"NOS" Vintage amp by Bob Carver/Tim Paravicini

sleepysurf · Aug 21, 2008

For those who might have missed this, Bob Carver and Tim Paravicini recently designed a one-of-a-kind set of tube monoblocks, crafted mainly with NOS vintage parts, and auctioned on eBay. It sold for $5,800. Their description, and ensuing comments are still online, and definitely worth the read...
[URL="http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=180275596145&ssPageName=STRK:MEWA:IT&ih=008"]http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=180275596145&ssPageName=STRK:MEWA:IT&ih=008[/URL]

Cherian · Aug 21, 2008

Bob donated one set of these amps to carver fest. It will be raffled off so all you carver fans may want to think about going to the Carver fest this year. Attached is a link.

This is the second set Bob has sold on e-bay. The first sold for over $6,000.00

http://carveraudio.com/phpBB3/viewtopic.php?f=31&t=5691[/url]

C.A.P · Aug 21, 2008

Another great produced by Bob Carver. !:rocker:

TomDac · Aug 22, 2008

Here's a perfect example of why links to ebay auctions are not allowed. Once that ebay link is dead, this thread will become worthless and that's a shame because it's a great read.

Here's the text from the auction:

Vacuum tube monoblock amplifiers 180 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 names have been changed to protect the innocent.

The man with big muscles holding the amplifer is me, Bob Carver. In addition, it is I, the man with the sandwich.

It was two summers ago that Tim de Paravicini and I met in a small town 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.

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.

If you're still awake, read on.

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 often used the Hegeman circuit. 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 General Electric 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 180 watts rms with a power bandwidth from 23 Hz to 45 kHz, frequency response 2 Hz to 85 kHz, and distortion less than 0.15 % at 220 watts out. Power at clipping is 225 watts. Even more into six ohms.

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 or two ohms, four ohms, eight ohms. A bias control that sets idling current. A switch that changes the feedback from classical (vintage) to contemporary. A jack for the bias meter, though with the DC restorer it really never needs to be adjusted. It has built in auto-balance, and a volume control. A power switch with turn-on in-rush current limiters is also included. And finally, a chrome roll bar for the front end tubes.

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. Except for the tubes. One last thing. We will autograph the amp to you with your name in gold. Example: "To our friend John - Enjoy the music! Tim de Paraficini, Bob Carver". Except your name, not John's of course. If you wish.

TomDac · Aug 22, 2008

Q&A from Ebay auction.

Question & Answer
Q: Hello Mr. Carver, kudos! Nice product! Do you think this amp design will ever be available for purchase on a limited scale, with modern day equivalent parts? Kind of a direct order scenario? Aug-19-08

A: Hi '-old, Thanks for the kudos! It's a new day and that helps makes my day! I have no plans, none at all, to build these amps with anything except vintage parts from my museum. Great question. Thanks for asking, Bob Carver

Q: Hi Bob. Could I get a copy of that DC circuit later? Email is [email protected] I have some spare Acrosound TO-330s that might work with it. Thanks for everything. Regards, Bob Gravlin Aug-19-08

A: Hi Bob, you carry a good name. And yes, no problem with the DC restorer. Bob Carver

Q: Hi, Tell me more about the output transformer What brand or general description ext. Very nice amp. Thanks Bernard Aug-19-08

A: Hi Bernard '081, This output transformer has a remarkable bandwith, and the reason I know how good it is, is that it was fairly easy to get the feedback around. Power response extends well beyond 20 kHz. As for the brand, I would tell you if I knew; I've had them in my stash for over 25 years, and for the life of me, I cannot remember what brand, no matter how hard I try, and they are unmarked. I've had them ever since my undergraduate days in college, always keeping them with me in the trunk of my car whenever I moved. I think I loved them more than my girlfriend. Good question, thanks for asking, Bob Carver

Q: Hi Bob, thanks for the explanation. I nearly get involved in a class A2 amp. I am glad I did not go for it. By the way Australia main voltage is 240VAC / 50Hz. Please let me know if I can bid with a 240v version. Tks Aug-19-08

A: HI, You are very welcome. And yes, this amp has a dual primary so it can be operated on either 120 volts or 240 volts. Thanks for asking, I forgot to mention it earlier. bob carver

Q: Hi Bob , wow what a wonderfull amp once again.....!!!..I have 2 questions..1..do you have a shop or retailer here in the Northwest..and 2..I just bought a used pair of your AL -III speakers with the cross overs..my question is how many watts per channel can they hold..I want to mono block my 2 Parasound HCA-1000,s (rated 400 watts each into 8 ohms,s)..I cannot find any where on the net a mannual for these speakers...Thanks for time... steve , Tacoma Aug-18-08

A: Hi Steve, Let me do a bit of research and get back to you, but please remind me next week to make sure I don't forget. Your missive sure brings back long ago memories! Thanks for writing, Bob Carver

Q: Hi Bob, Greetings from Canada. I have owned many of your pieces but unfortuneatley this lated work of art from you is beyond my reach. I do have a question to ask, if anyone would know it would be you. Ebay item # 140259226660 I just listed a pair of custom built KT88 Mono blocks (Not Bob Carver knock offs by no means) The builder as it turns out did not use the correct output transformers so there is distortion as you turn up the volume. I have had 2 people look at these and both have come to the same conclusion. I might be inclined to end my auction if I could get my hands on a pair of output trannies that would do the job correctly. With the people you know could you put me in touch with someone who would want to part with a pair of Old Stock. I am leary of using any of the new overseas stuff being offered online. Any trouble shooting or thoughts would be appreciated as well. Thanks for your time and any input. Aug-18-08

A: Hi 'forall, I love your handle. I'm afraid I hold a different view. It would be almost impossible that the output transformers are at fault. That's because the KT88 is the biggest output tube there is, and the reflected turns ratio of any rational transformer would not be such to over-load the tube. In the other direction, any distortion would actually go down. Plus, the chances of having TWO outputs be bad is almost zero. If you e-mail me your phone number after the auction is over, I'm pretty sure we can get to the bottom of this by going over it on the phone. We'll solve it. Looking forward to having a scientific discussion about amplifiers with you, Bob Carver.

Q: HI. I would like to know what class mode it is ? Push pull, triode, ultralinear and etc. and excuse me for being dumb. Do you ship to Perth Australia.. Thank you ,,, Hsrry Tan Aug-18-08

A: Hi'6059, I love questions like this 'cause I get to be a teacher again. Stay with me, sit back and enjoy the ride, and know that your question has a deep and technical answer. I begin. This amp is push-pull class AB. It is not ultra-linear, nor is it a class A triode. Class AB is called AB because the amp is like both sides of the same coin both, operating sometimes in class A and sometimes in class B. In the old days (vintage days), amplifier designers operated the output tubes with lots and lots of idle current in order to keep the output tubes in class A as long as possible. The solution was to run each tube at about 50 watts plate dissipation. Hot, hot hot!(Citation II power amp) with 33 watts being an average. Still too hot. Sometimes the plates would glow cherry red! And that was accepted; the amp ran in class A much of the time, keeping distortion well under one percent. Tubes were inexpensive back then so it didn't matter if they had a somewhat short life. For example, a 60 watt amp would stay in class A up to about 12 watts, then smoothly transition to class B for the rest of the way. If the tubes were operated with longer life in mind, class A would be good for about two watts. Running expensive output tubes that hot didn't seem like a good deal to me, so I invented the DC restorer to fix this problem once and for all. It allows class A operation up to about 108 watts rms, while at the same time keeping idle dissipation below 11 watts per tube. Back to Ultra-linear. I prefer that output tube screen grids be operated from a second, or regulated power supply than driven from an ultra-linear tap on the output transformer. Two reasons: when the output tube plate is pulled low by a powerful audio signal, the ultra- linear taps drive the screens so low that the output stage cannot deliver enough current to drive a difficult loudspeaker load. Operating the screens at a fix voltage competely fixes the problem, and avoids high voltage on them at idle. Safe!

Q: hey mr carver, will you talk me through putting them back together if i win, i doubt i will. lots of action from people who know a lot more then me. dad was a ee with bell labs for 38 years. watched him build his tube amps from scratch when i was 7 that was a 1961. they got trashed in a move in 73 . he passed this year would love to have them for just rememberance. sounded good too with the folded horns. i still see them hanging in concert/musical halls at the top corners of the stage. by the way, i have a 4.0t i love and all those 500t's they look as good as they sound. i love the old phaselinear s and the bestlooking blue meters on the mac's i know they are mostly for show but they look "cool" should i win, will you advise on a setup for the total system that i might be able to afford. i have a duak turntable and a denon table with sure and garrad pickups. i reacted without thought your name says it all. silver sevens were 19k each if i remember right. how do these compare? Aug-18-08

A: Hi tags, Your handle reminds me of an Al Cappy Lil' Abner character by the name of Joe Blfplk. Cannot be pronounced! Your adventures sure do take me down Memory Lane.My first amps were tube amps too. Had a pair of 50C5's, a 35W4, and a pair of 12AX7's. Anyway, I will help all I can. A BIG thanks for writing in and a big thanks for bidding. How do they compare? Well, that's sort of like asking a parent which child he or she likes best. Too hard that question! They both sound great, like life. Bob Carver

TomDac · Aug 22, 2008

Q: Mr Bob... to get a mass product for your FUTURE... is it possible to ORDER to a factory to product the "NEW" Tubes..??? rather than CANIBALized the Old Amp...? > Go to CHINA for the IN-EXPENSIVE Labor ??? But Be FAIR TRADE PLEASE... they are HUMAN also...! I REALLY REALLY hope that you continue your DREAM MUSEUM with all those OLD ANTIQUE Amplifier. So the next Generation can learn from their heritages... Of course your Wonderful Creation will be the Master Piece in your original DREAM Museum. Please think about it ! I take a deep bow to honor the beatiful Mind and Beautiful Design for Both of You... WONDERFUL Team Work !!! BRAVO !!! MAJU TERUS ...!!! = Move forward ...!!! ThankUVmuch PEACE, moonear. a JAVAman in Minneapolis not the Englishman in New York. he... he.. he... Aug-18-08

A: Hi 'cat, Yes it is possible to go to China for the tubes and labor, but Tubular Joe is the best there is, and he lives right here in the rain-forest of the Northwest. YEA! AND he is having fun building them. As for the tubes - They are all NOS except for the Telefunken, and besides, I have lots to build with and plenty left over for my museum. Um mm... My Master Piece and Wonderful Creation in my Dream Museum! Ahhh... I like the way that sounds. Makes my day brighter. Thanks for writing, Bob Carver

Q: Beautiful MIND & Excellent Design > Simply Beauty... BRAVO !!! Aug-18-08

A: Hi 'cat, Wow. What a beautiful thing to say and what an original way to say it! Thank you 'cat from the bottom of my heart. Now I'm spooky, because if you look closely I'm levitating as I walk; my feet are not in touch with the ground. Thanks for writing in, Bob Carver

Q: mr bob You are known all over the world you are the greatest PLEASE MAKE MORE STUFF AND SIGN IT. ALSO TIM IS A NICE PARTNER FOR YOU BY THE WAY MY WIFE THINKS YOU ARE HANDSOME, IT MUST FEEL GOOD TO BE ABLE TO MAKE GREAT STEREO EQUIP AND BE HANDSOME ALSO. GOD BLESS BRUCE AND CARLA COALE FOREVERMUSIC414 .HOW DO YOU HAVE TIME TO WORK WITH ALL THESE EMAILS YOU GET,, YOU BROKE THE RECORD ON EBAY. IT IS NOT EVERYDAY AN AVERAGE PERSON CAN TALK TO THE BOSS STAY WELL,, I READ ALL YOUR EMAILS YOU HAVE A DEVOTED FOLLOWING FEW STEREO SHOPS WILL EVEN RETURN A CALL. PS I ENJOY MUSIC AND QUALITY EQUIPMENT. YOURS REALLY HOLDS IT VALUE,,,,,,, Aug-16-08

A: Hi '414, I feel lucky to have met Tim - he's a true genius and has been a great partner, even though he lives far away from me. Hey, if anyone says I'm handsome they can be my friend forever. Hi Carla, thanks! Keep on loving music you two. I manage to answer all my mail so far, but I do want to say thanks for writing in advance even if for some reason in the future I can't. Warmest rgards, Bob Carver

Q: Bob This may not be an appropriate place to ask this question but I've noticed in your recent sales that you are very cordial and enthusiastic about answering audio questions so I thought I'd give it a shot. Why did you chose the Yugo 6dj8s for the 490t and C-19 Carver gear? I have both models (and several of your amps) and enjoy them very much. Reason I'm asking is that I recently bought a 2nd SD/A-490t that had Amperex tubes installed. I tend to think the Yugos sound slightly better but can't find them too easily these days. I'm sure your ears are more critically tuned to tube listening than mine. Just wanted to know your thoughts and if there is a specific tube brand I should look for if I can't find a couple of Yugo 6dj8s for my 490t? I wont't be able to attend Carverfest or I would just wait and ask you in person. Good luck with your sale(s), they are impressive. Thanks Mark Aug-16-08

A: Hi Mark, Not to worry, I have a nice stash of vintage Yugo 6DJ8's in my museum. A few more than I need actually. I'll send you a pair free if you send me a reminder next week. Thank you, Bob Carver

Q: Mr Bob Carver , you old Mammiejammer , how are ya dude?? One of a kind , kick ass tube amp , partially designed by an Audio Icon.........Very Very Cool !!! Unfortunately , if I was to bid & win this exquisite work of art I'm afraid it would take up permanent residence in my ass , thanks to my very understanding wife : ) I know , its not a question. I really just wanted to say. Thanks for your proficient accomplishments in the audio field : ) Peace Brother Tom Aug-16-08

A: Hey Tom, You are making my day! Thanks for the thanks! I mean it. As for your permanent residence, think priorities, priorities, buy some flowers, make a bid, take a chance and let 'er rip. Bob Carver

Q: Hello, May I impose on you for a suggestion on what preamp would be a great match with your amp? I listen to vinyl and CD's. Best regards, Durs Aug-16-08

A: I would get a Citation I designed by Stu Hegeman or an EAR 864 designed by Tim de Pravicini. Both have magical phono stages: pure magic and the Citation has tone controls. The EAR is a great choice, with the worlds quietest phono stage, but no tone controls. Nice query, Bob Carver

Q: HI , SINCE THE BIDDING IS GOING TO GO WAY PAST MY CURRENT RESOURCES I'D LIKE TO ASK YOU TO CLARIFY SOMETHING FOR ME, I'M DISABLED FROM A 12,000 VOLT ELECTROCUTION AND RESULTING BRUSH FIRE SO MUSIC IS NOW MY PASSION MORE THAN EVER, I HAVE 2 NEWER MAC MC-275'S AND I'D LIKE TO KNOW WHAT IMPROVEMENTS I COULD MAKE TO THEM IF ANY, AND WHAT TUBES TO USE, I HEAR SO MUCH ABOUT WHAT DIFFERENT BRANDS ARE LIKE BUT IT'S SUCH A MYSTERY TO ME, ANY HELP IS VERY MUCH APPRECIATED, THANKS, ROB MCRAE IN COLORADO SPRINGS Aug-16-08

A: Hi Rob, 12,000 volts! Holy moley! I hope you are able to enjoy music as much as ever. As far as the 275's go, I would add lots of energy storage to the power supply. If you contact me after the auction, I'll send you some capacitors that will do the trick. Output tubes - brand new Shuguang output tubes are really great these days. Front -end tubes best to get used vintage RCA, GE, Tung-Sol, Sylvania, Raytheon or even NOS. Except they can be expensive. Thanks for writing, Bob Carver

Q: Hi Bob! Great pair of amps. Marantz fan here with a 7, 8B and 10B. Hey, I was wondering if you know the whereabouts of A.P. Van Meter with whom you used to work back in the Phase Linear days. Best regards, crooner Aug-16-08

A: Hi Crooner 7c, I don't have a seven or 8B, but I do have a 10B. I have lost touch with A.P.Van Meter over the years, but I'm pretty sure he is retired and still in the Seattle area. Try the phone book - if no A.P. contact me after the auction. Thanks for writing, Bob Carver

Q: Hi Bob, Very surprised to see you here on ebay. Do you think you could start making kits for those of us that remember Heathkit and Dynaco? The only time I get to solder is to repair something. I'm sure there are many in the hobby that feel as I do. Thanks, Alan A Aug-16-08

A: Hi Alan. Man, I would really love to make some kits, especially vintage vacuum tube ones. It's a great idea and would be good for me and fun for you. Sadly though, these amps are built out of parts from my museum, and if I used them for kits, they would be gone too soon. Maybe someday.... great idea! Bob Carver

Q: Hi, When are you guys going to turn your talents toward helping out us amateur and CB radio operators who need a great, multiband vintage-style RF linear amplifier with a filtered design that keeps our RF out of the neighbor's baby monitor, TV, and phone? Your workmanship is so neat and elegant, wow! Great job guys...everyone is so blown away by your amplifiers. Aug-15-08

A: Uhhh..... Also, thanks for the accolade, now we're truly blushing! Bob Carver

Q: Hi Bob, Can you tell me why there are (3) Red terminals on the back of each Amp & only (1) Black? Thanks, Lasareath Aug-15-08

A: Hi Lasareath, The black is common to the four red terminals; the color black is a standard to signify this. The four red terminals are different output transformer taps to allow different speaker impedances to be used. Taken Together, they range from one ohm to 32 ohms. Thanks for asking, Bob Carver

Q: Mr. Carver, My wife said if I bid on these amps I will be eating bologna for the rest of my life. Do you have any good recipes? Excellent amps, good to have you back on e-Bay! John Aug-14-08

A: Hi John, Priorities, priorities! Thanks you. Bob Carver

Q: Hey Bill, Is that a tuna fish sandwich? I really love the Vintage Iron hand made/signed concept. I sold amps like this 10-years ago, called them Vintage Iron or VI - made out of excellent Fisher (Todd NY) iron. Think I figured out your audio output diode rectified DC bias voltage feedback circuit to cook the tubes hotter with music playing, cooler when idling - need to try in my own VI amp and see how this works (oscillation?). Great idea offering genuine high caliber hand crafted amplifiers that are works of art, lifetime keepers that are signed by the masters. Rewarding for all involved. Sell on eBay in 30 years for $100k? Aug-13-08

A: Hi Paul, Cheese and bologna. Sounds like you had a lot of fun building amps too. And thanks for saying they are works of art! If you wish, I'll e-mail you a copy of the DC restorer circuit at the close of the auction. Please send me a reminder though. Bob Carver

Q: Hi Bob, 'was doing some late night eBay browsing when I ran across your auction. I'm 44 and started into audio at age 13 with Pink Floyd and a Dynakit. Anyway, I have some vintage B&K test equipment that you may be just the guy to help me move it. Please check out this eBay auction 250276768607 Thanks. Aug-13-08

A: Hi 'Ral, Will do. Bob Carver. Ha! I started at age 12.

Q: Hi Bob, I don't know if you're religous, but if you are, Jesus told me I was supposed to have these amps. thanks,(and God Bless) fred Aug-13-08

A: Hi Fred, I hope I can help - I'm saying my prayers for you right now. Jesus and I are with you. Good luck and may light shine on your bid. (With a little help from you of course.) Thanks for writing in, Bob Carver

Q: Hi Bob, pleasure to talk to you again. Last month you sold a pair of mono tube amp, using GE 6550 output tube and uses 12bh7 driver, same have 6AL5/5726 DC restorer. Identical on power bandwidth frequecy response of 2hz to 95khz with power output of 180watts each. The questions: Is the one you have now that uses KT88 design by you & Tim is this the same topologies/circuitry of what you have now, I thought you mentioned 6550 tube is the best according to Stu Hegeman. Question#2: My speaker is electrostatic, is this amp takes lower loads down to 2-1.5 ohms. Thanks, hope you make more amps like this & long live to you. Nappy Nagayo Aug-13-08

A: Hi Nappy, This amp is the same as the first one that was designed by Tim and me. Still, Stu Hegeman did indeed like 6550's better than KT88's, and that's why I used them when I built his phase inverter/driver circuit. This amp can use the 6550 or the KT88. It can easily drive an electrostatic even at 1.5 ohms; the output transformer is configured for one ohm and up.

TomDac · Aug 22, 2008

Q: Hi Guys! Can the Neg Terminals be strapped together?, I have a pair of Polk Audio SRS 2's and they need Common Ground amps Thanks, Lasareath P.S. Bob, If you get the chance, check out my Polk Audio SRS 1.2TL's powered by two TFM-35X's on YouTube by searching for "Lasareath Bjork" Aug-13-08

A: Hi Lasareath, Yes. All you have to do is put the amps close together side-by-side, then connect the two negative terminals to each other with a short common wire. Viola! Bob Carver

Q: Two questions: #1 Will these be the only two made? #2. Do they have asymetrical holographic charge coupled magnetic activated sonic detectors? Aug-12-08

A: Hi Paul, Answer, question #1 - See an earlier question and answer regarding all my vintage amplifier parts. Answer, question #2 - Bob's my name, amps are my game, and if I invent it, I get to choose it's name. Thanks for the playful question, you made me laugh. Bob Carver

Q: I'll never forget the Stereophile review where you Bob Carver would take your solid state amp and modify it to sound exactly like a tube amp. I doubt it did. A friend of mine bought a 1.5T amp and at low volume it sounded fair which I assume was that Wima cap in the feedback loop but at higher volume it seemed to roll off the highs and lows and basically screamed a harsh sounding midrange. We modified the heck out of it but never got it sounding great. I'm sure this tube amp you have here sounds good. My present favorite amp is my old Audio Research D90 connected to my Acoustat electrostatics. Even though I didn't like your products I have alot of respect for you and what you tried to do. Aug-12-08

A: Hi 'dios, I came pretty close though - with a difference of three parts out of ten thousand. Read all about it! http://www.carveraudio.com/CarverChallenge. And besides, you are right about these tube amps - they are way better than the tube amps Stereophile used in The Challenge. Not to be compared. And besides, it was so long ago. Thanks 'dios - thought provoking comments, Bob Carver

Q: If i rob a bank and the notes are non sequential will you take cash,just kidding.I dont know what the hell half the parts do,but by God if thats not a work of art i dont know what is,BEAUTIFUL ,its nice to dream.Now compare that to class d,sorry couldnt resist. Aug-12-08

A: Hi Alleib, In this case I would say BEAUTIFUL is definitely in the eye of the beholder - it's good we all love amplifiers, but hey, I'll take it that way! Thanks for the kudo. As for class D, perhaps someday, just not yet. Bob Carver

Q: 100% W0W! Going through 12 pages of vintage amps, your amp is truly amazing! I will be placing a bid.... Regards. Central Park Ron NYC. Aug-12-08

A: Hi Ron, 12 pages of vintage amps? What 12 pages? Can you tell me? I would love to read more about vintage amps. Thanks for the confidence! Means a lot. Bob Carver

Q: Please advise the shipping cost to 38732. Will the item be packed in strong cartons? Thank you. Aug-12-08

A: Shipping will be approximately $117 dollars. We will double box each amplifier separately, as well as the vacuum tubes. Each unit will be wrapped in a special protective wrap, then put inside a plastic bag. Subsequently, bubble wrap and foam corner blocks will be used to hold it in place inside the first box. After that, an additional set of corner blocks for the outer, second box will be used. Safe and sound! Good question, Bob Carver

Q: Hay Bob and Tim Are these two going to be the only ones you do? Or do you have enough parts for more sets? or for that matter another design? Thanks RC Aug-11-08

A: Hi RC, I'm sitting here cross-legged in the midst of all my vintage parts. I have tubes, power transformers, output transformers, old time sockets, line cords, even vintage transformer covers all around me. Many parts, so little time. I really don't know when I'll build some more, but I just know I will. I couldn't stop building amplifiers even if I wanted to. As my museum gets smaller and smaller.

Q: NICE HAT BOB! Aug-11-08
A: Thanks Man. Nice bid!

Q: Aloha Gents, Is there any provision for upgrading the power supply cable for these beauties? Mahalo, Tiki Toenee Aug-11-08

A: Hi Tiki Toenee, Since IEC sockets were not yet invented during the vintage tube era, and this amp is built from my stash of vintage parts, it comes with a fully upgraded and dedicated supply cable. Bob Carver

Q: Sir, Just a note to say what an honor it is just to view the pics of such a wonderful looking and Im sure outstanding set of amps. More like works of art. Sure wish I had a blank check. Dan in Vegas Aug-11-08

A: Hi Dan, Thanks for taking the time to write, and for the encouraging comments. You are making my day. Bob Carver

Q: I am watching these awesome amps, I have to ask if this auction will run its full time? Thank you Aug-10-08

A: Hi '104, Yes, that's our intent and it certainly yields the most interesting and fun auction. mmmm "awesome". I like that. Thanks, Bob Carver

Q: Hi I like it! Please let me know the shipping fee to Los Angeles , CA 90061.Thanks Ho Aug-10-08

A: Hi '268, Glad you like it! Shipping is approximately $95 dollars.

Q: How does the sound of these amps compare to the Luxman 3045 or MC 40's? I think the Luxman sound is clear and pretty distinct while maintaining a good low end. I think the Mac sound is a bit muddier in the low end. I prefer the Luxman sound. I have a Luxman preamp to get the system started. Please do your best to answer this very subjective question. Roland 541-868-6512 cell Aug-09-08

A: Hi '8n8, The Luxman 3045 is superb but very rare, and it does sound absolutely exquisite! I love the delicacy of the 3045 over the MC-40. Always have, and of course these mono-block amplifiers carry a very similar lineage. Thanks for asking, Bob Carver

Bernard · Aug 22, 2008

Thanks for posting that, Tom. It would have been a shame to lose that info.

MotorToad · Aug 22, 2008

Wow, bidding ended at $5800. That strikes me as a bargain for that sort of tube power.

User211 · Aug 22, 2008

MotorToad said:
Wow, bidding ended at $5800. That strikes me as a bargain for that sort of tube power.

I would say whoever won them has got a real bargain. It is a risk, though, without a listen. I don't think I have ever seen an ebay auction with so many questions, and such comprehensive answers. Great post - really enjoyed reading it - and Bob is so friendly! OK I guess he was doing the sell, but what a good sell.

I think he would have felt disappointed that they didn't go for more....

Unison212E · Mar 4, 2011

"
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.
"

Sorry Bob,

My Audio Cyclopedia dated 1959 , on page 547, has shown that the Altec Lansing 436B compressor amplifier also used the same "a DC restorer" circuit that you have claimed invented, what a coincidence, used the same 6AL5 tube. Care to clear-out the smoke? Attached is the schematic.

User211 · Mar 4, 2011

As an engineer, I often think those perceived as the best engineers are, in fact, simply the best plagarists with talented verbal attributes.

So Bob possibly lifted the circuit... we can forgive hm for it, I'm sure.

TNRabbit · Sep 11, 2011

Unison212E said:
"
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.
"

Sorry Bob,

My Audio Cyclopedia dated 1959 , on page 547, has shown that the Altec Lansing 436B compressor amplifier also used the same "a DC restorer" circuit that you have claimed invented, what a coincidence, used the same 6AL5 tube. Care to clear-out the smoke? Attached is the schematic.

From CarverFest this morning:

Over coffee this morning, I had a chance to sit down with Bob and show him this thread, Gary. Here is his response, right from the horse's mouth.

Bob Carver wrote: Thank you for your question as it's a good one. It's not a DC restorer circuit, it's a compressor circuit. It's the difference between a Ninja motorcycle and a walking stick. They are completely different.

If we inspect the circuit carefully, we note that the Altec circuit is AC coupled and is configured as a simple compressor circuit over a threshold. Compressor circuits have been with us since the beginning of time and are designed to prevent overload. It's a simple compressor [Well designed and fully balanced] and that's what it is. Most professional audio gear has a compressor somewhere in the signal chain and this Altec is no exception. It has in common with my circuit a 6AL5 vacuum tube, a simple vacuum tube diode. 6AL5s were used by the zillions in every electronic circuit ever built that needed a fast, small signal rectifier including FM tuners, radar transmitter, television receivers and on and on.

I was inspired by an old DC restorer in the video amplifier section of a vintage TV set. A video signal must retain it's DC value. Hope this helps.

~Bob Carver

And FYI; Bob is indeed a NICE GUY & willing to spend time just talking audio/electronics with anyone. He's deep in the foothills of the Smokie Mountains in North Carolina this & next week for CarverFest, where a group of Carver enthusiasts gather every year for about 7-10 days to enjoy good music, good food & drink, & good conversation with Bob & other audio enthusiasts. Some pics from the first couple of days, including the prototypes of Bob's new ALS (Amazing Line Source) speakers:

"NOS" Vintage amp by Bob Carver/Tim Paravicini

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