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In Reply to: JJ EL84 suck in Crate guitar amp posted by yoyo on August 19, 2002 at 04:26:02:
Hi,No idea what a Crate VC50 may look like but it sounds like the JJs are leting more current through. A bit more bias may do them good.
Follow Ups:
They sound more like dying tubes.
But I won't be going in to adjust the self bias curcuit.
The sovtecks are quite good sounding. I was just looking for a little more prescence and clarity, but I think I can still add more of this in the pre section. Funny enough the reviews of the sovtecks are generally neutral to positive just nothing stands out as spectacular. Which must mean they are a pretty good tube. Which in my experience I would say the creamy midrange is quite worth any slight loss of clarity in a guiar amp. you can turn this one up reall loud and shake the walls before your ears start bleeding from pearcing trebles or a monotone midrange.
More of a small warning for any arcive searchears.
Hey arcive searches, in my guitar amp the JJs compared to the sovtecks sounded edgy, lacking base and missed the smooth creamy mids.
For me its either NOS or sovtecks. I will keep the sovtecks and save the glitter and gold for the pre section.
I also think there may be an issue of microphonics here aswell with the JJs in this combo setup.
Haven't heard the JJ's, so take this for what it's worth, but you may want to try the Ei's. Sound darn near as good as Amperexes in my amps. Cheap, and rugged to boot.
Bill
Yoyo,These amps bias the EL84 very hot. I wouldn't put anything but tough Sovtek EL84 (EL84M or 6pi14-EB, the military version close to the 7189A) or Tungsrams EL84 tubes into this amp.
Any US made NOS 7189A would be a good choice. I've used NOS Amperex BB, Mullards, MOV Gold Lion N709, and TFK EL84's. All work well in gutiar amps which really push plate voltage and bias in this type of tube. EXCEPT, the TFK---this tube has always sounded a bit anemic to me.
But, for the price the 6pi14-EB is the tube you should get. It is tough, can take a lot of abuse, and makes good tone---better than the Sovtek EL84M, in my opinion. The Russians make much better EL84 type tubes than the Eastern Europeans, for guitar amp use.
You can get the 6pi14-EB from Kevin Deal at Upscale Audio. Other US made 7189A can be bought from eBay or Tube World---amongst other places.
The Tungsram EL84 is another tone monster. It can take voltage and make a healthy tone. It won't last as long as that 6pi14-EB---but does have this wild compressed tone.
The best EL84 in terms of tone, in my experience, is the MOV Gold Lion N709---in a Class "A" amp---like Matchless or old Voxes. But, they are unfortunately, near extinction.
I like the Mullards over the muy expensive Amperex Bugle Boys. In fact, I like the old Sylvania 6BQ5 (yellow lightning logo) over the Amperex. And a good RCA or GE 7189A really puts out good tone and has the ruggedness you need in your guitar amp.
I haven't had much luck with either the JJ or the Ei EL84 in combo amp application. They just don't last too long---and lack the huevos of a good Sovtek, Tungsram, or most 7189A's.
I think after more study and being burned once is enough for this round, I will get some new standard sovtecks. and try any cheap 7189 that come on ebay.
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