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Bob Carver is at it YET AGAIN~

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Those are some pretty cheap speaker connectors for $10,000. They look like the kind you get from Radio Shack for a few bucks! That guy really knows how to turn his name into money!
 
I guess Tim and Bob don't think that is the heart of the sound. I also noticed a Radio Shack knob that I have purchased. But I bet neither affect the magic these will produce.

Hey, Elroy, where are you, North, South, East or West?
 
But I bet neither affect the magic these will produce.
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The knob of course but I would beg to differ on the speaker connectors. For an amp of that caliber there should be some sort of high conductivity copper speaker connector like WBTs or the like.
 
Elroy said:
The knob of course but I would beg to differ on the speaker connectors. For an amp of that caliber there should be some sort of high conductivity copper speaker connector like WBTs or the like.
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You hear bats talking, don't you? I envy your hearing. I really do, I'm old.
 
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bolly's gott some amps that'd give ol' carver's amps a run for their $10grand worth :)
 
I've heard these amps; they are STUNNING. And unlike many tube amps, they are NOT anemic with plenty of juice to spare.

They have a really interesting circuit that keeps the tubes at a low level when not being used hard. I think it's called the DC restorer circuit. Supposedly the tubes will last for like 30 years or so.

It's all here in the text from the auction:

Vacuum tube monoblock amplifiers 240 watts each:

Tubular Joe and I just finished building a new pair of these monoblock Amplifiers, and here they are. The story is the same; the colors have been changed to protect the innocent. I designed and wound a massive new output transformer (see picture), and we added a meter.

Adamantine Steel:

I used a new execution of my vintage, legacy output transformer design, wound on a huge, massive core made of Adamantine steel. Previously I had tried to clone them but was not successful, but after five tries I hit paydirt. More on that later.

The Heart and Soul of a Vacuum tube amplifier, the output transformer:

Yes, the output transformer. you can imagine my sadness when I ran out of the output transformers I had been saving my whole grown-up life.

I had only a single transformer left from my previously abundant stash, so I decided to take it apart and look inside, with the idea of copying it down to every last detail. I had never looked inside, and what I found was that clearly it wasn't a commercial transformer design - it was way too good - it just had to have been wound for the military. It was that amazing inside. It was "pie" wound with many separate pie windings, a vintage winding geometry that is not used today; it's way too expensive, is a true art form, and besides, it is not needed anyway. The science of steel, in the vast gulf of the intervening 50 years or so has been developed to a remarkable degree. Steel today is not what it used to be; it is a zillion times better - less hysteresis loss, far greater magnetizing inductance, and vastly improved immunity to saturation. Today, great transformers can be easily "layer" wound, and by using modern steel, superb performance may still be abtained. Just the same, I copied the pie winding geometry down to the last detail, but was unable to locate any vintage "iron" (steel actually). So I had to use modern steel. And guess what happened! Well, I for one was not prepared for what happened next. Losses dropped to almost nothing, power response went through the roof, and the power bandwidth increased by about half an octave! I stepped back from my laboratory bench, and looked at the thing wide-eyed, scarcely believing my measurements. Not only that, but I found the maximum power output had increased by eighty watts. And here's the best part: they sound the same, exactly the same as my original output transformers did. I feel LUCKY! The pictures show me hand-winding the new output transformers, and the end picture shows the finished transformer. It sure is big!

Tim de Paravicini and me:

It was three summers ago that Tim de Paravicini and I met in a small town (Sebastopol) in California. We spent three fascinating days discussing vacuum tube power amps and the magic of our mechanical vinyl recording system that somehow, against all odds, is able to deliver music with life and romance that no other system can.

We talked about output stages, phase inverters, front end amplifiers, output transformers, and especially the dynamic characteristics of tube amplifiers playing music.

I will never forget those fascinating three days as long as I live.

We mused that there have been only four basic designs that have been widely used since the very beginning; the Williamson circuit, the Mullard 520 circuit, the Dynaco pentode-cathodyne circuit and the Stewart Hegeman all pentode circuit. As the mornings turned into nights and we used up all the napkins on our table drawing amplifier diagrams, a remarkable circuit emerged as Tim held the pen and drew a balanced current-sourced front end, followed by double balanced drivers using a frame grid triode ultimately direct coupled to the grids of the output tubes.

The man with big muscles holding the amplifier is me, Bob Carver.

Successful collaborative effort:

Tim designed the all important current sourced front-end. Together we designed the output stage, power supply, bias supply, and I designed the driver stage using the frame grid triode. It’s simple, magically balanced with no offsets, and as it turned out, sonic performance that cannot easily be believed.

But I'm getting ahead of myself.

I've been collecting vintage amplifier parts for a lifetime, always with the notion of making a small museum someday. But after spending three fascinating days with Tim, I had a change of heart and decided a much better use for them would be to build an amplifier. And here it is.

There's more.

Every vacuum tube amp in the world suffers from shifting DC operating points, and this, unfortunately, has remained a functional limitation and maddening sore point for amplifier designers ever since the very beginning of vacuum tubes. Consequently, I had to invent a DC restorer circuit using a 6AL5 / 5726 tube; it eliminated every last vestige of DC shift, while simultaneously reducing distortion three-fold and vacuum tube idle power by the same amount. As Tim would say, "Nothing new under the sun", just the same, it's never been done before, and it works flawlessly.

Of the four circuits mentioned earlier, the Mullard 520 circuit is used in Marantz (8B and Model 9) amplifiers, as well as countless others by McIntosh, Eico, and Citation. Heathkit used Williamson almost exclusively, and Dyna used the ubiquitous cathodyne circuit as did hundreds of others. Citation, Lafayette and RCA always used the Hegeman circuit in their best, most expensve units. And that was it! Only four!

This amp uses all vintage parts except for paint, the chassis and some of the small circuit parts. Even the transformer covers, tube sockets, and transformers themselves are vintage. The front end is a Telefunken 12AX7, the tube following is a five star military driver, and the DC restorer is a JAN 6AL5 / 5726. Output tubes are Vintage Carver Silver Eagles, double tested, burned in for six weeks and tested again. The best of the best. All are NOS except the Telefunken. The transformers are MASSIVE vintage iron; each mono-block amp weighs in at 42 pounds, 84 lbs in all. Power is an easy 240 watts rms with a power bandwidth from 18 Hz to 47 kHz, frequency response 2 Hz to 85 kHz, and distortion less than 0.15 % at 240 watts out.

This amplifier has been designed with big Apogees in mind, the one ohm kind. It delivers 362 watts into my one ohm Apogee Scintilla – I included a one ohm tap on the output transformer. Actually, my vintage transformers have always had the tap. And the mighty KT88’s do it with aplomb.

It's been so over designed that I expect it will last at least 50 years without need for service. In twenty years the front end and driver tubes should be replaced, whether they need replacing or not. Here's the best part: even the output tubes should last 50 years unless they have an unforeseen catastrophic failure. No need to replace them unless they won't bias up.

The sound:

This amplifier stands with a small handful of the world's great vacuum tube amplifiers.

And beyond:

It's elegantly balanced, possesses huge energy storage that vintage designers (many of whom were geniuses) could only dream of, a DC restorer, and twelve output tubes in all. Nothing can touch it.

The features:

Four output terminals, ground, one through three ohms, four ohms, eight ohms. A bias control that sets idling current. A switch that changes the feedback from classical (vintage) to contemporary.

Front panel meter:

It has a front panel meter that performs four important functions: It is used to set the bias, it’s part of the built-in tube tester that allows the output tubes to be tested under actual voltage and current conditions, it allows the output tubes to be matched, though that is quite unnecessary, thanks to the DC restorer. Finally, it doubles as a VU meter, and is fun to watch, more fun than most, as it responds to output current rather than output voltage.

This amplifier has built in auto-balance, and a volume control. A power switch with turn-on inrush current limiters is also included. And finally, a chrome roll bar for the front end tubes.

Tim designed the all important current sourced front-end. Together we designed the output stage, power supply, bias supply, and I designed the driver stage using the frame grid triode. It’s simple, magically balanced with no offsets, and as it turned out, sonic performance that cannot easily be believed.

This amp was lovingly hand crafted by Joey “Tubular Joe” Bonin, the best tube amplifier builder and craftsman of all time right here in the rain forest of the Pacific Northwest.

Hi, Tubular Joe here. Just wanted to let you know of a few aspects and features of these amplifiers. They are hand-wired, point-to-point with star grounds. The tagboards are military-style epoxy with bright silver-plated swaged turret terminals.

The transformer covers are lined with 3/16" thick sound and vibration-deadening panels.

Hope you like them. Enjoy!

Bob here. If one ever breaks, as long as I'm alive I'll fix it free if you get it to me. Even the tubes. One last thing. I will autograph the amp to you with your name on the champagne gold escutcheon. Example: "To our friend Skip - Enjoy the music! Bob Carver". Except your name, not Skip's, of course. Or anything you would like. If you wish. Your choice.

One more thing, I accept any form of rational payment, and shipping is about $100 dollars for both.

FRAUD ALERT

Several fraudulators has down-loaded my entire auction and posted it on several sites around the world, EVEN including eBay. Now I have sort of become used to people copying me from time-to-time, but this is almost bazaar. They have copied my text and even a photograph of me! To be sure it's really me, ask a question that only I would know the answer to - like my dog's name or a science question. This auction is real, as you can verify my eBay name "Audioshopper" in the upper right of this opening auction page.
 
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Grainger49 said:
You hear bats talking, don't you? I envy your hearing.
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I HAVE performed upgrades on various equipment with better speaker connectors, wire etc. and indeed I DID hear a difference.

Point is, if a company is going to set out to make a truly cutting edge amplifier- why skimp and place a weak link in your chain for a cost difference of $50? So that your profit will be $9,000 instead of $8,950? Doesn't make sense to me. Those speaker connectors it looks like he used are nickel plated "metal". The conductivity of those in comparison to high quality connectors is much less to a point that it really does degrade the audio signal and yes, you really can hear the difference and no, I do not hear bats talk :rolleyes:
 
Here's the latest Q&A from Bob's sixth set of tube monoblocks with meters. This set sold 5/12/10 for $7500, a full 25% less than the previous identical pair. There's not much new information revealed this time but this pair Bob designated at 240 watts compared to all the others listed as 180 watts. Again, due to the nature of the way eBay builds it's web pages you should start at the bottom of the post and read upwards to follow chronological order. This is the first of 2 posts encompassing the full Q&A. Enjoy!

Q: not a question but a comment on your amplifier. they are certainly built with quality parts but the photographs of you manufacturing your transformers indicate,to me, that you are just having fun doing this. unfortunally i am not in a financial position to bid. i hope you are doing this for a while longer. i certainly would like to bid on a pair of these when my ship comes in. May-03-10
A: Hey 'mon (70's expression), there is no doubt in my mind that you will someday soon be able to bid high and win. In the meantime, keep on thinking about amplifiers as there scant few dreams that are as much fun or sustaining. I do enjoy winding my own transformers, and painting the chassis in my upstairs paint-booth bathroom. I intend to keep on doing this for a long, long time. Bob's my name, and amps are my game; I could not stop if I wanted to. Bob Carver
Q: Hi Bob, Let me state for all would-be bidders that this auction is truly from the real Bob Carver. I have the pair from Carverfest so I should know. But now I have to ask how you manage another 60 watts RMS without adding another pair of KT88's. I read below about the 1 ohm spec of 370 watts and how it takes advantage of your DC restorer circuit, but is your new 240 watt spec at 8 ohms? It makes we want to upgrade! Best of luck on this auction to you, Bob. cheers weitrhino May-03-10
A: Hi 'rama, Yes, the 240 watt specification is an eight ohm spec. And at eight ohms, the amplifier output tubes are loafing, operating at about 62% of maximum capacity (110 + 20) x 3 = 390 watts, and 240 is 62% of 390. An upgrade would give you more power, but not any change at all in the sound. Thanks for writing in with a cool question, one I should have addressed in the auction. Hope this helps, Bob Carver Hope this helps
Q: As there seems to be some question of Authenticity, will you please verify this auction by answering this question for me. - Aside from a pair of these beautiful amplifiers, what other item did you give away in a raffle 2 years ago at CarverFest in North Carolina? Thank you for your response. Ed May-02-10
A: Ha! Thought you had me, didn't you? It was a pair of my Sunfire Cinema Ribbon loudspeakers, the ones that got a mind-blowing review by Robert Harley in The Absolute Sound. Wow! I sound like a pitch-man, don't I? Oh well, I can't help it. Bob Carver.
Q: Hello Bob. Is it possible to have both you and Tubular Joe sign these amplifiers should I win? Hope to hear from you, Kevin May-02-10
A: Hi 'tvr-1, no problem. However you should know that Tubular Joe has poor penmanship. Just kidding! We will inscribe anything you desire, in gold, on the shiny black output transformers. Bob Carver
Q: Hello Mr. Carver. I live from Italy. Please tell me it is possible to ship to Italy, and cost. Andrea Croci May-02-10
A: Hi Andrea, yes I can ship to Italy, and the cost would be about U.S. $350 dollars. Good luck! Thanks for your interest. Bob Carver
Q: Would you mind telling me your dogs name? There have been quite a few bogus auctions on eBay lately, and I like to make sure you are really Bob Carver. Thanks. Bill May-02-10
A: Hi 'olt, It's Zeus. He is a small, black British water spaniel with more love than all the amps in the world. Even 240 watt red ones. He has a BIG name though. Thanks for writing, Bob Carver
Q: Greetings Bob, I am very curious to know how you get so much power from this amplifier at 1-Ohm? Thank you for your time, Thomas in Texas. May-02-10
A: Hi Thomas, Great question! Easy. Well, maybe not so easy; we have to realize that the mighty KT88 is rated for 110 watts rms audio per pair. Additionally, each tube is rated for 42 watts of plate dissipation(at idle), and most vintage amplifiers operate with the idle dissipation at about three fourths max, or 32 watts per tube. Now thanks to the DC restorer, this amp idles at only 9.75 watts per tube, and about 60% of the remainder becomes available as output power. So we have 110 + 0.6 x 22 watts = 123 watts per pair. Finally, three times 123 = 370 watts total. Thanks for asking a great question, Bob Carver
Q: Q) Who was the Australian importer when the AL111 was in prodution? Nun_ _ . from Pr_ _ _ . Just looking to verify authenticity. (Hope you knew) Regards, Steven. May-02-10
A: Hi '87, I can't remember, remember I was old when Atlantis sank, and it was twenty years ago. Besides, you're supposed to ask me something I know the answer to, like my dog's name. I remember that! Thanks for the fun moments, Bob Carver
 
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Part 2:

Q: Hi Bob, I have a quick question. I have a Carver M 4.0t Silver Seven Vacuum Transfer Function Amplifier with a Carver C 16 preamp and hi-end Audioquest interconnecion cables. I'm also using your Loudspeaker Control System I usually play classical and jazz music. What kind of speakers do you recomend for my Carver system? What are my options. I have a pair of Bose 502 and it sounds rather dull. Thanks For Your Time Jorge Hernandez Pismo Beach, Ca. May-11-10
A: Hi '123,Check out my Cinema Ribbon loudspeakers. They were reviewed by Robert Harley in the Absolute Sound and received an incredible review that manufactures normally would die for. Even me. I designed them to have a big soundstage with pin-point imaging within that big enveloping acoustic. Google Absolute Sound and search, or go to the Sunfire web site. I promise as my name is Bob Carver, these speakers are just the ticket for your classical and jazz. Thanks for writing and for the question, Bob Carver.
Q: -Hello Bob, I have been a fan and happy listener of your incredible insanity from the moment I purchased a new M400 cube amp years ago. Today I have a pair of A760x amps, a C-19 preamp, and a SD/A 490t CD powering a pair of KEF 207/2 reference speakers. My question is this - being unable to muster the mojo to purchase the recently offered pair of Silver-7 tube amps, I am wondering what the audible difference would be if I purchased these tube amps for auction and used them in place of the a760x's.... less power for sure, but honestly I have never owned a tube amp so it is a mystery to me ... any thoughts you could share? Thanks for your time and many years of happy musical experiences. -Gary May-11-10
A: Hi '6b, Ummm ....your eBay handle sounds like a tube amp. If you have never owned one (a tube amp) before, you are in for a real treat. Once we have experienced a tube amp , we can never go back. As for the power, tube amplifiers sound as if they are about half again as powerful as their power rating would infer. There are a variety of technical reasons for this, but just beyond beyond the scope of my short answer here. Still, it sounds as though you are getting some great sound. Thanks for writing, hope this helps. Bob Carver
Q: Hi Bob, Unfortunately, I am over loaded with amps at the moment (9 or 10 I think)or I would give these a whirl. I would like to ask you: who you would recommend to service my vintage tube ARC D-79 amp in the Seattle area? I live on Bainbridge Island. I thank you in advance for your reply. Kind regards, Bill Roberts May-10-10
A: Hi Bill, No sweat, bring it into Rita's Vintage Audio Shop in the old Sunfire factory right here in Snohomish. Bill Flannery is the vacuum tube technician and we work side-by-side on the vintage tube amps and pre-amps on weekends. Bainbribridge is about 35 minutes plus a fun ferry boat ride from Snohomish. Thanks for writing, Bob Carver
Q: Hi Bob, It is so cool to see you building tube amplifiers! My name is James. I used to work for Carver from 1989 until 1998. I worked for Sunfire from 1998 until 2007. If you ever decide to go into production again building amplifiers or audio equipment, I would love to work for you. I am very good at all kinds of mechanical assembly and soldering work. In fact, in the final days at Sunfire I built the last of the true American built Sunfire amplifiers from start to finish. I am a very hard working and efficient assembler, with great attention to detail and a true commitment to quality. Those tube amps with all that point to point work look like they would be very fun to build! Please give me a call if you are interested in my help. Best Regards, James Keener (425) 346-4856 May-10-10
A: Hi James, I just answered this. Hi again! Boo! A friendly ghost. Bob Carver
Q: Hi Bob, It is so cool to see you building tube amplifiers! My name is James. I used to work for Carver from 1989 until 1998. I worked for Sunfire from 1998 until 2007. If you ever decide to go into production again building amplifiers or audio equipment, I would love to work for you. I am very good at all kinds of mechanical assembly and soldering work. In fact, in the final days at Sunfire I built the last of the true American built Sunfire amplifiers from start to finish. I am a very hard working and efficient assembler, with great attention to detail and a true commitment to quality. Those tube amps with all that point to point work look like they would be very fun to build! Please give me a call if you are interested in my help. Best Regards, James Keener (425) 346-4856 May-10-10
A: Hi James, Sure is fun to hear from you - a nice blast from the past. I have a day job at Sunfire, so I work on these amps in the evening and on weekends, and Tubular Joe builds them when he has time. About eight amps per year. A complete labor of love for us both. Still, perhaps we could build some more if you pitched in - I remember your build quality was extraordinary! Even remarkable and amazing - you were a perfectionist's perfectionist. Let's talk ; call me after the auction is over if you come up for air and if you can. I'm looking forward to talking. All my best, Bob Carver
Q: HI BOB ¡¡ I HOOCK THEM UP ¡¡ They sound GREAT... ever so sweet " Maravilloso" , Im so Happy , great packing to¡¡ they arrived in perfect shape.. sending pics check your mail THANKS FOR ALL May-09-10
A: Hi '816, You won my earlier auction! They arrived safe and sound - a long journey, and they work. GREAT, ever so SWEET. I'm happy when you are happy. Happy Birthday, even if the earthquake delayed their arrival. All's well that end well. Thanks for letting us know, Bob Carver
Q: Bob---I just found a fraudulent amp auction and put a huge bid on it. Thought you'd want to know. May-09-10
A: Yes I saw it too. And I outbid you. I put a bid of $100,100 dollars. I cannot believe that eBay cannot take this down, but so far they have not done so. They are trying, but said it takes up to 24 hours. It is a one day auction, so that will not help. The real damage is that persons who send them $2000 dollars will certainly lose it all. The good news is you can tell it's fraudulent by my huge outrageous bid! Thanks for letting us know; It help us all. Bob Carver
Q: Hi Bob, Your favorite fraudster is at it again. lol he doesn't give up. 320529753027 May-09-10
A: Hey Man, you gotta be kidding! Guess not. Okay, I'll contact eBay, inform them of the fraud, and ask them take it down. Thanks, Bob Carver.
Q: Hi Bob , Steve here in Washington...I have a question about you sunfire pre amp . the Theater Grand Processor II .....I also have a Sunfire 300~2 amp....On the back of the amp , it has Lab and regular inputs...In the manual , you said to use the Lab if there is no DC output from the Pre....Would it be safe to hook up the Sunfire Pre to the Lab input of the Sunfire amp...And thanks for your time Bob... Steve May-09-10
A: Hi 'op, Yes it it is safe. The Sunfire has a giant, and I mean a truly huge film output coupling capacitor just to make sure! Hope this helps, Bob Carver
Q: one last thing i just bought 2 pair of your CRS-3 speakers and want to use one or both pm-900's to design some variable subwoffers to compliment them, so if oyu have any spare ideas or thoughts i could use a few good part names to use in the build. randyhart420 May-09-10
A: Hi again, Any high quality modern part set will work beautifully. There are many to choose from; you can't go wrong with any of them. Honest. Good luck! Bob Carver
Q: hi Bob: it is me your problem child again. during the last auction you said you would ( after getting back from being out of town) you would hook my old disabled rear end up with the schematics, parts list and the places to get those impossible to find parts for the amps. i also wanted any recomendations for upgreding the a760X and pm900 as i have two of each. and now i am on disability retirement because of exposure to some bad chemicals at work i would like to tear down the amps and upgrade the resistors and capacitors(your recommendations) of course (not every single little res. or cap but the most affecting ones then try to build on of these because at 10 grand a pair it will be the only way i can own them. i would be graetly appreciativeam going with this one again my email is randyhart429@hotmail.com phone 909-213-4920 i know i am reaching but you are my hero and have been since a m1.0 drove a set of klipsch korners to the brink in 1999. randyhart420 that is ephesians 4:20 May-09-10
A: Hi '420, I'm glad you wrote in; I have a character flaw - I procrastinate too much. However, I'm working on the updated schematic and a parts list for you. I'll have it done next weekend. Do you have schematics for your Carver amps? Stand by my new friend, Bob Carver
Q: HI BOB Finally got my hands in your amps¡¡¡ Boy are they beautifull ¡¡ Im shure they will sound " maravilloso" Great. Thanks a lot I going to plug them sunday nigth One simple question are they 220 volts as we requested ?? Best regards from an "honor full " fan May-07-10
A: Hi '816, They made it! All the way to Chile. One ship, four planes, three trucks, one taxi! Not to mention an earthquake. Yea! Bob Carver PS: They are 220 volts.
Q: Bob, Sorry to use this format but this is what is available. 37 years ago I met you at a stereo store at Northgate when you told me how to add caps to minimize distortion on an Ortofon cartridge. I asked the owners who you were and when I found out, asked if you had any jobs. You sent me to see the VP (Steve?) at Phase Linear and I was hired to be a tech, specifically QC on the amp line. It was the best company that I have worked for. You know how to treat people/employees and taught me a great deal. I have followed your career and tried to see you a couple of times in other time zones but was out of town or unavailable. So thank you for taking a chance on a fairly disoriented Nam Vet and for giving me a life opportunity. I wish I had the coin for these puppies you are selling. I wish you all the best. Joseph Westphal May-07-10
A: Hi joseph, I remember that day - it was North west Audio and they carried Ortofon. It was long ago - we were young kids back then and here we are today still in the arena with the music playing on. If you ever make it to my time zone, look me up at Sunfire and let's have breakfast. I wish YOU the best, thanks for taking the time to write and for remembering, it has meant a lot to me. Warmest and best regards, Bob Carver
Q: Bob, I purchased the set of amps at the end of January and promptly became consumed with business travel and work, trying to keep my business interests alive in this awful economy, so sorry for lack of communications since. However, I wanted to tell you that I've finally had the chance to audition the Chery amps with Infinity RS1's, Gama's, Beta's, Sigma's and Epsilons; Sourced by both vinyl and CD's. As you may recall, my comparison amps include McIntosh 1201's, Onkyo M-508's, Silver 7-t's, TFM-45's & 55's and some other fine amps that I enjoy including some tube units. So the bottom line is simply that the Cheery's, as I like to call them, are truly astonishing. I was wrong to have doubted their ability to drive such power hungry speakers and the result is incredible. We've experimented with the feedback and like 'Classic' best. So thanks much for bringing these to life and keep up the good work! Hope many others can enjoy the beauty of your fine work. May-07-10
A: Yea! Me too! Bob Carver
Q: Bob. I don't get along to well with computers and email I can never figure out if a message goes throgh using this ebay route. Did you get a message concerning dc restorer in two stages the secong beginning with OOPS? neal May-06-10
A: Hi 541', Nope. I did get it the second time you tried. Don't feel funny though - I too can barely turn my computer on - at least that's what my daughter thinks of my computer skills. I deny that of course, and tell her I'm a computer expert. Bob Carver
Q: Not a question Bob but I want to let you know I how have the second amp finished am am listening to two now instead of one, that I built from the schematics that you sent me, It' up and performing and I must say I think I might have gone to Heaven!!! I have been running the first one while I was building the second one and yes two are twice the sound as one. I have been playing a CD of The US Navy Band and The Sea Chanters and I am hearing sounds that was never there before. Bob I thank you for your encouragement. I don't have words to describe what I am hearing when I listen to my amps. Investing in a pair of your amps is a better investment than the Stock Market, stocks go down the value of your amps go up. Thanks again Bob. Your Friend, "jay" May-06-10
A: Hi 'music, I love it that you don't have the words to describe what you are hearing when you listen to these amps. But you do - you said you went to Heaven!!! Just don't die first. Thanks for taking the time to write 'music (Man) - means a lot to me, Bob Carver
Q: Hi Neal again. Maybe my question on the restorer didn't go thru. I will try again. If I recall the idle per tube as about 12 ma, right? Now if the amp is ramped up to full out put with still no waveform distortion, and the signal induced current could be magically stripped away leaving just bias current, what would this current be per tube at this level, with the dc restorer operating? cordially neal May-06-10
A: Hi Neal, I can tell you have been thinking a lot about the DC restorer. Your question is deep and very sophisticated - here is the answer, but first a thought experiment. Imagine a standard class AB tube amp with each tube biased such that each tube is dissipating 43 watts at idle, idling along at 70 mA. Now we drive the amplifier to full output, say 75 watts and measure the DC value of the cathode current with an ammeter. We write it down. Back to idle. Now we turn the bias control all the way down (max negative bias voltage) to say five mA. We again drive the amplifier to maximum output, 75 watts. We once again measure the DC value of the cathode current. What do you think the cathode current will be? We find that it is almost identical to the current that existed when we operated the amplifier at maximum quiescent dissipation! In other words, the large drive level acts as if it strips away the high idle current. This is an astonishing result, is hard to believe, is non intuitive, AND it is the TRUE nature of a class AB output stage. The DC restorer mimics that nature, except of course on the low end of the output tube dissipation. It works because the crossover distortion (eliminated by idle current) occurs at the zero axis crossing, NOT at the peak of the output waveform or anywhere in between. During the crossover period, a well designed output stage is operating in pure class A and with AB symmetry, hence zero distortion. The DC restorer allows the output stage to operate instantaneously in class A during crossover, but not at large outputs where it would only make things get hot at idle. Remember, at small output levels, class A does not require much current at all. So, as you can see, the answer to your question is 12 mA. This is such a difficult concept to understand and get our arms and mind around, I can see why nobody ever did it before. I got lucky, but only after banging my head against several sliding bias schemes, which are easily understood. Bob
Q: Hi...I have been looking up information on "pie winding". Now that i have wrapped my brain around the principle, tell me, how many primary and secondary sections are in those transformer? Neal May-06-10
A: Hi Neal, I'm not saying, it's my secret. However, "The Radiotron Designer's Handbook" published by RCA has an extensive chapter on winding geometry. pages 1205 and 1206, as well as the chapter beginning on page 210. Inspect fig 5.13E on page 213; you will see a pie winding chart showing thirteen sections for a very expensive output transformer. The chart also shows inexpensive transformers with fewer sections, all the way down to only two. There is a great DVD available on eBay called "Audio Transformer, Design and Construction". It contains 24 (!) complete books written by all the great transformer designers from the very beginning through the almost present time. I don't remember the item number but you can find it. Hope this helps. You are going to have lots of fun on your transformer adventure - I just know it - I sure did! Hope this helps, Bob Carver
Q: Hi Bob My question is not about this auction,although I would Love to own these amps,bob I have a collection of your amps,and the last one I purchsed was a lightstar reference,I always thought it was the last amp you designed before leaving carver corp.can you tell me how of your design is in this amplifier? thanks David May-05-10
A: Hi David, It was indeed the last amp I designed before I left. I had designed and finished the first prototype, and it was my colleague Vic Richardson who completed that work by putting in the finishing touches and preparing it for factory production. A major undertaking. Vic and I have worked side by side forever since Carver was started, and he currently works in the engineering department with me at Sunfire. The Lightstar circuit with its tracking power supply became the tracking down converter and my first Sunfire amplifier. Bob Carver
Q: Hey Bob I'm a big fan currently use Slver9T with a carver sonic H C-3 , and a great pair of your ALS111 ribbon speakers. Had it all for about 14 years works flawless,Crystal clear sound and affordable,Thank you May-04-10
A: Hi '3765, I love it! Man, you are making my day, I enjoy hearing that my designs have been a powerful force for good in peoples lives, and that the music plays on after all these years. Fourteen! Thanks for taking the time to write, it means a lot to me. Bob Carver
 
Plastic speaker connectors? What else is he skimping on? I'd want gold plate all round for that money, including the paint job.
 
For that price, it better be easy on tubes, be built conservatively, and better come from a certain company in Binghamton, NY (hint, hint). And it better not be synomynous with Fire! :tresbon:
 
KentTeffeteller said:
For that price, it better be easy on tubes, be built conservatively, and better come from a certain company in Binghamton, NY (hint, hint). And it better not be synomynous with Fire! :tresbon:
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Yeah, really. :yes: I was surprised to see how much effort he seemed to put into the design but I did not like seeing such basic terminals and switches. I'm sure it sounds great, but when you're going to go through such great lengths to build an amp, take those small items to the next level.
 
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