| Author | Message | ||
| Steve James (sjturbo) Username: sjturbo Registered: 01-2011 |
Morning, I have a stock MM112RDFifty RevA and have read that converting to RevE will make significant sonic changes. Has anyone on the forum done them and what were the benefits. I'm somewhat reluctant to change the stock amp unless it makes positive changes in the drive channel or tonal changes in general. Inputs will be greatly appreciated! | ||
| Ed Goforth (ed_goforth) Username: ed_goforth Registered: 06-2006 |
There are some of those mods that make a difference, depending on what you after tone wise. The early RD-50's starved the 12ax7 plates so much that when setting the Limit gain higher turned to mud! Later they stared rebiasing the 12ax7 so that they could sing better. I work on them all the time and always am finding better tones. I like to to get more plate volatge but not too much, keeping the Gain articulate as the gain is turned up making full use at all settings. Also some had the Mid set kind of high and it could sound honky in the midrange. They can also use a tad more bass and that can be done fairly easily as well. They are capable of being aweome sounding/loud little sleepers. Recapping is important as well and upping some values does not hurt either to tighten the bass response, less farting in the low end. A simple effects loop can be added without coloring the tone since you really do not need buffers with the solid state preamp, the way it is designed one could use the Line out jack and install a stereo jack there and split the signal from the preamp before the driver wire it up as a pre amp interupt, reinsert style using a "Y" cable for delay's etc. I have been able to get some tones like a good Mesa Mark 1 blues tone without the harshness or buzziness, just listen to Chris Cain's tone. Basically Groove tubes GT6L6 GE's and a EVM12L old style 200 watt version sounds awesome in these. I also do mods that enhance the sound even more, but at least the caps and tubes and even a speaker will make a big difference in tone with these amps. | ||
| Ed Goforth (ed_goforth) Username: ed_goforth Registered: 06-2006 |
Hi Steve, I just updated another Rev A to a Rev E. There are a few changes involved Basically the Rev E will have a bigger sound and be quieter, noise/hiss-wise. The mods/updates sound better to a lot of players, but some prefer the older Rev's over the new. I have worked on many variations (Rev's). The older RD's can sound sweet with a few tweaks, the newer RD's are a bit more bolder, but not in a bad way! People tell me the middle production RD's sounds pretty good with the updated transistor driver section, which was one of the first Revisions and some have said the later versions sound very good, with the rebiasing of the 12ax7 section. The earlier model really starved the second 1/2 of the 12ax7 and it would get very muddy at higher gain settings, where the rebiasing of the 12ax7 opens up the overdrive tone more. Bob W. posted a schematic that changes plate and cathode resistors on the 12ax7 and it made a huge difference. I have tweaked that area for quite some time now, and to me it sounds pretty good. Poeple say the older RD's can sound a little anemic in comparison. But to each their own, tone is subject to everyone. Personally I think you would like the update  If you go to www.myspace.com/goforthsound and click onto the Chris Cain clip, you will hear Chris playing through a RD-50 with the Mid Shift switch "on", that I did the update on. That was not Chris' RD-50 though, it belonged to Richard Lunetta, who I sold it to after the mods and he had Chris play through it at a club in Corona Ca. Chris' amp that I have seen and heard (White) is stock with GT 6L6 GE's and a EVM12L speaker. He usually runs the gain at about 3-4 and volume at 3-4. In those settings, the amp sounds great for blues, but any gain settings past 4-5 can get pretty muddy stock. Rebiasing the 12ax7 will help make the Limit drive more open and articulate and more usable for rock or anything requiring a bit more gain, probably not much good for Metal though without help from a pedal for really satuarted tones. |
Tue, 03/25/2014 - 09:34
#1