Anyone tried bi-amping?


(David Liguori) #21

There is a theoretical advantage in that each amp gets a narrower band of frequencies, hence, fewer possible intermodulation products. Whether we can actually hear that is another thing. But I’m all for tweaks as long as there is some valid theory behind them. Bi-wiring is another thing.


(Music and Shawarma Lover) #22

Well I was “bi curious” so I did the biamp thing and I think it sounds better. It is hard to say because A/B testing is pretty impossible with any reasonably quick switch. I had all the gear (Krell and Classe amps) but the active crossover anyway, and that I bought used for a really good price.


(Ged) #23

In the flat earth days of Linn and Naim, active bi and tri-amping was a big thing (and also a way of selling a shed load of amps.) My Exposure power amp came from the breakdown of a guy who had triamped active linn isobariks. Which did sound great.
I believe Slash from Guns N Roses had tri-amped Naim DBLs at one point according to the selling dealer. As an example of the kit racks needed.


In the days before mega powerful power amps it was also a way of getting a lot more power through the system.


(Music and Shawarma Lover) #24

I expect the lights would dim in my place if that was my stack! I probably have that many pieces, but it’s more of a used audio store kind of feel, not a bunch of matching stuff.

I will have to do more listening. Last night I took out the biamp array and put back in my Rogue Audio Magnum 120 tube monoblocks through the passive crossovers. My first thought was “this does not sound nearly as good.” But that would make biamping even more of a dramatic improvement than I thought…need more listening. It’s for science!


(Music and Shawarma Lover) #25

Here is a question for the engineers and electronics experts. I’d post it on Audiogon but that would inevitably lead to a debate about the desirability of biamping and probably about the right direction to install a fuse.

So here goes: could lack of use of a passive crossover network that is about 30 years old cause it to degrade faster than when it was in use? Like, could it basically “get cold and dry out” because I had it out of the loop for 8 months?

Here’s what happened: as above I’ve been biamping my Magnepans for about 8-9 months using a Marchand ACTIVE crossover between the preamp and the amps. Obviously then I bypassed the external crossover boxes that come with the Magnepans.

I decided to go back to a single amp and using the external crossover boxes for a comparison. The sound was shockingly different - darker, far less treble, no sparkle.

At first I thought to blame the amp I used. But I do not recall that when comparing any of the 3 amps I have had in rotation sounding that dramatically different than any other (Krell KAV 250A, Classe CA-200, Rogue Magnum 120 tube monoblocks) – noticeable, but not like this dramatic shift.

Then I had a thought that maybe it is just the passive crossover network being pretty old and not as “transparent” as it used to be. But I’d been using them for 7 years without feeling the speakers didn’t sound good, and while I recall the moment I first heard them biamped as being a noticeable upgrade, again, I don’t recall it being as dramatically different as my perception when I put the passive crossovers back in the path.

So, question would be - would lack of use of a crossover network potentially degrade it more than when it was used daily, like all the time every day? I wonder if letting them sit, versus using them all the time, accelerated something?


#26

I can’t answer the engineering question. But consider this: Biamping is likely better SQ than passive xover. You noticed some improvement when you eliminated the passive xover. You adapted to the new sound. Returning to passive xovers degraded the sound.

I notice a step down much more readily than a step up. The step up is subtle. The step down is like a gut punch. And when I get a step up, it becomes the new baseline and there is no going back.

Passive xovers are a signal suck. Active xover, well implemented, will be an improvement.

I had a similar experience even another notch towards less xover. I was running Omega SAMs (single driver, full range) and Rythmik powered 8" mid-bass woofers. I used a Marchand active xover to blend the two. All was good. After some time, I tried bypassing the Marchand, running the Omegas full range and blending the woofers using their plate amp controls. Sounded better to me. Went back to the Marchand after a few days and was surprised at how less alive things sounded. While the improvement was definitely nice, the degrading was intolerable. And I had lived with that level quite happily for some time.

Moral of the story: Active xover better than passive xover. No xover better than any xover! And… there’s no turning back!

I have to add, that improving the source with Auralic gear made these kinds of differences much clearer to me.

Now, a passive xover that is 30 years old might benefit with rebuilding and higher quality caps. If the original caps are electrolytic, then they definitely would! I rebuilt a pair of AR2ax speakers (for sale if anyone is interested) that were ~40 years old. I replaced the old electrolytic caps with decent quality, but not super boutique, Clarity Caps with the same specs. Noticeable improvement.

And, after all of that, you might consider trying HiFi Tuning fuses for some extra punch!! :wink: :clown_face:


(Music and Shawarma Lover) #27

Very interesting points, thanks. You may be right that the going down in quality is much more intolerable than the increase in quality was pleasant. Similar to how I hate to gamble because I don’t enjoy winning nearly as much as I hate losing.

And it may be that the only way to listen to the Magnepans is through biamping because the crossover boxes are aged, until I have them rebuilt (probably cost too much relative to the speakers’ resale value…they are worth more to me because I had the speakers rebuilt a few years back at substantial cost).

Does anyone know - what other speakers are as easy to biamp as Maggies? I mean, with external crossovers so that you don’t have to open the speaker cabinet to disconnect the passive crossover network? I find that I want to invest more in biamping gear (maybe a crossover upgrade; maybe a tube amp that isn’t a space heater like the Rogues) but if I do that, I would want that to be transferable to another set of speakers since I don’t see the Maggies lasting forever.


(Andrew Cox) #28

Hi James,

Any chance you could upload some screenshots of the crossover in question, particularly the capacitors ?

In general terms when looking for a culprit component in an aging circuit the smart money will be on “our friend the capacitor”. This paper describes the aging profile of electrolytic capacitors in various circumstances. Temperature plays an important role. The answer to your question about constant use and subsequent passive degrading might be found in the results relating to bias and square waves, but it didn’t leap out at me.


(Music and Shawarma Lover) #29

Thanks for that offer. Let me see how easy it is to disassemble an external crossover box to get a picture. With my luck, I would do something that requires a special tool or an Inspector Gadget hand to reassemble…

That is what I was thinking though, that the capacitors maybe aged due to lack of use. Then the question is whether it makes sense to have the crossovers recapped etc.

I waffle about what to invest in my Magnepan 3.3Rs. I love the way they sound, and with the biamping, sometimes I am really shocked at the quality of the sound.

But maybe the writing is on the wall - the speakers were manufactured in the early 90s and unlike a lot of cone and box speakers, it does not seem that Magnepans were built to last forever or be renewable.

Mainly I am talking about delamination. But I note that there seem to be almost no Magnepans earlier than 3.7 available - I don’t know if that is because they have all deteriorated and are in the dump, or if they’re so precious no one is selling their stash.