Quartet of KT88's + Renegade = Epic

Got a quartet of Ruby KT88's, pre burned in and matched up.

Sorry for the hueg pictures. I thought I resized them enough... oh well.

Had to do some modifications to get them to fit. the flat metal clamps are too narrow to accommodate the larger base of the 88's so they had to come out. Also, since this is my gigging amp, something's gotta hold them in so I ordered a set of kt88 retainers from the tube store. couple of bucks each.

Anyways, here's what all is needed for the other renegade owners that want to try this.

-Drill/screwdriver w/phillips head. If you use a drill use a socket extender
-Jeweler's (or tiny bit) phillips head and flat head screwdrivers.
- Multimeter
- Wire cutters (not sure if you need these for the head version)
- KT88's


I started by unplugging the speakers from the amp and snipping the zip tie holding the wires together for the internal fan and unplug the connector.

Next, I flipped the amp on its face and removed all the screws on the back panel and removed the panel.




there are 4 large screws holding the amp into the combo that I removed. they're deep past the PCB so the socket extender is needed to get to them.





Once the amp is out, I flipped it right side up laying it on top of the back panel that came off.




Out comes the retainers. Tiny screws.




Retainers go in



Tubes are in! (pinch the top of the retainers so when they slip over the tubes they're snug. Time to bias these bitches up.




BEFORE YOU TURN THE AMP ON SET THE BIAS ALL THE WAY COUNTER CLOCK WISE!! Also, bruce recommends turning all the volume knobs all the way down.

the EL34/6L6 bias setting is WAY too hot as it is and turning it on will pump way too much juice to them so backing the bias all the way down will let you safely raise it up.

Use a small jewelers screwdriver to turn each bias knob. As you can see the bias is nice and low.






Your aim is to turn each bias knob till it reaches between 70 and 80v. 75 was my target.

BE CAREFUL WITH TURNING IT!! the knob is EXTREMELY sensitive. you probably will only end up turning it maybe a quarter of a turn at the most. make tiny adjustments, let it settle a few seconds and then adjust as needed.

like this




When you get the other side biased up, and it's settled, go check the other side. Chances are, it's drifted a bit so adjust it as needed. Once both sides are in their bias range, plug in and tear it up!


As bruce and Jeff have noted, with the tube blend knob in the center, the wattage output is at a maximum so that's where the knob is set. What I've noticed is an immediate increase in overall heft of the sound. It's got (as i assumed) a slightly more percussive attack to the sound and when I really cranked the thing, it has a slightly cleaner overall sound. Most notably when the gain is cranked.

Anyways, it wasn't a particularly cheap mod but when trying to extract the absolute maximum amount of clarity when playing at stupid stage volume, they made a noticeable difference without any loss of character or any tone or voice change. The clean headroom the clean channel has is absolutely astonishing... far beyond any volume I'd ever use on stage to put it in perspective.

Great post.

Do you have to do that EVERY TIME you want to swap tubes - remove the chassis?

Looks cool man,did you have to drill extra holes for the tube retainers?

Didn't have to re-drill any holes. The KT88 retainer mounting brackets have holes that the screws screw through to hold down.

Nick, no need to remove the chassis for tube swaps. I removed it to make mounting those tube retainers MUCH easier. The black panel on the front of the combo with the egnater logo on it is velcro'd on there and when removed, gives clear access to all the tubes.

The guys at harmony central are clamoring for some audio so I'll try and get a video done after work if not, tomorrow.


Edit: Jason, I noticed in your sig you dig the MC pickups. I've got Wade building me an AFWAYU and Detroiter for my JP6. It's been about a month so I'm getting pumped!

AFWAYU's are sick pickups man.

The EBMM Petrucci isn't the beefiest sounding guitar, acoustically. And the Afwayu's are crazy obese beefy. They'll be just the ticket to fatten that thing up.

FastRedPonyCar":zpxswlya said:

Didn't have to re-drill any holes. The KT88 retainer mounting brackets have holes that the screws screw through to hold down.

Nick, no need to remove the chassis for tube swaps. I removed it to make mounting those tube retainers MUCH easier. The black panel on the front of the combo with the egnater logo on it is velcro'd on there and when removed, gives clear access to all the tubes.

The guys at harmony central are clamoring for some audio so I'll try and get a video done after work if not, tomorrow.


Edit: Jason, I noticed in your sig you dig the MC pickups. I've got Wade building me an AFWAYU and Detroiter for my JP6. It's been about a month so I'm getting pumped!

Click to expand...

I noticed 4 holes but it was early and no coffee yet I have a real picky LP,and bright so I dropped the Afwayu's in and end of story,I almost sold the guitar but now,it's my fav,the detroiters are super killer man,I put them in my Anderson,Sorry about rambling and going OT,now back to your regular programming

Awesome post man, very informative!! I am about to swap the tubes out in my Renegade head and never having biased anything I was a little hesitant. Just seeing some pictures though really helped, it seems pretty easy. Just to be clear, once you install the new power tubes are you saying you should ALWAYS turn the bias screws all the way counterclockwise before you power the amp back up and then work your way up slowly to your goal (i.e. 75mV)?

Question about re-tubing a Renegade head. I know you have the combo but does anyone know if you have to remove the chassis from the head to change the tubes? I'm pretty confident that you do and that this is a pretty stupid question but I thought I'd ask it anyway just to be sure. Thanks

no you shouldn't have to remove the chassis.

If you're swapping the same type tubes, you shouldn't have to pre-sweep the bias adjuster. The only reason I say do that is because the bias setting for the EL34 and 6L6's will be well up in the 90's V if you turn the amp on so lowering it down will let you raise it up to the proper level.

I put a pair of KT88s in my Renegade head. I didn't bother with retainers, the sockets seem tight enough. Had to remove the original clamps also. the OP is right about the bias though. I didn't turn the bias pot all the way down and when I checked the bias it was around 110! Fortunately I already had a screwdriver on the pot and quickly turned it down. My 88s have tube rattle so I had to add a couple of tube rings to each to quiet them down. They sound great with a pair of Siemens RFT 34s.

Nice playing Drew, great tones too!!!

Drew,

You mentioned you have the amp attenuated at 15db. What are you using to attenuate the amp? Also, what style do you mostly play. I am a classic rock guy, do you think this would be a good choice? If so, this is going on my list of things to try.

Your demo is fantastic

TJ

I must have had a hot plate between the speakers and the amp to bring the volume down.

Amp thrives in the classic rock, fusion, blues type music. Buy the head/cab though. The combo weighs a TOOOON.

Drew, Thanks for the response. I already have the combo.. lol I got a good deal on it in perfect condition it was $700.

TJ