Bi-amping...should you?

steveinaz · December 2003

**keep in mind the following is my opinion, I'm just tryin' to save you some money**

Speaking in reference to 2-channel only systems:

Many new folks ask about bi-amping and wether or not it is worth it. The answer is no, wait, ...yes, umm...it depends.

I've done the bi-amp route myself for a number of years, so I'll interject my experiences with it. I had 2 identical 200watt/rms amps; one powering L/R woofers, one powering L/R mid/highs.

The first question to ask yourself is how much money are you willing to spend? Secondly, if you bi-amp, will you be compromising because of cost related issues. If the latter is true, I think you and your music will be best served by NOT bi-amping.

Bi-amping with "compromise" equipment is like putting Walmart tires on a Corvette. The subtle improvement that bi-amping brings is sometimes difficult to discern on the finest of equipment. Bi-amping should only be done if 1) You have the money to do it right. 2) The performance increase will justify the cost involved. Now, as I've told many here, if you've got the bucks to bi-amp properly (meaning you are not compromising because of cost), by all means go for it! Your system will never sound "worse" by bi-amping, but the question is..is it worth the money?

I submit to you, that it is not; in all but about 2% of circumstances. If you're a typical "working stiff" you are far better served with one very good quality amplifier, than you are by buying 2 compromise amps for the sake of bi-amping. Ask any of the experienced folk's on this board, and I'll bet next month's pay they'll agree with that statement.

Bottom line: Think about it long and hard before bi-amping, believe me when I say the improvement is subtle if at all apparent. Build your "base" system first, with no compromises; then decide for yourself if purchasing a second amp will significantly increase your systems performance/quality. You want a big upgrade? Take that $800 you're about to pluck down on that second amp and upgrade your TT or CD Player--now there's a noticable improvement that won't leave you disappointed....

Click my link below, it is the simplest best sounding system I've ever owned; no bi-wiring, no bi-amping, just very good basic equipment and top-quality cables. No compromises. It "sings"

madmax · December 2003

I would add that if you are not willing to spend the money to bi-amp then bi-wiring will get you most of the way there, depending on the speakers and amplifier combination.
madmax

Tour2ma · December 2003

Bi-amping can be an economical way to improve an under powered system. Underpowered is not necessarily the same as quality compromised in my book.

steveinaz · December 2003

Are you talking "bi-amping" or simply adding an amp for additional power? 2 different things....I agree that adding an external amp to a receiver can be a economic way to increase power---no argument there. What I'm addressing above is bi-amping for the purpose of higher resolution, 1 amp driving low frequencies, 1 amp driving high frequencies.

steveinaz · December 2003

Originally posted by madmax
I would add that if you are not willing to spend the money to bi-amp then bi-wiring will get you most of the way there, depending on the speakers and amplifier combination.
madmax

Absolutely! Good point. But here again, as long as you don't scrimp on your speaker cables for economical purposes--you're better off with 1 very good quality set of cables, then bi-wiring with 2 sets of cheap cables.

Tour2ma · December 2003

Originally posted by steveinaz
Are you talking "bi-amping" or simply adding an amp for additional power? 2 different things....I agree that adding an external amp to a receiver can be a economic way to increase power---no argument there. What I'm addressing above is bi-amping for the purpose of higher resolution, 1 amp driving low frequencies, 1 amp driving high frequencies.

Bi-amping.

steveinaz · December 2003

Ok, then I would say that if someone is going that route, then they compromised on their receiver from the start, either for economical reasons, or they just didn't know enough about audio at the time of purchase. I would recommend that they keep the money they were going to invest in the add-on amp, sell the receiver, and use all of the money to purchase the receiver/integrated/seperate to get the power they need.

Why drop a Corvette engine in a Neon? Buy a Corvette.

Keep in mind this is my opinion only, and you know what they say about opinions....

George Grand · December 2003

There are also loudspeakers that have very demanding woofer sections. These in my opinion are definite candidates for bi-amping. The demands that the four, 12" woofers aboard my AR-9's place on an amp, don't leave much for the lower mids, upper mids, and tweets. They drop down to 2.9 ohms in areas. I bi-amp for that reason.

George Grand (of the Jersey Grands)

steveinaz · December 2003

George, do you have the old AR-9Lsi? Big tower with the downward facing woofer, circa 1984'ish?

George Grand · December 2003

Steve,

No, I have the 1978-79 vintage AR-9. Big tower with two side firing 12" woofs per speaker. Woofers are on opposite sides of the cabinets. AR kind of cheaped out with the Lsi.

I hate to be repetitive about this, but not very long ago, on a different website Ken Kantor, the chief designer and founder of NHT had this to say about the original AR-9:

"Those speakers set the standard for low end performance when they were introduced, and to this day."

Mr. Kantor knows a thing or two about building loudspeakers. I think he was responsible for the mid 80's AR MGC-1's ("Magic" 1's), and definitely was chief designer for the AR-303, which was the 40th anniversary re-make of the AR-3a. I met him at Grand Central Station in October 1994, which was the site of the gala affair celebrating the 40th anniversary of Acoustic Research. Cool guy. Super smart too! Sad to say there will probably NOT be a 50th anniversary party. Not enough of a company left to celebrate. I could cry over that.

A souvenier of that event, and a prized possession, is a copy of Villchur's book, "The Reproduction of Sound" signed by both Edgar Villchur AND Henry Kloss. Another piece that goes into the earth with me at the end of my ride.

George Grand (of the Jersey Grands)

steveinaz · December 2003

I had the AR9Lsi in 1983 and I adored those things. I still miss them. Got'em at the audio/photo club for $900/pr, at the time they retailed in the states for like $1,400.00.

They were great speakers...

George Grand · December 2003

The old audio/photo club. Rhein-Mein? What did you do with them?

Only freakin' speakers you can buy at the exchange now are Blose. Is that a kick in the pants or what?

First speakers I ever bought at the BX were a pair of RTA 11t's, for $290/pair in 1988 or 89. Yes, they made a pricing mistake. No, I didn't tell them. Didn't stop the BX from selling me a second pair a few days later, for $272. On both occasions I waited for the hand on my shoulder as I walked towards the exit. You gotta love it.

George Grand (of the Jersey Grands)

organ · December 2003

Great post Steve! I agree with you completely. But one advantage I see with bi-amping is the ability to control the highs and lows. If you have two amps where one performs very well with bass and the other is bass shy but has great mids, bi amping might be a good idea.

I'm more confused about bridging than bi-amping. I know you get more power by bridging, but the impedance is cut by half. In bridge mode, the amp will see an 8 Ohms speaker as 4 Ohms. So the extra power doesn't mean much.

Maurice

organ · December 2003

Double post, sorry.

Tour2ma · January 2004

Maurice,
I don't see why the impedance drops in bridging an amp. The speaker is not changing???
Will be curious to see added posts on this.

GG,
Good point on the speaker demands. We've seen many 150 owners who have been forced to bi-amp due to the demands.

steve,
As I see it your premise is "know what you're doing and be able to afford what you need to do". In that case folks would enter the wonderful world of audio in their 40's... Where's the fun in that?

George Grand · January 2004

Tour,

I concur with Maurice. I have seen this statement in a lot of different places, to include the owners manual for the Carver power amps that I DO use in bridged mode (M4.0t, TFM-42). Bridging halves the impedance that the speakers are rated at.

George Grand (of the Jersey Grands)

steveinaz · January 2004

True. This is why amp manufacturers insist on 8ohm speakers if you're gonna bridge the amp.

Organ:

As far as quoted power outputs in bridged mode--they should be stated @ 8 ohms. So there is a significant power increase.

madmax · January 2004

Originally posted by steveinaz
Absolutely! Good point. But here again, as long as you don't scrimp on your speaker cables for economical purposes--you're better off with 1 very good quality set of cables, then bi-wiring with 2 sets of cheap cables.

Not to argue the point but I'm really not sure that two cheap conductors might not be better (with some speakers) than one really good cable. Really, just not sure. I'm thinking of those LSi15's I had. The bass section really seemed to be messing with the treble through my type 4 audioquest cable and the problem was solved with some runs of cheap RCA brand wires. I bet it depends on how power hungry the bass section is.

madmax

steveinaz · January 2004

It would certainly depend on the cables in question. For a long time I had bi-wired/bi-amped sets of 10awg Monster Cable terminated with very good quality gold bananas (when I had my Pinnacle speakers); Replacing this bi-wire set with a single run of Audioquest Granite made me a believer, real fast. I haven't bi-wired/bi-amped since--which led to me buying my Athena's (they're not bi-wirable), and a single, better quality amplifier.

I've never looked backed, I love the simplicity and pure sound I get...

Manamp · January 2004

Sorry I did not go through the entire thread but am replying to Steveinaz's initial post.

IMHO, Bi-amping is the exact opposite of a compromise as far as sound is concerned. (you could call it a compromise because it hits your wallet but not because of the sonic benefits attained by it.)

Bi-wiring is not even in the same league as Bi-amping (well maybe they both start-off with "bi" but then a whole lotta words being with "bi" and I am not going there.)

Amplifiers have strengths and weaknesses and assuming any given amplifer has both, to me buying that single amplifer is a compromise (opposite of Bi-amping).

You can categorize amplifiers in many ways but to simplify and explain my position, I will use 2 categories of amplifiers.

1) Those with high global negative feedback (also usually synonymous with high damping factors and low distortion) and

2) Those with low negative feedback (a.k.a. Rich harmonic content, creamy mids, soft sound even tubelike and gobs of distortion.)

The two have their own advantages, the high NFB types will give you tight rock solid and clean bass but may be too analytical even harsh in the mids and highs. On the flip side the low NFB types often have lush mids, soft highs but flabby/loose bass.

So which one will you choose? Well if you ask me, I choose BOTH. and the way to make it work is bi-amping. I will put the high NFB amp on the woofers and the Low NFB amp on the mids and highs and I get the best of both worlds. Did anyone say compromise? Nope, I say the best of both worlds.

I do agree with Steve that is does make the set-up costly but here is where half the joy of Stereophilia lies, experimentation. With the advent of eBay there are few excuses.

A word of caution if you mismatch the amps and not use their strengths, you could actually end up with a system that sounds worse than a single amp, so knowing what amp to use in which bandwidth is important.

It is well known that amplifiers like to be driven in limited bandwidths, one of the reasons is that higher frequencies ride on top of lower frequencies thereby halving the effective voltage drive any amp can provide before clipping for example:

If you have a 50 watt amp, it provides 20 volts into an 8 ohm load.

If you have a 10kHz wave riding on top of a 100Hz sinewave, the amplifier will begin to clip with both frequencies driven 10 volts (10+10=20) and as we know 10 volts into 8 ohms is 12.5 watts.

So in effect your 50 watt amp will begin to clip at 12.5 watts for each individual frequency where one is riding on top of the other. The only time you will get the full 50 watts is on maybe a drum solo or something similar.

Now back to Bi-amping, you have a 100 watt (28.28volts) amplifier driving your bass and a 50 watt (20 volts) amp driving your highs, thats equivalent to having a single 291 watt amplifier (not 150watt) why you ask? because 28.28 + 20 =48.28 volts and the power formula works like this 48.28 squared divided by 8 (ohms) equals 291watts.

So basically your humble 100 and 50 watt amplifiers will play as clean as a 291 watt amplifier assuming you have complex music signals (which is the case 97% of the time).

There are several other benefits of bi-amping that would take a white paper to present.

Needless to say Bi-amping is an excellent technical solution to many of the problems people face whislt running their amps at medium (or higher) levels..... but the real reason for doing it is that you get the tight punchy bass and lush mids both at the same time (and not have to spend $$$ getting a Krell).

For the budget minded, I highly recommend using a Kenwood M2 power amp ($250 on ebay) on the Bass. (220 wpc with 1000 damping factor) and an Adcom GFA-545Mk.II (also about $250 on ebay) on the highs. (100wpc and very detailed and natural mids/ highs).

Using the above formula, this $500 combo will sound clean, tight and natural like few amplifiers can and will sound (when needed) as loud as a single 615 watt per channel amp!! beat that for $500.

You can go on from there.

In my set-up, currently powering my B&W matrix 801's, I have a Nakamichi PA-7 powering the highs (low NFB design) and an upgraded Adcom GFA-555Mk.II (high NFB/ high DF) powering the bass. I love it this way.

There are many other variables to consider i.e. the cost of an Active crossover if you want etc but in a nutshell, Bi-amping done well can blow your mid away. Its the best of both worlds.

PS: My system is actually tri-amped. I have 2 Kenwood M2's running bridged feeding a pair of JBL 15" subs.:cool:exact opposite of a compromise

Manamp · January 2004

Tour2ma,

The logic of halving impedance is more to do with the amplifier's perception of load than your speakers changing impedance.

In a bridged set-up, each channel provides twice the current to make up those "extra watts" and hence twice the current looks to the amp like half the impedance.

From the amp's perspective half a load means twice the current the amplifier has to provide. How that load becomes half? We will see below.

It is no coincidence that the bridged out put of amplifiers is almost always twice of the their 4 ohm output. i.e. an amplifier with 200 into 8 ohms and 325 into 4 ohms (Adcom GFA-555) will make twice of 325 or 650 watts into a single channel. (I know Adcom rates it at 600 watts but it actually does 650.)

Mathematically speaking, driving a 4 ohm load using a single channel @ 325 watts translates roughly into 36 volts and 9 amperes. When the amplifier is bridged, it is required to make 72 volts at 9 amps (650 watts into a single 8 ohm load). Since each channel is running out of phase, the voltage is added while the current drive remains constant. If you look at the numbers, (36+36=72) the bridged drive into 8 ohms is exactly twice that of each channel running independent 4 ohm loads.

Hence to the amplifier running a 4 ohm load requires 9 amps and so does running both channels bridged into 8 ohm, each channel still needs to output 9 amperes. So the load on each channel is the equivalent of a 4 ohms load.

Hope this helps,

Arif.

steveinaz · January 2004

Originally posted by Manamp
Sorry I did not go through the entire thread but am replying to Steveinaz's initial post.

IMHO, Bi-amping is the exact opposite of a compromise as far as sound is concerned. (you could call it a compromise because it hits your wallet but not because of the sonic benefits attained by it.) [/B]

My statement was that bi-amping with compromise equipment, is a compromise. By "compromise" I mean that you're settling on cheaper amps for the sake of bi-amping--I see it here on this forum all the time--it is a waste of time. As an example, you will have better quality music with 1 Parasound HCA-1500A, than you will with 2 HCA-1000A's, bi-amp'd. How do I know? I asked Parasound. Because the output transistors of the HCA-1500 are a step-up from the HCA-1000, ultimately your sound is better. And according to Parasound "..will far exceed any benefit you might get by bi-amping with the HCA-1000A.."

Keep in mind that Parasound stood to make more money off me by selling 2 HCA-1000's.

Originally posted by Manamp
Bi-wiring is not even in the same league as Bi-amping (well maybe they both start-off with "bi" but then a whole lotta words being with "bi" and I am not going there.)
[/B]

I disagree. Although I DO believe bi-amping (properly) sounds better, it's a very subtle difference from bi-wiring (assuming the bi-wiring is done properly).

As I stated earlier, do what you want--it's your dime. I just trying to save you some money and disappointment. I've been doing this for 31 years, and have tried many different set-ups; I'm just relaying the results I've experienced...

Tour2ma · January 2004

Originally posted by Manamp
If you have a 10kHz wave riding on top of a 100Hz sinewave, the amplifier will begin to clip with both frequencies driven 10 volts (10+10=20) and as we know 10 volts into 8 ohms is 12.5 watts.

Still chewing on this... but until I figure it out, I'll damn well avoid any classical music at any volume level...

Originally posted by Manamp
Now back to Bi-amping, you have a 100 watt (28.28volts) amplifier driving your bass and a 50 watt (20 volts) amp driving your highs, thats equivalent to having a single 291 watt amplifier (not 150watt) why you ask? because 28.28 + 20 =48.28 volts and the power formula works like this 48.28 squared divided by 8 (ohms) equals 291watts.

So basically your humble 100 and 50 watt amplifiers will play as clean as a 291 watt amplifier assuming you have complex music signals (which is the case 97% of the time).

Excepting of course that each section of your 8-ohm speaker (with jumpers in place) presents a 16-ohm load when the jumpers are removed for bi-amping. Changes the math a bit.... yes?

As for the apparent load on a bridged amp, your explanation makes sense... Thanks, but one more question, whence does your use of "whilst" come?

Steve,
Should be obvious by now that you cannot save us from ourselves. No matter how hard you try, some of us are just going to think for ourselves and ultimately disagree.

steveinaz · January 2004

I'm fine with disagreement...it can lead to a learning something new, but I did want to correct Manamp on the way he was interpreting what I stated.

This thread was intended for the beginner/novice, so that they realize that alot of these "techniques" are quite expensive, and can be disappointing if you're an average listener, or have average hearing for that matter.

My belief is that "you can't polish a ****" and I've seen alot of novices; to use an anology: Put the $6000 stereo in the $1,500 Kia. My point is, be patient; walk before you run. Build a good basic system first--then experiment with bi-amping, bi-wiring, etc...

Manamp · January 2004

Steve,

I mean no disrespect but Bi-amping is a totally different animal than Bi-wiring. The only thing they have in common is the fact that the speaker is getting the signal from 2 sets of wires than one. The difference is more pronounced if you have active crossovers prior to amplification and connect the amp directly to the drivers (woofer) as opposed to connecting them via power wasting Inductors.

You may have been doing this for 31 years and I believe you have but I have been working with Amplifier designs for over 15 years in more of a technical capacity. Playing around with actual topological tuning, effect of various passive components in the circuit, the effects of using various active devices in the same circuit etc. I subscribe to a forum where we have discussions with Mr. Pass and actually John Curl himself (Parasound chief designer et all).

There is no such thing as "quality" of output devices or "step-up" as the Parasound guy calls it. And anyone who uses the term (be it from a customer service rep or technical rep at Parasound) loosly is not sure of what they are talking about. (My apologies if I come on as arrogant, I don't mean to be

). I just get irritated when pseudo marketing types try and slip one fast one by us.

Output devices can be rated on several parameters and these parameters may be bad or good for the same device depending on the application and desgn. A simple example is outputs with high gain are thought to be good. However use them in an output triple configuration and they will be highly unstable.

Another example is trying to use a high wattage and very robust device (a.k.a. good quality as far as reliability is concerned) in a low current application and while it will work, it will be too sluggish to have a decent slew rate or even sound good for that matter.

I looked at the specs of the two transistors that they use in the HCA-1000A and 1500A, they are pretty much identical except that one goes to 60Mhz and the 1000A's device is rated at 50Mhz. That means practically nothing. It is but marketing hype.

Technically the speed of the devices affect the frequency response (maybe distortion) and slew rates. As you can see those numbers are identical for both models.

Also to have a perfectly fine running amp, you don't need a device that capable of higher than 5Mhz. Infact all the Adcoms used the 5Mhz device and so did Krell till a few years ago till they had custom made devices. Even those top out at 35Mhz so the claim of this Parasound rep that going from 50Mhz to 60Mhz will make a sonic difference when all measureable parameters between the two amps are the same (not to mention the Amp is NOT capable to operate above 0.1Mhz ) is nothing I find credible.

With that out of the way, I agree with your statement that garbage in, garbage out but still there will be a noticeable sonic improvement purey because the amps have to deal with less bandwidth each vs one dealing with both.

By the way when you conducted your bi-amp tests, did you use an active crossover before the power amps or just used 2 amps and let the passive crossovers in the speakers do their work?

The latter is nearly as bad as not Bi-amping at all... I see little benefits of doing so. The real benefit is having an active crossover before the power amps and also eliminating the bass driver's crossover and connect the amp directly.

As I said bi-amping not done right is better off not doing. (maybe this is what you mean as well).

My 2 cents.

Manamp · January 2004

Originally posted by Tour2ma
Still chewing on this... but until I figure it out, I'll damn well avoid any classical music at any volume level...

Excepting of course that each section of your 8-ohm speaker (with jumpers in place) presents a 16-ohm load when the jumpers are removed for bi-amping. Changes the math a bit.... yes?

Not exactly, jumpers in or out, your load will still be 8 ohms because you have a crossover in place. Without the crossover, your analogy might have been A-ok. (Actually it will be 4 ohms and removing the jumpers make it 8 ohms each assuming 8 ohm nominal drivers)

However because the crossover is in place, (lets assume asimple 2 way crossover crossed at 2kHz first order running at 6db per octave) the impedence of the tweeter will begin to increase at 6db/ octave till it reaches near infinity at DC or low frequencies.

On the flip side the impedance of the woofer will do the same albeit with increasing frequency. Hence across the spectrum both will still remain at 8 ohm in their respective crossed over frequencies. Over all for the amplifier, it will not see a load lower than 8 ohms because the drivers operate in their respective regions.

There are always exceptions and caveats but lets not go there.:D

Hope this helps,

Arif

steveinaz · January 2004

Yes, I'm aware of the differences between bi-amping and bi-wiring. Yes, I know the difference between active and passive crossovers. My setup was passively/vertically bi-amped. I no longer bi-wire or bi-amp.

If you need to doctor your system to this degree, it might be time to reconsider what you purchased; or to simply spend the money to have a live jazz band play in your living room nightly, to attain the ultimate fidelity.

Yes, if you had read my entire post you would have seen the quote:

"Bi-amping should only be done if 1) You have the money to do it right. 2) The performance increase will justify the cost involved. Now, as I've told many here, if you've got the bucks to bi-amp properly (meaning you are not compromising because of cost), by all means go for it! Your system will never sound "worse" by bi-amping, but the question is..is it worth the money?"

Sheesh...now is there something in the above quote that you disagree with? See the very first line of the thread...

Manamp · January 2004

Its cool Steve, I respect your views and in my opinion, to answer your question, it is definitley worth doing. :cool:

izafar · January 2004

Originally posted by Manamp
Not exactly, jumpers in or out, your load will still be 8 ohms because you have a crossover in place. Without the crossover, your analogy might have been A-ok. (Actually it will be 4 ohms and removing the jumpers make it 8 ohms each assuming 8 ohm nominal drivers)

However because the crossover is in place, (lets assume asimple 2 way crossover crossed at 2kHz first order running at 6db per octave) the impedence of the tweeter will begin to increase at 6db/ octave till it reaches near infinity at DC or low frequencies.

On the flip side the impedance of the woofer will do the same albeit with increasing frequency. Hence across the spectrum both will still remain at 8 ohm in their respective crossed over frequencies. Over all for the amplifier, it will not see a load lower than 8 ohms because the drivers operate in their respective regions.

There are always exceptions and caveats but lets not go there.:D

Hope this helps,

Arif

Wow, This is the first time some one explained clearly why an 8 Ohm speaker will still have 8 Ohm impedance on both set of binding posts after removing jumpers.

I am running an external 5-Chanel amp with my reciever. Several times the idea of biamping crossed my mind. I would do it by using both reciever's amp for upper end and the external amp for bottom end. Though most of you guys will not like this idea (specaily based upon my humble equipment), I am very intrigued to see how it will sound.

Manamp · January 2004

Izafar,

Provided you do it right with an electronic crossover, I am confident you will see an improvement. The biggest will be in bass, you will able to get more clean sound without strain.

Good luck!

PS: Don't worry about the humble equipment you have, it will still pay-off if done right.

izafar · January 2004

OK, I tried that and am already back to original configuration. I was not expecting it to sound this bad.

I didnt use an electronic crossover as I dont have any. I have stacking banana plugs at the amp end therfore just moved one set to the reciever's outputs.

The resulting sound had very lifeless high end. There was plenty of high freq response, but of very differnat nature, e.g more of hiss then actual instrument sound. My wife described it as radio like sound.

I dont know if it is due to very bad amp section in Denon or difference in gain of the two amps, any how I am back on square one and am pretty happy with it. I would try this in future with two identical good quality amps (when ever I will get my hands on a pair).

Bi-amping...should you?

Comments