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The point of an 845, 211, 805 amp?
The point of an 845, 211, 805 amp?
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Old 26th June 2019, 11:43 PM   #31
Zoran is offline Zoran  Serbia
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Yes, BUT it can sound a much better. All You said + bonus, huge BW, deep clan natural base, highs with a "root" in the middle, Voices - real and beautifull. And that "Air" and "flow". A way better than ordinary SE OT designs...
I like 10Y SE design
(with good and not-easy-to-built OT. (ofcourse other things have to be coorect too, driving Dynamic capacitances, power supply extra care...)

Hi Waveburn
true, but it is only cloning of tube parts and sch as is. All other materials are different because these days is hard to find, and "standards" are changed... Power transformers then was better. Better calc and better lamination's and isolation. Even wires are not from the same quality. OT was a bit short, but only because a different BW standard. PiO Cs was also from smaller values. Theese days power Cs in the Amps are so huge?
BTW I like mucho Your original approach, and many unique designs You presented here...
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Old 27th June 2019, 04:46 AM   #32
samsdad is offline samsdad
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I know this is DIY, but for those of you who consider these type of amps superior to the beam tetrode/pentode type tubes, do you have any recommendations as to manufacturers whose amps are worthy of a listen and are reasonably priced?

The aforementioned Berning amp apparently is some $75k, and thats well beyond my price point. Id have a really hard time considering anything north of $10k, especially if it required a separate preamp.

Has anyone heard one of these line magnetic amps that can chime in? If I recall, Stereophile ran some tests that shows ringing on the square wave of, I think, the line magnetic 518ia. Would something like that throw a red flag for you?

Also, is there any ABX tests that anyone can point me to that shows a preference to transmission-tube amps?

And finally, yes, I understand that distortion numbers are at the end of the day meaningless if you dont like what youre listening to. On the other hand, Im not interested in procuring an amp that sounds great with Getz/Gilberto but turns to mush with Beethoven because the IMD is off the charts, etc.

I appreciate your input.
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Old 27th June 2019, 05:37 AM   #33
grovergardner is offline grovergardner  United States
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Actually, that was a pretty good review from Stereophile. A good SE 845 amp is not something that only sounds good with acoustic guitar or Stan Getz. It can do Mahler equally well. You might consider the Line Magnetic 845ia. It's a good-looking design that uses an EL34 driver. It's around 5K euros. There are a number of Chinese SE 845 amps on eBay that use a 300B as driver. I can't vouch for them. $1200 seems like a bit too much of a bargain, but Chinese amps can fool you. ;-).
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Old 27th June 2019, 12:49 PM   #34
Bigun is offline Bigun  Canada
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The point of an 845, 211, 805 amp?
the filament power for one 845 is enough to meet all your music requirements !
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
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Old 28th June 2019, 06:03 AM   #35
Chris Hornbeck is offline Chris Hornbeck  United States
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I built my 845 amplifier in 1994, the era of _Sound Practices_, where I first saw their curves, so can claim to be a true fashion victim. Used the huge and impressively ugly Audio Note 10K Ohm output transformers of the day and paralleled sections of 6SN7 drivers. Today I'd opt for a triode-connected EL84 driver, but today I wouldn't bother.

The linearity of the "50-watters" is available from triode-connected sweep valves, with added advantage of more manageable drive voltage and transformer impedance requirements. If you don't get drawn into a numbers race for power output (sadly common on DIYaudio where it's *least* important) you can lightly load as many sweep valves as you feel you need and get as good or better linearity. Buy a lifetime supply of valves - there won't be any more made.

WRT the higher mu valves in the thread title, Zoran has already covered the output transformer difficulties well, but to put an even sharper point on it, zero bias triodes are effectively useless for audio outputs. Yes, people do it. But no, it's stupid.

Type 211, with a mu of 12, could be used with some theoretical 15K Ohm output transformer, but the transformer is a serious bottleneck. Three valves in parallel get us into the just barely practical (in a biased core transformer) 5K Ohm range. A single type 304TL could be used here also, at lower cost and excellent linearity. (But you'll need to learn about re-gettering them.) But try sweep valves first.

All good fortune,
"A marveilous newtrality have these things mathematicall and also a strange participation between things supernaturall, immortall, intellectuall, simple and indivisible, and things naturall, mortall, sensible, componded and divisible." - John Dee
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Old 28th June 2019, 04:53 PM   #36
hpeter is offline hpeter  Slovakia
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....because you can ? or bragging rights.

look, i just replaced 2a3s in my simple amp with trioded 4-125
far from optimal, but works... it sounds different, more detail i can confirm that !
..BLOG.. XMOS_U8/PCM5102A > LL1544A > 6H9C+gyrator > 2A3_SOV/JJ > LL1660 > STAX SR207 _ SR L300 _ SR007 # LL2748 > 394A > LC 12H/1000 // 4-125a test
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Old 28th June 2019, 06:52 PM   #37
SpreadSpectrum is offline SpreadSpectrum  United States
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Sometimes there is no point. I used an 841 to get lots of linear voltage swing as a driver for my Unity-Coupled amp. I later developed a pentode driver that has two orders of magnitude less distortion but the 841s stay, because they sound good enough and they look awesome.
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Old 28th June 2019, 07:49 PM   #38
dhaen is offline dhaen  Europe
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Originally Posted by SpreadSpectrum View Post
.. because they sound good enough and they look awesome.
You make a good point. The listening experience is more than the specs.
This is why it's more satisfying to clean an LP, align and lower the stylus than inserting a CD.
likewise, inserting a CD is more satisfying than clicking a mouse button.

Sit in your comfy chair, pour your favourite tipple, listen to the music and watch the glow.

It's the overall experience that matters.
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Old 29th June 2019, 10:34 AM   #39
Guerilla is offline Guerilla  Denmark
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@Tubelab Pics in #12; Rock on! Someone will really enjoy that thorough groundwork on the car.

@Wavebourn #30 is really well put.

Would someone kindly sum up, what is a magnetic amp and what is interesting about them?

Edit: maybe Magnetic line amp is just a brandname?
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Old 29th June 2019, 08:18 PM   #40
grovergardner is offline grovergardner  United States
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"Line Magnetic" is a brand of amplifiers.
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