simple parametric per channel

Hi,
I am using mic preamp right before digitalizing my audio signals into my MOTU 828. That's very classical configuration.
Often I only need one parametric eq right after the preamp and right before the sound card.
I was trying to find some device that would only hold one parametric eq per channel and have say 8 channels on a 2U rack.
I could not find any.
I wanted to see what you folks thought about this, if you have any device that you know you could direct me to or if you think it would be worthy to create them myself.

Thanks
Alex

not quite sure i know what you mean by one parametric... do you mean one band or one whole EQ? Either way i'd probably look at the Urei 546 EQ. the Parametric section is identical for low, low-mid, high-mid and high except for the switching of about five capacitors (if my memory serves me).

you could build eight bands and have it switchable so that it could act as eight 1 band EQs with the frequency range switchable (you would need 8 input amps but thats not a problem... variable superbal to the rescue). maybe have a link switch incase you need two bands or even all eight for various situations. maybe you could sum all of the bands (when used individually and not linked) into a little internal mixing network so that you only need one beefy output stage. You also wouldn't waste precious electronics by commiting a full fourband EQ when you only need one band.

...AND... when linking up say two bands, you could still use the spare input section that isn't being used on the second band for something (level change or simply deballancing or something) and send it to the internal mixer channel that the second band now isn't using. could be useful for something and again maximising your bang per buck. (god... i'm so cheap!!)

Just an idea i've been thinkin about lately.

http://www.jblproservice.com/pdf/Vintage%20JBL-UREI%20Electronics/UREI-546.pdf

This is exactly the type of project I've been thinking about lately...I love the idea of linking single bands, but leaving each its own i/o capability.

When you say that each would need its own input amp, what would be appropriate? There's a studio close by with some transformerless quad 8's that sound amazing. I need to look at the amps in that circuit again...

Great project idea...

input amp.. there are a lot of questions to be answered here. do you want balanced or unbalanced, do you want transformers or silicon, discrete or IC, etc..

HI,
thanks for your answer, well what I need is to be able to stick a one band parametric whenever I need after my preamp stages, so I guess, they need to take balanced input.
I would love to do them myself but right now I have a bunch of other things to do andI am in urgent need of them, so I am just looking at the possibilities among what already exits.
Yes, the urei, I have been told about it but it is not that compact AFAIK and quite almost difficult to get.
Does anyone know about the dbx 905 module ? anygood ?
thanks
Alex

here is a parametric eq I was working on several years ago..



the Schem is straight for the S0undcraft gh0st.

I even made another board revision, but ive shelved it for a bit..



It sounds great, prob better than the original, maybe because I used BB4134's. Oh, and the rev log pots i got from harman, as replacement parts.

I could post the board layout, if anyone is interested


[/img]

some schematics ? oh yes please.

here is the original gh0st schems... grab them fast, i will not leave them up forever...

Many thanks for the schem. :grin:

[quote author="shmuu102"]
I could post the board layout, if anyone is interested
[/quote]

Yes, please do.
:guinness: :guinness: :guinness:

chrissugar

alexidoia - not sure whats out there that'd be suitable.
i'd probably look at the API lunchbox modules or something. sorry... not much help.

thearnicasync - already made my input amp suggestion,
"you would need 8 input amps but thats not a problem... variable
superbal to the rescue" do a search here on superbal or variable
superbal, i think it's a pretty neat circuit for de-ballancing with
variable gain (thanks TedF) . could also be ballanced in
ballanced out with good CMRR.

Any chance for a re-up?

This is a very old thread, but I didn't answer this last time.  The problem with making a single band of parametric cover the entire audio range band is that putting 1000:1 on a single pot sweep will make frequency adjustment difficult.  Perhaps a 3 position range switch would make this more reasonable.

FWIW I have put 3 band and 4 band parametric EQ in consoles never a single. 

JR