Electro Harmonix 6550's ordered

[shreder75]

...vrad is chomping at the bit to turn my two input Quick Rod into a pro mod so I finally ordered the 6550s today..went with those over the KT88s because those are what Rich Ward uses and his tone crushes for the heavy stuff...

if there's a brown out in the power grid on the north eastern seaboard in a couple weeks' time you'll know that things went horribly awry...

as a side note, i finally decided on an f spaced norton to replace the JB in my lynch..and not one decent well known musical outlet has them in fucking stock!!! grrrrrrrrrrrrrrrrrrrrr

as you were

 

[harddriver]

It's really a matter of taste I love my 6550's in my splawn modded JMP. I usally compare 6550's as a bigger 6L6. I could never bond with a true EL-34, the low end always seemed to loose for me, dunno! It's either 6550's or true 6CA7's(which are pretty much a 6l6 operating a El34 voltages) for me. I did buy some JJ 6ca7's for my super bass build which hopefully I will finish by the end of this year which seem like a good compromise for me tone wise.

KT-88's on the other hand sound like a bigger rounder EL34 with more womp in Splawn. Stay away from the JJKT88 the low end is extremely compressed sounding form my experience. Suprisingly the Sovtek KT88 sound great and are cheap pricewise. Both the Eletcro Harmonix 6550 and KT88 are pretty decent tubes and sound good in a Splawn.

One thing you may want to discuss with Vrad is the PI grid leak resistors in your amp are 220K for EL-34's, I know scott still uses 220K's with KT88's but the 6550's will pull more grid current than even the KT88. You may want to lower them to 150K or even 82K as Marshall did. You may notice a reduction in low end with .022 in the PI but with the lowend of a splawn it probably won't be enough to notice with 150K's. On a side note I still run 220K's in my splawn with 6550's biased cold around 50% max which also helps with excessive current draw and possible runaway bias while using 220K grid leak resistors&6550's), don't bias the 6550 tubes too hot otherwise they get tubby sounding and lose there nice tightness IMHO. That's about all I have, let me know what you think, the amp will sound different, with more lowend less emapsized mids with more top end.

 

[shreder75]

well I asked him about biasing and the 88s vs 6550s and whatnot and nothing was ever mentioned about the grid leak resistors (sounds like some kind of cybernetic implant..lol)...

 

[shreder75]

however, he DID mention biasing the 6550s lower than that of the 88s...so it sounds like what he told me is similar to what you're doing with your 6550 loaded splawn mod

 

[harddriver]

My point being that you can get away with using the 220K grid leak resistors that are already in your splawn if you bias the 6550's no more than 50% of dissipation and maybe colder, the 6550's tend to like colder bias ranges with my experiences with them tonewise. If you have any concerns you can swap the 220K out to 150K's for peace of mind. You may need to swap resistors out on your bias supply if you don't have enough bias range in the amp, but I think Scott uses a very large bias pot with alot of adjustability so you may be fine just turn your bias way down when initially firing the amp up then adjust it up to your setpoint.

I had Sovtek KT88 in my Splawn JMP when I got it back form Scott way back in 2003, and have been running my Winged C 6550 ever since with no issues. The KT88's are a little warmer sounding but I love my 6550's.

 

[shreder75]

thanks for the info, HD..appreciated...talked to scott, issues solved and we're all good to go...still watch out for that brown out on the news though..hehe