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Bob Carver is at it again~


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Interesting Q&A from the auction:

Hi Bob... glad to see the latest set of amps here on the BAY! I wish
that I could run a set of these for even a week! Are they able to be
strapped together so they can run a set of speakers that need a common
ground design amplifier? And have you thougt about a stereo tube
design? Mar-12-09

A: Hi 'john1, Hope you like these red ones on
the Bay! Yes they can be strapped, and yes I have thought about a
stereo tube design for about thirty micro-seconds. The problem is they
would be too heavy for me to easily lift if I designed them the way my
inner voice says. Thanks for your enthusiasm... means a lot to me, Bob

Q: dear bob....I know what voltage you have to use on the
output plates.....but what are you using for the screens?? Just curious
cordially neal Mar-12-09

A: Hi Neal, I love questions about
screen voltage because it gives me the opportunity to talk about
screens. What I did regarding the screen voltage was to perform a
series of converging experiments at the time I designed these
amplifiers. The experiments were quite involved, but here are my
conclusions: Ultra-Linear screens reduce the maximum output current too
much for me, and hence the ultimate performance of the amp.
Ultra-Linear screens also saddle the output tubes with dangerously high
voltage essentially equal to the plate voltage, often causing
catastrophic and unexpected arc-over failures. I don't like that. I
concluded, for better or for worse, that Ultra-Linear was scant more
than a money saving method simply because it eliminated a second power
supply. As far as the triode-like output impedance that it yields,
KT-88's with a DC restorer and screens fed from a separate power supply
can easily yield performance superior to the best Ultra-Linear
configuration. Stu, Tim, and my own experiments taught me that. I
operate the screens at exactly one half the plate voltage, or 330 volts
DC. Good question; thanks for asking, Bob Carver

Q: Hi Bob - You
are my hero!!!!, you and Nelson. I had an off the wall inquiry, can Joe
work on old Western Electric gear? I'm a recording engineer and I need
a WE mic pre spec'd out, recapped etc. can you get me his email? Thanks
so much. Mar-12-09

A: Hi '265, I felt like a hero yesterday, but
today I cannot find my red cape and flying goggles, so I'll have to be
a hero without them. You are making my day! Thank you '265. Joe can
literally work on anything, especially old Western Electric gear. I'll
forward this to him, and you are very welcome. Hero...Hmmm...Bob Carver
Do I need a pre-amp to run these? Can you recommend one if so? Do you
have one? do you have recommended speakers for these amps? Can I call
you with more dumb questions? I am new to the tube amp world anf have a
few more questions. Mar-12-09

A: Hi 'comm, Yes you need a
preamp. A vintage Citation I, Carver C-1, or Audio research SP-3.
Others as well. I have lots of preamps. Their ARE no dumb questions
except those that are never asked, so call anytime! Enjoy the tube amp
world...it's lots of fun and very musically rewarding. Hope this helps,
Bob Carver.

Q: WOW, Bob Carver himself. It's great to see you
back into tube equipment. I have a question about these amps, if you
won't mind explaining. Sweet amps! Gorgeous! How do they get more power
out at six ohms since they have output transformers that match loads?
Thanks for your time, Chris Thomas - Texas Mar-11-09

A: Hi.... Hey, I just answered that question! Warmest and best, Bob Carver

WOW, Bob Carver himself. It's great to see you back into tube
equipment. I have a question about these amps, if you won't mind
explaining. Sweet amps! Gorgeous! How do they get more power out at six
ohms since they have output transformers that match loads? Mar-11-09

Hi '33, Here's how: a pair of KT-88's are rated for 100 watts of audio.
Since I'm using three sets for 180 watts, or 60 watts per pair, they
are operating conservately and are substantially underloaded. Now
suppose the amp is delivering 180 watts into eight ohms using the eight
ohm transformer tap, and suddenly the load changes to six or even four
ohms (as can easily occur in a complex speaker load) as the frequency
changes. Now the amp is more heavily loaded, and the power output can
increase to almost three hundred watts ON THE EIGHT OHM TAP! The irony
is that if the speaker were then connected to the four ohm tap, the
power would drop back to 180 watts. This tube amp is really surprising
that way (in that the power goes up as the impedance goes down) as
those six mighty KT-88's continue to deliver ever more current and
hammer on unfazed. They can do that in large part because of the
separate power supply for the screen grids. Great question, thanks for
asking. Bob Carver
More Q&A for the record. I don't understand this stuff but I'm sure it's pure gold to the tube guys:

Question & Answer

Bob back again...so the solution was back to the sliding bias scheme to
shrink the cathode resister as the tubes draw more current.. this time
I use an led driver firing off 3 optocouplers which gradually turned on
a transistor in parallel with the cathode resister.. a few extra
resistore and trim pots and I got the same results lively dynamic sound
,efficient cool operation. This time around I abandond the big output
tubes in favor of the russion military version of the 6bq5...I think
they are fabulous. I just keep paralleling tubes to match what every
Dyna OPT I choose, from the little bitty ones to the MK6 They are
really tough.. I am using near 500 on the plates and 250 to 300 on the
screens.. reading your description of you biasing scheme you MUST be
using a sliding bias if you are idling at 25% normal...What is your
method for shifting bias..just the general concept..your amps are the
first I have ever seen in 20 years of looking over the world that got
it right..... Mar-16-09

A: Wow! I truly admire your thinking and
your tenacity regarding the age old bias problem. Your transistor idea
across the bias resistor is nothing short of inspired. Do you sense
current or do you sense voltage to turn the transistor on? I like your
scheme because the delay that will naturally occur is rendered
irrelevant by the energy contained in the the cathode bypass capacitor,
as it MUST deliver the required current during the time it takes for
the control circuits to respond and turn the transistor on. My DC
restorer is not a sliding bias approach, rather its purpose is to keep
the DC value on the control grid at design center even in the presence
of signals that have a DC component. Thank you '541 for sharing your
thinking with me and with all of us. Was a real treat. Best wishes and
warmest regards, Bob Carver

Q: Bob about the magnetic lag at the
polarity flip...the solution was to use TWO transformers one for push
one for pull each one never leaving one polarity...Did it make a
fifference? yes it did and quite noticable (But not as much as the
dynamic bias...) not very cost effective but worth it if you have the
iron By the way ,when I say I hear an improvement I go thru eons of
time setting up two identical amplifiers with just one change,in one of
them ,making sure the levels are the same and blah blah blah the worst
mistake to make is to THINK you hear a change based on MEMORY...Have to
constantly make 'reality checks' and never assume anything. So at this
point I quit audio and went 'underground' with life's necessities..
Next chapter: I surfased again again 10 years later thinking I was now
in love with cathode bias scheme what with self balancing and 'plug and
play' feature..Didnt' take long to realize that a big resister for idle
wasn't cutting for heavy use.(continued) Mar-16-09

A: Continued next.

Bob..back again. so I could set the idle for 12 t0 15 ma and the max to
whatever level I wanted even Way BEYOND what would be considerd safe or
acceptable. This is where I thought it sounded the most lively and
dynamic. Since the tubes were always trying to revert to the trickle
bias condition (the troughs between the peaks, it was very efficient
operation...one set of tubes should equal a lifetime. the heat didn,t
seem any more than filaments at idle,,,no melting plastic cords here,
and under operating conditions never did the plates glow and just
faitly in the dark under heavy use,,,this is high voltage mind you. so
it was the best of all world..best sound high effeciency ,long life At
this point I had to put audio away having more pressing needs to look
after,,,but not before I looked into the possibility of eliminating the
the magnetic lag in the OPT just at the point where the push becomes
pull and vice versa ,,this is where the magnetic polarity flips
(contined) Mar-16-09

A: Continued next.

Q: Bob..back
again...so I could set the idle for 12 to 15 ma and the max on heavy
peaks normalor safe even WAY BEYOND what would be considered acceptable
or safe. This is where I thought things were really sounding good and
dynamic....its as if the burst of bias current added to the signal
induced flow of electrons...here the really interesting part..even
under extreme conditions the plates never got to glowing,,in the dark
just faint glow.as looong as it was music and apeech.. stedy sine waves
was a different story...the thermal stree was just a fraction of normal
run bias because the tubes were doing everything they could to revert
to the idle trickle condition... this is going on every trough between
peaks on the waveform...I could actually put my hand on a tube at idle,
and although hot I didn't feel I was going to get burned most of the
heat seemed to be filament this is really efficient operation and cool
operation in my book.the best of all worlds ( to be continued) Mar-16-09

A: Continued next.

Bob...ok I'm back....as I mentioned pentode sounded the best and the
strss on the screens was taken care of but with hi voltages 'normal
bias' bias ran the tubes too hot....since I knew that the tubes sounded
just fine with real low bias current when playing really soft (I mean
each half still looked like class A on the scope) but quicly caved in
when pushed. it seem obvious that what was needed was a sliding bias
which would manipulate the bias depending on input...it needed to mimic
the dynamic nature of speech and music... I couldn' find any
information anywhere,,so I was on my own...the solution took the form
of an led driver which sequentially lit up three leds coupled to three
cadmium sulfide cell( I didn't know about optocouplers at the time) the
changing resistance in parallel with one leg of a voltage divider in
the fixed bias supply..I few resisters to trim things out and by gosh
it worked perfectly...I could reduce idle to about 12 to 15 ma. ( to be
continued) Mar-15-09

A: Hi Neal '541, Good to have you back!
Your solution to the high voltage and bias problem is extremely
creative, and provided you listened to it deeply, carefully, and found
it to have just the right dynamics for music, speech and our human
hearing mechanism, a tip of my hat to you Neal! Well done. Well earned.
Bob Carver

Q: Greetings again. I have another quick question for
you about these amplifiers. I am currently running a pair of Carver
Platimun speakers. Would I better off using these amps on my speakers
using the original passive crossovers that are built into them, or
would I be better off finaly bi-amping my speaker, and using these amps
on just the ribbon drivers and using my existing amp for the bass
drivers? Thank you for any advice you can offer. Mar-15-09

A: Hi
'io, Either way will work, but here's what I would do. Separate the
woofers from the ribbons while retaining the passive crossover, drive
the ribbon part of the crossover with these tube amps, and the woofer
part of the crossover with your existing amp (probably a solid state
amplifier). You would then be able to independently adjust the level of
ribbon-to-woofer for the balance you like the best. Or you could bi-amp
them and build an external EQ circuit. The EQ is necessary for the
ribbons in order to voice them properly, and to blend them seamlessly
into the woofers. This headache is avoided if you use the built-in
crossovers (The work has already been done.) with just a small loss in
drive voltage due to the passive nature of the crossover. And these
amps have lots of power and current, so not a problem. Great question,
Bob Carver

Q: I have searched around on the net trying to find
contact info for "Tubular Joe" to no avail. As a very pleased owner of
one of your earlier brown sets I'd like to ask Joe some questions about
their construction. Could you pass on my contact info, please? Mar-15-09
Hi 'rama, I haven't heard from you lately; it's good to hear from you,
and yes I will tell Tubular Joe this afternoon. I'm sure he would love
to answer any questions about the amp he so lovingly built. He is the
best! Hope this helps, Bob Carver

Q: hello Bob....near as I can
tell , you put together an amplifier using the concepts I came up with
about 15 years ago. I wanted to see what would happen with jacked up
plate voltages on the outputs and soon ran into distressibg
observations ....the plates were starting to glow even at idle and the
screens glowing on and off like light bulb filaments under dynamic
conditions...there had to be another way....then I found out thar el34s
are perfectly happy with 800 volts on the anode and 400 on the
screen...its right in the tube manual...I was surprized at how low the
screen voltage could be reduced and the tube stll function
fine.....Pentode mode allows this and I always thought pentode sounded
more lively and musucal than UL or triode...I never could understand
the infatuation with triode mode......both triode and ultralinear have
a severe internal feed back mechanism working wihin the tube...pentode
mode eliminates most of it to my understanding..(to be continued)......

A: Hi '541, Your love of amplifiers shows in your
passion for trying different ideas, and you are absolutely on the right
track! It took me awhile to notice that ALL the tube amps I really
liked for sweetness, detail, envelopment and just full blossom power
output always turned out to possess pentode output stages in their
purest form. Pure classical!

Q: oops i fell asleep during last message hope i didnt bungle it up Mar-15-09

Hi Randy, Yes you did, and I could not make sense of your message. The
beauty of it all is we have all the time in the world, so try again
friend Randy, and I promise to get out my Captain Marvel decoder ring
and properly respond. Bob

Q: Bob, One more question if you don't mind.... These are transformer coupled right ? What about OTL designs ? Mar-15-09

Hi'52, I love questions, the more the better! Yes, these are
transformer coupled. OTL designs are great too, but Bob's my name and
powerful amps are my game. OTL designs just don't have much current
output capability, and therefore cannot easily drive difficult reactive
speakers to satisfying levels. But that's just me, still, they can
easily drive vintage horn speakers (and some others too) when we want
to reproduce the sound of wind-chimes at realistic play-back levels.
Feel free to ask more question, please don't be shy. Anybody! Bob

Q: if you had your preferance would you run these with a
set of brysyon 7b or the beautiful jewwls you hold. as the magnapan
tympani 1 B are quite power hungry and i believe 10 watts at 96 db's
could be off here a bit but it isn't much would these develop the lows
needed to warm things up. i also realize that magnapan developed the
tympani 3a's four panels of woofer material to off set the lack of lows
in the ones i have. i would love your advice here. of course i have
bi-amping questions i would hate to bore you with but i can run thre
top end with either two bridged a-760's or two pm900s or run them
ftraight with these or the brystons. i love ur stuff and genuis. randy
hart Mar-14-09

A: Hi 'hart420, I'd hook these amps straight into
the Maggies...the lows would warm up a lot because their impedance
rises nicely on the low-end. The extra coherence and warmth you would
get by running the amps full range into the Maggies would more than
offset the extra volume level you could get by bi-amping. Bi-wiring
(some units had bi-wiring capability, some did not) or straight in is
my recommendation! Glad you love my stuff... hearing that helps make my
day. Thanks for writing, Bob Carver.

Q: Hello Bob, Nice amps. I
have recently read that to control a speaker you need lots of amps
(current). Like 100 A. What do these provide ? What is your opinion ?
Thanks Mar-14-09

A: Hi '52, Controlling a loudspeaker is a
complex, deep and non-trivial issue. Still, and just the same, the
notion that 100 amps is needed is a false belief. The damping current
required for total speaker control is never more than the peak input
current at any given instant in time....micro-second to micro-second.
That's why both two watt and 200 watt amplifiers work, and work very
well. The maximum output current these amps provide is three times the
maximum plate current of each KT88 (Three pair) times the turns ratio
of the output transformer = approximately 26 amps p/p. Thanks for
writing and for the illuminating question, Bob Carver

Q: Hello
Mr Carver, Thanks for the straight on shot (picture), You didn't forgst
did you? It will certainly be of help to me. I will ever be greatful to
you Bob. Best Regards, "jay" Mar-14-09

A: Hi Jay, I'm pretty
sure I sent you a "straight shot". The chassis shot in this auction is
the only one I have, and close inspection should reveal all. I now have
an assistant to help me keep track of my promises, and if I promise to
send you something she will make sure I don't forget. I hope I didn't
already forget; if I have, let me know. Bob Carver

Q: WOW, just
like I want to build! I still own my Phase 400 from 1974 with warrantee
cards. Anyway, Bogen used voltage regulation for the screens on the
KO100 (2 EL34) and the DO-70 (2 EL34s). The DO70 uses the grid voltage
sent to a 12B4A regulator tube to derive the screen current and the
KO100 uses a winding designed into the power Transformer to an EZ81
rectifier tube to derive screen voltage. It seems that the design using
the grid voltage (regulated via 12B4A) to supply the screen voltage is
more stable. Since you have vintage iron, my question is: does your
power transformer have a winding dedicated to the voltage regulator (DC
restorer) OR did you just use the grid voltages regulated down to
supply the screens (easier to do). The design I am looking at also uses
a 6C4 also, which monitors the EL34 current. Did you accomplish the
same job with a 6AL5 or am I off track. Thank You, Mar-14-09

Hi 'frank, I don't know who designed the Bogen amps, but I wish I did.
He or she got it right: separate power supplies for the screen
grids(often regulated), a very modern hi-tech output tube, British
style stability compensation for the output transformer, nice high
plate voltage,I could go on and on. These amps of mine have a separate
power supply for the screens, which operate at approximately 330 volts.
The 6AL5 has nothing to do with the screen voltage, rather it's purpose
is to maintain the correct DC signal component on the control grids
through the entire audio signal swing, allowing each tube to idle at
about 11 watts instead of 32 watts, for any given distortion level and
at the same time eliminating DC shifts and bounces. Hope this helps,
thanks for writing, Bob Carver
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Here's the latest Q&A from Bob's sixth set of tube monoblocks
with meters; VERY interesting reading! 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.
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
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
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
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
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
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
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.
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.
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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Bob Carver sold me as soon as he started making the "T" mods. His silver 7 and silver 9 were great. His last great "Carver" ss amp was that lightstar before he moved on to Sunfire. I dig the amazings as well. I have no qualms with his tube or latest sunfire designs, they work as adveratised.

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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.
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
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
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
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)
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
sound GREAT... ever so sweet " Maravilloso" , Im so Happy , great
packing to¡¡ they arrived in perfect shape.. sending pics check your
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.
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
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
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
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
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
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
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
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
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
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.
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
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"
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
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
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
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
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
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