August 2012 \ Tech Tips \ Ask Amp Man \ Taming A Fender Hot Rod Deville

Taming A Fender Hot Rod Deville

Jeff Bober
Premier Guitar August 2012


Fender’s popular Hot Rod DeVille—a 60-watt 2x12 combo designed for portability and power.

Hi Jeff,
First of all, let me say I really enjoy reading your column every month in the best guitar magazine on the market. I need to know how to “tame” my Fender DeVille—it is the loudest 60-watt amp I’ve ever heard and I’m not wild about the overdrive channel. I can never get my volume past 2 before everyone is yelling for me to turn it down. I’ve thought about replacing the 6L6s with 6V6s, but what I’d really like to do is put some KT66s in place of the 6L6s. (Of course, that won’t help me tame the output at all.) Can you suggest any mods I can have done to help me with this problem?

From one Jeff to another, thanks and keep the great articles coming every month!
—J. Jeff Bissette


Hi Jeff,
Thanks for being an avid reader of Premier Guitar and my column. Glad you enjoy the topics.

The DeVille series is probably the most successful in Fender’s product line and the amps came in two incarnations: the earlier offering, the Blues DeVille, and the later version, the Hot Rod DeVille. The “updated” version was given more drive in the overdrive channel by tapping into an unused half of a 12AX7 preamp tube (V2B) in the Blues DeVille design.

On the surface this may seem like a good idea—make full use of a component that is already installed and give more gain to an amp whose predecessor may not have had enough overdrive to satisfy some rockers. While the result may have worked for some, it’s obvious by your comment that it did not work for you, and I don’t think you’re alone. To me, this is an example of “just because you can doesn’t mean you should.” Maybe this idea could have been executed differently, but in my opinion, the way the extra stage was implemented in these amps results in a drive channel that’s very “grainy” and not as musical as I’d like. You probably feel the same way.

Now I could just tell you to have your tech remove R 20 and R 25 and connect the signal input end of C 10 to pin 13 of K2B—but I won’t. In theory, this would bypass the new circuitry associated with V2B, but there have been a substantial number of other circuit changes compared to the Blues DeVille, so I’m not sure the remaining Hot Rod circuit would be satisfactory enough to be worth the modification. At some point I may have the opportunity to perform this mod and I’d be very curious to hear the results. But for now, let’s see if I can give you a few real-world suggestions to improve your amp.

Let’s first address your dislike of the drive channel. I’d suggest trying different types of preamp tubes, particularly in the V2 position. Changing the gain structure in the amp with alternate tubes could possibly result in a more musical drive channel. Since it’s the most readily available, you might first try installing a 12AT7 in the V2 position. This will reduce the gain in the last two stages of the amp prior to the phase inverter, but know that it will affect the clean channel as well, so you may need to raise the typical setting of your clean volume control.

If this doesn’t yield acceptable results or you would just like to get more adventurous, try both an ECC 832 and ECC 823 in the V2 position. Each of these tubes has one half equivalent to a 12AX7 and the other half equivalent to a 12AU7, but they are mirror images of each other. This means that each one will reduce the gain in the opposite stage than the other and only one, as a matter of fact, will affect the clean channel. Hopefully one of these tubes will yield a better-sounding drive channel.

Let’s move on to taming the amp’s volume. Installing 6V6 output tubes in this amp is not something I’d recommend. The plate voltages typically used with 6L6 output tubes would be a bit too high to use with most 6V6 output tubes. That coupled with the fact that the primary impedance of the output transformer is more than likely lower than what is recommended for 6V6s, I’d caution against it. And of course KT66s, being similar to 6L6s, won’t result in any significant power reduction.

One quick thing you might want to try is installing a 12AT7 in the phase inverter (V3) position. It won’t reduce the amp’s output power, but it will reduce the signal feeding the output tubes and may give you more control with the master volume. As far as reducing the power that’s reaching the speaker, there are a couple of ways to accomplish this. One is to use a power attenuation device of some sort, such as a THD Hot Plate, Tube Amp Doctor Silencer, Rivera RockCrusher, Tone King Ironman, Dr. Z Air Brake, and Alessandro Muzzle. Inserted between the output of the amp and the speaker, these devices allow you to adjust your amp to the settings that sound and feel the best, and then attenuate the amount of power being sent to the speaker. This lets you control the overall volume. Some players get creative and mount these devices in the back of their combo, so the unit is always connected and ready to go.

Another way to reduce the output power of your amp is to use a device called a Yellow Jacket, which is designed by THD Electronics. These adaptors plug into the output sockets of your amplifier and convert the output tubes from the current 6L6s to EL84s. Doing this will reduce the output power of your amp from 60 watts to approximately 20-30 watts. This should provide a much more manageable power for smaller venues. However, this will also change the amp’s sound. While 6L6s have an open, glassy tone, EL84s tend to be more compressed with a bit more midrange and less highs. Depending on what you’re looking for, this could actually be an added benefit.

Well, there you have it—some simple, player-friendly possibilities to tame your amp. I hope one of them helps make your DeVille divine.


Jeff Bober is one of the godfathers of the low-wattage amp revolution, co-founded and was the principal designer for Budda Amplification. Jeff recently launched EAST Amplification, and he can be reached at pgampman@gmail.com.

     

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Comments

(6 comments) display by
UsernameComment
Shawn
4 hr 9 min ago
what about just wiring the speakers in series for a 16 ohm load and thus reducing the efficiency and output. this should drop the output volume as well, right?
jamminfool
on 04/08/2013
@ JoJo...you're right about the linear taper pot in the master volume position...I just recently had an audio taper pot installed, along with swapping out the pc-mounted inputs (#1 broke clean off the board, #2 was on its way) for hard wired replacements. The audio taper, while it does not reduce the overall volume and ferocity of this amp (especially in more drive...I've found the regular drive channel to be very nice, right along the lines of the Blues Deville), it makes it somewhat easier to dial in a more usable volume level before you hit 2...which seems to be the original question along with how to tame the grind in the drive channel! I now have a master volume that allows me to make gradual adjustments between 0 and 5 before it gets to ear splitting, mind numbing, all out Fender ferocity...a state I find to be blissful btw! My minor mods, along with general servicing (which my amp needed as it is a '98 model) ran me $140 total...not bad, considering my other option was to sell my favorite rock and roll amp and buy something with a single speaker in it, and much less power...which I still might do anyhow (sever case of G.A.S. lol), but now I get to keep my uber-Fender Hot Rod monster, and not get crap from everybody in the room when I crank it to that sweet spot!
Paul
on 02/19/2013
i have this amp and it is insanely loud..... i've done a couple of things that have worked will to "tame the beast". 1) plugged my strat into my ibanez ts9 and directly into the "power amp in" jack. this sounded great at bedroom level. 2) add a compressor in to the effects loop. this allows me to turn the preamp gain on the amp aka the "volume" to about 8 or 9 which gets the preamp section nearly into break-up and then i control the signal level going into the power section using the volume on the compressor (i used a bbe opto stop for this which sounded great) 3) i went to the electronics store and bought a 50k pot and put it into the effects loop (i wired the pot into a small box with 1/4" jacks to do this). this was the worst of the above two options since there was some loss in treble tone but requires no batteries which is nice if you want a foolproof back up. three good options that require no mods to the amp. still trying to solve the 50 pound weight of this thing though....
Ernesto Martinez
on 10/23/2012
Correction. I have a Blues Deluxe with this mod. I am assuming the procedure to be the same. These amps are in the same family. You would only drop the wattage on the hot rod deville to about 38 watts.
Ernesto Martinez
on 10/23/2012
Installing 6v6 tubes in this amp is possible but it has to be a JJ6v6s (about 22 watts). With a bias at 25 to 45mv it will take it and then some. This mod makes the tranny want a higher impedance as well. So the 8 ohm tap is now 16 and the 4 ohm tap is now 8. You wont harm anything if you do nothing about the impedance in this setup. The iron can take it. If you check the specs on these particular tubes you will see that I am right. I got one with this mod right now. Runs like a champ and purrs like a tiger.
JoJo
on 08/07/2012
Jeff Bober is the da man! I also heard that the volume knob on these amps is a linear taper pot vs. a audio taper pot? I know changing it will not reduce volume but I had wondered on these amps if an audio taper pot was installed it would at least give more gradual volume and more room to adjust between 1-2 instead of going full out loud so quick? Thoughts?



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