Fender hot Rod Deville

[michael_krell]

I havent used this forum in a while. I know this isn't a stompbox related post, but I do have a question.

I just purchased a hot rod deville a couple months back in order to simplify my setup a bit. Does anyone know of any good mods for this amp? I want to start tinkering around with it, but i want to start with mods that are well known.

Thanks!!!

[GibsonGM]

http://studentweb.eku.edu/justin_holton/     

That site has every known mod for the Devile and Hot Rod Deluxe, plus a forum where you might get a ? answered.   I have a HRDx; I found it to be kind of shrill and cold (thought it was my guitar).  I think the Deville might be the same - after I did the mods, the thing warmed right up.  Esp. getting a good bias, the mid mod and cap changes!  In the end, I went to using pedals (hence my presensce here); for good old blues the amps are great, but anything modern really calls for DIY FX, IMO!  Save tube $ and use a nice OD pedal.  The HRDx and Deville are almost identical, and the info on Holton's site explains this.  Give it a read, and good luck...and watch those filter caps!!

~Mike 

[petemoore]

  B+ can be lethal, know your B+. Leave the drain resistor on while working, I use a stretch of electrical tape on a 10w 22k which begins smoking the tape if I power up...I figure it's better for the electrical tape than me or my resistor to smoke like that.

[Paul Marossy]

I did a few of my own mods to mine. You can read about them here: http://www.diyguitarist.com/GuitarAmps/Bluesdev.htm

[GibsonGM]

I drain my caps (all 5), check them with a DMM and then remove the jumper.  Leaving the jumper on even 1 time can fry the caps if you power up!  As well as other hard to replace stuff. It happens quickly (sounds like the voice of experience, doesn't it? ;o)       The caps in that line of amps don't hold much over 30V with the power switch and standy on with the plug pulled from the wall (of course).   Healthy and real respect is all ya need, in addition to full information about what you are dealing with. 

Read in the site linked above about draining caps - it's fully covered there and is specific to the Deville and Hot Rod Dlxe.   Not much anyone can add to that, I think.   

[Paul Marossy]

Just a word of warning - it's a real PITA getting the PCB out of the chassis.  Definitely not mod friendly like the old Fenders are.

[GibsonGM]

Yeah, this is true, Paul...you have to be careful, tilt the bottom towards the front of the amp and gently push down and pull the top out.  There's room for cracking the board or messing with a pot/channel switch.   Going slowly it's not too bad; I worry that I'll kink the little bus wires and eventually stress them to breaking point!    The mods were worth it, tho.

I like your fan idea, might incorporate that in mine!  Funny, I set my bias at 69mV by ear ;o)  Definitely cold from the factory!  I like a J&J 12AT7 in V1 for mine.

[erick4x4]

I did lots of mods to mine but honestly the biggest thing I did was buy a nice set of tubes and replaced the speakers.

All the circuit mods can help especially with the drive channel, but I really don't like those stock speakers. And so many tubes are better than the sovtek (GT) stuff they use. If you can find S.E.D.s or even some NOS stuff it really helps.

Still do the other stuff,  but know that if you really want to take the amp to a more pro level the tubes and speakers should really be done.

[Paul Marossy]

I thought about replacing the speakers at one time, but the stock Eminence speakers sound pretty darn good after being broken in well, so I decided against it! 

[Gilles C]

You can get some good info and some tubes to make it better sounding there.

http://www.eurotubes.com/euro-l.htm#2

https://ssl.eurotubes.com/cart/index.php?page=view_products&category_id=7&sub_category_id=32

Gilles

[SolderBoy]

Hotrod Deville...  I think that is the amp the guitarist in my band uses...  It has a very sensative vol pot.  I believe its a Lin pot.

You might try a log pot in there.  Won't really change the sound, but it will sure improve the functionality.

[R.G.]

A serious design mistake in the HRDV (and the earlier BDV) is the use of resistor/zener power supplies for the opamps.

I had to live with zeners in power applications for a few years. I do not remember them fondly. The failure rate is huge.

A much more reliable power supply for the innards of these amps is to replace the two power resistors with lower value but higher power resistors and replace the zeners with 7815/7915 three terminal regulators. The three-terminals have overtemp shut down, overcurrent limiting, and active regulation much better - and quieter - than a zener.

The power resistors are seriously undersized for the power they dissipate. Solder softens and melts at temperatures starting at 200+C. These resistors commonly cause their solder to soften and crystalize into cold joints which break; sometimes they melt the solder outright and it's been known for the resistor to simply fall out.

While the accountants may run the show at a big corp, it makes sense for a real human to replace the weak points in his amp. The resistors can be replaced or failing that, have a bent aluminum "U" bolted over their body to dissipate heat better. That will at least spread the heat into the air in the closed amp chassis and make the resistors cooler.

Power electronics designed by accountants does not work all that well.

[Paul Marossy]

The power resistors are seriously undersized for the power they dissipate. Solder softens and melts at temperatures starting at 200+C. These resistors commonly cause their solder to soften and crystalize into cold joints which break; sometimes they melt the solder outright and it's been known for the resistor to simply fall out.

I've heard lots of reports of problems with those power resistors. I haven't had any problems on mine, but that might be because I put a cooling fan in my amp. Your mention of the zener diode failure rate is a little unnerving, though! 

[nightingale]

Hi,
I am a certified fender tech [silver level]. I work on probably 6 or so hot rods per week. Not because there is anything seriously wrong with the amps,  I believe they are the best selling fender amps of all time. Most people's first tube amp is a hot rod or deville or deluxe.

RG is dead on the $ with his observations. 

Hope this helps,
ry

[GibsonGM]

Nightingale,

I'm looking at my HRDx schematic...do you know which R numbers are involved in R.G.'s mod idea?  Are these the zeners and resistors around the 4560 opamps - or could I assume all the 1/2 watters in there should be cooled?   I've met 4 or 5 ppl who also have a deluxe....2 in 5 have had the power resistors fail!  Fender says that was an issue related to parts supplies until something like 2002; I have my doubts, and now R.G.'s analysis makes me think I might want to put heat sinks on them - or at least to know which I should look at when mine starts cracklin'   
Thanks

Mike

[Ardric]

In section 4A of the schematic from blueguitar, R78 and R79 are the dropping resistors.  They are 470 ohm 5W.  CR13 and CR14 are the zeners; they're also 5W parts.