Bi-Amping Von Schweikert speakers

es347 · « **Reply #20 on:** 3 Oct 2008, 02:47 pm »

Thanks for the quick reply Jack (btw nice M3...sold my 98 sedan last year

) I'll quit worrying about the crossover. If these speakers actually whip the watt puppies as some say they do, that's good enough for me considering the $20K price difference. I auditioned the wilsons and liked them so sounds like I will like the SR mkII ever more. Do you see any problem driving them with the McIntosh MC252 SS power amp and the MC46 pre? If the speakers are as neutral as Mr. Von Schweikert says they are, a solid state amp as good as the MAC shouldn't sound overly bright or sizzly. Anyway, that's my story and I'm sticking to it.

JackD201 · « **Reply #21 on:** 3 Oct 2008, 04:35 pm »

The MC252 should drive the SR IIs as easily as Schumacher can drive a go-kart. The SR Mk1s definitely preferred tubes and all the Mk1s in the Philippines are powered by tube power amps. The Mk1s had a slight upper midrange rise that exposed any shrillness or grain an amp might have. This was addressed with the Mk2 and as a result most SR Mk2s here are powered by solid state amps. If you've been reading between the lines you might have inferred that the SS owning Mk1 owners switched to tubes while the SS owning Mk2 owners stuck to what they already had. That is indeed what transpired.

Expect a walk-in stage with the SRs vis a vis a Puppy 6,7 or 8 neatly laid out stage. A major attribute of SRs is that they image well from almost anywhere in the room (very important to me since I entertain a lot). Image outlines are more rounded than the WP's. Think a fountain pen compared to a tech pen. The SRs are warmer and fuller while the Wilson WP's emphasis is on lightning quick transient response. These are more matters of taste however and while they do differ greatly both are excellent.

Yes my M3 is beauty. I get ribbed a lot when people say the VR9s cost more than my car. My answer is that I don't have potholes or traffic jams in the listening room

"Grain of Salt" time as this is just my personal opinion

The SRs will definitely give the Puppies a run. $20,000 makes for lots of LPs and CDs!

blownrx7 · « **Reply #22 on:** 3 Oct 2008, 06:01 pm »

How do you properly attenuate a balanced (XLR) connection?

Albert Von Schweikert · « **Reply #23 on:** 6 Oct 2008, 04:08 am »

This thread is very interesting to me because I have seen so many other opinions that seemed to make it very complicated to bi-amp.
Active crossover, bypass the internal speaker crossover, set the crossover frequency above the speaker crossover frequency, etc, etc.

Now here comes Mr Von Schweikert. Certainly someone we all feel is an authoritative source of knowledge and he promotes the easiest of solutions to implement. Now, I don't need to stress over buying yet another piece of equipment (the crossover), and I don't have to mess with the internals of the speaker and I don't have to figure out if the crossover frequency I've chose is correct.

All I have to do is run the amps to the speakers and if the amps have different sensitivities, pop in a resistor. What could be easier?
Am I missing something?
If someone get the resistor value formula, please post it here.
TIA

Proud VR4.5 owner

from AVS:
I am gratified to see so many audiophiles interested in trying a "biamp" configuration, even though it is not easy to achieve. In my original post, I alluded that amplifier matching could be accomplished by using resistors to attenuate the louder of two amplifiers that do not have matching SPL levels with the same input volume. I wish to expand on this topic, with the following additional information, below.

First, depending on the actual gain of the amplifier's input and output stages, the most sensitive amplifier (as rated by "input sensitivity" in mV) may be the loudest amplifier in a "passive bi-amp" configuration. However, as we don't know the actual gain configuration of these amplifiers, the closest input sensitivity value would be the "best guess" at this time. It is actually best to use a solid state bass amp with a higher gain and input sensitivity, and use an outboard attenuator to reduce this amplifier's output, see more about this idea below.

Calculating the additional resistance to be added to the amplifier with the loudest SPL is straight forward, but requires that we know the "gain" of the amplifier design. If you have been following this topic at the LAB section, it has been noted that the gain can be measured by using a SPL meter and pink noise, then using the formulas to calculate the additional resistor required. My thanks to JoshK and jeffreybehr for their input, see their latest posts at THE LAB.

In my experience, it is easy to accomplish the level matching by using an external attenuator to find the correct resistor value, then installing that value into the input jacks of the amplifier. However, for best results, the amplifier designer should be consulted, as adding a resistor inside the amplifier may void the warranty, while using the outboard attenuator will not.

Channel Islands Audio, one of the Audio Circle Members, offers the VPC-3, which can be inserted in the signal path before the amplifier that is playing the loudest. Use Pink Noise and a RTA (or your ears) to match the levels of bass-to-midrange/treble. Using music to balance the two amplifiers is difficult, since you will need to play a wide variety of tunes to get a feel for the balance, while using Pink Noise is far easier.

I have found that using the attenuator for the bass amplifier works the best, since the very slight sonic "veiling" is not readily apparent in the bass, but is more audible in the upper midrange/treble area. This is not due solely to the potentiometer in the attenuation box, but also the extra connections and necessary interconnects. In the bass range, the added "veil" is not audible.

If you have balanced inputs and outputs, you can make an adapter to convert RCA to XLR when using the Channel Islands attenuator; contact Michael Percy at www.percyaudio.com for further info.

Albert Von Schweikert

duguyisheng · « **Reply #24 on:** 14 Oct 2008, 05:23 pm »

In the very first post in this thread, it is suggested that for biamping (I am interested in VR5), one should use 200-300 watts for the bass module which is 4 Ohm. Many amps are 150 watts in 8 ohms and 300 in 4 ohms. Are you referring to 200-300 W in 8 ohms (and 4-600 in 4 ohms) or 150 in 8 ohms (and thus 300 in 4 ohms). Thanks.

VSA_JOE · « **Reply #25 on:** 15 Oct 2008, 05:56 pm »

Good morning Duguy, Albert was referring to a 6 ohm load which is the speakers average impedance load. The actual power output is not important as the actual sound of the amplifier. Nearly all amplifiers can be partnered for bi-amp, what we are looking for mainly is a tight bass amp with enough power to drive the woofers ( 100 watts - 500 watts per channel ) and a smooth sounding amplifier for the mid range and tweeter. Since most amps do not have equal sound quality from bass to treble, you now have the opportunity to choose the best amp for the bass sound, and the best amp for the mid range tweeter sound. In general, large solid state amps have the best bass and small tube amps have the smoothest and sweetest mid range and treble tones. The power ratings are not as important as the actual tone quality of the amplifiers. By the way, do you have a local dealer that has demoed the VR-5 for you? What amplifiers does he carry? If you are interested in the VR-5, Albert would accept a direct phone call at the factory (951-696-3662) to talk to you about amplifiers.

randybarba · « **Reply #26 on:** 20 Oct 2008, 03:29 am »

How do I biamp my vr4jrs if my preamp only has one pair or outputs? Is it OK to use a y-splitter for this purpose?

Thanks,

Randy

JackD201 · « **Reply #27 on:** 20 Oct 2008, 04:08 am »

Quote from: randybarba on 20 Oct 2008, 03:29 am

How do I biamp my vr4jrs if my preamp only has one pair or outputs? Is it OK to use a y-splitter for this purpose?

Thanks,

Randy

Doc,

Have Harana install a second pair of outputs

Jack

BTW

Just grab the ICs from Hyper. I'm all out bro.

stewie · « **Reply #28 on:** 20 Oct 2008, 05:22 am »

Question for VSA Joe or others. If one's SS power amp has potentiometers (R&L), does that circumvent the need for resistors in the input jacks? In other words, will the ss power amp potentiometers proportionally reduce the output so that one may easily match the ss amp to the tube amp output? Thanks.

JackD201 · « **Reply #29 on:** 20 Oct 2008, 07:24 am »

Quote from: stewie on 20 Oct 2008, 05:22 am

Question for VSA Joe or others. If one's SS power amp has potentiometers (R&L), does that circumvent the need for resistors in the input jacks? In other words, will the ss power amp potentiometers proportionally reduce the output so that one may easily match the ss amp to the tube amp output? Thanks.

pretty much

randybarba · « **Reply #30 on:** 21 Oct 2008, 01:11 pm »

Quote from: JackD201 on 20 Oct 2008, 04:08 am

Quote from: randybarba on 20 Oct 2008, 03:29 am
How do I biamp my vr4jrs if my preamp only has one pair or outputs? Is it OK to use a y-splitter for this purpose?

Thanks,

Randy

Doc,

Have Harana install a second pair of outputs

Jack

BTW

Just grab the ICs from Hyper. I'm all out bro.

Thanks Jack. Will text hyper

msm_1 · « **Reply #31 on:** 24 Oct 2008, 10:21 pm »

Hi

I planned on running a pair of tubed Rogue Audio 88's (40-60/channel) with my VR-4's but was told that these were not the best of match with VSA's due to the cathode bias they use and said I'd be better to upgrade to the ST-90's at $1100.00 each plus tax and shipping (from Canada which won't be cheap and the way the Canadian dollar is, ouch!!).

http://www.rogueaudio.com/manuals/88_Manual.pdf

I already own the pair (one needs a repair as it keeps blowing tubes) so I wasn't expecting the negative reply I received when I told them (Rogue Audio) the speakers I was using.

Any suggestions as to whether this would be a good match?

Thanks

Mike

JackD201 · « **Reply #32 on:** 26 Oct 2008, 05:45 am »

Rogue blamed the blowing tubes on the speaker?

Any respectable tube amp should be able to handle anything from the 4ohm taps except perhaps speakers with extreme impedance dips which no VR has.

Rogue has a reputation for making good sounding, robust amps. I can't see why a CJ MV55 or MV60 or even the little Manley Stingray can drive a 4 HSE without blowing up and the 88 can't. Would you mind PMing me Rogue's reply and I'll ask our tech what a cathode rectifier should have to do with speaker matching. Thanks!

msm_1 · « **Reply #33 on:** 26 Oct 2008, 12:16 pm »

Hi

I sent a PM to you....Thanks

The one 88 amp was already in need of fixing when I contacted Rogue about repairing it, so no, the 4's were not the Rogue's problem. The reply I received back, after sending a email regarding a repair, stated that the 88's were not a good match to VSA speakers due to that cathode bias, and suggested to go to the ST-90 amp instead.

Thanks

Mike

JackD201 · « **Reply #34 on:** 26 Oct 2008, 03:51 pm »

Whew! I'm glad I proved myself a bonehead by getting your post all wrong. The guys at Rogue are good guys and the local Rogue dealer is a great guy as well. I know for a fact he's had no problems whatsoever with the Rogue products he's sold here over the years. I researched Rogue thoroughly in the past and considered bringing their line in at one point and research showed them to be reliable and reputable. I passed on Rogue not for lack of quality but rather Rogue did not have the "Cache" here in the Philippines at that time.

I felt we didn't have the time to build up the brand as we were concentrating on VSA. We did that by literally bringing the loudspeakers around the audiophile circuit. The audiophile version of a tupperware party but we knew the only way we could get the word out was from positive home based experiences filling the word of mouth. There was also the novelty of a Congressman and an Investment Banker lugging speakers around door to door

It took a lot of energy. The brand got it's name and reputation back, we honed our set up skills but were just too spent to go marketing another brand from scratch. A problem we didn't have when we decided on Lamm and their countless reviews. We just got the word out and people just started trouping to the showroom. The powers of the audiophile mainstream press can not be denied.

I'll still ask my tech in what way a cathode rectifier matters in a push pull amp when it comes to speaker matching. I have no reason not to believe Mark and the guys at Rogue. They know their amps better than anyone else. I'm just genuinely curious.

msm_1 · « **Reply #35 on:** 28 Oct 2008, 02:13 am »

Thanks Jack

Since I already own these I would like to run them. With the cost of the CDN dollar compared to the US, I can't see myself getting the upgrades on these till it's closer to par. So I will send the amp to get repaired and try running bi-amped. As of now, the DR-8's work great but that's not really what I wanted to run with them.

My dealer also wanted to know if I would be interested in the upgrade to the VR-5 specs, and at a great price, compared to the VR-5's he has on the floor!! But, the condition these are in and the chance of not liking the final result, makes me hesitate a bit!!

Thanks

Mike

blownrx7 · « **Reply #36 on:** 7 Nov 2008, 09:20 pm »

Still trying to figure this out but I'm getting close.
I'm hoping a VSA person knows this.

What is the nominal impedance of the woofer cabinet for the VR4.5 and what is the nominal impedance for the mid/tweeter cabinet?
The specs just say 6 ohms nominal for the entire speaker but I'm guessing the two cabinets differ.
TIA

JackD201 · « **Reply #37 on:** 17 Oct 2012, 05:31 am »

IIRC 8ohms for the MT module and 4 ohms for the bass modules.

boe · « **Reply #38 on:** 1 Feb 2014, 04:31 pm »

Does it matter when you bi-wire if you plug the banana connectors from the amp to the sub binding posts or the tweeter-midrange posts on the bottom? They are both connected on the bottom of the speakers I would imagine.

kernelbob · « **Reply #39 on:** 1 Feb 2014, 05:59 pm »

Hi boe,
For biwiring (as opposed to biamping), you want to connect the single pair of connectors ( +,-) to the amplifier; one of the biwire pair (+,-) to the top terminals (mid/tweeter); and the other biwire pair (+,-) to the bass module terminals on the bottom. If your speakers have an additional pair of terminals on the bass module to allow a single run from the amp to the bass module, jumpered to that other pair or terminals, you don't want to use those-- connect the mid/tweeter module to the amp directly to the amp, not jumpered from/to the bass module. By the way, if there are jumper plates between the bottom terminals, you should remove those.

The point is that the mid/tweeter crossover (which is independent of the bass crossover) has high impedance in the bass frequencies so bass current doesn't flow significantly through the mid/tweeter speaker cable. That avoids the relatively high current of the bass frequencies from interacting with the mid/tweeter frequencies on their way from the amp to the mid/tweeter terminals.

If you just jumper the mid/tweeter and bass connections at the speaker, you lose this benefit and essentially aren't biwiring.

Biamping, of course, gives you that benefit also since you would be running completely separate connections from amp A to the mid/tweeter and amp B to the woofer. Biamping can give you the opportunity to use an amp that excels in the mid/tweeter range on top and a beefier amp with, say, high damping factor to drive the bass module. On the other hand, biamping can have its own issues with seamlessly integrating the qualities of the two amps without audible anomalies.

Hope this is helpful.