Davis 106 Amps

[plexi50]

I got a pair of Davis 106 mono block tube amps this afternoon. They are in minty condition. I have heard harp players love these little amps. I had a customer 3 or so years ago bring me one to recap. I didnt think i would ever find 2 of them for myself. Pure luck today. Does anyone have any opinions about these amps or there tone quality? I have not plugged them in or had time to go through them yet. The pic below is just a representation of the ones i have

Not sure if the schematic i have shown is like mine. Even though it says Davis 106, the schematic is dated 1973. I know these amps are early 1960 so theres a descrepency some where

[HotBluePlates]

Pretty cool little amp.

Any input other than the Mic input will be pretty neutered for guitar-use, with only one gain stage. Mic input at least has a volume control between 2 6EU7 (re-pinned 12AX7) stages.

Don't know if you'll like the tone control, but it should work about like a tweed Princeton.

The self-split push-pull output is a little funky, and you won't get full output power from the pair of EL84's, but you'll get close enough. Does save you and extra tube and power supply components for a phase inverter.

[Stankfut]

It looks cool!

[PRR]

82K next to "Tone" pot seems dubious.

Mic input is fine for guitar. Phono input will take iPod (use two 1K to mix left and right).

"Low Z" input is a very dubious hack. If you want bass you want more like 10uFd here. It is not balanced. Serious low-Z mike work wants a transformer. There's a $19 XLR-1/4" transformer at RadioShack.

This amp may well have run from late 1950s into the 1970s with very few changes. It's a no-frills supermarket amp, Musak input and voice.

[phsyconoodler]

I have one and love the little bugger!

[plexi50]

I have one and love the little bugger!

Did you make any changes to the preamp in that little bugger or keep it original?
I dont know what to do with them other than to check the bias and put them in the closet

[Satchmoeddie]

The low Z input was often tied into a telephone patch. That 90 volt ringer really cooked those poor little 420 ohm cathode resistors. Too cheap to buy external telephone bell ringers? Just tie the phoneline right into that low Z input & put a switch on it.  Scare the **** outa them shoppers! "Rain drops keep falling on my ZZZT ZZZT ZZZT!!" 

[Lectroid]

Never seen this one before, but I was really intrigued by how that "self-split" phase inversion happens.  I found it in RDH4, p. 585; they call it "screen resistance coupling."

I never realized before that the screen current varies with the signal, but I guess it must work.  It looks to me like the screen "output" (?) of one 6BQ5 is taken as the grid signal of the other 6BQ5, after dropping it by a factor of 1000...(?)  Is that right? 

RDH:  "All such methods ... have inherently high distortion."   HBP:  "... a little funky..."

Explains why so many old PA systems sounded like someone gargling marbles.  I believe they live on today, hiding inside  the amps that supply us with "music" while we're on hold...