Crimson 275 ASR review

[captainbeefheart]

1 hour ago, jjptkd said:

Looks like Bob Carver responded to the ASR thread:

 

"It has come to my attention that my amplifier design has come under sharp criticism on this forum. I am compelled to say that the 275 is safe as it is wired and assembled, and performs as it was designed. If a customer were to choose to utilize the earth ground pin of the IEC plug (to be connected to the chassis), this can be done at no cost. This design was well considered, and follows a long history of excellent products.

The 275 is a powerful, easy to listen to amplifier. I am happy with its design. In fact, this is one of the best designs I have produced. If for any reason a customer is disappointed in the performance or sound quality of this amplifier, they may return it for a full refund. The general reception of the 275 to date has been that of a high quality design, one that does not disappoint in any respect. The performance as it was measured by Amir does not do justice to the sound engineering of the 275.

I am not going to explain or attempt to refute the reasoning behind each criticism that has been made, the product speaks for itself and stands on its history of satisfaction. This amplifier was not designed to measure the best, it was designed to sound the best, and it does so at an affordable price in relation to products it might be fairly compared to. It is unfortunate for this type of bad press to make such an impression on people not directly familiar with the amplifier.

In conclusion, such criticism would be much harder to support in the presence of a 275 playing music. It would be all but impossible to argue that it’s deficient in any way when you experience the actual musical performance. I stand by that. The sound character of this amplifier is exactly what I wanted it to be. For any person with a 275 wanting to change the grounding or get a refund, email" info@bobcarvercorp.com.

Over and out,
Bob Carver

 

 

Dear Bob Carver,

 

We know the amplifier sounds good, 2 watt amplifiers also sound good but that was never any part of the criticism towards the Crimson 275.

 

What the concern is that you and everyone else that has responded that is monetarily invested with the sales in this amplifier is dodging any sort of explanation to why the amplifier does not meet advertised specifications. That's great you made a nice sounding amplifier, but why not be transparent and provide the actual real world performance instead of a very bloated version of them? Your specifications, along with the retail price are pretty clear, 20-20kHz 75 watts no more than 1% THD. Power is not actually any measure of quality, as mentioned a 2 watt amplifier can have amazing sound quality and fantastic measurements. Power is merely relative to what the consumer requires for his/her listening pleasure. So I ask, why inflate the power specification? Surely you have been in the business long enough to know how amplifier power is interpreted by how you presented it. How it is currently stated your amplifier should produce 75 watts into 8 ohms between frequencies 20Hz and 20kHz with less than 1% THD. Pretty clear if you ask me, and everyone that purchased it from you seemed to be under that impression as well. It is of no issue that your amplifier produces rated distortion and bandwidth at only 17 watts, power is not a means of measuring an amplifiers sound quality it's a relative quantity to who purchases it for their specific power needs. So again we are back to the sound quality of your amps are not under criticism, the false advertisement is. I think I can sum up your response to this issue  with much fewer words. It goes something like this;

 

My amp performs as designed (but not how it is presented in the sales literature specifications). We screwed up with the safety aspect so we will fix it for free. Also since we lied about the specs we will give you full refund.

 

See that is much easier for people to understand without all the excuses and deflection. We know the amp sounds good, I am very happy to see you will resolve the safety issue at no cost to the customer or if they are unhappy with finding out the specifications are inaccurate and the amplifier cannot make the customers power requirements you will give a full refund. Cut through the public relations BS and be honest, glad you are making it right with people who purchased this amplifier.

 

-anon

[henry4841]

The misconception of more power means better sound is alive and well. Evident in this amplifier and the power rating misrepresented in his ads and spec's. A very good amplifier, from all that has been said on this thread, that the seller thinks needs over rated power specifications to create more sales. I remember too well the power wars of the 70's with all the big players creating bigger and bigger amplifiers. I have been restoring some of the 70's lower power receivers and amplifiers and even ones with 15 watts per channel drive some 85db bedroom speakers plenty loud and sound really good.  

[captainbeefheart]

6 hours ago, henry4841 said:

The misconception of more power means better sound is alive and well. Evident in this amplifier and the power rating misrepresented in his ads and spec's. A very good amplifier, from all that has been said on this thread, that the seller thinks needs over rated power specifications to create more sales. I remember too well the power wars of the 70's with all the big players creating bigger and bigger amplifiers. I have been restoring some of the 70's lower power receivers and amplifiers and even ones with 15 watts per channel drive some 85db bedroom speakers plenty loud and sound really good.  

 

Bingo!

 

They knew exactly what they were doing. They made sure it can provide a transient peak power for short periods which is fine they just should have rated the amplifier like this;

 

"15 watts 20-20kHz with no more than 1% THD, Provides up to 70 watts peak power for dynamic music transients"

 

Power sells, it's just a fact. They certainly knew that if they rated the amplifier as a 75 watt amplifier they can  increase sales substantially.

[KT88]

At the level of understanding of a consumer I could have been:

 

Bob Carver: „If a customer were to choose to utilize the earth ground pin of the IEC plug (to be connected to the chassis), this can be done at no cost.“.

 

Let's assume that as a consumer I have no idea about technology and safety requirements and let's further assume that I would never have unscrewed the amp to inspect its grounding. Then the sentence sounds to me something like:

 

If a consumer wants to choose that we connect the brakes of his car properly, we do it without cost.

 

The justification of wanting to achieve the best sound, but regardless of whether the performance specifications are correct is also unacceptable. You can't set off one against the other.

I may have no idea as a consumer but I know, for example, from the manufacturer that my speakers really need 75 watts to work properly. Then this must be a reliable specification of an amp. So it may be by chance that 275 customers with very sensitive speakers never have a complaint but those with power hungry 84 dB 1W/1 meter don't understand why it doesn't work. 

 

I don't know what went wrong with them, but obviously there was no final inspection and technical review of the design and performance specifications and safety requirements

 

I say this deliberately from the perspective of the consumer without knowledge that he does not have to have to be a consumer.

 

 

 

[KT88]

4 hours ago, captainbeefheart said:

 

Bingo!

 

They knew exactly what they were doing. They made sure it can provide a transient peak power for short periods which is fine they just should have rated the amplifier like this;

 

"15 watts 20-20kHz with no more than 1% THD, Provides up to 70 watts peak power for dynamic music transients"

 

Power sells, it's just a fact. They certainly knew that if they rated the amplifier as a 75 watt amplifier they can  increase sales substantially.

In addition to this misdirection, I find it an inappropriately deceptive and also brazen naming. "Crimson 275" ...who doesn't immediately think of the icon Mcintosh 275. And the perfidious thing is, everyone should think of this icon. For the unsuspecting consumer it looks "technically" very similar, four Coke bottles in line in front of three "huge" transformers.

Even if it was not intentional unconsciously it will have played a role in marketing

TBH that was from my point of view also the reason to hype up the power to 75 watt.

I assume that Mcintosh has not legally trademarked the number 275, but it has a similar flavor as if Kia were to name its next sports car the Kia 911 (where 911 is trademarked by Porsche).

[captainbeefheart]

33 minutes ago, KT88 said:

In addition to this misdirection, I find it an inappropriately deceptive and also brazen naming. "Crimson 275" ...who doesn't immediately think of the icon Mcintosh 275. And the perfidious thing is, everyone should think of this icon. For the unsuspecting consumer it looks "technically" very similar, four Coke bottles in line in front of three "huge" transformers.

Even if it was not intentional unconsciously it will have played a role in marketing

TBH that was from my point of view also the reason to hype up the power to 75 watt.

I assume that Mcintosh has not legally trademarked the number 275, but it has a similar flavor as if Kia were to name its next sports car the Kia 911 (where 911 is trademarked by Porsche).

 

Well said.

 

I 100% agree they new exactly what they were doing when they marketed this amplifier with 275 in the name. People are all over something they think performs like a McIntosh 275 with 75 real continuous watts per channel but for $2,000 dollars less. Power sells, I am certain it was a marketing and engineering decision to make the B+ over 600v and use a 2.5k plate to plate load, that way there they can technically make 75 watts, just not continuous and not over the entire audio bandwidth. Carver is innovative, and that is the first time I have seen a tube amp designed this way to provide a very short duration of higher transient power well above it's rated continuous power. They very well could have chosen a 350v plate supply for the KT120 but it wouldn't have reached it's transient peak power of 75 watts. The non-linear distortion created by the output transformer at low frequencies and higher power levels creates a lot of distortion but it's even order distortion and isn't necessarily heard as 'bad'. Between the bass boost they put into it's frequency response and the high amount of even order harmonic distortion at low frequencies it can be easily heard as 'full' bass as the distortion is going to mostly be an octave above the fundamental adding in more low frequency information. So for a 27Hz fundamental (low A on a piano) the output will also contain a 54Hz signal from the added distortion reinforcing the 27Hz fundamental. Now this can sound good as the amplifier reviews have proved but in it is not regarded as high fidelity as it's not an accurate reproduction of the original information. This is how many of those amplifiers with wimpy output transformers still have good bass sound, it's not that bass is attenuated, they are distorted adding in information that isn't originally in the program material making it not exactly hifi but acceptable in that it doesn't sound 'bad'.

 

This would not be tolerated in the auto industry. If you your truck is rated at 400 ft/lbs of torque and you go to pull a boat and it really only has 150 ft/lbs of torque you will be pretty disappointed going up hills and accelerating from a complete stop. It doesn't surprise me how Bob finally addressed the issue, he isn't going to admit any malicious intent and deflect the real issue by just talking about how the amp sound good.

 

I really would love one of these on my bench to test myself. I would love to see if the DC restorer circuit even does anything. I would also love the answer of how much voltage is across C36 and C37 during power up as they are only rated at 450v and without the preamp tubes conducting (they need time to warm up) I am certain the voltage rating of those capacitors will be grossly exceeded!! They should have at the very least installed a shunt resistor to make sure there is always load and a drop across the dropping resistors in the filter network during power on. Or better, I make sure the voltage rating of all the capacitors in the power supply can handle full unloaded B+ in the chance someone may power it on without any tubes installed. It would not have cost much more money at all to use two 350v caps in series for a combined rating of 700v, instead they chose to rate the capacitors for working voltages which is poor engineering with a SS rectifier. I am willing to bet C36 and C37 will start to fail soon since these have been out for a little while now and they can only take so much over voltage abuse in their lifespan.

[Khornukopia]

On 1/21/2022 at 8:24 PM, jjptkd said:

Looks like Bob Carver responded to the ASR thread:

 

"It has come to my attention that my amplifier design has come under sharp criticism on this forum. I am compelled to say that the 275 is safe as it is wired and assembled, and performs as it was designed. If a customer were to choose to utilize the earth ground pin of the IEC plug (to be connected to the chassis), this can be done at no cost. This design was well considered, and follows a long history of excellent products.

The 275 is a powerful, easy to listen to amplifier. I am happy with its design. In fact, this is one of the best designs I have produced. If for any reason a customer is disappointed in the performance or sound quality of this amplifier, they may return it for a full refund. The general reception of the 275 to date has been that of a high quality design, one that does not disappoint in any respect. The performance as it was measured by Amir does not do justice to the sound engineering of the 275.

I am not going to explain or attempt to refute the reasoning behind each criticism that has been made, the product speaks for itself and stands on its history of satisfaction. This amplifier was not designed to measure the best, it was designed to sound the best, and it does so at an affordable price in relation to products it might be fairly compared to. It is unfortunate for this type of bad press to make such an impression on people not directly familiar with the amplifier.

In conclusion, such criticism would be much harder to support in the presence of a 275 playing music. It would be all but impossible to argue that it’s deficient in any way when you experience the actual musical performance. I stand by that. The sound character of this amplifier is exactly what I wanted it to be. For any person with a 275 wanting to change the grounding or get a refund, email" info@bobcarvercorp.com.

Over and out,
Bob Carver

 

It will be interesting to read about, if and when someone has a successfully fulfilled refund request.

[OO1]

On 1/22/2022 at 7:04 AM, henry4841 said:

 I have been restoring some of the 70's lower power receivers and amplifiers and even ones with 15 watts per channel drive some 85db bedroom speakers plenty loud and sound really good.  

 85  dB  in a Bedroom , I gotta try this 

[CWelsh]

2 hours ago, 001 said:

 85  dB  in a Bedroom , I gotta try this 

That's what she said.

[jjptkd]

And another reply from Bob Carver over on ASR:

 

 

 

 

"Hello, Bob here. Here are my replies to your questions.

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

Yes, the vertically mounted board is the power supply. The DC Restorer is on the main board, mechanically appropriate and sound. Bonding to the chassis was chosen. Bonding of assemblies, with service life greater than 20 years are common today, even in high end automobiles and aircraft. The low operating temps are compatible with bonding. Again, completely appropriate and sound.

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

Yes. We have used this meter many years without any failures. Serviceability is not likely to be of concern. Manufacturing Engineering chose to bond the meter.

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

Yes. They work quite well driving loudspeakers. In combination with back EMF feedback, and our DC restorer tracking bias supply, the ability of a tube amp to increase voltage with increases in impedance at low frequencies is inherent in my design. Together, these make music as a system.

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

22 gauge was determined to be proper by Manufacturing Engineers. A change to larger diameter (14 gauge) came later in the first year of production for cosmetic reasons. Units over the last 2 years have heavier wiring.

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

Yes. Supply chain issues have limited choices of brand names at times. Parts that meet or exceed the original part specs are acceptable.

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)

You have some power transformer hum. All three transformers mount directly to the chassis. Transformer hum can become microphonic in tube amps and make the situation worse. Most of the amps are quiet, but a few have hummed. The later units had isolation added and the issue was resolved. You can return your amp for the update at no charge. We will pay the shipping both directions.

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?

The Edcor products are high quality and were never an issue. Although the chassis is 1/8” thick aluminum, a slight sympathetic resonance can amplify the hum to audible levels. Talk to your dealer or call the phone number on my web site. We will make the improvements at no charge.

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 that this scheme is safe and acceptable?

Yes, it is safe. Note most audio product use ungrounded cords. We have done this for several decades and over untold thousands of products with nary an issue.

If a high voltage wire were to touch the inside of the chassis the B+ fuse will blow.

If by chance, the power cord was wired incorrectly by a builder, it would likely cause hum. Please return the unit. We will pay shipping both directions and check it. If you prefer to have the earth ground connected, we can also do that at no charge.

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

It does have a 5 year warranty. From the original date of purchase with a receipt.

The amplifier sounds wonderful with adequate reserves while driving loudspeaker loads.

I have been designing amplifiers since college, and since 1972 as a business. The 275 sounds and performs exactly the way I intended. I have designed and built many conventional amplifiers that test terrific by conventional standards. I have been doing this most of life. The specifications are being updated to better quantify our test procedures.

We are tooling up presently for manufacture under my close guidance and oversight.

Thank you for bringing this to my attention. I have some good people on my team. I have some new ideas coming in 2022 and some long term plans for my business which I think everyone will find exciting. Feel free to contact us from our website or call the phone number listed (815) 985-3557.

Warmest and best,

Bob Carver"

[mike stehr]

15 hours ago, jjptkd said:

Suntan brand

I had some Suntan branded trim pots once...they were garbage. Go with Bourns.

[a9050lx]

15 watt Edcor output transformers? Does a HK Citation II output transformer even do 75 watts? Probably, but 5 times the size maybe?