ADA Depot - A Forum To Support Users of ADA Amplification Gear
Non ADA Gear => Rack Gear => Topic started by: rabidgerry on March 15, 2019, 10:13:10 AM
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Ok well I'm pretty sure I've modded C14 out. Cannot recall much difference. I figured the "one at a time approach" would be best in case doing a few things at once would be too much.
Also
I have swapped R33 and R34 out for 4.7k resistors which is supposed to increase stock voltage the preamp tubes are seeing from 260v to 320v
It's worth mentioning the fact that most of my info comes from a guy's post on this thread from another forum, is it bad manners to post it here? Correct me if I am wrong to do so?
http://www.sevenstring.org/threads/peavey-rockmaster-mods.28608/ (http://www.sevenstring.org/threads/peavey-rockmaster-mods.28608/)
Also I got some gold information from this other forum
https://music-electronics-forum.com/showthread.php?t=12476&page=2&s=be8dab91221614959a18120be092ce7f
And posts by a guy called "fuzznut" seem to shed a lot of light on amps that the rockmaster is very similar too and uses some of this knowledge to suggest a lo pass filter to help take away a harsh edge that the rockmaster can possess. So I tried this for an experiment last night, done in a temporary fashion by jarring a .0022µf cap and it's legs under the resistor R400 basically running in parallel and holy shit it worked!!! I may experiment with other values now to get the right one but not sure which values to try? .0022µf seemed quite a good one to try.
Main aims of modding the Rockmaster, get a better lo mids/lo frequency. So the mods for c4, c5, c14 and possibly c17 all pop into this category on of these caps I've already changed a long time ago.
And possibly get rid of the edgeness/fizz that it can suffer from depending on the setup (I get way more fizz with studio di with impulse setup than I do with live setup). So the lo pass filter possibly has solved this issue already.
And possibly improve the distortion, perhaps a little more gain, not essential but curious to try this mod of Changing the plate resistors to 200k (R3 and R13 only). I think I have the right resistors to achieve this currently.
Might need to order more caps in general for various values.
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Finally got time to try another little mod for the Rockmaster.
I'm going to try a 1µf in place of the 0.47µf cap in C17 on the tube board. It's to allow more low end through apparently. Trying 1µf first as this is the value others have tried.
The caps I got are only 400v, does anyone know if that would be suitable for this kind of mod? They are also huge!! I hope they will fit.
I was thinking of rigging this up in a way that I could attach different caps of different values at will before I settle on the right value, say by attaching two wires in place where the original C17 is now and then using crocodile clips to connect whatever value of cap I wanted. Stupid idea may be?