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Old 12th October 2008, 04:57 PM   #1
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Default Looking to build....

Im in the process of building my tube preamp and am thinking on what to do for a tube amp. Im thinking on a pair of 100w+ monoblocs. I have a pair of Klipsch RB-81s to drive.

Can anyone suggest a good schematic or design to build?
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Old 12th October 2008, 05:48 PM   #2
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With speakers of 97 dB efficiency, most people would be satisfied with less than 10 watts, depending on the room size and acoustics.... so you may not need to go that far. A 30-60watt amp is much simpler to build than a 100W amp.
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Old 12th October 2008, 09:10 PM   #3
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Any and all suggestions are welcome.
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Old 12th October 2008, 09:28 PM   #4
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If (as Tom indicated) the Klipsch RB-81s are 97 dB. efficient, Paul Joppa's 102 dB. rule tells us that (SIC) 4 WPC are enough. Deep Class "A" triode wired EL34s will affordably yield more than 4 WPC.

As a preamp (presumably with gain) will be available, the 12AT7 based "El Cheapo" splitter/driver is quite adequate. A 12AT7 and 2X EL34s comprise the signal tube complement of each channel (6 tubes total). Invest in decent O/P "iron". The Edcor model CXPP60-8-4.2K is the lowest grade item I'd entertain.
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Old 12th October 2008, 09:49 PM   #5
AuroraB is offline AuroraB  Norway
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Hi...
If we're talking 30-60, I'm seriously interested,too!
Problem is, which of the many(?) alternatives out there are the "better" one?
( Whithout going to the very extremes, that is....)

EDIT:
Maybe I should add, - since I live and work in one of the "far away" corners of this world, I haven't heard any of the possible alternatives, and most probably won't either....
Only my brothers Cary's and a McIntosh....oh- and a Lumley....
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Old 12th October 2008, 10:48 PM   #6
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Quote:
Originally posted by AuroraB
Hi...
If we're talking 30-60, I'm seriously interested,too!
Problem is, which of the many(?) alternatives out there are the "better" one?
( Whithout going to the very extremes, that is....)

EDIT:
Maybe I should add, - since I live and work in one of the "far away" corners of this world, I haven't heard any of the possible alternatives, and most probably won't either....
Only my brothers Cary's and a McIntosh....oh- and a Lumley....

Dude,

You're not the only Norwegian member here. The other nordic countries are also represented.

Ultra-linear mode PP AB1 EL34s are good for more than 30 WPC. Do you already own a preamp with gain? If so, the small signal circuitry I proposed to this thread's originator will work for you too. OTOH, if you are starting from the ground up, a Mullard style circuit employing 1/2 a 12AT7/ECC81, an ECC99, and 2X EL34s in each channel gives you the makings of a very nice "integrated" amp.

Sowter (England) winds nice O/P trafos. A merger of the characteristics of their model U065 and their model U082 is what the situation requires. You want the more massive "P" core and a 4 KOhm end to end primary impedance. Don't forget the UL taps.

Lundahl (Sweden) also winds good "iron". However, the 36% UL tap on their most suitable model does not sit well with me.
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Old 12th October 2008, 11:14 PM   #7
AuroraB is offline AuroraB  Norway
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Quote:
Originally posted by Eli Duttman

Dude,

You're not the only Norwegian member here. The other nordic countries are also represented.
I'm very much aware of that fact......only thing is, - thre seems to be roughly 1000 miles between them and me.......

And-I'm quite familiar with Lundahl irons......I have spoken to the man himself on a couple of occations. European iron is not my problem, I think. There are several german makers, too.
My problem ( if considered a problem) is that I have little or no time to design or tinker too much..... I just want to build something reasonably good, and being the old geezer ( 55..?) I am, I do like to build it myself. That's most certainly a large part of the fun........
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Old 12th October 2008, 11:38 PM   #8
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I think you are a stellar candidate for a 300B amp. For a more affordable project, triode strap a 6V6/EL84 instead. Eli's amp is also a good candidate, but with speakers that efficient, a single ended amp would be pleasant.
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Old 13th October 2008, 12:24 AM   #9
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Quote:
Originally posted by AuroraB


I'm very much aware of that fact......only thing is, - thre seems to be roughly 1000 miles between them and me.......

And-I'm quite familiar with Lundahl irons......I have spoken to the man himself on a couple of occations. European iron is not my problem, I think. There are several german makers, too.
My problem ( if considered a problem) is that I have little or no time to design or tinker too much..... I just want to build something reasonably good, and being the old geezer ( 55..?) I am, I do like to build it myself. That's most certainly a large part of the fun........
55, geezer? You're a "baby". I wish my carcass was that young.

Are you based up near Narvik or Hammerfest?

You spend the money to buy parts. There's plenty of help here on the design front.
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Old 13th October 2008, 12:32 AM   #10
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Quote:
Originally posted by audiowize
I think you are a stellar candidate for a 300B amp. For a more affordable project, triode strap a 6V6/EL84 instead. Eli's amp is also a good candidate, but with speakers that efficient, a single ended amp would be pleasant.

Klipsch speakers are efficient. However, they seem to do poorly with the modest damping factors available with no NFB SET amps. I suggested Class "A" triode wired PP EL34s, as both sufficient power and adequate damping would be available. A LITTLE loop NFB provides the necessary voice coil control.
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