Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: shooter on October 30, 2016, 07:40:21 pm

Title: 1 knob TS
Post by: shooter on October 30, 2016, 07:40:21 pm

Looked for 1 knob TS, found this;

http://el34world.com/Forum/index.php?topic=9162.msg82661#msg82661 (http://el34world.com/Forum/index.php?topic=9162.msg82661#msg82661)

looked at (well drawn) schematic in reply 4;

Am I correct in assuming there is NO “junction” inside the circled area?

Thanks

Title: Re: 1 knob TS
Post by: John on October 30, 2016, 07:48:54 pm

Ordinarily, I'd think not. However, if there's no junction then what is that .01 connected to? IOW, what is it's purpose?

Title: Re: 1 knob TS
Post by: sluckey on October 30, 2016, 08:13:54 pm

I believe there is a junction.

Title: Re: 1 knob TS
Post by: shooter on October 30, 2016, 08:36:59 pm

so CX becomes a cathode bypass?  does the .01 then become like NF for a freq range?

Title: Re: 1 knob TS
Post by: VMS on October 30, 2016, 08:45:46 pm

I think this works so that when you turn the tone the .01 cap becomes bypass cap.


So this tone would be much more effective without the Cx cap.

Title: Re: 1 knob TS
Post by: VMS on October 30, 2016, 09:20:14 pm

Some magnatone amps use this same tone control.


http://el34world.com/charts/Schematics/files/magnatone/magnatone_410rd.pdf (http://el34world.com/charts/Schematics/files/magnatone/magnatone_410rd.pdf)


In this schematic you can see that when the tone is at zero the .001 cap is connected to ground and it dumps the high frequencies and when the tone is full you get a treble boost with the smaller than usual cathode bypass cap.

Title: Re: 1 knob TS
Post by: PRR on October 30, 2016, 10:30:03 pm

Well-drawn, serious hacker, but I suspect a transposition error.

> the .01 cap becomes bypass cap. So this tone would be much more effective without the Cx cap.

And just 0.01 on a cathode would do little.

Dot the circle. Put the 0.68 where the 0.01 is. Put the 0.01 back in the drawers. See if that gives clear 2-way action. But I suspect much of the action is in the last wee bit of a turn.

Title: Re: 1 knob TS
Post by: shooter on October 31, 2016, 08:35:26 am

Quote

But I suspect much of the action is in the last wee bit of a turn.

That's what I want to avoid, I'm still pencil-whippin my build, just hunting for a 1 knob solution, if possible.  Thanks for the insight.

dave

Title: Re: 1 knob TS
Post by: kagliostro on October 31, 2016, 01:26:26 pm

Ciao Dave

Have you seen this ? (look to the links)

http://electronicdesign.com/analog/simple-circuit-offers-single-adjustment-tone-control (http://electronicdesign.com/analog/simple-circuit-offers-single-adjustment-tone-control)

(http://electronicdesign.com/site-files/electronicdesign.com/files/archive/electronicdesign.com/content/content/64609/64609-fig1.jpg)

(http://electronicdesign.com/site-files/electronicdesign.com/files/archive/electronicdesign.com/content/content/64609/64609-fig2.jpg)

--

http://electronbunker.ca/eb/TubeAudio_01a.html (http://electronbunker.ca/eb/TubeAudio_01a.html)

(http://electronbunker.ca/eb/TubeAudio_01a_files/ToneControl_2.jpg)

--

http://monster.partyhat.co/article/amplifier-tone-stacks/#Moonlight (http://monster.partyhat.co/article/amplifier-tone-stacks/#Moonlight)

http://monster.partyhat.co/article/amplifier-tone-stacks/#one-knob-tone-controls (http://monster.partyhat.co/article/amplifier-tone-stacks/#one-knob-tone-controls)

--

(http://s20.postimg.org/xpit22dxp/U_65rn_tone_control.jpg)

--

http://mhuss.com/18watt/schematics/ (http://mhuss.com/18watt/schematics/)

(http://mhuss.com/18watt/schematics/ToneControl_PageSupro.gif)

(http://mhuss.com/18watt/schematics/ToneControl_Princeton5F2-A.gif)

(http://mhuss.com/18watt/schematics/ToneControl_Spitfire.gif)



Franco

Title: Re: 1 knob TS
Post by: tubeswell on October 31, 2016, 01:47:58 pm

Out of all of them, I still like the Tweed Princeton tone control the best. Mind you the Big-Muff tilt control can be made to be fairly dynamic, (although it is somewhat lossier than the TP)

Title: Re: 1 knob TS
Post by: shooter on October 31, 2016, 02:07:05 pm

Quote

Tweed Princeton tone control the best. Mind you the Big-Muff tilt control can be made to be fairly dynamic

Those are both on the short list.  but the tilt control I've seen adds a 2nd knob which I already have n want to eliminate.

Thanks Franco, the graphs are about what I'm getting with the BigMuff.

Most 1 knob'ers are integrated with a volume pot, can I assume it's NOT integral to the TS?

Title: Re: 1 knob TS
Post by: tubeswell on October 31, 2016, 02:18:02 pm

Quote from: shooter on October 31, 2016, 02:07:05 pm

Most 1 knob'ers are integrated with a volume pot, can I assume it's NOT integral to the TS?

Depends on how they relate to each other.


If the vol and tone controls are separated by another gain stage, then less so - although either vol or tone controls each can shape the frequency shelving to some extent on their own (remembering that the resistance between the vol pot's input and its wiper interacts with the miller capacitance of the following stage when the pot is dialled down, but this can be overcome with a 'bright' bypass cap).


But if the vol and tone controls are part of the same AC load on the previous stage, then interaction can't be helped.

Title: Re: 1 knob TS
Post by: shooter on October 31, 2016, 02:51:59 pm

Quote

If the vol and tone controls are separated by another gain stage, then less so

Thanks, that helps, I'm using mostly fixed R voltage dividers, (gain control), 'tween stages.