Question on bi-amping TSW-910 speakers....

[VintageChris]

First off does anyone by chance know where i can possible find a downloadable copy of a owners manual for these speakers? i was not able to find one in the library.

These are not mine they belong to a good buddy of mine, we are kicking around what way will be the best to power these, to pick up one larger amp to power them or to biamp, one option being a vertical split using one amp for the top end one amp for the bottom end, or to do a horizontal split using two matching amps bridged one for each speaker.

The single amp and the bridged horizontal bi-amp are pretty strait foreward and i have had experience with both these approaches, its the verical bi-amp that he is leaning towards that has us scratching our heads, first off without an owners manual he does not know what the power rating and ohm rating is for the top end and the bottom is on these when you vertical bi-amp these, does it stay four ohms and what is the wattage rating for the top and bottom individually when bi-amping this way ? any sugestions how much wattage he should be looking to put to the top end verses the bottom end? the speakers are rated at four hundred watts max, should he say do two 2 hundred watt amps or should he use a higher wattage amp for the bottom end and a lower wattage amp for the top end?

He is holding off buying the amps and a pre amp till we can find out the specs we need to know so we can put proper power to these, if he does decide to vertical bi-amp he is planning on using a pre amp with a high low split feature, any and all sugestions as to the best way to amp these will be appreciated.

Thanks Chris

.

[ar_pro]

My experience is with vertically biamping the original AR-9, and I've found the absolute best arrangement to be a pair of identical stereo amplifiers.

Many power amplifiers lack level controls, and matching sensitivities between dissimilar amplifiers can be a chore.

If you feel like experimenting, it's unlikely that you could do any harm by trying different amps, but if you want the most straightforward, hassle-free method, just buy a pair of identical 200 watt/channel stereo amplifiers, and use one with one speaker, and the second with the other.

A speaker's split internal bi-amp crossover obviates the need for an external "high-low" capability in a preamp - each signal should be full-range to the speaker's jacks, and let the crossover do its thing.

[VintageChris]

Thanks thats what i was thinking as well going with a horizontal bi-amp using two matching amps bridged, but i can see the appeal to vertical bi-amping as it leaves you with the option of using say a tube channel amp to power the top end and a solid state for the bottom end, but having never done this type of setup i would like to hear opinions of this type of bi-amp to see if it is worth pursuing.

[rrcrain]

My own experience with biamping is it delivers little to nothing if done passively, It may sound different, but that's not necessarily better.

[ar_pro]

My own experience with biamping is it delivers little to nothing if done passively, It may sound different, but that's not necessarily better.

Referring specifically to the AR-9, and assuming excellent amplification and properly-restored speakers to start, the improvement is subtle; but the vertical bi-amp configuration affords the best result I've ever heard from this speaker.

And although the AR-9 (like virtually all of AR's classic systems) has the reputation of being extremely inefficient, the upper-range drivers exhibit a remarkable ability to project a less-than-quiet amplifier's noise components into the listening space.

Vintage Dyna amplifiers seem to be a particularly poor choice for driving the upper half of the AR-9 crossover, as their hum & hiss at idle more than cancels out any perceived tube-related benefit.

I've also heard CJ and McIntosh tube amps on the upper section, and while they are by nature, quieter than Dyna, their higher cost is not offset by any performance benefit.

Again, the best result seems to come from identical, robust & reliable solid-state amplifiers - Mac, Crown, the older big Adcom amps - something that can supply a solid 200 (or more) watts/channel all day long.

[rrcrain]

Ar_Pro,

I'm using a pair of Heathkit AA-1800's in a biamp configuration with a Marchand XM26 crossover in front of them. The crossover points are set at 100Hz for the high pass and 400 Hz for the low pass. (One octave over and under the speakers crossover point) Using the active crossover, there's a very noticable improvement in clarity of the vocals and the bass is cleaner, better defined to the point it sounds as if the speakers reproduce lower frequencies than they actually are.

My opinion. Passive biamping...eh, not that great.

Biamping with a decent crossover configured correctly, very very good.

This particular amp is dead quiet (my opinion) and 2 ohm stable per a retired Heeathkit engineer I traded emails with a few years ago.

[xmas111]

I have my AR9's vertically biamped using two Carver TFM-45's.....they put out ~ 500 watts per channel at 4 Ω. That's a 1000 watts per speaker! Of course I never play them loud enough to use all that power but they do sound fantastic.

John

[VintageChris]

Thanks guys for the passing on your experiences, allot of good insight and things to think about, i mentioned to Greg ( my buddy with the 910s) that he should become a member on here and get involved in this discusion as altimately its going to be his decision which way to go, but this is admittredly something i as well would like to learn more about.

Sorry for my inexperience but could someone clarify for me the passive verses active crossover, is the passive approach basically bi-amping just using the stock speaker crossovers and the active aproach using an external crossover, if this is right do you eleiminate the speakers internal crossovers or just use a active crossover in conjunction with the speakers internal crossover, sorry if this is a dumb question, i have been using amps for years but just not in a bi-amp configuration so this is all new to me.

This does interest me personally though as I do own a pair of AR 90s that eventually i would like to upgrade the crossovers in, and i am considering possibly modding them to be bi-ampable like the 9s are.

John wow thats allot of power, i bet it sounds wonderfull ! you and my buddy Greg would get along just fine, the 910s for him are a recent acquasition, he also owns a pair of AR9s as well, inherited from his late father, they are being powered with some monster mckintosh amps with similar power to what you feeding yours, if i can get him to become a member on here i will let him talk about that setup.

Ar_Pro,

I'm using a pair of Heathkit AA-1800's in a biamp configuration with a Marchand XM26 crossover in front of them. The crossover points are set at 100Hz for the high pass and 400 Hz for the low pass. (One octave over and under the speakers crossover point) Using the active crossover, there's a very noticable improvement in clarity of the vocals and the bass is cleaner, better defined to the point it sounds as if the speakers reproduce lower frequencies than they actually are.

My opinion. Passive biamping...eh, not that great.

Biamping with a decent crossover configured correctly, very very good.

This particular amp is dead quiet (my opinion) and 2 ohm stable per a retired Heeathkit engineer I traded emails with a few years ago.

This sounds like a good way to go as well, thanks for the insite

[ar_pro]

Ar_Pro,

I'm using a pair of Heathkit AA-1800's in a biamp configuration with a Marchand XM26 crossover in front of them. The crossover points are set at 100Hz for the high pass and 400 Hz for the low pass. (One octave over and under the speakers crossover point) Using the active crossover, there's a very noticable improvement in clarity of the vocals and the bass is cleaner, better defined to the point it sounds as if the speakers reproduce lower frequencies than they actually are.

My opinion. Passive biamping...eh, not that great.

Biamping with a decent crossover configured correctly, very very good.

This particular amp is dead quiet (my opinion) and 2 ohm stable per a retired Heeathkit engineer I traded emails with a few years ago.

Sounds interesting - have you bypassed the internal crossovers, or are you still using them along with your external Marchand electronic crossover?

[VintageChris]

Sounds interesting - have you bypassed the internal crossovers, or are you still using them along with your external Marchand electronic crossover?

same thing i am wondering.....

[rrcrain]

^{Using the original crossovers. The marchand crossover points are an octave over and under the speakers crossover point. I'm guessing the improved clarity is a result of a lower Im distortion, but that's jsut a guess. These amps supposedly have an incredibly low THD and IM as it is.}

[Steve F]

I'm a little confused.....If you are using an external crossover for your amplifiers at 100Hz LP and 400Hz HP, then regardless of whether or not the speaker's internal x-o is in play, the speaker itself is not being fed a full-range, continuous signal. There is a gap in the input signal going to the speaker (between 100 and 400, the magnitude of which depends on the respective slopes of the filters), but some discontinuity, right? I fear the perceived increase in clarity may just be a hole in the overall system in-room response, reaching a maximum between 200-300Hz. This is the frequency region where there are a lot of clarity-robbing room resonances and the like, so an electrical 'suckout' in that region may, in fact, be beneficial in your room.

But if you are LP/HP'ing the signal at 100/400 before the signal even reaches the speakers, you are likely introducing a droop in the system's response in that frequency region--which, as I said, may be beneficial and add to the perceived "clarity" of the overall sound.

Steve F.

[rrcrain]

Your looking at the crossover points backwards. 100hz. and up go to the high end. 400 hz and down go to the bass. There's a 300 hz overlap.

[Steve F]

I'm relieved. I didn't think you would do as I described.

(Yesterday was a tough day for me!)

[rrcrain]

I have seasonal allergies and this spring is a nightmare. I know all about hard days that last for a couple of months.

[tysontom]

rrcrain,

Are you saying that on your AR9s that you are bypassing the built-in passive crossover in favor of an electronic crossover? I guess I'm not following you on this either. What you have basically described is a passive bi-amp configuration, but I'm not sure how you have connected your speakers. Could you explain further?

Definition in the bass actually comes from the overtones—not the fundamentals of deep bass, so the woofers themselves don't possess the ability to have "better definition." There is no practical way to change the characteristics of the damping of the two 12-inch woofers without changing the "Q," and you can't do that with any increase in damping factor or other amplifier change. The "Q" of the two woofers is actually slightly over-damped at 0.5, so you wouldn't want to change this even if you could.

"I'm using a pair of Heathkit AA-1800's in a biamp configuration with a Marchand XM26 crossover in front of them. The crossover points are set at 100Hz for the high pass and 400 Hz for the low pass. (One octave over and under the speakers crossover point) Using the active crossover, there's a very noticable improvement in clarity of the vocals and the bass is cleaner, better defined to the point it sounds as if the speakers reproduce lower frequencies than they actually are."

--Tom Tyson

[rrcrain]

Sigh. The curse of the written word can be confusion.

Tom,

No, the speaker crossover is intact, in place, and unmodified except the original caps were replaced years ago.

A bit of uninteresting history might help.

Around 10 years ago, I only owned one amp, an AA-1800. Due to the power company, it died, or perhaps a better word would be it was killed. It was sent out for repair and after being gone for no less than 2 months, I decided to scrounge eBay for a replacement amp. I found another AA-1800 with problems for a decent price and had it sent to the same shop with the intention it be scavenged for parts to repair the first amp. What I received back was two fully functioning amplifiers and a robust repair bill.

Now, what to do with to big, heavy amps.

Experimentation and curiosity took over. I tried the inexpensive, simple passive biamping approach. The sound was "different" but not better. For whatever reason, it sounded out of phase, that's the best I can describe it.

I then tried using a Heathkit Pro series crossover. The "out of phase" issue was gone but the crossover points couldn't be set correctly for these speakers and it left a hole in the sound. This was "on loan" from a local store at no cost.

I then tried another crossover (can't remember the name). Again, it solved the "out of phase" sound caused by passive biamping, but left a hole.(Resold it back on ebay, no money lost)

I bit the bullet and ordered the Marchand crossover as a kit (saved myself around $1,000). This crossover can be configured as a butterworth, Linkwitz Reiley or notch filter. Literally any set of crossover points can be specified and be changed quickly later if so desired.

I knew I had a winner the day I caught my wife singing along to a song she previously complained about; She couldn't understand the lyrics. With the crossover in place, she could understand the lyrics perfectly.

So, I suppose my point is I didn't jump into biamping for the sake of biamping. I more or less stumbled into it by accident and experimentation.

[Steve F]

I'm still unclear as to how this is "bi-amping" if the speaker's passive crossover is downstream from the input signal. Whether you are feeding the woofer section a full-range signal or whether you are feeding it a 400 Hz-and-below signal, the AR's passive internal crossover is still taking the input signal and passively LP'ing it at 200 Hz. The internal crossover is "throwing away" any input to it above 200Hz. The speaker doesn't know whether the "unused" signal only extends to 400 Hz or whether it goes all the way out to 20kHz.

Same thing is happening on the HF section.

The only true biamping would occur if the AR's internal x-o were bypassed completely, and an external crossover was used--an external x-o with crossover points and slopes appropriate for the speakers drivers' characteristics.

Then--and only then--would bi-amping's real advantages (the upper-order bass distortion harmonics wouldn't be reproduced by the HF amp, and neither would there be deleterious IM interaction between the two amps) be apparent. And that assumes that the HF and LF sections are correctly level-matched so the speaker's original design spectral balance is not disturbed, and, as I said, that the external x-o's slopes, phase, and frequency points are correct for the drivers.

I suspect that the advantages you're getting are the result of double the amplifier power, and therefore you're never running into even the slightest amplifier-induced distortion. Because if the speaker's internal passive x-o is in the signal path after the input signal, it's not bi-amping at all.

Steve F.

[rrcrain]

The active crossover is in front of the amplifiers. Each amplifier only reproduces what the crossover sends it.

As for distortion. I've never heard either amp distort. Rated THD is .025 up to 250 watts.

[Steve F]

"The active crossover is in front of the amplifiers. Each amplifier only reproduces what the crossover sends it."

Correct. I understand that perfectly. Doesn't matter to what I'm saying one bit.

My point is that whether or not the LF amp is sending your AR a 400Hz LP'd signal or a full-range signal, it doesn't matter: The AR's internal passive x-o is still doing its thing, taking the signal fed it it, and 'extracting' 200 Hz and below and sending it to the woofers. It's the AR's passive x-o that's feeding the woofers, not your amp directly. LP'd at 400 Hz or full-range, it doesn't matter. That consideration is completely invisible to your speaker.

You're not bi-amping.

If the amps reproduced what the crossover sent it and then fed the speakers directly--no internal passive x-o in the way "downstream"--then you'd be bi-amping. But the external x-o would have to have the correct characteristics or the end result might be worse than before.

But if your speaker's internal passive crossover is in the signal path right before the drivers, then regardless of what takes place before the passive crossover, you're not bi-amping your speakers.

Steve F.

[ar_pro]

If the AR-9's internal crossover was completely bypassed, you'd then need FOUR channels of properly-processed amplification for each speaker, no?

In other words, the AR-9 cannot be "bi-amped" without using the internal X/O.

Without the internal X/O, it could be "quad-amped", with a 4-channel electronic crossover, and a pair of stereo (or 4 mono) amplifiers, per loudspeaker.

I'm not sure what could have caused the internally-biamped system to sound "out of phase" - I've never encountered the issue, and suspect it has something to do with the Heath amplifiers. That said, I don't know why they would then sound OK, with an electronic crossover, unless phase adjustments were in play.

[Steve F]

How do you figure it would need four channels per AR-9 speaker? I suppose that's true if you were powering each driver independently, since it's a four-way speaker. You'd need an external x-o (after the pre-amp but before the power amps) with the 200, 1200 and 7000 Hz x-o points, all properly sloped and phased, feeding 4 channels of amplification, then feeding each driver independently, with the levels of each of the 4 channels of amplification properly set.

For conventional "bi-amping," I'm figuring no internal passive woofer-to-LMR x-o (go inside and disconnect it), but retaining the LMR-to-UMR-to-tweeter passive x-o's. Feed the LF section directly with a properly low-passed amp, then feed the entire LMR/UMR/HF section directly with an amp HP'd at 200Hz (but keep the LMR-to-UMR passive at 1200Hz in place, and the UMR-to-HF passive 7kHz in place). This utilizes the two sets of binding posts that are there.

In any event, both your way and my way assumes no internal passive 200Hz x-o inside the speaker cabinet being operational in the signal path. Otherwise, it's not bi-amping.

Steve F.

[rrcrain]

Steve,

Your splitting threads and politely as possible, you are in part, incorrect.

>>But the external x-o would have to have the correct characteristics or the end result might be worse than before.

This statement is dead on. Absolutely no arguement.

Read the letter on this link.

http://www.classicspeakerpages.net/library/acoustic_research/ar-9_series_1978-1981/ar-9_series_other/letter_from_george_at_ar_re/

[ar_pro]

Right - you could "bi-amp" the speaker (2 channels of amplification, and a 2-channel electronic crossover to feed the upper & lower sections), but you would still need to use the upper portion of the 9's built-in crossover.

A true active-electronic crossover for the AR-9 would require a 4-way EC and 4 channels of amplification, per speaker.

Based upon AR's letter regarding the question of bi-amping the AR-90, it would seem that without the passive crossover components, the drivers could not give the desired (designed) result.

[rrcrain]

Steve,

The bass section of the crossover is required for proper phase alignment, it can't be eliminated and as you've correctly pointed out per the letter I referenced, the upper section can't be removed unless your willing to quad amp the speakers. My pockets aren't that deep.

Technically, what I have is a "hybrid" biamping.

This comes back full (or at least a half circle" to the begining. "Most" passive bass filters are less than efficient at filtering out higher frequencies. Generally, only an active crossover can do this function well. (Lots of general statements there.) In the case of the AR9/90 bass crossover, this is the case. As an experiment, I did only connect the bass section with a full signal and was rather surprised to hear Shaina Twain coming out of the bass drivers. Not clearly and not all that loud, but the vocals were intelligable if only barely. With the active crossover, there's less "garbage" for the bass crossover to block/reject or filter out.