@jbhiller So Bob offers a full refund to consumers of his product. This seems quite strange to me..as IF there is a safety hazard should he not be requiring all units in the field be recalled and corrected?? If there is no issue, why offer a refund? Plus, if there is a safety issue, why would he still want to have units in the field that could do harm ( maybe even kill?) and suffer the consequences of that action...doesn't really make any sense to me!
Owners of Carver Crimson 275 -Caution/Warning--Potential Increased Risk of Electric Shock
What's going on?: If you own a Carver Crimson 275 amplifier there is a real potential that your amplifier does not have a proper chassis grounding scheme inside. There is a type of grounding system involved, but the third prong of the IEC socket (the actual electrical socket on the inside of the amplifier) is left wide open on my amplifier and and at least one other amp that I have virtually confirmed (not firsthand--only through another owner).
What does this mean?: If one of the hookup wires carrying power/B+ came loose from its soldered weld and touched either the chassis or something conductive to the chassis and the user then touched the chassis/unit with the power on they could get a significant electric shock. There are some seriously high voltages in this tube amp (like many amps of its topology) and the result could be lethal.
Carver Corporation's Response to Status on Grounding: I have notified Frank Malitz of the Carver Corporation about this problem. He responded to me in writing saying the following, exact quotation, nothing more or less:
"the design is under review with engineering and I'll contact you tomorrow." (F. Malitz)
In the interim, users may be at an increased risk of shock and bodily harm. I would encourage you to check with an electronics expert or the Carver Corporation for further guidance, as I'm not qualified to say more than there's no confirmed chassis ground in the unit that I have and at least one other unit.
Finally, unless you are qualified in working with high voltages do not open your unit to check for the ground wire running to the ground prong on the IEC. Please note that doing so with or without a chassis ground should only be done by someone experienced with electronics--i.e. caps must be discharged and care taken to cause an issue. Seek professional help.
I'm just a music lover and hobbyist. I'm merely relaying this information out of concern for the safety of fellow humans. I'm not an expert and perhaps an expert will rule out this identified potential increased risk as non-existent. For now, I can say that it is my opinion that there is a real reason to believe that grounding scheme might be deficient and I will not be using my amp until this is sorted out.
I'll report any response from the Carver Corporation as soon as I hear back. For now, my amp will sit unplugged.
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@daveyf , Agreed. Personally I like the sound of the amp quite a bit through high-efficiency speakers. However, this whole thing is a dog and pony show. I really respect Bob and what he has done for the hi-fi community. However, the responses from him and others associated with this, including Bob Carver and Wyred4Sound are just bizarre. I would be quicker to believe Bob Carver and his associates, saying that the amp is safe, if they actually gave a basis as to why. Specifically I mean, just tell me why from an engineering perspective this is safe. Instead they just make a blanket conclusion that it is safe and saying that you can have a full refund if you want it. They also do say that they will ground it to the chassis if you would like. That’s good. I was just looking for a little more transparency what is going on, especially from the folks that designed, manufactured and market of the unit. |
Unless I am reading the above quote wrong Bob Carver does not own Bob Carver Corporation. Bob Carver is hired on as a designer. If a refund is being offered for the amp it is being paid by the present owners of the company. FWIW, reading the first three paragraphs from the post of Frank Malitz on AUDIOKARMA, Bob Carver was not involved in the production of the Carver Crimson 275 Amplifier. That would probably included involvement in parts or parts quality.
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No I am not saying that at all. There are two grounding systems involved. One is the "Circuit Ground". (Internal electronics circuitry ground). The other is the AC mains power Safety Equipment Grounding. (Connection to the AC mains Equipment Grounding System at the main electrical service panel). Both are connected to the chassis. Though some manufacturers will employ a Ground Lift switch that will lift the signal ground from the chassis when an EGC is used and there is a ground loop hum problem. If the Carver amp was CLASS II wired, using double insulated power wiring, the only ground connection to the chassis would be the "Circuit Ground". Therein power supply B- and signal ground. The metal chassis has to be connected to them to work properly. This from the late Charles Hansen:
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Reading the article posted on ASR would indicate that this amp is really a POS..particularly for the money asked… But it would be more acceptable if it was advertised as a 15 watt amp with a design by Carver at a more appropriate price to its quality. Instead, the company seems willing to risk liability and damages, with the full expectation that enough profits will accrue to off-set the risk. A common business practice these days… |
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