Bi-Amping Von Schweikert speakers

Escott1377 · « **Reply #60 on:** 6 Mar 2015, 03:36 pm »

Hello all. I am new to this forum, but Albert has been helping me for years thru private email.

I have a pair of VR4jr's that I have recently bi amped.

The most difficult part has been trying to adjust the sensitivity of the 2 amps.

Can anyone please help with the mathematics? My tube amp is rated for 1.1V, my solid state for 1.31V.

I have been trying different attenuator pads on the tube side. I currently have a 12dB pad in the system, it may be just a tad too much.

I would like to know how to calculate the exact dB required, although I may just keep the inexpensive and already in place pads.

Thanks -

Eric

magister · « **Reply #61 on:** 28 Apr 2015, 02:40 am »

Eric,

I can't tell you how to do the calculations but thought I would share my experience bi-amping my IV jr's, since others may be in the same boat.

I had never bi-amped a system but wanted to try it, based on the comments I read. I tried to figure out amp sensitivity and so forth but got pretty frustrated (my technical knowledge of electronics is limited . . . ). I ended up buying an NAD C275BEE amp (solid-state). I was running a pair of tube amps as monoblocks (Golden Tube SE-40's). I reset one of the monoblocks to stereo and use it on the treble/mid section, and the NAD on the bass modules.

The NAD has a little dial on the back to set the output level. After setting up the bi-amped system, I played very familiar music and set that dial so that what I heard sounded about the same as it had previously in terms of treble/bass balance; this gave me a good starting point. Then I made some small adjustments in the output level as I continued to listen.

I might get better results if I could do the calculations, but I have been very happy with this combination; the ears seem to do a pretty good job! I cannot hear any discontinuity or lack of integration between the two halves of the speakers. Maybe I just got lucky, but this could be another way to approach bi-amping for those of us who are technically challenged.

lowtech · « **Reply #62 on:** 28 Apr 2015, 05:10 am »

Quote from: Escott1377 on 6 Mar 2015, 03:36 pm

Can anyone please help with the mathematics?

Instead, maybe consider investing in a $12 multimeter. You can simply measure the output voltage at the speaker terminals of both amplifiers while adjusting the l-pad. Use a sine wave as an input signal. You should get it dialed in perfectly in less than 5 minutes. Once you've done this you can use the same multimeter to measure both legs of the l-pad - so you can replace them with quality fixed value resistors.

Escott1377 · « **Reply #63 on:** 29 Apr 2015, 01:02 pm »

Thanks to all that responded.

I never worked out the math - but it would be very difficult in my opinion. Luckily, both my amp choices are rated for the same impedance value. Had they not been, I think that would represent quite a challenge.

I never followed up with the group, but I had several sets of attenuators, 3dB, 6dB, and 12dB to experiment with.

Thru trial and error, I ended up having Percy Audio make me a pair of 8dB attenuators for the tube amps.

That has seemed to do the trick, although my digital side can get a little bass heavy at times, mostly at louder volumes.

I have ordered a DSpeaker Core to try and help smooth out the low frequency bass.

While searching, I did find a product made by CI Audio, their VPC3, that would have solved the issue as well for about the same amount of $$ and less headache than the attenuator route - the 8dB ran me about $75 and the other 3 sets were $30 each.

If anyone does purchase the CI Audio device, I would like to know how it performs since it is a dial and not stepped.

Thanks -

Escott1377 · « **Reply #64 on:** 29 Apr 2015, 01:41 pm »

Quote from: magister on 28 Apr 2015, 02:40 am

Eric,

I can't tell you how to do the calculations but thought I would share my experience bi-amping my IV jr's, since others may be in the same boat.

I had never bi-amped a system but wanted to try it, based on the comments I read. I tried to figure out amp sensitivity and so forth but got pretty frustrated (my technical knowledge of electronics is limited . . . ). I ended up buying an NAD C275BEE amp (solid-state). I was running a pair of tube amps as monoblocks (Golden Tube SE-40's). I reset one of the monoblocks to stereo and use it on the treble/mid section, and the NAD on the bass modules.

The NAD has a little dial on the back to set the output level. After setting up the bi-amped system, I played very familiar music and set that dial so that what I heard sounded about the same as it had previously in terms of treble/bass balance; this gave me a good starting point. Then I made some small adjustments in the output level as I continued to listen.

I might get better results if I could do the calculations, but I have been very happy with this combination; the ears seem to do a pretty good job! I cannot hear any discontinuity or lack of integration between the two halves of the speakers. Maybe I just got lucky, but this could be another way to approach bi-amping for those of us who are technically challenged.

I looked at the NAD product. My tube amp is more sensitive than my solid state, so I actually have to pad the tube signal to equal the input sensitivity of the solid state.

So, not sure it would work in my situation.

Please correct me if I am wrong w/ this statement, but I thought that it is OK to add passive resistors in a system to reduce the sensitivity, but you would not want to go the the other way of introducing additional gain?

Thanks for your help -

Frankchaos · « **Reply #65 on:** 14 May 2015, 07:22 am »

Dear Albert,
thank you for starting this post on bi-amping

. I have a pair of VR-4 Gen III that I was single amping with the KR Kronzilla (2X22W stereo), fine sound, but lacking bass foundation. Then I started bi-amping with a Krell FPB600, one of the best amplifiers for a solid bass. This worked out disastrously, horrible sound, no coherence. It turned out that there was no way the Krell and the KR could work together; I know very little about electronics

, but some people who claim they do mentioned that a simple resistor would not solve the problems with these two amplifiers. Then I bought a KR VT 20 (2x50W stereo) solid state amplifier and this sounded much better, but it still lacked power. So I got a second KR VT 20 and had both converted to monoblocks by Creato Audio (Utrecht Netherlands). Now it really sounds great, I use a volume control for the mono blocks (balanced) and am using a Audio Research LS 25 II (Creato converted) pre-amp. As you stated the tube amplifier for mid/high works excellent and for a solid bass the solid state amplifiers do their job

!!
Frank

gbeard · « **Reply #66 on:** 14 May 2015, 12:07 pm »

For anyone who might be interested in trying to bi-amp without spending too much on a volume control solution for the higher gain amp, I can highly recommend Dave Slagle's Autoformers. For a little over $3 large and a bit of work, you can have a volume control that very simple, yet one of the best. The best part is, if you decide not to bi-amp, you have a terrific AVC as a second linestage for those passive moments in your life.

Should have said $3 C-notes. Not that expensive!

kernelbob · « **Reply #67 on:** 14 May 2015, 04:51 pm »

The Tortuga Audio LDR passive controllers sound great whether driving an amp full range or level matching one amp in a biamp'ed system. The light dependent resistor system is self calibrating, so impedance drift is a non-issue. They also have user adjustable input impedance from 1 to 99 kohms (you can change it on the fly from the remote). That's a useful feature to optimize the impedance presented by different types of amps on the bass versus mid/tweeter amp as well as selecting an input impedance where your source component sounds best. You can get a balanced version for around $1700 and a single ended version for around $1100. I've replaced my active pre-amp with the LDR1-V2B balanced model. Not only less expensive, but with better sound.

gbeard · « **Reply #68 on:** 14 May 2015, 05:07 pm »

Hello KB,

I forgot about your LDR. Still haven't tried one. Good to meet you at the show, it was a fun weekend. (Sorry about the hijack...back to the regular biamp thread)

Gary

nc42acc · « **Reply #69 on:** 2 Jan 2016, 07:18 pm »

I have had my VR5 anniversary MKII for about 6 months and have had much better luck using mono amps biwired. I think Alberts main reason for recommending a tube amp on the uppers is he made them so dang revealing they are relentless on a bad sounding front end. I am thinking the tubes are to mellow out the uppers. I hope Albert or Damon reads and replies. I want to thank Von Schweikert for producing such revealing speakers. Truly amazing.

walterslw · « **Reply #70 on:** 9 Apr 2016, 11:53 pm »

Hi Nc42aac

Congrats on the VR5 Annies MK II. I too have the same speaker, I purchased the last set - prior to some additional pairs being made available. Ive owned the Vr5s for 1.5 years now, and couldn't be happier! You may have seen some of my previous posts. I have tried a few tube amps, and solid state bi-amping, and I have to say that tube on the top, solid state on the bottom is the way to go (in my experience). I recently (6 months or so) acquired a used Sonic Frontiers Power 1, completely re-built and upgraded by Parts Conexxion. The changes made to the stock power 1 were extensive upgrades, but main change is increasing the plate voltage so that the amp can accommodate the new KT 120 tubes. The new Power 1 delivers about 70 watts into 8 ohms for the top, and my Bryston 7B SST^2 deliver around 600 watts into 8 ohm - so there is no shortage of power.

I had Chris match the input sensitivity and gain of the Power 1 tube amp to that of the Bryston monoblocks. So no passive attenuators are required anywhere in my signal path. With the sonic Frontiers Power 1 (Platinum SE upgrade) there is no rolling off of the top end, or smoothing. Almost the opposite, it almost sounds like a solid state amp - WITH the magic of tube midrange. The soundstage is wide and deep, but the midrange is better than any solid state amp that I have heard. Anyway - sorry to ramble

I agree, these speakers will reveal any weak link upstream. Vacuum tubes in pre-amp, power cords, cables, isolation, everything!. It took me 6-8 months of tuning my system, but the major win for me was when I changed to the above bi-amping set up. I feel the VR5 Annies really come alive with a properly set up bi-amped configuration.

Let us know how you make out!

es347 · « **Reply #71 on:** 10 Apr 2016, 01:10 pm »

I'm driving my VR5 Annies with McIntosh amplification...C500P preamp and MC601 monoblocks. I also am running a pr of Velodyne Optimum 12 subs crossed over at 60hz. Me like!

walterslw · « **Reply #72 on:** 18 Apr 2016, 08:13 pm »

Quote from: es347 on 10 Apr 2016, 01:10 pm

I'm driving my VR5 Annies with McIntosh amplification...C500P preamp and MC601 monoblocks. I also am running a pr of Velodyne Optimum 12 subs crossed over at 60hz. Me like!

NICE! es347 - what are the dimensions of your room? Do you situate the subs right beside - or behind - the vr5? Adding a pair of subs is something I would like to explore in the future. Any base humps or weird anomalies?

es347 · « **Reply #73 on:** 18 Apr 2016, 08:57 pm »

16W x 30D x 10H...no weird bass humps or dips

KWF · « **Reply #74 on:** 20 Nov 2016, 07:08 pm »

Hello -- new to this forum, but have followed this thread with much interest, as it inspired me to biamp my VS 4.5s about five years ago. I have a Dared tube amp with a volume control on the top, and an Emotiva solid state amp (without a volume control) on the bottom. The tube amp's input sensitivity is 250 mv... and the solid state amp's is 1.1 v.

I love the sound I'm getting from the current setup, but am thinking it could be even better, so... recently I had the tube amp modded with a switch to optionally bypass the volume control, and (you can probably guess where this is heading). I would like to swap out the Emotiva for a solid state amp with a volume control, but have not been able to find one with a viable input sensitivity.

Suggestions anyone? I'm not interested in getting a different tube amp, or padding the tube amp's output -- just in finding a SS amp that will work as per the preceding... preferably a power amp with volume controls, not an integrated amp.

TIA.

JackD201 · « **Reply #75 on:** 29 Nov 2016, 06:33 pm »

I believe Parasound Halos have input sensitivity trims at the rear

Escott1377 · « **Reply #76 on:** 29 Nov 2016, 06:55 pm »

NAD is an option.

I recommend this as a much less expensive option that will allow you to obtain the same results and is completely passive.

http://ciaudio.com/products/VPC3

KWF · « **Reply #77 on:** 30 Nov 2016, 05:20 am »

Both recommendations are appreciated. Thank you.

KWF · « **Reply #78 on:** 2 Dec 2016, 04:09 pm »

....but unless I'm missing something, neither of the suggestions are quite what I was hoping for.

I want the volume control to be on the front of the SS amp -- the input sensitivity should be 250 mv or better. Currently I'm using the volume control on the tube amp as a primitive tone control, and it works quite well in that I listen to a wide range of material with some being a bit too bright (the most common problem), and some not bright enough. So "treble adjustment' is very important to me (and my pre-amp, an AR SP-16 does not have tone controls).

Now that I have a bypass switch on my tube amp, and can skip the tube amp's volume control entirely, I am getting a sense of the sleight veiling the volume control has been adding all these years. But I don't want to lose the capability of making fine adjustments to the bass vs. MT balance, so rather than attenuating MT via the tube amp, I want to be able to achieve the same result by boosting bass on the SS amp.

So why not just use a better attenuator on the tube amp? That may end up being my last resort, but another issue is that I often listen to (old-school, not modern brickwalled) CDs and 24/96 or 24/192 FLACs at about 75%-80% max volume on my pre-amp. If I can run my tube amp with the bypass switch engaged it, and have the SS amp "make up the difference", the overall effect will be to move that average volume level down to 65%-70% on my pre-amp.

So, an SS power amp (not integrated) with volume controls on front, plenty of watts per channel, and, say 200 mv input sensitivity. Suggestions/recommendations anyone?

Escott1377 · « **Reply #79 on:** 2 Dec 2016, 04:17 pm »

That little CI Audio device allows for variable control on both inputs via a jumper switch.

I went thru lots of research and trial & error to get my 4jr's sounding the right way.

I had 7 dB custom attenuators made for my tube amp.

Ultimately, when my jr's went back in for the latest upgrade they came back @ 4 Ohm impedance and that fixed the problem w/o the requirement of attenuation.

For $375, I recommend trying that CI Audio device and asking about the return policy. You can always try it and hopefully return it w/o having to purchase another amp.

Just my $0.02 - I have a friend that uses it and was blown away once he was able to adjust the levels on his bi amp set up.

Also, I use 2 x powered subs crossed over @ 50 Hz to really even out my bottom end. Not terribly loud, just enough to know they are there.

Good luck -