Something tells me that bob carver doesn't pop up in the tube forum all that much... however, I found a schematic for an all-tube design with his name on it. It looks appropriately complicated and, well, Carver-ish. I am rather intrigued and was wondering if anyone knew anything about it, as my googling has failed to turn anything up. There should be a schematic at schematicheaven.com in the post 70's section.
There was a car made by Lotus called the "Seven". A friend of mine has one. After Lotus ended production another company made kit cars called "Super Seven".
Bob Carver left Phase Linear to start Carver Audio. His first product was the M-400 "Magnetic Field Amplifier". I still have mine, and I have a schematic somewhere. There is nothing "magnetic" about it. It is a class G amplifier with 3 different supply rails and 3 sets of output transistors per channel. It uses a crude SMPS with a 60 HZ switching frequency. Most experienced exploded triacs.
Bob was famous for talking up his amps, and talking down the tube amps of the day. He did some demonstrations where he claimed that one of his big SS power amps could be made to sound just like a tube amp with the addition of a magic device between the amp and the speaker (a big resistor).
A small but fanatical piece of the high end audio market wasn't buying into it, so Mr. Carver decided to make the mother of all tube amps. The SILVER SEVEN was born. Googleing will find some info. Apparently there were several different versions of the Silver Seven.
I have never seen one myself since they were way out of my price range. I had a friend who was a Carver dealer and he refused to go near tube equipment. He did however talk me into buying the M-400. His story was that the early Silver Sevens had heat related failure issues. Well He sold 12 of the M-400's. They did not have a power switch, and the manual strongly urged that the power cord be plugged directly into a dedicated outlet. I ignored that advice and plugged it into the switched outlet on a Phase Linear 4000 preamp (another Carver creation). My M-400 is the only one of the 12 that is still working. The others all had their triacs exploded by lightning.
So is/was the M-400 worth it? That was the tiny 200 watt Cube amp, correct? I remember a friend having one and it was atrocious. Thin, no soundstage and lifeless...I remember a Electrical Engineering friend saying it was a glorified automobile amp.
I credit my Carver TFM-15 amp and matching CT-6 Preamp for getting me OUT of audio for 10 years. I had a bug up my you know what to replace my beloved Luxman receiver with this Carver amp/preamp jobbie after graduating college. Spent my first month's salary on it too...I totally hated that system and wished I never got rid of that Luxman. My B&W DM220i sounded awful. I long considered Carver to be the Bose of Amplifiers.
A friend of mine absolutely loves his Sunfire amps...don't know anything about the new Carver stuff....but I am looking forward to having my friend over to check out my Krell KSA Clone soon.
I credit my Carver TFM-15 amp and matching CT-6 Preamp for getting me OUT of audio for 10 years. I had a bug up my you know what to replace my beloved Luxman receiver with this Carver amp/preamp jobbie after graduating college. Spent my first month's salary on it too...I totally hated that system and wished I never got rid of that Luxman. My B&W DM220i sounded awful. I long considered Carver to be the Bose of Amplifiers.
A friend of mine absolutely loves his Sunfire amps...don't know anything about the new Carver stuff....but I am looking forward to having my friend over to check out my Krell KSA Clone soon.
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Ahhh... the amp is listed under "Super Seven" on a website. But my god... the OT in that amp is comical.
I have an M-400 in my dorm room, currently being a paperweight/doorstop. When it works, its decent with good speakers. The filter caps decided to call it a day and completely burned through the board... alas... "forcing" me to get 5 Marantz monoblocks.
I have an M-400 in my dorm room, currently being a paperweight/doorstop. When it works, its decent with good speakers. The filter caps decided to call it a day and completely burned through the board... alas... "forcing" me to get 5 Marantz monoblocks.
hey-Hey!!!,
Resurrecting a Carver PM900 was the start of my re-entry into Hi-Fi. It suffered a driver transistor failure that cascaded into the power supply(s). Rebuilt the board, replaced the caps and then had to find that failed transistor...🙂 I wound up trading the thing for a sack( truckload actually) of tube gear that included a consec. numbered pair of MC75's. The repaired PM900 is still in service a decade later...holy smoak, it has been a while now! IMO, Bob's stuff has never followed any simple design. In any case, it isn't anything more than a SS amp, and I'm not building any of those now; tubes just work better for my ears.
cheers,
Douglas
Resurrecting a Carver PM900 was the start of my re-entry into Hi-Fi. It suffered a driver transistor failure that cascaded into the power supply(s). Rebuilt the board, replaced the caps and then had to find that failed transistor...🙂 I wound up trading the thing for a sack( truckload actually) of tube gear that included a consec. numbered pair of MC75's. The repaired PM900 is still in service a decade later...holy smoak, it has been a while now! IMO, Bob's stuff has never followed any simple design. In any case, it isn't anything more than a SS amp, and I'm not building any of those now; tubes just work better for my ears.
cheers,
Douglas
I've had a TFM-55 for a couple of years now, totally recapped it and modified it with some Allen B resistors, better trim pots, transistors etc.
I love it. Drives my Klipsh speakers brilliantly with so much headroom.
BTW I'm driving the TFM-55 with my DIY tube preamps. It brought the Carver design to life.
But one of these days I will build tube monblocks. Just a matter of transformers. Can't buy them here🙁
Last year Bob sent me the schematics of one of his one time signed tube amps sold on ebay recently.
If I remember correctly it was 2 monoblocks with 8 KT88's per channel. standard gain stage with phase inverters and some little so called tricks in his circuitry.
I love it. Drives my Klipsh speakers brilliantly with so much headroom.
BTW I'm driving the TFM-55 with my DIY tube preamps. It brought the Carver design to life.
But one of these days I will build tube monblocks. Just a matter of transformers. Can't buy them here🙁
Last year Bob sent me the schematics of one of his one time signed tube amps sold on ebay recently.
If I remember correctly it was 2 monoblocks with 8 KT88's per channel. standard gain stage with phase inverters and some little so called tricks in his circuitry.
I had a system that I had built out of other peoples leftovers or dead components that I had resurrected. It was made while I worked as a repair tech at an Olson Electronics store. There were two Voxson solid state receivers running in a bi-amped configuration using the receivers tone controls as crossovers. Low frequency speakers were University Labs 12 inch dual cone (12TRXB?) in home made cabinets. The mid / highs used 6X9 inch car speakers with piezo tweeters again in home made cabinets. The turntable was a Garrard Zero-100 (remember those). I had that system for about ten years and loved it. It had a realistic sound stage and a close your eyes and you are there sound.
I got a job at the Motorola plant (where I still work) in 1973. There was a group of "audiophiles" working there who had systems costing big money. Most of them laughed at my junk but a few who took the time to actually listen, wondered how I got it to sound so good.
I still had my "junk system" in the early 80's. All of the tube stuff that I was building was MI equipment, since I actually liked my stereo stuff. One of the audio gurus had made a deal with the Carver distributor. If he could pre - sell 10 of those new fangled M-400 cubes, he could become a Carver dealer. I agreed to buy one of the cubes and his old Phase Linear preamp for less than the local high end store wanted for the cube alone.
I got the "high end stuff", hooked it up and wasn't too impressed. It just didn't sound realistic, and there was this annoying ticking sound. It was loud, really loud, but to me that was its only attribute. Yes, Carvers little cube claimed 200 watts per channel. The manual warned sternly that attempting to actually measure the output power would blow up the amp and void the warantee, so I never did. They also warned against using it for a guitar amp, which I did do, and it worked good. Regardless of the actual power output it wound up blowing my University Labs speakers. The Phase Linear started getting erratic (worn pots, bad caps) so the whole thing went into the warehouse where it still sits. I used a yard sale Fisher tube receiver for a few years until I built my own system.
The M-400 that I had was one of the very first units. It was a silver (or light gold anodized) box. The later units were black. There was no power switch so the unit stayed on all the time. The power supply used a triac that pulsed on briefly at low output powers. The pulse resulted in an audible tick from the amplifier itself. The large current pulse would make its way to the speakers if the system wasn't carefully set up. The current pulse was large enough to blow the line fuse occasionally. Against advice in the manual I put a slo-blo fuse in mine. Again against advice in the manual I plugged mine into the switched outlet in the preamp since I don't like leaving things powered up when I am not home. The power grid in Florida hits multiple lightning hits a day in the summer. All of the other units thas were bought with mine died as a result of lightning strikes. Carver refused warantee service on these units and wouldn't sell us triacs either. They claimed that a bunch of electrical engineers weren't qualified to service these units. The guy who got the units eventually got the service manual and a bunch of triacs from the distributor. He even managed to secure a "one time upgrade deal" for all of the original purchasers. He got a rack mounted 1.5 killowatt monster, but I decided to "just say no" and stick with the Fisher.
I still have the Carver, the Phase Linear, both Voxson receivers, and the Fisher receiver. The Carver and the Fisher still worked the last time I tried them. I wanted to hook up the Voxsons to see if they really did sound as good as I remember, but neither one worked. I have no desire to hook the Carver back up except maybe as a really loud guitar amp (until it blows up). The Phase Linear preamp did have a dynamic range expander and an "auto correlator" that did a good job of adding some life to dead (over compressed) recordings or FM radio, but it would require a major rebuild.
"Last year Bob sent me the schematics of one of his one time signed tube amps sold on ebay recently. ------ standard gain stage with phase inverters and some little so called tricks in his circuitry. "
Like this?
http://www.diyaudio.com/forums/tubes-valves/135052-what-if-o-h-schade-had-mosfets-2.html#post1689375
Like this?
http://www.diyaudio.com/forums/tubes-valves/135052-what-if-o-h-schade-had-mosfets-2.html#post1689375
Nice to see another Motorolan here. I was there from '76 until 2005 when I ended up on disability. I worked for SPS and GED Computer Services Group in AZ.
Dave
That's the one exactly!!
The DC restorer with 6AL5. He sent me some drawings of this in his latest vintage amp build that was sold on ebay.
You read my mind.😛
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My recollection was this was his "benchmark" to prove the characteristics of amps are all just their frequency transfer function, so he made a Tube and a SS to match to prove it. The tube was well very respected and he had to sell a bunch of them due to demand. The solid state was considered a turkey.
As usual, Bob Carver applied thinking for his designs outside of mainstream audio circles. No surprise his tube topology was not a classic design. He was not big on classic. I laguhed my head off when I saw the schematic for the "magnetic" amp, as I recognized the design concept. I also know the origin of the auto-correlation. An idea out of RF.
As usual, Bob Carver applied thinking for his designs outside of mainstream audio circles. No surprise his tube topology was not a classic design. He was not big on classic. I laguhed my head off when I saw the schematic for the "magnetic" amp, as I recognized the design concept. I also know the origin of the auto-correlation. An idea out of RF.
I had a pair of Silver 7s and still have the replacement KT88s for it.The amp used 660v on the plates and used cheap Chinese tubes in the output and you can guess the result of that.The voltage and driver stage used pentodes,I converted them to quasi-triodes with a simple 100 ohm resistor and must admit it made a very big difference.Stock the amp had a similar sound quality to a stereo 70 with much more power,slightly veiled and whenever I listened to it I thought of carmel candy.At one time I also had a Phase Linear 700B used with one of Bob's Phase Linear 4000 pre amps,the speakers were AR LSTs and I could not tell the difference between Joni Mitchell and Joan Biaz using that system,a true horror to listen to,sold off the Phase stuff and bought a pair of Dyna Mk3s and never regretted it.Cheers.
I was working in a stereo shop in 1974-75 in Boise ID (Great Western Distributing catalog show room) We had, in that time and in that town, a good line up (Dynaco, JBL, Infinity, Marantz Sony Kenwood Pioneer, Bose, Kipsch, Sonab, Philips, I was in the process of getting a new system while there waiting for my "real job" and centered my desire on the Philips Bi-Amped motional feedback "David" speakers and was prepared to pony up the $$ and get the Phase Linear 4000 preamp ( cooling looking 4 channel Preamp with Sonic Holography, Auto correlator etc ) It was a financial stretch from my post college retail job paycheck. Was finally ready to get the 4000 and the store got the new Dynaco PAT-5 (and the Dynaco Stereo 400) that same day. I went in on my day off and spent 2 hours A-B'ing the 2 preamps and the Dynaco PAT-5 kicked the PL 4000's ***. I got mine in kit form on the "salesman in the biz deal" with the Philips motion feedback speakers and Philips 209 turntable, it was a lot of fun
still like the sonic Holographic processor and the auto correllator but the sound of the 4000 -not!
In spite of that, I have a lot of respect for Carver, his many achievements and contributions to the audio industry and community
still like the sonic Holographic processor and the auto correllator but the sound of the 4000 -not!
In spite of that, I have a lot of respect for Carver, his many achievements and contributions to the audio industry and community
A friend asked me to look at his Carver Vacuum Tube Preamp. Imagine my surprise when I opened it up and saw an ocean of OP amps and two lonely 6DJ8s with about 28V on their plates. The PS consisted of a smallish transformer, silicone bridge, cap and three pin reg. And my friend was very proud of this preamp; it was designed by Bob Carver! I hated to pop his cherry. Bobby's quite the self promoter.
At one time I too respected Carver for his knowledge, design ingenuity and innovations. But in my opinion he has fallen from grace. He has taken up buying junkie little amplifiers and rebuilding them...well almost. After a gaudy coat of red paint and a few new PS capacitors he puts them on eBay. This in itself is not a bad thing. What's reprehensible is the amount of unmitigated hype he puts up for the unsuspecting and ill informed buyers. And Bob is the master of this. Here he even shamelessly invokes the name of Stu Hegeman to link to the amplifier and improve it's worth. Take the time to read the hype and you'll see it's all factitious supposition. And once, in an earlier auction that I can't link to, he claimed his special output transformers were made of "adamantine steel" (ala the 1956 movie Forbidden Planet) which doubled the output power. I feel sorry for this once great designer that has to resort to this demeaning rhetoric.
Back in 1986, I bought my first "real" stereo system. It consisted of an M-400 cube that I picked up from a local high end stereo store in their consignment room, a proton integrated amp that I used as a preamp, a denon dp-1200 turntable with an AT cartridge, and rebuilt Advent speakers. I had bought a sub woofer from a custom builder (still in business btw) that had a 10" driver and two 10" passive radiators. That things was HUGE compared to what is out there today. I used the advents as satellites with the sub.
Anyway, not having really heard tube gear other than my moms magnavox console unit, I thought I was sitting in high cotton. I used it for several years and finally ended up trading it all to my brother for babysitting time...lol. Now I am tube only. I do wish that I still had the denon table though......
Anyway, not having really heard tube gear other than my moms magnavox console unit, I thought I was sitting in high cotton. I used it for several years and finally ended up trading it all to my brother for babysitting time...lol. Now I am tube only. I do wish that I still had the denon table though......
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