Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Silvertone on August 16, 2018, 03:02:39 pm

Title: Bogen CHB 10A's Come alive
Post by: Silvertone on August 16, 2018, 03:02:39 pm
(http://i66.tinypic.com/2z74rbc.jpg)
Title: Re: Bogen CHB 10A's Come alive
Post by: jjasilli on August 16, 2018, 04:58:06 pm
 :thumbsup:
Title: Re: Bogen CHB 10A's Come alive
Post by: Platefire on August 28, 2018, 08:48:45 pm
That's what I call CHB10A Heaven with those nice colors and cabs. Fine work there!

Here is my less dressed CHB-10A
Title: Re: Bogen CHB 10A's Come alive
Post by: moapys on November 13, 2022, 08:24:13 am
Old thread resurrection / cross-post alert! Say friends; on this odd Bogen CH10 power supply: I've never seen the filter-cap arrangement as seen on the first stage before (attached)...? In all PS that I've seen, all caps are referenced to ground (e.g. B+ on pos / GND on neg); yet this one has a "stacked" initial R/C filter, with one element of the original can multi-cap in series with an external electrolytic of the same value!

I've just recapped one, to begin a guitar conversion, but - before I bring it up on the variac - was hoping someone could help me understand the intent of injecting the rectified DC BETWEEN a pair of 20uF's (C1 and C2 on the PS schematic). Thanks in advance!
Title: Re: Bogen CHB 10A's Come alive
Post by: thetragichero on November 13, 2022, 09:16:00 am
Quote from: moapys on November 13, 2022, 08:24:13 am
on this odd Bogen CH10 power supply: I've never seen the filter-cap arrangement as seen on the first stage before (attached)...?

read up on voltage doubler circuits. non-center-tapped ht winding with too low vac for a full wave bridge to provide desired dc voltage so bogen uses a voltage doubler (I've used a voltage tripler/quadrupler on an old organ transformer to get bias voltage before. definitely a good trick to have in the arsenal)
Title: Re: Bogen CHB 10A's Come alive
Post by: PRR on November 13, 2022, 03:34:49 pm
Cross-posted and answered at
https://www.diyaudio.com/community/threads/bogen-chb-10a-conversion-need-help-and-advice.83746/post-7173872
??


Title: Re: Bogen CHB 10A's Come alive
Post by: moapys on November 13, 2022, 04:57:30 pm
Should have re-drawn to recognize topology - 'multipliers are familiar...apparently undercaffeinated. 
Amp came up just fine; only some hum/noise to remediate, and a dodgy preamp socket that needs a clean and tighten.  Thx, all.