Conversion from 6L6 to 6V6

Andy67 · Posted: Sat Oct 25, 2008 9:32 am Post subject: Conversion from 6L6 to 6V6

Hi, this is Andy 67. I was wondering if I could change the 6L6s in my Fender Hot Rod Deluxe for a pair of 6V6s. I want the amp to break up sooner, have a "warmer" sound and I don't mind if I lose some power (40Watts is enough!!)Will I have to rebias the amp, even if I get a matched pair? May I have any other problems?
Thanks in advance,
Andy67

"There are only two kinds of music, Rock and Roll"

tw001_tw · Posted: Sun Oct 26, 2008 5:45 am Post subject:

Andy67 · Posted: Sun Oct 26, 2008 11:59 am Post subject:

Thanks so much for the help, it's been a great reading! As soon as I get the swapping done, I'll post the results. Once again, thanks a lot for the help. Keep on rockin' in a free world!!!

Andy67 · Posted: Fri Oct 31, 2008 11:38 am Post subject:

Hi, I got some really useful info from Jay at eurotubes, and he told me that I won't get any problems as long as I get a pair that are a grade #26 to #30, talking about JJ 6V6s. He says I won't have any problems with bias, and that I will have plenty of room to tweak it if I want to. The power will go as low as 25 Watts. He also recommended a 12ax7s in V1, a graded high gain 12ax7s in V2 and a balanced 12ax7s in the phase splitter hole to eliminate dead spots. He works only with JJ tubes, which I really trust (I've been using rectifiers and the result is great), as he is a dealer of these tubes. His info was clear, fast and, over all, sincere. I will trust him no matter what, and I'll get the set from him. He told me re-issue Tung-Sols are actually Sovteks, and that he only relies on JJs (I understand). Everything he says is really trustworthy.
I hope this helps some tone freaks like us!!
Keep on rockin' in a free world!!

"There are only two kinds of music, Rock and Roll"

thessandman · Newbie Alert Joined: 25 Nov 2008 Posts: 3

I swapped 6L6's for 6V6's in my amp. There were several things about the amp I didn't like. But, in retrospect, I think the tube switch did little to fix it. On my amp, at a volume of 3 it was loud, at 5 it was harsh, 6 and above it was nasty. I had the pots changed and it made a big difference. My amp tech changed the tone stack to make it more like a Bassman (he said that is what the amp is based on), and I changed the speaker. I put a Cannabis Rex in it. The amp sounds a lot like a vintage Bassman. Loud and rude, but not harsh. I am going to put the 6L6's back in it, looking for that sweet Fender clean. I've got a Tube Screamer for some grit.

So, after all this, if you are looking for some advice: what is it that you don't like about the amp? The tube change might not fix it. There are lots of things you can do to this amp, decide what you are looking for and go from there.

Hope this helped. You can PM me if you want to talk about it some more.

Tony

vibrofan · Not So Newbie Joined: 27 Nov 2008 Posts: 7

The Hot Rod Deluxe runs the plates and screens at 430V with a factory set bias of about 30mA idle current per tube for a cold class B opperation. The 6L6GCs would need to be warmed up to 48mA per tube to achieve an ideal class AB bias or 62.7mA for class A. Trouble is it's questionable your tranformers can handle these elevated currents without core saturation or overheating...

Swapping 6V6GCs into your amp without adjusting bias they should achieve a hot class A bias with about 30mA per tube. You might find this offers sonic advantages but make sure you don't exceed their maximum plate dissipation (VA) as this would vastly shorten your tube life even if they do sound good while they last.

Keep an eye on your tube's plates to see if they start turning red. If you see this you know you're exceeding the maximum dissipation and you need to settle down the bias. Sometimes under dim lighting you might be able to see the screen grid glowing red hot under the plate. Overheating the screen is the most likely way your 6V6s are goint to fail running in your HRD. Even in the absense of red plating you'll probably not get the best longevity out of 6V6s in your amp because of the lowish 470 ohm screen resistors but I suppose you don't drive a hot rod looking to get maximum mileage... you're looking for performance.

vibrofan · Not So Newbie Joined: 27 Nov 2008 Posts: 7

I wouldn't turn a cold shoulder on the EH tubes. JJ makes fine 12AX7s and EL84s but the EH / Tung-Sol / Mullard / Genalex labeled output tubes coming out of the New Sensor owned Reflektor factory in Russia are very fine tubes indeed. Excepting only the Western Electric's limited continuing US production and the European Audio Tubes (EATs) I'd say they've earned the rank of the finest current production tubes. I highly recommend the TS 6V6GT. The 5881 is another tube you should consider trying in your amp. They have a beautiful creamy overdrive and should swap right in without any need for adjustment.