Carver Crimson 275 Review (Tube Amp)

[Jim Clark]

Thank you for clarifying those things, Mr. Sarmento.

Would you be able to confirm that the Crimson 275 is spec'd with 15W Edcor output transformers? I have asked that question to Frank Malitz/Bob Carver several times and have not heard back. There are at least two units purchased from authorized dealers with 15w Edcor transformers in them. It would be helpful to know if this is OEM specified.

I think some of chatter has to do with the perception that there is a lack of transparency about the amplifier. Mr. Malitz has not provided straightforward answers to simple questions--instead he uses sales techniques to respond. For example. when asked about the PT and OPTs in this amp, Frank responded with paragraphs explaining that many speaker manufacturers recommend the Crimson 275 with their loudspeakers and they wouldn't do so if it were not a lovely sounding amplifier.

That may be very true. But the question is a simple one--Were the Edcor transformers specified in the design or appropriate for the design?

While I appreciate how some may feel that the social media "pitchforks" and "mob" are out in full force, I think it's important to keep something in mind: Folks have legitimate, simple questions about the amplifier to which they cannot get responses. This amplifier cost many of us $3k (with tax) and when we get evasive, salesy responses--or, in the alternative, radio silence--it only increases the skepticism.

For the record, I love Bob Carver's history and him as a person. The amp does indeed sound good with my high efficiency speakers. I'd love to have Amir and any ASR gang over to blind A-B it against some of the top performing spec-wise amplifiers. That's part of the fun.

That said, folks have raised these salient questions to which there has been utterly no response--just conclusory statements by Malitz and now Bob. Maybe you could help answer them as your firm looks to have built a good number of copies.

1. Is mounting the DC restorer circuit by gluing it vertically to the chassis part of the design?

2. Is mounting the meter to the chassis by gluing it part of the design?

3. Are the Edcor 15w OPTs part of the design?

4. What gauge hookup wire is supposed to be running from the PCB to the speaker output terminals?

5. Does the design-manufacturing process allow for substitution of Panasonic film caps with Suntan brand or other lesser known caps?

6. Have there been reports of transformer hum? I have owned two units and both hum/buzz at the transformers with no signal and volume totally attenuated (not a sound coming from the speakers, but buzz/hum coming from the transformers (all 3)?

7. Frank Malitz stated there was a problem with transformers when the vendor deviated from specification, and that resolved. Would that vendor be Edcor? What can be done to silence the transformers for those with those issues?

8. Grounding. Are you aware of what many of us view as a problem with the grounding scheme in this amplifier? Specifically, several of us have the neutral running to fuse and no chassis grounding or ground to earth. Do you believe these scheme is safe and acceptable?

This unit is supposed to have a 5 year warranty and many of us are just trying to figure out where things stand.

I'm not trying to come at anybody. I like the amp. I'm just trying to navigate through this and Frank Malitz and Bob just say: (a) the amp is awesome; (b) the amp is totally safe: (c) everyone who hears it loves it; (d) Amir and associates test it incorrectly.

I'm sure you can appreciate that when a consumer spends $3k on something they want to know they bought what was sold to them and it is safe.

Thank you for your time and any information you can provide. I can assure you that many consumers these days appreciate substantively meaningful responses form the manufacturers/dealers of the equipment they buy at this price level. Thank you!

Hello, JB.

I copied your questions and forwarded them to Bob. He doesn't spend much time on the internet. I'm sure he will respond in a day or two. Thank you.

 

[wwasilev]

View attachment 181539

Maybe a Crimson 215 is in the works.

 

[MakeMineVinyl]

Hello, JB.

I copied your questions and forwarded them to Bob. He doesn't spend much time on the internet. I'm sure he will respond in a day or two. Thank you.

It's the squishiness of the explanations and rationale for this amplifier which is most frustrating. The transformers say '15 watts' clear as day. What could Bob possibly add which would illuminate this further? Just admit that somebody got caught with their design pants down, that combined with hubris. Please just own up to it and revise the bloody specs and fix the ground and QC and move on while the parties involved have a shread of integrity left. Please stop punching yourself in the face.

 

[L0rdGwyn]

Well, no. There is not a single manufacturer who declares their 300B SE amplifier will output more than 10W output power. Most of the manufacturers declare about 8W output power, and all measurements of 300B SE amps I am aware of show 7 - 8W continuous power output at 3% THD.

There are ways to get 10W out of a single-ended 300B. Low distortion too if you aren't averse to NFB.

 

[Larry B. Larabee]

If you get close to the rated output at midband frequencies how is this a 15w OPT?

 

[wwasilev]

The amp measured 17W at 1% THD, into 4 ohms at 1 kHz, continuous.

 

[Larry B. Larabee]

The amp measured 17W at 1% THD, into 4 ohms at 1 kHz, continuous.

This is from Paul's measurements:
Here's a nice big wave with the amp at 1kHz 5% THD making lots and lots of power. Note that this is consistent with my findings of 75W being available at 1kHz but at higher distortion.

 

[wwasilev]

Wut? The numbers are from Amir's review.

 

[jbhiller]

Hello, JB.

I copied your questions and forwarded them to Bob. He doesn't spend much time on the internet. I'm sure he will respond in a day or two. Thank you.

Thank you Jim!

 

[Larry B. Larabee]

So, I thought what if you used a line distribution transformer backwards. I found a thread on diyaudio about just that and a reference to blockhead.com maybe doing that same thing. I didn't read it.

 

[Larry B. Larabee]

Wut? The numbers are from Amir's review.

Paul's Carver measurement thread

 

[Vladimir Filevski]

I’m confused. You are saying no to me saying my 300 b would measure poorly? I’m quite certain it does measure poorly. Also I’m very familiar with how much 300 B tunes put put out when using a single power tube per side. I’m pretty sure it tests pretty clean in the first watt and then distorts quickly. I’m not sure what you are saying I’m wrong about. It’s 8 w per side.

300B SE amp will measure poorly distortion wise, i.e. it will show high distortion, but it will deliver 8W with 3% THD. Nobody claims it will deliver 40W (5 times 8W) at 3% THD! Compare that with the Bob Carver Corporation claim that Crimson 275 will deliver 75W at 1% THD, which is 5 times the actual measured 15W max power output.

 

[sergeauckland]

If you get close to the rated output at midband frequencies how is this a 15w OPT?

Just because it's only at mid frequencies. At 30Hz, it would be 15w or possibly even less. It may not reach any more than 15 watts continuous at 20kHz due to losses.
A good transformer rated at 75watts will do that down to 20Hz and even a half-decent one will manage 30Hz with low distortion. Equally, a 75w rated transformer will do a lot more at mid frequencies, limited much more by the output valves and the HT voltage than the transformer itself. Small transformers have small cores that saturate at low frequencies at low powers. It takes a lot of iron to do 75 watts at low frequencies, and a small transformer won't do it.

S

 

[Vladimir Filevski]

There are ways to get 10W out of a single-ended 300B. Low distortion too if you aren't averse to NFB.

Yes, but you will not get 40W (5 times 8W) or 50W (5 times 10W) from 300B amp, and no way to get 75W (5 times 15W) from Crimson 275.

 

[wwasilev]

Paul's Carver measurement thread

I'm not following Paul's thread but I quick peek shows that he also measured 17W at 1kHz 0.99% THD, continuous. I don't see any disagreement between the two sets of measurements in this regard. The 275 looks like a 17W amp to me. How would you rate it?

 

[Larry B. Larabee]

I'm not following Paul's thread but I quick peek shows that he also measured 17W at 1kHz 0.99% THD, continuous. I don't see any disagreement between the two sets of measurements in this regard. The 275 looks like a 17W amp to me. How would you rate it?

It doesn't rate by any stretch. I just pointed out that it puts out 75w/1khz at 5% thd.

 

[SIY]

It doesn't rate by any stretch. I just pointed out that it puts out 75w/1khz at 5% thd.

But their spec calls out 20-20k. So what it does at midband is meaningless. It does not meet their advertised performance, they know it doesn't, and they're just brazening it out.

We're well past the point where any integrity can be saved.

 

[paulbottlehead]

If you get close to the rated output at midband frequencies how is this a 15w OPT?

Magnetic flux goes up as frequency decreases.
Magnetic flux goes up as voltage increases.

A typical output transformer that can handle 100W at 40Hz would be capable of 200W at 80Hz, and likewise 50W at 20Hz. It's up to the transformer winder to specify acceptable power output at a given frequency. The typical 15W channel frame Edcor appears to be rated for 15W at 70Hz.
Example Edcor 15W channel frame

 

[Larry B. Larabee]

Edcor appears to be rated for 15W at 70Hz

This is the explanation I ( everybody?) wanted.
thanks

What about using a distribution transformer as an OPT, any thoughts?

 

[Blumlein 88]

This is the explanation I ( everybody?) wanted.
thanks

What about using a distribution transformer as an OPT, any thoughts?

Why? Edcor makes a 100 watt opt. Use that.