2. amps-preamps
  3. 1282804225

I need a lower gain 12au7 for Mastersound

I recently purchased a Mastersound Due Venti. It has 2 JJ ecc82 gold pins in the preamp. I find them to be a little high gain for my tastes. They do sound quite nice though don't get me wrong.

Could anyone recommend a 12au7 or variant that naturally has less gain than the JJ but still retains quite a lot of detail and low noise? New or NOS, doesn't matter to me.

Any responses or suggestions would be greatly appreciated!
Or if anyone has a Due Venti maybe they could let me know what preamp tubes they prefer?

I'm running it with a pair of La Scala's, they're just a little too efficient maybe...

Thanks for your time!!
ddderek
detredwings
162 posts
 
The 5751 has a gain of 70 compared to the 12au7 gain of 19. I've never heard of using that in place of a 12au7. I do replace 12ax7's with them and like them.

As far as low gain 12au7's I don't know of one. Someone may give recommendations for a tube to try. If not you could put a simple two resistor voltage divider network on the input to your amp.
ddderek OP
9 posts
 
Thanks for the reply.
I guess I'm just looking for a tube recommendation, something NOS that has a reputation for a little less gain, but for sounding good as well.
Personally I don't really want to get into the amp and start soldering too much......

Thanks for the advice though!
rrog
1,958 posts
 
Are you sure those are preamp tubes? Mastersounds claim to fame has always been their passive gain stage. The 12AU7 tubes are drivers for the output tubes. Using one of the low gain alternatives will result in a very dull sound.

Apparently yours is a CD based system. What CD player are you using? Do you know what the output voltage is? If you want to cut back the gain someplace the source may be the best place to do it. The other alternative is a less efficient speaker.
allenwright
17 posts
 
There is no "lower gain" 12AU7. There are tubes with less gain but nothing that can just be swopped over without major wiring changes inside = very good technician = $$$.

La Scala's are way more efficient than the current norm, but can sound great.

The attenuator is the best idea.

Regards, Allen
hifiharv
351 posts
 
I'm no tech. expert, but I always thought the 12AU7 was designed as a "unity gain" tube. Meaning it does not provide gain at all. Usually used at the end of a preamp as a cathode follower to improve that circuit's ability to drive the cable and the next amplifying device. By experimenting you will probably find another 12AU7 that you " perceive" to have lower gain.
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