Newsgroups: rec.audio
From: smith@eecg.toronto.edu (Michael B. Smith)
Subject: Re: Bi-Amp vs. Bridged Bi-Wire
Organization: Dept. of Electrical Engineering, University of Toronto
Date: 2 Sep 92 22:09:43 GMT

In article <416@bit.UUCP> grego@bit.UUCP (Grego Sanguinetti) writes:
>In article <1992Sep1.212321.9571@jarvis.csri.toronto.edu> smith@eecg.toronto.edu (Michael B. Smith) writes:
>>Assume that you have speakers that can be bi-amped and you happen to
>>have four amps available.  One possible setup would be to bi-amp the
>>speakers (i.e. one amp for the left tweeter, one amp for the left
>>woofer, etc.).  Assuming that your amps can be bridged, it should also
>>be easy to hook these speakers to be only bi-wired, but driven by
>>a bridged amp.  This should provide about double to triple the power,
>>so they'll probably be louder.  But, the big question is, which version
>>should sound "better"?  What are the merits of bi-wiring?
>>
>
>My experience is that it is better to divide the stereo amps by frequency,
>i.e. use one stereo amp to drive L & R woofers and another to drive
>L & R tweeters. This assumes that the two channels of a given stereo amp
>are powered by the same power supply. If the stereo amp is actually a
>"dual mono" job (two distinct power supplies) then it doesn't matter.
>
>Dividing the amps by frequency also alows you to match the amps to the
>purpose. Some amps sound better down low, others have better high end....

Great idea!  All the amps will be NADs, so there respective performance
should be rather similar.  But, this is certainly an area for many long
evenings of moving patch cords around!
>
>Another nice feature is that bi-amping gives you control over the
>cross-over. Presumably there is a passive cross-over filter in your
>speaker cabinets that is bypassed in bi-amp mode. Typically the active
>cross-over filter that you will use in a bi-amp configuration is a faster
>(higher order) filter. This can be good or bad depending on the speakers
>(drivers and box design). Also the cross-over frequencies might be
>different. The good news is that you can choose different filter orders
>and cross-over points, the bad news is that you will have to experiment
>to find out which ones end up sounding the best. There are active systems
>on the market that alow you to adjust frequencies. Some even have
>choices to roll-off rate (different order filter combinations).

After I have the basic system together, I'll be looking into adding something
for this.

>>(This comes from planning a pro-logic system with 10 amps and 5
>>speakers, and wondering what to do with all of the extra amps...)
>>Michael
>
>10 amps eh? Are they all good quality? If not then don't be tempted to
>use them just because you have them. Also be aware that the surge current
>(saturating the transformers and charging the filter capacitors) when
>all 10 amps fire up, is going to be quite large. 10 amplifiers with
>a conservative estimate of 2 amps each at startup is 20 amps. This would
>be typical for 10  100w(total) amplifiers. You might want to rig up
>a R/C delayed relay system to sequence the amps at startup.

10 NADs firing up.... never thought of that.  I guess I really shouldn't
just have one big master power switch!

>sounds like fun.  -grego

Isn't that what it's all about?!
-- 
--
Michael B. Smith					UofT:(416)978-1652
smith@picton.eecg.toronto.edu				Electrical Engineering
--
Time is a great teacher, but unfortunately it kills all its pupils.
Newsgroups: rec.audio