How much SET power is enough?

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audiotom

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Re: How much SET power is enough?
« Reply #20 on: 21 Nov 2022, 02:22 am »
Jarbs

Thank you so much for sharing your Apollo 11 real world SET amp experiences. Very enlightening.

Well I picked up a set of 4 vintage RCA UX250 tubes from my friend to hear the SET design optimized.

The other tubes were cheap Super TNT Chinese tubes. He started out with those tubes on purpose without any insight.
He wanted me to hear the SET magic with the poorest of tubes as reference and hear my comments on the sound - particularly limitations

Those Chinese Tubes were Thin filament, low current
They couldn’t reproduce the harder dynamics

There is very strong current flow with the RCAs
The output transformers are TM1 Cobalt and Steel. 2 RCA 6S4 driver tubes

I placed the RCAs in the unit and hello, not only did you hear the mid range magic.
The dynamics were nicely portrayed. Authority, solid core.
The SET textures and presence were enhanced with the new tubes
Volumes, heft, space, soundstage all refined.
More than enough volume.

In the last few hours I put the amp through a series of very dynamic recordings I know well
Ravel Daphne and Chloe Living Stereo Munch Boston Symphony (some symphonic swings)
The Who Quadrophenia Side 4 Track 1st press
King Crimson Lark’s Tongue in Aspic 1 UK first press
Elvis Costello This Year’s Model UK first press
Amongst other things

The unit sounds more than powerful enough to drive the Apollo 11 and has alleviated my initial concerns
I am able to hear strengths of the pentode and the SET amps but both are moving musically.
I am Very pleased with the sound

Thank you

Tom





Jarbs

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Re: How much SET power is enough?
« Reply #21 on: 22 Nov 2022, 02:35 pm »
Tom,

You are welcome. Glad to share when I can. Small payback for all I’ve learned from others who contribute.

Thanks for providing this additional data point about your 12 watt amps. A well executed amp, with oversized output transformers that won’t saturate on peaks and overkill power supplies with ample chokes make all the difference.

I was pleasantly surprised how well the 1.5 watt TM 45 with 10y driver (just two stage) drove the Apollo 11. I did not push them hard, at all. No point in listening to 10% distortion as the quality disappears. This was an 80lb two chassis amp. For 1.5 watts! But in the end, there was too much compromise. This is an amp that deserves a high quality horn speaker.

Considering my room and wide range of music, I will likely always have an SET (or tube anyway) and SS amp. With SET, have enough power, but not too much. The magic occurs at lower output levels. I’m leaning toward Class A for SS, such as the Gryphon Essence. I’ve already done a Pass XA30.8.

Regarding your 12 watt amps, are they parallel SET? You mention acquiring (4) UX250 (same as 50). Can you share more about these amps? PS, rectification, input sensitivity, DF, etc.? Photo?

Thanks,
Greg

Stercom

Re: How much SET power is enough?
« Reply #22 on: 22 Nov 2022, 02:54 pm »
A well executed amp, with oversized output transformers that won’t saturate on peaks and overkill power supplies with ample chokes make all the difference.
Exactly right

rbbert

Re: How much SET power is enough?
« Reply #23 on: 22 Nov 2022, 04:46 pm »
It is very cool that there are so many good options for driving the Apollo 11's.  I was happily surprised to find that going from the Pass INT-60 to XA60.8 monoblocks resulted in noticeable improvement in dynamics, soundstage and bass "clarity".

Tom, did you do the midrange upgrade for your speakers?

Jarbs

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Re: How much SET power is enough?
« Reply #24 on: 22 Nov 2022, 05:51 pm »
FWIW, my Apollo 11 are original 2018 vintage without the mid range upgrade. But I picked up a pair of Poseidon v3 with the mid range upgrade. My wife uses them in the main living room. On receipt, I inserted them into "my" rig in "my" lower level listening area. I didn't notice the usual issues with new speakers (they were v2 initially) so maybe Lou had run them in a bit. But I was surprised how different the Apollo and Poseidon sound. The Apollo are darker with more mid bass. Higher system Q? The Poseidon were more sunny and lean.

This was the most noticeable difference. But I think the Poseidon were a little more coherent through the mids. A little better definition and clarity. It was a subtle difference. Not the same model speakers, but the possibility of getting a true A/B compare outside of Ferndale is remote.

Always wanted to try the XA60.8. Should be plenty of drive for any Daedalus. My XA30.8 had a nice extended low end, wide stage, and extended, natural, dimensional highs.

audiotom

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Re: How much SET power is enough?
« Reply #25 on: 23 Nov 2022, 04:38 am »
Greg

The amps are in parallel - totally separate straight line from inputs on the front to the transformers  outputs on the back
12db per channel,  manual biasing.  I’ll ask for more details
He has it on a board right now - refine the design

I have not finalized getting the Eton  4.5 in midrange upgrade - sending out a bat signal to Lou on the west coast
 

Those Lampizator amps loook very nicethe xa60.8 as well

A_shah

Re: How much SET power is enough?
« Reply #26 on: 11 Dec 2022, 10:55 pm »
Thanks for sharing the additional context, Jarbs. I have a much better sense of what you found lacking in the LM now. I certainly wouldn’t claim the LM 845 sound is the ultimate in resolution or in frequency extension. My Odyssey, Folsom, and now ClassDAudio amps each outperform the 518ia in terms of absolute resolution and frequency extension. But there’s still a rightness and realism to the LM 845 sound that is completely different than any of these solid state solutions, even when paired with my Don Sachs tube pre. And with top quality tubes, you do get ample details and nuance to be holographic and not warmed over/fuzzy - that inner light of the music that good SET reveals, along with the excellent macro dynamics of those 845 tubes.
I have been testing my Poseidon with a single DECware 84UFO 2.3 watts

( own a pair) I find that when sent through my OPPO 205 direct to the speakers seem to be more transparent & resolving than via my Don Sach 2 both the DEcware and Don Sachs have Mifix caps
The IC are Wywire Diamonds probably the best cables that I have encountered for my particular system
Asghar