frankenboard?

P

producerkid

New member
Okay, so not sure where to put this thread so it's going here.

I recently acquired a Biamp 1229 12 channel powered PA mixer. FREE.

So i'm going to chop it up and tear it apart and mod it into a recording console. Any thoughts? (I don't wanna hear "it'll never be worth it", or "that's stupid"). You're probably right anyway, but this board has no other purpose then to get turned into an experiment.

That being said, here's the details:

The board is in perfect working condition, with minor scratchy pots and a few bad solder joints in the P.S. (fixed) This board has 12 individual channel modules with three band EQ (L,M,H) and a nine band EQ for both the MONITOR bus and the MAINS bus (2x9 bands). The board is set up mono on the master outs (mains, monitor). There are two subgroups of which the channels are setup to pan to (sub1, sub2). The subs are then summed to the mono MAINS master channel and there are MONITOR sends on each channel which sum to the MONITOR master channel (duh). There is also of course an FX send on each channel next to the MONITOR channel (aux1, aux2 anyone?).

How I want to setup the board:

I am going to leave the MAINS master configuration intact. I will setup the MONITOR master fader as a permanent talkback/utility fader (make an insert point between the channel monitor sends and the monitor fader and patch out to one of the jacks on rear panel). This channel will be sent to the auxiliary in of my headphone amp. I will also setup the FX sends and MONITOR sends to show up side by side on two of the return summing pots (this sent to main input on headphone). I would also like to implement solo and mute abilities to the board.

Things that need to happen with the board (in no particular order):

1) Remove internal power supply and build into external chassis connected by a pigtail (five pin din?)

2) Remove power amplifier units alltogether (later project maybe).

3) Recap and clean controls on all channels

4) Rebuild (modify) P.S.

5) Reroute board for new setup (the fun part).

6) Design and implement soloing and muting for each channel.

7) Add phase inversion on each channel.

8) Remove reverb tank.

As you can see, this will probably be an ongoing project for some time. My main objecives are to use the board primarily for summing. Mixdown summing using the individual SUB outs on the back (my subs will be the new LEFT and RIGHT master channels) and channel summing for guitar tracking, double micing drums, etc. I would probably never use the preamps unless it was for something totally non-critical or maybe for quick live one-offs straight to cd.

I believe by moving the power supply outside of the unit, getting rid of the power amps, rewiring, and double-insulating everything I should be able to get the thing virtually noiseless. Not to mention overhauling the channels.

The main areas I need help in are finding schematics for the damn thing, and I need some suggestions for the solo/mute circuit. I'm thinking optocouplers fed by the B+ line off the power supply and controld by a small toggle on each channel. I'm assuming adding phase inversion should be pretty easily done through toggle switching? Or would optos be cleaner for this?

Any SERIOUS suggestions would be awesome. I'm really just wanting to share this as a giggle for everyone else and a part time project for anyone else that cares. If the results are good I'll be posting some sounds.
 
producerkid said:
Okay, so not sure where to put this thread so it's going here.

I recently acquired a Biamp 1229 12 channel powered PA mixer. FREE.

So i'm going to chop it up and tear it apart and mod it into a recording console. Any thoughts? (I don't wanna hear "it'll never be worth it", or "that's stupid"). You're probably right anyway, but this board has no other purpose then to get turned into an experiment.

That being said, here's the details:

The board is in perfect working condition, with minor scratchy pots and a few bad solder joints in the P.S. (fixed) This board has 12 individual channel modules with three band EQ (L,M,H) and a nine band EQ for both the MONITOR bus and the MAINS bus (2x9 bands). The board is set up mono on the master outs (mains, monitor). There are two subgroups of which the channels are setup to pan to (sub1, sub2). The subs are then summed to the mono MAINS master channel and there are MONITOR sends on each channel which sum to the MONITOR master channel (duh). There is also of course an FX send on each channel next to the MONITOR channel (aux1, aux2 anyone?).

How I want to setup the board:

I am going to leave the MAINS master configuration intact. I will setup the MONITOR master fader as a permanent talkback/utility fader (make an insert point between the channel monitor sends and the monitor fader and patch out to one of the jacks on rear panel). This channel will be sent to the auxiliary in of my headphone amp. I will also setup the FX sends and MONITOR sends to show up side by side on two of the return summing pots (this sent to main input on headphone). I would also like to implement solo and mute abilities to the board.

Things that need to happen with the board (in no particular order):

1) Remove internal power supply and build into external chassis connected by a pigtail (five pin din?)

2) Remove power amplifier units alltogether (later project maybe).

3) Recap and clean controls on all channels

4) Rebuild (modify) P.S.

5) Reroute board for new setup (the fun part).

6) Design and implement soloing and muting for each channel.

7) Add phase inversion on each channel.

8) Remove reverb tank.

As you can see, this will probably be an ongoing project for some time. My main objecives are to use the board primarily for summing. Mixdown summing using the individual SUB outs on the back (my subs will be the new LEFT and RIGHT master channels) and channel summing for guitar tracking, double micing drums, etc. I would probably never use the preamps unless it was for something totally non-critical or maybe for quick live one-offs straight to cd.

I believe by moving the power supply outside of the unit, getting rid of the power amps, rewiring, and double-insulating everything I should be able to get the thing virtually noiseless. Not to mention overhauling the channels.

The main areas I need help in are finding schematics for the damn thing, and I need some suggestions for the solo/mute circuit. I'm thinking optocouplers fed by the B+ line off the power supply and controld by a small toggle on each channel. I'm assuming adding phase inversion should be pretty easily done through toggle switching? Or would optos be cleaner for this?

Any SERIOUS suggestions would be awesome. I'm really just wanting to share this as a giggle for everyone else and a part time project for anyone else that cares. If the results are good I'll be posting some sounds.
Click to expand...

Post a pic when you're finished! This s/b interesting!
 
producerkid said:
8) Remove reverb tank.
Click to expand...
Got any plans for this?
The main areas I need help in are finding schematics for the damn thing, and I need some suggestions for the solo/mute circuit. I'm thinking optocouplers fed by the B+ line off the power supply and controld by a small toggle on each channel. I'm assuming adding phase inversion should be pretty easily done through toggle switching? Or would optos be cleaner for this?
Click to expand...

Problem with Vactrol type optos is they have resistance (sometimes hundreds of ohms) in the (on) condition. For these applications you want as close to no resistance as possible. Relays or regular switches are best here. Try to get parts with gold plated contacts.
 
some time ago, i did something similar with a monster fender 3206, like this:
fender3206nov.jpg

took the power amps out because they were roasted. actually left the spring tank in there because it wasnt half bad (as spring reverbs go). didnt go so far as the mute and solo buttons. actually, it was beautiful in its application alongside a tascam 424 (i *did* say some time ago). with it and the onboard terrible preamps on the tascam, i could track 8 mics at a time. the preamps were warm with decent headroom, but they were anything but transparent. using the two monitor outs was a little crude in application, but perfectly functional. some of those old tapes really dont sound terrible, especially considering how little i had to work with. i still have it, and do very occasionally use it as a submixer or to add some splashy reverb. mostly, it is the resident dust depot.
a
 
yo som,

you asking if i wanna give the unit up?

i would if thats what you are asking.

spring reverb is a cool effect but not really my cup of tea unless its something specialty. in which case i use a guitar amp with a decent spring verb.

ive searched around a bit and cant find any free schematics online. if i have no choice but to pay for one then i will but im trying to avoid that.

thanks for the interest guys.

so by adding the phase swtiching all i should have to do is run two sets of leads off of pins two and three of the XLR jack to a 2 way DPDT switch and reverse one pair of leads on one position of the switch, correct?

something i was thinking about was mute and solo automation by adding a midi interface or via serial port. in which case i could then use (rather have to use) optos to control the relays for M/S via midi?

man itll probly take forever to get all this accomplished but itll be pretty sweet when its done i think

also, to convert something to balanced operation shouldnt be any more difficult than wiring shield to chassis, neutral to - and hot to +? or is it more involved. ive done this before in a noise reduction unit and it seemed to work.
 
producerkid said:
yo som,

you asking if i wanna give the unit up?

i would if thats what you are asking.
Click to expand...
Yeah if you don't need it I have some applications for it. It won't be wasted.

ive searched around a bit and cant find any free schematics online. if i have no choice but to pay for one then i will but im trying to avoid that.
Click to expand...
Try the manufacturer's tech support, assuming the company still exists. Somebody there might send you a scan for free.
thanks for the interest guys.

so by adding the phase swtiching all i should have to do is run two sets of leads off of pins two and three of the XLR jack to a 2 way DPDT switch and reverse one pair of leads on one position of the switch, correct?
Click to expand...
That sounds correct to me. Look at this schematic of my Toa's input channel for an example of how this should be wired.
https://i108.photobucket.com/albums/n13/somnium7/gear/RX7input.jpg
It's on the upper left...
something i was thinking about was mute and solo automation by adding a midi interface or via serial port. in which case i could then use (rather have to use) optos to control the relays for M/S via midi?
Click to expand...
http://www.paia.com/midi2cv.asp
I used one of these for an older synth project. It's prety easy to build and works pretty well. For your app I would set it up for 8 CVs from Continuous Controller operation. Then send 0 or 127 CC messages to turn the outputs on and off.
also, to convert something to balanced operation shouldnt be any more difficult than wiring shield to chassis, neutral to - and hot to +? or is it more involved. ive done this before in a noise reduction unit and it seemed to work.
Click to expand...
To do this properly is more work than that. You'll either have to use transformers or add some opamp circuits for electronic balancing. Here's an example of the electronic balancing:
http://sound.westhost.com/project51.htm
Using transformers is simpler and exhibits better performance but it can get expensive quickly.
 
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Manual/schematics

Biamp still exists and will send you the schematics and manual (for like $10). I have the same board (in an Anvil case in a closet). It served my band well for many years (live and then later as a console in a studio). Good luck with your project.
 
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