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Bi amping speakers

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faustus

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Post Sat Oct 20, 2007 9:31 pm

Forgot to mention one other biamplification item that I discussed with Rolland Barr: vertical biamplification using Carver amps.

Per Rolland, there will be no damage to the amplifier from running one channel with low freq signal and the other channel with high freq. However, the sonic results will probably be displeasing due to the power sharing between the channels... the low freq channel will hog almost all of the power and the high freq channel will get starved.

Also, per Rolland, this power sharing characteristic is the reason that Carver amps generate more than double rated power when used in a mono role -- the single channel doesn't have to share power with the second channel any longer = way more efficient.
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bob p

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Post Sat Oct 20, 2007 9:40 pm

faustus wrote:this power sharing characteristic is the reason that Carver amps generate more than double rated power when used in a mono role -- the single channel doesn't have to share power with the second channel any longer = way more efficient.

that's commonly known as push-pull amplifier design. nothing magic about it.
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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faustus

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Post Sun Oct 21, 2007 12:15 am

Metalbent,

Did you get a reply from Boston about biamping your VR3 speakers?
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jvandyke_texas

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Post Sun Oct 21, 2007 12:51 am

Just started reading this thread.
I have not seen anyone mention amplifer-speaker damping factor.
A passive crossover's job is to decouple out of band signals from amp to speaker driver.
At -3dB crossover frequency, the crossover has an impedance equal to the speaker (depending on phase.)
Any out of band speaker resonance will cause the speaker cone to flab around without the amp's iron fist damping to control it.
I also just noticed this on the ESP site. Look at block diagram.

If I were bi-amping, I'd remove the inductor between amp and woofer (and cap if 2nd order.)
This should provide tighter control to upper bass.
Other passive elements to midrange and tweeters are harder to remove for obvious reasons.

Early in his career, Carver constructed an amp-speaker closed loop system where the woofer had a sensor that fed back its position to the amp.
Using negative feedback, the amp would ensure the woofer position followed the music, not the electrical signal out of the amp.

Other topic, in normal crossovers, second order LC filters such as those to tweeters do cause amp load shorts at series resonance.
Phase Linear 4000 Series I,II, 700B Series I,II, Carver C-4000 champagne, black, C-4000t, TX-11a, AR-XB, Pioneer PL-512, Speakerlab K
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bob p

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Post Sun Oct 21, 2007 3:00 am

what a coincidence. we had some questions about servo subs in one of the other threads only a few hours ago!

WRT active biamping and retention of the passive crossovers, IMO this should only be done during one's initial tests to see if one wants to follow through and go all the way with active biamping. if that's the case, my preference is to gut the xovers from the cabs if you can get away with it, retaining only notch filters if you absolutely have to have them. passive crossovers don't do anything to help performance, and they do everything to hurt it.

ymmv.
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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BillD

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Post Sun Oct 21, 2007 10:07 am

My understanding of bi-wiring, and what is said in both my Sunfire amp and AL-III guides is separating the high and low frequency legs (remove jumper) and using the SAME amp to drive the different legs (so the amp gets the entire spectrum). Indeed, the Sunfire, with its current and voltage outputs for each channel says you should bi-wire ribbons using both legs, with the current source to the ribbon, and the voltage source to the woofer. There is no crossover in this application, and no separate amps.

BTW, the phase relationship might not just be 0° and 180° degrees. It could also be 90° (not likely) and 270° (3rd order). This, my friends, is what I believe is the phase relationship of the woofer system, and no amount of switching polarity is gonna fix that.

So, if you're gonna disable the passive crossover, do it entirely! Now, there's the nonlinearity of both the ribbon and the woofer to contend with, which the passive crossover smoothed out. You're gonna need some equalization there!
It should sound like it isn't there!
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Making life enjoyable through expensive electronics.
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Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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Mr. M-500t

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Post Sun Oct 21, 2007 10:24 am

Thank's you guys for all of your input and opinions. I guess we'll find out in a week or so what happens. It's just a matter of waiting for my stuff to arrive.
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bob p

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Post Sun Oct 21, 2007 3:44 pm

again, my understanding of bi-wiring is just like bill's. but so many people have used the term in different ways since it originated that now it has become ambiguous.

Bill, WRT phase shifts, the textbooks say that when you use a 3rd order / 18 dB/octave filter, you MUST change the polarity of the tweeter on a two way system, or the midrange on a multi-way system, while keeping the other drivers in phase with the woofer. I appreciate that 270 is not an integer multiple of 180, but there's a reason for watching limb polarity for the second driver from the bottom. its discussed in some of those tech papers at the rane site.

good speaker designers that use 3rd order passives that impart a 270 degree phase shift will design their cabinets with the phase changes in mind to correct for the lobing artifacts that will be caused by the crossover. rane has some good tech papers on this in their online library. one other thing to consider when switching to an active crossover is whether or not is a good idea to switch to an active crossover that has a slope that is different from the slope that your speakers/box were designed for. the driver alignments may not be optimized for different slopes.
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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Mr. M-500t

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Post Sun Oct 21, 2007 9:33 pm

BillD wrote:My understanding of bi-wiring, and what is said in both my Sunfire amp and AL-III guides is separating the high and low frequency legs (remove jumper) and using the SAME amp to drive the different legs (so the amp gets the entire spectrum). Indeed, the Sunfire, with its current and voltage outputs for each channel says you should bi-wire ribbons using both legs, with the current source to the ribbon, and the voltage source to the woofer. There is no crossover in this application, and no separate amps.

BTW, the phase relationship might not just be 0° and 180° degrees. It could also be 90° (not likely) and 270° (3rd order). This, my friends, is what I believe is the phase relationship of the woofer system, and no amount of switching polarity is gonna fix that.

So, if you're gonna disable the passive crossover, do it entirely! Now, there's the nonlinearity of both the ribbon and the woofer to contend with, which the passive crossover smoothed out. You're gonna need some equalization there!


Now look what you did Bill ! ](*,)
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bob p

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Post Sun Oct 21, 2007 10:34 pm

one down, one to go.
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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Mr. M-500t

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Post Sun Oct 21, 2007 10:38 pm

bob p wrote:one down, one to go.


bob p, I'm impressed. That has to be the shortest post you've ever made ! :p :p :p
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bob p

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Post Sun Oct 21, 2007 10:47 pm

not! ;)
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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Mr. M-500t

(pair of) SILVER-7 TUBE AMPs

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Post Sun Oct 21, 2007 10:55 pm

bob p wrote:not! ;)


OK, That was ! =D>
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bob p

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Post Sun Oct 21, 2007 11:23 pm

:D
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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TNRabbit

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Post Mon Oct 22, 2007 1:31 am

Now THAT was!!

BTW,I'm learning a LOT in this thread; keep it up, guys!
TNRabbit
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