Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Tiny_Daddy on September 17, 2011, 09:49:29 am

Title: Ampeg V4B re-issue tube chart
Post by: Tiny_Daddy on September 17, 2011, 09:49:29 am

This amp uses all 12AX7 and one 12AU7 as PI. Problem is, I don't know if this is correct because the tubes are not original. I cannot find a schematic or manual that matches this amp. Should the tube that drives the PI be a 12DW7?

Title: Re: Ampeg V4B re-issue tube chart
Post by: ThermionicEngine on September 17, 2011, 10:30:46 am

If your amp is a V4b reissue (V4H), The PI is a 12AU7.  They did not use the 12DW7 or the compactron tube, or the 7027 for that matter.  The only problem is they used 2 12AU7s, I just don't remember where they used the other one...  I suppose there is no schematic in the cabinet or chassis.  I got half the question answered, anyway...

Title: Re: Ampeg V4B re-issue tube chart
Post by: Bub on September 17, 2011, 02:31:16 pm

Hope this helps

Rob

Title: Re: Ampeg V4B re-issue tube chart
Post by: Tiny_Daddy on September 17, 2011, 03:16:55 pm

Thanks, that's the amp. The preamp tubes don't seem to be called out but they are likely both 12AX7.

Title: Re: Ampeg V4B re-issue tube chart
Post by: LooseChange on September 17, 2011, 03:18:13 pm

The chassis is labeled with all the tubes types.

Title: Re: Ampeg V4B re-issue tube chart
Post by: Tiny_Daddy on September 17, 2011, 03:50:53 pm

This chassis isn't, I went and looked again. No labels in the cabinet either. Anyone out there with a labeled chassis?

Title: Re: Ampeg V4B re-issue tube chart
Post by: jerrydyer on November 16, 2017, 03:44:43 pm

I havent been here in a while but , im fixing a v4b reissue. Check this out, correct voltages on heaters but tubes will not light up.
HELP
Thanks

Title: Re: Ampeg V4B re-issue tube chart
Post by: sluckey on November 16, 2017, 04:12:24 pm

Maybe you're not measuring the filament voltage correctly. Measure the voltage between the filament pins, not from chassis to one pin and then from chassis to the other pin. IOW, put one meter probe on one filament pin and the other probe on the other filament pin. I bet that will tell a different story.

Title: Re: Ampeg V4B re-issue tube chart
Post by: jerrydyer on November 21, 2017, 03:47:29 pm

Thank you sir.  Have you dealt with the,reissue,v4b, the one with blackface and colorful v4b.....blue and red?

Title: Re: Ampeg V4B re-issue tube chart
Post by: sluckey on November 21, 2017, 04:09:54 pm

no