| Author | Message | ||
     david wolf |
hello all. i just picked up an rd112 100 with the EV. its in nice shape, but obviously needs a little work. i found the schematic. the chassis number is 2100RD. is this amp the self biasing type? the first thing i noticed was this ringing sound in the background when it hits low frequencies. kind of sounds like "twinkleing", if that not too stupid. like keys hitting each other, but more trebbly. i pulled out the the output tubes and saw that one was on older 6L6gc and the other was a mesa tube. obviously this needs to be remedied quick. this is why i'd like to know about the biasing. another thing i noticed was the hi/lo power switch doesn't really make a difference. lastly, have any of you used a 212 cab with one of these amps. its not quite as smooth as i'd like it sometimes. also can kind of flipout feedback wise with my delay and chorus on. this amp is so rock and roll. its really amazing. lastly#2, anyone used a seperate tube preamp through the loop? what did you use and what did you think? thank you for any help. david | ||
| Steve Kennedy (admin) Username: admin Registered: 03-2002 |
The RD100 is not self-biasing (it has a bias port like most of the other models). Only the RD-50 models are self-biasing. Are you evaluating the sound of the amp using only your guitar? If not, disconnect all outboard equipment and keep it as simple as possible. Your tinkling sound could be microphonic output tubes or a microphonic cold solder joint internally. Switching the Hi/Lo switch doesn't increase gain... you won't hear any difference if you strike a chord in low power then switch the switch. That switch simply doubles the plate voltage of the output tubes and adds headroom (or the ability to turn it up louder without clipping). You would only hear a difference if you had the amp cranked up all the way into output tube distortion in low power, then change to the High position and the sound would clean up. Your feedback problems with outboard effects could be related to microphic output tubes or perhaps overdriving the 100mV insert jack. Since the MM preamp front-end is solid state and high headroom, I find it better to drive the input jacks from the output of a tube preamp rather than using the insert jacks. Also, most tube preamps won't give you the same feel unless the guitar pickups are directly connected to the the first tube stage. I do this all the time with external preamps and have used the following preamps with great success: Mesa Studio Preamp (My favorite higher-gain tube preamp, high gain and great tone.) Groove Tubes STP-G (Studio Tube Preamp for Guitar) (A full Fender Deluxe-style circuit including extra gain stage and output tubes into a speaker emulator... classic!) Chandler Tube Driver Preamp (Lower gain, but a great "classic-rock" tube sound.) Peavey RockMaster Tube Preamp (Great versatile preamp, good rock-n-roll tone, lots of loops and switching.) Art Power Station Preamp (Solid-state, convincing tube overdrive emulation and extremely high headroom clean capability... very under-rated) Steve |