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ASL MG Head DT/OTL MKIII Tube Rolling Experience - Page 4

post #46 of 101
Thread Starter 
You guys are great! Learning some fun stuff here.
post #47 of 101
Thread Starter 
I tried out my Telefunken 12AU7 and it worked just fine. Of course, the gain was rather low. I had to turn the pot to 50% to obtain a decent level. No distortion or clipping was noticeable.

Is there any chance that having my volume set so high could cause any harm to the power tubes?
post #48 of 101
Quote:
Originally Posted by manofmathematics View Post
I tried out my Telefunken 12AU7 and it worked just fine. Of course, the gain was rather low. I had to turn the pot to 50% to obtain a decent level. No distortion or clipping was noticeable.

Is there any chance that having my volume set so high could cause any harm to the power tubes?
No .... the high volume setting is just a consequence of the low gain of the tube. If you need to turn up the volume even louder there will be a point where the tube can not meet the voltage demands, with distortion and eventually clipping as the result. Tubes clip very gracefully, unless severly overdriven, so you may not even detect the clipping until the effect is blatant.

Since this amp seems to be forgiving of a wide range of 12ax7 pinout tubes .... there are number of inexpensive 12ax7 pinout tubes, like the 12av7, that are very good sounding. Better yet, the 12av7 and 12av7 subs have a higher mu/ gain of 43-48 that should be more comparable to the mu/ gain of 70, of a 5751. These tubes have a heater current draw of 0.45 amps vs the 0.30 amps of a 12ax7/5751 .... which should be insignifigant. But, it would not hurt to contact ASL and ask. These tubes do draw a good bit more current.

What are these tubes? For the 12av7 you have the 5965/6414/6829 and 7062. You can also use the 12at7 and the 12az7 that were already mentioned.


Here is a list of all the 12ax7 pinout compatible tubes ....


NJ7P Tube Database Search
Tubes with base 9A

6AU7 6AX7 7AU7 9AU7 12AD7 12AE7

12AT7 12AU7 12AU7A 12AV7 12AX7 12AX7A

12AY7 12AZ7 12AZ7A 12BH7 12BH7A 12BZ7

12DF7 12DM7 12DT7 12DW7 12FV7 5751

5814 5814A 5963 5965 5965A 6057

6060 6067 6072 6072A 6189 6201

6201 6211 6211A 6414 6679 6680

6681 6829 6851 6913 7025 7247

ECC81 ECC82 ECC83
post #49 of 101
Thread Starter 
sacd lover...I'm going to start myself a reference book with your posts...Thanks! I always appreciate technical information. Technical knowledge sure is my downfall.
post #50 of 101
I also use the very helpful NJ7P online tube database. But it does not always agree with the Tube Substitution handbook. The Handbook is nice because it lists direct subs as well as those that will work only in parallel circuits, ones that will work in series circuits, and ones that may work in some, but not in all circuits. Further, it very nicely lists them in the proper "direction", meaning that sometimes tube B can be used in a circuit designed for tube A, but tube A cannot be used in a circuit designed for tube B.
post #51 of 101
Thread Starter 
Where can I pick up a copy of that book skylab?
post #52 of 101
post #53 of 101

What's Wrong With...

What's wrong with using Duncan's Amps Tube Data... and... his related links - it's free?

TDSL Tube search

I mean... "I'm just sayin'"...
post #54 of 101
Thread Starter 
Nothing wrong with it, and thanks for the link!

I do like my books though.
post #55 of 101
Hey Mano,Brent Jesse over at BRENT JESSEE RECORDING HOMEPAGE has a pair of 1956 Amperex "D" getter El84's.Nice tubes and 30 day warranty.
post #56 of 101
Thread Starter 
Thanks for sharing the link Fairbanks.
post #57 of 101
So where does everyone stand on the current (top rated) tube combo on your ASL MkIII amps?

Just dug mine out, and will be taking it to work. I will be sourcing it with the Laptop or my Creative Zen. Pushing my ETY 4S.

I am still with Stock tube setup. Playing with other things right now. But would be interested in playing with this amp more.

Cheers,
post #58 of 101
I have an older version, but my favorite combination is actually the Raytheon 5751 windmill and a pair of Mullard 7189 power tubes. The Raytheon is punchy and deep, while the smooth Mullards have enough low end to support the real strengths of the Raytheon. I have a pair of Amperex el84's that don't match up as well because their higher tonality messes with the Raytheon. The Amperex el84's mated rather well with the Sylvania Gold Brand 5751, until mine died.

The best advice I can give is to try out different combinations, because each listener likes different tonalities. I like a deep and punchy sound, thus my favorite combination, while others like a more forward, brighter colored sound. Nothing wrong with either, just preference. Try out a 5751, that will take your sound to the next level.
post #59 of 101
There was a thread started long time ago by one of our always missed moderators, and a very knowledgeable guy, despite fo being a young fellow, Nick Dangerous, and very nice guy.
He did some tuberolling to this little magic amp, specially for the HD600, BTW one of my first entrance level amps, here is the website with the article, nice funny reading, if you want to find out more about tubes for that particular amp...So far the best I could find at that time was the Windmill getter Raytheon, and a couple of JJ...and the sound as very nice, until I got the CD3K, which this amp is not a match at all...
post #60 of 101
Thanks for the link Sov... good read and good information.

Cheers,
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