Bogen DB 114 conversion

[Teleman55]

I have been looking for a simple amp to either build or rebuild as a learning tool,and realised that this amp was in a stash given to me a while ago.I plugged it in and it fired up.The sound is a bit muddy,not very loud and barely beaks up at full volume.It is a one channel PA with a selector switch(Aux,radio,RIAA,etc) Bass,Treble and volume-The tubes are EZ81 rectifier,2/6V6,one 7199 and one 12ax7.One thing that suprised me was as I played through it I pulled the 12ax and nothing changed,and the tone controls still work.So I am looking for some ideas for conversion to a guitar amp.Should I keep the EX81,what about the 7199? should I replace it with a 12ax? Does anyone have a schematic available?.

[Regis]

Sounds like the 7199 is the phase inverter and the 12ax7 is the preamp tube.

I would try to wire up a Fender style input jack with a 33k/1meg resistor setup to pin two or seven, or whichever one comes from the selector switch, on the 12ax7 and see what happens. Bypass all that RIAA shit and if it works then fool with the tone controls, then go forward with the power amp if need be, which is probably cathode biased. Amps like this can be more or less converted to tweed deluxes or the like.

Schematics for old Bogens are hard as hens teeth to find, good luck.

[Magnatone1960]

It is a one channel PA

I've got one of these amps and I wish it was a PA amp because it would be more suited for a conversion to a guitar amp. It's a hi-fi designed amp and the tone circuits and signal path is designed for that application. Not much high end available when plugging your guitar in. Easy enough to modify though if I didn't have so many other projects piling up.
You should be able to get a lot of volume out of yours assuming the tubes aren't shot. I suspect you may just be using the wrong input. Make sure you're using the magnetic phono input to connect your guitar. The other inputs are looking for a higher level input signal. There is also a DB attenuator switch on the front panel labeled "Loudness" which should be switched to zero for most gain. Max the treble control and adjust the bass for fullness. The one that I have has plenty of volume and breaks up early enough but has that "wet blanket" over the speaker sound compared to an amp designed more towards guitar usage.