sheltie dave Posted December 2, 2003 Share Posted December 2, 2003 Guys, went on a search and came across a few great Brook amp references. They actually built a 12a line SPECIFICALLY for the Khorn! Interesting stuff, and obviously PWK had some intense discussions with some of their engineers or vice versa. http://digilander.libero.it/paeng/the_examination_of_the_brook_amp.htm Quote Link to comment Share on other sites More sharing options...
Parrot Posted December 2, 2003 Share Posted December 2, 2003 Thanks, Dave, a lot of interesting info there. Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted December 2, 2003 Share Posted December 2, 2003 Likewise. I wonder if a guy could get the needed trannies for this. Anybody got any suggestions? I'm interested in building this. It's P-P though, not SET. Tom Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted December 2, 2003 Share Posted December 2, 2003 You might want to grab a pair of old UTC LS55 which will be perfect for this amp. They pop up often on eBay. You might also consider the Peerless 20-20 reissue by MagneQuest. The SA-240 would be the one needed for cathode bias. The SA-245 would be best suited for fixed bias. Hammonds 1615 or 1645 would be OK if you want to remain on a budget. Quote Link to comment Share on other sites More sharing options...
rigma Posted March 23, 2004 Share Posted March 23, 2004 Here is the schematic for the Brook 12a. I don't remember where I got it. Hope this helps. mb Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 23, 2004 Share Posted March 23, 2004 How does one know that the schematic in the Link Dave provided is the speacial Khorn version ? Craig Quote Link to comment Share on other sites More sharing options...
Guy Landau Posted March 23, 2004 Share Posted March 23, 2004 This is the standard version. More info on Brook amps can be found here: http://community-1.webtv.net/KerrB/VINTAGETUBEAMPHORN/page3.html Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted March 23, 2004 Share Posted March 23, 2004 Tom: Electra-Print Audio also does transformers for push-pull triodes. They can also wind to a customer's specs/needs, so where there is a will there is a way! I've also seen some promising looking schematics for PP2A3s and 300Bs in VTV. Quote Link to comment Share on other sites More sharing options...
Clipped and Shorn Posted March 24, 2004 Share Posted March 24, 2004 so assuming you buy the xfrms on eBay or whatever, what is the estimate for making a new pair of these clones, not counting labor? c7b9 Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted March 24, 2004 Share Posted March 24, 2004 ---------------- On 3/24/2004 12:06:10 PM Clipped and Shorn wrote: so assuming you buy the xfrms on eBay or whatever, what is the estimate for making a new pair of these clones, not counting labor? c7b9 ---------------- It will depend on which parts you choose. For sure you'll need a plate choke for the driver (T2 on the schematic). These might be costly unless you choose the Hammond line of PSU choke and use them as plate choke. I'd like to know the inductance value of the drivers plate choke though. It may or may not be in the range offered by Hammond. If you go with monoblocks figure between say $600 and $1200 in parts cost/chassis, depending on how crazy you go. I'm assuming you are not using parts from the junk box and are not using generic parts. I'm also assuming you are having your chassis made (classic wood side with copper top and bottom plate). I guess you can lower this price to something like $300 or even less if you make your own chassis and use "generic" parts (i.e., carbon film resistors, cement wirewound resistors and oil caps from any surplus store, Power thansformers and old Black Cat Sprague capacitors from any old coot doing ham, etc...). In a sense, this option would go well with the spirit of this amp as it ain't using "audiophile approved" parts. All these prices are excluding the OPTs of course (and the tubes and the workmanship...). Building the same circuit can cost anything from peanuts to an indecent amount. In this actual circuit, somethings tell me it would be worthwile not to skimp on the iron quality. But I'm partial to plate choke loading so I have a soft spot for this amp. Quote Link to comment Share on other sites More sharing options...
sunnysal Posted March 24, 2004 Share Posted March 24, 2004 craig I do not think daves link is to the special k-horn version of the 12a...just the normal 12a, I have been looking for more than a year and could not find the special k-horn version (12a-k1) yet...guy´s link show some text about it..."The new plan is to follow a circuit that Paul Klipsch developed to add another OPT ( of course without cutting any holes or making any permanent changes ) to each unit and turn them into two-channel amps with seperate, dedicated, tweeter and bass OPTs -driven by the single pair of 2A3s in each amp. RC networks between the OP tubes and the transformers will provide adjustable crossover points. Along with level attenuators on the seperate sections, the two-section amps should make good flexible triode amplifiers for the Vitavoxes. Total elimination of crossovers after the amp. No phase shift. Clean and simple"...maybe jeff could build an amp based on this idea????? regards, tony Quote Link to comment Share on other sites More sharing options...
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