building effects into an amp head

[tomer629]

I want to take the "head" part out of my Egnater Tweaker combo and build a head around it. I also want to build some effects into this head wired to the input jack(or in effects loop). Im thinking a distortion or 3 and maybe a delay and phaser for effects. I would then build a footswitch for switching the effects on and off. I have built 10+ stompboxes so I think I can pull this off, but I have a few questions for the forum.


Any suggestions how I would handle the switching? I assume relays but I have no idea how they work and have never worked with them. Is there a good resource out there about wiring relays relating to guitar effects or amps?


How will the heat from the amp affect the built in stompboxes?


Will the stompbox circuits pick up more noise from being close to the amp head?


Is this is a bad idea?   


I realize this will be a lot of work but it sounds like a fun project and it would be cool to be able just grab my amp and go, without needing to worry about a pedalboard, patch cables, batteries etc.

[tubelectron]

I want to take the "head" part out of my Egnater Tweaker combo and build a head around it. I also want to build some effects into this head wired to the input jack(or in effects loop). Im thinking a distortion or 3 and maybe a delay and phaser for effects. I would then build a footswitch for switching the effects on and off. I have built 10+ stompboxes so I think I can pull this off, but I have a few questions for the forum.


Any suggestions how I would handle the switching? I assume relays but I have no idea how they work and have never worked with them. Is there a good resource out there about wiring relays relating to guitar effects or amps?


How will the heat from the amp affect the built in stompboxes?


Will the stompbox circuits pick up more noise from being close to the amp head?


Is this is a bad idea?   


I realize this will be a lot of work but it sounds like a fun project and it would be cool to be able just grab my amp and go, without needing to worry about a pedalboard, patch cables, batteries etc.

Hi tomer629,

The only FX integration that I have done personnally with full success at this date is putting EHX Holy Grail Nano and TC HOF Mini reverbs in several of my DIY tube amps.

I placed these in front end position as an usual stompbox, but inside the amp, like the idea you have too.

I conserved the FX itself in its original box, only deporting the Reverb pot on the front panel of the amp, and building a small DC regulated 9VDC PSU to feed it (using a small additional transformer if no extra winding was available on the power transformer).

I did not installed a IN/OUT switching / footswitching, only a pair of input jacks "NORMAL" and "REVERB" à la vintage way. The reverb is always powered and engaged.









Not very difficult to do, finally... And I do not experience problems of heat or adverse noise here : all works as it should.

I am currently working on a 2-channel tube amp DIY project where the reverb will be placed in an FX loop placed between the preamp and the power amp, just before the general master volume, using a signal level adaptation (probably based on my MKIIA-LATOR : http://www.diystompboxes.com/smfforum/index.php?topic=113994.0). The Reverb pot will be deported, as on my previous releases, but I will use a relay to FSW the effect this time.

To help your project design if necessary, you can find affordable relay switching boards in kit forms here : http://www.tube-town.net/ttstore/Kits/Choses-utiles/Kit-Double-Relais-Switcher-6-V::5910.html and also FX loop adaptors : http://www.tube-town.net/ttstore/Kits/Kits-divers/Kit-Seriel-FX-Loop-LND150::5973.html.

If like me you plan to install several FX loop units in your amp (each one footswitchable or not), and according to some tests I have made for my project mentionned above, I suggest a serial connexion of the loops better than a parallel one, in order to avoid possible problems of phase cancellation, volume variations, etc.. Between the paralleled loops.

A+!

[tomer629]

Wow those are beautiful amps. I bet they sound great too. Adding a built in reverb pedal to my amp is actually what got me thinking about this project.

Thanks for the great reply, you gave me some more ideas. Is that relay you linked just 1 footswitch? I think I'm gonna need 4-6 switches.

[tubelectron]

Wow those are beautiful amps. I bet they sound great too. Adding a built in reverb pedal to my amp is actually what got me thinking about this project.

Thanks for the great reply, you gave me some more ideas. Is that relay you linked just 1 footswitch? I think I'm gonna need 4-6 switches.

Thanks !

About the reverb addition :

1 - If your amp is vintage-style like mine in the post above, you can simply install the reverb like I did : in front end. It works very well : you can heard the sound of these amps on my small non-commercial website guilhemamplification.jimdo.com.

2 - If you want to FSW the reverb (unlike me, where I used two input jacks "normal" and "reverb"), then you will need a DPDT relay to bypass the effect.

3 - I personnally think that deporting the foostswitch of the effect itself in an external pedal is a bad idea, for fear of adverse noises.

4 - Replacing the 3PDT footswitch of the pedal by the relay (forgetting the led switching) would be the best, because the signal wires will be the shortest.

5 - A good compromise would be the external relay switching, like the TT Double Relay Switcher linked in the post above, if you want something already prepared.

About several effects addition :

1 - they should be placed in serie, to avoid sound problems like phase cancellation, etc...

2 - What's best between placing them in the front end vs in the FX loop is questionable - on a single channel amp.

3 - if like me you intend to build a dual-channel amp (not a single channel vintage-like) then you can't place the effects in the front end, but only in the FX loop, in order to effect both channel similarly. Otherwise, you will have unavoidable volume variation problems when you will shift from clean to lead channel (for example a flooding reverb when the lead is engaged).

4 - Doing that, I suggest placing the FX in that order (according to my experimentations) : send > distortion/fuzz/overdrive effects > phasor/chorus/flanger effects > delay/reverb effects > tremolo effect, if you want one > return.

I think that the little TT relay board has 2 independent switchable relays, controled via a stereo jack cable, so you could be able to FSW independently 2 effects. I have that kit, but still not assembled it  to check. If you need more footswitching, then you will need one relay for each footswitched effect plus its wires to go to the FSW pedal, and a multi-pin connector = a DIY design is required.

In my dual-channel amp project, I won't go so far as you intend, since I don't want to integrate the effects in the amp itself, but only the reverb. Here's my idea :

- I would use the TT double-relay with one relay to control the reverb, the other one to control the FX loop, with all other effects externally placed.

- I would install those FX-looped effects (2 or 3) velcro-ed on a little woodboard with rubber feets, put on the top of the amp,

- Then I would link serially these effects as usual and go to the Send/Return jacks of the FX loop with custom-made short cables,

- I would have installed in the amp an internal regulated DC power supply with several outputs to feed these effect directly from the amp via power patchcables.

No cable and no stompbox collection on the floor in your feets is the result... I personnally find that is is more versatile and less complex than integrating a bunch of effects in the amp, but it's me  ...

A+!

[tomer629]

Thanks tubelectron for another great reply. Very informative.

The amp I plan to do this with is Single channel, with effects loop. Adding the distortion pedals before the input will basically give me 2 more "channels".

So I was thinking I'd put a few dirt pedals in series in front of the input, and maybe a delay and phaser in the loop. I will just use normal 1/4" plugs to connect the effects in the loop, allowing me to insert other effects in the loop later if needed. The dirt pedals will be hard wired in series between the input jack and the amp.

Thinking now that I'm going to try to limit myself to 4 total pedals built into the amp. I think that will be plenty complicated already. Well 5 if I decide to add reverb, but that won't need a footswitch, I would just put a switch on the back panel to bypass reverb if I ever want to turn it off.


I won't be using actual stompboxes. I will be building the effects right onto a panel in the head. So they won't get the usual shielding from noise that a stompbox enclosure provides. If noise is a problem I guess I could build them into an enclosure thats mounted in the head,  and run the wires to the front panel.

As for powering the pedals, you said you installed a internal regulated DC power supply. Is this just basically a "wall wart", but built into the amp itself instead of plugged into an outlet? If possible could you point me to some resources about doing something like that? When I try googling all I find are normal DC power supplies that you plug into the wall.

Another question. don't DC power supplies give off a lot of noise? I always thought that was one of the reasons they were built into the wall wart, instead of just built into the pedal. I could be totally off base on that though.

[tubelectron]

Thanks tubelectron for another great reply. Very informative.

---> Thanks !

The amp I plan to do this with is Single channel, with effects loop. Adding the distortion pedals before the input will basically give me 2 more "channels".

---> OK.

So I was thinking I'd put a few dirt pedals in series in front of the input, and maybe a delay and phaser in the loop. I will just use normal 1/4" plugs to connect the effects in the loop, allowing me to insert other effects in the loop later if needed. The dirt pedals will be hard wired in series between the input jack and the amp.

---> OK.

Thinking now that I'm going to try to limit myself to 4 total pedals built into the amp. I think that will be plenty complicated already. Well 5 if I decide to add reverb, but that won't need a footswitch, I would just put a switch on the back panel to bypass reverb if I ever want to turn it off.

---> OK.

I won't be using actual stompboxes. I will be building the effects right onto a panel in the head. So they won't get the usual shielding from noise that a stompbox enclosure provides. If noise is a problem I guess I could build them into an enclosure thats mounted in the head,  and run the wires to the front panel.

---> Yes, you may face noise or oscillation problems, but enough shielding would be the cure.

As for powering the pedals, you said you installed a internal regulated DC power supply. Is this just basically a "wall wart", but built into the amp itself instead of plugged into an outlet?

---> Yes. Or there is an available winding of the suitable AC voltage on the power transformer (i.e. Val-King, Orient-Express) or I add a small encapsuled transformer to give the required AC voltage (i.e. The Comet).

If possible could you point me to some resources about doing something like that? When I try googling all I find are normal DC power supplies that you plug into the wall.

---> Oh, it is very simple : I use a bridge rectifier, a 1000µ/16V cap, a 7809 TO-220 9VDC voltage regulator, a 1µF/63V mylar cap, all built on a small VERO stripboard, and that's all. It's basically the datasheet application of the 78XX voltage regulators...

Another question. don't DC power supplies give off a lot of noise? I always thought that was one of the reasons they were built into the wall wart, instead of just built into the pedal. I could be totally off base on that though.

---> If you place your DC power supply far away from the input stages, there is no problem. If you don't have the additional transformer, this is even easier, since there is no additional source of hum induction.

---> I think that one of the reason of the "Wall-Wart" adaptor is that it is more easy to make the stompbox comply with electrical norms and rules of each country where stompbox is sold : only the adaptor is concerned because of the AC mains, not the stompbox. And of course yes, the noise/induction argument is valid if you have to include a transformer inside a compact stompbox, indeed...

A+!

[mth5044]

Man, you'd have a much easier time building something to put on top of the head. Multiple ins and outs to patch things in to the front end and/or the effects loop. No fussing with high voltage either. A simple chassis full of a bunch of effects, four little feet, and set on top of the amp. Does your amp have enough room for all the knobs for all 4 of the pedals? Plus if you get another amp, you can take all these effects with you instead of having to build a new ones.

That being said, there are plenty of amps like what you are trying to do, so ultimately it could end up really cool and useful!

[tomer629]

I appreciate the input mth5044. It would be easier to to build something that goes on top of the head and is connected with patch cables. But it wouldn't be nearly as cool

Also I am planning to remount my tweaker 1x12 combo into a head anyway so I figured I'd add a few pedals while I'm at it.

Since I will be building the stompbox circuits into the head, I can arrange the knobs however I want to and I think I should be able to fit 2 sets of knobs on either side of the amp. 

[Hatredman]

There are some old grumpy guys (like myself) that don't think this is a good idea.

With everything inside the head, if something breaks in the middle of a song it can render your amp silent. If it's an external multieffect unit on top of the amp, you can still plug your guitar directly on the head and be able to finish the show.


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[tomer629]

With everything inside the head, if something breaks in the middle of a song it can render your amp silent. If it's an external multieffect unit on top of the amp, you can still plug your guitar directly on the head and be able to finish the show.

I was thinking I would install a switch that would send my signal straight from the input into the amp, or through my effects and then into the amp. This switch would actually be the only mod to the Amp itself (aside from remounting it in a head).

If one of my added circuits has a problem I can just bypass everything. Could also of course bypass each circuit individually with the footswitches. The built in pedals that I put in the effects loop will just plug into the amps loop with normal patch cables. No modding needed there.


I do appreciate the input though. Even from those saying this is a bad idea   You bring up valid points.