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Old 25th March 2005, 11:25 AM   #1
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Default Sonic Impact bi-amp help

Hey folks,
Well I finally got my t-amps that I ordered months ago. I reckon I could be the only Irish person to have any of these lovely amps!
I decided to rehouse two of them instantly in a bi-amp configuration. This was done, but due to a bit of stupidity two wires were the wrong way around (I was distracted, then only realised why I was getting a "tapping" noise a good while afterwards).. Basically I think I fried one of them (A in the diagram), as when I reconnected it all up properly only one of the amps was working (both had power though).
I'm currently listening to it on it's own and I must say I'm impressed though!
Anyway - before I strip another board, I'd like to know f my circuit diagram is right/feasible as I really dont want to blow another.
Cheers
Mark

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Old 25th March 2005, 01:26 PM   #2
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Old 25th March 2005, 01:44 PM   #3
joensd is offline joensd  Germany
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Hi,
usually real biamping is when you power (letīs say) your tweeter and your midwoofer from separate amplifiers but also feed your amps with a signal coming from an active crossover.

Some passive loudspeakers have an option for biamping but with the passive crossovers still in place.

You have to make clear which way is your intention.

If you want the first option a crossover is missing and obviously you canīt feed both (stereo-)amps with the same signal.

If option 2 is what you want then your diagram should work well enough. (just the 1.5A power supply is definitely too weak for 2 stereo SIīs)

greets
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Old 25th March 2005, 01:49 PM   #4
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Well the plan is to power my B&W 602's which have 4 binding posts per speaker and I know people who have them bi-amped with the Arcam 8r/8p combination (my original plan, but the SI sounds much better then my 8r)..

Theoretically, yes this isnt real bi-amping, but I was looking for a way to increase the power going to the speakers..

Yeah my worry was with the power supply also - I suppose I'd need at least 1A per Amp?
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Old 25th March 2005, 03:00 PM   #5
BWRX is offline BWRX  United States
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you might also want to be careful as your input impedance will be different and varying driving two SI inputs in parallel. changing the position of the potentiometer directly varies the input impedance.

the case looks awesome. all business and very clean. i love that look. any chance we could see some shots of the inside?

ideally it would ideally be better to let each amp have its own supply, but if you're going to have two run off of one it should have a fairly high current capacity (Ah) or you can expect to recharge it quite often.
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Old 25th March 2005, 03:17 PM   #6
joensd is offline joensd  Germany
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Quote:
Theoretically, yes this isnt real bi-amping, but I was looking for a way to increase the power going to the speakers..
Yes, as the B&Wīs arenīt the most efficient you want to get the most out of the SI.

Quote:
Yeah my worry was with the power supply also - I suppose I'd need at least 1A per Amp?
Delivering 1A*12V to the amp you obviously canīt expect to even get 12W (2*6W) out of the amplifier.
If you roughly calculate with 80% efficiency of the SI and want to get 2*10W=20W youīd have to deliver at least 25W to that (one) amplifier which means about 2.1A.
Have a look here. (PSU/AMP3; TA2021 being similar to the TA2024; or take a look in the datasheet of the TA2024 for power requirements as these are just rough calculations)

Being at it: Does anybody how the SI behaves when clipping/running out of "juice"?

greets
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Old 25th March 2005, 03:50 PM   #7
BWRX is offline BWRX  United States
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the peaks of the waveform distort when the output clips. i've seen it on a scope and it's exactly as they describe in one of their apllication notes.

check this link out: http://www.tripath.com/downloads/an6.pdf

for the other app notes go here: http://www.tripath.com/application.htm
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Old 26th March 2005, 08:59 AM   #8
joensd is offline joensd  Germany
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Many thanks for the interesting link!.

Back to Markīs problem.
Do you really think the input impedance is a serious problem with 20k if the CD-Player or whatever is up to the task (which it should)?

Iīd just get the proper power supply together, some Y-cables or so to feed both amps with the same signal and just try it...
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Old 26th March 2005, 10:01 PM   #9
BWRX is offline BWRX  United States
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Quote:
Originally posted by joensd
Do you really think the input impedance is a serious problem with 20k if the CD-Player or whatever is up to the task (which it should)?

Iīd just get the proper power supply together, some Y-cables or so to feed both amps with the same signal and just try it...
if the source is up to driving the lower input impedance then it won't be a problem. i would just test it like you mentioned and find out if it is.

on the topic of biamping, i'm in the process of putting together a dual power supply to power two t-amps and will eventually biamp my speakers. i still have to find or make some sort of preamp/active filtering though to be able to make it a true biamped system.
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Old 27th March 2005, 06:07 AM   #10
joensd is offline joensd  Germany
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Quote:
i still have to find or make some sort of preamp/active filtering though to be able to make it a true biamped system.
You probably know ESPīs projects.
http://sound.westhost.com/projects-3.htm
I tried the 12dB-XO on stripboard and it worked very nice with the drivers I used (TB W3-871S+woofer).
If you donīt mind some more parts go for the 24dB.
In the end I wanted the XO to be adjustable and bought a Behringer CX-2310 which is really nice for the price.
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