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Non-strapping, Gives most relaxed sound (as in least forward) and includes most ambience as well. Should work well with every heptode.
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1/7, Includes more treble bias and can reveal more detail. Depending on tube you could loose depth of stage resulting in a more forward sound. A good way to make the tube "more engaging".
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2/7, This is ambiguous for me. A total no go for the Tung Sol 6BE6 (bass crazy), not too much effect for the 6A6P, quite nice with the Amperex E91H - that's just me
(more treble, more engaging, more forward).
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EF91/92 (= 6/7 or 5/7), so far hardly useful strap for most tubes. For 6BE6, it yields more treble but lesser ambience and overall doesn't sound balanced. Having have said that, the 6A2P I have is quite bass heavy and with not too deep stage, so this strap actually could do something good.
A11, nice, precise post, as usual!
Let's see: I think the way you describe the "effects" -perceived and described by everyone here but obviously quite subjective- is very close to the "pattern" I hear, as far as the 1-7, 2-7 and EF92 settings go.
- 1-7 always seems to yield some degree of high-end emphasis; not necessarily more treble
per se, or more treble than unstrapped, but definitely more
perceived detail -usually. I personally like that setting on most 6BY6 types, though I am having the worse time making up my mind whether or not I could live with it as my permanent go-to setting.
- 2-7 -which I admittedly have only tried on one pair of tubes- feels, imo, a bit more relaxed or laid-back somewhat; not by lack of focus or detail, but just by seemingly "taming" some of the rougher aspects emphasized on the 1-7 setting. An interesting setting, worth a try, but I still prefer the 1-7 or unstrapped setting up to now. Try it and help us make up our minds lol. I realize that I'm increasingly straying away from a preference for a laid-back sound and more towards clinical precision and ultra-detail with time though, so I may be biased -but aren't we all though?
- Unstrapped has never sounded bad on every heptode I tried it on. At worse, like on 6BY6 tubes, it sounds a bit less high-strung than with the 1-7 mod, and more relaxed, though not always less forward (my Tele EH900S are just as forward on both settings); and at best it sounds natural and effortless, hardly a bad setting to try. Consensus does seem to be in favor of this setting for 6BE6 type tubes. I can't quite say I feel the same about ambience, though I understand exactly what you mean A11. I do feel that the sound is wetter and more "physiological" or natural, but I find I hear more "recorded ambience information" along with the extra perceived detail and soundstage with the 1-7 mod -on 6BY6 tubes.
- EF92 setting has been horrific in my experience, it disgusted me of heptodes for a month... Still worth testing, if only for reference though; and you never know when you find a setting that works well for no reason , right?
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Lot of (2) Vintage TELEFUNKEN EH900S E91H Audio/Radio/Amp Vacuum Tubes
http://www.ebay.com/itm/Lot-of-2-Vintage-TELEFUNKEN-EH900S-E91H-Audio-Radio-Amp-Vacuum-Tubes-/400405173654?pt=Vintage_Electronics_R2&hash=item5d3a021596
And after looking at these more closely, "Made in Germany" is not printed on the tubes. And further, in the middle picture, you can see the Philips Heerlen, Holland factory code (the triangle that looks like the number 4 with the bottom cut off + 9A4) so these are, in fact, Philips/Amperex E91H, manufactured in the 4th week of January,1969, relabeled as Telefunken.
In the end, I am very happy I didn't get them. ahaha...
Edit: Rather than a boycott, I think it would be a hoot if he were to receive a bunch of offers for $1 or $2 a tube.... But of course, I could never suggest that anyone actually do this! ahaha..
Gibosi, if I'm not mistaken, I think you can see that the tubes are also longer than regular EH900S or 5915 special quality 6BY6 type tubes; about as long as Heerlen E91H fact lol, so yes, I'm pretty sure these are what you think they are!
I'll take this opportunity to encourage all of you to try and pick up a pair of fake-Tele labeled EH900S made by Sylvania and dual-labeled 5915, as these are still my favorite heptodes along with the E91H. Mine came in Tele boxes with military tags, Tele logos on the tubes, 5915/EH900S label, and Bundeswehr "eagle" marking. Regular US 5915 might be perfectly identical, but these should have been somewhat selected, seeing that they're rated for 10K hours and still mil-spec.