So in a typical two way the tweeter impedance will go to infinity in the bass, and the opposite in the woofer. The impedance will rise to infinity in the treble.
Of course, that "infinity" may be at 1 Hz and 1 MHz, so in the actual audible range you'll never hit it, but 30-100 Ohms maximums are not impossible.
If you want to play with this, using a crossover simulator like XSim and designing a very basic crossover will help you see what is going on.
Beside the advantage of a bi-amped speaker presenting an impedance of less variation to each of the two power amps than one amp sees from a non-bi-amped speaker, the speaker’s drivers are also connected directly to the amps, not to the speaker’s internal crossover components. Bi-amping is usually (and best) done with an external electronic x/o before the two amps.
Beside the advantage of a bi-amped speaker presenting an impedance of less variation to each of the two power amps than one amp sees from a non-bi-amped speaker
Sorry @BDP24 this is not really true as you put it. See from my blog post and any simulation, the min to max impedance is MUCH greater with a split crossover.
The overall current load however is always decreased. This may help the power supplies stiffen up.
While active bi-amping is good, it’s also complicated. It’s much easier to get top of the line parts and design in a passive. Do what you like, but it’s no free lunch. It is however preferred in pro environments as the dynamic range and amplifier to output is improved. Need less total watts for the same SPL.
The impedance curve of the speaker is separated into two pieces: high and low. The amplifiers only get one of those respective load curves. With most bi-amp-able speakers, the low cutoff feeding the midrange and tweeter is still in the circuit. Likewise, the high-cutoff still rolls off the highs hitting the woofer. Put both together as one load to one amplifier, and additional interactions affect sound quality, usually for the worse. Bi-amping worked very well for my system, but ymmv.
I have bi amped several systems and never heard a difference that would justify the additional amp. Bi wire, same thing. I did hear a difference with an active 3 way system with an external crossover though. It was a Linn isobarik Brik system. I also copied the the Linn system with 3 Bryston LP2's and a Behringer 3 way analogue crossover. It was awsome. And cool to talk about. :)
I have bi amped several systems and never heard a difference that would justify the additional amp. Bi wire, same thing. I did hear a difference with an active 3 way system with an external crossover though. It was a Linn isobarik Brik system. I also copied the the Linn system with 3 Bryston LP2's and a Behringer 3 way analogue crossover. It was awsome. And cool to talk about. :)
Kudos for going the extra mile.I have been promoting multiamping here for years. I designed the Beveridge RM3 crossover which allows easy changes and has level controls for both outputs. It is all discrete analog.
Most here haven't the nerve to so what we have done so they just bad mouth what we are doing. They dont understand the advantage of removing the un-wanted signal Before the amplifier rather than after. They would rather waste their money on expensive crossover components for a less than optimum solution.
Someting to think about. If the bass voltage is still present in the treble amplifier then the IM it creates is going to be the same.
Beside the advantage of a bi-amped speaker presenting an impedance of less variation to each of the two power amps than one amp sees from a non-bi-amped speaker
@erik_squires says
Sorry @BDP24 this is not really true as you put it. See from my blog post and any simulation, the min to max impedance is MUCH greater with a split crossover.
The overall current load however is always decreased. This may help the power supplies stiffen up.
While active bi-amping is good, it’s also complicated. It’s much easier to get top of the line parts and design in a passive.
Sorry, erik. BDP24 is correct. Individual drivers have rather smooth impedance curves because they are mass loaded drivers and thats what mass loaded drivers do.. The wild impedance variations we see in complete speakers are due entirely to the passive crossover which we want to eliminate.
The complication is not a large one and the benefit is enormous. Any serious audiophile needs to give it a try and we are here to help at www.berkeleyhifischool.com
Yes for speakers with complex impedance dips and peaks there can be a significant change when you biamp. We dont care about the peaks, its the dips that bother the amplifier. Drivers themselves do not dip below their DC resistance. However when combined with inductors and capacitors this is no longer true (unless its 1st order).
When you separate the high and low crossovers (unstrap them) the impedance of each will improve because it no longer sees the other.
Sorry, erik. BDP24 is correct. Individual drivers have rather smooth impedance curves because they are mass loaded drivers and thats what mass loaded drivers do.. The wild impedance variations we see in complete speakers are due entirely to the passive crossover which we want to eliminate.
You’d be correct if we were talking about active bi-amping AND removing existing filter sections which I did not believe we were.
WIth passive bi-amping we remove only the connection between the two filter sections while leaving the filters in place. In that context I was not incorrect.
I apologize if this wasn't clear from the blog posts I pointed to.
Being able to get rid of the speaker-level crossover parts is one of the two reasons for bi-amping (doing so has at least the potential for producing a worthwhile improvement in the sound quality of a loudspeaker). The other is, as Roger Modjeski said above, to separate the low frequencies from the mids/highs in the amplification (giving each it’s own amp, of course), thereby decreasing the potential for the creation of IM distortion in the amp(s).
Bi-amping need not be complicated and difficult. And, it can be cheaper than replacing stock speaker-level x/o parts with those pricey boutique ones. Not only that, you can use a brute-force amp on the woofers if you want, with a nice tube amp for the mids and highs. I first bi-amped with a pair of Magneplanar Tympani T-I loudspeakers in 1973, using the ARC passive x/o designed specifically for that task. Nelson Pass makes a great electronic x/o, but it’s not cheap. Fortunately he also makes (or made, it has just been discontinued) a modestly-priced 2-way x/o, the First Watt B4. It provides 1st/2nd/3rd/and 4th order filters in 25Hz increments from 25Hz to 3200Hz. All discrete (no opamps, no ic’s), retail price $1500. Reno Hi-Fi may have one left, I don’t know. For DIY’ers, it will soon be available as a kit.
Bi-amping need not be complicated and difficult. And, it can be cheaper than replacing stock speaker-level x/o parts with those pricey boutique ones.
Really the only one’s who should engage in this are those who have speakers specifically designed with active crossover in mind (pro speakers), or who can build their own speakers anyway.
Everyone else is probably going to do it wrong and is far better off with a single amp solution.
bdp24 said..
Beside the advantage of a bi-amped speaker presenting an impedance of less variation to each of the two power amps than one amp sees from a non-bi-amped speaker
This is what I think he is saying.
The advantage of a bi-amped speaker is that is presents an impedance of less variation to the individual power amps than what one amplifier has to deal with when the high and low drivers are strapped together.
I think this is easy to confirm. Just think of capacitors and inductors hooked together vs them not.
I dont see why you say this statement is not true. Seems true to me. I believe bdp is saying that the high and low terminals driven together are a much more difficult load than the high and low terminals strapped together.
Really the only one’s who should engage in this are those who have speakers specifically designed with active crossover in mind (pro speakers), or who can build their own speakers anyway.
Everyone else is probably going to do it wrong and is far better off with a single amp solution
.
Well they have my permission and I am willing to help. Ye of little faith.
Is it soooooooo hard to buy a woofer and a tweeter, divide the signal before the amps, choose appropriate amps.
As far as I am concerned, speaker level crossovers where an ok solution when one had only one amplifier. Now we have lots of ampifiers. A 6,12,18 db/octave analog crossover is childs play.
Being able to get rid of the speaker-level crossover parts is one of the two reasons for bi-amping (doing so has at least the potential for producing a worthwhile improvement in the sound quality of a loudspeaker). The other is, as Roger Modjeski said above, to separate the low frequencies from the mids/highs in the amplification (giving each it’s own amp, of course), thereby decreasing the potential for the creation of IM distortion in the amp(s).
Bi-amping need not be complicated and difficult. And, it can be cheaper than replacing stock speaker-level x/o parts with those pricey boutique ones. Not only that, you can use a brute-force amp on the woofers if you want, with a nice tube amp for the mids and highs. I first bi-amped with a pair of Magneplanar Tympani T-I loudspeakers in 1973, using the ARC passive x/o designed specifically for that task. Nelson Pass makes a great electronic x/o, but it’s not cheap. Fortunately he also makes (or made, it has just been discontinued) a modestly-priced 2-way x/o, the First Watt B4. It provides 1st/2nd/3rd/and 4th order filters in 25Hz increments from 25Hz to 3200Hz. All discrete (no opamps, no ic’s), retail price $1500. Reno Hi-Fi may have one left, I don’t know. For DIY’ers, it will soon be available as a kit
.
Thank you bdp. I am in total agreement. We may have to do some education on this. There are many crossovers out there. My Beveridge RM-3 shows up now and then for a few hundred dollars.
I have recently made some 2nd and 4th order Linkwitz-Riley PC boards that use a quad op amp. I will supply a TL-074 but any quad opamp will work.
Hi, Ive been reading your blog. Do you really feel this way about stereophile. Hearing aids? Trick? What is the "stereophile curve "?
For a long time I've had trouble matching up Stereophile reviews with my experience of the same speakers. I think I've found the reason why. They aren't reviewing speakers at all. They are reviewing hearing aids pretending to be speakers. This is why they are so expensive. What I mean is that the speakers Stereophile praises would only sound good to some one with hearing loss between 7kHz and 15 kHz, which I lack. It's clear that completely different manufacturers have taken advantage of this "trick."
I'm calling this trick the "Stereophile Curve" and the more I go back in time to look at megabucks speakers rated highly, the more apparent the truth of this curve becomes. Of course, the alternate, benign explanation is that the reviewers have all bought the B&W studio heritage hype, and they have become accustomed to thinking of the B&W 800 series speakers as a neutral reference, which, objectively, they can't be.
IMO, parametric equalizer pair with active crossover can make a huge improvement!
I like the crossover of course. Many audiophiles will shy away from the EQ. I see no need in adding anything digital either.
One can easily select a crossover point simply from the response curves now available for all drivers. I still go to Madisound first. They appear to have everything with good documentation.
If people want to start discussing how to select drivers I'm up for it. We might even have a serious conversation and get something done.
HiFi was once and experimenter's hobby. I hope to bring some of that back.
The most interesting loudspeaker product I am aware of is Roger’s new Music Reference ESL loudspeaker/dedicated direct-drive OTL amplifier combination (a great idea, though audiophiles don’t like to have their amp dictated to them ;-). ESL transparency, speed, lack of coloration (unsurpassed vocal and instrumental timbre, texture, etc.), and all the other ESL attributes (okay, I love ESL’s!), and no input (step up) transformer. And driven by a dedicated, direct-drive OTL amp (no output transformer, the tubes connected right to the ESL panels). What could be more pure?! A powered sub is included, and since not a single other power amp or other electronic component is required or necessary, you just feed the system the signal of your choice. The combined price is less than that of the multi-driver/complex-crossover monstrosities reviewed in Stereophile every month. I’m saving up for my pair ;-) .
There are companies making powered monitor loudspeakers for the pro sector (Westlake Audio, for one), but if you have heard any of them you know they aren’t exactly audiophile products, made for listening to music in the home. Sensitive and dynamic yes, but too colored, shouty, and coarse for me.
My Integrated amp rated at 250/8-425/4 shut down driving my power hungry speakers that have 2 pair of binding posts on back they’re 4 way 6 ohm rated and manufacturer recommends 500 watts. My question for the experts assuming I can get the amps output levels matched is, Would my integrated be less likely to overheat at the same spl if I added a 2nd amp, removing the strap to horizontally bi amp the speakers? also if I got output levels matched would amps of identical power be necessary or could I wire a pair of 350 mono's to the bass of each speaker and use the int to drive the top end?
Would my integrated be less likely to overheat at the same spl if I added a 2nd amp, removing the strap to horizontally bi amp the speakers?
Yes. Passive bi-amping would limit the current for the bass to only one of the two amps, therefore reducing the actual power drawn during the same musical performance as before.
also if I got output levels matched would amps of identical power be necessary
No
or could I wire a pair of 350 mono’s to the bass of each speaker and use the int to drive the top end?
Sure. An added advantage of this method is the ability to add EQ to the bass section alone, often a good improvement.
If you are going to go with active crossovers, you seriously should just make your own speaker. DIY your own speaker pair is something I think every audiophile should do at least once.
Build it from the ground up and learn what you need to do along the way, instead of this half baked approach.
For the record, almost all passive crossovers also include some form of EQ. If you plan to remove and replace a passive crossover you need to be prepared to do both. And now I leave you guys to hack and play around.
My Integrated amp rated at 250/8-425/4 shut down driving my power hungry speakers that have 2 pair of binding posts on back they’re 4 way 6 ohm rated and manufacturer recommends 500 watts. My question for the experts assuming I can get the amps output levels matched is, Would my integrated be less likely to overheat at the same spl if I added a 2nd amp, removing the strap to horizontally bi amp the speakers? also if I got output levels matched would amps of identical power be necessary or could I wire a pair of 350 mono's to the bass of each speaker and use the int to drive the top end?
Sometimes getting technical gets to the answer far better than a stack of nontechnical thought.
When I tried to run my ESLs off a high quality integrated I learned a lot. For instance the rated power is only deliverable into a resistive load. Anything reactive shut the amp down and a message came up "check for shorted speaker wires" That speaks volumes. The amp thinks anything below X ohms is a short.
After reading the manual carefully I found that we could selectd 4 or 8 ohms but that did not affect the output power at all, only where the protection cut in. Selecting 4 was worse than 8 and shut downn sooner. This is not the behavior of a good solid amplifier.
Integrateds are not rough and ready power amps in general. 250/425 watts is power amp land and I mean big power amp land. How much does your amp weigh? Would you care to tell us its model? Sounds like a simple case of amplifier does not like speaker. A second amp will help indeed. Let the current integrated take the lighter load.
Have you found an impedace curve for the speaker. Usually you can just google its name + impedance curve using images.
So the bottom line is that there seems to be something to be said for light loading.
It was rather obvious to me from the start. The tubes love it.
Does anyone have any questions about why it works so well? The distortion reduction is usually 5 to 1 or more and the damping (regulation) doubles. Noise goes down 3 dB. All you give up is imaginary headroom.
When I tried to run my ESLs off a high quality integrated I
learned a lot. For instance the rated power is only deliverable into a
resistive load. Anything reactive shut the amp down and a message came
up "check for shorted speaker wires" That speaks volumes. The amp
thinks anything below X ohms is a short.
Yep. ESL's are basically giant capacitors. 1/3 of an ohm at the top of the spectrum is not unheard of. Fortunately there's very little music power at 20kHz, but it is not an easy load in general.
Thanks for the interest. My Int is A Hegel H360 and the speakers are Revel salon2's. Though I chose the unit to go with the salon1's I had at the time i'm happy with the synergy with the new speakers and now i've had the Hegel just over a year and the new speakers since march I did manage to trip the thermal protection once. I know heat kills and I horizontally bi-amped my R105/3's successfully in the past. The 2nd amp made a big difference with the kef r105/3 speakers really filling out the bottom end.
The current .7 series Maggies have series crossovers, and are therefore not candidates for bi-amping. The .6 and earlier have parallel crossovers, and can be bi-amped. An electronic x/o is used in place of the external one supplied by Magnepan with the 3.6, and the speaker benefits greatly from bi-amping. Not just for the benefits mentioned above (eliminating the possibility of amplifier IM distortion, etc.), but because instead of one, brute-force amp on all the speaker’s drivers (Maggies need lots of current), two smaller, perhaps better-sounding amps can be used. A ss on the bass panels, a tube on the mid/tweeter is a favorite combination, one I myself employ with my Tympani T-IVa’s. Some long-term Maggie user/owners have therefore chosen to stay with the older models (the .6 is a favorite), primarily to be able to bi-amp.
For the record, almost all passive crossovers also include some form of EQ. If you plan to remove and replace a passive crossover you need to be prepared to do both.
A local speaker builder brought over a pair of his speakers without crossover for me to play with bi amping. The drivers are a $225 Scanspeak woofer and $60 Tweeter. $225 woofers only show up in $10,000 speakers. Most of the price of a complete speaker is in the cabinet and margin for the dealer. When an interested party took at a $10,000 speaker, priced out the components and found the drivers plus crossover to be about $1,000 or less. Its just the economics of the speaker business.
The drivers my local guy had chosen had such flat response that no EQ is needed nor does he build any into his series crossover. The impedance was amazingly constant and he feels this is the main virtue of his speaker. If a speaker has a flat impedance curve then damping is not so big an issue. Good drivers have pretty flat response, that is what you are paying for.
I have never found a need to add EQ to a bi-amp system if the drivers are good quaity. Besides, in a bi-amp system you already have a woofer and tweeter control (you need only one) to adjust the tonal balance which I do at my own pleasure. The knob is right next to the volume control which I also adjust for my own pleasure. Its all so simple, but so hard to get across. I have to climb the wall of marketing just to get someone's ear.
There are companies offering DIY loudpseaker kits, the drivers and speaker-level passive x/o parts, along with required enclosure (or OB baffle) specs, provided. You make the enclosure (or buy one with the specified internal volume; Parts Express sells good ones) or OB baffle, and install the drivers and x/o. One such is Danny Richie at GR Research, located in Texas. He is a renown x/o designer, doing work for other speaker makers. Very high performance-to-cost-ratio speakers. Danny specializes in high-sensitivity designs (and is a fan of OB's) for use with low-power tube amps. Details on the GR Research website.
Like its predecessor, the H360 boasts a whopping 250Wpc into 8 ohms, or 420Wpc into 4 ohms. Its damping factor is over 4000 -- four times that of the H300. It should have no difficulty driving just about any pair of speakers it’s hooked up to.
I see he is impressed with daming factors that are very large and 4 times larger is, 4 times better?. We know 1000 or 4000 makes no difference.
If you trip the thermal something has to be done. Can you now put your hand on the heatsinks after extended playing? If not you are still too hot.
The h360 has been in my system over a year now and only shut down the one time. I owned a pair of kef R105/3's for over 20 years and they had 93.5 db eff so compared to the salon2 at 86 db they played considerably louder with less power. I read the review and every other I could find after hearing the h360 at home and being so impressed with it, I had never heard of the company and needed to know more. When it shut down it was only warm to the touch and I really probably shouldn't be chasing the ear bleeding levels those old kef's could reach anyhow. When the music is coming out so clean it's easy to get in trouble with the volume control.
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