RT2/50

[seeker]

Received my power amp yesterday, unplugged my Mesa 20/20 and connected the new amp. All settings going into the power amp were untouched. Strange thing is the level settings on the Randall needed to be 2x versus the Mesa 20/20 Dynawatt EL84. I'm wondering why a 100 watt amp has less output than a 20 watt ? The Randall is used, but relatively new, with new Ruby tubes. I suppose I should check the bias levels before I look elswhere.
The ohm settings from the outputs are correct, and running in stereo mode.

Any suggestions ?


Thanks,

Howard

 

[3 Mile Stone]

Hey Howard,

That is weird. I will say having owned a Boogie 20/20 that it is one loud little sucker, but to be so far off I'd have to think something is wrong. I'm at a loss though. Got any other tubes laying around that you can put in and re-bias?

 

[seeker]

Tommy,

I don't have any tubes that fit, just some EL84's . I have ordered a pair of Mullard EL34's and a pair of Tung Sol 5881's . I'll check the bias on the Ruby's when I get home.


Thanks,

Howard

 

[JKD]

yeah, definately check the bias. When my RM100M arrived, the pots had drifted in shipping and the tubes were almost 50% low...unless the seller swapped from 6L6 to EL34s and forgot to rebias of course.

 

[RD/MAN]

Guys,

One thing to know about Randall amps is that we design the "Master" level controls using audio taper pots meaning that they turn on very slow and gradually get louder as you turn them up, so it's not uncommon to run the "Master" level on an MTS amp at 12 o'clock or higher. Most Level controls or Master volumes on other tube amps in the market, including the Boogie amps have Linear taper pots, meaning the pot turns on very fast and basically gives you full output at 12 o'clock. That's why they seem so much louder at a lower volume settings. It's perfectly ok to set the "Master" level control on the MTS amps or RT2-50 at 2-3 o'clock to get the volume that you need.

However, you should check the bias on the power tubes, because the bias will float over time. If it's used you may also want to put a fresh set of preamp tubes in as well. A faulty preamp tube would easy cause volume loss.

I hope this helps.
Thanks!!

 

[metalmm785]

It's great to see you back R/D Man.

 

[seeker]

RD/MAN,

Hey thanks ! That was my next question, whether the pots were the same or not, and that answers it ! Next question : When you bias the tubes, is the bias on the front panel (top) for the tubes on the left , or right? ( facing the front of the amp). I assume they're paired , left side right side.

Thanks,


Howard

 

[seeker]

Well, I discovered the tube configuration by installing new tubes, Tung Sol 5881's on the left and Mullard EL34's on the right . After 5 minutes one Tung Sol blew the Fast Blo fuse for some reason, so, for those of you who are not sure, the top bias level adjustment is for the tubes on the left (pair) . I replaced the new Tung Sol tubes with old Ruby tubes and everything is fine. (Oh, after visiting my local electronics store for some .25 ma fuses ! )
I'll have to send the Tung Sols back to the dealer, maybe they will replace them.

Anyone else have a problem like this with Tung Sol 5881's ?


Howard

 

[RockManiac]

Howard, I've also got an RT2/50. If you look at the amp from behind, the right pair of tubes is for channel 1, the left pair for channel 2.

 

[seeker]

Rock,

Hey thanks , I have it all sorted out now. Have you blown any fuses ?
Are you satisfied with your amp so far ?

Just curious,


Howard

 

[RockManiac]

Howard, good to hear that you have solved your problem. No, I have never blown any fuse. I use my RT2/50 with an M4 and a Randall MTS 212 cab, I am very happy with this combination.

Al

 

[seeker]

Update- I replaced the fuse, and since I had a box of them I tried the 5881's again, this time it worked perfectly. Must have been a bad fuse on the brink, then the new tubes took it over the edge. LOL
The OTHER problem I discovered is since I'm running 2 M4's in stereo , I had a strange problem with channel 1 AND 2 coming on at the same time on one of the M4's.(?).... That reduced the output considerably on the right side , and I didn't notice it !
So, after all the problems...........this power amp kicks some serious butt. Now the power is all there, I'm up to 3 on the volume knobs and it has way more dB's than I need.

Howard

 

[jmgman70]

I love the RT/250,glad you got it going on....