Noob question

[Alcatrax]

Hi

I recently purchased a pre-loved pair of ML Vistas. Prior to acquiring them I had a pair of Kef iQ9's powered by a Yamaha AVR - the Aventage RX-A810.

I was pretty sure that the Yamaha amp would have trouble driving the Vistas (it even had trouble with the iQ9s), and sure enough the amp protection circuitry kicked in about a minute into Dark Side of the Moon.

I had a spare QSC 2450 PA power amp laying around, so I have hooked up the Vistas to that. I am using the Yamaha as a pre-amp for the QSC and driving my sub and rear speakers using the Yamaha for cinema sound. For listening to music I use only the MLs.

My concern is that the power amp will be too powerful for the Vistas. The specs are:

OUTPUT POWER in watts
FTC: 20 Hz–20 kHz @ 0.1% THD, both channels driven
8 ohms per channel 450
4 ohms per channel 650

EIA: 1 kHz @ 0.1% THD, both channels driven
8 ohms per channel 500
4 ohms per channel 750

1 kHz @ 1% THD, typical, both channels driven
2 ohms per channel 1200

DYNAMIC HEADROOM 2 dB @ 4 ohms
DISTORTION SMPTE-IM < 0.02%
FREQUENCY RESPONSE20 Hz–20 kHz, +0/-1 dB
(at 10 dB below rated output power) -3 dB points: 5 Hz and 50 kHz
DAMPING FACTOR > 300 @ 8 ohms
NOISE (unweighted 20 Hz to 20 kHz, below rated output) 100 dB
VOLTAGE GAIN 50× (34 dB)
INPUT SENSITIVITY, V RMS full rated power @ 8 ohms 1.23v (+4.0 dBu)
INPUT IMPEDANCE 10K ohms unbalanced
20K ohms balanced

My plan is to use the QSC amp until I find a suitable used hifi power amp to replace it, but in the meantime do you think it is safe to use it? It drives the Vistas really nicely to my ears but can't be as musical as a proper hifi power amp can it?

My room is only 4.5 meters square, so I am guessing that my ears would be bleeding before the speakers could be damaged, but I really don't know, so any advice on my options would be gratefully received.

I would like to continue to use the Yamaha amp as a pre-amp as it has some useful features.

Many thanks

Peter G

 

[Bernard]

You got it right - you would destroy your hearing before you destroyed your speakers.

 

[edwinr]

I too, had problems with home theater receivers driving my Theos speakers. After trying a few different models, I found the Denon 3313 could drive them without switching off. Most modern receivers function well as preamps, as you've found out.

Regarding your power amp concerns, the Vistas and the Theos can take enormous amounts of power without hurting them. While lower powered amps can drive them, the Vistas will obviously sound more dynamic with more capable amps. The important statistic with the QSC 2450 is it's ability to drive very low impedance loads. The high wattage output is a bonus. The draw back of many professional amplifiers, is that they're fan cooled and are not generally designed with quite listening in mind. If the fan noise isn't a concern, why even consider changing this power amp if you like the sound?

 

[Alcatrax]

Thanks very much for the input.

The fan noise isn't too bad and is inaudible if the speakers are operating. I think I will stick with them for a while and be sure to audition any possible replacement to ascertain whether I can hear sufficient improvement in quality to make it worth replacing them.

 

[T Diddy]

Hi, I also just purchased some very gently used Vistas. I am driving them with a Denon 3313. Not 10 minutes ago the Denon shut down. I was hitting a sweet spot with a little Big Head Todd...I have been looking for an amp, but really want to make it count...without killing my wallet...I am a low budget kind of person..I have been looking at Anthem and Emotiva... I worried the same thing. Although those won't be over powered...Most of the Amp stuff goes way over my head...but I know what sounds good to me...And it was sounding very good to me until my Denon clicked off. As far as I can tell you will be fine with power to the Vistas...just keep it within reason, but I think they can take it.
T.

 

[vette69]

The Vistas can take (and love) a substantial amount of clean power. edwinr is correct about the impedance swings of these speakers. The weal link on power handling (given impedance swing) is the low section....the Vistas 8 inch woofer can be overdriven with substantial low frequency content. I have had no poblems with my Vistas, driven at any volume level, until the arrival of the new Zep Celebration Day BD disc. Th first time in over a year I heard one woofer cry (bottom out but no damage), but that may have been an over zealous applicaion of the + side of the volume control. These speakers will take an enormous amount of power, but the bottom end does have limits. I have fed them peaks of over 400 watts per channel with no problems. Sans any fan noises, your QSC should e a good match with the Vistas until you want to venture in a different direction in the amp section.

 

[edwinr]

Hi, I also just purchased some very gently used Vistas. I am driving them with a Denon 3313. Not 10 minutes ago the Denon shut down.

Please, please don't tell me that :stop:

 

[MrBT]

Some time ago, just for shi** and giggles I plugged Vistas to 3310. The result was......hmmm....let's say: If this would have been my first contact with ML speakers I would probably be heading other direction now. This receiver stripped Vistas from all it's charm.

You guys purchased very fine speaker, which deserves much better than just a receiver

 

[MickeyVee]

Maybe - there are some quite capable AVR's out there. I'm using a Rotel AVR RSX-1560 and I've read/seen people with the Arcam AVR-600 driving the Vista's with great results. Mind you, these are not your regular consumer AVR's and they can drive the Vista's quote nicely.
When I got my 1560, I purchased an external Rotel amp, 2x250 into 8 ohms and 2x500 into 4. I moved into a new home about a year later, was too lazy to setup the external amp and found that the AVR did quite nicely. Ended up selling the amp.
Given that, I would love to add a kick but external amp in the McIntosh, Krell, Pass Labs range but I'm pretty happy with the Rotel.

You guys purchased very fine speaker, which deserves much better than just a receiver

 

[T Diddy]

Please, please don't tell me that :stop:

Yeppers...And I swear it was just sounding awesome, I moved to the couch and my "sweet spot" planted my butt down and...off it went. Reset and jammed the rest of the evening with no problems...but I do agree, the Vistas deserve much more. I am looking, but it is the Holidays and my wallet is light on funds and heavy on debt! I am doing a lot of research on amps...what I want, I cannot afford, so I keep researching...I have read every thread here about amps. And on just about every other site...I think for my budget, I can save and get an Anthem...any other suggestions are welcome...needs to push a Motif also for tv/movies....Hope I didn't hijack or anything, but we seem to be in the same boat.
T.

 

[gordonmenninger]

Forget about Yamaha receivers... You are now in semi - high end territory with your ML speakers and Yamaha and QSC has no business being hooked up to your new toys! A yamaha receiver putting out 100 watts may be ok for background music, but for serious listening it will shut down because it is just not up for the task.
Your QSC amp has the right amount of power but those amps are basically just built for their ruggedness and not for sound quality! Buy a nice used amp on audiogon and make those puppies sing and give them what they deserve. Depending on budget I would suggest Sunfire Cinema Grand (budget), Bryston, Krell, Pass for great sound!
Good luck in your endeavor!

 

[Alcatrax]

Thanks for all the great advice. You have given me a lot to think about.

 

[edwinr]

If we're going down the path of upgrading the power amplifier, looking at the classics may be a good idea, and it'll be cost effective. What about one of the old DR series Classe power amps? A DR15 wouldn't be over kill, and these amplifiers are built to last a life time.

While you're looking for the power amplifier, consider a classic Audio Research preamp. I like the SP9. You can get these amps for a song these days. For a few dollars, get it tested and upgrade the caps if needed. I would keep the Yamaha to run just the surround speakers, running the preamp/power amp to power the Vistas and for all 2 channel stuff.