VSA VR-4: problem with midrange drivers


I recently bought a pair of original VR-4's. They sounded great except when playing certain discs at higher volumes. Then I had some distortion from one or both mids. I am driving the top end with a 200 wpc B&K ex442, same for the bottom (bi-amped). Called VS and they were helpful, thought that the voice coils had probably been overheated at some time...I replaced them yesterday with the upgraded drivers.
Again, with certain discs I seem to be hearing some clipping at higher volumes...say about the 11:00 position on my AR LS3B pre. Sounds potentially like my amp is clipping.
Question is, if I use a lower powered amp on the top end ( I have a 100 wpc Aragon not currently in use) would that make any sense? I will also have the B&K checked out to see if there are any issues with it, but I'm concerned that sending 200 watts to the upper and 200 to the lower speaker modules is why I'm having the issue. The VR4's are rated at 250 wpc.
pjnad
I would start by using another amp entirely. Have you tried them in NON-biamped config? That's where I would start before replacing speaker drivers, or sending amps in for service. Also, if you have identical amps I would vertically biamp them, though this shouldn't effect the issue you have.

I have VR4 gen III's and they don't require 200 watts to sound good (indeed they sound wonderful with a 35 watt tube amp (non-biamped), and I normally drive them with a 140 watt ss amps in vertical biamp config. So testing them with your lower power amp shouldn't be an issue at all. Also, unless there's a significant sensitivity difference with your top and bottom amp, driving the mid/hi module with the EX442 shouldn't be an issue either.
If I use a lower powered amp on the top end ( I have a 100 wpc Aragon not currently in use) would that make any sense? I will also have the B&K checked out to see if there are any issues with it, but I'm concerned that sending 200 watts to the upper and 200 to the lower speaker modules is why I'm having the issue.
If the problem is amplifier clipping, using a lower powered amp (for either the lows or the highs) will make matters worse, not better.

Also, you are not "sending 200 watts to the upper and 200 to the lower." The power you are sending to each is determined by the music, the volume control setting, and the speaker efficiency, as long as the amplifiers' maximum power capability is not exceeded. And keep in mind that music almost invariably has most of its energy concentrated in the lower part of the spectrum.

Keep in mind also that if you biamp with two different model amps, especially ones with different power ratings, if their gains are not the same you would be introducing a volume imbalance between the lows and highs in horizontal biamp configuration, or between channels in vertical biamp configuration (vertical biamping with different amps of course not making sense for other reasons as well).

I second BDGregory's suggestions about how to go about addressing the problem itself.

Regards,
-- Al
Thanks guys. I understand that I am not sending the 200 watts to either module per se, that it is dependent on the source recording, and where I have my volume set...my concern was that perhaps the drivers in the top module weren't capable of handling that much power alone.
I thought about running the speakers with just one amp...I have a good set of jumper cables that were part of my purchase, but the VSA manual does suggest that they will sound better bi-wired or bi-amped.
Also, I am not clear as to how to vertically bi-amp. My speaker cables are not identical, I'm using MIT on the bottom end and Synergistic on the top.
VSA manual does suggest that they will sound better bi-wired or bi-amped.
Also, I am not clear as to how to vertically bi-amp. My speaker cables are not identical, I'm using MIT on the bottom end and Synergistic on the top.

I called VSA when I bought my VR4s - Albert answered the phone personally on the second ring! I asked him about biamping or using a single high powered amp (I was considering having my Eagle 4's converted to Eagle 11 mono blocks. He said they're best when biamped. I've since tried them with several different amps and none best Eagle 4s in vertical biamp config.

Vertical biamping is easy - but you need identical amps. One stereo amp goes to one speaker, the second to the other. Connect one channel of each amp to the mid/hi, one channel to the bass. You can use different cables for mid/high if you like. There is a biamping thread in the archives where Steve McCormack describes at length why vertical biamping preferred when you're passively biamping. It's worth a read Here.. he also discusses using different cables . . .
Got it...I think. What about my preamp. Do I need to reconfig my interconnects? Sending only left info to the left and right info to the right? My interconnects (2 pair) and not identical, I am running audio horizons to my amp that powers the lows and purist audio to the amp for the highs.
Thanks for the help.
paul
My concern was that perhaps the drivers in the top module weren't capable of handling that much power alone.
To clarify my previous comments a little further, the mid/hi speaker drivers will see exactly the same amount of power when bi-amped as when the speakers are single-amped, assuming identical volume levels.

The voltage at the output of the amp channel driving the mid/hi section will be the same as at the output of the amp channel driving the low frequency section (at least in the case of a typical solid state amp having low output impedance), and will also be the same as for a single-amp configuration.

The current flowing into the mid/hi section as a result of that voltage will be limited by the speaker's crossover so as to correspond only to the mid/hi frequency content of the music, just as would occur in single-amp configuration. Therefore the power delivered by the amp to the mid/hi section, being proportional to voltage x current, will not change as a result of bi-amping.

The bi-amp configuration will, of course, make life somewhat easier for the amps, by reducing the amount of current and power that must be supplied by each amp channel (since each channel will only be powering one section of a speaker rather than both).

Re your last post, yes for vertical bi-amping the left channel output of the preamp should go to both channels of the left power amp, and the right channel output of the preamp should go to both channels of the right power amp.

Regards,
-- Al
Thanks,Al. I have rewired and am now in vertical bi-amping mode. I'm about to sit down and listen. So...if there is a problem with one of my amps ( the clipping previously noted) I should now only experience it from the channel that that amp is driving.
I guess that I'm hoping that if I still have that issue, it's an easier fix than anything else. It seems to me, that these speakers ( drivers ) should be able to handle the volume that I'm throwing at them. My pre is a Audio Research LS3b and again, the clipping/distortion occurs when I have the gain control up around the 11:00 position. My previous speakers were B&W 704's which were also biamped, and while they didn't sound entirely great at that volume, I never noticed a similar issue...
Paul
as for interconnects - you can run one IC to each amp and use a Y splitter at the amp, or you can use the Y splitter at the preamp (or if your pre has 2 outputs use those) and run 2 IC's to each amp. My IC's are long so I do the former using some good quality Audioquest splitters. I have my amps sitting next to my speakers so I can have short speaker cables

If you're brave, you can also open up your amp and solder a short jumper between the + terminals of the 2 RCA connectors, but then you need to be careful to remove it before you use the amp for stereo again. This may have an advantage technically over splitters and double IC's. This isn't something I was comfortable with though.

I'm not sure how loud the VR's will play and have never put a db meter on mine, but mine will play louder than I'm comfortable listening at . . . this I know.
So...after some listening I have determined that the culprit is one of my B&K amps. Having succesfully vertically biamped the speakers, using the amp that had originally been powering the mid/hi module, for the left channel...the clipping distortion was present in that left channel. The right channel, with the other amp, seems to be fine.
I have a friend here who will be taking a look at the amp to see what might be going on...
And, yes the vertical rather than horizontal biamping set-up gives me better seperation and perhaps a bit more clarity.