Question about some preamp tubes

[tomas_almeida]

Hello TBers.

I'm going to buy a tube amp, and I'm going to have the preamp tubes replace with two 12AT7. I've found a Mullard pair, but I can't see any pins on them.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=220312224735&ssPageName=MERCOSI_VI_ROSI_PR4_PCN_BIX_Stores&refitem=380085277885&itemcount=4&refwidgetloc=closed_view_item&refwidgettype=osi_widget&_trksid=p284.m185&_trkparms=algo%3DSI%26its%3DI%26itu%3DUCI%26otn%3D4%26ps%3D41

Would they fit in a preamp section? Is that black thing some kind of protection for the pins?

 

[bongomania]

Yes, that's just a protector, it comes right off. The pins are the same on all 12AT7's.

 

[AxtoOx]

OK, I'll bite. Why not use 12AX7's like most of us do?

 

[BassmanPaul]

Yes the black plastic blocks the tubes are mounted on are to protect the fairly fragile pins.

Why on earth would you want to replace the existing pre-amps tubes before you even know how the amp sounds??? What amp are you buying?

Paul

 

[tomas_almeida]

Ok thanks for clarifying that to me.

AxtoOx, it's for a Traynor YBA 200. This amp has a circuit that cuts mids depending on how low the gain is. This will be to reduce the gain of the preamp so that I can turn the gain knob and not have the preamp clip. In the long term I tend to take it to a technician to see if he can take out that mid cutting circuit.

 

[AxtoOx]

Ok thanks for clarifying that to me.

AxtoOx, it's for a Traynor YBA 200. This amp has a circuit that cuts mids depending on how low the gain is. This will be to reduce the gain of the preamp so that I can turn the gain knob and not have the preamp clip. In the long term I tend to take it to a technician to see if he can take out that mid cutting circuit.

Gotcha.

 

[Bassflute]

Ok thanks for clarifying that to me.

AxtoOx, it's for a Traynor YBA 200. This amp has a circuit that cuts mids depending on how low the gain is. This will be to reduce the gain of the preamp so that I can turn the gain knob and not have the preamp clip. In the long term I tend to take it to a technician to see if he can take out that mid cutting circuit.

Sure you want to pay for premium Mullards when you don't even know if this is going to work? Maybe borrow some first. Also, there's 12AU7's out there, in case you weren't aware - different gain again. Are you sure you'll get enough power out of the thing after this mod? It's not a terribly powerful amp to begin with. Maybe just look around for another tube amp - the new Orange one is very nice, or a really nice old Trace from the 90's. Both are quite a bit better and more powerful than the Traynor, and without the annoying midrange thing you're trying to avoid.

Cheers,
Cameron

 

[Rick Auricchio]

Have you considered actually using the amp for a while before immediately trying to modify it?

 

[tomas_almeida]

Yes, of course. I'm goint to use it for a while before I actually decide whter or not to buy the preamp tubes.

Bassflute, I dont need more than 200 watts tube (by the way, the Orange is 200 watts too). And I don't have the money to buy those amps you refered (and yes, I've been searching for an old all tube Trace for quite some time, but all of them ended up being sold too high for my pocket).
12AU7's have very little gain, too little in fact. And when I can I'll try to get some tech to mod that midrange thing. A TBer did that and said that his tech told him it had been easy.