JJ KT88's and Integrated quads

Necrovore · Post by **Necrovore** » Tue Oct 11, 2005 1:12 am

Wondering if anyone has tried the JJ KT88's in a SL or KT88's for that matter. Also what is anyones take on Eurotubes Integrated quads. He sells sets of 6L6 pairs and EL34L pairs that can be biased together and run as a quad.

Billy Batz · Post by **Billy Batz** » Tue Oct 11, 2005 7:27 am

YOu have to watch the heater current draw with KT88s. Check the ratings of the brand you buy and make sure it doesnt exceed the PT you have.

Eoin · Post by **Eoin** » Tue Oct 11, 2005 9:18 am

Any fundamental changes to the bias or anything else required for KT88s?

Guest · Post by **Guest** » Tue Oct 11, 2005 9:29 am

Billy Batz wrote:YOu have to watch the heater current draw with KT88s. Check the ratings of the brand you buy and make sure it doesnt exceed the PT you have.

Ok I understand what you are saying, but are the JJ KT88's actual real KT88's or just beefed up 6550's sort of like how they have their EL34 and EL34L.

I do not think I would ever try real KT88's in a stock SL, For one I think like you said the Transformer might not be able to handle it, and two real KT88's as a set would probably be worth more then the amp itself. I'm not willing to shell out $1700 for a NOS quad of GEC KT88s.

Billy Batz · Post by **Billy Batz** » Tue Oct 11, 2005 9:56 am

I wasnt even trying to talk about the specs of brands of tubes. Im not that familiar with JJKT88s. Just making sure you know to make sure. There are current production tubes that draw a lot more heater current then EL34s. Seems like you know more then I do about them.

Necrovore · Post by **Necrovore** » Tue Oct 11, 2005 1:25 pm

Ok, thanks. Didn't want to run off headlong into this and get stuck somewhere along the way. I will ask Bob over at Eurotube for the specs and see if I can even run them in my amp.

Country Boy Shane · Post by **Country Boy Shane** » Wed Oct 12, 2005 2:23 pm

Be sure to update us on the status of how they sound in your amp. I'm really curious too!!

Necrovore · Post by **Necrovore** » Wed Oct 12, 2005 8:00 pm

Ok Bob emailed me the spec sheet for the JJ KT88's if anyone wants it just pm me your email address and I will send it off.

I asked him specifically what your concern was Dan. Apparently the JJ KT88's are drop in replacements for 6550's and the Stock Marshall transformers from the 800 series back can run them no problems. I think I will have to change out the resistor that goes to the bias pot though to a higher value to get enough negative voltage to bias them correctly though.

xjeff79x · Post by **xjeff79x** » Thu Oct 13, 2005 3:02 am

KT88's use 1.6 amps per tube. 6l6's use 0.9 amps per tube. 12AX7's use 0.3 amps per tube. The 100 watt power tranny is rated for 7amps output for tubes, right? So using integrated quads, the 6l6/kt88 setup will only draw 5.9 amps off the power tranny that is rated for 7. Well in the safe range. Speaking as a Marshall using EL34's draws a total of 6.9 amps, you are safer running those integrated quads. Just make sure the bias is right.

Jeff

Metropoulos Forum

JJ KT88's and Integrated quads

JJ KT88's and Integrated quads

Integrated Quads