Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on December 23, 2011, 02:26:20 pm

Title: Champ used to create effects - Who was to do it ?? I don't remember
Post by: kagliostro on December 23, 2011, 02:26:20 pm

I have an amnesia

time ago there was a discussion about the use of a champ circuit as an effect

there was a load resistor connected instead of a speaker and the signal was send to another amp

Please I don't remember who do that and also would like to see the original schematic that was posted

Thanks

Kagliostro

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: Willabe on December 23, 2011, 02:42:49 pm

Garnet Gillies maker of Garnet amps made an amp called the Herzog. I think that's what your talking about.

There's a site on the net about his amps, with schematics.


         Brad      :icon_biggrin:

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: chocopower on December 23, 2011, 02:48:39 pm

here is.

http://www.aronnelson.com/gallery/main.php/v/Caseys-Vintage-Effect-Page/album27/Garnet_Herzog.jpg.html (http://www.aronnelson.com/gallery/main.php/v/Caseys-Vintage-Effect-Page/album27/Garnet_Herzog.jpg.html)

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: kagliostro on December 23, 2011, 02:51:23 pm

MANY THANKS

That is !  :smiley:

Kagliostro

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: stingray_65 on December 23, 2011, 10:59:16 pm

Check out Ted Webers little transformer.

https://taweber.powweb.com/store/balun.jpg

It is a low watt 150 ohm : 150 ohm transformer that is great for tapping off the speaker side of an amp.

If I were to build such a thing (hertzog), I would replace the 6 r 10W dummy load with a speaker motor and use Webers little transformer.

I think the purely resistive dummy load would affect the tone greatly.

If one tried, I bet this could be built into a very small box

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: kagliostro on December 24, 2011, 03:55:24 am

Hi Stingray

I'm not going to build such a thing, the info was for a friend that is building something similar

don't know the impact that can have the use of a speaker motor and a transformer in place of the resistor, but anyway that is a good info, I've never considered such a thing

Thanks for the input

Kagliostro

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: jeff on December 24, 2011, 02:18:19 pm

Wow! I was just thinking of doing the same thing!

I was going to use just a 4 ohm resistor, any reason to use a 6 ohm? Maybe it's close enough and it's what the builder had avalible???

The one I'm building will have a switch for EL84 or 6V6 by paralleling the sockets(except for the cathodes) with a switch to ground one or the others cathode resistor. Also a switching speaker jack that disconnects the 4 ohm resistor so it could be used as an amp or an effect.

 I was thinking of using a DPDT center off switch. One pole would be AC the other would connect the cathode to ground so it would be 6V6-OFF-EL84. This way you'd be turning it off when you are switching power tubes.

Is it OK to use a DPDT switch with AC on one pole and the powert tube's cathode on the other?

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: jeff on December 25, 2011, 01:28:34 pm

I was thinking maybe a pure resistive load could be good in this situation. If the reactive load changes with frequencies and has more/less gain at different frequencies and you're using this for a preamp, then it will be double EQ(The reactive load of the preamp tube changing with frequency, then the reactive load of the amp you're driving changing with frequency). In other words the frequencies accented by the power amp will also be accented by the preamp doubling the effect.

Using a reactive load for an attenuator, I get it, but maybe not so bad to use a purely resistive load in this case if it's used as a preamp.

Just a thought.

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: kagliostro on December 28, 2011, 12:07:56 pm

Stupid question due at my low knowledge

what will happen

if instead to use an OT and than a resistor as load in the secondaries

we use only a resistor to load the final tube/tubes and take the signal from there ?

I know this is a crazy question but it come to me  :think1:

Kagliostro

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: jeff on December 28, 2011, 05:08:22 pm

I don't know. A while ago I had the same idea but never tried it or got any feedback on it.

If you had a 6V6 running at 250V plate and screen at 48mA with a 5K:4 ohm transformer hooked to a 4ohm load would that be the same as using a 5K resistor as a load?

 You'd have to increase the plate supply when using the resistor as a load instead of the transformer to 490V because the 5K resistor would drop 240V @ 48mA whereas the transformer wouldn't. I was thinking of using a voltage doubler and taking the screen and preamp B+ off the botton cap.

 Aside from the fact you're taking the output from the plate rather than from the 4 ohm loaded secondary, wouldn't the load line be the same and the tube be acting exactally the same?

Something like this? would it work?

Title: Re: Champ used to create effects - Who was to do it ?? I don't remember
Post by: HotBluePlates on December 28, 2011, 06:24:16 pm

Quote from: kagliostro on December 28, 2011, 12:07:56 pm

what will happen

if instead to use an OT and than a resistor as load in the secondaries

we use only a resistor to load the final tube/tubes and take the signal from there ?

Gar Gillies and Randy Bachman didn't care if the resistor load didn't sound like a speaker, because the padded output was then plugged into the input jack of another tube amp as, essentially, an effect pedal!

So the thing distorted, and speaker response was still being afforded by the final amp's speakers.