Fender Hot Rod Deluxe mods

*From the AMPAGE Tech-Talk BBS...*
HR Deluxe tone - What to do? Mon Mar 22 18:39	Tom

Hi Folks, I have a hot rod deluxe I thought I liked at one time. Now, the more I play it, the more I hate it. The clean channel is pretty decent sounding but the lead channel leaves something to be desired. It's kind of spattery and fuzzy, but not "nice" fuzzy. I'd like to keep the amount of drive the amp is capable of, but I'd like to shape it so it's smoother and not so harsh. Anybody have any ideas for "re-toning" this thing before I start tearing it completely apart? I'm not afraid of PCB. I'm willing to work with it. Any comments and suggestions are welcome and appreciated.

Re: HR Deluxe tone - What to do? Tue Mar 23 02:35 in reply to *Tom*	Steve A. steveahola@yahoo.com http://www.techaccessinc.com/blueguitar/

Tom: Most of the Fender amps come with schematics these days so if you have one and can scan it, maybe we can all take a look at it and give you some ideas... Steve Ahola

Re: HR Deluxe tone - What to do? Tue Mar 23 03:20 in reply to *Steve A.*	dave dhr@superlink.net

I've been through the ringer trying to get a good tone out of my Blues Deluxe. You can start by putting in decent NOS tubes and rebias. I got a great tone out of the clean channel using Phillips 6L6WGB's - kind of a fat 'early breakup' sound. I gave up on the drive channel and used a fuzz box in front of the clean channel. With all the poo-pooing of the Blues/HR line, I was very happy with this amp....until the PT blew unexpectedly. Good sound, but unreliable. Of course, i don't recommend this, but I ended raping the PCB, and rewiring it to a simple, single BF style channel - no reverb, no channel switching and no effects loop, but a nice clean pure fender tone.

Re: HR Deluxe tone - What to do? Tue Mar 23 16:00 in reply to *dave*	Tom

Dave - I have a duet of Svetlana 6L6 in there now. It was an improvement from the ones Fender put in. Not to mention the original bias setting: 18mA/tube. I know they do that to make the tubes last longer but, seriously!... Anyway, I rebiased @ 30mA and tone improved noticeably, but the "sputter" channel is driving me nuts! Unless I get some good tips from some pro on this site, I won't mind "raping" the PCB myself and convert to simple tweed or BF. Steve - Don't have a schem. perhaps someone on here might have one and could post. Thanks for your replies.

Re: HR Deluxe tone - What to do? Tue Mar 23 16:50 in reply to *Tom*	dave dhr@superlink.net

Tom, A guy posted on the Vintage Guitar - Amp BBS that he converted his BD to a tweed bandmaster circuit. He basically tossed out the PCB and installed a DIY board. I was thinking of trying this myself, using a 5E7 eyelet board from Weber for the circuit construction. The tricky part would be fitting the tube sockets on the oversized chassis holes once the PCB is gone. BTW, the PCB rape project that I did was not as easy as I thought it would be. The board mounted pots are a PAIN IN THE ASS to mess with. Dave

Re: HR Deluxe tone - What to do? Tue Mar 23 18:20 in reply to *dave*	Tom

I could get a Hoffman board (or make one from one of his schems) as well, although I didn't think about the big socket holes being left behind after wripping out the PCB. Maybe a metal plate running along the back of the chassis could cover up what's there and then new holes could be re-drilled. On the rape job: did you reuse the original pots? ...I know what you mean. I've dismantled the PCB before to replace some resistors to carbon comp type. It didn't make much of a difference, so I put the old ones back. Tom

Re: HR Deluxe tone - What to do? Tue Mar 23 21:28 in reply to *Tom*	dave dhr@superlink.net

I had to use new pots for some of it.. I tried to switch some around to get the right values but the small pots couldn't take the heat of my soldering iron. Also, some of the values just weren't right for what was doing. It was a pain fitting them in there with the circuit board, but I got them in there. I used the standard size pots instead of the small ones. I don't know if they still ave some, but Jameco (?)Electronics had octal sockets available with a wider metal base. Its supposably just wide enough to get them onto the chassis. I ordered some a few months ago for future use because I was told they're in short supply. Haven't really checked to see if they'd work yet, though. The stock fender 9 pin sockets are supposed to just fit on the chassis. The metal plate might be a good idea. I've done that before using sheet metal on an old radio chassis.

Re: HR Deluxe tone - What to do? Tue Mar 23 22:31 in reply to *Tom*	Steve A. steveahola@yahoo.com http://www.techaccessinc.com/blueguitar/

Quotes: Tom: ...but the lead channel leaves something to be desired. It's kind of spattery and fuzzy, but not "nice" fuzzy. Dave: I gave up on the drive channel and used a fuzz box in front of the clean channel. So what is it with the OD channels on the modern amps from Fender, Peavey, et al? Do they actually think that anybody really likes that tone? Practically everybody says that they like the Clean channel but that the OD channel really sucks! Maybe they are trying to get "endless sustain" and to hell with the tone... Steve Ahola P.S. As for pcb-mounted pots, I really lucked out on the Peavey Classic 50. I tried one of those tiny pots from an imported guitar and soldered it directly to the copper pads— and it happened to line up perfectly with the OEM pots!

Re: HR Deluxe tone - What to do? Wed Mar 24 15:13 in reply to *Steve A.*	Tom

I don't know about Peavey, but I understand that Fender has different Design Teams for each of their amplifier lines. How does a team of, let's say, 10 engineers know what 10,000 HR Deluxe buyers want in the tone of their amp? Just on this BBS, everyone has a somewhat different opinion on what the tone of an amp should be. Yeah, ok. You trek down to your Fender Dealer and try the thing out. When I take the amp home, it never sounds like it did at the store. Anyway, I'm going to try surgery on my PCB-loaded Hot Rod and start playing with the tone stack, coupling & cathode caps, maybe the plate loads... The reverb is decent so I'll probably go against "ripping the PCB completely out - at least for now.

Re: HR Deluxe tone - What to do? Wed Mar 24 16:24 in reply to *Tom*	Dave Stork dstork@ibm.net http://homepages.infoseek.com/~storkaudio

Tom, I'm sure it would be possible to improve the tone of the overdrive channel to some extent without major surgery. Simply adjusting the gain structure and other parameters would probably go a long way toward improving the tone. I have the schematic and have performed warranty repairs on scores of HR-series amps, and I'd be happy to offer some suggestions if you want them.

Re: HR Deluxe tone - What to do? Wed Mar 24 17:28 in reply to *Dave Stork*	Tom

Dave, I'm open to suggestions. Please throw some tips this way. The chassis is already on my bench. I plan on attacking it tonight.

Re: HR Deluxe tone - What to do? Wed Mar 24 19:39 in reply to *Tom*	Dave Stork dstork@ibm.net http://homepages.infoseek.com/~storkaudio

Well, I'm afraid I can't make that deadline. I stayed home today 'cause I wasn't feeling well. The schematic is at my shop, so I can't consult it till tomorrow at the earliest. Good luck in whatever you decide to do.

Re: HR Deluxe tone - What to do? Wed Mar 24 19:59 in reply to *Dave Stork*	Tom

Sorry to hear that, Dave. Hope you feel better soon. I'm in no rush. If you ever get the chance to share some of your wisdom on this, it'll be much appreciated.

Re: HR Deluxe tone - What to do? Wed Mar 24 16:53 in reply to *Tom*	Charlie Escher charliejane@gorge.net

Tom, I was a tech at the Fender factory for a brief stint. Any employee could take home any model amp for the weekend, and use it on a gig or whatever. You couldn't tell much about the amp playing it in the test room or on the assembly floor. The lead techs and engineers were always fishing for ideas, it was a very cool atmosphere in that respect. As far as what 10,000 buyers want, the company tended to stick to what they've always done best, the classic twang thing. That's pretty much a take it or leave it sound, but the OD thing is far more subjective (IMO). You're on the right track, maybe try playing with some different interstage voltage divider schemes too, I get a lot of good results using that approach. I haven't modded any Deluxes or DeVilles, but if you're OK with reworking PCB stuff (I do it all the time), it should work out fine.

Re: HR Deluxe tone - What to do? Wed Mar 24 17:34 in reply to *Charlie Escher*	Tom

Charlie, you're right: the classic twang thing is what they do best. But I'm convinced that I can also get great OD tones out of the same amp. I'll try a few things tonight and post the results back on here. Thanks for all your inputs!

Re: HR Deluxe schematic on-line! Thu Mar 25 09:24 in reply to *Tom*	Steve A. steveahola@yahoo.com http://www.techaccessinc.com/blueguitar/

Tom: Found a schematic for the preamp section in my mailbox tonight: http://www.techaccessinc.com/blueguitar/hrdeluxe.gif :Different opinions on amps Maybe you'd agree that it could be possible (at least in theory) to design an amp that most of us would think is a really nice amp. For the OD channel, at higher gain settings you'd have all of the distortion and overdrive to please a metal head. At medium gain settings, the sound would clean up a bit to satisfy the hard rockers. And at lower gain settings (possibly using a 3rd channel) you'd have a nice overdrive for the blues players. The amp would be voiced so that you could put in darker or brighter output tubes to further fine-tune the tones. In gig-testing the amp with different preamp and output tubes, and at different control settings, they could probably come up with a very versatile design that would please a lot of people. Even if they couldn't design an amp that would please everybody, there are certain amps out there that most of us would at least respect even if it wasn't exactly our cup of tea. Like a Matchless amp- we all seem to think that they are overpriced, but you'd have to be pretty bull-headed to say that it was a "lousy" amp. Steve Ahola P.S. Looking at the HRD schematic, there are a lot of tricks you could try. I think that the 47uF Ck cap on the first preamp stage is a bit high; if you can add a switch somewhere, I'd wire it so that you could have 22uF, 0uF, or 0.68uF. The 1.5nF cap that splits the signal between the two channels could be replaced with something like a 0.01uF or 0.022uF Orange Drop for a fuller and stronger sound. For the second preamp stage, get rid of the "bright" cap on the cathode and stick in something like a 0.68uF or 1.0uF mylar cap (hard wiring the switch to ground so that it would be active in the OD mode). If that gives you too much gain, try inserting a 470 to 4k7 resistor between the Ck cap and ground. The tone stack looks a bit bit unusual- I'd try BF-ing it with a smaller slope resistor (like 82k or maybe even 68k) and possibly raise the treble cap to a 330pF mica cap. I like changing out the bass and mid caps with a high quality cap like a Sprague Orange Drop; you might try changing them both to 0.022uF or 0.033uF. The 390pF "bright" cap on the MV looks a bit excessive- you might try something smaller like a 47pF. (I have to pass on the "More Drive" circuitry with the two FETS's; I don't have any idea what that is supposed to do.) Good luck!

Re: HR Deluxe schematic on-line! Thu Mar 25 15:20 in reply to *Steve A.*	Tom

Steve: Thanks for the Schem., anyway, last night I couldn’t resist the temptation, so I started fooling around with this thing and here’s the rundown: I replaced the 47uF cap on the first preamp stage with a .68uF. I replaced all coupling caps outright with orange drops of the same value. I replaced plate (100K) and input grid (68K) resistors with carbon comps of same value. On the tone stack I replaced the treble cap to silver mica 470pF, replaced bass and treble caps to .022 orange drops and the slope resistor to 68K (really wanted 56K but didn’t have one). In the PI and power amp I replaced all the ‘stock mylars” with Sprague orange drops, as well. Well, I think I’ve improved the overdrive tone a whole lot. The tone got warmer and it has more definition at low AND high volume. That 47uF Kcap was definitely overkill - especially in drive mode. It seems the orange drops really cleaned up the tone as compared to the factory stuff. Also, opposed to what many think of the carbon comp, I think they play a key role in certain locations in the circuit. I’m going back in tonight to tweak a bit more. I’ll experiment with the 1.5nF off the 1st stage plate and the 390pF on the Mst Vol. as you suggested. I’ll post the results after I’m done. Sorry, this is a bit long. Thanks for your input.

Re: HR Deluxe schematic on-line! Fri Mar 26 03:17 in reply to *Tom*	Steve A. steveahola@yahoo.com http://www.techaccessinc.com/blueguitar/

Tom: Sounds great! I just wanted to mention that you ought to try a lot of different combinations of tubes to evaluate your mods so far. When you are "almost there" sometimes the different tone, response and gain of a specific tube will get you exactly what you are looking for. Steve Ahola My favorite 6L6's: Svets and Sovteks My favorite 12AX7's: Sovtek 12AX7WXT+ . . . . . . .Initial preamp Sovtek 12AX7WB . . . . . . . .Second preamp Yugo EI 12AX7. . . . . . . . .Initial preamp Ruby Tubes 7025STR . . . . . .Driver/PI GT ECC83 (possibly Tesla). . .Initial preamp GT 12AX7 = NOS GE 12AX7WA. . .Driver/PI

Re: HR Deluxe schematic on-line! Fri Mar 26 04:40 in reply to *Steve A.*	Charlie Escher charliejane@gorge.net

I have to pass on the "More Drive" circuitry with the two FETS's; I don't have any idea what that is supposed to do Looks like the FETs just shunt the 100K resistors to bring the Ck caps into play, seems like you could play with those Ck values to good effect in the More Drive ckt. without changing the clean sound much at all. Thanks for the schemo Steve, the boys at the shop lost the one in our floor stock HR Deluxe. --C.E.

Re: HR Deluxe tone - What to do? Wed Mar 24 18:17 in reply to *Steve A.*	Steve M. pentode@qadas.com

Steve A.: Just a thought, but it seems to me that most amp companies that mass produce amps (Fender, Peavey, Crate, SLM, and even Marshall to a certain extent) seem to make amps so that they sound "good" at low volumes on the showroom floor, but quickly reveal their limitations when pushed hard at a gig or at home, etc. Also some of these amps are aimed at beginners who are easily impressed by massive amounts of gain, whether or not it is usable is an entirely different story. The problem is that when an amp is designed so the largest number of people like the sound, it is so generic sounding that it only sounds marginally good to everyone, but doesn't sound killer to anyone. Steve M.