Carver M-1.5t Review (Vintage Amp)

[ta240]

The 50/80 V Caps were replaced

Aren't there other smaller electrolytic capacitors elsewhere in the circuit that would be way out of spec by this point too?

 

[Angsty]

I have a Proton D1200 on the shelf but it is very much not restored. I think one of the VU meter lights is out.

I'm sure that if you wanted to send it out into the world to be loved again, there are a few members here that would be happy to line your pockets for it.

I had a Proton AA-1150 about 15 years ago that I sold; I loved the look of it but it had sonic and power limitations that I could not live with when I upgraded my speakers. There is a cottage industry out there now for restoring and improving those amps.

 

[Cougar]

As the owner of a Carver 900 receiver (in my youth) I was always disappointed in the amp. It was rated at 90 watts per channel. Yet my previous receiver, a Technics SA-410, rated at 45 watts per channel, could push my speakers to much higher levels. I felt ripped off and never bought another Carver product.

I had this same receiver, but my experience was different. I bought it off craigslist just to see how it would work for a back patio system. It actually did very well with some (dont laugh) Kenwood KL-999X speakers. Sound was above average but loud enough for backyard gatherings. I got it for the tuner in it which was pretty good to my surprise. These is probably due to the high effecient Kenwoods but for that application, it worked out well.

Now for the not so good. I tried this receiver in my main system and it did sound ok but surprised me it did better with the Kenwood speakers than my Paradigm Esprits (Originals) that I had at the time due to my Carver Amazings Silvers being down due to one of the ribbons not working at that time. Just sound more closed in and just not much life to the sound. Was better with Kenwoods, just Weird!

 

[Cougar]

I'd love to see the test results from the Adcom GFA555 to compare. I have a soft spot for Nelson Pass due to his generosity towards the DIY community and am curious how the GFA holds up in a battle of 40-year old designs. I spent hours in my youth drooling over both Carver (TFMs) and Adcom amps. They, and to a lesser extent, H/K and Bryston, were the high-end lines sold by the big electronics stores when I was in high school.

I had the Adcom GFA-555II and the Adcom GFA-545II at one point, the 545II sound better than the 555II in my system. Now the Adcom 565 mono blocks were really nice. I heard them in a friends ystem and was really impressed how good they sound.

 

[MaxBuck]

I had the Adcom GFA-555II and the Adcom GFA-545II at one point, the 545II sound better than the 555II in my system. Now the Adcom 565 mono blocks were really nice. I heard them in a friends ystem and was really impressed how good they sound.

Cool story.

 

[jcarrico]

We've been through this before. There's plenty of vintage amplifiers that are not only rated at least 2 orders of magnitude lower THD than those examples, but they are also conservative with those ratings.

Also, the THD numbers for properly compliant vintage gear are across the power range (from 250mW to rated power) and frequency bandwidth (20Hz-20kHz), something all these ASR pole sitters are not.

Would you be willing to name some of those amps? Or just vintage amps that you recommend?

 

[traderitch]

The 50/80 V Caps were replaced

Stock M-1.5t

 

[traderitch]

Upgraded M-1.5t
(circuits and concepts makes a board for the high rail caps - unobtainable)

 

[davidc]

Get hold of a pair of Kenwood LO-7M/mk2s or a Pioneer SA-9800 integrated. RETs/diffused emitter/LAPTs in another guise (Sanken and later Toshiba). The Fujitsu RETs were amazing when it came to high frequency, high power linearity when implemented well.

I've got a refubished SA-9800 that I'm ready to put up on eBay. To think they are selling for over twice what I paid for it in 1980!

 

[davidc]

Wonder how much deterioration due to age affected the measurements?

Huge amounts is my guess. The amp didn't even produce the rated power, and this was back when the FTC strictly regulated stereo power amp ratings to RMS, at a stated distortion, both channels driven, 20-20kHz. Not the BS ratings of today.

 

[davidc]

I was a live and well in the '80s, (maybe more so than today). In the day I never gave any serious though to a Caver amp; I was always suspicious of them you might say.

OTOH, through the '80s and '90s I was running a Phase Linear 400 amp, a very well-measuring amp for the day. At the time I was very confident that I had a amp that was as good as any. It took me 20 year to understand that the PL 400 was a truly hideous sounding amp. I'd had the PS capacitors replace at one point but that help. It was amps like the 'Phase' that gave solid state a bad rep for many audiophiles. Not only were the highs shrill & glassy but detail and transparency were totally lacking; "opaque" would be an appropriate adjective.

That's only because you didn't have the 700! lol

 

[davidc]

Being a kid at the time, I never measured anything. What I can say is I never had to put my Technics SA-410 past half way on the volume, but when I put the Carver 900 into my system, I had to crank it to three quarters to max to achieve my normal listening volume.

By the time Carver has started mass producing stuff like the receivers, he wasn't using his "magnetic field" power supply. No comparison is possible.

 

[davidc]

It actually states that the owner replaced them "The owner has replaced the capacitors in this unit." Were they professionally done and was it an 'upgrade' or a 'replacement'? Those seem like different things that could affect the performance; especially since in the audiophile world upgrades often take things out of original spec.

Not knowing the quality and full extent of the work makes it a bit hard to judge. It is a bit like driving a 35 year old car and judging the company that built it rather than the people that maintained it.

So true. There is a website dedicated to Carver type stuff. There are several members of the site who complettely refurbish the units for $3-400. They do much more than "replace the caps". A 40 yr old unit is going to have a lot wrong with it that affects measurements. We have no idea what was done to this amp.

Think of a 40 yr old car that has has the tires replaced. That's what I feel about this review.

 

[davidc]

The photo log of rack mounting that thing would be hilarious. Step 1: WTF? Step 2: locate drill.

Yes, I am surprised Amir didn't catch this. Carver had a whole separate line of Pro amps that were rack mountable. Back in the 80's-90's, Carver pro amps were the absolute "go to" amp for concerts by rock groups. Huge, huge amounts of power, very light weight, and protection circuits that were far more sophisticated that what was available in consumer equipment.

 

[davidc]

The m1.0t has a power switch on the back.

Actually no. But...you may seen one modified. There are a lot out there.

 

[davidc]

I do feel those results seems a little off. I see at least two adjustment potentiometers in this box, quite possibly a couple more. Sometime Bias, balance or some key voltages.. The very least of maintenance on a 40 Year old units is to be able to measure a few test points with a Scope and adjust to specs. Just swapping all caps and putting the lid back on without any measurments, honestly the chances of having it back to specs are slim. It would be interresting to know what he really did.
View attachment 187287

Agreed. The instruction and service manuals are readily available on https://thecarversite.com/

https://thecarversite.com/manuals/mandir/Carver%20M-1.0t%20Service%20Manual.pdf

https://thecarversite.com/manuals/mandir/Carver%20M-1.0t%20owner%20manual.pdf

https://thecarversite.com/manuals/specsheets/files/M-1.0t%20specsheet.pdf

 

[davidc]

Aren't there other smaller electrolytic capacitors elsewhere in the circuit that would be way out of spec by this point too?

Normally, when are refurb is done on these units, ALL electrolytic caps are replaced, as well as all "flame" resistors. All contact points are cleaned, circuit boards are inspected all service manual alignments and updates are performed.

 

[JayGilb]

Stock M-1.5t

That's not a stock unit. The 50/80v rail caps were of a 2 in 1 variety that soon became impossible to source and Carver supplied a separate pcb that
held the 4 replacement caps for the 50/80v rails. The unit in the image has had those caps replaced.

Edit: I checked my old capacitor box and was able to find an original 2 in 1 caps from a TFM 45 I once worked on.

 

[davidc]

That's not a stock unit. The 50/80v rail caps were of a 2 in 1 variety that soon became impossible to source and Carver supplied a separate pcb that
held the 4 replacement caps for the 50/80v rails. The unit in the image has had those caps replaced.

Edit: I checked my old capacitor box and was able to find an original 2 in 1 caps from a TFM 45 I once worked on.
View attachment 195926 View attachment 195928

That's cool. For whatever reason, I went on a Carver buying spree a couple of years ago. (Bob Carver and Brian Cheney were two of my favorite audio designers. They weren't afraid of challenging the BS state of the art golden ears).

I bought a new AVR, a Denon 4700, primarily from reviews here, and run Carver amps to power all the speakers. All the amps have been "fixed" if anything wasn't working right, including all electrolytic caps replaced, all 'flame" resistors, everything cleaned well (connections, switches) PCB's inspected for bad soldering, updates done, and certain mods that have shown to be useful). I have mostly the "pro" equipment as it was less expensive used and in certain cases has most robust build and fans and extra output transistors. I have a PM-1.5a, PM-2.0, PM-1200 and PM-1205. I would buy a TX-11b tuner (one of the best ever made) if I ever listened to FM (actually, probably not, if I listened to FM I'd get something with HD Radio). It's more power than I'll ever need and I think they sound great. It's true that the "magnetic field amps" can put out a buzz sometimes that comes and goes, but, you can never really hear it because of masking. I'm happy with it.

 

[JayGilb]

That's cool. For whatever reason, I went on a Carver buying spree a couple of years ago. (Bob Carver and Brian Cheney were two of my favorite audio designers. They weren't afraid of challenging the BS state of the art golden ears).

I bought a new AVR, a Denon 4700, primarily from reviews here, and run Carver amps to power all the speakers. All the amps have been "fixed" if anything wasn't working right, including all electrolytic caps replaced, all 'flame" resistors, everything cleaned well (connections, switches) PCB's inspected for bad soldering, updates done, and certain mods that have shown to be useful). I have mostly the "pro" equipment as it was less expensive used and in certain cases has most robust build and fans and extra output transistors. I have a PM-1.5a, PM-2.0, PM-1200 and PM-1205. I would buy a TX-11b tuner (one of the best ever made) if I ever listened to FM (actually, probably not, if I listened to FM I'd get something with HD Radio). It's more power than I'll ever need and I think they sound great. It's true that the "magnetic field amps" can put out a buzz sometimes that comes and goes, but, you can never really hear it because of masking. I'm happy with it.

I too have a large rack of PM series gear. Two PM-1200s, a PM-900 and a PM-600 that I use in a quad-amped configuration.
Yes, the transformers like to hum a little, but no big deal in my opinion.

Very dynamic, powerful amps with a good deal of headroom and like you, am happy with my sound.