Bob Carver Corporation Products


Bob Carver Corporation takes pride in every piece of gear we ship. However, if there is a mistake, please call us immediately, and we will make it right. If a product does not seem to be functioning correctly, please call us and we will do our best to help walk you through the problem.

If you are located in the USA and need to have your unit repaired, you will get the fastest response by calling us at (847) 668-4519.  We will provide you with return instructions and shipping information. This will enable us to correctly identify your unit and ensure timely repair and return. Please ship only the unit that needs repair, and pack it in the original box and packing material if possible. You are responsible for shipping your unit to our facility and for insuring the shipment.

Please make sure to write your contact information on a note inside the package.

We will return the unit back to you prepaid, if in warranty. If not, you'll be billed for freight.

Please note that you may void your Limited Warranty if you, or someone other than Bob Carver Corporation attempts to repair your Bob Carver Corporation product.

Service and support form for owners of

Bob Carver Corporation products

Power Amplifiers

What impedances can the Crimson/Raven 350 handle?

Some of the speakers I have most admired throughout the years were very low impedance. Therefore I have designed under-1-ohm output capability into both my 350 and 900 watt amps. You will have no problem with virtually any speaker system available today — or some even more finicky classic legacy speakers.

Why on earth would I need so much power?  I don't play my music at shock volume.

If you compare the maximum volume of a 150-watt amplifier with a 300-watt amplifier, the difference is only 3 dB, barely greater than the ability of the human ear to hear the difference. It takes an amplifier with 10 times more power (1500 watts!) to be perceived as being twice as loud—a 10 dB increase. So the first part of the answer is that what seems like lots more watts is only a slight increase in volume. However, more watts can create a dramatic increase in realism. It takes a lot of power to accurately create many musical waveforms — think kick drums, snares and cymbals. In real life they happen in a fraction of a second. When a physical speaker is called upon to reproduce them, it must react instantaneously. Without sufficient power, the speaker transducer fails to move fast enough. You hear a mushy, less-realistic sound.

How long will the tubes in my Caver Amplifier last?

Answer goes here.


No sound — but the amp is on, plugged in, and the tubes are glowing.

1. Rotate the Crimson/Raven/Silver Seven volume control counter-clockwise to fully turn down the volume. 2. Make sure that your output source (preamplifier, DAC. etc.) is operating correctly and playing. This may require plugging in headphones, ear buds or routing the input device's output to a different amplifier/speaker combination (still have that '90's boom box?). 3. Check the connections between your output device and your amplifier(s). Even pricey connection cables can fail. 4. Check the connections between your amplifier(s) and your loudspeakers. 5. Carefully rotate the Crimson/Raven/Silver Seven volume control clockwise. 6. Call us! This shouldn't happen and we're eager to get you back up and running.

Sound is coming from only one loudspeaker (Crimson and Raven)

1. Make sure that your input device (turntable, DAC. etc.) is operating correctly and playing. This may entail connecting headphones, ear buds or other listening device. 2. Check the connections between your output device and your amplifier(s). 3. Check the connections between your amplifier(s) and your loudspeakers. 4. Change the left and right output device-to-amplifer connections. If sound comes from the other loudspeaker now, the problem is with one channel of your input device. Change the left and right output device-to-amplifer connections back to their correct polarity before proceeding. 5. Change the left and right amplifer-to-speaker connections. If sound comes from the other loudspeaker now, the problem is with one channel of your Bob Carver Amplifier. Call us.

My amp has no sound and my connections are correct.

The owners' manuals deal with this. All Bob Carver Corp amplifiers can repair defective tubes if the failure is due to an impurity within the glass bottle--by far, the most common cause of failure. There are two fuses on the back panel. Your "tube" fuse blew to protect the tube and supporting circuitry. No other brand can do this. Replace the fuse and the tube is now "healed" and you may resume your enjoyment with no degradation in perfomance at all!

Is the warranty transferable?

No, our warranties apply to the original purchaser only.

Can I upgrade to KT150s?

The Crimson 275 cannot support the KT150 effectively. No benefit. The 350-series may pick up 12 watts or so. No audible benfit. For the Silver Seven Series, contact Frank Malitz at 847-668-4519 and have your particualr model number availble.

Why don't you list damping factor on your spec page?

We do not list damping factor becase, simply put, much of the general population of audio enthusiasts do not understand the lack of importance. The great majority of world-class tube amps, all have an output impedence between one and two ohms. Ours is between 1.5 and 1.8 resuling in a damping factor below 15 for all of these, depending on the brand. We suggest this improves the listening experience. It's important that you realize that the very circuit designs optimizing certain specifications may actully degrade the sound while posting better (meaningless) numbers. Listen to the product and you'll see. In the casse of the Crimson 275, compare it to any amplifier up to around $10,000 and you'll be convinced!

Where is your product manufactured?

All Bob Carver Corporation products are hand-assembled in central California

Just what is the best bias setting; I've gotten different answers.

Bob Carver prefers 80ma which would provide a slightiy larger soundstage and a bit more depth (he's really intro that aspect). We ship at 100ma for a bit more detail and a lttle less of the spacial aspects metioned above. If you change output tubes, check the bias. Note that once adjusted, the bias stays stable and may never need an adustment until the tubes age a bit. You'll not damge the amp no matter the setting.

My bias meter jumps around when playing music. Does this mean the bias is constantly changing?

When playing music, the meter becomes a VU meter indicating a working condition--entirely normal.

The Crimson 275 seems lighter than other tube amps of this power.

It is lighter! Thanks to Bob's research on transformers and metalurgy, these proprietary designs are more efficient than ordinary transformers allowing for a more compact size, less weight, less noise and less heat and the remarkable power we can get from a single pair of KT120s per channel without compromising longevity or performance.

Can I buy directly from the factory and get a better price?

We generally prefer you buy from an authorized EXPERIENCED retailer/installer. If there are no authorized dealers withing a reasonable distance. we may suggest internet resellers who offer excellent supprt. We have no control over the pricing nationwide, but the value has been solidly established so you're not likley to save money by buying from us as opposed to an actual audio salon equipped to guide you and back up the product. We cannot, for example, provide you with a demonstration and you'd have no return privileges.

Can you fix my old Carver stuff? Bob seems to move from company to company.

In forty years, Bob Carver has established only four real audio companies--Phase Linear, Carver, Sunfire and now, the Bob Carver Company. In the case of the former three, the corporate "suits" and Bob regulary disagreed on the direction of the brand and he left each reluctantly. The current company is more consistent with his vision--ultra-high-performance tube electronics at merely high-performance pricing with innovations on every model and no going down-market, no TVs, no car audio, no portable blue-tooth speakers and no entry-lever mundane prodicts, yet all with longer warranties, longer lifespan and better customer service than any brand in our industry's history. Yes, we can arrange service on any brand!

In the forums and YouTube Bob Carver videos, there's talk of the ear-brain interface. What's that about and don't all companies do this?

If they do, they are unknown to us and likely to be accidental. Dr. Carver has a background in physiology, as well as electronic design and engineering and his doctorate is in physics. He develioped monclonal antibodoes to fight cancer and infections and established a facility to manufacture the antibodies as well. Every product we make takes the ear-brain interface into consideration. For example, without providing propietary details, Bob's research is consistent with that of Frank McIntosh, Stu Hegeman, the BBC, the Crown Corporation and Sigfied Linkwitz despite minor diifernces in application, but Bob has made more prodcts following those precepts than all other companies combined. The goal is the reduction of listener fatigue, imprecise imaging and a small tight soundstage lacking envelopment, depth and openness. All our amplifiers use this tehnology as did the loudspeakers he's maufactured in the past. For more details, contact Frank Malitz at 847-668-4519.

Tube Rolling

Are Tung-Sol KT120's the only tubes that I can use in my Crimson/Raven or Silver Seven?

There are actually a lot of different brands and types of tubes that could be used in my amplifiers. Answer continues from here.

How can tubes in your amps stay trouble-free for up to 48 years when other manufacturers recommend replacement every 2 to 3 years?

The answer is the DC restorer. Here’s how. Most amps idle the output tubes at an average of 32 watts or so. Now the DC restorer allows the tubes to idle at about 9.75 watts. Since tube longevity is roughly proportional to the plate dissipation raised to the 2.3 power, we have 32 divided by 9.75 raised to the power of 2.3 = 15.4. Finally, 15.4 X 3 years = 46 years. I have also noticed that many console amplifiers have 50-year-old tubes right here on eBay, and those tubes check out great.

Questions are organized by subject or use the search tool at right 


Thanks for submitting! We'll get back to you!

Frequently Asked Questions

Bob Carver Corporation



Sunfire®, original Carver and
Phase Linear products…


Bob and his staff regret not being able to render service or support on these products. But we are happy to help put you in contact with a Service Centers that still repair Phase Linear, original Carver and Sunfire products. 


Click here to contact a Phase Linear,
Carver and Sunfire Product Service Center.

Sunfire, a division of Core Brands, LLC., may also be contacted through their web site at



For Legacy Products, See                          Below


Due to the Nature of Our Propitiatory Circuit Design,

The Bob Corporation 

Authorizes NO Outside Service Facilities

For our Authorized Legacy Brands, We have Two--One Each, East and West of the Mississippi River, Click on the Link Below.

Other Facilities Claiming to be Authorized May Not be;

Check First!