Hotswitch with footswitch

[TryingToDo613]

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Author  Comment  
no more guitar solos
Junior tube assistant
Posts: 72
(5/24/05 10:38 pm)
Reply  Hotswitch with footswitcch?
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 Has anyone tried this? Can it be done using a TRS cable to the footswitch?
I'd like to try the Hotswitch, but unless I can do it with my foot it's of little practical value. If anyone has done it I'd love to hear about it.
Thanks
-dave

 
mrr3000gt
I only work on Fender's
Posts: 582
(5/25/05 12:10 am)
Reply  Hot switch-a-roo
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 This post pops up once in a while.

With the hotswitch, it IS possible to rig up a foot switch mechanism of some type (and it is also possible to have it quiet). The problem is that the level difference between the two will be mostely unusable if you want to try to use it as a 'two channel' amp.

Think of the hot switch as a 'mode switch' for the amp. You can assign the operational mode of the amp to be higher or lower gain.

All a foot switch will do is save you the trouble of flipping the switch. You still have to adjust the controls after a switch. Also, the hassel of fabricating a switch mechanism and making it work quietly is an added bonus.

There are some who have dont it, but again, the volume difference thing makes it (in my opinoin) unusable as a channel switcher.
 
ampcabinets
Senior tube assistant
Posts: 156
(5/25/05 1:38 am)
Reply
  Re: Hot switch-a-roo
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 This was addressed in several recent earlier posts. Including one, when I asked the same question. There were several very good replies and ways to do this.

you can try webers channel switch as well.

rob
 
zachsdad
Senior tube assistant
Posts: 179
(5/25/05 6:07 am)
Reply  Re: Hot switch-a-roo
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 Go to the website below and look at this diagram. It is an earlier version of an amp I built for my son. Notice the "Boost Relay" in the upper left corner and the "Boost Footswitch and Relay Coil" in the lower right. This switches an extra gain stage in and out. The reason I used a relay was so the signal would not have to travel the long length of wire to the foot switch, only thru the relay on the turret board. I used a relay with a 5 VDC coil so I could use the 6.3 V heater winding for the power for the relay. I had to increase the 47ufd filter cap at the relay coil to 4700ufd to get rid of the hum. The extra gain stage has its own volume control so he sets it for his solos. I has a nice distortion when it is kicked in, and relatively clean when it is out.

Be glad to answer any questions you might have. He is really pleased with the amp.

Leslie

img.photobucket.com/album...TR2523.gif



You will also notice that the boost stage has its own volume contol and can be preset. No interaction when boost is off.
LG


Edited by: zachsdad at: 5/25/05 2:39 pm
 
Voxbox
Senior tube assistant
Posts: 170
(5/25/05 8:13 am)
Reply  Re: Hot switch-a-roo
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 Can you check the link please? It doesnt work for me.
Thanks
 
zachsdad
Senior tube assistant
Posts: 181
(5/25/05 2:40 pm)
Reply  Re: Hot switch-a-roo
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 Link should work now.
Les
 
PHATamps
I only work on tube amps
Posts: 484
(5/25/05 5:31 pm)
Reply  Re: Hotswitch with footswitcch?
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 www.phatamps.com/pages/5/index.htm
 
no more guitar solos
Junior tube assistant
Posts: 73
(5/26/05 8:34 pm)
Reply  Re: Hot switch-a-roo
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 Thanks for all the suggestions, guys.
But I'd really like to avoid the added complications of a relay. Has anyone just done it from the footswitch? If so, I'd love to hear how you wired it.
Thanks
-dave


 
zachsdad
Senior tube assistant
Posts: 184
(5/26/05 9:09 pm)
Reply  Re: Hot switch-a-roo
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 no reason it can't be done, but youre asking for trouble sending the signal outside the chassis when its not necessary.

My nickels worth
 
TryingToDo613
Junior tube assistant
Posts: 84
(5/26/05 9:41 pm)
Reply  Re: Hot switch-a-roo
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 PHAT and Les. Could you possible post your switch logic. I've looked at both schematics and can't figure it out.

For those who don't know what I'm talking about, a DPDT relay has 8 pins

1 2
3 4
5 6

7 8


Pins 7 and 8 are the "coil". You run a charge through there that you turn on and off, with a footswitch, regular switch, etc. When the charge is on, a magnet swings two pole pieces one way and when the charge is off the pole pieces swing the other way, that way being the default.

Pin 5 is where you connect the signal coming in. Pin 6 is where you connect the signal going out. When the switch is off your signal routes out through pin 1 and back in through pin 2 (so 1 is connected to 5 and 2 is connected to 6). When the switch is on, when you send electricity through the coil and it flips the magnet, the signal goes out through 3 and back in through 4 (so 3 is now connected to 5 and 4 to 6).

So for a true bypass thing (or leaving a circuit in standard configuration in this case) you would just jumper accross 1 and two. The relay ideally has no resistance so it wouldn't effect your circuit at all. When you flip the switch or hit your footpedal the signal is routed through your alternate path.

Could you guys how your paths work, how you are feeding the grids and how you switch the signal on the other side of the tube as well? I have stared at both and can't figure it out. -613

Edited by: TryingToDo613 at: 5/27/05 1:05 pm
 
no more guitar solos
Junior tube assistant
Posts: 74
(5/27/05 8:27 pm)
Reply  Re: Hot switch-a-roo
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 Zachsdad wrote:
"no reason it can't be done, but youre asking for trouble sending the signal outside the chassis when its not necessary."

I've been using a tone circuit ground lift controlled by a footswitch on the end on a 20 ft cord for a while with another amp without any problems.
Is what we're talking about here a different deal? What are the issues that you are concerned about?
Thanks
-dave

 
zachsdad
Senior tube assistant
Posts: 185
(5/28/05 7:53 am)
Reply  Re: Hot switch-a-roo
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 613,

Unless you want control of the boost circuit you can eliminate what I call the "Boost Switch". For now I will assume you dont need this. It makes explanation easier.


Look at the diagram on this link:

img.photobucket.com/album...ircuit.gif

With the relay contacts in the "down" position, the output from V1a, the first stage is routed to the input of V1b, the "Boost Stage" through the Boost Volume control. (Notice that this can be preset and will not interact with the tone when the boost stage is out of circuit.) The output of the Boost Stage is also routed to the input of the tone stack and on the the next stage.

With the relay contacts in the "up" position, the output of V1a is routed through both sets of contacts directly to the input of the tone stack, bypassing the boost stage.

Hope this helps.



No More Solos,

With my understanding of the ground lift circuit, you simply use a switch to effectively insert a resistor/capacitor circuit in the ground path of the tone stack. The audio signal to the next stage is not going out of the chassis and its chances of picking up stray noise or incurring losses is minimal.

Leslie

Edited by: zachsdad at: 5/28/05 8:01 am
 
TryingToDo613
Junior tube assistant
Posts: 86
(5/28/05 9:26 pm)
Reply  Not so complicated
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 Thanks Leslie. Yea, that's how I thought it worked. I just couldn't see that in that schematic. I'm going to try to go print it on a printer and see if I can trace things out with a marker. I don't know what the numbers go to, the gain pot? I hate to be a pest. -613
 
zachsdad
Senior tube assistant
Posts: 186
(5/28/05 11:26 pm)
Reply  Re: Not so complicated
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 Those are just pin numbers for the particular relay that I used. They wont mean much to anyone else. I should have removed them all.

 
TryingToDo613
Junior tube assistant
Posts: 88
(5/29/05 5:06 pm)
Reply  Ok, like this it's complicated.
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 Aha. So that was the next phase of my questions. How do you work it so you can turn on and off from the panel when you are not using a footswitch. I will stare some more. I'm assuming what I see in the schem is a DPDT switch on the panel and a DPDT relay controlled by the pedal. I'm going to wire this up tonight maybe (we're in the middle of a move) and see how it works. Thanks Leslie. -613
 
zachsdad
Senior tube assistant
Posts: 187
(5/29/05 7:55 pm)
Reply  Re: Ok, like this it's complicated.
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 you assume correctly. They are wired to operate just like 3 way switches you might find at the top and bottom of a set of stairs. You will always have control, footswitch or no.