JAN Sylvania 7308 vs. JAN Sylvania 6922

[Rodango]

Test Lashup
=========
Njoe Tjoeb 4000 CD player with USN 7308s
Ming-Da MC67-HA Preamp

Chinese TM300
Three 6DJ8s in the preamp
Four KT88s (New issue Gold Lions)

6DJ8 set #1
JAN Phillips 7308 phase splitter
JAN Sylvania 7303 amplifiers

6DJ8 set #2
JAN Sylvania 6922s -all three

Both sets, '78 - '79 vintage

Test track - 2002 "Falling through time"

I started the shootout believing the 7303s would win. I rolled the sets back and forth and listened intently. At first, I heard absolutely no difference so I rolled and compared some more. Finally I heard it. The 7308s were great on the high-end but were a little shy on the mids whereas the 6922s smooth and eloquent across the entire range.

Who would have thought the 6922s would have won my shootout? Not me. Perhaps I should take the Phillips out of the 7308 lineup and replace it with a Sylvania. Phillips tend to be a bit 'tizzy' but I really like Sylvanias

The only difference I could find 'in the book' between 7308s and 6922s was that 7308s have a TINY bit more heater current.

Has anyone has similar 7308/6922 comparisons? Does anyone know why both these tubes were manufactured if they're so almost identical?

Thanks!

[refference]

Hi Rodango ,

The 6922 was the normal commercial tube , and was sold
and used anywhere . They was the “ standard “ tube , made
by Sylvania and many other manufacturers .

BUT the 7308 , was a Sylvania Gold Brand , PREMIUM
TUBE version of the common 6922 , and was designed and
manufactured for CRITICAL industrial and commercial
applications. The 7308 is the BEST , everything what any
6922 would like to be .

I agree with you , always that is possible , I prefer the Sylvania
branded tubes .

Regards ,

Carlos

[the_manta]

hi !
Way back I did some similiar tests. At that time I didn't had ECC88. I used following:



Maybe my test were not as enthusiastic as yours , but I couldn't hear any difference. Would be a good reason to sell this siemens CCa and E88CC junk.

Regards, Simon

[SY]

I've tested a wide range of ECC88 types. Of them all, the CCa showed the best linearity. So don't be too quick to throw them out.

[Positron]

The E88s are harder to design around because of their higher frequency capabilities. Alot of people don't know how to design around this tube and trash it.

[zigzagflux]

Originally posted by Positron
Alot of people don't know how to design around this tube and trash it.

That would be me.
Blasted tube.

Had 5MHz oscillation; never found the problem. Could have been heater borne RF (my best guess).

I'm sure it's a good tube if used with extra special precautions.

[pocketchange]

Yep,

Tuff to beat.

Then again a pair of Amperex/Holland 7308 PQ's w/2 Stars (circa 1961) maybe the ticket,
if you've deep pockets.

pc

[Bob, W7ETA]

If I remember correctly, the PCC88, ECC88, and E88CC all have the same curves, but different heaters. I haven't seen any information indicating the plates and grids are the same for each of those tubes, just the curves.

The E188CC and E288CC have different plates and different curves than the CC88 and 88CCs.

I believe the internal resistance is the same for the CC88 and 88CCs but is different in the 188 and 288s

The rumor I head was that the E88CC has dual winding for the heater--if one winding broke, the tube keeps functioning--very helpful for military and commercial applications.

Best Wishes
Bob