1U Effect Rack With Relay Control

[chillhuman]

Other than that it's done. So trying to decide what's next. I kind of have my eyes set on those Weber tube amp kits, but will see. Although a 1U rack with all tube based effects would be nice 

BR,
Aleksi

You may want to check out www.ax84.com

They have a boat load of great amp projects. www.18watt.com also is for people wanting to build a Marshall 18W amp.

You will have to build a head enclosure for your head unit, but going this route you get to pick all the components that go into it. I built my current gigging amp that way and I absolutely love it.

[Aleksi]

Mike, that's a good question. Honestly I don't know why should use a transistor over a regular switch if just use it for switching the relay. Since I've been to school I've always just seen the "use a transistor to control a relay" everywhere. So R.G. (or someone else with experience with audio electronics) might give you a full explanation about the benefits of one over the other. But I would GUESS using the switch directly might cause pops/noise due to the relay / switch contacts bouncing. If you try it, please let us know how it sounds!

The reason why I used transistors, is that it gives me a bunch of other nice options for the future (as I'm getting these PCBs done properly) and also allowed me to add the option of "in-rack LEDs" by using the MOSFET gate voltage to turn on the LED. In the future it also allows me to use, for example, TTL level signals to control the relay which expands the possibilities if I want to use it with a micro controller.

I opted to use the BS170 MOSFET over a NPN transistor, because I have quite a few BS170s lying around But you can use a NPN transistor for switching also, and I think most examples on the internet are ones with a NPN transistor.

Your project indeed would call for some remote switching. My reason for using the relays was the same as yours. Running the signal wires several metres to the footswitch and back would have been a sure way of getting all the possible noise in the signal line.

Chris, the list of mods / options I did to the TS are

- front panel switches for a) gain boost, which adds a 470k resistor in series with gain pot b) bass boost, which allows to switch between the stock 47nF and 330nF cap in the clipping op amp section. This brings in more bass to the to distorted signal.
- front panel clipping rotary switch, allows me to choose the clipping method from a) symmetrical 1N4148 b) asymmetrical 1N4148 c) symmetrical LED and Ge diode d) symmetrical MOSFET e) symmetrical 1N4001 and Ge f) Clean boost, no clipping
- After the first op amp section (clipping) there is a low pass filter made with 1k/220nF. I switched the cap to 100nF which allows more highs in to the circuit. This made tone pot useful through out it's whole range. Now this is probably gear specific, I tuned the circuit for Strat.

Chill, thanks, I actually checked the ax84 project a few days back. But the 18watt website was new, will head there now! I currently have about ten websites open.... Weber, Ceritone, Mojo, Ampmaker etc. The Weber kits would be great for me as they would allow me to make a complete set with nice covers and so on. But the problem is that I really could use a master volume in those kits and that would cost extra money. Also the shipping and taxes increase the price. So right now looking at european alternatives, atleast for places that offer speaker cabines and amp cabinets for a reasonable price. The UK company Ampmaker has two nice kits and with the current cheap pound in respect to the euro I could really go for one of those! Will see.

BR,
-Aleksi

[cpnyc23]

Chris, the list of mods / options I did to the TS are

- front panel switches for a) gain boost, which adds a 470k resistor in series with gain pot b) bass boost, which allows to switch between the stock 47nF and 330nF cap in the clipping op amp section. This brings in more bass to the to distorted signal.
- front panel clipping rotary switch, allows me to choose the clipping method from a) symmetrical 1N4148 b) asymmetrical 1N4148 c) symmetrical LED and Ge diode d) symmetrical MOSFET e) symmetrical 1N4001 and Ge f) Clean boost, no clipping
- After the first op amp section (clipping) there is a low pass filter made with 1k/220nF. I switched the cap to 100nF which allows more highs in to the circuit. This made tone pot useful through out it's whole range. Now this is probably gear specific, I tuned the circuit for Strat.

Thanks!!
-chris

[cpnyc23]

Aleksi - another quick question for you...  Are you using the 5V relay?  I thought that all G5V-2 were volts (hence the name) but when I went to Mouser I discovered that there were higher voltages available...  If I see correctly, you are running this setup on 9V but I just wanted to make sure I'm not missing something.

Thanks again
-chris

[Aleksi]

Hi Chris,

sorry for the delay in reply, for some reason I didn't get a notification from this thread.

Yes there are several different voltages available for the Omron relays, check here http://www.omron.com/ecb/products/pry/111/g5v_2.html

I used the 12V relays and the system is actually running on 12V now (the regulator board has two 7812 regulators). The relay board probably has the "wrong" Vcc in the schematic as I used the +9V(T) to provide a Vcc with a pad in the layout.

Anyway, the voltage doesn't matter. The circuit should work just fine as long as the Vcc matches the relay's voltage rating. So you can use it with a 9V power supply with the 9V relays. The Omron relays should still work with 75% of the rated voltage, but your always better getting as close to the rated voltage as possible.

BR,
Aleksi

[zencafe]

Wow Looks Amazing!! Congratulation!!

Oikeasti, se on niin seksikäs  .

Regards

D.

[Aleksi]

Thanks 

[cpnyc23]

ahh!  I missed the regulators....  thanks for the post.

-chris

[Dizzy_G]

Hi Guys,

Firstly i would like to thank Aleksi for providing his layout and schematic to this unit, it is an excellent idea and implementation, good work.

Secondly i have offered to host his files for him, they are available here http://rapidshare.com/files/205266728/Aleksi_layout_schematic.rar on a premium acc so shouldn't get deleted.

Regards,
D_G

[gtrplaya101]

I would like to use this for something I'm building but I have two questions. 1) In that layout what happened to all the grounds? To me they appear to floating. 2) I have already built something similar but have been having some trouble with hum. Does this have any problems like this. 3) (ok so I lied haha) Can you use several of the boards tied together to control more loops? Thanks Curt

[Aleksi]

Hi Curt,

1) not sure what you mean by floating?
- The regulator board and the relay board have ground planes. Both boards are connected to the chassis with metal standoffs which connects the ground to the chassis.
- The relay board gets Vcc and GND from the regulator board
- Each effect gets Vcc and GND from the regulator board

=> all GNDs are tied together

The relay board only switches the in and out signals, not the ground.

2) No, I haven't had problems with humming. I do get some buzz when I connected the MOSFET booster, compressor and Tubescreamer all at high gain levels, but that's another thing. When I was building this I didn't even think about shielded wires etc.

3) yes you can use multiple boards together, as many as you like. Basically my board with four relays is similar to using four separate boards that would each have just one relay.

Hope that helps, if you have any more questions just fire away!

BR,
-Aleksi

[gtrplaya101]

Yeah I'm sorry if I am confusing you. Basically I am looking for something that I can etch. Cant really etch a ground plane. What layout did you use to etch yours? Thanks in advance!

[Aleksi]

Hi Curt,

Sure you can etch the GND plane. I used that exact layout for my boards (although I didn't etch them myself, because I don't have the equipment). Basically the difference between etching a "normal" board and one with a ground plane is, that instead of etching most of the copper away it stays on the board as a GND plane.

If you're using Eagle, than the GND plane is not normally visible in the layout, just the GND plane edges. You have to press "Ratsnest" to make it visible in the layout.

BR,
Aleksi

[gtrplaya101]

OHHHH I see it now!!! I'm not real familiar with Eagle so it all makes sense now! Your power board. Does is only regulate voltages or are you filtering them as well? I really want to make sure that I eliminate this hum problem. Also are those values set up for 18v or could I use a 9v source in its place.

[Aleksi]

Hi Curt,

The 18V and 9V symbols on the schematic are incorrect, I used those because they had pads available on the layout. I'm using about 15V (from a regular wall transformer) to feed the regulator board. It has two 12V regulators (LM7812). One for the effects and one for the relays. I used separate regulators, because I was worried that if I used just one then switching the relays might cause noise to be carried to the effects too. So the 18V on the layout is actually 15V and the 9V is actually 12V. You don't have to use 12V just as long you pick the relays according to the operating voltage. I used 12V relays with the 12V operating voltage.

You basically have to use filtering capacitors with regulators. So my setup has 15V in => filter caps => regulator => filter caps => 12V.

If you have a good 9V transformer than you can forget the regulator board and just use it to power the effects and the relays. Adding some filtering caps for the relay would be good too.

BR,
Aleksi

[gtrplaya101]

Ok so here is my plan:
I would like to rack mount all my pedal and use this to control them. The pedals will have their very own power supply from this controller. I will be using 1/4 jacks to connect them to the board. Can I also use a different 9v source to run this board or will that cause ground loops? My plan is to run 9v into a regulator board like yours for filtering etc. Then use a 5v regulator to drop it to the rated 5v relays. From there it will be just like your board. If I want to run 5v relays do I need to change any values of components on your board? Thanks

[Aleksi]

Hi Curt,

if you have a 9V source to feed the effects and the 5V regulators it should work just fine.

If you use the 5V and have the LEDs connected to the MOSFET gates, then you should probably drop the 4.7k (LED series resistors) to about 2.2k and also the 1k series resistor going to the switches to about 500ohms.

BR,
Aleksi

[mth5044]

Anyone have the updated schematics that were posted? Links dead!

[arma61]

Hi

you mean the 2 at the beginning of the thread ? here they are





Cheers
Armando