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EQUIPMENT FORUMS >> TORII MK IV >> Experience using 807 tube
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Message started by safebelayer on 03/13/23 at 00:14:17

Title: Experience using 807 tube
Post by safebelayer on 03/13/23 at 00:14:17

I just installed some RCA 807s in my mkiv. All but one tube transmits sound to my speakers when I tap on them. I have not had this experience with 6L6, 7581a, EL34, or 6p3s tubes.

Does anyone have any experience with this tube in their mkiv?

Thank you

Title: Re: Experience using 807 tube
Post by jec3504 on 03/13/23 at 03:14:36

safebelayer,

From your description sounds like the tubes went microphonic.

Title: Re: Experience using 807 tube
Post by Rivieraranch on 03/13/23 at 05:14:14

When I had my MK4 I ran 807 tubes in it. On each side I had one Soviet and one Canadian Westinghouse. I didn’t worry about whether the tubes were microphonic or not; most tubes are anyway, if you hit them hard enough you’re going to hear something. And I don’t like the RCA‘s. Aesthetically, they lack the metal girdle that shields the wires coming down from the plate. And their sound is very bright, forward. I like the other brands much better. They are more tubey sounding, with a nice old radio intonation. National Union, Raytheon, GE, Tung Sol. I hope I haven’t left anybody out. I am using Raytheon‘s right now in my mini.

Title: Re: Experience using 807 tube
Post by safebelayer on 03/13/23 at 05:34:04

Thanks for the suggestions. I wasn't tapping the tubes hard at all. I'll try some 5933 tubes tomorrow.

Title: Re: Experience using 807 tube
Post by Rivieraranch on 03/14/23 at 01:44:43

I’ll bet those 5933s are JAN Sylvania. I did an A/B comparison and the 5933s had no bass.


Title: Re: Experience using 807 tube
Post by safebelayer on 03/14/23 at 03:37:29

I'm having a different experience with the 5933wa tubes. The tone is beautiful. The bass doesn't slam, but it's definitely present. One of the most realistic sound producing tubes I've tried. Here's a list of my past tubes:

EL34: Svetlana reissues 👎, nos SED winged c 👍, NOS Mullard xf2 👍

6L6 types: nos Svetlana winged c 👍👍, tung sol reissue ok, 6p3s good, 6p3s-e 👍+, tung sol 7581a 👍

807: RCA 👍  if not microphonic, Sylvania 5933wa 👍+

Kt77: gold lion reissue 👍

Kt66: gold lion reissue ok

6ca7: NOS Raytheon ok+

If anyone has questions on a specific tube type, please pm me. Too much to write here to give reviews on each.

Title: Re: Experience using 807 tube
Post by safebelayer on 03/14/23 at 03:39:20

By the way, it appears the microphony was caused by the tubes not the adapters.

Title: Re: Experience using 807 tube
Post by Rivieraranch on 03/15/23 at 00:08:06

I’m not surprised that those RCAs are microphonic. If they are the last gasp 1970s or 1980s production, no wonder. The RCA is have all those naked wires running from the plate down to the bottom of the tube whereas the other manufacturers put that metal girdle around the wires as they exit below the plate. I don’t know if that is more than aesthetics at work. I acquired a group of 1970s RCA 807 tubes And they tested extremely high for trans conductance, 6000 to put that in perspective the older national union and other tubes tested around 3800 to 4400. Mind you this is the 6L6 test data which calls for 5000 as a normal tube. So the high trans conductance explains the lively presentation

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