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
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.
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
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...
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...
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.
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/technical-white-papers/172-tubes-vs-transistors.
best regards
williams
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/technical-white-papers/172-tubes-vs-transistors.
best regards
williams
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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
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...
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
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
Hi Bear, my apologies for the very late follow up. Many, many projects in the pipeline.
Back on the subject:
You are absolutely right about the Acoustat transformers/xover overlap and the way panels are driven (full range), but the impedance does drop to 3 ohm and that is at rated -2db point (30Hz for Model-3). Lower Fq has not been plotted but the curve looks like dropping off a cliff. Legends say that many "audiophile grade" amps smoked on Acoustats.
Anyway... I have 2 F5s completed and they sing beautifully.
Since it doesn't cost me anything to give it a try, I have taken the interfaces off the M-3s today and had a look - dead easy to split. So we'll know soon. One stereo amp per speaker - that's about as close to identical drive as one can get.
Back on the subject:
You are absolutely right about the Acoustat transformers/xover overlap and the way panels are driven (full range), but the impedance does drop to 3 ohm and that is at rated -2db point (30Hz for Model-3). Lower Fq has not been plotted but the curve looks like dropping off a cliff. Legends say that many "audiophile grade" amps smoked on Acoustats.
Anyway... I have 2 F5s completed and they sing beautifully.
Since it doesn't cost me anything to give it a try, I have taken the interfaces off the M-3s today and had a look - dead easy to split. So we'll know soon. One stereo amp per speaker - that's about as close to identical drive as one can get.
fdlsys, the reason that amps smoke is mostly that the load looks capacitive, causing a phase shift that if the amp is not very stable can cause instability. Of course amps without enough current capability will have trouble no matter what.
I am surprised that you found a dip that low in impedance, I do not recall it being so in the original curve published by acoustat, but I have not looked at that for a long long time, so I guess it is possible... but that low a Z *below* 30Hz. is not likely to have much of an effect for most situations, since most source material has zip, nil, down there, and what it has is mostly transitory and short in duration.
I am surprised the F5s play loud enough, but may they are ok in a small room... happy to hear that they work well... being class A they should be ok, fine.
I am surprised that you found a dip that low in impedance, I do not recall it being so in the original curve published by acoustat, but I have not looked at that for a long long time, so I guess it is possible... but that low a Z *below* 30Hz. is not likely to have much of an effect for most situations, since most source material has zip, nil, down there, and what it has is mostly transitory and short in duration.
I am surprised the F5s play loud enough, but may they are ok in a small room... happy to hear that they work well... being class A they should be ok, fine.
@John65b: Agh, the plan was this weekend, but that plan has taken a dive due to reoccurring electrical and other problems following the monster hail storm we had last week. Fixing the problems and hopefully securing the house against similar disasters takes precedence.
@Bear: For my room ("L" shaped 32sqm, with speakers along the shorter 3.6m wall playing into the 6.5m long part of the "L") and my liking, even just one stereo F5 is enough. But F5 (at least the "standard model" with one pair of IRFP devices) does sound a bit fat & flabby on the Acoustats. Or maybe I'm just not used to the interaction between them and the M3s playing the significant amount of bass which they usually don't with the more conventional A/B class amps. Anyway, the experiment might just as well happen to lead nowhere, but I have to give it a try.
@Tyu: My interfaces are (still) the standard MK121-2A (220uF bipolar cap, 6ohm varistor). This will soon change to "C", depending on how long it takes for 47uF caps to cross the ocean. The rest is available here.
In the meantime, I have never been disappointed or in any way let down by the standard interfaces; not in the tonality (except for the usual - low-mids taking a small step towards the back of the soundstage) nor in the efficiency - as a matter of fact, Acoustats are almost "twice louder" (perceptional, judging by the volume knob position) than the SoundLab 2A with bias pushed quite high.
@Bear: For my room ("L" shaped 32sqm, with speakers along the shorter 3.6m wall playing into the 6.5m long part of the "L") and my liking, even just one stereo F5 is enough. But F5 (at least the "standard model" with one pair of IRFP devices) does sound a bit fat & flabby on the Acoustats. Or maybe I'm just not used to the interaction between them and the M3s playing the significant amount of bass which they usually don't with the more conventional A/B class amps. Anyway, the experiment might just as well happen to lead nowhere, but I have to give it a try.
@Tyu: My interfaces are (still) the standard MK121-2A (220uF bipolar cap, 6ohm varistor). This will soon change to "C", depending on how long it takes for 47uF caps to cross the ocean. The rest is available here.
In the meantime, I have never been disappointed or in any way let down by the standard interfaces; not in the tonality (except for the usual - low-mids taking a small step towards the back of the soundstage) nor in the efficiency - as a matter of fact, Acoustats are almost "twice louder" (perceptional, judging by the volume knob position) than the SoundLab 2A with bias pushed quite high.
after living with all the mods for the 121...a,b,c what ever... the best sound out of the Acoustat panels...is with the No crossover 121a ...jim new this was the best ....as anyone would...the best crossover is no crossover...sound lab put a crossover in there interface...an look what even you have to say about the output...what like 3db diff in out put...you are right.... why would you then do the same with the acoustat 121 put a 47mf cap in the input...the a 220 junk cap is by-passet...but not the 47mf...
look i no this because i have done the works ....i am all for you doing the same....so dont think i am say not to go there....you wont no if you dont go...long live Acoustats....goodluck
look i no this because i have done the works ....i am all for you doing the same....so dont think i am say not to go there....you wont no if you dont go...long live Acoustats....goodluck
I hear you Tyu and thanks for that. I actually read (most of?) your threads on no-X-over subject and I generally agree with the concept - trafos are the xover already.
However... there's this worrying possibility of overloading the HF trafo, both sonically and electrically. So: I'll try all the options myself; listen and check for heat at my usual listening levels, and make a call. Now that I've split the interface (only one so far) and plan to re-wire using lugs wherever possible for the convenience if easy changes, nothing will be difficult from here.
However... there's this worrying possibility of overloading the HF trafo, both sonically and electrically. So: I'll try all the options myself; listen and check for heat at my usual listening levels, and make a call. Now that I've split the interface (only one so far) and plan to re-wire using lugs wherever possible for the convenience if easy changes, nothing will be difficult from here.
With the mods i have on my 121....my bias is off the HV mixer ....an bias can be set from 4-7k.....an yes i can drive 3ea 9"panels with a 50watt tube amp an get full output...
my room is 18'X25'X14'...best base i have ever got out of any ESl....the mods came from the guy with sound labs...thay came up with a way to setup the interface to get better output....i have setup my 121 this way....
As for the Acoustat high frc transfourmers only time i have over driven them with any amp ....without any crossover in front of the tranfourmer...was with low bias...bias is the key to all ESls....but you know this
goodluck
my room is 18'X25'X14'...best base i have ever got out of any ESl....the mods came from the guy with sound labs...thay came up with a way to setup the interface to get better output....i have setup my 121 this way....
As for the Acoustat high frc transfourmers only time i have over driven them with any amp ....without any crossover in front of the tranfourmer...was with low bias...bias is the key to all ESls....but you know this
goodluck
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