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Williams Audio 25th May 2011 07:32 PM

acoustat 3
 
hi
there is a question that is troubling me for some time
i own an acoustat 3, the xover has two sections connected together at input, one for low and one for hi
disconnecting this junction and connect it each one to a separate pwr amp will be equal like doubling the pwr, driving the low and hi separately
each amp will deal with an easier load and impedance
so, i will have to use two stereo pwr amps, whether someone tried this?
is a good idea?
best regards,
Williams

AcoustatAnswerMan 31st May 2011 06:50 PM

Quote:

Originally Posted by Williams Audio (Post 2583452)
hi
there is a question that is troubling me for some time
i own an acoustat 3, the xover has two sections connected together at input, one for low and one for hi
disconnecting this junction and connect it each one to a separate pwr amp will be equal like doubling the pwr, driving the low and hi separately
each amp will deal with an easier load and impedance
so, i will have to use two stereo pwr amps, whether someone tried this?
is a good idea?
best regards,
Williams

This question surfaces frequently. The hi and low frequency transformers overlap considerably in frequency range, so the traditional method of bi-amping 'tweeter' and 'woofer' do not really apply here. Sure, some people have tried it, but I have never heard of anyone finding that it was a significant improvement. I wouldn't bother pursuing this idea.

If you need more power, a larger single amplifier channel is really the only wa to go.

Williams Audio 1st June 2011 04:43 PM

hi acoustatman
well, thanks for the answer
but, maybe it is not fully certain, i will test this soon
best regards,
williams

fdlsys 23rd July 2012 11:30 AM

Quote:

Originally Posted by AcoustatAnswerMan (Post 2590263)
This question surfaces frequently. If you need more power, a larger single amplifier channel is really the only wa to go.

Hmmm, for argument sake, what if I have a limitation of the per-channel pwr? I have built perfectly behaved 25W/Channel DIY class-A (Pass F5) amps, but going higer than that per channel poses serious logistical/mechanical challenges.

However, bi-amping using 2 of those (2x25W per channel) is as easy as pie.

Furthermore, I would expect that any impedance shifts and current draw irregularities resulting from driving the panel full-range where one section of the xover affects the other would be minimised (for the given xover design)?

Finally, splitting the parallel xover into 2 would result in each part appearing as a higher impedance load to the amp, which is not a bad thing at all, right?

Personally, I am not after more power at all - I get all the SPL that I need from the said 25W per channel (full-range). However, I would not mind a bit more control in the lower Fq region, and I am hoping that throwing more current (reserve) at it might help, and bi-amping sounds like the quickest way to achieve that.

Should I expect any problems?

Thanks, Mike

john65b 23rd July 2012 12:07 PM

fdlsys:

Can you Bridge the F5's for more power?

I have Icepower 1000ASP running my Model 3's and the LF really sings with all that power....25 wpc really won't do it. Although my Krell Clone (50 - 60 wpc ) sounds even better on the model 3...probably due to the 1.2KV tranny and 136kuf capacitance per side...tons of current...

I have a similar issue, as I really like the low frequency end of the Model 3 I have, but really want the high frequency of my ML CLS Panels...I am thinking of taking the mid panel off the Model 3 and replacing with the CLS panel... a hybrid ESL...

Sorry to digress the thread...

fdlsys 23rd July 2012 06:21 PM

Quote:

Originally Posted by john65b (Post 3101480)
fdlsys:
Can you Bridge the F5's for more power?

Nope. Plus, bridging an amp is really not a good idea - at least because the minimum impedance that one can safely drive from the bridged amp is twice the individual channel, not to mention consequences of two less than perfectly equal channels working "against" each other.

Balanced output amp, different story. However, that poses the same physical (and financial) challenges as pushing more power out of the existing design.

F5 design and variations are great as-is, don't want to mess with it.

Williams Audio 23rd July 2012 07:21 PM

hi all,
i do not agree that a small amp that is will drive it to a point that say is a great sound, i use a 150 watts/channel and is not the very best.
a good reference is this : http://sanderssoundsystems.com/techn...vs-transistors.
best regards
williams

fdlsys 23rd July 2012 07:54 PM

Quote:

Originally Posted by Williams Audio (Post 3101948)
hi all,
i do not agree that a small amp that is will drive it to a point that say is a great sound, i use a 150 watts/channel and is not the very best.
a good reference is this : Tubes vs. Transistors White Paper.
best regards
williams

Apples and oranges, I'm afraid. But lets agree to disagree, shall we?

The original (your) question was about bi-amping the xover low and high.
You said you will test it - may I ask if you did, and what were the results?
Regards,
Mike

john65b 23rd July 2012 09:12 PM

Quote:

hi all, i do not agree that a small amp that is will drive it to a point that say is a great sound, i use a 150 watts/channel and is not the very best.
There are plenty out there who drive their atrocious (difficult load, not sounding) Apogee speakers with 25wpc Mark Levinson ML-2 amps...may not get extremely loud....

Yes, Bridging any amp with Acoustats (or any other ESL) would halve an already very low impedance - forget I suggested such a thing...

bear 23rd July 2012 10:12 PM

The Acoustat 121 interface, afaik dips only to about 6 ohms.

There is an X version and a turbo version of the F5, worth considering.

The Acoustat eats voltage swing for lunch. That translates to a high rail voltage, which means for a transistor amp a high power amp.

Otoh, I heard IIIs in the 70s sound really pretty fabulous running on a Bedini 25... but in general they want swing.

The best I have heard mine with was with a pair of tube amps that ran 2 x 811a, really great stuff. I plan to return to that if i ever get to that project...

_-_-bear


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