Carver M-1.5t Review (Vintage Amp)

[capslock]

And here's a (actually two) Yamaha C-2010 from the late 1970s with 15 MHz TO3-transistors. The first one in that thread still had all its original caps. One driver transistor in one channel was broken which resulted in somewhat degraded performance in that channel until user scope fixed it for a friend. Further down, he bought a defective one for himself that somewhat had fixed using slow and possible counterfeit Moterola TO-3, some of which had blown again.

Yamaha CA-2010 Vintage Verstärker

That amp could be switched between class AB and class A. Note that class A does nothing but increase hum.

 

[iraweiss]

Try as I might I have been unable, so far, to find a review of this amp but I did find a review of the Carver receiver and here is the link: https://worldradiohistory.com/Archi...iFI-Stereo/80s/HiFi-Stereo-Review-1984-04.pdf

It's on page 22. They were getting distortion under .005 up to 100 wpc.

Unfortunately the scanned review of this receiver from Audio Magazine had the pages cut out...

 

[BeepPeep_61]

Good evening everyone,
The Italian Audio Review magazine in September 1982 had made a proof of the Carver M 1.5, I scanned the test to make you a comparison regarding the output power depending on the load, the frequency response, damping factor and SLEW Rate on 8 ohms. At the time, distortion was measured in the Tritim mode (distortion of dynamic intermodulation), on resistive loads, inductive and concealed.
I hope it is an interesting initiative, unfortunately the article is only in Italian.

 

[JayGilb]

Try as I might I have been unable, so far, to find a review of this amp but I did find a review of the Carver receiver and here is the link: https://worldradiohistory.com/Archi...iFI-Stereo/80s/HiFi-Stereo-Review-1984-04.pdf

It's on page 22. They were getting distortion under .005 up to 100 wpc.

Unfortunately the scanned review of this receiver from Audio Magazine had the pages cut out...

Thanks for the link. I love the talk of "The Digital Revolution".

From the review:
The distortion ratings of the Carver receiver's amplifier section proved to be quite conservative. With both channels
driving 8 -ohm loads, the distortion was
less than 0.005 per cent from 1 to more
than 100 watts output, reaching only 0.01
per cent at 150 watts. With 4 -ohm loads,
the distortion was 0.007 to 0.01 per cent between 1 and 90 watts, rising to about 0.03 per cent in the 150- to 200 -watt range. With 2 -ohm loads, the distortion
was 0.01 to 0.02 per cent up to 30 watts,
reaching 0.1 per cent in the 200- to 250 -
watt range and 1.74 per cent at 300 watts. Because of the rapid internal heating,
high -power measurements at 2 ohms had
to be made quickly, with only one channel driven. Nevertheless, the receiver suffered no ill effects from the abuse it received during our tests. Measured at the rated 130 watts or
less into 8 -ohm loads, distortion was between 0.003 and 0.01 per cent from 20 to
4,000 Hz, increasing to about 0.025 per
cent at 20,000 Hz. The amplifier section
was stable with complex reactive simulated -loudspeaker loads, but it showed
the typical overshoot and ringing on
high -frequency square -wave signals. I

 

[phoenixdogfan]

DH-220 claimed less than 0.02% THD which is better than this Carver by far from a measurement perspective. As you state, some of the Japanese units were at much better levels than that. All, though, are better than this Carver.

I currently use, among other amps, Benchmark AHB2s in both stereo and mono configurations. Nothing is close measurement wise, but I will not claim I can hear the difference between them and the other amps I have!!!

I love seeing these vintage pieces measured, though, and try for my amusement to see if they match in any way my memories of how I thought they sounded. I think this period was at the end of there being much legitimacy to impressions of amplifiers having a distinct "sound" and that was more from limitations of the technology and the resulting interactions with various speaker loads than any great magic of the designs themselves.

.02 is around 75 db sinad, so not great by today's standards, but not terrible either. ASR average is 79. 75 put it on a par with the Crowns, Outlaws, Sonnances, and any number of AVRs which people happily use today. And the Hafler DH200-220 was birthed in an era where the edge of the art format was vinyl playback with its 10 bit resolution, (60 db sinad) at best. It was more than adequate to the task in its day.

 

[SimpleTheater]

Try as I might I have been unable, so far, to find a review of this amp but I did find a review of the Carver receiver and here is the link: https://worldradiohistory.com/Archi...iFI-Stereo/80s/HiFi-Stereo-Review-1984-04.pdf

It's on page 22. They were getting distortion under .005 up to 100 wpc.

Unfortunately the scanned review of this receiver from Audio Magazine had the pages cut out...

This old magazine was a joy to look through. Cigarette ads and then I saw this short snippet on Sheffield Lab selling t-shirts "Stop the Digital Madness". Sheffield Lab is about 1/2 hour from my home, I may have to pay them a visit and see if they have any t-shirts hanging around in an old storage bin.

 

[KEFCarver]

View attachment 187193
Complicated, but leaning toward a honest disclaimer. Is this a Carver thing, an actual “standard” defining dynamic power, or something else (a 350 / 600W “short-term / long-term”continuous power)? I assume the measured 206W @8Ohm is in relation to the 350W spec, not the 600W…

Edit: when Amir says “it switches to higher power supply voltage”. Isn’t it the other way around? Switching from a high voltage (600W), to a lower one (350W)… which may contribute to the higher distortion.

I think Bob Carver explains a little bit about how the magnetic field p/s works in the beginning of the video. He (was) is quite the showman:

 

[KEFCarver]

This old magazine was a joy to look through. Cigarette ads and then I saw this short snippet on Sheffield Lab selling t-shirts "Stop the Digital Madness". Sheffield Lab is about 1/2 hour from my home, I may have to pay them a visit and see if they have any t-shirts hanging around in an old storage bin.

I had one of those T-shirts!

 

[phoenixdogfan]

I think Bob Carver explains a little bit about how the magnetic field p/s works in the beginning of the video. He (was) is quite the showman:

OMG, he's got the porno mustache from the '70's!

 

[DWPress]

I had one of these I purchased lightly used in the early 90's back when my speakers still had passive XOs but was playing with bi-amping. I didn't enjoy the sound as much as the previous Caver integrated HR-752 (with Sonic Holography!) and replaced it with a NAD 2200PE which I did like and ended up getting 2 more for bass and sub duty. Still have the HR-752 in storage and just looked at the manual in my file cabinet which had the sales receipt in it - I paid $467 for it in 1992!

 

[Ken1951]

Ok, I’ll run some 555 measurements next week. I still have the original power supply caps in there, so if time permits, I’ll do a before and after.

Look forward to this, as my 555 seems to doing fine. Runs my Paradigm S8s. Was bought new ages ago to power a pair of Magnepan MGIIBs

 

[amirm]

Try as I might I have been unable, so far, to find a review of this amp but I did find a review of the Carver receiver and here is the link: https://worldradiohistory.com/Archi...iFI-Stereo/80s/HiFi-Stereo-Review-1984-04.pdf

It's on page 22. They were getting distortion under .005 up to 100 wpc.

I own that receiver! I don't know where it is at the moment though but one day I will find and measure it.

The thing was very susceptible to mains noise. Every time our electric cooktop would cycle on and off, I would hear a nasty static. I contacted Carver and they said it was "normal." That the triac would misfire causing that. Or something to that regard.

 

[DonR]

I own that receiver! I don't know where it is at the moment though but one day I will find and measure it.

The thing was very susceptible to mains noise. Every time our electric cooktop would cycle on and off, I would hear a nasty static. I contacted Carver and they said it was "normal." That the triac would misfire causing that. Or something to that regard.

Sounds like you could use a PS Audio PowerPlant for it.

 

[amirm]

Sounds like you could use a PS Audio PowerPlant for it.

I knew someone was going there.

 

[Xyrium]

Yeah, no empathy or soft spot for vintage gear here, unless it's a monstrous Krell or eloquent Accuphase. Just sayin'

Looks like they sent that "magnetic field" straight to the outputs with all that noise.

Off with the panther's head!

 

[Chrispy]

Would be interesting to see this amp refurbished and re-measured. Or more reviews of 40-50 year old amps.....

 

[amirm]

I should mention that peaking through the heatsink shows a very clean amp. So it was well taken care of.

 

[rdenney]

Yeah, no empathy or soft spot for vintage gear here, unless it's a monstrous Krell or eloquent Accuphase. Just sayin'

Looks like they sent that "magnetic field" straight to the outputs with all that noise.

Off with the panther's head!

Amir gave a pretty good review and a recommendation for an Apt Holman preamp, and that's about as vintage as it gets for most of us. But that preamp had been refurbished thoroughly.

I tend to agree with those who think something is amiss with this Carver amp, especially given that some capacitors have been replaced with no hint of having made adjustments. (And I really make no complaint--I would replace caps without making those adjustments, too, if the amp sounded good to me. But then I wouldn't be measuring it with an AP analyzer, either.) My experience of looking at reviews with measurements has also been that Carver stuff (at least Phase Linear, Carver Corporation and Sunfire stuff) is well-documented and specified performance is attained as delivered new. On the other hand, one would have little basis to assume that this amp's sub-speced performance is anomalous in the company of other 35-40-year-old examples.

(I own a Carver PM-300 commercial amp and a Carver TX-11a tuner, both of which do what I want them to do.)

Rick "impressed by Miss Holographic" Denney

 

[Blumlein 88]

Yeah, no empathy or soft spot for vintage gear here, unless it's a monstrous Krell or eloquent Accuphase. Just sayin'

Looks like they sent that "magnetic field" straight to the outputs with all that noise.

Off with the panther's head!

Again the classic Krell KSA series only claimed .1% thd. or about -60 db.

Classe DR series amps only claimed .1% thd.

Mark Levinson no. 23.4 .1% thd and .2% into 4 ohm loads.

The earlier ML series specc'd .2% thd.

Accuphase claimed .03% or roughly -70 db.

Spectral claimed .01% or -80 db which is a little better.

 

[Xyrium]

Man, I forgot about Spectral.

Yes, a bit rough on them, but the marketing sliminess just gets to me. Magnetic Field....yeah, because there's a transformer in it? Come on. Those cheap speaker and RCA conns in the back....the attached power cord. All looks like an amp, when new, is $500.

Of course, if it had a pair of VU meters on the front, I'd give it a golfing panther, just due to effort.