MXR M-81 Pedal Preamp

Dennis Detweiler · Post by **Dennis Detweiler** » 26 Oct 2023 8:40 pm

I've been experimenting with a few pedal preamps. I know about the Sesh400, but I've been trying a few that aren't intended for steel guitar. To date, I've found one that fits well and is under $200. The MXR M-81 is a bass pedal preamp. However, I compared its specs to the Session 400 and they are nearly identical.

Session 400 tone controls:
Bass= 45hz
Mid= adjustable mid frequencies
Treble= 2.7K hz (Nashville 400 is 6k hz)
Presence= 10k hz

MXR M81
Bass= 40hz
Mid= adjustable mid frequencies
Treble= 4k hz
No presence control (no need)

Review: I was able to dial in a clean tone setting for steel guitar that matches the Session 400. I have several power amps, but have only tried the M81 with a Carvin HT400 rack amp and with a Quilter 201 and 200. Equal results.

David Higginbotham · Post by **David Higginbotham** » 27 Oct 2023 7:08 am

Some bass amps in the past have been very good steel amps and your find is interesting. I’ve been wanting to try something different, affordable, and compact so this may fit the bill. Thanks for the info, Dennis!

Dave

Larry Dering · Post by **Larry Dering** » 27 Oct 2023 12:53 pm

I like those results. I need to find one.

Dennis Detweiler · Post by **Dennis Detweiler** » 27 Oct 2023 1:32 pm

I found a slight difference between the Carvin HT400 vs both Tone Blocks. No difference in tone, but the Tone Blocks created some hiss (white noise). I don't know why? However, not enough hiss to keep from using them live. Carvin was dead quiet.

David Higginbotham · Post by **David Higginbotham** » 27 Oct 2023 1:57 pm

but the Tone Blocks created some hiss (white noise). I don't know why?

Placing a preamp in combination with a combo amp preamp section is going to create extra input signal that will cause excess noise and overdrive, in most instances, as opposed going into strictly a power amp, such as the Carvin.

Dave

Dennis Detweiler · Post by **Dennis Detweiler** » 27 Oct 2023 8:33 pm

Thanks Dave, Makes sense. Would plugging into the effects return bypass the preamp and go directly to the power amp?

Larry Dering · Post by **Larry Dering** » 28 Oct 2023 12:19 pm

Dennis, yes it bypassed and goes to the power amp.

David Higginbotham · Post by **David Higginbotham** » 28 Oct 2023 1:39 pm

Dennis, I see Larry has your answer, which is good as I haven’t had the opportunity to use the Tone Block. I know on peavey amps you can use the “preamp in” and it will bypass the preamp section. Obviously, the tone block has the same capability with the effects loop.

BTW, I ordered the MXR M81 pedal so hopefully I’ll have the same experience as you did. If not, my son plays bass so it’ll go to him.

Dave

Dennis Detweiler · Post by **Dennis Detweiler** » 30 Oct 2023 8:45 pm

I plugged the M81 into the effects return jack on the Quilter 201 and it works great, no hiss. It functions as a 200w power amp with master volume.