Cadence and Jochen Semler

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bombaywalla
Stammgast

#51 erstellt: 03. Sep 2006, 04:17

screamgigi schrieb:

Bombaywalla-ji

I listed my ideal points for SE and PP. The propah audio choice, again IMHO, would be both. That sentence addresses both the topologies.

However, the ultimate hi-fi choice would be SE 45, 50 or 2A3. I have heard all of these tubes. It helps that I have a big stash of these. All bought for approx Rs. 35 to 100 in military, railways and DOT surplus sales.

Ironware:
Yes you are right. OPT,. PT and Chokes have the most influence on tube sound. Caps, wires even tubes are secondary. And good iron usually is expensive. So if you expect to hear magical sound in high power tube amp, be prepared to pay high $$$’s. I would be wary of picking up a $500 amp that promises 70 watts.

Damping:
Yes you are partially right, but folks have widely differing opinion on this. For instance a Class AB Push Pull Pentode/Tetrode may like to see a highly damped speaker. A SE Triode amp is ok with a low Q speaker.

That brings us to the question ‘exactly what is damping? In most basic explanation it is the ratio of the speaker impedance and your amp source impedance. How much damping? Some swear anything less than 200 is unaccptable. Some are Ok with 100. Some are ok with 20. It all interwines very finely; your amp, speakers, wires, music, etc.

There is an additional aspect. Damping factor reading is usually taken at high outputs, but at lower output most amps will demonstrate a DF which is at least 5~10 times lower. This is particularly true when Class AB Push Pull amps with a low standing current are involved. This phenomenon is somewhat absent in case of a Class A SE triode amp thereby reducing the impact of DF in our listening experience. A typical SE Class A will be a have DF of 20 or so. A case of less is adequate.

Screamgigi,
your comments are taken in the correct spirit by me.

Yes, the topic of damping factor - we can have a raging debate!

A case for another thread - needless to say.
I agree w/ you that the numbers for adequate DF varies all over the map! Suffice it to say that you have written a good succinct version of the (raging) debate.

bombaywalla
Stammgast

#52 erstellt: 03. Sep 2006, 04:27

[quote="Amp_Nut"]

Would love to hear any other 845 based amp...
Is The Anybody Out There ?
[/quote]

yes, I've a friend who owns a Bel Canto SET40i driving his (custom) line-array speakers. This amp uses the 845 output tube. Absolutely beautiful sound! More so now that he has had several internal parts upgraded to better quality.
The spatial separation in the soundstage is like none other I've heard from PP tube or s.s. amps.
Yes, Screamgigi is right - that 845 tube is actually a radio transmitter tube (adapted for audio use) hence it's plate voltage can be as high as 1200-1500V! I don't think that the SET40i uses that high a plate voltage - I think that they use 800-900V.
This SET40i is worthy of consideration however it is slightly on the expensive side even used. it puts out 40W/ch but don't let that fool you. If you have a relatively easy speaker load, it'll drive that speaker w/o any issues.