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Hi all, newbie here 🙂
I’ve built the Pumped Up Rangemaster from GuitarPCB (love it, except the default input cap choices could have been lower IMHO). While I was building it I found a thread on this forum where photos of some P.U.R.P. builds were posted: https://guitarpcb.com/community/topic/where-are-all-the-rangemaster-builds/
What caught my attention was that on all pictures the C4 cap openings are empty. The kit I had ordered came with a brown tiny cap, I think it says 223 on it (and I surely used it as suggested in the build document).
The P.U.R.P. build document is here: https://guitarpcb.com/wp-content/uploads/2018/06/BD_PURP.pdf
It says: C4 is a hiss filter. Any value between 150p and 470p should do. This will not interfere with the guitar tone as it is too high of a filter even at 470p. Since it will not affect the tone, use what you have. If you need a higher filter add one in parallel.
That sounds all good in my book. So why are (possibly a majority of) builders deciding to not use C4? I mean I doubt it’s because they want to stick to the original Rangemaster schematic, because the P.U.R.P. does contain some updates anyway, and not just the C4 hiss filter. For instance it uses a charge pump, different resistor values, trim pots.
So that’s my question. Why are people choosing to leave out the C4 hiss filter cap during their P.U.R.P. build?
Kind regards,
Seb
Many times the hiss filter is not needed. So many opt to save time and effort by not soldering in the filter cap. If there is hiss, one can go back and solder the cap to the board. Probably just as simple as that.
I would not have guessed that. Having to take the PCB out again to add C4 seems more hassle than putting it in directly.
Thank you for your reply!
Micmac,
I’m a novice about take on the PURP myself.
In your opinion, how low should the cap input be?
Hi Geoffrey,
Sorry for the late reply. I didn’t receive an e-mail notification for this, otherwise would’ve replied earlier.
For my taste using 4n7 for C1 is great. It’s close to the original 5n.
First RM build I did was Der Range from Musikding (link). It starts with 3n3, then adds 2n2 or 6n8. I didn’t like the 3n3 much, it was a bit thin in my JCM800 20W with Humbuckers. The 3n3 + 2n2 combo was fine. The 3n3 + 6,8 was a bit too much.
When I first played the PURP I thought 6n8 was a bit too much as a baseline. It didn’t clean up so nicely like Der Range did with the 3n3 + 2n2 combo. And the PURP combos were way too much for my taste. So in the PURP I ended up with C1 4n7, C2 2n2 and C3 also 4n7. The default sounds great, the combos add more punch but not overly much. Love it. But I guess for you it might be different as I don’t know your personal taste.
It’s worth trying out a few combos to get a feel for what you like. This is a great effect and the input cap can be used to tune it to where you like it best (don’t forget to test input cap as well with guitar volume turned down a bit). If you can breadboard this (I never tried that myself) or have a de-soldering pump it’s not hard.
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