looking for a discrete transistor parametric circuit diagram

[strombort]

hello
my name is strom , i'm looking to build an audio parametric equaliser with variable 'q' and hi /low shelves.i'm looking for a single rail transistor design tha t can operate on +20v or more.no inductors unless simulated.
thankyou for any assistance in advance :grin:

 

[SSLtech]

...you don't ask much, do you?

I doubt that such a thing has ever been built, and I doubt that such a thing ever will be built.

I've never seen inductors in a parametric EQ that I can call to mind, either.

Keith

 

[strombort]

you've never seen inductors in a parametric?simulated inductors?
tha's what i mean , i'd prefer not to use inductors even though i know of simulated inductance using op amps . but i haven't seen any circuits for discrete eq ( solid state ) parametric that is.

 

[bcarso]

You can make low-mid Q boost/cut allpass circuits out of emitter followers with some success (you need at least one additional Q for boost), although they are difficult to adjust. For your request in general, I would just look at the circuits of some decent parametric EQ boxes and substitute discrete op amps in place of the ICs, if that is really what you want.

If you're going to do that I would take advantage of the generally higher breakdown voltages of the discretes and run with dual rails. They make life easier all around.

 

[strombort]

I'm thinking of an op-amp equalizer operated on single rail here.

That's more like it but could the op-amps be discrete?and concise?

Sorry , maybe i'm asking for too much here. :?

 

[strombort]

You can make low-mid Q boost/cut allpass circuits out of emitter followers with some success (you need at least one additional Q for boost), although they are difficult to adjust. For your request in general, I would just look at the circuits of some decent parametric EQ boxes and substitute discrete op amps in place of the ICs, if that is really what you want.

If you're going to do that I would take advantage of the generally higher breakdown voltages of the discretes and run with dual rails. They make life easier all around.

Good ideas there. Thanks ! :guinness: :thumb:

 

[SSLtech]

Well, to summarise, You're asking for a discrete version of something that only really became practical with op-amps. Simulated inductors also most commonly use op-amps.

If you're determined to avoid op-amps (lord knows why) then the task becomes rather unneccesarily difficult. That's very possibly why there probably aren't any out there that I know of?

I'm curious as to why a complicated device like a fully parametric EQ needs to be confined to the strictures of a single rail supply and fully discrete design...

Keith

 

[clintrubber]

Maybe I haven't read accurately enough,
but wasn't the Trident EQ (CB9066) quite close
to the question in the first post ?

Circuit here probably - or was it back at the old place that this came up ?
Bo Hansen posted it.

 

[StephenGiles]

I bet this guy isn't married!!! His wife would go ballistic at the time he's going to spend on what he wants!!
Stephen

 

[clintrubber]

I bet this guy isn't married!!!

You mean he's not wanting to compromise on anything on his wishlist ? :wink:

 

[soundguy]

I think the trident would work but Im fairly sure the power is 24vdc. I think there was only a partial bit of the schematic posted here. That would be a great project for the lab.

dave

 

[clintrubber]

from strom:

+20v or more

Can't remember if the Trident has hi/lo-shelves, but apart from that all seems as wished for.

Oops, that Trident uses +45V single rail.
I'll upload what I saved from back then and/or got from Bo (thanks Bo !).

 

[clintrubber]

Here we are, Trident CB9066 as far as I have it:

http://home.hetnet.nl/~chickennerdpig/FILES/CB9066/TridentParamEQ.jpg
http://home.hetnet.nl/~chickennerdpig/FILES/CB9066/TridentParamEQSch-A.jpg
http://home.hetnet.nl/~chickennerdpig/FILES/CB9066/TridentParamEQSch-B.jpg

 

[soundguy]

links no worky.

dave

 

[clintrubber]

Was correcting them while you posted, they should be OK now.

(Note the mentioned HPF & LPF are not present in the schematic.)

Cheers,

Peter

 

[soundguy]

we should try to get a complete schematic, this would make a great project.

dave

 

[clintrubber]

For more info/additional schematics first thoughts go towards Bo.

But I'm not sure, I thought it was stated that while discrete & all that, these were not really special w.r.t. sound. I may be very well wrong here, but I thought I recalled s'thing like that.
Being discrete isn't a guarantee for anything of course - maybe this unit demonstrated that ? But again, just vague recollections.

 

[soundguy]

hmm. I have a b range eq here which is fantastically awesome, althogh not parametric. Ive never used one of those but figured there might be some similarity. Id build one on perf just to check it out if we could get the whole schem.

dave

 

[clintrubber]

hmm.

As said, just from vague recollection. So I might very well be spoiling the fun needlessly. Maybe Bo can chime in, I just happened to have saved those schematics and know little more of that unit.
It just came up when discussing that other Trident -unit (CB9146 compressor).

Bye,
Peter

 

[SSLtech]

Well, I'm definately very surprised!

Is that section in the links parametric? -It didn't look like it to me; none the less I never knew of any parametric discrete eq's.

I sit corrected!

Keith