Noise Duality 300B Amp. Pics attached.

Tell me that huge amp isn't just for headphones...I'm getting the sick nervous feeling inside that it just might be.

I think it is.

This is a speaker and headphone amp - I believe tjkurita mentions it in his review, and you can see the bananaplugs exit the speaker terminals in his picts. I'll let tjkurita speak more to his speaker experience with it, as I only heard it with headphones (though that includes my K 1000 out of the speaker taps) at the national meet.

Best,

-Jason

I've been listening for about 5 days now. It is really, really great. Especially through speakers. The question of imaging is answered. After a little bit of speaker placement (and clear ears) the "in the head" imaging is there. Instrument placing is precise and 3 dimensional.

I have found that the tonal and dynamic response seems limited only by the source and the speaker.

I don't really have anything else to say about it. It sounds better than anything else I've owned.

Hopefully Blackie will get his designer's notes up soon and all questions will be answered.

I heard this amp at the national meet & it just blew me away(Wallet also jumped out of my pants pocket to run & hide ),This is a very special amp,It made the Hd600 sounds better then it had a right to,could have used a little more impact in the bass(maybe some tuberolling would help),bass it had was taught & well defined.Soundstage & detail where right with the best I have heard.
Congrates to john on the Amp & Kudos to Blackie for building it.
If I am ever in the market for another amp ,Blackie will be hearing from me.

That is one very cool looking amp and power supply!

And all the comments thus far have been glowing too.

Price wise: What is the ballpark cost?

just some background for y'all...

the takeoff point for my design process on any custom build is time i spend with the buyer of the piece. it's a damned unpredictable thing, that initial inspiration. sometimes i can ask someone 2 questions and look at them hard and i suddenly know exactly what to build for them. other times i am stumped for a while. it happens when it happens. with the inspiration comes a burst of energy and an overwhelming desire to build it. that's how i know it's right.

the inspiration for this particular build came from a long conversation with John Kurita about life, and some of the staples of a rewarding life: marriage, music, a sense of permanence within a flexible frame, and the importance of individuality within a harmonious union of very different elements, and the dynamic tension that embodies, and the fearless idealism required to do... anything really fun

note that the amp is full dual mono, from the twin power cables forward. rather than do monoblocks i prefer a separate audio and power supply chassis.

the components stand equal to each other, and share a common ground path, the original source of electron flow. they are arranged with the shortest signal path possible. it's very traditional in many respects, especially compared to some of my other builds, but with enough original touches to keep it interesting. this design value mirrors our conversation. i felt it would make john happy for a very long time. i wanted to make him his last amp, as idealistic a goal as...marriage.

this amp is a true chopper, nothing superflous, all parts very high performance. black gates, polypropylene-in-oil-bath filter caps. some nichicons. solid fine silver signal path wiring. low inductance wirewound resistors. a carbon-comp or two for flavor. solid copper chassis and binding posts, and really killer chokes pulled from an old military power supply i bought one day at a hamfest in central jersey with one of my closest friends, jc morrison. we bought 20 blackplate rca 6sn7's that day for $5 (total!) and we were having so much fun we forgot them

no faux anything, no thin plating, nothing gilded, nothing chromed.

the sonic goals in designing this amp: clean, clear, honest, wide-band, low dynamic distortion, stable, durable, totally unflappable. Not wet, not dry, not warm, not cool, not big or small, not front or back ... like clean, clear, running water, a good marriage, a staple.

the 300B is probably the most linear amplifying device ever designed. in SE mode it will yield more than enough power for any set of cans, and a great number of speakers as well, with no evil tricks or undue circuit complexities necessary. likewise the 6sn7, clean and true at the right operating points.

the truth is, all amplifiers distort at all times. as do our ears. and we are far more sensitive to some distortions than others.

it's all about choosing the spectra of those distortions. we can shoot for a close match between inner-ear distortions and electronic distortions, and achieve our sonic goals. the 300B is LOVELY for this.

(see attached research paper for some significant in-depth musings on this only-marginally-measurable art...and see the attached western electric data sheet, where you will witness firsthand that the engineers who developed this primo audio tube were VERY concerned with the low-order distortion spectra at different operating points and loads, which they exhaustively charted...)

http://www.tubesville.com/cheever_thesis.pdf

http://www.tubesville.com/300A.pdf

operating points in this amp can be chosen by tube-rolling to shift the distortion spectra, which it was fully designed for. it can use 5u4g, 5u4gb, 5r4 or any 5r4 variant (i fitted it with kickass mil-spec 5r4wgy's), 5ar4 or gz34, hell even 83's for you mercury vapor sniffers
any reasonable 300B type can be inserted as long as it meets full western spec as published in the data sheet....

re: bass...it's my feeling that in a high-performance amp, bass should be detailed. between 20 and 500 Hz there are a million and one shades of meaning and all of them should be absolutely clear and present. a high bandwidth (both extremes, for transient accuracy) and a very good output transformer are key to this.( one of the best sounding amps i ever made was a SE parallel pentode amp with cheap guitar-amp quality electrolytics and caps...but it had a clean bandwidth from 5 hz to 80 khz because i used a really awesome transformer. i can only imagine what it would have sounded like if i had sprung for better parts hehe.)

in the course of repairing and tweaking many commercially made tube amps, i have observed this as a shortcoming. the waveform often falls apart below 50 hz due to transformer compromises, yielding a thick bass with a one-note resonant quality. the way the amplifier couples to the transducer is also super important to the low end, especially with a no-or-low feedback amp. different transducers give very different results as a given design will control each driver differently, especially at the higher excursions. the best way to deal with this is to design systems starting with transducer and working backward...

i would like to thank you all for taking the time to critically listen to this build. nothing is more valuable than having a bunch of ears and eyes check out your stuff and tell you what they think. your impressions are most welcome.

thanks again

-blackie.

That post made me feel very passionate.

Thanks for posting it.

Good stuff blackie, i wish i could get a chance to hear one of your designs.

Blackie, thanks for the design notes. You've created a fantastic piece of work - one that looks as good as it sounds and vice-versa.

I heard this amp over the last weekend. If you had asked me over a year ago, when I found out this project was comissioned, whether this would be as good as it turned out, I would have said, "unlikely". I'm pleased that my expectations have been so thoroughly surpassed.

Best,

-Jason

That was a great write-up Blackie and quite a good read too. Thanks for sharing.

Amen to what blackie said. We need more post like that around.

Thanks for the write up Blackie look foward to hearing and seeing more from you, it such a beautiful amp. I wish I had the opportunity to audition it.

http://www.stereophile.com/news/042406heaven/

sorry, guys, i just couldn't find a place for a logo, and no, that ain't plating...it's solid electrical grade copper hehe

i love that john was playing a mono recording. that is extremely awesome!!!!

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haha! Lester Young really does sound good through it!