Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: LooseChange on September 22, 2011, 05:01:48 pm

Title: Magnatone/Estey M-15 Schematic ??
Post by: LooseChange on September 22, 2011, 05:01:48 pm

I have one of these on my bench and I can't seem to find a schematic.
It's also called the Dual Imperial
And it's not the M-15A.

What a wild sounding amp!!! Stereo and all.

Thanks!

Title: Re: Magnatone/Estey M-15 Schematic ??
Post by: sluckey on September 22, 2011, 05:11:57 pm

See if this fits...

Title: Re: Magnatone/Estey M-15 Schematic ??
Post by: LooseChange on September 22, 2011, 06:52:14 pm

Thanks... I think that's it.
This amp fills the room  with luscious reverb slathered vibrato!
Very cool.

Title: Re: Magnatone/Estey M-15 Schematic ??
Post by: Mars-Hall on September 25, 2011, 12:28:01 am

I have the M-15A Imperial, it's the model with the 3x8" speakers.  It's next in the lineup for my bench.  I have 3 brand new Weber speaker ready to drop in, somewhere down the line, the originals were replaced with RS Realistic's that were widely mismatched impedance wise.  I've always heard good things about the vibrato but haven't had the pleasure, as of yet. 

I just ordered the 40/40/30/30uf @ 450v cap can from http://www.fliptops.net/index.htm (http://www.fliptops.net/index.htm) 

Here's a good source of info on these amps.    http://launch.groups.yahoo.com/group/Magnatone-Valco/ (http://launch.groups.yahoo.com/group/Magnatone-Valco/)

Title: Re: Magnatone/Estey M-15 Schematic ??
Post by: LooseChange on September 25, 2011, 05:56:33 am

Thanks Mars-Hall.
The M-15 is a bit different than the M-15A. The 15 has 2x8 speakers and two small tweeters.
If the 15A has the same vibrato, you will love it.

Title: Re: Magnatone/Estey M-15 Schematic ??
Post by: terminalgs on September 26, 2011, 10:44:11 am

The M15 has a stereo pair of 7189A’s and output transformers (like the M14)  but it adds a third output transformer  that operates in push pull fashion with a pair of 6GW8 power tubes to drive a dedicated 5” speaker.  This extra output channel was dedicated for reverb!   That M15 has 3 5" speakers.   Its almost like an M14+reverb (but the M14 has 2x8" speakers).

The M15A has its own special reverb circuit that is unlike the reverb in the M13, or the M10/M10A.  The M15A has a reverb tank driven by a tap on the speaker output  with a  tube recovery section, along with depth, tone, and echo controls all for the reverb section.  I believe the echo control actually varies the volume using an LDR.