Joined: 12 Oct 2013 Posts: 14 Location: California
Posted: Thu Nov 14, 2013 2:05 am Post subject: swapping preamp tubes for less gain
I've been looking at the Randall RD1C, 1 watt tube combo amp with an effects loop and speaker emulated line output. I need a low power bedroom/recording amp. I don't need or want built in modelling effects gee-gaws, programming, USB etc, I've got a pedal board that can do all the effects I need and a Steinberg computer USB audio interface and ART tube preamp setup for recording to my computer. I like this Randall amp for the F/X loop, low watts, and the XLR speaker emulated output- those are just what I need and not so common all together in one amp- but this amp is way gainy with almost no clean headroom, and I need more clean. The only review on youtube (for the head) has it starting to breakup with the volume at 4. So I'm thinking maybe I could swap out the 12AX7 preamp tubes for 12AT7 or 12AU7 tubes and hopefully get a little more headroom out of the preamp. Anyone that has done this on other amps, does the idea sound reasonable or is it hopeless since this particular amp is obviously voiced for primarily distortion?
Maybe look at an amp voiced for what you're wanting to play. I've been down this road trying different preamp tubes to get an amp to sound vaguely how I wanted but in the end just sold the amp and bought something more suited to what I was originally searching for.
Joined: 03 Jun 2007 Posts: 3996 Location: London, England
Posted: Thu Nov 14, 2013 12:11 pm Post subject:
Isn't the idea behind getting a 1 watt tube amp so that you can have lovely tube break up sounds at low volumes? I would go with Gabriel's suggestion and start looking for another amp if you want a louder clean sound.
Joined: 29 Oct 2009 Posts: 573 Location: Sheffield, England
Posted: Thu Nov 14, 2013 6:44 pm Post subject:
I changed the preamp tubes in my 212 DeVille to 12AT7s as I'd heard it gave more clean headroom. I read it on here http://www.justinholton.com/hotrod/ but that link's died now, sadly. It basically says that doing this does what you're looking for. Results will vary with different amps I imagine, but I managed to get quite a bit more volume without breakup than with the 12AX7s.
I also biased my amp a little cooler, which means the power tubes aren't working quite as hard. I imagine this has greater effects than changing the preamp tubes, so if possible try that.
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