Can I use 12AT7?

Ahmad_tbp · 20th January 2006, 06:10 PM

hi all ..
i m tryin to build the " Real McTube " pre amp ...
u can find the layout and schematic here :

http://www.tonepad.com/getFile.asp?id=43

info site :

http://www.dogstar.dantimax.dk/tubestuf/mctube.htm

... in the site said that it was designed for 12AX7, but usable with any similar twin triodes .. so can i use 12at7 ???

thnx

Giaime · 20th January 2006, 06:17 PM

Hello!

Well, my "hi-fi" answer would be NO. You can't use a different tube: you'll have different operating points, gains, etc etc and the stage won't behave as it has been designed.

My "guitarist" answer is YES, and that's good to use a slightly lower gain tube in the RealMcTube (Rest In Peace Fred). You're not going to hurt anything, so try and see if you like it better. In those sorts of tube stompboxes, you REALLY want to get as many tubes as possible of different flavours (12AX7, 12AU7, 12AT7 but even others) just to hear how it sounds.

Though I don't like 12AU7 flavour, it sounded best in a guitar preamp that I prototyped (very similar to the RealMcTube). Much less gainy and more bluesy sound, opposed to a fuzzy cold 12AX7 sound. I won't expect the 12AT7 perform so different than 12AX7, gain is still too high.

Eli Duttman · 21st January 2006, 01:25 AM

Just keep the differences in character between the 'X7 and 'T7 in mind. The 'X7 is high Rp/low gm, while the 'T7 is high gm/low Rp.

The 5751 has a mu of 70 and it will replace the 'X7 without incident. The 12AY7 has a mu of about 40 and it may drop in too, as it also has the high Rp/low gm character.

Ahmad_tbp · 21st January 2006, 07:53 PM

hi and thnx a lot

.. so i can use diffrent tubes .. i wanna use these pre in a guitar amp , and i need high gain for metal music ... so i think the best choice for me is 12at7 .. thanks

ivegotmono · 21st January 2006, 08:28 PM

Hi,
If it's gain you want, stick with the ax7, the lower gain tubes t7,y7,u7
will distort later too. Some people like less gain in order to force the distortion into the power tubes. Matter of taste and music style. Try em.
Steve

Giaime · 21st January 2006, 09:31 PM

Hello!

If Metal is your thing, the VERY BEST option is to cascade 2 RealMcTube with 12AU7 in both and with an equalizer in between!

Ahmad_tbp · 25th January 2006, 06:11 AM

two real mctube w eq ?

...
sounds great ... but i don have 12au7 ...

and idea for a guitar eq ?

20th January 2006, 06:10 PM	#1
Ahmad_tbp diyAudio Member Join Date: Jul 2004 Location: Iran/Shiraz	can i use 12at7 ? hi all .. i m tryin to build the " Real McTube " pre amp ... u can find the layout and schematic here : http://www.tonepad.com/getFile.asp?id=43 info site : http://www.dogstar.dantimax.dk/tubestuf/mctube.htm ... in the site said that it was designed for 12AX7, but usable with any similar twin triodes .. so can i use 12at7 ??? thnx __________________ Rest my eyes from the world. This dying place, it's so absurd.

21st January 2006, 01:25 AM	#3
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	Just keep the differences in character between the 'X7 and 'T7 in mind. The 'X7 is high Rp/low gm, while the 'T7 is high gm/low Rp. The 5751 has a mu of 70 and it will replace the 'X7 without incident. The 12AY7 has a mu of about 40 and it may drop in too, as it also has the high Rp/low gm character. __________________ Eli D.

21st January 2006, 07:53 PM	#4
Ahmad_tbp diyAudio Member Join Date: Jul 2004 Location: Iran/Shiraz	hi and thnx a lot .. so i can use diffrent tubes .. i wanna use these pre in a guitar amp , and i need high gain for metal music ... so i think the best choice for me is 12at7 .. thanks __________________ Rest my eyes from the world. This dying place, it's so absurd.

21st January 2006, 08:28 PM	#5
ivegotmono diyAudio Member Join Date: Nov 2005 Location: maryland	Hi, If it's gain you want, stick with the ax7, the lower gain tubes t7,y7,u7 will distort later too. Some people like less gain in order to force the distortion into the power tubes. Matter of taste and music style. Try em. Steve __________________ steve

25th January 2006, 06:11 AM	#7
Ahmad_tbp diyAudio Member Join Date: Jul 2004 Location: Iran/Shiraz	two real mctube w eq ? ... sounds great ... but i don have 12au7 ... and idea for a guitar eq ? __________________ Rest my eyes from the world. This dying place, it's so absurd.

20th January 2006, 06:17 PM	#2
Giaime diyAudio Member Join Date: Oct 2004	Hello! Well, my "hi-fi" answer would be NO. You can't use a different tube: you'll have different operating points, gains, etc etc and the stage won't behave as it has been designed. My "guitarist" answer is YES, and that's good to use a slightly lower gain tube in the RealMcTube (Rest In Peace Fred). You're not going to hurt anything, so try and see if you like it better. In those sorts of tube stompboxes, you REALLY want to get as many tubes as possible of different flavours (12AX7, 12AU7, 12AT7 but even others) just to hear how it sounds. Though I don't like 12AU7 flavour, it sounded best in a guitar preamp that I prototyped (very similar to the RealMcTube). Much less gainy and more bluesy sound, opposed to a fuzzy cold 12AX7 sound. I won't expect the 12AT7 perform so different than 12AX7, gain is still too high.

21st January 2006, 09:31 PM	#6
Giaime diyAudio Member Join Date: Oct 2004	Hello! If Metal is your thing, the VERY BEST option is to cascade 2 RealMcTube with 12AU7 in both and with an equalizer in between!

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