Thursday, 6 February 2014

Valvette Custom Drive

Thanks to Ice-9 on FSB for the schematic.  Unfortunately the value of the dual linear Gain pot wasn't noted although he suggested it was a low value such as 10K or 25K.  That would seem fine for the Gain B connections but seems low for gain control in the feedback loop which is the Gain A connections.  It does seem to be a low gain overdrive which does reinforce the low value pot suggestion, but rather than experimenting with values of pots you're unlikely to have in stock I think it would make this pedal more versatile to have two separate Gain pots.  If you use a 1M for the Gain A connections and a 10K for Gain B that will allow you to control feedback loop clipping and hard clipping independently rather than increasing or decreasing both simultaneously.   It will also allow you to go much higher gain with the feedback loop pot if you choose to, which may appeal to some people (you could of course reduce that pot value to adapt the feedback loop gain to your own preference).

Remember that the value of the Gain A pot will be effectively reduced by the 1M resistor in parallel with it in the feedback loop, so if you use a 1M pot the maximum resistance will only be 500K.  If anyone does experiment with dual pots then please comment on how it sounded and the value used.

Info about the original:

Introducing the Custom Drive overdrive pedal

If you're into blues or classic rock tones then this pedal is the one for you ...

Designed as the perfect companion to your valve amp, it's main goal is to push your amp into submission and give you those full rich tones without sacrificing the control at your fingertips.

This pedal is definitely not a one trick pony ! The Custom Drive can perform buffering, treble boosts and creamy sustaining leads with all the variations of good old rock and roll chord grit and crunch in between.

You will not find any DSP modeling inside this pedal, only the purest of analog circuits.

The pedal was designed in such a way that it allows the character of you amp / pickup combination to shine through and retain the response of the picking and volume settings on your guitar. Great for comping styles, delicate pickers, slide players etc ... keep in mind that amps with transistor preamp stages generally don't respond well to being pushed by overdrive pedals as it tends to unleash their harsh character ... by all means give it a try, there are some excellent transistor amps out there, but remember that this pedal was not designed for this purpose. It really shines when paired up with a valve amp !

The Custom Drive features a dynamic gain / tone network ... unlike most other pedals on the market today, this pedal does it's filtering inside the gain stage which results in a more open and transparent sound as it mainly affects the clipping and not the essence of your tone. Depending on the settings of the tone control, the gain control will have a different response curve. Although this creates an extended range of settings, we haven't lost sight of the fact that things need to be musical and intuitive to the performing musician. You'll be up and running with this one in no time at all !

The Custom Drive is true bypass wired and 'pop' reduced as you would expect from a quality pedal and will run quite happily on voltages from 9 all the way up to 18 volts DC. Running the pedal at higher voltage results in more headroom and a slightly cleaner and more defined tone... experiment and decide what works best for your individual playing style !


  1. Putting in a mouser order now, I did not need to see this one... so adding more parts to my list
    oh demo is nice... dude has a AB763 Tremolux and this pedal makes it sing...
    will keep ya posted if I can get this one working

  2. Holy Smokes... Mouser wants $16.73 for 1 OPA2107AP... has 2 for $3.50 - I hope those are legit! lol
    Can you use any other IC's for this pedal?

    1. I guess you could try any conventional dual opamp, though the OPA's are quite hifi quality... I'd try a simple TL072, then maybe a 4558 and if you don't like those you can go for more expensive ones, the OP275 is a good candidate, it is not cheap, but not 17USD either ;)

  3. Ah yeah, I see some of the OP275s for about $2.70, will try one of those... thanks!
    I will order the proper ICs later if needed

  4. Ive tried it 3 ways.
    1. I used a 10kDG pot and found the gain to be minimal. The pedal sounded like a clean boost with the gain maxed.
    2. I used a 1M pot for Gain A and a 10K for gain B. This was fine but the 10K pot had no effect on the signal.
    3. The third way which I prefer is to put a 1M resistor on the board in place of the GainB connections and remove that pot completely. Now I just have a 1M gain pot connected to the A connections and this was by far the best. Tons of gain but not too much and the pedal sounds great.

    1. I used a the correct opamp as well op2107ap. You can get free samples from the producer.

    2. Awesome, so I take it that it's verified then?

      That's a shame about Gain B because I think the hard clipping option should be quite useful in this, I wonder if the Gain B pot would work better if lug was connected directly to ground instead of to the 10u cap and then to ground.

  5. Thanks for the tip, onthetundra! I got my samples today from TI (really fast, I live in Europe and it did not take a week...), so time to prepare for this one :)

    1. thx for the tip, i just ordered loads of other free stuff from TI :P

  6. Hi,
    I'm finishing it, and going to test the different pot options (10KDG, 100KDG, B1M and B10K, Ivlark's suggestion of gain B connected to ground directly, and maybe other values)

    is the SPDT a ON-ON,or a ON-OFF-ON, please?

  7. I've just tested the suggestions of Tundra, and I have the same results (normal..)

    i've tested your suggestion, Ivlark with lug 2 of gain B connected directly to ground, but the result is strange: at 7 am (minimum) there's no change, but when I turn it clockwise, the gain decreases and near the maximum, there's a big jump with a very distorted sound, and at the maximum the sound decreases again.
    I 've tried it with a A10K too and there's no change.
    Now the best result is the 1M resistor solution of ontheTundra.

    I'll try with a 100Kdual gang this evening.

    obviously, there are big differences depending of the pickups: with my les paul classic, there's tons of gain... with a strat it's more like the video.

  8. I built this one but it is a bit disappointing :( The folks here say it would have quite some gain, and the video makes me think that too, but mine has a rather mild overdrive only. Well... Not Honeybee-ish mild, but not more agressive than a simple TS (thogh the tone charateristic is way different). I used BS170 (obviously turned 180 degrees than the 2N7000) and two 1M pots. Might the BS170's be the cause for this? Also I find that the pot on the hard clipping section does very little if anything at all, so I'll probably stick with the suggested 1M resistor there too.