[Charlie Percoco]

Hi everyone! Maybe someone on this board can answer this question for me .I have an orginial MG-Head DT,stocked with 2 Zenith Radionic EL-84's(with blue dots on the bottom) and a Sylvania 12ax7,I'll be getting some Mullard,Telefunken and Bugle Boy 12au7's and would love to try them in this amp. Now I have heard arguments for and against for swapping these two tubes,but input from other MG-Head owners would really be helpful. Thanks All

 

[MagusG]

could a mod move this somewhere?

 

[daycart1]

Joe Lau, the ASL designer has posted on this forum saying that the MG Heads will work fine with any 12A*7 tube. Gain will differ some. I don't think these types have different sonic signatures, so you'll have to experiment with individual 12AU7. Post your results (in the amp forum).

 

[AndrewB]

The main difference between 12A*7's is gain and microphonics.

I've run AU, AX, AT, CV4004 from Mullard, Telefunken, Sylvania, Sovetek, Ei, JJ Tesla, GE, Amperex, ITT and others. T
he most significant differences were:
A) Higher Gains

The higher gain tubes brought out scratchy-ness in the volume pot
B) Lower Gains

required turning the Volume control much higher for decent volume

C) Swapping the 6BQ5's will also offer a significant performance change in the MG DT & DT/OTL as well

Have fun,
Andrew

 

[timoteus]

Quote:

I'll be getting some Mullard,Telefunken and Bugle Boy 12au7's and would love to try them in this amp.

If your going to be getting a selection of 12AU7 tubes all at once to roll, you're in for a lot of fun.

I've rolled probably 30-40 different 12AX7, 12AU7, 12AT7, 5751, 7025, and 7062 in my original model DT. Of all these, an old shield logo Mullard 12AU7 was definitely in the top five, maybe even the top three. Enjoy!

 

[utep10]

Of the different variations, which of the 12A*7 has the highest gain? Would these sacrifice alot of sound quality for gain say versus many of the 5751 variations mentioned on this forum (Sylvania, Raytheon, GE)?

Thanks,

Bruce

 

[timoteus]

Here are some gain factors for comparison:

12AX7 = 100
5751 = 70
12AT7 = 60
12AU7 = 20