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Old 05-02-2009, 05:00 PM   #219 (permalink)
solarburnDSL50
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Re: Preamp Tubes? - Who, What, When, Where, Why, and How?

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Originally Posted by MartyStrat54 View Post
I spent a good part of yesterday afternoon testing and recording tube ratings. I was surpised to find out that I had many AX7's in the "above average" ratings and I even had some that were up there with the ICBM. I have six, super strong Raytheon BP's coming in and I will need to test these tubes as well. I bought two lots of new tube boxes. I got tired of having all of these unprotected, loose tube lying around. I should have them in by the time I start shipping everyone's tubes out. Kevin is going the full Monte and getting four tubes.

Joe, I wonder if your 5751 is good? I'm sure you will agree with me that it isn't normal for the AT7 to outperform the 5751 in the gain category. Something is amiss. The tube may be weak for a variety of reasons. I have two 1958 Tung-Sol 5751's and they will outperform and of the AT7's that I have and I have some really hot ones such as JAN (Joint Army/Navy) 12AT7's that are some of the best I ever have had. I bought a box of five and I'm using one as the PI in my old Randall hybrid amp with the 8417 power tubes. It works great in there.

The way I see it, having an AT7 in V1 will work as long as you don't (as you say) crank the gain more than twelve o'clock. In this situation V2 will have enough gain reserve to compensate for the lower gain of the AT7. The result is a completely different sound. On the other side of the fence is putting two super gain 12AX7's in V1 and V2. This is a raging animal that is waiting for a hard power chord followed up by some feverish licks. The tube harmonics I got with two hot tubes was incredible. It made my power tubes sound better as well.

To each his own. I know I'm getting old and I don't play as good as I used to, but I still like the high gain sound. I learned on another thread that the choke mod works better with 100 watt heads than say a 40-60 watt head.
One thing about tube mods, they work well on any size amp.

Marty
You may be right about the 5751 not being a good one. It dulling the tone up like it did surprised me. Maybe I'll mess with it again and see if I get anything different out of it. It was a quick demo I did of it cause it was like yuk!

I think the CV4024 mixed in creates a midgain sweet spot that I like. That being said I haven't got to really crank it up for more than a few moments due to the father-in-law living with us. It limits my ability to get a good feel for these tube changes at a good volume although I do torture the household here and there. Like I said though using them(CV4024)still is experimental. I haven't really settled on having an AT7 in there all the time. It can sound good though. I think the PI may be a better position for it. I don't know yet.

Those NOS tubes you gave me livened things up a bit today. Its been awhile since I played at high gain. It was righteous! Marshall wanted to take off! What is nice about them is the guitar roll off still sounds good too. I stepped on the Germania to add even more and it was reeling mad then. Wow how fun was that? Very! Felt like I needed a cig cause I just had sex.

I just woke up from a nap so I have to mess around with them more and I am definitely interested in all these NOS tubes I'm learning about. Really cool stuff. I wonder how the NT will like em'? Stay tuned. I can't wait to get the EL84's from you. I've been pricing some NOS and ouch are they spensive. What do you think of this site?:

KCA NOS Tubes. Audio tubes for guitar amplifiers and audiophile equipment. 12AX7, 6L6GC, 12ay7, el34, el84, Fender amplifier,5AR4, 5U4GB, cv4004, 6SN7, 8417, 7027, gz34, Mullard, EF86, 6ca7, 6bq5, 7025, 12at7
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My mids are always on 10. But then, I'm playing "anti-scoop" metal. Ken
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I'm sure you will agree with me on this...

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