What's the biggest advantage to bi-amplify your Infinity?

[Zarathustra]

The more expensive Infinity's all have provisions to bi-amplify them with or without a dedicated control unit.
As far as I know the QLS, Q2, Kappa 8 & 9 don't have such a CU but the rest starting in time with the QRS have one. The most expensive ones with apart cabinets for the low-end like the RS-1 and IRS (has a 2 kW amp iside its basscolumn) must be biamped.
My question is this:
- Apart from the benefit of using two stereo amps, four mono amps or a combination of those and having generally speaking more power to "play' with, what's the most beneficiary thing to use the bi-amp provision for the Infinity's that have that provision?
Remarks: With an active crossover you can have a dedicated amplifier for only amplifying a portion of the frequency-spectrum dedicated by the crossoverpoints. The amplifier is less stressed by that feature.
With an Infinity (maybe apart from the IRS) both amps amplify the whole frequency-spectrum and the CU or crossover inside the speaker "blocks" the portion that's not needed to drive the units the speaker binding posts is connected with.

I operate a QLS with a Conrad Johnson EVO2000 mosfet on the midbass/mid/high section and different amps (Krell KSA-100, Perreaux PMF3150 and Denon POA-3000) on the bass section.
All the amps above are capable to drive the QLS fullrange to a SPL that's adequate to deny any conversation within 15 feet of the speakers.
- Thoughts about horizontal or vertical bi-amping?

I'm really curious about your thoughts regarding this matter.

 

[chef free]

According to a 1977 Stereo magazine article, Infinity recommended vertical bi amping for it's QLS-1 without an active crossover, due to the possibility of introducing phase shifts.

One advantage I can think of would be that you can use tubes up top, as Arnie prefered and solid state for the woofers.

 

[Zarathustra]

According to a 1977 Stereo magazine article, Infinity recommended vertical bi amping for it's QLS-1 without an active crossover, due to the possibility of introducing phase shifts.

One advantage I can think of would be that you can use tubes up top, as Arnie prefered and solid state for the woofers.

View attachment 1415759 View attachment 1415760

The first recommendation by Infinity themselves means of course two identical amps and the second preference of Nudell dictates horizontal bi-amping.

 

[chef free]

The first recommendation by Infinity themselves means of course two identical amps and the second preference of Nudell dictates horizontal bi-amping.

Not exactly, Arnie always demoed his speakers with tube power, top and bottom, however many would agree that solid state does a better job for the low end.

 

[Zarathustra]

Not exactly, Arnie always demoed his speakers with tube power, top and bottom, however many would agree that solid state does a better job for the low end.

Okay, I misread your first reaction and thought Nudell used a solid state on the Watkins and a tube amp on the rest.
Thanks for the 1977 Stereo review. Very informative and indeed due to the impedance curve and electrostatic kind low efficiency (81,5 dB/1 meter/1 Watt) for realistic SPL's you need lots of power which probably wasn't available in one package at that time.
Maybe two Audio Research D-150's (introduced in 1975) could have done the job.
But is there any other benefit, now that we have monstrous highend stereo- and mono-amplifiers that can handle that load and low efficiency (My Krell KSA-100 or CJ Evolution 2000 certainly can), to use the bi-amp provision as implemented by Infinity?

 

[kurtgo]

I bi-amped my 2.5, 4.5, RSIIb, 9.1 and RS1a. I might have missed one in there somewhere. Vertical biamping worked best with the 4.5 but horizontal was fine for the rest. I don't have specs to help with understand for those that need them. It did open them up hence more airy. Slightly bigger soundstage and to me the biggest improvement was in the bass (tighter and impactful). However, the amp(s) did make a huge difference. While for most of those using a tube amp(s) for the mids and highs and SS for the bass, in a horizontal configuration, seemed the best, when I went to vertical biamping with a beefy SS amp the 4.5 really bloomed. So, might lend credence to what you are asking about with "monstrous highend stereo - and mono- amplifiers. I used 2 Parasound 3500's, one per 4.5 to make them sound their best. This was in my room and not all amps I've had could do that. I even ran 4 amps or 3 amps, SS and tube on them and changed out the crossover to an Ashly.

 

[Zarathustra]

[QUOTE="kurtgo, post: 12448814, member: 16242"I used 2 Parasound 3500's, one per 4.5 to make them sound their best. This was in my room and not all amps I've had could do that. I even ran 4 amps or 3 amps, SS and tube on them and changed out the crossover to an Ashly.[/QUOTE]
The John Curl modified version that puts out over 2kW at 1 Ohm?

 

[Grenadeslio]

If using two identical stereo amplifiers, one per side, the same benefits of greater separation as monoblock amps provide along with more airy highs due to better filtering between the high and low frequencies each having their own filter cap. If true dual mono construction for the stereo amplifiers then even better.

 

[Zarathustra]

If using two identical stereo amplifiers, one per side, the same benefits of greater separation as monoblock amps provide along with more airy highs due to better filtering between the high and low frequencies each having their own filter cap. If true dual mono construction for the stereo amplifiers then even better.

Okay clear and you would then advocate vertical bi-amping I understand.

 

[kurtgo]

The John Curl modified version that puts out over 2kW at 1 Ohm?

Nope, not that one.

 

[Bahamayellow]

Both my Kappa 9s and 8.1s are bi amped with carver power. Although they are not high end expensive amps they do sound really nice in bi amp mode. One amp doesn’t really cut it with these. I tried with one amp but midrange and highs seem to suffer. In bi amp mode there’s no issues now. Carver Tfm 25s on the 9s and A500x on the 8.1.

 

[Zarathustra]

Nope, not that one.

But still very powerful and capable amplifiers to drive those 4.5's

 

[Zarathustra]

Yesterday I played some real heavy bass material loud from Lorde (Royals live capture -

) and heared some distortion. Swapped my Denon POA-3000 for my Krell KSA-100 Mk2 and no more distortion even at higher levels of playback. The POA-3000 is not a wimpy amp (100 lbs) but could not cope apparently with the load of the Watkins woofer a this SPL.
Another effect I noticed when I inserted the Krell in my setup to drive the Watkins that the whole sound improved considerably. It seems as the foundation it laid down at the low end made my CJ EVO2000 prosper even more. I was very impressed by this effect everything cleaned up, the bass became less sloppy more tight and controlled and the rest sounded more effortlessly, less restrained than before also at low SPL's. This effect was very clearly noticeable and I would really like to give the advice to try different setups with the bi-amp facility from your Infinity's. In my setup a beefy high-end (now moderately priced due to age) BJT amp like the Krell on the Watkins and a tube or hybrid MOSFet on the mids and highs seems to work great.

 

[chef free]

I started with an MC2200 (200 watts stereo) for my QLS-1, it was pretty impressive. Then I got a second 2200 and tried horizontal and vertical bi amping, I couldn't really tell much difference other than having separate volume controls for high and low end. Finally I tried strapping the two amps into 400 watt mono amps, that's when I really heard a difference. I think that 7 cu. ft. box lets those woofers flop around and all that extra power added control over them, it made the bass less flabby, a little tighter. So I got more out of higher power than I did from bi amping. YMMV!

 

[Zarathustra]

I started with an MC2200 (200 watts stereo) for my QLS-1, it was pretty impressive. Then I got a second 2200 and tried horizontal and vertical bi amping, I couldn't really tell much difference other than having separate volume controls for high and low end. Finally I tried strapping the two amps into 400 watt mono amps, that's when I really heard a difference. I think that 7 cu. ft. box lets those woofers flop around and all that extra power added control over them, it made the bass less flabby, a little tighter. So I got more out of higher power than I did from bi amping. YMMV!

So big mono-amplifiers did the trick for you! Strange because one would expect that because of the load when strapping the QLS-1 connectors makes it more difficult to drive it for an amp.
Did you bridge your MC-2200's or parallel them, in other words higher voltage swing or more current?

 

[chef free]

Strapping parallel here, the 8 ohm tap becomes 4 etc. Good for 400 watts, (tested to 596 at rated distortion!)

 

[Maxamillion]

I tried horizontally bi-amping my RSIIbs and it sounded disjointed to me, like I was listening to two different amps. I have a preference for the SET amp sound, so I just built the biggest SET monos I could and single-amped with them. The system sounds fantastic, much better than biamping, so good I haven't changed it since.

 

[InAp]

I horizontally biamp as well, give's best of both worlds.

 

[Zarathustra]

I tried horizontally bi-amping my RSIIbs and it sounded disjointed to me, like I was listening to two different amps. I have a preference for the SET amp sound, so I just built the biggest SET monos I could and single-amped with them. The system sounds fantastic, much better than biamping, so good I haven't changed it since.

Show us those monster SET amps.
Friend of mine has VAICS with two Emission Labs 520B's putting out 50 Watts I believe.
They're huge too but a RS-IIb fullrange....

 

[Ken Boyd]

You need to keep in mind both the RS-1Bs, the BETA's and the IRS speakers use servo bass drivers, so you would need a different amp for the low end. They measure the bass drivers to make sure they are duplicating the signal to the amps. Upper frequency speakers are much less difficult to drive and don't need the extra measures like a bass driver. The tower of mid and hi frequency of the RS-1B's are not that tough of a load, a 100 watt tube amp will drive them plenty well.

The reason stated to vertical amp over horizontal bi amp is having two bass tower loads on one power supply is more taxing than just having one demanding power. And that was when power amps were not as powerful as today.