DRRI mods

Graybeard27 · April 30th, 2006, 01:40 PM

There are a few mods I want to do with my DRRI, mainly because of the fizziness I get with OD pedals.

First of all I think I want to remove the bright cap. Can I do this myself, or should I let a tech do it? Should I do it to both channels, or leave one with it on? Another thing I read was I could change the 100k slope resistor to a 91K or 82K, but I have no idea where to get these or how to do it.

Also, since my bday is coming up (may 26 woot!) I think I'll get a new speaker. Right now i'm thinking about gettin a weber 12F150. Some other good ones I've heard about are eminence cannabis rex and red white and blues, weber california 12, and something C12N. I think that I might want one with a little more headroom, if I like the OD pedal I'm going to get. Which do you think is best? What's the difference between alnico and ceramic? Also is this another DIY job?

Thanks for all replies.

zook · April 30th, 2006, 04:54 PM

I think the bright cap is the same as in the earlier amps. You will fing a small capacitor accross pin one and the sweep of the volume control. That would be the pin closest to the input and the middle one. All you need to do is clip it out of the circuit.

Winnie

Graybeard27 · April 30th, 2006, 07:05 PM

So do I just unplug the amp and unscrew the board? Do I have to drain anything?

petebradt · April 30th, 2006, 07:14 PM

Quote:

Originally Posted by Graybeard27

So do I just unplug the amp and unscrew the board? Do I have to drain anything?

You should NEVER stick both hands inside a tube amp without draining the filter caps.

You can make a simple jumper consisting of a couple fo alligator clips about 3-4" if wire on each side and a 10K, 10-watt resistor.

Remove the rectifier, be it tube or SS.

Clip one alligator clip to a known good ground, and the other to one of the filter cap leads (drain one, you drain 'em all).

Wait about 10-15 minutes. By then your caps will be drained.

Do whatever work you have to do.

Disconnect your jumper (bad things can happen if you don't, and fire up the amp).

Replace the rectifier tube.

You're done.

TDPRI · April 30th, 2006, 07:46 PM

Don't remove the Bright cap just clip one side and move it out of the way. That way if you or a future owner wants to reattach it it will be ready to solder.

A new 12" will help, but don't expect miracles.

When I had a DRRI I experimented with speakers and clipped the bright cap. Not that much changed.

Then I bought some NOS Power Tubes and rebiased the amp to run hotter and that made the biggest difference. It warmed up the amp considerably.

Just to test it, I put the stock tubes back in and biased the amp hot and I found that the rebiasing was the thing that made the greatest difference.

I put a Celestion Vintage 30 speaker with an Alnico magnet in mine and that warmed it up some too.

In the end, I suggest, better power tubes, rebiasing and a "browner" sounding speaker. All together these things made the amp sound much more like a vintage DR.

Paul Green
PS. Finally, I sold it and bought a '65 Princeton Reverb and put my 12" Celestion Vintage 30 speaker in that and I've never wanted another amp since.

Crazy Gra · April 30th, 2006, 09:17 PM

+1 on the bias, my DRRI was set very cold from the factory (18mA !) Should be set to between 22 to 27mA, I measured the plate voltage at 420v (they can and do vary from unit to unit) so I set the bias at 25mA for a Static Dissipation Wattage of 10.5w. 6v6gt can take 12w as a MAXIMUM, please don't aim for 12w it's just a MAXIMUM! Tube life will be reduced the hotter you bias.

Biasing to 25mA made a huge difference, the amp has lost a lot of icepick tone, is much fuller sounding, also I can make more use of the treble control.

My output tubes are JJ 6v6gt, preamp are JJ Ecc83s and Mullards. This also made a worthwhile change to the tone.

Honestly doing those two things has made a massive difference to the tone, the amp is something I now want to listen to.

It sounds pretty good at volume 3 in channel 2 and the Tubescreamer has come alive. Turn up the volume and things get better and better.

As a caveat though my amp is an Australian only model with a pine cabinet and Jensen C12N as standard.

Mate, for more headroom you'd be better looking at putting in 6L6 (6V6 is 6L6 little low power brother) and biasing to suit.

As far as I remember the bright cap (if we're talking the same cap) is just on the Vibrato channel. It's C10 on the (green pcb) board layout.

All the jobs you mention are DIY except the biasing, just be careful if you do the biasing you are dealing with high voltages!!!!! Also drain any power from the amp before sticking your fingers in there. Mate get yourself a good book "How To Service Your Tube Amp" is a good one.

Alnico is the "vintage" magnetic material makeup used and ceramic the more modern version, too complex for here, maybe another book purchase is in order?

Big Lug · May 1st, 2006, 09:06 AM

Hold off on clipping the bright cap until you:

1. Replace the GT tubes with at least JJs. Then get it biased properly. Fender tends to ship the DRRI out biased on the cold side and that combined with the GTs contributes to shrillness.

2. Replace the speaker with a Weber 12F150. A lot of people like the Jensen C12N the DRRI comes stock with. Weber's 12F150, though, is Ted's replica of the original ceramic Jensen and as almost everyone who has installed this speaker will attest to, it is the speaker for the DR or DRRI. Get Ted to break it in for you prior to shipping; it won't be completely broken in but it will significantly speed up that process.

These two simple changes can make a huge difference in the amp's tone--taming the shrillness and helping to open it up. If you are so inclined you could replace the output transformer with a better quality one. Mercury Magnetics manufactures first class replica trannies for many amps including the DR/DRRI. Go to their site and read what some artist, such as Peter Stroud, have to say about this.

Now at this point some people might be saying with all those changes (and the associated costs) why not get a "real" BFDR or the more affordable SFDR? Up to you. Be aware, though, there can be significant "tuning up" considerations if you get one.

At the minimum change the tubes, rebias, and consider replacing the speaker. After doing so you may not want to cut that bright cap which, by the way, helps make the "cut" in a band situation.

Good hunting for your tone.

bagpipe · May 1st, 2006, 09:31 AM

Note that on the DRRI, the Normal channel doesnt have the bright cap, its only on the Vibrato channel. If you feel that the Vibrato channel is "warmer", and closer to the sound you're after, then it might be worth removing the bright cap. Note that to remove this bright cap, you pretty much have to take the whole amp apart ie remove the amp from the cabinet, and remove all of the contol knobs. You then have to remove the small backward facing PCB. I wouldnt attempt it if I wasn't comfortable with stripping down electronic "doodads".

Graybeard27 · May 1st, 2006, 10:04 PM

Thanks for the advice guys. I have one more question though. How much would the new tube upgrade cost approx?

GUITARmole · May 2nd, 2006, 04:08 AM

About $88 at Eurotubes:

https://ssl.eurotubes.com/cart/index...category_id=35

Oh...and happy B-day...to you and me (mine's the same day!).

As for speakers I have a Mojo Greenback clone in mine and love it. I prefer Celestion types in the DR as they especially improve the overdriven tone. If you go for a new Eminence they sound good clean with a nice fat breakup when you really crank them.

Brass Saddle · May 2nd, 2006, 11:09 AM

I know virtually nothing about the inner workings of my DRRI, but I can say that I had NOS tubes put in it about a year ago along with a rebias, and it was a dramatic difference. As others have said, I believe the bias was probably the biggest change. It lost a little "airy-ness," but the added warmth and fullness of tone were really a pleasant surprise. I went a little nuts on "vintage" NOS tubes, but I think a good set of JJs or similar would have yeilded similar results.

jonzer · May 2nd, 2006, 01:50 PM

I never think about stuff like this. What's different about me than you guys?
I've had my DRRI for about three years and I bought it used. I haven't had it rebiased, changed a tube or the speaker. I've gigged with it a lot. A lot of drinks have been spilled on it. A lot of butts have sat on it. Nothing has torn on the cab or the tolex.

I think playing through it a lot has done more for it than any mods I could have thought of. I just wanna play my stuff, not mod it.

lpacilio · May 2nd, 2006, 02:45 PM

First I retubed with JJ's - big improvement.

Then I put in an Eminence Cannabis Rex - HUGE IMPROVEMENT! I can't emphasize enough how good the C-Rex sounds in a DRRI. It takes the edge right off the brittle highs.

Scott S · May 2nd, 2006, 05:35 PM

Quote:

Originally Posted by jonzer

I never think about stuff like this. What's different about me than you guys?

You're better off than the rest of us. We'll tweak and tweak and never be happy.

April 30th, 2006, 01:40 PM	#1 (permalink)
Graybeard27 TDPRI Member Join Date: Apr 2006 Posts: 21	DRRI mods There are a few mods I want to do with my DRRI, mainly because of the fizziness I get with OD pedals. First of all I think I want to remove the bright cap. Can I do this myself, or should I let a tech do it? Should I do it to both channels, or leave one with it on? Another thing I read was I could change the 100k slope resistor to a 91K or 82K, but I have no idea where to get these or how to do it. Also, since my bday is coming up (may 26 woot!) I think I'll get a new speaker. Right now i'm thinking about gettin a weber 12F150. Some other good ones I've heard about are eminence cannabis rex and red white and blues, weber california 12, and something C12N. I think that I might want one with a little more headroom, if I like the OD pedal I'm going to get. Which do you think is best? What's the difference between alnico and ceramic? Also is this another DIY job? Thanks for all replies.

April 30th, 2006, 04:54 PM	#2 (permalink)
zook Tele-Holic Join Date: Aug 2003 Location: Northeast Kingdom, Vermont Posts: 833	I think the bright cap is the same as in the earlier amps. You will fing a small capacitor accross pin one and the sweep of the volume control. That would be the pin closest to the input and the middle one. All you need to do is clip it out of the circuit. Winnie __________________ I have noticed that happy people are often evaluating themselves and unhappy people are always evaluating others. -William Glasser

May 1st, 2006, 09:06 AM	#7 (permalink)
Big Lug Tele-Holic Join Date: Aug 2003 Location: Lower Mainland, the Great White North Posts: 651	Hold off on clipping the bright cap until you: 1. Replace the GT tubes with at least JJs. Then get it biased properly. Fender tends to ship the DRRI out biased on the cold side and that combined with the GTs contributes to shrillness. 2. Replace the speaker with a Weber 12F150. A lot of people like the Jensen C12N the DRRI comes stock with. Weber's 12F150, though, is Ted's replica of the original ceramic Jensen and as almost everyone who has installed this speaker will attest to, it is the speaker for the DR or DRRI. Get Ted to break it in for you prior to shipping; it won't be completely broken in but it will significantly speed up that process. These two simple changes can make a huge difference in the amp's tone--taming the shrillness and helping to open it up. If you are so inclined you could replace the output transformer with a better quality one. Mercury Magnetics manufactures first class replica trannies for many amps including the DR/DRRI. Go to their site and read what some artist, such as Peter Stroud, have to say about this. Now at this point some people might be saying with all those changes (and the associated costs) why not get a "real" BFDR or the more affordable SFDR? Up to you. Be aware, though, there can be significant "tuning up" considerations if you get one. At the minimum change the tubes, rebias, and consider replacing the speaker. After doing so you may not want to cut that bright cap which, by the way, helps make the "cut" in a band situation. Good hunting for your tone. __________________ "Set my compass North I've got winter in my blood." Robbie Robertson

May 1st, 2006, 09:31 AM	#8 (permalink)
bagpipe Tele-Meister Join Date: Mar 2004 Location: Ottawa, Ontario Posts: 235	Note that on the DRRI, the Normal channel doesnt have the bright cap, its only on the Vibrato channel. If you feel that the Vibrato channel is "warmer", and closer to the sound you're after, then it might be worth removing the bright cap. Note that to remove this bright cap, you pretty much have to take the whole amp apart ie remove the amp from the cabinet, and remove all of the contol knobs. You then have to remove the small backward facing PCB. I wouldnt attempt it if I wasn't comfortable with stripping down electronic "doodads". __________________ "Assistant to the Travelling Secretary"

May 2nd, 2006, 11:09 AM	#11 (permalink)
Brass Saddle TDPRI Member Join Date: May 2005 Location: Atlanta Posts: 33	I know virtually nothing about the inner workings of my DRRI, but I can say that I had NOS tubes put in it about a year ago along with a rebias, and it was a dramatic difference. As others have said, I believe the bias was probably the biggest change. It lost a little "airy-ness," but the added warmth and fullness of tone were really a pleasant surprise. I went a little nuts on "vintage" NOS tubes, but I think a good set of JJs or similar would have yeilded similar results. __________________ It's not a lie if you believe it.....

April 30th, 2006, 07:05 PM	#3 (permalink)
Graybeard27 TDPRI Member Join Date: Apr 2006 Posts: 21	So do I just unplug the amp and unscrew the board? Do I have to drain anything?

April 30th, 2006, 07:46 PM	#5 (permalink)
TDPRI Administrator Poster Extraordinaire Join Date: Mar 2003 Location: TDPRILAND Posts: 5,725 36 Photos	Don't remove the Bright cap just clip one side and move it out of the way. That way if you or a future owner wants to reattach it it will be ready to solder. A new 12" will help, but don't expect miracles. When I had a DRRI I experimented with speakers and clipped the bright cap. Not that much changed. Then I bought some NOS Power Tubes and rebiased the amp to run hotter and that made the biggest difference. It warmed up the amp considerably. Just to test it, I put the stock tubes back in and biased the amp hot and I found that the rebiasing was the thing that made the greatest difference. I put a Celestion Vintage 30 speaker with an Alnico magnet in mine and that warmed it up some too. In the end, I suggest, better power tubes, rebiasing and a "browner" sounding speaker. All together these things made the amp sound much more like a vintage DR. Paul Green PS. Finally, I sold it and bought a '65 Princeton Reverb and put my 12" Celestion Vintage 30 speaker in that and I've never wanted another amp since.

April 30th, 2006, 09:17 PM	#6 (permalink)
Crazy Gra NEW MEMBER! Join Date: Apr 2006 Posts: 1	+1 on the bias, my DRRI was set very cold from the factory (18mA !) Should be set to between 22 to 27mA, I measured the plate voltage at 420v (they can and do vary from unit to unit) so I set the bias at 25mA for a Static Dissipation Wattage of 10.5w. 6v6gt can take 12w as a MAXIMUM, please don't aim for 12w it's just a MAXIMUM! Tube life will be reduced the hotter you bias. Biasing to 25mA made a huge difference, the amp has lost a lot of icepick tone, is much fuller sounding, also I can make more use of the treble control. My output tubes are JJ 6v6gt, preamp are JJ Ecc83s and Mullards. This also made a worthwhile change to the tone. Honestly doing those two things has made a massive difference to the tone, the amp is something I now want to listen to. It sounds pretty good at volume 3 in channel 2 and the Tubescreamer has come alive. Turn up the volume and things get better and better. As a caveat though my amp is an Australian only model with a pine cabinet and Jensen C12N as standard. Mate, for more headroom you'd be better looking at putting in 6L6 (6V6 is 6L6 little low power brother) and biasing to suit. As far as I remember the bright cap (if we're talking the same cap) is just on the Vibrato channel. It's C10 on the (green pcb) board layout. All the jobs you mention are DIY except the biasing, just be careful if you do the biasing you are dealing with high voltages!!!!! Also drain any power from the amp before sticking your fingers in there. Mate get yourself a good book "How To Service Your Tube Amp" is a good one. Alnico is the "vintage" magnetic material makeup used and ceramic the more modern version, too complex for here, maybe another book purchase is in order?

May 1st, 2006, 10:04 PM	#9 (permalink)
Graybeard27 TDPRI Member Join Date: Apr 2006 Posts: 21	Thanks for the advice guys. I have one more question though. How much would the new tube upgrade cost approx?

May 2nd, 2006, 04:08 AM	#10 (permalink)
GUITARmole Tele-Afflicted Join Date: Mar 2005 Location: Portland, OR Posts: 1,147 50 Photos	About $88 at Eurotubes: https://ssl.eurotubes.com/cart/index...category_id=35 Oh...and happy B-day...to you and me (mine's the same day!). As for speakers I have a Mojo Greenback clone in mine and love it. I prefer Celestion types in the DR as they especially improve the overdriven tone. If you go for a new Eminence they sound good clean with a nice fat breakup when you really crank them.

May 2nd, 2006, 01:50 PM	#12 (permalink)
jonzer Tele-Afflicted Join Date: Jun 2005 Location: Virginia Posts: 1,116	I never think about stuff like this. What's different about me than you guys? I've had my DRRI for about three years and I bought it used. I haven't had it rebiased, changed a tube or the speaker. I've gigged with it a lot. A lot of drinks have been spilled on it. A lot of butts have sat on it. Nothing has torn on the cab or the tolex. I think playing through it a lot has done more for it than any mods I could have thought of. I just wanna play my stuff, not mod it. __________________ http://816rocks.com/

May 2nd, 2006, 02:45 PM	#13 (permalink)
lpacilio Tele-Meister Join Date: Jan 2005 Location: Upstate NY Posts: 252	DRRI Mods First I retubed with JJ's - big improvement. Then I put in an Eminence Cannabis Rex - HUGE IMPROVEMENT! I can't emphasize enough how good the C-Rex sounds in a DRRI. It takes the edge right off the brittle highs. __________________ The music business is a cruel and shallow money trench, a long plastic hallway where thieves and pimps run free, and good men die like dogs. There's also a negative side. - Hunter S. Thompson (RIP)