Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Solid State => Topic started by: rzenc on June 21, 2009, 01:23:07 pm
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Hi folks...
I'm planning to build a 2 channel amp for the first time - I mean, completely independent channels, each one with it's on tubes..no switching here...however I need to switch between both channels at the input of the FX loop...until here it is ok, the relay Mr. Hoffman sells with withstand the endurance and provide quality switching since it does no show any kind of engaging/desengaging noise :wink:
But I will also need to use relays to switch in/out boost sections, for instance:
Channel 1 is based on *umbles/fenders + plus the boost section from him also..which I have modded to my taste. ok I already did the switching and it worked flawlessly :smiley:
Channel 2 is based on marshall plexi, and also the hot switch Mr. Hoffman employs. ok already did the switching and it worked flawlessly :smiley:
So, up to now the relays worked nice, no noise at all...but all them were just a simple stuff inside one amp...now I need to find a way to supply the necessary voltages to all the relays, so that I could operate from one power supply...
So my question is this...How Can I isolate the power supply from one relay to another? There will be actually 6 realys on the relay board, as follows:
Relay 1: Channel switching - right in front of the FX loop
Relay 2: Engage O.D. circuit to channel 1
Relay 3: Engage boost circuit to channel 1
Relay 4: Engage O.D. circuit to channel 2
Relay 5: Engage boost circuit to channel 2
Relay 6: mute switching - right in front of P.I. input
So, I'm puzzed at this arrangement...I would like to keep things as simple as possible in order to avoid trouble :cry: since I have a very limited knowledge of how this SS stuff works...but I'm willing to learn :grin:
First hand, I thought about using only relays - as per Hoffman Omron - but I would like to use only on power supply for them, however I don't know how I could isolate the DC lines so that while one relay is activated it did not bother his other brothers...
Thanks in advance
With Respect
Best Regards
Rzenc
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Yes, you can power the whole thing from one supply. How many of these do you want to be footswitchable? Do you want them ALL to be independently footswitchable (i.e. 6 footswitches) or do you want to combine them (e.g one footswitch for boost, one for OD, one for channel switch). Once you get that figured out, then you can start to look at what kind of footswitch you need and what is available and work towards that (or else make your own).
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> How Can I isolate the power supply from one relay to another? There will be actually 6 relays...
I'm sitting in a room with six lamps, in a town with 10,000 lamps, all powered from a single utility company supply, nearly all individually switched.
Or if you prefer: your car has headlights, dome-light, instrument lights, radio, horn... all independent, or nearly so. (Headlights may dim a bit if heater fan is max while engine is off or idle.)
You want a "solid" supply which gives a semi-constant voltage whether the load is no lamps or six or 10,000 lamps (or six relays).
You run the two supply wires the length of the town/room/board.
Wire a switch and a relay coil in series, and that across the power supply. All switch+relay chains parallel on the one power supply.
What is a "solid" supply? Relays are not fussy. 20% sag from no-load to full load, 14V to 12V is plenty good; small relays could stand 40% sag 16V-11V. You do need to know the total current of the relays, and IIRC Doug does not quote that. If you have relays in hand, either current or resistance will be marked, do math.