[floobydust]

 I've been working on the design for this amplifier for over 9 months in my spare time and finally completed one chassis. It's based on Hashimoto iron, Mills and Caddock resistors, Axon capacitors, pure silver wire and is a no feedback design. 5V4G for rectifier, 12AU7 as input/driver and 45 as output. Measured specifications are:

 Output: rated 2-watts, clipping at 2.2 watts
 Frequency response: 30Hz - 45KHz within 1dB at 1-watt output (2.83 VRMS into 8 ohms)
 Output noise: 200 microvolts max
 Signal-to-Noise (measured) 83 dB below 1-watt output
 Distortion: 0.5% at 1-watt, 1.5% at 2.0 watts maximum

Overall view from the rear:


Bottom view complete, sans cover:


Bottom view of amplifier circuit end:


Bottom view of power supply end:


 Comments are welcome... but I have go build another to get Stereo.

 Regards, KM

[JoshK]

Very nice build!    Your layout is tight but clean and organized.  Nice craftmanship.  Obviously this isn't your first build.  What voltage are the AEON caps rated at? 

What speakers are you using this with?  I might have to try Hashimoto iron as well, but I was dissapointed to see only 5k & 8k primaries.  I really need 6,5K for my design. 

What are you using for a preamp to drive this? 

[JimJ]

That's gorgeous

I used Aeon caps in my monos too, really like their quality.

[floobydust]

Very nice build!    Your layout is tight but clean and organized.  Nice craftmanship.  Obviously this isn't your first build.  What voltage are the AEON caps rated at? 

What speakers are you using this with?  I might have to try Hashimoto iron as well, but I was dissapointed to see only 5k & 8k primaries.  I really need 6,5K for my design. 

What are you using for a preamp to drive this? 

 Thanks for the kudos, appreciated. The power supply uses the Axon HighVolt which are rated at 630V. The bypass are Axon TrueCap and rated at 250V. The coupling cap is an Axon tin foil and film and rated at 630V. All critical circuit uses TF020, and other spots MK132 amd MP820. Power supply uses Mills MRA5 for simple stuff and the MR200 for the input stage decoupling and voltage drop. Kimber AGSS used for everything from DC forward, silver-plate copper in teflon (red stuff) used for AC lines and filaments (sans 45).

 My main speakers are modified (by me) Quad ESL 63 US Monitors in lead-shotted Arcici stands. I also have a pair of Hornshoppe Horns for testing and recently built a small pair 10 liter ported cabinets for Fostex FX120 drivers... these are really nice drivers. Working on some other ones soon... F120a and T90a Fostex units.

 Preamp is my own design from the 80's. 5751 tubes in a phono stage, 6072 tubes in high-level stage, regulated supply, DC filaments, all silver-plated copper in teflon and all silver-contact rotaries for selector, volume and balance attentuators. All neatly housed in a PAS chassis. Used my common parts of the day including Roderstein metal-films, TRT wondercaps, AB carbon comps, Mallory CGS caps, etc.

  Regards, KM

[JoshK]

Thanks for the answers...I think I saw in your cross post that it was two stages before the output tube, cause I was wondering how you got enough gain out of the 12au7 with one, which is why I asked what you were using for preamp. 

Does the 45 drive the ESL63's loud enough?  I know they can't take too much juice, but I've never heard them.  I've never heard a 45 SET before and was wondering what they have enough juice to drive.  I have mostly read of people using them with big horns.

[floobydust]

Thanks for the answers...I think I saw in your cross post that it was two stages before the output tube, cause I was wondering how you got enough gain out of the 12au7 with one, which is why I asked what you were using for preamp. 

Does the 45 drive the ESL63's loud enough?  I know they can't take too much juice, but I've never heard them.  I've never heard a 45 SET before and was wondering what they have enough juice to drive.  I have mostly read of people using them with big horns.

 Yes, two stages... as a result, 170mv input drives the amp to 1-watt output. Will be designing a matching preamp later that is better suited.

 At 2 watts max output, you can drive plenty of stuff... just depends on how loud you expect it. The Quads are down around 86dB sensitivity so you can get decent listening levels with much material. They (the Quads) can take a fair amount of signal and will clamp if driven too hard. I normally use 50-watt monoblock push-pull units. The 45 amps can give you a very open and articulate sound within their range. The Quads sound superb with them, but not a high dynamic range option. The little Fostex units do well despite the FX120 being rated at 89dB sensitivity. They get plenty loud for most listening even with the small 2-watt amps. I built a really quickie-simple set of 45 amps using Magnequest RH40 outputs and some old Triad NOS iron for comparisons. These have worked out well with a more classic circuit.

 Regards, KM