Carver Crimson 275 Review (Tube Amp)

[paulbottlehead]

So you basically bypassed the grounding resistor used in the amplifier?

This is how Carver says to measure the amp I order to not bypass that resistor. Load to speaker terminals, FFT ground to audio ground.

This was addressed in the previous review I posted already.

The sweeps I posted demonstrate what this current feedback is doing.

 

[sarumbear]

The amp blew its fuse while producing 60W at 1kHz, both channels driven. At while producing 15W at 20Hz, also both channels driven.

3A at 117VAC is around 360W.

So the amplifier efficiency was around 33% at 1kHz and less than 10% at 20kHz

PS. I am making simplification but they shouldn’t make much difference given the low efficiency values.

 

[SIY]

The negative speaker terminal in the 275 is not tied directly to ground/earth, so I made some comparisons with the negative tap floating vs. grounded. I suppose it's not appropriate to call it earth since there is no earth reference in the 275.

There's similar issues with most of the classic AR amps- they used the output transformer secondary to provide cathode feedback to the output tubes, so both Common and 8/16 were not grounded and a differential input for any analyzer is needed. So this isn't exactly unprecedented.

 

[Jmsent]

Fisher & Paykel had the worst reliability track record of any appliance company when I looked at their products for our kitchen remodel. No wonder given that statement!

I own one F & P product...a DCS stove. It's built like a tank and works great. It has no computers or timers. The only electronics are the spark ignitors. It's a good product, but the customer service, which was required due to damage during installation, was pretty lousy.

 

[solderdude]

Here are some quick sweeps I did on a test woofer with the negative speaker terminal floating and the negative speaker terminal connected to audio ground. These are on Carverfest 275s which are alleged to be different amplifiers, but we aren't really able to say why or how.
View attachment 179665
Above is with the negative terminal earthed.
View attachment 179668
And a floating negative.

Weird, the opposite of a possible desired effect is obtained. There is feedback coming from the output voltage + from the output current (which creates a voltage drop across the 0.1ohm R26. Less current (= higher impedance) should be less feedback voltage making the circuit less load dependent. The opposite is happening. Maybe the external shorting of the - to chassis (gnd) introduces some errors.
The schematics below clearly show the 'room effect reading' is a bunch of nonsense.

 

[SIY]

There's also no excuse in 2022 to use a cathode resistor in the phase splitter, then unbalance the plate resistors to make up for it.

 

[traderitch]

Good Morning, afternoon or evening:

I was really hoping this thread would tighten up with less negative sniping.
Graphs, measurements and true electrical circuit knowledge carry more intellectual weight than the drive by "this is a piece of garbage."

There are way too many posts mentioning the lack of response from Carver employees.

A few of the members mentioned their level of business acumen and experience.
Those individuals should know that a 'corporate response' is a well worded and measured release.
I don't know of any company that would respond once phrases such as class action, regulators, dangerous
are used in context of their product - without investigating the claims and having their council review the findings.

I would assume that the dealers would have the information/remedies first. This would allow them to reach out
to people that actually own their product.

So - let's be patient and wait for a response from a representative.

 

[jbhiller]

Hello ASR Forum! I'm a new poster here, but I have read copious reviews and posts over the last few years here and appreciate what ASR does. [That said, for full disclosure, I also put a ton of weight into how things sound; I don't care if a guitar amp tests that well--I want tone and features. Hifi is a bit similar and a bit different for me]. Getting my personal view out of the way....

I dropped in for a number of reasons.

1. First, I want to thank Amir and Paulbottlehead for their professionalism and courtesy. Paul dropped by my thread on Audiogon and was an absolute gentleman. I tore down the amp to confirm the presence of the Edcor OPT--to which Paul was ever so sweet and thankful. I didn't go further into the PT because I think I threw up in my mouth upon seeing that little guy.

2. I have nearly exclusively used this amp with super efficient loudspeakers (102dB), so before you or I call me an idiot for tweaking the amp (and also questioning its build quality early on, long before Amir's great work), I had no basis to even guess at its power output. If it could really put out 17w into an 8 ohm load, that's probably all that's needed to get my loudspeakers to sing.

3. I vote this amp not even worthy of ASR's voting system. It's despicable what the "Carver Corporation" has done in its marketing. I'm a lawyer by trade so I will say that there is just not enough evidence for me to find Bob culpable--at this juncture, based on what I've seen. I'll explain more below.

4. What the heck is going on with the lack of chassis grounding? I noticed it too and have been thinking about correcting it before Amir's review. That is totally inexcusable--note I'm a DIY hobbyist so keep in mind I'm not an authority on electrical safety, yet I do care about it and discharge caps when I go inside units.

5. Mine unit is clearly better built than Amir/Paul's unit--yet not by much.

6. The wiring to the output terminals makes me sad. Sad. Who would do such a thing? I've owned so much gear that I'm embarrassed to put out a number of units. I haven't seen anything like this since I took apart my JCPenny stereo in 1982. Note--my unit has nice heavy gauge wire running to the output terminals. What gives? This is inexcusable at this priceoint or any price where we are dealing with something that is supposed to be high fidelity.

7. The OPTs. Hmmmmm.... I have bought Edcors, Hammnonds and Lundhals. I had transformer hum (for OPT and PT) and talked with Malitz for a good bit on the phone about it. He said that they moved their sourcing of the transformers to another vendor and were having issues with some of them. Could it be that Bob Carver's original amp had better transformers and Malitz/Carver Corporation cheapened the whole design as an objective of making more money? I think that is a possibility.

8. Testing. It seems nearly indisputable that this thing as sold is not what the Company markets. Could it be that Bob Carver was, as Malitz said, sad and emotional about all the forum threads because Bob had no idea that the Company/Malitz changed the original design?

9. Quality of Parts. My unit does have some nice Dale resistors. The capacitors--especially where they. count in my book--were junk! I posted about that on my teardown last summer or so. The amp sounded great in my room and I thought someone made some poor choices. Even if you are someone who thinks coupling capacitors and the market for them involve snake oil, take a look at the size of the coupling caps made by Suntan in Hong Kong. They are the size of my fingernails! Some of the film caps are moving some serious voltage. I know, I tested them. So I put in some good stuff, which some may think is snake oil. But even a nice Wima or AMtrans would be affordable. Why cheap out for a price point at $3k?

10. Frank Malitz told me that they were building these so fast they didn't want to send one off to a publication for review. Hmmmm... I've heard of this actually happening when a product is first introduced, but we are years into this build. I don't and never believed that.

11. Why are no retailers actually selling this thing anymore? Hmmm... Why is Jim Clark, a dealer, defending the product, but there are circuitous and scant responses from Frank Malitz, Wyred4Sound, and even Bob Carver?

The whole thing is just sad. I have half a mind to go out to Washington with my amp and meet Bob. I wonder if he is aware or not of what these amps look like inside since Jordan put his name on the PCB.

12. Amir/Paul, any chance you can test the caps at C4 and C19 (going off memory as to the actual numbers) and let me know the values? My unit has nothing stuffed into the PCB in those slots. I raised that question when I first opened the unit. Malitz didn't know why and said on the phone he's not up to speed on the actual PCBs being used at that time.

Amir and Paul, thank you again.

-J

PS. I'm going back to throwing up in my mouth again. Sad. Just sad.

 

[SIY]

11. Why are no retailers actually selling this thing anymore? Hmmm... Why is Jim Clark, a dealer, defending the product...?

Jim Clark's stance may have been defensible before the facts (fraudulent specs, illegally dangerous construction) were brought forward. His continuing defense has crossed well into the area of unethical. He has proved himself crooked.

 

[Larry B. Larabee]

The amp blew its fuse while producing 60W at 1kHz, both channels driven. At while producing 15W at 20Hz, also both channels driven.

3A at 117VAC is around 360W.

So the amplifier efficiency was around 33% at 1kHz and less than 10% at 20kHz

PS. I am making simplification but they shouldn’t make much difference given the low efficiency values.

Thank goodness you said you were making a simplification!

 

[Xulonn]

Other oldies like me will confirm, but valve amps of old (and especially the UK tellies of the 50's to early 60's) used point to point wiring and often a rats-nest of wires underneath.

Indeed! Here's an example:

 

[john2017]

Hello ASR Forum! I'm a new poster here, but I have read copious reviews and posts over the last few years here and appreciate what ASR does. [That said, for full disclosure, I also put a ton of weight into how things sound; I don't care if a guitar amp tests that well--I want tone and features. Hifi is a bit similar and a bit different for me]. Getting my personal view out of the way....

I dropped in for a number of reasons.

1. First, I want to thank Amir and Paulbottlehead for their professionalism and courtesy. Paul dropped by my thread on Audiogon and was an absolute gentleman. I tore down the amp to confirm the presence of the Edcor OPT--to which Paul was ever so sweet and thankful. I didn't go further into the PT because I think I threw up in my mouth upon seeing that little guy.

2. I have nearly exclusively used this amp with super efficient loudspeakers (102dB), so before you or I call me an idiot for tweaking the amp (and also questioning its build quality early on, long before Amir's great work), I had no basis to even guess at its power output. If it could really put out 17w into an 8 ohm load, that's probably all that's needed to get my loudspeakers to sing.

3. I vote this amp not even worthy of ASR's voting system. It's despicable what the "Carver Corporation" has done in its marketing. I'm a lawyer by trade so I will say that there is just not enough evidence for me to find Bob culpable--at this juncture, based on what I've seen. I'll explain more below.

4. What the heck is going on with the lack of chassis grounding? I noticed it too and have been thinking about correcting it before Amir's review. That is totally inexcusable--note I'm a DIY hobbyist so keep in mind I'm not an authority on electrical safety, yet I do care about it and discharge caps when I go inside units.

5. Mine unit is clearly better built than Amir/Paul's unit--yet not by much.

6. The wiring to the output terminals makes me sad. Sad. Who would do such a thing? I've owned so much gear that I'm embarrassed to put out a number of units. I haven't seen anything like this since I took apart my JCPenny stereo in 1982. Note--my unit has nice heavy gauge wire running to the output terminals. What gives? This is inexcusable at this priceoint or any price where we are dealing with something that is supposed to be high fidelity.

7. The OPTs. Hmmmmm.... I have bought Edcors, Hammnonds and Lundhals. I had transformer hum (for OPT and PT) and talked with Malitz for a good bit on the phone about it. He said that they moved their sourcing of the transformers to another vendor and were having issues with some of them. Could it be that Bob Carver's original amp had better transformers and Malitz/Carver Corporation cheapened the whole design as an objective of making more money? I think that is a possibility.

8. Testing. It seems nearly indisputable that this thing as sold is not what the Company markets. Could it be that Bob Carver was, as Malitz said, sad and emotional about all the forum threads because Bob had no idea that the Company/Malitz changed the original design?

9. Quality of Parts. My unit does have some nice Dale resistors. The capacitors--especially where they. count in my book--were junk! I posted about that on my teardown last summer or so. The amp sounded great in my room and I thought someone made some poor choices. Even if you are someone who thinks coupling capacitors and the market for them involve snake oil, take a look at the size of the coupling caps made by Suntan in Hong Kong. They are the size of my fingernails! Some of the film caps are moving some serious voltage. I know, I tested them. So I put in some good stuff, which some may think is snake oil. But even a nice Wima or AMtrans would be affordable. Why cheap out for a price point at $3k?

10. Frank Malitz told me that they were building these so fast they didn't want to send one off to a publication for review. Hmmmm... I've heard of this actually happening when a product is first introduced, but we are years into this build. I don't and never believed that.

11. Why are no retailers actually selling this thing anymore? Hmmm... Why is Jim Clark, a dealer, defending the product, but there are circuitous and scant responses from Frank Malitz, Wyred4Sound, and even Bob Carver?

The whole thing is just sad. I have half a mind to go out to Washington with my amp and meet Bob. I wonder if he is aware or not of what these amps look like inside since Jordan put his name on the PCB.

12. Amir/Paul, any chance you can test the caps at C4 and C19 (going off memory as to the actual numbers) and let me know the values? My unit has nothing stuffed into the PCB in those slots. I raised that question when I first opened the unit. Malitz didn't know why and said on the phone he's not up to speed on the actual PCBs being used at that time.

Amir and Paul, thank you again.

-J

PS. I'm going back to throwing up in my mouth again. Sad. Just sad.

Would it be your impression then, that Bob Carver has very little to do with the actual running of the company, aside from design work, and that Frank Malitz is the guy in charge? What I know of him is that he is a marketing guy with little experience actually running a manufacturer. I believe he is more than capable of taking what was a true design from Bob and playing cheap on parts.

 

[traderitch]

I'm a lawyer by trade so I will say that there is just not enough evidence for me to find Bob culpable--at this juncture, based on what I've seen.

I am not defending Jim nor any of the people you mentioned.
The measurements and build quality are well documented in this thread.

My questions to you are simple.
Have you asked the dealer you purchased the unit from for a refund?
Are you just venting or are you seeking further restitution?
Did the perceived "sound" change after you opened up the unit?

 

[bidn]

Indeed! Here's an example:

View attachment 179721​

This is really a horror pic.

I would have preferred for you to have put a warning first, and let people click on a link (so as to hide it) before seeing it. Terrible pic to look at when you have a headache (my case today). I hope this pic will not return in my nightmares nor anyone else's...

 

[DSJR]

Indeed! Here's an example:

View attachment 179721​

I looked up the pic of the little amp used in the late 50's Pye Black Box record player (I inherited one from my grandparents and the cap has gone 'hummy' so it's in storage until I can hopefully get it fixed one day). Despite the thing being a low powered amp in a fancy cased 'record player,' it has a mains transformer and a three core mains wiring with solid chassis earth connection... As an entity, a lovely sweet tone for 78rpm records - the unit had a speaker each side and the intention was to put it in a corner to spread the sound out a bit before the 'Achoic' solid state stereo player came along some years later. I believe the 7W amp in my Hacker GP42 record player was also well designed using tag strips for the components. Only mentioning all this as even 'transportable record players' over the basic UK 'Dansette' level had well isolated and designed amps inside them.

 

[sarumbear]

Thank goodness you said you were making a simplification!

It’s only arithmetic…

 

[jbhiller]

Would it be your impression then, that Bob Carver has very little to do with the actual running of the company, aside from design work, and that Frank Malitz is the guy in charge? What I know of him is that he is a marketing guy with little experience actually running a manufacturer. I believe he is more than capable of taking what was a true design from Bob and playing cheap on parts.

I suppose that would be my impression, but who knows? Malitz told me that Bob is not an employee and not an owner. He designed the amps and the Company sells them.

 

[Fiddlefye]

I guess ASR tries to find the SOTA and a tube amplifier is not a good candidate. This was a different case. It was about proving if an audio legend is involved in false marketing or not. It turned out to be the case — sadly…

SOTA for SS and tube gear are two different (if related) topics. Tube amps are never going to compete in the absolute test stat sweepstakes. They do need to at least test respectably and meet the specs stated for them. The 275 clearly has not accomplished either aspect.

 

[solderdude]

I suppose it's not appropriate to call it earth since there is no earth reference in the 275

There is. The enclosure is even connected to it.

The shell of the RCA input jacks.

Yep that's ground. One has to take care when measuring this amp when the source and measurement system share a common ground.
One would be shorting part of the feedback path.
Fortunately the AP used by Amir has a floating input.

 

[Billy Budapest]

It is entirely possible that Carver (the man) designed the circuit the 275 is based on but then had nothing to do with the decision to use 15 watt transformers and with the failure to meet Type I wiring requirements.