Name: Tim C. E-Mail: tcowles@cableone.net Date/Time: 8/29/99 3:32 AM Subject: Re: Modding Blues DeVille to a Hotrod Deville To whomever is interested, I don't want to step on Ed's toes since he is also going to share his mod but I thought I would share mine as well if no one minds. I have done this mod to several DeVilles for pro musicians who play the circuit night after night in Omaha and Sioux City. It is simple and will result in increased gain and dynamic response. Here goes. Change C1 from 25 mfd to 1 mfd at 50v. Add a .68 mfd at 50v electrolytic in parallel with R10. Change R11 slope resistor from 100K to 47K 1/2 watt. Change C6 from .1 mfd to .022 mfd @630v. Change C25 and C26 from .1 mfd to .033 mfd at 630v. Now here is the super secret! Remove C22 from the presence circuit and replace it with a straight wire. You now have a type of resonence control instead of a presence control. As you turn up the presence the gain increases and the tone becomes fuller and looser(spongey). KEEP THE TWEED BLUES DEVILLE!! Many now prefer it over the Hotrod version. I can send you the schematic with the layout and highlight the component locations if you want. I can walk you through the removal of the circuit board if necessary. The first time removing the board was a nightmare for me but after that it was easy. Sorry thia was so long. Let me know what you think. Tim C., Mr. Tube Amp Repair * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Name: Steve A. E-Mail: steveahola@worldnet.att.net Date/Time: 8/29/99 8:09 AM Subject: Re: Modding Blues DeVille to a Hotrod Deville Tim: Glad to hear of a pro shop that takes the time to develop and implement mods for these "pcb nightmare amps" that everybody is making these days! I saved a copy of your post to disk and if its okay with you I'd like to add it to my site (right next to the schematic and layout drawing for this amp). Let me know if it's ok, and whether you'd like me to change your e-mail address or whatever (you can add in an ad for your shop if you'd like). That mod to the presence circuit sounds interesting! Your idea may work well in other amps as well. (I'd probably add a switch to select between the stock pc and your modded control.) Thanks! Steve Ahola * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Name: Tim C. E-Mail: tcowles@cableone.net Date/Time: 8/30/99 3:07 AM Subject: Re: Modding Blues DeVille to a Hotrod Deville Steve, You may do whatever you like with the information I shared. I originally developed that mod for a good friend that was the manager of our local Fender dealer. He had a Blues Deville that he thought didn't have enough overdrive. After I modded it he liked the way it came out so well that he bought another DeVille and had me mod it the same way. Since then I have done several DeVilles that way. The same type mod can be done to the Blues Deluxe as well. I have also done several of them. The most satisfaction I get from modding amps is not the money but the smiles on customers faces afterward. By the way Steve, many thanks for helping me get my Telecaster 4 way switch working!!! I was about to give up on it. Respectfully submitted, Tim C. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Name: Bruce E-Mail: Missionamp@aol.com Date/Time: 8/30/99 1:44 AM Subject: Re: Modding Blues DeVille to a Hotrod Deville I think shorting the cap changes how much of the negative FB is sent to ground at ALL frequencies instead of to the phase inverter. That sounds like a form of variable FB and some variable PI gain control. The presence control is doing the same thing too, but since the FB is held from ground with the pot's resistive value, there is more NFB applied to the PI. With a cap to ground through the wiper acting as a shunt around the pot's resistance, it acts as an RC circuit and thus, frequency selective too. With no cap and the wiper connected to the grounded end, it acts just like a variable resistor instead of a pot. The long tail pair PI with a presence control is held above ground by the 2.5K to 5K resistance and this mod now bypasses that too. That means a litle more gain through the PI/Driver when the resistance is very low and at the same time less neagtive FB voltage to the PI. A bigger value cap will do a similar thing and you still get a little of the presence control. Bruce * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Name: Joe Movich E-Mail: jmovich@msn.com Date/Time: 8/28/99 12:43 AM Subject: Re: Modding Blues DeVille to a Hotrod Deville Scott, I have a Blues Deluxe, I changed the bright switch (which hardly added any highs) to switch in a cathode bypass capacitor on the second tube stage, basically like Fender's "Fat switch". This doesn't give a real lot of additional gain but it might be enough. You can tailor the response if you like by trying different value capacitors. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * ALTERNATE MOD from E.G. received 9/7/99 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * HI steve, I am going try again, after having already typed every thing once, to have the computer go poop, and lost my entire message. Oh well, here we go again! starting with C1 , cathode bypass cap 22uf to a .47uf, C2 coupling cap to a .0047 or the .01 ( to user's taste) C3 750pf to 680pf (Iused a silver mica), R6 100K to 220K,Replaced C4 750pf, with jumper wire omiting the 750pf, R8 (Grid grounding res.?)with a trim pot, I don't remember value other than the it was tweeked to 20k ohms. (200K would give the user a good area to play with) 20k seemed to keep things from getting too buzzy. At R10 added a 4.7uf in parallel to 1.5k cathode bypass. Then after C9 right after V2A, I pulled the 330K res. and put in it's place a 2.2 meg with a 10 pf silver mica in parallel, then using the 330K res., for the grid grounding of V2B. As you know this stage has pins 6,7 and 8 tied together, so I then got out my scalpal and cut the traces so that this stage could now be used. A 100K plate res., pin 6, a 1.5K and a 15uf paralleled from pin 8,to ground. (cathodebypass) At pin 6 (plate) I added a .1 Orange drop with a 220K C.C. res. in series from there to R21 Master vol. with a 330K from the top of pot to ground, to balance the level better. In the feedback loop, I changed R93 68K to 100K paralleled witha .01uf orangedrop cap. this seemed to be warm fat and smooth without being harsh sounding. CP3 B+ red wire has a 250 ohm (don't laugh) 50 watt wire wound with aluminum finned res. This res. made the voltage drop somewhere 20 to 30 volts, and we both felt that it made for a sweeter top end not so transient or piercing, like a solid state amp does. I also added a 4007 diode in series at X after the 10K res. That seemed to give a better articulation in the preamp. I also added a bias pot and this amp really sings. I think that is about it, if you have any questions or find any mistakes, please let me know. thank you very much, you have been so helpful, and the ampage is Great too . talk to you soon. P.S. If you need the schematic let me know, I don't know, I hope I explained this info clearly. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *