Designing a DIY Multi-Channel Preamp/mixer for Stereo Output instruments.

[zaubertuba]

Another question about that parametric:

Do I really *need* 4 bands? If I replace both the input buffer and makeup stages with jfets, then I'd only need to use one dual opamp. You could just widen the sweep of the midband control-or perhaps widen it and knock it up a little and increase the top range of the bass sweep.

 

[ric3xrt]

Where did you leave off with this, I'm curious as to how far you got with this project?

 

[evil1603]

Me too, since I'm a NS/Stick player myself.

 

[washburn_it]

I'm building my own pre+8 bands equalizer+2-way electronic crossover.
I'm going to use it to go bi-amp with two amp heads (one for the 6.5" midranges and one for the woofers of my two DIY 2x10", or one for a 6.5" and the other with a 1x15" tweeterless).
Actually I'm not using a preamp but the input is directly to the 8 bands eq. (Rod Elliott P84 project, from 63 Hz to 8000 Hz) then to the electronic crossover (Rod Elliot P09 project, mono version).
I've already tested the equalizer alone and it sounded really good with my Yamaha TRB5-II and my head (with the tone control switched off), it added (finally) the right "brightness" to the sound of my bass since it is a bit "dark" (that is a known issue of that bass guitar).
So I suggest you to give that equalizer a try, if you want something more that a classic tone control.

Everything will be managed by a digital board (developed by myself) that through a small touchscreen can store the tone settings of the equalizer, more or less like the TC BH500, and, in the future, also adjust the crossover frequency to make it variable.

Regards,

Roberto

 

[zaubertuba]

Where did you leave off with this, I'm curious as to how far you got with this project?

Me too, since I'm a NS/Stick player myself.

LOL--Sorry Guys! Summer was so busy I never saw those posts--and work's been really busy since then.

Update: I built up the PS and the JISBOS buffers (and proceeded to fry the first buffer when I had my voltmeter on the wrong scale and over-biased it. ). Built a proto-board with a solderless breadboard on it--and subsequently realized wireless breadboard is a poor medium to prototype high-speed opamp circuits. Prototyping on perfboard is maddeningly slow by comparison (especially when time's tight), but it's way easier to troubleshoot without the variables of stray capacitance and dubious continuity.

AMB updated the JISBOS (The α20 Line Stage Amplifier) so you can now add gain up to about 26 dB, so I ordered a bunch of those boards and am working on building up two to play with.

I also have a new architecture I'm playing with--more along the lines of a Modular (possibly internally balanced?) Matrix mixer. More parts, but simpler to implement and in the end wayy more flexible. I'll post some more thoughts and pics when I have time!

Evil--great to see a fellow NS-Player on here!

I'm building my own pre+8 bands equalizer+2-way electronic crossover.
I'm going to use it to go bi-amp with two amp heads (one for the 6.5" midranges and one for the woofers of my two DIY 2x10", or one for a 6.5" and the other with a 1x15" tweeterless).
Actually I'm not using a preamp but the input is directly to the 8 bands eq. (Rod Elliott P84 project, from 63 Hz to 8000 Hz) then to the electronic crossover (Rod Elliot P09 project, mono version).
I've already tested the equalizer alone and it sounded really good with my Yamaha TRB5-II and my head (with the tone control switched off), it added (finally) the right "brightness" to the sound of my bass since it is a bit "dark" (that is a known issue of that bass guitar).
So I suggest you to give that equalizer a try, if you want something more that a classic tone control.

Everything will be managed by a digital board (developed by myself) that through a small touchscreen can store the tone settings of the equalizer, more or less like the TC BH500, and, in the future, also adjust the crossover frequency to make it variable.

Regards,

Roberto

Sounds like an awesome project--I'll have to check out that eq!

Have you looked at using arduino for part of your digital interface? ..or are you building from scratch?

 

[Passinwind]

My bad. I lifted this straight out of my LTSpice model, which doesn't support pots except by drawing a pot as two resistors.

Pardon the necro-bump, but I have a few different pot models for LTSpice, many of which I found on the Yahoo forum.

Thanks for the update Zaub. I'm in the middle of a tube preamp build at the moment, I'll post a thread soon.

 

[washburn_it]

I built that interface from scratch (thanks to a friend) for a totally different kind of project (flight simulation) getting pretty experienced with microcontroller programming (I'm a software developer) so I converted the firmware of the board (basically a 32 I/O lines board) for audio purpose.
My "digital controlled bass preamp" is "on hold" at the moment but hopefully I'm going to complete it in a short time.
It will include also a Class-D power amp (AudioPower.it) dedicated to drive the midrange if used "bi-amp" with one of the bigger cabs, or as standalone amp to play with the guys at the room.

Regards,

Roberto