Carver M-1.5t Review (Vintage Amp)

[KEFCarver]

I have had 20 year old Bryston gear that tests as new after a trip to their shop. I did have a couple of switches replaced but not interior electronics. The models were BP-25DA and 4B-ST. I also had a BP-1.5 whose “ground points were tightened up”. I buy used Bryston gear because their shop can repair virtually any component that they have made.

Bryston is a great company from my little experience in dealing with them, and their BP-2LP amp of which I own two- is a nice little power amp.

 

[livinon2wheels]

It comes as quite a shock to me this amplifier reviewed so badly. I suspect that it is not representative of how these amps perform when everything is working correctly. I have owned a few of these myself and when hooked to decent speakers and source material they are quite the powerhouse. That is a subjective thing for sure and I have never measured power other than to put a db meter on the main speakers when I was driving it just shy of clipping and in my 15x18 listening room could achieve 115 db levels. Of course I don't know what the history of the amp is that you tested Amir, but if its as old as you say and has not been restored with new caps and so on I would say that is pretty good performance for an unrestored 40 year old amplifier. It surely says that the amp needs attention from a qualified tech. And one of those for these class H amps are few and far between in my experience. I would love to see what a restored 1.5T would do.

 

[KEFCarver]

It comes as quite a shock to me this amplifier reviewed so badly. I suspect that it is not representative of how these amps perform when everything is working correctly. I have owned a few of these myself and when hooked to decent speakers and source material they are quite the powerhouse. That is a subjective thing for sure and I have never measured power other than to put a db meter on the main speakers when I was driving it just shy of clipping and in my 15x18 listening room could achieve 115 db levels. Of course I don't know what the history of the amp is that you tested Amir, but if its as old as you say and has not been restored with new caps and so on I would say that is pretty good performance for an unrestored 40 year old amplifier. It surely says that the amp needs attention from a qualified tech. And one of those for these class H amps are few and far between in my experience. I would love to see what a restored 1.5T would do.

I finished testing two m1.5t's last week for my small youtube channel. THey were from the same owner, and one had been returned to Carver for a warranty repair and the other was all original. While there was some noise on the original one, it was not audible by me. They both sounded fine during my listening tests, though I only hit a 95dB spl in my room- which was pretty loud. There were some mixed results in the measured performance of the two. I believe the one Amir reviewed had been recapped.

 

[Theta]

I finished testing two m1.5t's last week for my small youtube channel. THey were from the same owner, and one had been returned to Carver for a warranty repair and the other was all original. While there was some noise on the original one, it was not audible by me. They both sounded fine during my listening tests, though I only hit a 95dB spl in my room- which was pretty loud. There were some mixed results in the measured performance of the two. I believe the one Amir reviewed had been recapped.

I have 6 vintage Carver amplifiers, never recapped or serviced, all working fine and sounding good. That is my review.

 

[KEFCarver]

I have 6 vintage Carver amplifiers, never recapped or serviced, all working fine and sounding good. That is my review.

The fact that they are are working well and sound good to you is fine, but not really much a review. The main focus here at ASR is how things measure up the their specs. Practically, there is not going to be any real difference in sound from an amp that may have a THD of .1% vs one that has a THD of .001%, all things equal. As for your Carver gear, if they happen to be M400/a/t cubes that are powered on in most of the time, or used a lot, you may want to consider having them recapped as those do go bad and can cause more expensive problems down the road.

 

[perdido34]

I finished testing two m1.5t's last week for my small youtube channel. THey were from the same owner, and one had been returned to Carver for a warranty repair and the other was all original. While there was some noise on the original one, it was not audible by me. They both sounded fine during my listening tests, though I only hit a 95dB spl in my room- which was pretty loud. There were some mixed results in the measured performance of the two. I believe the one Amir reviewed had been recapped.

Can you post a link to your YouTube review?

 

[Theta]

The fact that they are are working well and sound good to you is fine, but not really much a review. The main focus here at ASR is how things measure up the their specs. Practically, there is not going to be any real difference in sound from an amp that may have a THD of .1% vs one that has a THD of .001%, all things equal. As for your Carver gear, if they happen to be M400/a/t cubes that are powered on in most of the time, or used a lot, you may want to consider having them recapped as those do go bad and can cause more expensive problems down the road.

Thanks for the tip on the M400, fortunately I don't own one of those, Carver made over 100 different power amps. Most Carver amps are class H, a much neglected fact. The best amp according to Amir and other is the Benchmark AHB2, also class H.
I have a tri-amped system.
According to some tech expert on this site (I don't recall their names), If I replaced my Carvers by one or more AHB2, I would probably not hear the difference, actually my carvers being more twice the power of the AHB2 might even be better. The diference is €600 against €11000.
Regardless of my lack tech knowledge, I just just though this information might be usefull to someone on this forum.

 

[KEFCarver]

Can you post a link to your YouTube review?

Thanks for your interest. The channel is Vintage Audio Review. I "only" post one video/review each week, and am trying to post the oldest ones first when I can. By that I mean that I do all of testing and video work and put it into a folder and when it is that device's "turn", I start editing the information in the folder into a video. Since I just finished the Carver M1.5t work, it will probably be at least 1-2months before it is released. They belong to a friend of mine and he plans on posting them on Craigslist, and having a video on them helps (usually)- so I may move this up a bit. I don't have any arrangement where I get any "kickback" when he sells something, I should point out- I get a bunch of gear to test from him....

 

[KEFCarver]

Thanks for the tip on the M400, fortunately I don't own one of those, Carver made over 100 different power amps. Most Carver amps are class H, a much neglected fact. The best amp according to Amir and other is the Benchmark AHB2, also class H.
I have a tri-amped system.
According to some tech expert on this site (I don't recall their names), If I replaced my Carvers by one or more AHB2, I would probably not hear the difference, actually my carvers being more twice the power of the AHB2 might even be better. The diference is €600 against €11000.
Regardless of my lack tech knowledge, I just just though this information might be usefull to someone on this forum.

I have not had any benchmark gear to test/listen to, but it looks like pretty good stuff and they have some nice technical articles on their website. I would agree that you would most likely not hear any difference between the Benchmark and Carver amps, aside from hum/hiss with no signal applied (inputs terminated in shorts) and your ear fairly close to your speakers. This also assumes that you are not trying to rattle pictures off your walls- possibly reaching the end of the amp's non clipping region. Soundcraftsmen also used a class H design, but it is implemented differently and their gear is heavier. I own two m400a and recapped them- one took me 5times to get it back together correctly- they are a real PITA, and the M1.5t appears to be a pain to recap as well.

 

[Theta]

I have not had any benchmark gear to test/listen to, but it looks like pretty good stuff and they have some nice technical articles on their website. I would agree that you would most likely not hear any difference between the Benchmark and Carver amps, aside from hum/hiss with no signal applied (inputs terminated in shorts) and your ear fairly close to your speakers. This also assumes that you are not trying to rattle pictures off your walls- possibly reaching the end of the amp's non clipping region. Soundcraftsmen also used a class H design, but it is implemented differently and their gear is heavier. I own two m400a and recapped them- one took me 5times to get it back together correctly- they are a real PITA, and the M1.5t appears to be a pain to recap as well.

My go to Carver is the TFM-35s, never a problem, sound wise, I guess I am biased, I own a few class A's, lots of class AB, some mosfets, no reason to try a class D yet.

 

[RetreadTech]

The great thing about the Carver amp was it was easy to repair. 1 shorted output transistor and 1 blown triac (acting as the shutdown circuit) was all it usually needed. The average run of the mill receiver/amps would require a handful of parts if the outputs shorted.

 

[KEFCarver]

The great thing about the Carver amp was it was easy to repair. 1 shorted output transistor and 1 blown triac (acting as the shutdown circuit) was all it usually needed. The average run of the mill receiver/amps would require a handful of parts if the outputs shorted.

I would have to respectfully disagree with you if you are saying that the m1.5t is easy to repair. Just blowing 1 output transistor and nothing else is unusual and would be an easy repair on the that amp, but if you want to replace all the electrolytic caps or had other parts go bad that required removal of the other 3 boards that are connected together (soldered via connectors), you have to remove 20output transistors just to start. I think the M400 cubes may be easier to work on, and they are a bit of nightmare IMHO. For the most part I like Carver gear despite there sometimes poor serviceability.

 

[RetreadTech]

I would have to respectfully disagree with you if you are saying that the m1.5t is easy to repair. Just blowing 1 output transistor and nothing else is unusual and would be an easy repair on the that amp, but if you want to replace all the electrolytic caps or had other parts go bad that required removal of the other 3 boards that are connected together (soldered via connectors), you have to remove 20output transistors just to start. I think the M400 cubes may be easier to work on, and they are a bit of nightmare IMHO. For the most part I like Carver gear despite there sometimes poor serviceability.

Sure. Now. 40 some years ago, Carver had a great simple shutdown design. Most receiver/amps back in the day took out both outputs in a channel, and maybe parts in the driver stage. I worked on a few Yamaha receivers that the damage included pre- drivers, drivers, and outputs. And if you didn't check everything carefully, you risked the new outputs.

 

[Speedskater]

Countless early Carver amplifiers were destroyed by people trying to repair the amp's very unconventional power supply.

 

[HTHOOK]

In lieu of the 1.5, In 1988 I bought a pair of 1.0ts to use as stereo bridged mono blocks. They were first generation, lacking the bridged switches on the back panel, so the dealer performed an internal bridge that was nothing more than a small piece of speaker wire soldering both channels together (under “ the hood”)
Those amps configured in that way were ridiculously potent (1000 watts rms@8ohm) but back in the day, ignorance was bliss!
Before they went away on EBay, I got back in there and restored the channels to their original state.
……Been powered by Bob Carver since 1977….Phase 400 1988 those 1.0s and now HT transitioned with the Signature 400 5 channel. Together with The Velodyne HGS 18….a very sweet balance of power.

 

[KEFCarver]

Sure. Now. 40 some years ago, Carver had a great simple shutdown design. Most receiver/amps back in the day took out both outputs in a channel, and maybe parts in the driver stage. I worked on a few Yamaha receivers that the damage included pre- drivers, drivers, and outputs. And if you didn't check everything carefully, you risked the new outputs.

I really hate when you see burned resistors around the driver transistors (and burned driver transistors for that matter). Gotta have a variac!

 

[Theta]

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.
View attachment 366596

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.

If it's not broke don't fix it.