Got some 7868EH's for the 400.....

[larryderouin]

FINALLY. As much as i run the 400 anymore (80+hours a week) it was starting to take more and more gain on the volume control to get the kind of SPL I wanted, and the sound was kinda flat and lifeless, no depth, just Solid State!!!:thumbsdn:

Ordered a set of 7868's(EH's) from McShane on Monday. Came this morning with the mail.

Pulled the 400 out of the Coronet console, did an off going voltage check of the BIAS Circuit. (-19.20V) with the tubes pulling btwn 22-24ma each. Pins 1-7 was 370 and Pin 9 400.

Crammed in the new tubes after dripping De-Oxit on a pipe cleaner and running it in the sockets. I didn't think they'd go in, or they'd break before I got them in. MAN ARE THEY TIGHT!!! Think 13 year old virg....Forget it, there's no such thing anymore.

Powered on with meter attached. Everything came up nicely. Line voltage at wall 124, but with a -12V bucking transformer, I'm running 112 with 5.9V @ V7-8-9-10 heaters. After 30 minutes the tubes checked as follows: BIAS VOLTAGE IN -19.15V; PINS1-7 369V, Pin 9 399V. ma@ 10oHm resistor. V-13 24.35ma., V-14 27.21ma, V15 24.79ma, V16 25.43ma. This was with source set to AUX, and 50Wdummy loads onboard, volume @ ZERO. I haven't built or installed Drew's BIAS Mods yet, but it's definately on the list (going to top of list now). Tubes heated up evenly, no hotspots or redplating.

Put it back in the Cabinet after 1 hour test phase. Connected everything and powered up. OH MY GAWD!!!! Separation widened to across the room, there is a depth of field that wasn't there before (you can sense one section of orchestra behind another etc. feel like I'm back in High School Orchestra again.), I can hear finger plucking on strings now, sticks tapping on drum rims, or heads now, then the sound of the head or rim struck. Listeing to some Benny Goodman and can hear the clarinet keys clacking.....TOO FREAKIN MUCH!!! WOW!!!!!!!!

I've been listening to it for going on 7hours straight now. It's just getting better. The volume used to be set for 9:30-10:00 before and it was comfortable and sounded good. Now it's set like 08:00-08:30. All that from a set of NEW Output tubes. Between these and the 7591's in my Sansui 1000A, it's gonna be hard to listen to just one. (Flip a Coin???) Easier to eat only one LAY's.

The old ones are going in long term storage (backup's)

Larry

 

[DonQuixote99]

Nothing better than a big step up for the system.... :yes:

Now does that designation with the EH on the end indicate the manufacturer source for the tubes? And is the brand the same for the old tired tubers?

 

[larryderouin]

EH is just the Designation for Electro-Harmonix. If you get some, the pins are slightly larger than the old stock tubes. So if you go back to old stock, you'd have to reset the sockets.

EDIT: Of the old tubes, 3 were FISHER Branded, and the 4th a Raytheon Branded. Can't remember if they were made by Westinghouse or Sylvania.

Larry

 

[audiodon]

EH 7868s are great tubes and worth more than the price. Glad this worked for you Larry. That's a lot of weekly usage.

 

[larryderouin]

Funny thing is the one's it came with still show in the 60%-70% range on my tester. They were just starting to sound tired.

 

[tubeboob]

Ahhhh . . . The Fisher 400 . . .

Ah, The Fisher 400, I know what you mean, I have two of them, and also 2 X202B's.

I simply love my Fisher pieces.

One 400 is in daily use, has all original output tubes and preamp tubes.

I excellent original condition, except for the new brass knob covers.

Pushing the sound with a Sony 707ESD CD player, and using a pair of Cizek Model Ones.

I just close my eyes and drift away . . .

Like a a lot of fine things vintage, they only get better with age.

BTW, how about some pics??

Cheers

 

[larryderouin]

Pics are in the Coronet 808 II thread down a bit. This is the one I put in the console a few weeks ago.

It's been running NON STOP since I put the tubes in y'day. It's actually opened up a bit, the mids are a smidge more in front and separation has narrowed a little to about 2/4 of the room. but the depth of field hasn't changed other than it's somewhat more defined.

Ill shut her down tonight and pick up tomorrow when I get up, and see what a coold down cycle does. Nothing like a TORTURE TEST!

Larry