Bi-amping

[The Sandman]

I'm considering adding a second Aragon 4004 amp to my system.

Current setup:

Aragon 24K SP preamp > Bryston 10B Sub crossover [high pass] > Aragon 4004 Mk II amp > North Creek External Crossovers (biwired) > B&W 802 Matrix Series III speakers | Bryston 10B Sub [low pass] > JL Audio Fathom F112 subwoofer X 2 (stereo).

The preamp has two pairs of outputs. I'm thinking that the best way to add a second amp would be to horizontally bi-amp the 802s using the above cabling scheme for one amp, 10B Sub, 802 woofers, and F112s and the second set of preamp outputs for the tweeter/mid woofers and second amp. So the signal for the mids/highs would not be passed through the 10B Sub - only the lows would be.

Proposed bi-amped setup:

Amp 1:
Aragon 24K SP > Bryston 10B Sub [high pass] > Aragon 4004 #1 > North Creek External Crossovers > B&W 802 woofers | Bryston 10B Sub [low pass] > F112 X 2 (stereo).

Amp 2:
Aragon 24K SP > Aragon 4004 #2 > North Creek External Crossovers > B&W 802 mids/tweeters.

Is this the best setup for biamping my system? Are there any particular issues is using one set of preamp outputs with the Bryston 10B Sub and the other without (delay or phase issues for example)?

[jdandy]

Howard.......Here's how I would do it with the gear you have. Omit the external North Creek crossover. Feed the JL Audio f112 subs from the preamplifier's second set of stereo outputs. Feed the Bryston 10B Sub active crossover from the first set of preamp stereo outputs, then feed the 10B Sub low pass outputs to one Aragon 4004 to power the 802 woofers, and the 10B Sub highpass outputs to the other Aragon 4004 to power the 802 mids and tweeters.

[GaryProtein]

Originally Posted by jdandy

Howard.......Here's how I would do it with the gear you have. Omit the external North Creek crossover. Feed the JL Audio f112 subs from the preamplifier's second set of stereo outputs. Feed the Bryston 10B Sub active crossover from the first set of preamp stereo outputs, then feed the 10B Sub low pass outputs to one Aragon 4004 to power the 802 woofers, and the 10B Sub highpassoutputs to the other Aragon 4004 to power the 802 mids and tweeters.

I completely agree.

Mixing two brands of crossovers does not always yield good results (I have personal experience and expense with this) and you have simpler, shorter signal path this way.

[The Sandman]

Originally Posted by jdandy

Howard.......Here's how I would do it with the gear you have. Omit the external North Creek crossover. Feed the JL Audio f112 subs from the preamplifier's second set of stereo outputs. Feed the Bryston 10B Sub active crossover from the first set of preamp stereo outputs, then feed the 10B Sub low pass outputs to one Aragon 4004 to power the 802 woofers, and the 10B Sub highpass outputs to the other Aragon 4004 to power the 802 mids and tweeters.

Interesting idea, and something I could easily experiment with once I have the second amp. However, I'm not convinced that the 802s would benefit from active biamping versus the passive biamping I would be getting with the North Creeks. The North Creek crossovers are built to the same specs as the factory crossovers, except with much larger and higher quality components so that the sound is improved without changing the original character of the speaker. So basically, I could have asked the original question without mentioning the North Creeks at all, as if the speakers were using the factory crossovers. If I was going to try to actively biamp the 802s, I'd probably need to get something like the Pass XVR1 crossover, with a gazillion possible settings (accomplished with jumpers) in order to get optimum results.

As I've mentioned elsewhere, when I first got the F112s I added them to the system without the 10B Sub, running the 802s full range and setting the sub's built in low pass to high 30s Hz. Sounded pretty good, but when I added the 10B Sub (high pass 80 Hz to 802s, low pass 50 Hz to subs, all slopes 18dB/octave) the improvement was huge.

[chessman]

Originally Posted by The Sandman

As I've mentioned elsewhere, when I first got the F112s I added them to the system without the 10B Sub, running the 802s full range and setting the sub's built in low pass to high 30s Hz. Sounded pretty good, but when I added the 10B Sub (high pass 80 Hz to 802s, low pass 50 Hz to subs, all slopes 18dB/octave) the improvement was huge.

Howard, you just solved a mystery for me. I have been wrestling with whether a 10B Sub would really be needed since my preamp has two outputs and my subs have a low pass filter, but your experience seems compelling.

[The Sandman]

Originally Posted by chessman

Howard, you just solved a mystery for me. I have been wrestling with whether a 10B Sub would really be needed since my preamp has two outputs and my subs have a low pass filter, but your experience seems compelling.

I think so, although it seems to be a hard sell to many members here. It was the two Fathom reviews in Stereophile, JL Audio Fathom f113 powered subwoofer | Stereophile.com and JL Audio Fathom f212 powered subwoofer | Stereophile.com, that served as the model for my sub / external crossover setup.

[Whart]

I have a few additional thoughts, not to confuse things. One of the benefits of having a separate set of subs is to locate the bass speakers optimally in the room, independent of the mid-tweets. So, some measurements might be in order, along with a willingness to move speakers, listening position and furniture if you are going to go to all the trouble.
Second, I don't really know how the external crossover for the B&W you have works in relation to the internal one in the B&Ws- is the latter effectively eliminated from the signal path? You don't want a bunch of crossovers stacked up in the same signal path, right?
I gather you are concerned about the effect of the crossover in the JL on the mid-tweets? Does it have a high-pass output, so you would normally send the signal to the woofers first and let the woofer crossover separate the bass from the mid-highs, so your B&W's are not running full range? Or, are you planning to let the B & W's run full range, along with the woofers? This may make tuning the system even trickier in the room and eliminate one of the potential benefits of bi-amping, namely freeing up your full range speaker from the labor of producing the bass. It also makes figuring out the crossover frequencies trickier.
Two last thoughts: one, the notion of 'vertical' bi-amping, that is, not making one stereo amp carry the demand of a big bass tone in both channels simultaneously, which would occur with 'horizontal' biamping. Instead, that amp runs the bass speakers and mid range tweeters of one B&W, which may tax the power supply less, and make the amp run and sound better on demanding music.
Second, and again, i don't know your system, or the particular equipment well enough to comment, but would the system be improved by buying a better overall amp, rather than a second amp of the same type you currently have?
Final observation, consistent with Dan and Gary's comments- simple is better, fewer links, even passive in the chain.
FWIW, i have never had success mixing woofers with other speakers. I could certainly not do it with woofers and electrostats, and I still cannot do it with my AV horns, which use a dynamic woofer system. Granted, an all dynamic speaker system may be less difficult to integrate with a woofer system. But even in a simple system (and bi-amping and subwoofers on top of that ain't a simple system), getting the woofers to integrate with the rest is not, in my experience, easy on hi-fi (movie system stuff- way easier and less critical).
Sorry for the ramble. Hope it helps.

[The Sandman]

Originally Posted by Whart

I have a few additional thoughts, not to confuse things. One of the benefits of having a separate set of subs is to locate the bass speakers optimally in the room, independent of the mid-tweets. So, some measurements might be in order, along with a willingness to move speakers, listening position and furniture if you are going to go to all the trouble.

Second, I don't really know how the external crossover for the B&W you have works in relation to the internal one in the B&Ws- is the latter effectively eliminated from the signal path? You don't want a bunch of crossovers stacked up in the same signal path, right?

The external crossovers replace the factory 802 crossovers, which have been disconnected and removed from the speakers. You can find out more about the North Creek crossovers here: 801web, but basically they follow factory specs using much larger and higher quality components.

I gather you are concerned about the effect of the crossover in the JL on the mid-tweets? Does it have a high-pass output, so you would normally send the signal to the woofers first and let the woofer crossover separate the bass from the mid-highs, so your B&W's are not running full range? Or, are you planning to let the B & W's run full range, along with the woofers? This may make tuning the system even trickier in the room and eliminate one of the potential benefits of bi-amping, namely freeing up your full range speaker from the labor of producing the bass. It also makes figuring out the crossover frequencies trickier.

The Fathom subs do not have a high pass filter, and most members here run their main speakers full range and "add" the sub(s) for augmentation of the low bass with a low pass setting around 35 - 40 Hz. A few people (myself included) use an active external crossover like the Bryston 10B Sub to high pass to the mains and low pass to the subs. I find this latter setup much better in my system.

Two last thoughts: one, the notion of 'vertical' bi-amping, that is, not making one stereo amp carry the demand of a big bass tone in both channels simultaneously, which would occur with 'horizontal' biamping. Instead, that amp runs the bass speakers and mid range tweeters of one B&W, which may tax the power supply less, and make the amp run and sound better on demanding music.

My initial thought was to vertically biamp the 802s, but there are two issues - first, although my preamp has two sets of outputs if I send one set to each amp there will be no way (that I can see) to place the Bryston 10B Sub (active) crossover in such a way that it will high pass to the 802s and low pass to the subs.

Second, with horizontal biamping I will be able to get the active crossover out of the high/mid path, removing any loss of transparency the unit introduces (which is very little actually). Only the 802s woofers (and F112 subs) would receive signal via the active crossover (hence my question as to whether this will cause any phase or delay issues between the mid/high signal and the low signal).

Second, and again, i don't know your system, or the particular equipment well enough to comment, but would the system be improved by buying a better overall amp, rather than a second amp of the same type you currently have?

Certainly a reasonable question. We all have our system design philosophies, and at the moment mine is to see just how good I can make my system sound without upgrading to newer and/or more expensive equipment. A used Aragon 4004 Mk II costs less than $1000, and with some routine maintenence and some simple tweaks they still sound really good IMO. Using a pair will double my power into the 802s but more importantly, it will double my Class A power into the 802s. The 4004s put out 200 wpc into 8 ohms, 400 wpc in 4 ohms, and for the most part the 802s are around 4 ohm speakers. So it's quite a bit of power. Eventually I'm sure I'll upgrade the whole system to something outrageous (which AA members apparantly consider the norm ).

[Whart]

Here's the part that I'm now focusing on now:

"My initial thought was to vertically biamp the 802s, but there are two issues - first, although my preamp has two sets of outputs if I send one set to each amp there will be no way (that I can see) to place the Bryston 10B Sub (active) crossover in such a way that it will high pass to the 802s and low pass to the subs.

Second, with horizontal biamping I will be able to get the active crossover out of the high/mid path, removing any loss of transparency the unit introduces (which is very little actually). Only the 802s woofers (and F112 subs) would receive signal via the active crossover (hence my question as to whether this will cause any phase or delay issues between the mid/high signal and the low signal)."

First, and maybe I'm missing something here (not being facetious, maybe I am), but if you have two sets of stereo ouputs from the preamp, what does it matter whether the (stereo) amps are stacked horizontially or vertically in relation to the B&W's, for the purpose of inserting the active Xover into the signal path? Arent they, for these purposes, like four mono amps?
And second, (coinciding with your second point), if you are running an active crossover to high pass to the B & W, how is that getting the active Xover out of the high/mid signal path?

Best,
bill hart

[The Sandman]

Originally Posted by Whart

Here's the part that I'm now focusing on now:

"My initial thought was to vertically biamp the 802s, but there are two issues - first, although my preamp has two sets of outputs if I send one set to each amp there will be no way (that I can see) to place the Bryston 10B Sub (active) crossover in such a way that it will high pass to the 802s and low pass to the subs.

Second, with horizontal biamping I will be able to get the active crossover out of the high/mid path, removing any loss of transparency the unit introduces (which is very little actually). Only the 802s woofers (and F112 subs) would receive signal via the active crossover (hence my question as to whether this will cause any phase or delay issues between the mid/high signal and the low signal)."

First, and maybe I'm missing something here (not being facetious, maybe I am), but if you have two sets of stereo ouputs from the preamp, what does it matter whether the (stereo) amps are stacked horizontially or vertically in relation to the B&W's, for the purpose of inserting the active Xover into the signal path? Arent they, for these purposes, like four mono amps?
And second, (coinciding with your second point), if you are running an active crossover to high pass to the B & W, how is that getting the active Xover out of the high/mid signal path?

Best,
bill hart

Answering your second question first, if I was to horizontally biamp the 802s, one amp would power the woofers in both speakers and the other amp would power mids/tweets in both speakers. One pair of preamp outputs would go to the active crossover, with the high pass then going to the 802 woofers and the low pass going to the subs. The other pair of preamp outputs would go directly to the mid/tweeter amplifier, thus "avoiding" the active crossover.

As to the first question - the preamp does indeed have two stereo pairs of outputs. One pair goes to the active crossover, which in turn outputs one stereo high pass pair and one stereo low pass pair. The low pass pair goes to the subs. That leaves one high pass pair from the active crossover and one full range pair from the preamp. This mismatch is what makes vertical biamping difficult in ths setup. The mids/tweets can accept a full range signal - the passive crossover will take care of everthing. But the passive crossover won't limit the low bass to the woofers - that's the active crossover's job. It's complicated - I didn't figure it out myself until I drew it out on paper.

BTW, if we used 4 mono amps instead, it would in effect be horizontal biamping, not vertical, because the two amps driving the woofers would theortically see a different load than the two amps driving the mids/tweets, whereas if we vertically biamped with 2 stereo amps, each amp would see the same load.