Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TIMBO on August 01, 2013, 04:23:04 am

Title: 125C1A Choke
Post by: TIMBO on August 01, 2013, 04:23:04 am

Hi guys, Got one of these and trying to decide whether to use it or not but first, its rated @ 90mAs and can be used for Bassmans but the build I am doing is basically the same as a bassman but with three more preamp tubes. I'm thinking that having a choke can only help with this build but is this choke rated high enough for the extra preamp tubes or is there more math to it.

I have put a socket in for a rect tube but at this stage I will use a SS plug and my thoughts were not to use a choke and put in a resistor to give a bit of SAG. Thoughts  :think1: Thanks

Title: Re: 125C1A Choke
Post by: tubeswell on August 01, 2013, 04:42:41 am

Yeah that'll be fine. Each pre-amp tube stage draws about 2mA max from the HT supply if its a 12AX7, a little more for a 12AT7

Title: Re: 125C1A Choke
Post by: TIMBO on August 01, 2013, 02:19:18 pm

Thanks tubeswell, While we are on the subject, I noticed that in the Hywatts they have a choke/resistor combo, is this to simulate  SAG when using a SS rect????

Title: Re: 125C1A Choke
Post by: TIMBO on August 02, 2013, 03:36:24 pm

This is what I am working on. I have a socket for a rect tube but the only rect tube I have on hand is a 5U4GB and as my PT is already a bit under powered (300-0-300) would be better if it was 325-0-325 at the moment a SS rect will lift the juice a bit. A GZ34 would be better for a bit of sag. This i'll will try later in the build to see what it will do. So i'll try the 100r/5w resistor after the choke as Hywatt does. Thanks

Title: Re: 125C1A Choke
Post by: tubeswell on August 02, 2013, 09:48:55 pm

Quote from: TIMBO on August 01, 2013, 02:19:18 pm

Thanks tubeswell, While we are on the subject, I noticed that in the Hywatts they have a choke/resistor combo, is this to simulate  SAG when using a SS rect????

Which Hywatt schematic are you referring to?  http://hiwatt.org/tech2.html (http://hiwatt.org/tech2.html)

Title: Re: 125C1A Choke
Post by: TIMBO on August 03, 2013, 12:12:47 am

 :w2: Hi tubeswell,  :think1: Looking at the Hywatt schems and  :w2:. I did a build of the Jimmy Page and used M Huss's schems and now that I have had another look there is NO choke in the PSU  :w2: so I've got no idea where I got that from  :w2: so i'll just put the choke in and be done with it. Thanks

Title: Re: 125C1A Choke
Post by: kagliostro on August 03, 2013, 06:34:45 am

Quote

I noticed that in the Hywatts they have a choke/resistor combo, is this to simulate  SAG when using a SS rect????

May be you remembered this schematics ?

K