Experimenting with the mods and valves

[davo]

Hi all, I'm the new guy around here, I've read a whole bunch of posts over the last couple of weeks and I just want to say thanks for all the info that I have gleaned from the forum, I feel I understand my amp so much more now. I have owned my LS classic for a bit over 2 years and love it to bits, and like a lot of people chnl 1 is amazing and chnl 2 ...well not up to the same standard so I tried the Reeder Mod #1 & Mod #2 on chnl 2 and I love it, chnl 2 is so much sweeter now, Mr Reeder thanks for the tips. I also understand that some of you guys have swapped out some of the preamp tubes for ones with less gain. OK so I can understand swapping out the V2 position for say a 5751 valve but I don't understand what the phase inverter/driver valve (V5) does or why it would benefit from a different gain tube like a 12AT7, Can any gurus shed some light or steer me in the right direction with some info.
I'm keen to experiment with some different speakers next but I want to tinker with the valves first.

Thanks guys
Dave

 

[djw]

I think of it this way: if you use lower-gain preamp tubes in certain stages, you'll then have to push the power tubes a little harder to maintain a similar output level. This is good because the main issue we seem to have is with getting the power tubes to a decently juicy state without causing lots of ear damage. This is one way, and like most of them the results are probably more subtle than we'd like. But it does work. The 5751 in V2 has a greater effect in my experience, and it also alters the tone in an interesting way.

 

[davo]

Thanks djw, I can certainly understand a lower gain tube in V2, I am actually trying a 5751 in that position now and I'm enjoying the results, I have to tweak the gain knob a little and I can appreciate that fact. I love the bluesy sweetness I'm able to achieve but what about the V5 valve, the phase inv/drv is there any benefit to swapping out that one out. Or maybe a better question would be "What does the V5 tube actually do?"

Thanks all for your help

 

[djw]

I think if I tried to explain it myself, I'd miss the mark... here's something to look at though:

http://en.wikipedia.org/wiki/Phase_inversion

How this affects tone varies from amp to amp, but again the basic principle in a lower gain preamp tube (including the phase inverter) is to lower the signal going into the power stage, making it necessary to drive your power stage harder to get to volume parity with an otherwise standard config. V1, V2 and V5 are all inline at all times so you can get different takes on this effect by lowering the gain in any of these stages.

 

[davo]

Again thank you for your response, that clears it up :? but seriously thanks, I feel I understand my amp so much more now. This is my first Boogie amp and the learning curve is some what steep and having a basic understanding of how the valves interact with each other really helps. It's deep enough trying to understand the tone controls and how they work together, I've never considered the tonal variations that can be realized by the tubes themselves.

Very helpful
Cheers

 

[jhendow]

I have used 12AT7 tubes in the preamp stages of several amps. I generally favor a clean tone with low-to-mid gain for leads. Most "modern" amps have excessive gain structure for my taste and I wind up dialing them back to get the sound I want. I also prefer the sound of 6L6s when they're pulling pretty hard on the incoming signal, so using a lower-gain tube in the preamp has the additional benefit of making the power tubes work harder.
I'm currently on the hunt for a Lonestar Classic 1x12, and my intent is to experiment with 12AT7s in the preamp.

 

[davo]

Hi John,
I understand what you mean by a lower gain preamp tube, I have to crank the amp a bit more which gets the power tubes to work a bit harder and I'm really enjoying this amp so much more. I mainly use the lower wattage setting on both channels and the band I'm in isn't a loud one so it really suits my style.

I'm just going to play around with this for a while before trying out some different speakers, I have managed to scrounge up a pair of late 60's greenback Celestions that are in great condition so I'm interested in hearing those.

Cheers
Dave