Preamp and impedance question

Just keep waffling on, because you still can’t see the forest for the trees.
https://i.pinimg.com/originals/7b/df/d9/7bdfd904dbe2ff73b9de8b8f7d84563d.jpg

I have not even once changed what I have wrote about EPDR. I have addressed your specific arguments in every case, while I have yet to see you make even one deep technical analysis w.r.t. the discussion  you raised on EPDR.  I have also used my own words, while you have only linked to articles.  Would you like some Maple Syrup with those waffles? Perhaps it will go well with those sour grapes.

georgehifi7,226 posts06-10-2020 1:21amJust keep waffling on,

And this is the reason why Ralph Karsten’s big Atmasphere’s monoblocks that my friend had, could not drive the bass of the "so say" easy load, high efficiency (90db), easy impedance load (8ohms) of the JBL 1400 Array speakers, because of the added -phase angle of the EPDR combination.

I believe this statement to be entirely fictional. Our bigger amps (MA-2 and MA-3) drive that speaker with ease, although I would hesitate to call it an 8 ohm load. A customer of mine has that speaker and having spent a week at his house, I can say the two work very well together. He owns the MA-3s, but the MA-3 has a unique bank-switched power tube setup that allows you to shut off 1/3 or 2/3rds of the power tubes (such that they are not even lit up) thus allowing the amp to run with much less power. The speaker and the amps worked fine together in all three modes.


Tubes are a bit different from transistors in a number of ways as we all know :) One of the ways they are different is the Safe Operating Area (SOA). With tubes you can exceed the SOA without damage to the tube if the tube is allowed to cool off afterwards. A tube dramatically overtaxed, such as in a loss of bias, can turn cherry red from heat, but if allowed to cool off, and the problem corrected, can continue to give normal service. You simply can’t do this with semiconductors- Very Bad Things happen- exceed the SOA and the device is likely damaged immediately! Now the output section of the MA-1 amplifier (140 watt monoblock) can sustain enough current in a pinch that it can easily knock out a 15 amp circuit breaker in the wall. Of course we fuse the amplifier in such a way that this can’t happen in practice, but the interesting bit is that in this situation, while the tubes are obviously outside their SOA, they can survive this sort of thing easily.

During WW2, To get more power out of an 807 (which is basically a 6L6 with a plate cap to prevent arcing), some transmitters placed the tube in a water jacket to cool it- and thus got an astonishing amount of power out of it (around 500 watts- but keeping in mind it was also class C). So this concept is well-known and been used to advantage for a long time.


This simple fact is why a tube amp can drive loads that you would not expect possible (which is why the later Wilsons, despite their low impedance in the bass, seem to work fine with our gear). I’ve had to learn it through experience myself- when I was first approached decades ago to see if our original M-50 (immediate predecessor to our M-60) would drive a Quad ESL63, I thought the amp would fall flat on its face. Turned out to do the job quite well- better than an RM-9 owned by that customer.


Obviously this phenomena isn’t limited to our amps- all power tubes have this aspect of a ’soft’ SOA. So this Stereophile article seems to have more relevance to solid state amps, where semiconductors are simply going to punish you with failure if you don’t observe their limits.

I believe this statement to be entirely fictional
Obviously this phenomena isn’t limited to our amps
So this Stereophile article seems
I believe this statement to be entirely fictional.

Ralph’s gone into product protection mode.
I shouldn’t have use his amps as an example that couldn’t drive those JBL’s 1400 which IS fact and not fiction, "which even he agreed on" way back on the 9-17-2019 and here’s the proof! Ralph's answer https://forum.audiogon.com/posts/1804702 to my post before it https://forum.audiogon.com/posts/1803629
Your slipping Ralph, "one should always remember what one said no matter how old before saying the opposite" Confucius.

And these words "phenomena" "I believe" "seems" are also words that snake oiler’s, and voodoo’ist use, so as not to be held to account, a certain boutique $$$$$ fuse company use them a lot

I shouldn’t have use his amps as an example that couldn’t drive those JBL’s 1400 which IS fact and not fiction, "which even he agreed on" way back on the 9-17-2019 and here’s the proof! Ralph's answer https://forum.audiogon.com/posts/1804702 to my post before it https://forum.audiogon.com/posts/1803629
Your slipping Ralph, "one should always remember what one said no matter how old before saying the opposite" Confucius.

@georgehifi 

Uh, George, the M-60 is **not** one of our

big Atmasphere’s monoblocks

as you put it in your post above. The M-60 is our **smallest** monoblock and the S-30 is the only amp we make that is smaller. The MA-1, MA-2 and MA-3 are all bigger than the M-60. I'm not slipping or in 'protection mode',  simply instead insisting on facts. The M-60 won't drive a 2 or 3 ohm load, but our 'big monoblocks' can.


It would be correct in your post above to have said

the **small** Atma-Sphere monoblocks that my friend had, could not drive the bass of the "so say" easy load, high efficiency (90db), easy impedance load (8ohms) of the JBL 1400 Array speakers, because of the added -phase angle of the EPDR combination.

-however to be really accurate you could just drop the bit about EPDR and simply state that the M-60 can't drive a 2 ohm load but we could have told you that, and did. BTW, the efficiency of a 2 ohm loudspeaker with a 90dB efficiency is 84dB- not a good choice with **any** 60 watt amp. 90dB is not 'high efficiency BTW; that's a moderate efficiency. High efficiency would be in the high 90s or higher.