I use a "preferred series" 7025 from thetubestore.com. Don't know who manufactured it, but it looks very similiar to the Sovtek 7025's that i have.

For any of you guys who want to run 6L6WGB's or 6V6's in your Overtone, but have been a little scared to, I have figure out a way to do so. I love the little 6L6WGB tubes due to their tightened bass response, and great all round mid and treble response, and find myself switching back to them often, especially since i now have the HRM post OD tonestack disconnected.

In order to use these tubes without modifying the Bias circuit is to knock down the Plate/B+ voltage. The reason for this is that in stock form, the bias adjustment circuit cannot adjust the current low enough to get a stable current load at a safe 70% dissipation rate. At Full Plate Voltage ( 447 volts on mine measure across Pins 3 & 8 ) the recommended 70% dissipation current rate is 40.7 mA. At full voltage with the stock bias adjustment circuit, it will only get down to about 42 ma, which is only about 2 mA above the 70% dissipation rating. i have run them at 50 mA with no redplating, but it is hard to get a clean sound at that high a current going through it, and they certainly won't last long like that, either. Many tube reviewers will say that these little tubes sound great at 50 mA (myself included), but again they won't last long.  Another problem is current creep. At high voltage, those little tubes tend to creep up at idle, so they won't stay where you want them.

To knock down the plate voltage, i use the Sag simulator resistor that Nik installed for me. It puts a 150 ohm cement block type resistor on the center tap of the HT taps. This drops the plate voltage down 20 volts, down to 427 volts on my amp. At this voltage rating, the current flow to achieve a 70% dissipation is 42.6 mA. This is easily achievable through the stock bias adjustment circuit, and it remains stable at this voltage as well.

All the 70% current rating numbers were figure through Weber's Boas calculator app @ http://www.webervst.com/tubes1/calcbias.htm

The addition of the Sag resistor switch is an easy one, and if any one has thought of using 6L6WGB's or even 6V6's in your Overtone, but have been a little gun shy, this might be the mod you have been looking for. Also, if you want to drop the voltage down even more to use older 6V6 types, you could add a large resistor value to knock the B+/Plate voltage down even more to allow safe usage of those tubes.

Hope this helps!!

Have you looked at the OD trim? It might be down or may have come loose. Also, it is possible that a tube went bad. Also, the clean channel gain affects the drive channel as well.

That looks very cool! I may have to build one of those...

Hey Ulf

The NFB Loop is found on V1. It comes out of Pin 6, through a 22M resistor, through a 0.05uF capacitor, and up to the terminal marked B-12, just in front of V1

i attached a pic for ya!

Also, as far as mods go, I added another one today by bypassing the HRM tonestack, thanks to user rogb, who confirmed my suspicion that bypassing the HRM tonestack is very simple. I like it better already. I need to put a switch on it, though so i can switch it in and out. I may even out a three way switch so i can have it bypassed, HRM Bluesmaster style through the 100R resistor, HRM Style straight to ground, to see if there are any sonic differences.
Gregg

Is Saturday Spam Day her on Ceriatone Forum?

i think his concern from what i gathered was that the AB763 circuit almost always had reverb and or tremolo. So, he would have to either ship reverb pans or have the customer source them, and build tremolo circuits specific to that circuit as well, that. Also the AB763 circuit has about 5 or 6 different variations that i can think of: The 15w Princeton Reverb 1x10, The 22w Deluxe Reverb 1x12, The 40w Super Reverb 2x10, The 40w Super Reverb 4x10,The 40w  Vibroverb 1x15, and The 85w Twin Reverb 2x12 each with their own power and output transformers and other  little quirks; not to mention all the Diaz and other mods that can be done to em. I think that they would sell just as well as the Overtone Series, and with just as many models as well, and I think Nik and the crew are at capacity now. Maybe if he expands one day he can do it, though. I hope he does, because even though there is a great local blackface guy here in FL (Vintage Sound) his amps are a little out of my price range right now ($1,295 for a fully assembled 1x12 Princeton). Also, AFAIK you have to buy it fully assembled from him, cab, speaker and all, no kits that i know of, but he will do custom mods and is very easy to deal with, very patient, just like Nik.

Now that i think of it, Nik never seems to sleep, Could it be he runs Vintage Amps and Ceriatone and has access to time travel and/ or teleport technology?? lol

Nice!!

Pretty Amp, and Guitar!

sweet!! looking forward to seeing how it all works out. I'm looking at some various preamps from Quinn, of course, and randall's modular units

Very Cool! So i Am thinking straight today! Woohoo 

Did you ever get that switching system for your Stock and Quinn Preamp hooked up?

any chance if selling to someone in the U.S.?? 

SO I am thinking about picking one of these up so I can run some effects parallel mode, and still use the C-Lator as i currently do as a global master volume/ sound enhancer. Am I thinking correctly that in order to use both the C-Lator and the mini mix like i want you hook it up like this?

Preamp Out=>C-lator In=>C-lator Send=>serial effects (if any)=>Mini Mix in=>Mini Mix Send to effects=> Mini mix return from effects=>Mini Mix Out=>C-Lator Return=>Power Amp In

Or

Preamp Out=>Mini Mix in=>Mini Mix Send to effects =>Mini Mix Return from effects =>Mini Mix Out=>C-lator in=>C-lator Send=>Serial Effects (If any)=>C-lator Return=>Power Amp in

I'm thinking it's option 1, but i have been known to be wrong before

Thanks for any help

Gregg

+1 for The AB763 Circuit. Nik told me he was working on it at one time, but i think he has had alot of business lately and is working on the Mini Amp designs now too. Maybe one Day

Greg, are you using the JAN NOS Short Plate Ge's or the Standard NOS?