Bob has been making a few pair of these over the past 2-3 years & selling them on ebay. Most were 180-240 watts, but these monsters have the new KT-120 tubes & upgraded transformers, etc. They are stunning!
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&hash=item2a0f1b85e2&item=180642088418&nma=true&pt=Vintage_Electronics_R2&rt=nc&si=KYqRyNpOye1MFNPTmn9BduFb5X0%253DStunning!
Here's the always interesting Q&A from the auction:
Q: Hi Bob. I'm a little confused, perhaps you can straighten me out. In the first part of the description, you state that "I designed and wound a massive new and powerful output transformer." Later, you mention "Though I have become pretty good at winding them myself, it takes too long" and "I had the thought of getting a commercial transformer company to make them for me according to my plans, but the cost was too high." So,to clarify my clouded brain, are the transformers installed in the BLACK BEAUTY your own handiwork? Also, you mention that "A switch that changes the feedback from classical (vintage) to contemporary." Obviously, by 'vintage,' you must mean a Citation-like sound, right? But by 'contemporary' do you mean more like a current solid-state unit, e.g., Sunfire, or a modern vacuum tube unit, e.g., Audio Research? I'm using other manufacturers names for comparative purposes only; I'm certain that both positions represent the "heart and soul" of Bob Carver! Thanks! -Dave Mar-21-11
A: Hi Dave, I can understand how you are confused because I'm confused myself. If I'm confused how could you possibly not be confused? Now you are making me think! Okay, here goes. I did teach myself how to wind them by copying the original units. Subsequently I changed the design from pie-wound to layer-wound, and have been more than pleased with the way they turned out. I used modern steel and segmented windings. Nobody wanted to pie-wind them - it takes too long, is very difficult, is too expensive and not necessary anyway. At this point in time the units in these Black Beauties are my own handiwork because I have not yet found a transformer house that will wind them for me (at least the way I want them wound), but I will soon. It's hard to wind output transformers - power transformers are easy - and I for one have developed a new-found respect and admiration for the handful of transformer guys on our planet who do it well. As for the feedback switch, "classical" refers to the amount of negative feedback = 20dB. "Contemporary" = 11dB. Modern tube amp designers often prefer less feedback than do vintage designers. That's mostly due to the fact that it's quite difficult to get substantial feedback around modern transformers (built with a rational budget in mind). Sometimes it seems that all the vintage units were designed as cost-no-object. Oh well, It's a good thing I love winding transformers! Hope I did not put you to sleep, Bob Carver
Q: Hi Bob- Not a very exciting question here, but I'd love to see how you package one of these amps for shipment, and I'd like to know which shipper you prefer. I hope you'll be making these until I can afford a couple! Thanks, Clay Mar-21-11
A: Hi Clay, Well, let's see. First I put some special soft cloths around each amp,then a plastic wrap around each one on top of the cloth. After that I put each amp in a box using foam corner blocks. After that, the box is then put inside a bigger box and lots more soft corner blocks plus bubble wrap is used to hold the inner box in place as well as to add extra cushioning. The whole big double box is finally taped closed and banded with nylon banding to hold the box together in case it's dropped down some stairs. Wow! At least I can describe the process faster than it takes to do it! Thanks for asking - I know lots of us want to know the answer to these important questions. I prefer UPS and the USPS. Bob Carver
Q: Hi Bob, Have always truly admired your fine designs. Your tube amp is a beaut. I hope I can afford it. I do not know yet. I now am a proud owner of DOUBLE INFINITY IRS BETAS (2 woofer towers per side) and two main speakers per side as well. I intend to use them in a very large room. The issue of course since the main speakers are very low in impedance, would you recommend the tube amp connected in series (4 ohm tap) to the main speakers or would you still go parallel (they have very nasty impedance drops to the 1 ohm areas). As far as the woofer towers I am confident with solid state. Will be running one woofer tower facing front and another facing rear (omni) with two solid state amplifiers. Since the DC resistance of the towers are 3.2 ohms each could you recommend a stable amp of your own design (solid state again) that I can use for each tower --these will have their own acceleremoters of course... Could older Phase 400 be safe or should I use something else of yours? Mar-21-11
A: H 'ster, I have owned a set of Betas - amazing speakers and one of Arnie Nudell's great and passionate works. The minimum impedance of three ohms or so is not difficult for almost any solid state amp, including any that I have ever designed. A Phase 400 would work great on the woofers. The mids and top with the Emits and ribbons are a different story though. Since they get down very low impedance-wise, we do need an amp that is happy with around an ohm. These Black Beauties will indeed make them sing. I have not actually hooked them up to a pair of Betas, but long ago I did hook up my Silver Sevens and the sound was STUNNING! I'm absolutely certain that results with these amps will be just as stunning, maybe even better. Take a leap of faith and bid happily away! Good query! Thanks for asking, Bob Carver
Q: Hello Bob, First of all I would like to say congratulations on your design and on your longevity and passion for what you do. I have had various different full electrostatic speakers for the last 25 years and for nearly all of those years, I have depended on your amplifier designs to make them sing; Phase 700, Silver 7t, Silver 9t, Signature, Signature Series II. My current system is anchored with a pair of 20th Anniversary Martin Logan CLS's and a Sunfire Signature II small chassis (Architect Series). My question is a simple one. In your opinion, will these 400watt Black Beauties have the power and headroom to make my CLS' sing? Thanks in advance for the answer, Ray Mar-21-11
A: Hi 'gunn, Thanks for making my day - I am definitely happy that you have used my designs for all this time. It seems that together we are still in the arena, even after all these years. I have loved the way vacuum tube amps sound with electrostatics, and have spent countless hours optimizing these amps with CLS's. I continue: When Martin Logan was getting started long ago, I called the founder and asked for a set of CLS's. One thing led to another, and I helped Martin Logan with financing, as well as with some design work. In the process, we two did a lot of listening with his speakers and my amps, were both influenced substantially, and the end result has been amplifiers that work hand and glove with electrostatic speakers. These Black Beauties are perfect for your CLS's! You can even predetermine just the correct output voltage easily, and adjust the Black Beauties to match as well. Great question. Hope this helps, Bob Carver
Q: hello Are you planing to built a preamplifier as good as your amps ? thanks for answering regards from France Mar-28-11
A: Hi from France', I'm not saying. Oh what the heck - yes. But not until next year. When I do build a preamp I want it to be the best sounding, the best looking, and the best there is. I know I can do it - 14 tubes (!) in the phono section alone will give it the best sound and the quietest all-tube phono in the world. Of that there is no doubt. The line stage will be designed with the help of Stu Hegeman and Tim ( I hope) even if I have to travel all the way to another world and another place to work with them. A great preamp is a huge undertaking, pretty much requiring unending devotion day and night. No sleep, no play, no Disneyland,- it's a good thing I love designing preamps. There,I said it! Bob Carver
Q: greetings do these amps produce a lot of heat? would placement/ventilation have to be a consideration thanks Mar-27-11
A: Hi'ct, I am proud to say that these amps do NOT produce a lot of heat. It is relative of course, but as an example, most big amplifiers idle their output tubes at approximately 24 to 45 watts, with 35 watts being the average for a low distortion, wide bandwidth unit. It is the idle power associated with the output tubes that makes the amp get hot. Now for the best part: the DC restorer in these Black Beauties allows the distortion to go very low and yet have the idle power at 11 watts. The tubes are so cool we can hold them without getting burned, though it IS quite uncomfortable to do it. Still, and just the same, we should allways allow some ventilation for for any electroncs with tubes. Thanks for asking, Bob Carver
Q: Hi im new to tube audio. I work alot with large sound systems and night club systems. I wanted to ask you if you worked with tube pre amps at all? I had an idea of building a tube pre amp that could have control on how much saturation or coloring the tubes would effect the sound. Do you think adding a tube pre amp will warm up the sound from CDs or computer based dj programs? Thanks Henry Mar-27-11
A: Hi '53, I like your idea of including a "color saturation" conrol to your new preamp. You remind me of me in that department, because that's exactly the thing I would do left to my own thoughts. And yes, adding a tube preamp will tend to warm up the sound from a CD or computer based system.
Q: Hello again Bob, This is Tim from Wilmington,DE.,last time we chatted you recomended me to salvage some old BOGEN amps for the quality of their transformers. While searching I came across a pair of BOGEN MO200A in good condition but had none of the 8417 tubes that they use. As you know 8417 tubes are very expensive and hard to come by especially since they require 8 8417's per amp. I know it is possible to run 6550's with a loss in power but wanted your opinion on what you would do with them if it was up to you.Would it run with KT88's or even the new KT120's. I would be very greatfull to hear your opinion. Warmest regards, Tim (mmmmcdowell@gmail.com) Mar-27-11
A: Hi Tim, Good score on the Bogens! Actually the 6550's will deliver more power than the 8417. The reason is that they pull down better (by about 35 volts) than the 8417, though they do require about eight more peak drive volts. If you installed the KT120's you would achieve even more power, using the 16 ohm tap as the eight ohm tap, the eight ohm tap as the four ohm tap, and so on. You would have to modify the driver circuits to increase the drive voltage to the grids of the output tubes, though it should be pretty easy to do. If you wanted to use the Bogen circuit, just increase the B+ to the B+ side of the driver plate resistors by about 10 or 20 percent. Then let 'er rip! hope this helps, Bob Carver
Q: How is the bias being adjusted? I see no bias pots. Mar-27-11
A: Hi'tell, The bias is adjusted by a bias pot on the back of the amp. All we need to do is look at the front panel meter and turn the pot until it reads the desired current. All six output tubes are adjusted at once by the single pot. This is possible because of the DC restorer, the circuit that completely eliminates the need for tube matching. The desired bias current is not determined by the designer (me), rather by you and the sound you want from the amp. There is no OPTIMUM bias, rather a RANGE of possible currents, all "in the green". And the choice is yours. Of course I have my personal favorite bias current, and the operating manual that come with these Black Beauties tell us what it is and expands on the concept. Great query, Bob Carver
Q: Hello Bob: I have always been impressed with your products and designs. My question: can balanced inputs be installed in the amps? Thank you, S Mar-25-11
A: Hi again my friend, Yes of course anything is possible, including balanced inputs. But I get great sound with the vintage, ubiquitous RCA inputs, and balanced does not add one bit of sonic improvement - only some convenience if you happen to have balanced cables. Balanced is extremely useful for long, professional, cable runs to help keep down hum and noise pick-up. However, for home systems, single-ended sounds best with far less complexity. A true balanced input requires an extra tube or an input transformer along with the ever-present possibility of compromising the sound because of the added complexity. Still, many folks have asked for balanced, so you are not alone. Hope this helps, Bob Carver
Q: Great looking amps. Have you ever thought about making them in mirror imaged pairs? Thanks, Robert Mar-25-11
A: Hi 'great, great name! Yes I did think of making them in mirrored pairs. Whenever I have a new idea, or don't have one and find myself stuck with my old idea, I make a mock-up of the second idea so I can try it on for size. Well, I mocked up a mirror image amplifier, put the two side-by-side, and did they ever look funny that way! At least they seemed that way to me! When two identical units were side-by-side, the whole system looked like a very serious arrangement. I liked the looks of the system better when they were the same. Great question - can't tell if I answered it though, but I gave it my best. Bob Carver Bob Carver
Q: Hello Bob,I own a pair of modified Infinity RS1's with 9 EMIMS and 16 bi-pol EMITS a total of 32 per column. I use Beta Woofer Columns with the Beta Servo control unit. Mid/high columns I use Antique Sound Lab Hurricane tube amps at 100 Watt P and 200 T. Your previous amp had P/T feature, how do these differ and would this be a major upgrade across the board. Thanks for your response. Mar-24-11
A: Hi - oops, I already answered this question. Read on. Bob
Q: Hi Bob, last time I will annoy you. I was just studying your amps and thinking to myself, what an interesting look they would present with a yellow chassis and black transformers. A big ol pair of Bumblebees, if you will. Think about it. I'm in if you put together a pair like that. Sincerely, Timothy. Mar-24-11
A: Hi '15k, Welcome back! Bumblebees - I like that! I used to build my model planes using that exact color scheme when I was a kid. Yellow wings and black fuselage. I got so stuck on a single color scheme that my little brother hid my yellow dope (model airplane paint). Well '15k, I'll probably build a yellow and black pair, but I promise not to make them HUMMMM and BUZZZZ like yellow and black bees when they are just sitting there (in hover). Thanks for writing, Bob Carver
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