Loving my JM style build. Need for a 1/2 power!

[imo1]

Hey everyone,

I had the chance to build a couple of Dumble inspired builds in the last month. The first one I built was basically an OD with the 1 tube reverb. Ive been messing with that tone stack, and think I'm currently with the 150k slope bigger pots on mid and bass(from memory 500k and 100k). That amp sounds awesome, but I'm generally a single channel amp player.

The other amp I made followed The JM layout relatively closely, outside of a few tweaks here and there. Used Taylor's chassis and boards, which saved me a lot of metalworking/labeling headache and were very thoughtfully put together.

I flew the amp down to Texas to start my tour, with the first show last night. The amp sounds amazing, really in line with what I've been going for for a long time. We played a pretty big outdoor venue last night and I brought a plexi screen. Even with that, and the giant stage, it was still a challenge for the soundman to work around my sound. My sound sits with the "master" around 70% and the gain a little under half. It's a perfect sound that allows me to play the style I have defined for quite a while. That said, I wish I had put a halfpower switch in the amp, and will be doing so when I get it back home after this tour.

Just wanted to put that out there for other players. If you are using it in similar ways to me, I would encourage you to do so! It sounds phenomenal, but it is loud!!

[erwin_ve]

Is turning the master pot down not an option?

[ijedouglas]

That said, I wish I had put a halfpower switch in the amp, and will be doing so when I get it back home after this tour.

Just wanted to put that out there for other players. If you are using it in similar ways to me, I would encourage you to do so! It sounds phenomenal, but it is loud!!

You can pull 2 tubes and basically get the same result as a half power switch. You may want to adjust your speakers so that they match the output transformer impedance. If you have an 8 Ohm cab, use the 4 Ohm tab (if available) on the amp.

[ayan]

That said, I wish I had put a halfpower switch in the amp, and will be doing so when I get it back home after this tour.

Just wanted to put that out there for other players. If you are using it in similar ways to me, I would encourage you to do so! It sounds phenomenal, but it is loud!!

You can pull 2 tubes and basically get the same result as a half power switch. You may want to adjust your speakers so that they match the output transformer impedance. If you have an 8 Ohm cab, use the 4 Ohm tab (if available) on the amp.

What Ian said and, to be safe, check the bias after you've pulled out two tubes, as the power tubes plate voltage will likely go up a pinch.

Gil

[imo1]

Is turning the master pot down not an option?

The sound of the amp, at least to how I use it, is really dependent on the master volume. It drives the PI and really changes the sound pretty significantly. I realize a lot of people here have a defined "clean" and "dirty" sound, whereas I am often looking for more of a clean-esque sound that is a bit dirty when I dig in. I really like what this amp does, but need to turn it up to do so.

[imo1]

That said, I wish I had put a halfpower switch in the amp, and will be doing so when I get it back home after this tour.

Just wanted to put that out there for other players. If you are using it in similar ways to me, I would encourage you to do so! It sounds phenomenal, but it is loud!!

You can pull 2 tubes and basically get the same result as a half power switch. You may want to adjust your speakers so that they match the output transformer impedance. If you have an 8 Ohm cab, use the 4 Ohm tab (if available) on the amp.

What Ian said and, to be safe, check the bias after you've pulled out two tubes, as the power tubes plate voltage will likely go up a pinch.

Gil

Yes! I'm planning on doing this tomorrow as we are playing more of a club show and its a smaller venue. I just think the nature of this amp is such that having a half power switch is a bit of a necessity in the long run

[imo1]

Again, its a bit of a dilemma, because part of what makes this amp stand out to me is the power of the low end. It is amazing how solid it stays. I'm using it with vintage 30's right now and realize that i need to get some higher wattage speakers as well.
The amp reminds me a bit of a really cool sounding twin. It has a sweeter sustain, but has a lot of the characteristics that I associate with a great blackface twin. I grew up playing super reverbs, so there is a spongey component that is different, but i dig it.

[romberg]

The sound of the amp, at least to how I use it, is really dependent on the master volume. It drives the PI and really changes the sound pretty significantly. I realize a lot of people here have a defined "clean" and "dirty" sound, whereas I am often looking for more of a clean-esque sound that is a bit dirty when I dig in. I really like what this amp does, but need to turn it up to do so.

I know it is considered a bit heretical, but you can install a PPIVMV in addition to the normal pre-PI master and then overdrive the PI at a reasonable (even bedroom) volume level. I did this on my ODS build and can confirm that you can even overdrive the PI with just the clean channel pushed fairly hard. If you install a Larmar PPIVMV it is electrically the same as not being there at all when turned all the way up.

Mike

P.S. Going 1/2 power will only reduce the overall percieved volume by 3db. You will barely be able to notice a difference.

[erwin_ve]

Is turning the master pot down not an option?

The sound of the amp, at least to how I use it, is really dependent on the master volume. It drives the PI and really changes the sound pretty significantly. I realize a lot of people here have a defined "clean" and "dirty" sound, whereas I am often looking for more of a clean-esque sound that is a bit dirty when I dig in. I really like what this amp does, but need to turn it up to do so.

I can understand your point of view.
Maybe you can try a bluesmaster PI setup? A bluesmaster PI does break up a lot earlier.

Erwin

[Guy77]

Is turning the master pot down not an option?

The sound of the amp, at least to how I use it, is really dependent on the master volume. It drives the PI and really changes the sound pretty significantly. I realize a lot of people here have a defined "clean" and "dirty" sound, whereas I am often looking for more of a clean-esque sound that is a bit dirty when I dig in. I really like what this amp does, but need to turn it up to do so.

Another option is to place the 68K resistor on a switch so that you can switch in another resistor to decrease the amount of signal that bleeds off to ground. This 68k comes right after the 1M resistor in the layout. By decreasing the amount of signal bleeding to ground you will notice you will get the "clean-esque sound that is a bit dirty when I dig in" at lower volumes.

Cheers

Guy

[imo1]

Is turning the master pot down not an option?

The sound of the amp, at least to how I use it, is really dependent on the master volume. It drives the PI and really changes the sound pretty significantly. I realize a lot of people here have a defined "clean" and "dirty" sound, whereas I am often looking for more of a clean-esque sound that is a bit dirty when I dig in. I really like what this amp does, but need to turn it up to do so.

I can understand your point of view.
Maybe you can try a bluesmaster PI setup? A bluesmaster PI does break up a lot earlier.

Erwin

Thanks Erwin. The thing is, I'm so happy with the sound of the amp, and a big part of that is the power of the low end. I would be hesitant to do anything that compromised those characteristics!

[imo1]

The sound of the amp, at least to how I use it, is really dependent on the master volume. It drives the PI and really changes the sound pretty significantly. I realize a lot of people here have a defined "clean" and "dirty" sound, whereas I am often looking for more of a clean-esque sound that is a bit dirty when I dig in. I really like what this amp does, but need to turn it up to do so.

I know it is considered a bit heretical, but you can install a PPIVMV in addition to the normal pre-PI master and then overdrive the PI at a reasonable (even bedroom) volume level. I did this on my ODS build and can confirm that you can even overdrive the PI with just the clean channel pushed fairly hard. If you install a Larmar PPIVMV it is electrically the same as not being there at all when turned all the way up.

Mike

P.S. Going 1/2 power will only reduce the overall percieved volume by 3db. You will barely be able to notice a difference.

I did think about putting a true master volume in it. I will look up that particular version. I am pretty fond of the setup that Samson uses. I remember cloning my old Clubman and being really impressed with how the master scaled

[imo1]

Is turning the master pot down not an option?

The sound of the amp, at least to how I use it, is really dependent on the master volume. It drives the PI and really changes the sound pretty significantly. I realize a lot of people here have a defined "clean" and "dirty" sound, whereas I am often looking for more of a clean-esque sound that is a bit dirty when I dig in. I really like what this amp does, but need to turn it up to do so.

Another option is to place the 68K resistor on a switch so that you can switch in another resistor to decrease the amount of signal that bleeds off to ground. This 68k comes right after the 1M resistor in the layout. By decreasing the amount of signal bleeding to ground you will notice you will get the "clean-esque sound that is a bit dirty when I dig in" at lower volumes.

Cheers

Guy

I would love to look into this more. I guess i could temporarily install a switch without drilling. The issue I always run into is that what works in the studio is often shown to be different when you get an amp in a series of different rooms, so when I make decisions based on that controlled environment I often have to come back and change them(thus the taking the amp on the road "as is"

[imo1]

Here is a short clip where you can hear the amp “clean” from last night! I love it, it’s just really loud.
I’ve always struggled with using 6v6s in this type of circuit, but curious if anyone who has built a similar circuit has any thoughts. To me, the 6v6 really works for that crunch, whereas the 6l6 has a smoother breakup

https://vimeo.com/697458177

[Chris Brown]

A Dumbleator in the loop is the only thing that has worked for me to get true lower volumes and still have the sound I like.

Right now I have a 100w with half power switch, one without, and a 50w... I have experimented with it quite a bit and the main difference with half power is clean headroom and low end response at higher volumes. It's still loud, and if you dial it down to quieter volumes it's really not much different than 100w dialed down low. When it's set where I like it, it's definitely not different enough in volume from 50w to 100w to please a picky sound engineer.