Solo boosts and attenuators on a Dyne

I am using an eq pedal in the effects loop as a solo boost on my Dyne. It works great at low volume without an attenuator. However when I put in the attenuator (the hot plate), turn up the volume and wind on the attenuation, the solo boost does not seem to increase the decibels much. I can add up to 9db without getting much if any additional volume when I hit the boost. The tone changes, but the volume doesn't seem to increase. Does anyone have any idea what is going on please?

Once your amp is at maximum volume boosting it won't make it any louder...

An attenuator also compresses the dynamic range of an amp.

Yeah, that's the problem with pushing the power stage. You would have to back off the master by the amount you want to boost and run it like that.

Thanks for taking the time to respond. The thing I don't understand is why the amp stops responding to volume boost the higher I turn it up. At 1 on volume master on the amp, with 3db on the volume boost, it works fine. At 5 on the volume master, and 3db (or even 9db) on the volume boost, it doesn't increase the total volume. In both cases I am loading additional db into the power amp but the more I am pushing the power amp the less the total volume is increased by the volume boost. This seems to be the point that the dynamics of the amp are reduced as the volume goes up. Is there a solution to this? Do the volume boost switches that Mesa provide on some of their amps suffer the same problem or are they engineered differently please?

werdna said:

...I don't understand is why the amp stops responding to volume boost the higher I turn it up.

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Basically, your amp is at maximum SPL output at master=5. Anything beyond that is loading/pushing/distorting the power stage and is not contributing to additional volume output. The boost can only take it to "maximum", so if you start at max, the boost can't take it any further.

The Fulltone Fulldrive 2 pedal "suffers" from the same boost design limitation. You learn to work within the design envelope or you change gear.

werdna said:

Thanks for taking the time to respond. The thing I don't understand is why the amp stops responding to volume boost the higher I turn it up. At 1 on volume master on the amp, with 3db on the volume boost, it works fine. At 5 on the volume master, and 3db (or even 9db) on the volume boost, it doesn't increase the total volume. In both cases I am loading additional db into the power amp but the more I am pushing the power amp the less the total volume is increased by the volume boost. This seems to be the point that the dynamics of the amp are reduced as the volume goes up. Is there a solution to this? Do the volume boost switches that Mesa provide on some of their amps suffer the same problem or are they engineered differently please?

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All tube amps function like this. It's called headroom and once you run out of it the amp won't go any louder. Normally at that stage people would start suffering ear damage and turn the amp down slightly, but the attenuator is clouding your impression of the amp by allowing you to leave it up full and hear it in a less impressive state.

Once you run out of headroom you start overdriving the amp. Overdrive is a desirable characteristic in a tube amp. If the volume knob was designed to hit maximum volume with the knob at full we wouldn't be able to overdrive our amps and rock 'n roll would have no soul.

I'd consider backing your attenuator off a few clicks. If you're constantly running your amp full out into attenuation you're going to kill the life of your power tubes. It'll also force you to turn your amp down slightly, which will open up some headroom and allow your boost pedal to function again.

Now I understand what is going on. Shame I can't get the full overdriven tone and a solo boost I can live with the problem. If you want the tone and to hear your lead lines, then either you get a second amp, or you lose the second guitarist in the line up.

Or you get the other guitarist to lay back and let you stand out more.

What kind of music are you guys playing that you're maxing out your headroom? Also why not drop the attenuator when playing with your band or at least don't attenuate so much?