2006 Splawn Quickrod mods

[Setneck]

Hi!

I have currently on loan a Quickrod dated 2006, 3 preamp tubes version. Since now I have used Bogner Ecstasy, which is very versatile amp, but I'm starting to feel that QR sounds better in my band’s mix. Thus I am thinking about buying it, but I miss XTC’s versatility a bit . So, I have couple of questions:

1. would it be possible to make loop on/off footswitchable? The loop in QR colours the tone too much for my tastes so I’d like to be able to switch on the loop only while I use effects (which I do mainly for solos, playing rhythms w/o any effects). As I use external boost for solos in my pedalboard I could use boost button in the footswitch for that. If it’s possible, what could be the simplest way make such mod?

2. I need some kind of crunch channel, as I am not fancy messing with volume knob in my guitar. For my application gear3 sounds perfect, and hitting OD1 doesn't do the job now. In early QR's OD1 is 47K to ground after first gain stage. So I see two ways to solve the problem:

a) changing resistor value, but what value seem to You to do the job?

b) as I won’t going to use internal boost I could mod the Solo pot (or entire solo circuit) to act as a “gain control” for OD1 mode (as pot is variable resistor ) Could I simply link that pot with the place of OD1 resistor on pcb? And what pot value should I use? 1M like for overall gain?


Thanks in advance for Your help.

Regards, Andy

[pdf64]

Are you able to attach schematics to your message, or links to schematics?
It may also be worth posting in a splawn specific forum.

[Setneck]

Hi!

I have already posted that on Splawn forum but it seems that there are only players there, not technicians . They told me to buy midi device for that .

Anyway, I have some schems posted already on the other forum. Don't know if they are 100% correct.

[pdf64]

The schematic doesn't seem to show an fx loop?
The 'solo' boost control could be re-assigned so as to be in series with the 47k resistor R8, and that should be able to bring OD1 progressively closer to OD2. A possible issue may be oscillation; there's a lot of gain in there and connecting something that's physically at the end of the gain chain to a point electrically early on in the chain is bad practice.

[Setneck]

No, the schematic contains only preamp section, loop is ss, series one. Unfortunately that is the only one schematics I have.

As for the OD1 mode, the idea was to replace the 47K resistor with the pot (which is still a variable resistor ) to actually keep the OD1 gain much lower than it is now. What can be done to the circuit to prevent the possible oscillation?

Regards, Andy

[pdf64]

Well, to get the OD1 gain much lower, the 47k could be brought down to say 10k. That will also roll off some low end but that may be a good thing? If there's excessive bass loss, the cap before it could be replaced with say 0.1uF.
Oscillation may not be a problem as there's a lot of high frequency roll off along the gain chain.
Another / additional option is to move the solo boost control to be in parallel with R19, with a resistor in series with the boost control, which will set the gain level in the 'boost off' mode. 10k to 47k, in series with the boost pot will bring the gain down a lot. This method is unlikely to have any oscillation problems.