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Old 16th October 2008, 02:21 PM   #21
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Maybe I should rephrase my original post.

I am looking to build a pair of monoblocs to drive a pair of Klipsch RB-81s They have a sensitivity of 97db. Ilisten to Rock! Im a die hard rocker. At 52 I even listen to some metal. When the wife isnt home I turn it up.

Right now I have a Superphon Revelation Basic preamp driving two Carver M400 200w power amps. I will be swapping out the SS preamp for a modified Marantz 7 tube preamp that uses two 12ax7s and a single 12au7.

I am interested in building something using off the shelf components. Fro a tried and proven schematic and parts list. I am a newbie to the tube world but was originally trained in electronics in the Air Force where I worked on Doppler systems. I know my way around high voltage as the power supply in a B52 doppler radar system had 15Kv for B+

I have many years building and troubleshooting SS and this would be my second tube project after the preamp.

I have looked at a whole bunch of schematics but most of them do not list the model or part numbers for the transformers.

I dont want to have to order a custom transformers and dont need to be loking for a 1960s model one either.

A nice 8 - 10 watt SE or a 20 - 30 watt P/P would work just fine.
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Old 16th October 2008, 07:44 PM   #22
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I was looking at this amp but the iron is way expensive. Just for one monobloc it costs over 800.00 for the chokes and trannys

http://www.magnequest.com/diy_lessard_parts_2a3pp.htm
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Old 16th October 2008, 11:57 PM   #23
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NO WONDER!! Perusing you favorite. the 2A3 push-Pull, It has the most expensive guts...from Iron on down to caps & resistors.
You can look up the specifications of the iron,
et.al. & find way less $ replacements. Those prices are really way out in fantasyland.
_________________________________________Rick..... .......
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Old 17th October 2008, 12:02 AM   #24
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Quote:
Originally posted by billbeau
Maybe I should rephrase my original post.

I am looking to build a pair of monoblocs to drive a pair of Klipsch RB-81s They have a sensitivity of 97db. Ilisten to Rock! Im a die hard rocker. At 52 I even listen to some metal. When the wife isnt home I turn it up.

Right now I have a Superphon Revelation Basic preamp driving two Carver M400 200w power amps. I will be swapping out the SS preamp for a modified Marantz 7 tube preamp that uses two 12ax7s and a single 12au7.

I am interested in building something using off the shelf components. Fro a tried and proven schematic and parts list. I am a newbie to the tube world but was originally trained in electronics in the Air Force where I worked on Doppler systems. I know my way around high voltage as the power supply in a B52 doppler radar system had 15Kv for B+

I have many years building and troubleshooting SS and this would be my second tube project after the preamp.

I have looked at a whole bunch of schematics but most of them do not list the model or part numbers for the transformers.

I dont want to have to order a custom transformers and dont need to be loking for a 1960s model one either.

A nice 8 - 10 watt SE or a 20 - 30 watt P/P would work just fine.

Build with PP KT88s and install UL/triode mode switches. Use DynaClone A431S "iron" from Triode Electronics. Set up with a "shallow" Class "A" operating point. You'll have ALL the power "headbanger" stuff requires and you'll also get the finesse requisite for a "fat lady" or a violin. A good amp plays well, no matter what style of music it's fed.

Use Mullard style topology, with a 6AB4 as the voltage amplifier and an ECC99 as the LTP. Both of the small signal types suggested exhibit a high gm, which provides resistance against slew limiting.
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Old 17th October 2008, 02:31 AM   #25
JoshK is offline JoshK  Canada
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I was going to say that the 60w Acrosound that aardvarkash linked to (first one) would be a good example of good design. Williamson is a classic. I haven't heard one that I know of, but still it is revered. But just follow Eli's advice. He knows what he is talking about.

P.S. I am 1/2 Norwegian by ancestry. Can't speak a word of it. Does 'ufda' count? But we still eat Ludafisk and Lefsa.
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Old 17th October 2008, 05:16 AM   #26
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I would say the advice to build with KT88's in p/p with a Mullard-type front end and a UL / Triode switch would be sound. To be honest you could just wire it in triode and get all the power you will ever want with those speakers. In triode you should get in the neighbor hood of 25watts to 30watts give or take. I would say you could opt for KT77's (EL34's) or KT66's and get about 15watts roughly, that still would be an acceptable amount of power with those speakers.

Think of something like a Quad II modified remake but with a D3a or something of the sort at the front end, some Gold Lion KT66 reissues at the back for that classic look. Or maybe, sticking with the Mullard type front end, something like a modified ground up build of a Marantz Model 5 to pair with that Model 7. I would drop the 6BH6 in favor of something like the 6AB4, 6AN4, 6CW4, etc... or maybe something like the D3a to stay pentode. Followed by a 5687 or ECC99, could maybe look at the 6BQ7 or others. You could also build it as is to have a pair of faithful reproductions, still would be great little amps.

For SE a KT88 in UL will give about 10watt or so. A 300B would drive em' but then you are looking at a much higher cost. You are getting into the range of PSE or large transmitter SE, both of these add cost and complexity. As far as cost though, besides iron, a 813 SE with a 12HG7 front end could be done somewhat cheaply. As a triode the 813 can make about 20watts, more if the transformer can handle a 813 in UL. If you are sticking triode wired you could use the Hammond 1628SEA running the tube at 100mA or less, 120mA is the max for that transformer. If you are worried or wanted to go higher you could get the Hammond 1642SE, but that thing is a F***n' monster. At 100mA Mr. Millett was hitting about 20watts with about 5% distortion. BTW he uses the 12HG7 as the driver great little cheap tube. Unfortunately the PSU is where you will tie up the most money. If you wanted to go higher with the 813 though contact Jack at Electra-Print, one of the greatest guys and will wind you about anything, within reason. Though a custom output for the 813 from him would set you back somewhere between $250 to $500+ depending on what you want as far as taps, power handling, and winding material (partial silver).

Cheers

James
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Old 17th October 2008, 07:44 AM   #27
AuroraB is online now AuroraB  Norway
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Location: Norway, -north of the moral circle..
Just to demonstrate my lack of tube theory..
What's a "Mullard Front end" look like ??...

My link to Pete Millets designs shows just one with switchable triode/pentode mode...
A previous comment said that was of little or no use....?

-----------------------------------------------------------

BTW - Lefse is OK..."Ludafisk" - or lutefisk in standard norwegian- is for the initiated and breave at heart

"Uffda" is still OK- something you typically say when the toddler stumbles in his own feet, or something mildly bad happens...
sort of like " Oops" - or slightly worse........
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Old 17th October 2008, 10:55 AM   #28
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Quote:
Originally posted by AuroraB
Just to demonstrate my lack of tube theory..
What's a "Mullard Front end" look like ??...
Probably something like this:
http://www.diyaudio.com/forums/showt...337#post140337
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