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I shall be lanced for this...

70.177.113.236
Posted on November 2, 2009 at 16:36:00
SteveBrown
Audiophile

Posts: 1523
Location: Tulsa!
Joined: November 14, 2002
 Okay, I'm an experimenter in the most loose sense. As I posted a week or two ago, I've been playing again with some OLD 300B SE designs. I got to wondering about a pair of 801's I have here. Okay the Rp is HIGH and the filiment V is also HIGH. But with a couple mods I stuck them into my "Flesh and Blood" 300b chassis. You know what? They sound wonderful. I can get about 6vdc on the fils without major mods, and I can change my OPT tap to 5k input, 4ohm output (8ohm speakers). The bass is so much better than I anticipated. But that's not the good thing. The overall tone is really nice. No not nice, great! There is some kind of rightness to the tone I have not heard before. There is openess and air in the top, in the mids wooden instruments are just wonderful. Anyone else play with these triodes?

RE: I shall be lanced for this..., posted on November 5, 2009 at 16:27:01
gluca
Audiophile

Posts: 749
Location: SomeWhere Islands
Joined: February 17, 2005
 my preferred tube, well my 2nd preferred tube ... 75TL comes first.

No lance..., posted on November 2, 2009 at 17:09:12
Jim Dowdy
Manufacturer

Posts: 1168
Location: western North Carolina
Joined: July 22, 2000
 I'm an advocate of all-DHT designs...in fact, I recommend that you consider the high-mu cousin of the 801, the 841.

Do you prefer 3C24 or 841 as driver?, posted on November 5, 2009 at 17:22:18
nc
Audiophile

Posts: 315
Location: San Francisco, CA
Joined: November 19, 2003
 Just wondering, assuming both are loaded by exo-99 on the plates.

Re: Do you prefer 3C24 or 841 as driver?, posted on November 5, 2009 at 18:10:15
Jim Dowdy
Manufacturer

Posts: 1168
Location: western North Carolina
Joined: July 22, 2000
 It is difficult to provide an easy one-size-fits-all answer. Do you prefer chocolate, vanilla or strawberry? If you prefer strawberry today, are you allowed to prefer vanilla tomorrow...or chocolate next week?

In all seriousness, I am not trying to be silly or to provide enigmatic distractions - tastes, situations, needs, and systems change and evolve. The setup du jour might not be the preferred approach next week.

There are times that the higher mu of the 841 will be critically important. One must also bear in mind that the 3C24 is considerably more difficult to employ due to its filament current (3.0 A vs only 1.25 A for the 841)...and its exposed plate cap also presents another potential complication.

I could make the case that the ultimate front-end tube is the 75TH; but do you want to deal with its rarity, its 12.5 A of (stereo) filament current, and/or its exposed plate caps? And after all that, is its mu of 20 adequate?

Having said all of the above, I find something uniquely magical about the cylindrical-plate Eimacs. But the 841 is probably the more practical all-around choice for most people.

801A, posted on November 5, 2009 at 07:32:26
Dave-A
Audiophile

Posts: 9405
Joined: May 30, 2000
 I have listened to this tube in linestage and driver applications with a variety of OP tubes, like the supercharged KR and Vaic 300B types. You have too, at my place. IIRC. But who's keeping track?

This tube has a beautiful robust sound with huge imaging and that lush 10 sound. Like a 10 on steroids.

One of my all time faves. The 801 is getting harder to find, whereas the 841 not so much, but I don't have much experience with the sound of that one...just one amp Sam built.

Later
D

Re: 801A, posted on November 5, 2009 at 13:05:45
Jim Dowdy
Manufacturer

Posts: 1168
Location: western North Carolina
Joined: July 22, 2000
 I have indeed heard the 801A on a number occasions - as Dave says, it sounds like a muscular 10/10Y.
However, I have not personally experimented/built with the 801A.

How about the original RCA 801, white based, carbon plate..., posted on November 5, 2009 at 14:23:54
Interstage Tranny
Audiophile

Posts: 1403
Location: Eastern
Joined: October 4, 2006
 The original 801 is really robust, able to handle high plate voltage and current. Plus, it works into any load opt without fuss. Power is easily increased with this bad boy.

841 is a VT-51, rare indeed, but not in high demand. They require less bias but high drive. GL versions are out there, but not easily found in pairs. I still vote for the original GL10, or 801 with porcelain base, for best sonics.

can you explain that please?, posted on November 9, 2009 at 14:45:22
gordan
Audiophile

Posts: 419
Location: Belgrade SCG
Joined: July 9, 2005
 "Plus, it works into any load opt without fuss"

any load opt? do you mean impedance or something else here?

Yes, I can explain that, I think..., posted on November 9, 2009 at 16:00:52
Interstage Tranny
Audiophile

Posts: 1403
Location: Eastern
Joined: October 4, 2006
 Yes, the reflected impedance or load impedance of the 10 family of tubes is usually very high. The carbon graphite plate, ceramic base version 801 is unperturbed by lower impedances. So, while an 801A wants to see a 7-10K Ohm load, the original 801 doesn't mind a 3K Ohm load. The 801 can do well with the high load, as well.

What is most important about these original 801s is how forgiving they are of high plate voltage and current. They really can put out some power, driven correctly. Check out their plate structure compared to the postage stamp size of the later 801A/VT-62. 801s are worth finding and trying...

RE: Yes, I can explain that, I think..., posted on November 11, 2009 at 07:13:35
PakProtector
Audiophile

Posts: 9949
Joined: May 14, 2002
 The reaction I keep having goes something like, 'how do you arrive at these conclusions'. I've not seen any indication that the gm/R_p varies much across the 801 family. It is likely that actual plate dissipation values might, but that does not much towards working into lower loads comfortably. In that arena it seems to be mostly a f'n of R_p...now that varies considerably across the output voltage swing....
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
Empirical Evidence, My Friend..., posted on November 11, 2009 at 18:13:49
Interstage Tranny
Audiophile

Posts: 1403
Location: Eastern
Joined: October 4, 2006
 Have you tried these tubes in SE ? How about push-pull ? When you do or have, comparing the various types of 10 tubes, in circuit, will definitely convince you that these original 801s are most forgiving. Also, please check the circa 1937 Transmitting Tube Manual. There, you will see the published data for the original 801, which might be a bit different than the 10 family specs.

Come to think of it, have you seen any 10 family specs for AB2 operation ? I would like to compare. Nevertheless, specs aside, 10s, VT-62s and 801As do not like low Rp. Ceramic based 801s, with chunky, carbon graphite plates, don't seem to mind them, at all...

RE: How about the original RCA 801, white based, carbon plate..., posted on November 5, 2009 at 18:32:25
wdh.co
Audiophile

Posts: 72
Location: NE England
Joined: January 4, 2003
 Like these
Iam now using graphite 801 for drivers and outputs the bass and mids are better than the 801a if you can believe that.

Photobucket
Sweet ! ...(nt), posted on November 6, 2009 at 08:04:52
drummerwill
Audiophile

Posts: 292
Location: St Louis Mo.
Joined: January 7, 2003

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