Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on May 14, 2012, 06:08:12 pm

Title: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: kagliostro on May 14, 2012, 06:08:12 pm

Some time ago I got an old Davoli Band 4 amp

there is a SS preamp (a very small reverb tank is present) with 4 inputs and a tube PA

only today I was able to get the schematic of the preamp and I'm confused

is this a guitar amp ? I doubt

looking to the input I'm not able to understand if this can be used as is as to amplify a guitar

the fact that it has a SS circuit (I understand near nothing about SS), the tone control at the input and the fact that input is rated at 30-800ohm confuse me a lot

please can you give me help ?

Thanks in advance

Kagliostro

Title: Re: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: sluckey on May 14, 2012, 06:48:51 pm

It looks like a 4 input Low Z microphone mixer with reverb.

Title: Re: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: birt on May 15, 2012, 03:34:40 am

since the input is already solid state there is a big chance the 'modern' mics at that time were already mostly low impedance. this suggests you have mic inputs there. there were lots of small mixers that had a tiny reverb tank, in most i've seen the reverb was on all channels. it's called 'band' and has a PA in the same unit. so its probably made to amplify a band without too much extra gear. 4 mics was plenty (the Beatles could do it). Set the levels, rock the local club.

Title: Re: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: kagliostro on May 15, 2012, 08:14:51 am

Thanks Sluckey & Birt

I'm not sure about what to do

may be I change the preamp and I'll obtain a guitar amp

I don't think I can use this preamp with some mod as a guitar preamp

Kagliostro

Title: Re: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: birt on May 15, 2012, 11:08:20 am

it looks like the impedance is set by the resistor values in the passive network of a single channel before it gets mixed. so if you play around with these values (make them higher go to 1M pots and get the fixed resistor values in the same ballpark. i'm sure someone can calculate all this but i'm not that someone. i just try things) you can make it suitable for guitar. or replace those passive networks with something like the ROG fetzer valve. that will probably give you a nice bit of gain on tap and you can still use the reverb. ( http://www.runoffgroove.com/fetzervalve.html (http://www.runoffgroove.com/fetzervalve.html) )

Title: Re: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: kagliostro on May 15, 2012, 12:43:21 pm

Thanks Birt

for your councils and for the Fetzer link, I didn't know that

Kagliostro

Title: Re: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: kagliostro on May 15, 2012, 03:08:58 pm

Quote

Just curious, Is this thread going to be moved to the SS section?

May be, the amp is a tube amp, but the preamp is SS

Kagliostro

Title: Re: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: kagliostro on May 17, 2012, 08:13:42 am

No I haven't considered any mod to the PA

I'm interested only to mod the preamp as to use the amp with guitar instead of microphones

may be I decide to clone the preamp of the Davoli Show II or, may be, to build a tube preamp

Kagliostro

Title: Re: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: PRR on May 17, 2012, 11:58:19 pm

You want just one guitar input, correct?

Title: Re: Old 1967 Davoli Band 4 italian amp - Which amp is this ?
Post by: kagliostro on May 18, 2012, 03:38:51 am

Quote

You want just one guitar input, correct?

Yes that I want !

Many Thanks PRR

Kagliostro