40+ watts SET, cost is not a problem

I have been down this road many years ago and found a place where I have remained settled throughout the years since the end design for the Commission Built Amp's have been realised.

In my early days of Audio System Building, I migrated from SS to a Valve Pre Amp and PP Power Amp.

After the Honeymoon period, I ventured into the world of Valve equipment very deeply and was influenced by the SET Designs > Horn Speaker / Cabinet Speakers I was encountering. Following the profound experience a Tim De Paravicini Demonstration had on me, a whole new way of thinking about how I was to move forward appeared.

I was very much more aware of the Speaker Type I wanted to continue with, and how I wanted these to be driven.

I took the discussion to a very experienced Valve EE, and the Journey was embarked on to what was to become bespoke built 845 PP Monoblock Power Amp's.

These are a design optimised for the 845 at a 25 Watt Output, (following description might be a little off, its been a while), they are Class A, Linear, Feedback used ?? Point to Point Circuit with Hand Wound Power and Output Tranx.

At the time of these being produced there was little like them on offer as a Product, and one Brand was offering a 211 Monoblock @ approx' £50K.

I have not heard many set ups that can produce Headroom like these Amp's and have compared them to other Amp's over the years, they have always remained very impressive, and really get the best out of all Speakers met to date. 

The Thread in the Link, has covered the design / build of a 300B as a joint venture between two time served EE's specialising in Audio Equipment.

A offer has even been made of a very late in the development prototype, that would be a great experience, and possibly one that may be a keeper as I have found with my own experience.

nin  

Pani,

Your speakers are not exactly easy to drive at 85db 4 ohms. I'm going to echo what many have already said, and that is you night not be happy with a SET amplifier.....you may have to drive it hard to get what you are looking for, and that may take the "magic" out of a SET amp.

You have some really good recommendations, and I'll add one more. I'd give Aric Kimball a call at Aric Audio (Google search for information), to get his input. He gives very freely of his time, and sells a bunch of amps you may want to consider: a couple of 300B amps, a 2A3 amp, the Transcend "Push Pull" (is what I own), a KTand a pair of monoblocks.....several might be excellent for what you are looking for. He also loves custom builds, many of his current lines started out as custom builds

I know you said no solid state, but at least look at the specs of the CODA S5.5 class A SS amp......I have had one for about a month, and it's truly amazing; huge current delivery on hand

@brandonwade ,

Tap any post and a ’report this’ icon will appear. It will tell you to select a reason it should be deleted. One of those reasons is ’it contains profanity’.

Your foul language is against forum rules.

Capeesh?

"What’s most disturbing is voicing a $30k Amp through a pair of Tektons…."

😂

I have owned a 300b SET for 15 years and simply love it. However any DHT can be utilized in a SET amplifier. 2A3, 45, 211,805,GM70 etc. SET is not limited to300b.

@charles1dad 300b is about as powerful as you can get and still claim hifi bandwidth. The thing is, if the amp doesn’t employ feedback, you’ll get phase shift down to about 10th the upper cutoff frequency (-3dB point) and 10x the lower cutoff. This is filter theory.

The ear is terrible hearing phase by itself, but over a spectrum it can interpret it as tonality.

Phase shift in the bass due to a cutoff frequency not low enough is audible as a lack of bass impact. Phase shift in the highs due to a lack of HF bandwidth is heard as a darkness. So you need bandwidth well beyond the audio band to really get this part right; with no feedback ideally 2Hz to 100KHz or better.

@atmasphere @charles1dad @jond and others, it seems people are not warming up to the idea of SET here. And also there seems to be very few seriously good tried and tested choices beyond 25 watts. So what are some really good options for push-pull tube amps operating in class A with zero negative feedback?

@pani There is nothing wrong with feedback if its properly applied! The problem is, it usually isn’t. As a hint you can’t apply it to the cathode of an input tube since that tube will distort the feedback signal. That will cause IMD and higher ordered harmonic generation, both of which are not musical. This is one of the reasons feedback has a bad rap, but its not feedback’s fault so much as poor execution.

An advantage of zero feedback though is you get a ruler flat distortion vs frequency curve. This is important; if there is a rise in distortion at higher frequencies the ear will interpret that has harshness and brightness because the harmonics will not be masked (as they usually are in an SET). I know a PP amp that is zero feedback isn’t that hard to find. Take a look at the ’300b lovers’ thread on this site.

If you do feedback correctly you can get a ruler flat distortion vs frequency curve just like a zero feedback amp, but with lower distortion overall; just as smooth as any zero feedback amp, just as laid back, but with greater resolution since distortion obscures detail.