Hey, it's been a while since I lurked on this forum. Been playing way too much to build. :icon_lol: Anywho, I built a Firefly amp some time ago which I use for my lapsteel. Sounds great with the break up through the 1x12 cab that I also built for it. What I'd like to do is add a small digital reverb circuit to the amp and be able remotely switch it on and off. I know, I know, the purists will have a field day with adding a digital circuit to an all tube amp. Besides that though, a couple of questions:
1.) Would there be any noise issues with putting the circuit right in the amp chassis?
2.) If the voltage of the caps are large enough, can I power the circuit with the heater from one of the tubes?
3.) To remotely turn the reverb on and off, I assume I'm going to need use 12V DPDT relays and use GEOFEX remote indicating bypass schem?
4.) Anyone have a PCB layout or perf layout of the relay bypass system? I'm not so good with schematics.
Thanks for any assistance.
'The mang.
No one? Surely someone's done this or thought about it.
Hmmm... perhaps no-one here has thought about it? You could try asking the same question over at AX84.com (http://www.ax84.com/bbs/index.php)? They're a very friendly bunch - much like here - and always happy to help.
if you use something like a belton brick you'll need 5V regulated for the brick, and at least about 9V for the op amps. If your heaters are using the 12.6VAC and not the 6.3VAC wiring, it may be possible to rectify and smooth to something the op amps could use, then regulate to 5V for the brick.. if they use 6.3VAC it is much closer to not being possible, but maybe you could if you use schottky rectifier, much capacitance, and low drop out regulator. and op amps that don't mind just 8V or worse.
You will probably have enough current as the whole thing would use much less than a single heater.
I'm sure I read a post a year or so ago where someone did this...
http://www.diystompboxes.com/smfforum/index.php?topic=92837.0
Rick, did you ever get this to work? I have the reverb circuit all done which uses a Belton brick. It includes a Voltage Regulator. I'm just trying to figure out how to add the circuit in line with the amp and power it. Also, to build a remote footswitch to turn it on and off. I'll check out those links in your other post and at AX84.
I added digital reverb to my Octal Fatness and to my old Gregory Mark X amp. They worked out great. However, they are not foot switchable as I did it. But these posts may still give you some ideas:
http://www.diystompboxes.com/smfforum/index.php?topic=97777.0
http://www.diystompboxes.com/smfforum/index.php?topic=77120.0
Paul, those are both great threads. Thanks. So I was right in thinking that I could basically put the circuit between the input and the first tube stage. Of course mine will attached to a relay switch so that I can remotely switch on and off with a foot switch. I'm even thinking of using a switching jack so that if the footswitch isn't plugged in, it will always stay on. I'll have to figure that one out. I should be able to power it off of one of the heaters, I just may have to switch out the voltage regulator. Based on your threads, it looks like I will have to make some sort of shielding for the reverb board. Ok, I'm beginning to get this hashed out.
Anyone have any links to a layout for the single simple remote relay switch? I have the schem from GEOFEX, but haven't done layouts. Even perf or stripboard would work. Thanks.
Quote from: blues_mang on January 22, 2013, 03:07:40 PM
Paul, those are both great threads. Thanks. So I was right in thinking that I could basically put the circuit between the input and the first tube stage. Of course mine will attached to a relay switch so that I can remotely switch on and off with a foot switch. I'm even thinking of using a switching jack so that if the footswitch isn't plugged in, it will always stay on. I'll have to figure that one out. I should be able to power it off of one of the heaters, I just may have to switch out the voltage regulator. Based on your threads, it looks like I will have to make some sort of shielding for the reverb board. Ok, I'm beginning to get this hashed out.
Cool, glad you got something out of that. The switched jack is not a bad idea. You probably can power it off of the heater supply - Firefly uses 6.3V and diode rectified voltage would be approximately 8.9V. Kinda close. In my case, I just used a little 12.6V RadioShack power transformer to power the thing because I wanted 9.5V
regulated power for it, so I needed the extra voltage to account for the voltage drop thru the LM317 voltage regulator.