Two amps - The 'better' one can't handle my speakers. The 'lesser' one owns them.

The speakers are my Mirage M-5si's, which have a power handling rating of 70-200 watts, sensitivity of 84db, and a 6ohm nominal/4ohm minimum impedance rating.

I mostly played these with a Sony N77ES/E77ESD combo, which obviously had no trouble with them.

Months ago, before I sold it, I had a Kenwood KA-8150. A heavy, 4-ohm stable, dual-power-supply amp rated at 75wpc into 8 ohms. When I hooked these speakers to that, it was utter fail. Even with the knob cranked past 12 o clock, it simply couldn't open the Mirages up. They sounded like they were under a mattress. This was an amp that never failed to perform with any other speakers I used.

I'm trying to sell these speakers and was looking for an amp to demo them for a friend. My only options are both receivers, one a Kenwood KR-1000, which is 4-ohm stable and packs 120wpc or something like that. But, it's huge and weighs a ton and I didn't feel like pulling it out.

So, solely on the virtue of being much lighter, out comes a very modest Onkyo TX-860 that is one of the first peices of audio gear I ever bought. Single large-ish transformer, not especially heavy (25lbs?), 80wpc into 8 ohms, but it's rated to deal with 4 ohm loads. I completely expected it to fail like the Kenny did.

The Oinker has been driving these speakers with real authority for the past 3 hours and isn't even hot. Not bad for a random find from years ago. Sounds good too, a lot like the Onkyo Integra A-8087 I used to have.

So, what exactly am I missing here? Is there some other spec I should be looking at that would explain the difference? I honestly believe that the Kenwood should've been the heavier hitter of the two.

My buddy didn't buy the speakers, btw. His wife shut him down.

It seems the Mirage Speakers may go lower at times below 4 ohms and the
Onkyo seems to handle the lower ohms better, I hope your keeping the Onkyo
they did made some nice stuff years ago.

Tube

I would guess that the Kenwood was just not a good match for the Mirage speakers, even though it looked promising on paper. I owned a KA-8100 -- the same amp with a silver faceplate -- and sold it because it never brought out the best in my B&O S-60s or my EPI 70s. The EPIs actually sounded better with a little 25 WPC Dynaco SCA-50 driving them than they did with the Kenwood.

A lot depends on the fold back current limiting a power amp has in the driver stage , some amps have so much they sound like they have an audio compressor built in .

Other amps don't work well with some speakers , because the counter emf that the speaker crossovers develop interferes with the feed back loop of the amp .

Just looked at the fold back circuit in the Kenwood and it has the most limiting i have ever seen with a compound darlington transistors instead of a single transistor .

Not surprising results.
Despite the seeming Awe that Kenwoodie and Realistic seem to generate 'here'.
Those were regarded as Kmart "brands" back then.

Don't know much about your Kenwood but sounds like it could be sick. Every amp/receiver I've ever had did not have trouble with 6 ohm speakers. Unless you get it serviced, you will never know. 75 watts/ch into 86dB speaks would never do for me anyway. I would need more power, not enough spl for me in that combo.

I bought a 100 wpc Kenwood receiver (don't remember model #) at an estate sale, hooked it up to my Vandy's, found that it lacked the grunt to power the bottom end, sold it. Other than the bass, the Kenwood sounded fine.

Gibsonian said:

Don't know much about your Kenwood but sounds like it could be sick. Every amp/receiver I've ever had did not have trouble with 6 ohm speakers. Unless you get it serviced, you will never know. 75 watts/ch into 86dB speaks would never do for me anyway. I would need more power, not enough spl for me in that combo.

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It ran Infinity Qe's without any trouble, slightly more efficient but also 4ohm minimum speakers.

bare said:

Not surprising results.
Despite the seeming Awe that Kenwoodie and Realistic seem to generate 'here'.
Those were regarded as Kmart "brands" back then.

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Over here in the UK, Kenwood had that awkward association with kitchen appliances, so were not thought of as highly as they should have been. As for Realistic, very much bottom of the pile - not serious contenders.

I only speak for my personal impression of late '70's UK hi-fi buyers.

Kenwood, along with its relative Accuphase, made the best tuners:

http://www.fmtunerinfo.com/shootouts.html

The Kenwood Supremes are hardly KMart quality.

It sounds as though the Kenwood may need servicing.

Qes never seemed hard to drive to me. I remember driving mine with a Soundesign all in one that really did come from Kmart.

bare said:

Not surprising results.
Despite the seeming Awe that Kenwoodie and Realistic seem to generate 'here'.
Those were regarded as Kmart "brands" back then.

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I noticed your similar comment in the other thread. Perhaps if you started your own thread we could all debate the quality of Kenwood and Realistic without derailing other people's threads.

While bare seems to be snobbish about this stuff, if he can back it up in double blind testing then we need to STFU. I'm sure someone here can arrange it.

Some Realistics are really junk and I mean even "back then". And then they have their good models. I have never seen an old Kenwood that was junk. Of course when we got to the BPC there was, but not in the good old days. I cannot say I am familiar with all their models/lines.

Main thing to do if there is a major difference in the sound of two amps is to throw a 1,000 Hz square wave through them and looks see what it looks like on a scope. You can tell if it lacks lows or highs, or mids, or whatever. It does not tell you anything about distortion, or damping factor, but there are other tests you can do for that, even DIY with equipment that is not all that expensive. Of course if you want numbers traceable back to the NBS that costs a little more. But alot of surplus stuff can give you a damngood idea how things are running.

When you switch amps and run them at flat response loudness and filters all off, they should sound VERY close. If not, I get suspicious and tend to investigate.

Hey now Jurb...thems fightin words. Kenwood put out some good stuff in the late 80s BPC era. I would call them BPG (black pastic gems). My TOTL krv-127r, made in 1988-89 is a good example of that. 130wpc, 0.008 THD, 100db SNR, even has MM and MC phono selector. Sure its ugly as hell, but sounds great and drives my 89db Infinitys (rated 8ohms, but measure closer to 6) with clear, wide, deep, transient authority.

In the early 2000s, I purchased a used Kenwood integrated, made in the mid-late 90s, rated at 100wpc (forget model number). It couldnt hold a candle to my ugly, all button, krv-127. The integrated Kenny died an undignified death and went in the recycle heap. Good riddance. That Kenwood was truly BPC, despite its pleasing aesthetics and features.

Up until about 1990, Kenwoods amps were still decent. At least the higher end models were anyways. But I wouldnt buy one made any later than that.

Had a setup - Polk Monitor 10s, and a Kenwood 25watt per channel amp (70's). It wasn't powerful, but it sounded pretty darn good. Swapped the amp out for a more recent (90's) Sony '100watt' amp. More powerful, but no soul whatsoever. Sounded awful, actually.

nasadowsk said:

Had a setup - Polk Monitor 10s, and a Kenwood 25watt per channel amp (70's). It wasn't powerful, but it sounded pretty darn good. Swapped the amp out for a more recent (90's) Sony '100watt' amp. More powerful, but no soul whatsoever. Sounded awful, actually.

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I sold "everyday" consumer grade audio gear in the mid 90s... Sony, Pioneer, Yamaha, Technics, etc. Sony and Pioneer amps always sounded the most bland to me during this period. Yamaha sounded the best in our lineup, followed by Denon, then Technics (which had more "grunt" to them). Thats my 2c anyways. Stangely, we didnt carry Kenwood.

I would say your Kenwood amp is malfunctioning or your set up isn't correct (like improper speaker phasing). Just about any ordinary amp with over 35 wpc from all the popular brands of the 70's including Realistic should produce very pleasing sound. Of course some are better than others but not one should qualify as "utter fail".

The Kenwood sounded super-good...

...with every other set of speakers I tried it with.

Focal Daline 3's, Infinity QE's, Infinity RS-2000s, DCM CX-27s.

A video of it with the RS-2000s. Even through my crappy cell phone camera it sounds pretty solid here. Much better in person, obviously.

Big no on the Mirages though. It got louder when you cranked the knob, but never seemed to have life. Just dull and muffled.

I would chalk it up to synergy. For any one of a million undefinable reasons, some gear just works better with other gear.

I have had similar experiences using gear that I know is in perfectly good working order yet sounds like crap when paired with another piece of gear. I doubt its an indicator of a piece of gear needing repair.

My Dahlquist DQ10's never sounded as good as they should until I powered them with a Sony STR 7800SD. I tried them with a Yamaha CR2040, Yamaha C4/M4, Luxman C02/M02, Carver TFM 35 and just never warmed up to them until the Sony.

I have a pair of Mirage M790i that are absolutely stunning when powered by the CR2040, not so much with the Luxman, Carver or Sony.

My Carver Amazings pair very well with the TFM 35, not so good with the Yamaha or Luxman gear.

YMMV

The lesser amp appears to be the greater amp here. New pecking order?

battradio said:

A lot depends on the fold back current limiting a power amp has in the driver stage , some amps have so much they sound like they have an audio compressor built in .

.

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Improper use of the word "foldback". It is meant to mean a system of current limiting for a power supply that is based on a calculated level of current reducing the voltage so that current is lowered to the set point. In current this is linear, also it is intentional.

The inherent loss of transformers and such, even power supplies, is not necessarily foldback current limiting. It is not linear and things do burn up sometimes.

The only foldback current limiting possible as far as I know is the ferroresonant transformer. They were used in Zenith and a few other brand TVs back when they were built well. It provided a "natural" regulation and put out almost square waves to the rectifiers which needed less filtering.