stage than the valve one as the optro is discreet transistor make up gain amp. This isn't a big issue of transistor verses valve as its not the valves that give the pultec it's main strengths and uses but rather the inductor topology together with cutting and boosting so as to screw with the shape of the eq curves that can be obtained. I used to have a basic Trident VFM console that only had cut and boost high and low shelf with a wide notch mid bell curve cut / boost. With the limitation of not having the option a parametric i was initially prejudiced but after screwing around with the limited options i was amazed at what could be achieved with this simple limited eq, often so much nicer than going straight to the traditional parametric mid sweep option before giving other options a shot and finding out there is a whole new palette of options. Same with the old Hill desk that used to be in the Espy front room. So I suppose what i'm sayin is the optro is just another option to be explored and used where it works, Vox, bass, kick although i do love my silver optros on vox because of their comps characteristics. I have a pic somewhere i will post when i find it.
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby Paul Maybury » Thu Jul 14, 2016 11:51 am

Hi, I use one of these a lot, no inductor but you can do all the main Pultec PEQ tricks with it.
http://www.overstayeraudio.com/ampeq-02/
I would love to hear the Optro version of a PEQ.
I love my Optro graphics and channel strips.
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Re: OPTRO PROGRAM EQ

Postby EvLoutonian » Thu Jul 14, 2016 11:53 am

Thanks Chris.
Sounds great!
Is your's the 3RU version with high and low bands, selectable across 6 or 8 freq's on each side?
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby Chris H » Thu Jul 14, 2016 1:18 pm

Yes, here's the pic we took when re arranging the outboard.
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Re: OPTRO 740 comp / EQ doc's / schemo's ? (WANTED)

Postby EvLoutonian » Thu Jul 14, 2016 1:35 pm

That's the one.. Looks veerrrrrry Pultec-like, in functional terms.

Paul, the Overstayer looks like a great unit, too!
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