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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 30th June 2019, 01:18 PM   #41
Mark Tillotson is offline Mark Tillotson
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Quote:
Would someone kindly sum up, what is a magnetic amp and what is interesting about them?
Cheers!
Wikipedia has already done this.
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Old 30th June 2019, 09:54 PM   #42
analog_sa is online now analog_sa  Europe
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The point of an 845, 211, 805 amp?
Quote:
Originally Posted by samsdad View Post

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


And if you really want to buy an amp, why ask on a diy forum, rather than Agon?
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Old 30th June 2019, 10:26 PM   #43
Bigun is offline Bigun  Canada
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The point of an 845, 211, 805 amp?
+1


jeez, surely it’s just a simple case of - big tubes are fun, nobody need have any other reason !! just build !
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Old 1st July 2019, 12:36 AM   #44
samsdad is offline samsdad
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Quote:
Originally Posted by analog_sa View Post
Trolling? Just a tiny bit?


And if you really want to buy an amp, why ask on a diy forum, rather than Agon?
Not trolling, really. I’m asking here because you folks know about circuits; know what works and what doesn’t; know what is crap and what is worth spending money on. If it’s anyone whose opinions I think are trustworthy, it’s yours. There’s so much myth, puffing, etc. in the HI-FI world that sometimes it gets to be too much.

As far as the ABX comment, again, I’m just curious if there is a “generally accepted” superiority to these types of tubes.

From what I’m gathering so far, the consensus is “yes” they are generally superior—visually, and “perhaps” sonically, but “generally” not really.
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Old 1st July 2019, 02:12 AM   #45
grovergardner is offline grovergardner  United States
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Quote:
Originally Posted by samsdad View Post
Not trolling, really. I’m asking here because you folks know about circuits; know what works and what doesn’t; know what is crap and what is worth spending money on. If it’s anyone whose opinions I think are trustworthy, it’s yours. There’s so much myth, puffing, etc. in the HI-FI world that sometimes it gets to be too much.

As far as the ABX comment, again, I’m just curious if there is a “generally accepted” superiority to these types of tubes.

From what I’m gathering so far, the consensus is “yes” they are generally superior—visually, and “perhaps” sonically, but “generally” not really.
If I were to go seriously single-ended again, I would not be happy with anything less than an 845. The 300B would not do it for me in the long term. There's a richness and weight to the music that the 300B, as lovely as it is, just can't match.

That said, I switched to PP triodes a while back and I probably won't be going SE again. I'm just applying the finishing touches to an "original" triode Williamson amplifier, the famous "Musician's Amplifier," and it affords the beauty of SE with far better bandwidth and depth of imaging, along with harmonic cancellation and *complete* lack of noise, for about the same cost. That's my two cents!
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Old 1st July 2019, 02:26 AM   #46
gabdx is offline gabdx  Canada
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grovergardner nailed it.

Thank you for telling the truth.

My experience is the same, I found good kt120 amps in PP with very exotic designs sounds way better than any solid state, low power, triodes etc, regardless of price.

They do things that the others don't, they are smooth, resolve complexity and details and control speakers in the best way possible. They are just accurate, not very sensitive to parts because of feedback.

Then there is the poison... the 845... which is a category apart.

first of all, I don't like harmonics, warm, colored sound. Well the 845 can exhibit this on many speakers, but on the best speakers, especially those big 12+ inches woofer, made from alnico etc, they show distortion and a full detailed bass that solid state amp just don't do justice too, they rumble thats all, the 845 presents the punch, the harmonics, the warm second harmonic distortion and the fine decay in bass department, but it is a colored bass.

Place the 845 with a typical 70s 80s 3 way, it will sound VERY POOR. you need some speakers to pay justice and respect to that tube, even if it is 20 watts

845 is used with almost no feedback, so it will be showing you any problems with capacitors, power supply, input tube etc, it can drive you nuts.

However, if you have the proper room, friendly 15'' woofers and proper acoustic treatment, it will give you that perfect 3D sound, full, natural, very punchy sound and dynamic.

I found that my particular amp lacked one important thing, it was micro-resolution.

So, to resume, the 845 is a picky tube, used with almost no feedback in SET, with a potential to exceed any type of amplifier, but it is not an analytical tube, it is that tube which will punch you in the chest, fool you in presenting a full opera or rock concert room with decay and proper attack, but it will not give you that fine detail of sound and will keep some warm coloration. it is the king of all drugs and obliterate any other kinds of amplification, in proper setup, regardless of the source quality. You can hook up a cheap cd player, the 845 will deliver a rich emotion full performance regardless.

To make a long post , I can add that the KT120 amp responded very well to a NOS best in the world 6sn7 gain stage, the sound just cleared up beyond imagination, it defied any measurable instruments, like a huge veil lifted from the sound... it was amazing, as soon as I put them everyone was like... wow, this is so much better. It responded very well to film power supply caps too, cleaning even more the sound..

the 845... responded well to any improvements, but it stayed that handicapped design, that crazy child, unable to drive 95% of speakers in the market because of impedance, magnet type or some kind of UFO, sound improved with a 5751 NOS (like over $100 now, i have a stock of them ), with removing cathode bypass caps (it is ridiculous how it sounds better, deifying all logics and electrical theory to remove the cathode bypass caps...), it always sounded colored, like most of the tube gears, unfortunately.
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Last edited by gabdx; 1st July 2019 at 02:41 AM.
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Old 1st July 2019, 02:35 AM   #47
multi is offline multi  Australia
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I think"Line Magnetic" are made in China
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Old 1st July 2019, 02:56 AM   #48
gabdx is offline gabdx  Canada
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if you have crazy speakers like this... only 845 will do them good. YouTube

in a 845 tube system the amp is the pivot point of the whole system, you build your speakers accordingly.
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Old 1st July 2019, 02:59 AM   #49
daqvin_carter is offline daqvin_carter  United States
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I think the 845 just wins at this game. No need to run into class A2. Plate resistance is low. On resistance is low without positive grid voltage. Looks good when lit or not.

Many are afraid of the grid voltage swing needed to drive it. You really just have to get away from thinking about a 12ax7-U7 or T7 tube for a driver. A 6sn7 can deliver 160V peak to peak as a gain stage. Use a 6bl7 if you really need more.

You can also use the 845 for lower power amplifiers and just expect really long tube life. Beats pushing a 300B towards its ratings if you need 8 watts or more.

Currently listening to an 845 amplifier that I built in 2015 and use for about two hours daily on average.
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Old 1st July 2019, 03:19 AM   #50
grovergardner is offline grovergardner  United States
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Nice post, gabdx. Regarding driving speakers, the SE 845 worked a treat on my ProAc Response 2's. I also know for a fact that they have happily driven a pair of Gallo 3.5's as well as the old Gallo towers (the ones with three or four spheres in a metal frame, I don't remember the model number). In other words, you'd be surprised what an SE 845 will drive.
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