Mine's from the 2002 rev. and it has some value changes too. But I think you only have to recalculate a R value from the proposed changes.
Printable View
Mine's from the 2002 rev. and it has some value changes too. But I think you only have to recalculate a R value from the proposed changes.
OK, I got home from work today and the parts I ordered were here.
So I got right to making the mods.
Added 1nF in parallel to C11 for a total of 1.390nF
Replaced C1 with 22uF
Added 180k in parallel to R9 for 100k
(cut R103 a few days earlier)
This really made a big improvment and the drive channel is pretty deacent now.
I was planning on adding 3.2nF in parallel to C23 but the existing cap was installed all the way down to the insulation with no room for me to jumper anything on. The legs were snipped way to short to try to pull it away from the board. I'll have to totally replace it to a 4.7nF but I didn't order that cap.
Thanks everyone for the great thread and the help.
I'm a bit confused by what you say Falco, I explain why:
The best improvement you made is C1 lowered to 22uF, it's a typical fender Anode tube biasing...
having R9 fixed at 100kOhms is to block hum in clean channel 'cos 72 Hertz is the high-pass
filter frequency (assuming you didn't do a change at C10 value). Well, why not, but it's for the clean channel!
regarding C11, it forms a low-pass filter with the master potentiometer. So at first sight and if i'm not wrong, it's calculated frequency made by fender was 4080 Hz. It means it let frequency pass to the next stage,from close to zero Herts up to 4080 Hz which (to my point of view helps cutting a ripple in the eminence legend 125 speaker's respons-curve)
So why change that C11 value to lower the cutt-off frequency of that low-pass filter ?
Is it to make the drive channel darker, with more bass ?
I need explanations, I want to mod my amp but that C11 value is critical beacause it's close to the power-amp section....
Thanks for your answers.
Regards.
Largol.
Got the answer to my question, it's to tame that high chimey drive sound! I should have read the whole posts....
Glad I could help, lol.
I'm waiting for the components to do it. I'm going to try the "Y" with the trimers and de cap too.
It was said before in the thread that changing C23 value may cause intermodulation distortion, isn't it? So I would leave the original value.
I think the initial mod at C23 stated was to increase to 10nF, this was too large. A smaller increase say to 4.7nF was suggested, this is also the mod listed at the Unofficial Hod Rod Deluxe web page.
My amp's overdrive may be sounding good enough now that I won't change C23.
I have two Hot Rods and I have been tweaking them ever since i got them about 3 months ago. I'm a frustrated EE and was looking for a project. I began by buying the HRDX from some guy in Bakersfield CA on Ebay. He said it did not work. I played it for about 3 hours before it finally crapped out. I hung out on Jason's site and did every mod but the input jacks. I replaced all the signal caps with Orangedrops and beefed the thing with all of Jason's wisdom. While playing it, it crapped out again. I opened it up to find one of the zener diodes (16v) actually heated up from R77/78 nearby on the circuit board and popped off the board! Hot enough to soften solder. When it did, the voltage (wrong polarity) hit the 8 pin dip chips and burned them up.
I ordered new zeners, and dip chips then devised an off PC board R77/78 mod. I remote mounted 50W resistors (bought from Mouser) on a piece of aluminum angle (bought at Home Depot). The mod is perfect, no trouble ever since. I read a lot of people concerned about noise but not a sound, even at gig levels. These stock 5W resistors are a major cause for these amps hitting the dumpster. They put so much heat on the PC board that they turn black. Fender really cheaped out on the 16V circuit. This is a simple mod. If anyone is interested, let me know.
I have a 4X10 DeVille that i bought with a road case for $200. It also has issues! I will do the R77/78 mod on this one next.
Just bought a 65 DRRI on craigslist. It is sweet! It works so i need another project?
Sounds like a kit-build is in your future! :DQuote:
Originally Posted by stzomah
Am I the only one who thinks any mod to these amps short of gutting the chassis and building in a good circuit is like putting lipstick on a pig?
...cue the horse in the cape...
Quote:
Originally Posted by 121064
no - your probably not.
But no need to kill a good thread that is allowing some peole to get and share information that is helpful for them. No need to do the "Dog pile on the rabbit " bit.
This has been an interesting an informative HRD thread.
But in the end, a rebuild is usually in order. It's just the PCBs...they can't handle repeated mods.
I discover my amp is a "2nd" revision schematic, dating from year 2002.
It was checked and approved the 19 september
2002.
It leads me to change my mods. I have done the master volume mod: 250k pot log, R25=142kOhm, C10 remains the same, C11=150pF, so i don't change roll-off frequency , I might had like a lot of forumer a 1 nF in // to C11.
So the main difference with 1st rev of the amp (schematic from year 1995) is the incerased value of R9=270k (instead of 220k), R52=240k (instead of 180k), C23 and
C18 remains unchanged....
The normal/bright switch applies to tube V2-A and not V1-B like in 1995 amps...
It means that the bright switch is applied after the tone stack and not before like in older version of the amp!!
Does that revision matters concerning the bright switch ?
any comments or ideas ?
By the way I lowered C1 and C56 to 22uF instead of 47uF. It's much more a traditional Fender value for biasing correctly cathod.
Best regards.
Largol.
I've just made some of the mods and I have to say I can't believe this amp could sound so good!
I changed C1 to 22uf and R9 to 100k and the clean channel is awesome! Now it really sounds like a Fender, very close to a Deluxe Reverb, but I feel it with more body. I tried a low gain tube in V1, but I like a 7025 on V1 lowering the gain with C1.
For the Drive channel I tried the C11 mod with 1nF and 1,5nF and fixed it a bit but still wasn't a good overdrive sound and the More Drive wasn't good at all to my ears. But the trimmers mod ²Thom suggested works great! You can eq the drive channels to sound really good both! And you can get a clean sound very very close to the clean channel rolling back the volume. I couldn't believe it when I heard it!
Now I don't need overdrive pedals anymore! Believe me! Just try!
Thank you very much Giulio and ²Thom for that mods!
I have to say that I play my hot rod almost every day for more than 2 years and not a single problem!
I'm glad it worked for you as well!Quote:
Originally Posted by Alcaraz
Giulio
I'm really confused on what to add to my lovely amp.
had trouble to understand how to do the Y modification.
And why adding a 5,6nF in // to R24, what's the exact purpose?
thanks.
Largol.
I can mod as far sa I want I just bought a special liquid to make again the copper foil, delaminated from PCB!
No need to have a turret board, NT Blues Guitar :p)
What fun is that, then?Quote:
Originally Posted by Largol
:D
I found a special liquid that is conducting electrons, replacing copper foils when damaged!
I'm done with the mods :)
I have done the Y surrounding R45, modified C1 all along C56 22uF, did the master volume mod I.e. R25=142 Ohm, C10 unchanged, C11=150pF, R26 pot 250k Audio.
I added the 5,6nF // to R24.
and i sounds good to my ears, hummm tasty!
I didn't changed the clean channel (R9!) because I already liked it that way.
I didn't do the mods of brightness suggested at the unofficial HRDX page, by Justin Holton, cos I like my bright switch!
I did change all cathod resistors 100k metal film 1/2 watts, even R57 and R58.
changed the jacks for switchcraft like, get rid of that chinese jacks!
No, I'm off to do the cooking for the familly and tonight I play the blues in 12 bars, babe!
Yeeahhh!
It was a long process and involved a few volume drops, voltage checks (beware, one had in your pocket!) but I'm done and satisfied.
Thanks to shrededge, 2Thom, NT Bluesguitar (the 330Ohm!), as well as Alcazar!
I'm glad you got it too! But I think that if you do the Y with trimpots on R45, you don't need to change C11. I tried, just C11, just the trimpots and both and liked the trimpots.
What's the master mod R25?
can any of these mods work on a hot rod deville? or is that a completely different animal?Quote:
Originally Posted by shredgd
Sure they can, the hot rod deville only differs in the power amp section (20W more) and number of speakers.
Giulio
The power transformer and output transformers are different. The bias taps are totally different and have a different voltage they supply. There are different filter caps in there, too.Quote:
Originally Posted by shredgd
But, other than that, the rest of the circuit board is the same.
Sheesh!
It aint rocket surgery guys !
Great work!!! and great ideas!!!, but it seems that some of these things venture into flat out rebuilding rather than mods. Seems like the long way around the lake, to get point to point performance, when used and clean point to point products are readily available. This all seems to miss the intended price point of this amp--- But sincere congrats to all on these mods because they all seem worth it in a tone sense if not a financial/time sense.
With that said you guys are very good if not great at what you do!!!! And I'd love to hear the results in a live playing setting with a favorite guitar. I'm not sold until I hear it live.
Well, yes, and no, and such. I didn't just up and re-build mine because I felt like it. The PCB went the way of the dodo (albeit expectedly). And my circuit was not a simple drop-in, it was the best match for tube complement, wattage, speaker, and it was designed around the remaining Hot Rod components.Quote:
Originally Posted by 1958lpjr
Rebuilding it cost me MUCH less than a kit or new amp would, and I got the hand-wired quality in the end. It's built like a tank now. I came out way ahead, as I figure it, even with the initial amp purchase.
Taken in that context your work and all of the above is warranted, respected and I get it. It is very obvious you know your electronic facts.
But the trend on the threads seems to be trashing a decent amp (price vs performance), built for a price point and a receptive market and unfavorably comparing it to a Trainwreck or a Z (where price isn't the issue) or whatever the poster hears and sees as the ideal tone, and build.
These amps aren't meant to compete with the high end,and they aren't meant to be heirlooms either. But they do provide a pretty good serving of Fender tones for the masses, and if you treat them right and have good touch they sound pretty good.
By the way GREAT!!! looking rebuild work!!!
:applaudit
Thanks!
I agree about the price points. And, honestly, considering the lower price point, it's just about the perfect platform to do this kind of stuff on.
Thanks NTBlues,
It's refreshing to hear someone sensibly describe these matters. I wonder how many of these mods are done in response to problems encountered after playing in a variety of actual playing situations, as opposed to the need to correct poor construction practice from the factory, or just for fun and the challenge.
For instance I've had pedals, amps and guitars sound wonderful in my living room--free of any offending issues, and on the job it doesn't cut it because the the sound is to clinical,or clean, or it lacks any distinct charachter or voice.
Where I disagree with alot of the HRD bashing, is that , when used in a band or possibly a recording setting, I think these amps are voiced pretty well from the factory. ( yes the drive channel is noisy, so are about ten thousand other amp and OD pedals) But with that said it sounds pretty sweet with a 58 jr through a PA in a crowded bar every saturday.
Most working musicians use this amp in large rooms, bars whatever, with noise floors exceeding the worst designed amps in the universe----so I wonder about engineering out
.005 db of whatever
I think the variables of guitar type, cable type, effect chain, player ability, and the art of playing with players that listen to each other seems to be completely left out of the story. The whole load gets dumped on the HRD. Issues of heat from tubes excepted.
Sorry about ranting!!!
Question for NTBlues: In your November 23, 2007 post you included a nice picture of your HRD in its original/modified form. I noticed that you added a cap in the C32 position that is normally empty on the stock HRD. What size cap is this and what part does it play in your modifications? Did you match the original Fender values for caps C36, C35, C33 and C31 with this mod?
Ah...okay, I see what you're asking about now.
I wanted to try Sprague Atoms, and they didn't come in the same values as the stock caps. So I upped them from 22uF to 30uF in all the stages after the first stage. The first stage calls for a 47uF cap, and here I paralleled a 20uF and 30uF to make that stage 50uF.
I was hoping for a bit extra in the filtering stage to help quiet some noise down. It wasn't really much of a change, but they were newer caps. The ICs in there were over 10 years old.
I would do it differently next time and just get some Xicons in there at stock.
I recommend you put your resources into the signal path components, unless you're in need of a cap job. The Spragues are just too expensive nowadays...they weren't when I did that work.
Thanks, NT. I believe these caps on my HRD are fine. Sometime back I reviewed a thread entitled "Tone caps for hotrod deluxe" and copied a picture of your original, modded HRD with a list of components you swapped out. These included C5, C6 and C7 for the tone stack, C2, C10, C11 and C23 prior to the phase inverter and phase inverter caps C24, C25, C26 and C27. Are these the caps that you refer to when you say "I recommend you put your resources into the signal path components, unless you're in need of a cap job"?
Those are the ones. I did a number of the mods from the Unofficial HRD site, too. Namely the brightness and 'better bass' mods.
If someone has done spice simulation of the Hot Rod Deluxe amp, I would be only to pleased to have the files....
Cheers everybody.
Largol.
I would do the Green Eagle Mod.
This is for you NT
[/url]http://i323.photobucket.com/albums/n...7/100_0362.jpg
Heh...you did do that mod. You did a pretty good job with that build, too. :headbangeQuote:
Originally Posted by LGS
Thanks for the kind words!
Really, no one made the simulations under spice ??
Please help me as I'm not considering a total rebuild.....
Why aren't you able to run your own simulations?