Tubes - Need new ones I think

I'll take one last chance and am not looking this up while writing, but will look it up after the post. I just came from my semi-hotroodded Blues Deluxe pulling tubes and checking on your behalf.

As stated with the link to the Tube Store which I gave earlier, that was meant to be professional advice and not from 40-year self-taught amateur (hobbyist willing to take on serious projects and tests) like me... you could go with 2 12AT7's in the preamp section instead of the 12AX7-A's to calm it down and provide less preamp gain, where you have plenty to spare. A Jan Philips 5751 is better and will take you to 70 percent gain factor, to be exact, and should make things perfectly clean. My 12AT7 swap gave me only 60 percent gain, or similar to a 42 Watt amp from my Super 60, except the math doesn't actually work that way, since I have my own decibel meter, (but no Oscilloscope, because I use my ear in intonation) and usually purposefully keep things loud while still clean, because clean is loud and boosts decibels, whereas clipping is just noise and cuts measured volume. Cleaner power lets you choose low volumes when desired, I'd say.

http://thetubestore.com/gainfactor.html

With a few tricks, nothing other than things that the pros know, (but I call Rock It Science), I get the loudest guitars around, sounding clean and clear, while sweeping the decibel meter off its scale at over 126 with a 15 Watt amp turned to less than 4, and OMG it hurts the ears, but it's clean. Clean hurts when its loud, take my word. Distortion lowers decibels but is so dirty that it just destroys an eardrum (tympanic membranes) and it blows or fraps out a speaker.

This swap excludes the reverb tube which is closest to the Power Tube duo, and sitting inbetween and on its own.

I went from 12AX7A's and 7025's which are the same thing to lighter AT7's on my Super 60, and didn't have to - they totally quieted the thing down, and I wanted it both clear and loud, and true to guitars' tone which it already was - so it was fine and I changed it to the mild side unnecessarily. But that was before I got my 40 Watters, and the Super 60 is exactly 20 years old, or maybe 22 if it was old stock.

Later: so here's a link, you can find more, and this guru forgot the 5751 which should have been between the middle and to the right of his chart at 70 percent, and ideal IMO. http://reviews.ebay.com/Guitar-Amp-Tube-Substitution-Guide-change-your-tone_W0QQugidZ10000000006463359 here's the REAL scoop by the undisputable pro, who actually made the bias kits, and he did NOT miss the 5751 - he's too good. http://www.torresengineering.com/realinonprea.html

I don't think you need to ADD a bias kit and re-bias the fixed bias. I will check this out, and reply, or let somebodsy else state otherwise and make my advice wrong or inappropriate, if that is the case.

I will take some time off so that others may always have a shot at your problem, if interested and available to help.

Okay, so my advice doesn't blow you up and cause problems, I believe that you only bias the Power Tubes, and you don't have to do it. As we've covered, your bias is fixed, but need not be checked for your pre-amp swap. Also, the power duos in a push-pull circuit, even where there are 4, or a quad, are paired in sets of two... they are the ones in pairs that should preferably be matched, and you don't have to change them with your problem, unless they are faulty.

GT pre-matches their tubes with a number, on the Power Tubes. http://www.groovetubes.com/

http://www.diyguitarist.com/GuitarAmps/PT-Biasing.htm

Here it will state that your smaller preamp tubes (and reverb) are pre-biased, so no worries.

http://www.roccaforteamps.com/tube_bias.htm

Here are all the answers from who else, the Tube Store, my favorite source.

http://thetubestore.com/powertubeinfo.html

Next day: hehe I re-read my posts and everything still stands, but I found some mistakes which will not affect your amp or the tone 'dilemma', as I called it before.

When I switched my 12AX7's to AT7 on my Fender Super 60, I got LESS than a 40 watt amp, now I see why - "I" did the math wrong. :oops: The AT7's have a 60 percent gain factor, and were not 5751's with a 70 percent gain factor, so it was more like a 36 watt amp - no wonder it produced less than my newer 40 watt amps. However it handled "10" easily and was raw and bluesy at that level, without blowing up or sounding insane. It became a very useful amp for that effect, without destroying it.

I suggest that you replace your 2 preamp tubes with 5751's. Again these tubes are prebiased, and your amp will not have to be biased. And biasing seemes to apply to Power Tubes. BTW, there is much latitude at the Power Tubes too. A fixed bias amp can adjust, or the cathodes in the tubes will adjust themselves to the bias (see links above), unless there is a great disparity, ie. overpowering, and that would not be the case with a 30 percent difference, IMO. I have biased biasable amps that were calibrated wrongly, or over-calibrated (overpowered) for their tubes, to a wider margin. They made squealy noises and were raspy. Turning their trimpots and biasing by ear fixed that.

You wouldn't have to test your tubes unless you strongly don't trust them. The problem is that they have too much gain factor in that Hot Rod amp to produce the cleanest and purest of tones.

Again, it is very interesting that Groove Tubes label their tubes with a number at which they are supposed to break up. I suspect yours are a low number - I used to have the same but sold it.

I didn't abandon the concept. I got a Blues Junior 15W, w/12" spkr.

And I bought another Blues Deluxe and "Hot Rodded" it as I said.

The Hot Rod series amps just want to break up too soon, IMO. :lol:

HRD with strong, hard-driving Rio Grande Fat-Bottom single coils and SD '59 and JB Buckers, not clean/true enough...


It also loudened, ruined or muddied what should have been clean & airy, bright & glassy or jangly Gretsch Filtertrons:

The 45 Watt Super Reverb was the perfect clean and very versatile amp, pushing 4-10's w/a lot of air, but too heavy!

Many people in the Blues/Pop/Surf scene use it - either true vintage or Black Face re-issue if they can lift and transport.
It has reverb and vibrato, and I did tube changes during its time to keep it at peak operating condition or performance.

BlueJay thanks for the response.

OK I posted a reply and it went to never never land. Anyway so from what I think you said I wouldn't have to bias the amp if I changed the tubes on the Fender Deluxe as long as I kept the tubes within a certain range( find that info on Tubestore website)

But when I went to one of the other links the diyguitarists.com I'm kind of reading that there still is biasing that needs to be done.

I'm hoping that I can: Buy new power and preamp tubes (different than stock) and replace them without having to bias the amp.

Is this true or will the amp not be tweaked to maximum performance without the biasing?

Sorry for all the questions

BlueJay thanks for the response.

OK I posted a reply and it went to never never land. Anyway so from what I think you said I wouldn't have to bias the amp if I changed the tubes on the Fender Deluxe as long as I kept the tubes within a certain range( find that info on Tubestore website)

But when I went to one of the other links the diyguitarists.com I'm kind of reading that there still is biasing that needs to be done.

I'm hoping that I can: Buy new power and preamp tubes (different than stock) and replace them without having to bias the amp.

Is this true or will the amp not be tweaked to maximum performance without the biasing?

Sorry for all the questions

Yeah, you're definitley welcome; and I was adding some pics there as you replied, wow, same time! I didn't change any facts.

You can change all of your tubes to types suggested by the tube store without re-biasing or ruining anything. It's all win win.

When speaking of peak performance, the assumption is that you have to crank it to get the most volume you'll need, so you can use 70 percent preamp tubes, the 5751's, and still have power or volume on tap when needed.

So, the performance isn't peak in terms of levels and distortion, but would be optimal in terms of usefulness and being practical and viable, so it's optimal for customer satisfaction, and user-friendly IMO. :D

Blue Jay, that sounds good to me. I see on the Tubestore website they have a package specifically for the Fender Deluxe which is what I will probably end up getting.

I'm gonna keep my fingers crossed and see what happens.