KT66 in a Fender Super Reverb Reissue? Can it be?

[Dave W]

I think I read that a member has a Fender Super Reverb Reissue with KT66 JJ's. can it be? Any modes needed? Did you bias it yourself or have a tech do it? The reason I ask is I read somewhere you cannot put JJKT66 in fender something about the metal base being intrnally wires to pin 1 and fenders cannot handle that without a tech doing some simple mod that I am not familiar with. That may have been incorrect info though. Do you have to take thew bear claw tube holders off? As you can tell I would like to drop a set in my amp but have been a little apprehensive. Any help would be appreciated. Do they fit alright? I starrd at my amp and thought there might be just enough room to get by the transformer but have not tried it yet. Thanks!

[Spotted Dog]

...KT66's in my SRRI!

Got 'em from Bob at Eurotubes. He set me up with a full set including preamp tubes, bias probe, meter and spring clips. I'm biased to 40mA, a little above the factory setting. I biased the amp myself with Eurotube's help... they were very accommodating and full of info and prompt service, I recommend them highly.

Here is what he proposed:

So with a pair of the KT66’s you will need to change the tube retainers... [He sold me spring type that are secured at the socket then wrap around the top of the tube like a muzzle. Instructions for the procedure were included in a differnt email.]

“A matched pair of the KT66’s, a pair of tube retainers, one balanced ECC81 for V6, one standard ECC81 for V3 and four ECC83S’s to replace the 12AX7’s would run 137.50â€

[Dave W]

Thanks, its good to know it can be done. I use Eurotubes and Bob and staff are always great. Its great to hear it can be done and that it works well. I literally just put a new set of JJ's in but that does not mean I will not throw some KT66 in at some point, maybe some KT66 for Christmas in my stocking. I was wondering when I retubed with the 6L6 about it and thought it looked like there was enough spacing and thought that they would probably sound great. Maybe I will borrow the KT66 from my Vintage Modern and give it a go and try it for awhile then hets some JJ's when ready for good. Cool! Thanks again!

[Spotted Dog]

As you know, that 66 bottle is bigger than most... longer and fatter than the 6L6 glass...
2 of 'em in a sock won't leave room for much else.

They look pretty 'sick' hanging upside down inside the 'verb, all muzzled and glowin'!

[Spotted Dog]

Hey Dave W... just wanted to let you know that I just replaced the speakers with Webers, two 30 watt 10A125's with light dope on top, and two 25 watt 10F150's with no dope on the bottom per Weber's suggestion They are starting to break in and have dramatically improved the amp. Much broader spectrum of tone, the harshness of the highs at higher volumes is gone and the tone stack seems to have a much greater impact. It all sounds much richer and fuller.

Soon I want to try the set-up below using the SRRI and the VM

Hey everybody....
Heres how you do the delay thing.. 1st you need a wet and a delay amp.. Preferably two different kinds of overdrive. ex.Marshall/lFender or Marshall / Dumble.. Those are the two I use.. One side ( Marshall) put a DD-3 with all knobs set to 12 oclock, you may have to tweek them depending on the unit itself.. I have 6 DD-3s and they all sound a little different..Keeley makes a good version with a analog switch thats my current fav. Next take your Fender/ Dumble style amp use a out board reverb (ex Boss digital reverb or old fender spring) or if your amp has reverb so much the better. Disclaimer: the old Fender springs are a constant battle to keep working.. They sound great but are the crutch of my existence right now.. I carry 3, two in the trailer and one on the bus. Maybe one works right on any given day.. maybe... So delay on one side reverb on the other. This makes it all naturally separate both on stage and in the house.. Next is the most imortant thing. The Delay must be run through the effects loop.. Running a delay in front the amp is extremely difficult to handle. It runs away from you and its hard to control. The effects loop is the only answer.. Now as far as effects loops are concerned. Standard Marshall ones wired in series are the best.. Stay away from the ones wired parallel with all the knobs and controls and switches. They are way too much work and render poor results.. The rest is personal taste.. more subtle or wet or inbetween is up to you.. Its also important to realize that this is not my original recipe, its Eric Johnson's circa 1988. Got to give credit were its due. Lots of racking my brain trying to figure that one out.

Thanks Joe Bonamassa

http://www.jbonamassa.com/forum/viewtopic.php?id=1377

[Dave W]

I sold my SRR's a few weeks ago due to 6 week lapse of employment. I decided to go with VM's for now. I already miss the SRRI. I even ordered a cheap reverb pedal for Christmas as the VM reverb just cannot do things he Fender did. You wil really enjoy having both the VM and the SRRI. That will cover alot of range and be alot of fun to play. I have seen thtcombination of Weber speakers in some used SRRI's on Ebay in the past and I believe in a couple of reviews. That combination makes good sense. I have never had an amp that I plugged into Weber speakers that did not improve the sound. They make good stuff!

[Spotted Dog]

I sold my SRR's a few weeks ago due to 6 week lapse of employment. ... I already miss the SRRI.

Ouch! sorry to hear that.

Sounds like new opportunities await you, I wish you luck. :)

[MKB]

If any of you decide to install KT-66's in your Fenders, be careful to make sure the power transformer isn't getting too hot. The filament in a KT-66 draws 1.27 amps, while a 6L6GC is 0.9 amps, this means the KT-66 draws 40% more filament current than the 6L6GC. So you are potentially overloading the filament winding on the power transformer, which can cause B+ and bias voltage fluctuations, and in worst cases damage or ruin the transformer. Many amp builders think this isn't a problem, and it may not be as the newer KT-66's may draw a lower filament current, and I'm not sure what the Fender transformer is rated at (they tend to use one transformer type for different amps, meaning the filament winding may have unused capacity in a specific amp). So please be careful if you do this.

There is a way to make sure transformer overheating isn't happening, but it's a bit technically involved. You basically measure the DC resistance of the primary winding of the power transformer when it is cold, then run the amp for awhile at full output, then again measure the DC resistance of the primary while it is hot. Copper has a stable resistance change over temperature, so you can tell the temperature rise of the transformer which will tell you if it is overloaded or not. If anyone is interested I can dig up the notes on this method and post them here.

[Spotted Dog]

If any of you decide to install KT-66's in your Fenders, be careful to make sure the power transformer isn't getting too hot. The filament in a KT-66 draws 1.27 amps, while a 6L6GC is 0.9 amps, this means the KT-66 draws 40% more filament current than the 6L6GC. So you are potentially overloading the filament winding on the power transformer, which can cause B+ and bias voltage fluctuations, and in worst cases damage or ruin the transformer. Many amp builders think this isn't a problem, and it may not be as the newer KT-66's may draw a lower filament current, and I'm not sure what the Fender transformer is rated at (they tend to use one transformer type for different amps, meaning the filament winding may have unused capacity in a specific amp). So please be careful if you do this.

There is a way to make sure transformer overheating isn't happening, but it's a bit technically involved. You basically measure the DC resistance of the primary winding of the power transformer when it is cold, then run the amp for awhile at full output, then again measure the DC resistance of the primary while it is hot. Copper has a stable resistance change over temperature, so you can tell the temperature rise of the transformer which will tell you if it is overloaded or not. If anyone is interested I can dig up the notes on this method and post them here.

Thanks for taking the time to provide this valuable input. I have some more homework to do! I'm sure I can find out the filament current draw, but the measurement process is over my head.

[slowpokerhino]

WOW, this is an old thread!

Anyway, I'm probably going to be doing some mods to the amp soon (tubes and speakers) and just had a thought.
I would love to be able to run a Dr. Z Brake Lite with this amp but can't since it's 2 ohms (only works with 4-8-16 ohm loads). If I replace the speakers with 16 ohm (instead of 8 ohm) speakers that would give me a 4 ohm load. Mercury Magnetics sells a replacement transformer for the Super with a 4 ohm tap. So, I'd change the speakers & transformer and then I'd be able to run the Brake Lite BUT.. will the change in impedence effect the tone? I know the transformer & speakers will have an effect.

I guess, the short version is: if I change my amp from 2 ohms to 4 ohms will it change the tone?

-- Sun May 02, 2010 7:01 pm --

Well, today I decided to pull all the JJs from my Twin and put them in my Super.
When I went to bias it I found the 6L6s were weak. At full turn I could only get about 31 mA. That's weird. Anyway, I got a brain fart and pulled out the old "Marshall" KT66s that had come with my VM. I stuck them in (no retainer needed) and biased it to 40 mA.
Haven't had a chance to open 'er up yet (wife is home) but I'm excited to see what change it has.

BTW, biasing the Super is a bit of a PIA. I had to remove (but not disconnect) the upper left speaker to be able to get a screwdriver in the adjustment hole. Just getting to the screws holding the speaker was a bit of a chore.

[Spotted Dog]

WOW, this is an old thread!

Anyway, I'm probably going to be doing some mods to the amp soon (tubes and speakers) and just had a thought.
I would love to be able to run a Dr. Z Brake Lite with this amp but can't since it's 2 ohms (only works with 4-8-16 ohm loads). If I replace the speakers with 16 ohm (instead of 8 ohm) speakers that would give me a 4 ohm load. Mercury Magnetics sells a replacement transformer for the Super with a 4 ohm tap. So, I'd change the speakers & transformer and then I'd be able to run the Brake Lite BUT.. will the change in impedence effect the tone? I know the transformer & speakers will have an effect.

I guess, the short version is: if I change my amp from 2 ohms to 4 ohms will it change the tone?

-- Sun May 02, 2010 7:01 pm --

Well, today I decided to pull all the JJs from my Twin and put them in my Super.
When I went to bias it I found the 6L6s were weak. At full turn I could only get about 31 mA. That's weird. Anyway, I got a brain fart and pulled out the old "Marshall" KT66s that had come with my VM. I stuck them in (no retainer needed) and biased it to 40 mA.
Haven't had a chance to open 'er up yet (wife is home) but I'm excited to see what change it has.

BTW, biasing the Super is a bit of a PIA. I had to remove (but not disconnect) the upper left speaker to be able to get a screwdriver in the adjustment hole. Just getting to the screws holding the speaker was a bit of a chore.

Wow this IS old, sorry I didn't notice your updated post earlier, I've been hammered with work and time has been too short to even take a respectable dump.

Anyway, thought I'd add what I've done to my Super.

I've got JJs all the way through, KT66s at 42.5 mA, and you're right biasing was tedious. But I'll tell you what, the KTs vs the 6L6 at 32-33 mA are big full and fat, gorgeous. Lived with this set-up for a while, but even with the Jensens broken in, I still heard the brittleness in the high end at volume. Now I've got weber replacements, 2 alnico and 2 ceramics, big improvement to my ears.

Overall, this combination is damn nice, pricey but worth it IMO. More harmonics, smoother, less brittle, gorgeous cleans, more grit when needed and better response to guitar knob tweaks. The only drawback so far is the reverb is over the top with the JJ, think I'll need to go back to the GT. There seems to be less of a usable range with the JJ.

I can look up the speakers I swapped in if you like.

I love my SRRI, different cleans and grit than anything else in the stable.

[slowpokerhino]

Welcome back SD!
I know which Webers you got, I found it in another thread. Wrote it down in case I decide to go in that direction.
I'm rockin' all JJs now also. Back to 6L6s though for the time being. I got a little spooked with the KT66s but have since gotten some new info. It was recommended to me, by someone who knows much more than me, that if I want to run the KT66s I should use a solid state rectifier which will help get the voltage closer to stock (as well as tighten up the bass a bit). Haven't ordered it yet but Tube Depot has them for $10.
I'd also recommend trying a few "tricks" I've learned. Remove V1 if you don't use the normal channel. Replace the 12Ay7 in the PI position with a 12Ax7 (like the one you just pulled from V1). Both of these have a noticeable effect on the amount of gain you get and if you don't like them, just put them back.
I'm still contemplating the transformer/speaker change as described above only now I'm also thinking of converting it to a 2x12. Would probably lose a little punch but the bass would probably hold together a bit better and getting to the bias adjustment would be cake.
And I agree completely about the reverb with the JJ. 2 is not enough and 2.5 is too much. Very sensitive. Let me know if you find something that works better.

Sorry to be so long winded (so to speak) but I don't know anyone else with a Super.

Rectifier:
http://www.tubedepot.com/tdssr.html

Like this:


Derek Trucks settings (for the hell of it):

[Spotted Dog]

Just went back and read the whole thread; MKB is right, the amp does run pretty warm, so I think I'll try the SS recto. Definitely need to try the V1 trick and the 'x7 in PI, hmmm like that too, guess I have a project today.

2x12, what would you put in there?

Always wondered what DT's settings were, I would never have guessed the treble and bass settings, but the volume makes sense heh heh. I guess he has an interesting tube and speaker mix, including Pyle or Pyle clones from weber. But I think the key to his tone is the torn grill cloth and the little figurine sitting on the amp.

BTW, did you here G Allman just had a liver transplant for Hep C, so DT and wife are subbing in at the Crossroads Festival.

[slowpokerhino]

Not sure what speakers yet. Maybe Weber 12F150s, Tone Tubbys or G12H30s or I might even pull the vintage Jensens from my Twin.
The hard part is that it all pretty much has to be done in one shot (transformer, speakers, speaker baffle) and that's quite a bit of money to come up with all at once right now.

I was surprised by his settings also. I tried them and it was way too bright. But then I still have the stock speakers which make everything too bright and I don't play with my fingers. I can definitely see why he never uses his bridge pickup alone now.

Yea, I just heard about Gregg yesterday. It's a shame they'll miss Crossroads but it's cool Derek & Susan will still be there. I'm praying for his speedy recovery. BTW, I got "Roadsongs" yesterday and it is a definite must have.