Carver M-1.5t Review (Vintage Amp)

[davidc]

So a 42 year old amp was measured… and the owner stated they changed the tires and the gas filter..
Seriously, this is like measuring the “performance” of a 1988 Z-28 with 250,000 miles that was sitting in the barn for 20 years, had new tires put on, a new gas filter, maybe an oil change (we don’t really know), with work done, or not done, by someone with no known qualifications to even work on cars, then detailed up to ”look pretty”.
Then was put on some machines to “measure” how well it was running…

Undoubtedly, even though it’s “measurements” might not look great, it would still run rings around a new, well measuring prius, (or even a well maintained 1988 Corolla) but the z-28 would still be waaaayyyy more fun.

But a 1988 Z28 is still a crappy car. All American cars of that era were crappy! lol

 

[davidc]

It would have been cool to see a properly restored M1.5t be tested. There is a whole cult following of Carver gear and a few individuals who specialize in restoring them.

TheCarversite!

Forum dedicated to Bob Carver, his products, and more

thecarversite.com

 

[KEFCarver]

I would not call the group of Carver Followers a "cult"- maybe fanboys- and they really defend Carver gear (most of it, anyway). I am sorta a Carver Fanboy, but have no problem "calling a spade a spade" when it comes to Carver gear that I test. My guess would be that a restored/upgraded M1.5t would still be (power supply) noisy but not objectionable and would be able to deliver more power that an original M1.5t.....

 

[davidc]

Agreed. I've just always been a fan of Carver because of his innovative designs in electronics and loudspeakers, and his no fear attitude towards designing things very unconventional

 

[JayGilb]

I would not call the group of Carver Followers a "cult"- maybe fanboys- and they really defend Carver gear (most of it, anyway). I am sorta a Carver Fanboy, but have no problem "calling a spade a spade" when it comes to Carver gear that I test. My guess would be that a restored/upgraded M1.5t would still be (power supply) noisy but not objectionable and would be able to deliver more power that an original M1.5t.....

Carver had some gems and some POS units. I have racks of Carver gear at home that I have brought back to life or just tuned back into spec and yes, they do have transformer hum and the lights dim when powered on, some pieces are difficult to repair, but I enjoy the sound and looks of that old 90s gear.

 

[KEFCarver]

Carver had some gems and some POS units. I have racks of Carver gear at home that I have brought back to life or just tuned back into spec and yes, they do have transformer hum and the lights dim when powered on, some pieces are difficult to repair, but I enjoy the sound and looks of that old 90s gear.

I have not noticed the light dimming at my house with my m400a's. Well, just one m400a, as the other one I am about to take apart for the 5th time to try to figure out why it is in protect mode following a cap replacement, which it worked fine for about an hour after the cap replacement. They are indeed a real pain to work on...But they are cute and sound great when working.

 

[andrewdrouin]

I've owned a Carver CUBE and a Carver M1.5t - both died within two years of me purchasing them :-( They look cool, but I am certainly not a fan of Carver unreliability...

 

[Willem]

Right now, I am listening to a refurbished Quad 405, a model that was first introduced in 1976. Admittedly it only delivers 2x100 watt rms at 8 Ohm, but the distortion is less than 0.01%.

 

[Angsty]

Right now, I am listening to a refurbished Quad 405, a model that was first introduced in 1976. Admittedly it only delivers 2x100 watt rms at 8 Ohm, but the distortion is less than 0.01%.

Just keep in mind that 0.01% distortion equates to about -80 dB or an effective number of bits (ENOB) of about 10.5 bits.

That’s far less than CD quality. It’s an older amp, so that’s probably pretty good for its time.

Today, one can find inexpensive 100W amps in excess of -100 dB THD.

 

[antcollinet]

Just keep in mind that 0.01% distortion equates to about -80 dB or an effective number of bits (ENOB) of about 10.5 bits.

Isn't 80dB and ENOB of 13?

And -80dB is better than most speakers, and in any case inaudible to almost everyone in real world listening conditions.

 

[Angsty]

Isn't 80dB and ENOB of 13?

And -80dB is better than most speakers, and in any case inaudible to almost everyone in real world listening conditions.

I used an online Analog Devices calculator and did not calculate the values from equations myself.

-80dB is likely good enough for real world listening - I just posit that it’s dated performance compared to current alternatives.

Edit: After further review of the AD calculator, I likely misused it. I’ll concede the ENOB of 13 bits without additional calculation on my part - it seems to make more sense anyway.

 

[EJ3]

Just keep in mind that 0.01% distortion equates to about -80 dB or an effective number of bits (ENOB) of about 10.5 bits.

That’s far less than CD quality. It’s an older amp, so that’s probably pretty good for its time.

Today, one can find inexpensive 100W amps in excess of -100 dB THD.

Angsty Don't forget that our even our old NAD 2200's had/have 95 SINAD and 19 bits of dynamic range through the LAB inputs, not to mention:

 

[Angsty]

Angsty Don't forget that our even our old NAD 2200's had/have 95 SINAD and 19 bits of dynamic range through the LAB inputs, not to mention:

I have not forgotten! I’m just admitting that a -80 dB THD amp is likely good enough for “real world listening”. I have no intention of going backward, but I would not bet on my ability to consistently differentiate between a -80 dB THD amp and a -95 dB one.

(Yes, pedants, I do know there is difference between THD, THD+N, and SINAD.)

 

[Mike70550]

I was bumming around on the shopgoodwill web site, and saw a M-1.5 there. (As of 4/28/2024) with four days left to bid For $200+.
its autographed by Bob Carver and Rita Helm. Its serial number is 0087.
My speakers would probably catch fire connected to it, if you all want to see the listing and the pictures@ https://shopgoodwill.com/item/197632457. Or just search for “Carver” on the shopgoodwill website.
Because it’s signed by Bob, I thought it deserved a better ending than Goodwill.
I tried, but can’t attach a picture here…
Mike

 

[restorer-john]

I was bumming around on the shopgoodwill web site, and saw a M-1.5 there. (As of 4/28/2024) with four days left to bid For $200+.
its autographed by Bob Carver and Rita Helm. Its serial number is 0087.
My speakers would probably catch fire connected to it, if you all want to see the listing and the pictures@ https://shopgoodwill.com/item/197632457. Or just search for “Carver” on the shopgoodwill website.
Because it’s signed by Bob, I thought it deserved a better ending than Goodwill.
I tried, but can’t attach a picture here…
Mike

Classic find!

Should be easy enough to remove the gold pen graffiti. *kidding*

 

[Ranster]

Just look at schematics from Kenwood, Onkyo, Sanyo, JVC, etc. from back then. Also, Ring Emitter Transistors achieved bandwidths that are no longer speified in today's top transistors. I recently bought a few vintage amps specifically to see if those transistors were that good and if modern transistors are maybe better than spec or as bad as their data sheets say they are. I will certainly measure the odd amp, but most need work on caps and switches before that.

Mostly, that is in the imagination. I have plenty of absolutely stock standard 40+ year old amplifiers that not only meet their specs, but exceed them.

What old stuff do you have that meets and exceed all specs.? I own some old stuff and almost all capacitors age with time. Especially electrolytic. THat being said I am curious as to what equipment I should be looking for thats vintage. Because now all the sudden I don’t like my carver m1.5t. Just kidding I don’t own it. Anyway, A lot of stuff has been fiddled with. A lot has not. I also know that bean counters interfere with design engineers and profit margins had to be met. I guess I’m asking is some of that good equipment even affordable to most people? If so please save me from buying something old that doesn’t measure well. NAMES I want names and models of equipment. I do know there were 10-12 thousand dollar amps being offered back then. Surely not those as we, me and most others, couldn’t afford those even today. I don’t want to buy a new AVR that’s crappy. Can’t afford the new good stuff and hearing how bad the affordable stuff is sucks sometimes because that’s all I can afford. Anyway sorry for the question mixed in with statements. My intentions are good and honest here. Also I looked for a list of stuff that is only recommended by @amirm am I missing it? Thanks for the help and future replies

 

[Ranster]

I'd be very curious to see what's going on with that residual switching noise.

I mean is the issue in this amp something that can be fixed? Instead of throwing away older gear…..

 

[Ranster]

For 1976 measurements of the then new 2x100 watt Quad 405 current dumping amplifier, see: http://www.meridian-audio.info/public/quad_405_test_reports[2314].pdf The later 405-2 and even more so the 1986 2x140 watt 606-2 improve on this even more. This goes to show that already at that time sonically perfect amplifiers were possible.

How much did the Meridian cost compared to the carver?

 

[restorer-john]

What old stuff do you have that meets and exceed all specs.? I own some old stuff and almost all capacitors age with time. Especially electrolytic.

Plenty of gear tests as new. I have an awful lot of HiFi, a collection you may find hard to comprehend the scale of. Suffice it to say, like everything, there's a lot of BS and opinions stated as facts that are far from it.

I've pulled NOS sealed stuff out of my storeroom that is over 30 years old and tests better than rated spec (because they were conservative in the first place). Right now, there is a 30kg, 1976 Pioneer SX-1250 on my lab bench being restored and repaired. It tests better than spec (amp/preamp section).

In case you think I'm making that up.

Why does everyone point the finger at electrolytics? Because everyone has seen a leaky cap, heard about leaky caps and knows they are easy enough to source and replace. And it makes them feel like they've "restored" something. They haven't.

Why stop at electrolytic capacitors? What about film, greencaps, ceramic and tantalum? Most resistors drift. So do fusible resistors (they are terrible). Diodes, zeners get noisy, transistors become leaky, noisy or low in gain. Pots wear, switches corrode/oxidize, CMOS switches break down, VFDs lose their emissive properties, transformers can break down etc. etc.

Capacitors are an easy target for weekend warriors. Mostly, they fix nothing and often (more than often) they make a mess and consign what was a perfectly/mostly functioning vintage product to the scrap heap.

Measure your gear, fault find and repair first! NO throwing a bag of capacitors at it to see what sticks. Then you have a functional baseline. If you cannot measure your gear, you have no business poking around inside it attempting to fix something you haven't quantified as being broken in the first place.

 

[Ranster]

This is all I know from the owner: "It had some caps replaced a couple of years ago, and is in good working condition." Once I get a hold of him, maybe he will explain more.

My whole concern is with owner submitted equipment. Many many old tinkerer has been inside of stuff. Case in point, I couldn’t figure out why one channel of my preamp sent more signal to the right than to the left. After looking around I found that the old owner had replaced a cap with different specs. It was very hard to spot but upon questioning he owned up to it. That being said I’m in for people not being lied to nor taken advantage of but….maybe test two of the design to be fair as comparison.