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  • Jr. Member
  • Posts: 39
« on: 29 Jul 2006, 09:45 am »
I've been reading your blog everyday, its very interesting.
I'm realy excited that you refisit the CLARION project. I have fostex horn and naturaly SET is their partner.
I got more excited when I read its about $600 in total... Whoa, finaly Bottlehead Paramour has some competition. See, I've been searching for good inexpensive SET kit and the only kit come under $1000 is from  Bottlehead.
Could you elaborate more about this project? circuit topology? etc, etc.



  • Facilitator
  • Posts: 2274
« Reply #1 on: 29 Jul 2006, 10:17 pm »
It's about $600 in parts for a 2-channel amp.  Maybe a little more when I'm done with it.  I like to tweak the most of out a design.  It's a pretty straightforward amp.  Probably similar to others you have seen - I don't know, didn't look around.  I just did it from scratch without investigating anyone else's work.

The CLARION uses a lot of iron.  Big power tranny dumps into a 5AR4 into 5H choke and 200uF for rectification.  That gets rupple down to about 1/4V.  Then another LC cleans it up for low hum on the output stage.  Another RC supplies the driver stage.  Channels are split after rectification.  All LCs are tuned for critical damping.  That is, fast transient response with no ringing.  No, it does not use drlowmu's minimal ESR.  It uses a calculated optimum R, which is nonzero.  Anyway, the 2A3 run's a bit conservative at 60mA and 240V.  The 6H30 super-linear driver tube (I keep changing it) provides a low impedance grid drive.  Gain is low, so you'll need an active linestage to drive this.  My guess is that it might need about 2V input for clipping.

My only unique contribution here is the use of incandescent lamps.  I use one in each 2A3 tail to indicate bias (working or not), one for 6H30 heater.  Then two more on back panel.  These are used to drop the 120V nominal ac line down to the specified inputs for the Hammond trannys.  One is rated for 117V the other two for 115V.  Therefore, the lamps drop the primary voltage to nominal, work as a fuse, and also provide the resistive half of an RC low pass filter.  Essentially, I get four benefits from adding the extra lamps.  Unless I screwed up again, the lamps should make for quieter and lower heat operation.

I did a preliminary chassis layout.  Fits into a 17 x 10 box.  Two chokes and two trannys inside, one power and two output trannys on top.  Has a nice look to it.  But it's not total sculpture, as I have screw heads showing on the top for the under mounted iron.  I already have most of the parts, from my original CLARION design, which was supposed to have used ultrasonic heating.  Just need to cut me a chassis and build.  It will be my backup amplifier at RMAF, in case the Azzolinas prefer something less powerful than the CYMBALs.  You know how it goes, amplifier <> speaker synergy is very important. 

Not sure if I will turn this into a product.  Might just publish parts list and be done with it.

jh :)