| Author |
Topic: Help with Hot Rod Deluxe Preamp Tubes |
David Higginbotham
From:
Lake Charles, Louisiana, USA
|
Posted 25 Jun 2006 6:38 pm |
|
I need some help from the "Tube Amp Masters." I have a Fender Hot Rod Deluxe and want to decrease the gain on the preamp tubes to give more head room. I have the schematic that I downloaded from the Fender website, but it doesn't tell me which tubes go to what. I want to go with 12AY7 or 12AU7 tube, but not sure which ones to change. Do I need to change all three or is there a specific one I need to change and which one? I also need a good source for the new tubes as well. Any help is greatly appreciated guys!
Thanks,
Dave |
|
|
 |
Jerry Erickson
From:
Atlanta,IL 61723
|
Posted 25 Jun 2006 8:30 pm
|
|
| Try one, try them all(the preamp tubes that is). |
|
|
|
Kevin Ruddell
From:
Toledo Ohio USA
|
Posted 26 Jun 2006 1:45 am
|
|
| the first preamp tube on the left of the tube arrray . is the one to try changing to a lower gain tube like the AY or AU. You can read more about this subjecct at the Torrres Engineering web site |
|
|
|
Tony Prior
From:
Charlotte NC
|
Posted 26 Jun 2006 2:21 am
|
|
try this site, very informative.
http://thetubestore.com/
I attempted swapping a few different tubes on my HR Deluxe with minimal success for the exact same reason, headroom.
I ended up swapping the amp for a HOT ROD DEVILLE !
problem solved.
The design of the amp is with the stock tubes, you can modify it somewhat by changing tubes, but headroom will not be the ony thing that changes. I found that by modifying the front end tubes on both HR Deluxe and Deville, it changed the overall characteristics of the amp , and not to my liking.
Stock tubes , 2-12's and 60 watts was the solution for me.
The website link above has some very good info regarding tube types and amp brands, as well as good pricing.
good luck
t |
|
|
|
Stephen Gambrell
From:
Over there
|
Posted 26 Jun 2006 2:26 am
|
|
I changed the first two, to 12AU7's---Good ol' JJ's, and it cleaned up my Blues Deluxe nicely.
Tony Prior is an old coot who doesn't know very much. |
|
|
|
David Higginbotham
From:
Lake Charles, Louisiana, USA
|
Posted 26 Jun 2006 5:20 pm
|
|
Guys, thanks for the help. I found out which tube to change and decided to try a 12AT7 and see how it goes.
Dave
P.S. Hey "Mutton Head!" Hope everything is fine on your end...
Dave |
|
|
|
Donny Hinson
From:
Glen Burnie, Md. U.S.A.
|
Posted 3 Jul 2006 1:34 pm
|
|
| Quote: |
| ...want to decrease the gain on the preamp tubes to give more head room. |
Decreasing gain anywhere normally means less headroom. A lower-gain tube may clean up the sound, but it does so at the expense of gain, usually...quite a bit of it.
At any rate, you can try a 12AY7, 12AU7, or 12BH7 if lower gain is what you really want. Thay're all medium-gain and have the same pinouts. A 12AT7 might not work much differently that the 12AX7, since it's gain factor is pretty much the same.[This message was edited by Donny Hinson on 03 July 2006 at 02:38 PM.] |
|
|
|
David Higginbotham
From:
Lake Charles, Louisiana, USA
|
Posted 3 Jul 2006 1:50 pm
|
|
Donny thanks for the info. I guess I may not have explained myself very well, but I was trying to get more volume before the amp starts to distort. After some research and pointers from fellow members, I decided to try a 12AT7 in place of one of the stock 12AX7 preamp tubes. I was told to change the one closest to the power tubes since it is the one that sends the last signal to the power tubes. This did accomplish what I had hoped and I am able to go somewhat higher on volume without the amp distorting. I am so impressed with the sound that I am now looking to go with a Hot Rod Deville for gigging with.
If I could have the sound of the Hot Rod Deluxe only with more head room it would definitely be my primary amp!
Dave |
|
|
|
Brad Sarno
From:
St. Louis, MO USA
|
Posted 3 Jul 2006 4:53 pm
|
|
David. I think that you're trying to do that trick that many have done with older Fender amps that have no master volume. First of all, the max power of the amp is just that, the maximum. You wont get any more clean headroom out of the power section of that amp. The reason people put a 12AY7 in the first preamp stage of say a Twin, is so that they can be sure that the power amp will max out before the preamp does. That makes sure the preamp section will not distort, and when you do hear any distoriton, it's gotta be the power tubes maxing out.
On your Hotrod Deluxe amp, it has a master volume control, so messing with different preamp tubes probably won't give you the clean headroom you're after. I'd suggest maxing out the master volume and then keep the preamp gain control low and clean. I may be wrong on this, but that's how I understand your situation. If you do this, and you get distortion, you can be pretty sure that you've reached the maximum output level of the amp.
Brad |
|
|
|
David Higginbotham
From:
Lake Charles, Louisiana, USA
|
Posted 3 Jul 2006 6:28 pm
|
|
Thanks Brad. That would be a correct discription of my goal. I was attempting to max out on the clean channel. The master volume is only operational on the drive channel, but I will try exactly as you stated and see how much more volume if any I can get.
Make no mistake tho, this amp has great tone is will work fine for home or small gigs. After tweaking the EQ and adding a little delay, I am very pleased with it. I found that by leaving it on the floor and tilting it upward greatly adds bottom end to the sound. Not so if I place it on an amp stand. Learn something new everyday I guess.
Thanks again for the help!
Dave |
|
|
|
John Lockney
From:
New Market, Maryland, USA
|
Posted 3 Jul 2006 7:21 pm
|
|
Check out this free book called the "Tube Primer" http://www.guitaramplifierblueprinting.com/index2.html
FWIW, I could hardly tell the difference between different pre-amp tubes until I installed a much more sensitive speaker.
Replacing the stock Eminence (which had a serrated cone to help it break-up earlier) with a Weber California (which has a rounded cone to prevent break-up) made a HUGE improvement. |
|
|
|
Brad Sarno
From:
St. Louis, MO USA
|
Posted 3 Jul 2006 7:25 pm
|
|
David, if your gain knob is your only volume control, then you may want to try a 12AY7 in that position. I don't know how they've balanced the pre and power sections to know which will clip first, but a 12AY7 would at least pull you in the direction of having the power amp clipping before the preamp does. Let us know what happens if you try it.
Brad
|
|
|
|
Jim Sliff
From:
Lawndale California, USA
|
Posted 3 Jul 2006 10:07 pm
|
|
FWIW the 12AT7 is not normally a "sonic" preamp tube; it has other uses. It's harsh and brittle when used as a "real" preamp tube.
The usual subs for a 12AX7 are 5751, 12AY7, or 12AU7 in order of decreasing gain. Normally, in BF or newer (including the Hot Rods) a 5751 is about as low as you can go and still drive the power section decently.
A 12AT7 would fall in between a 5751 and 12AY7 - but I would be surprised if it sounded decent - it would be pure luck at finding one out of a hundred particular 12AT7 tubes that worked in that application.
The 5751 is my favorite. Twin Reverb users trying to use the amp at low volume will benefit by using this tube in V2, although it still doesn't make a Twin a bedroom amp... |
|
|
|
Kevin Ruddell
From:
Toledo Ohio USA
|
Posted 5 Jul 2006 3:11 am
|
|
| my dos centavos ; ....I have a Peavey Classic 30 combo tube amp which is a guitar amp . I didn't know there were differences specifically designed for steel amps like the Peavey series. Starting out as a beginner I just would have bought a Nashville if I would have known . The pickup output from a Fender 1000, Dual 8 or Georgeboard lap seemed to be too much for the preamp stage to handle when picked hard, even around 3 and a half on the volume knob. I tried switching to a lower gain preamp tube and that didn't seem to be the answer; although a 12AU7 really smoothed out the sound of a Fender Pro Jr. I have. I didn't have any of these issues when when going through a separate preamp /solid state amp rig. What really solved the problem with the Classic 30 was first plugging into an ART vacuum tube compressor and then the Classic 30 .Although I can hardly tell it's on, and the threshold lights don't light up much while playing , it really stops the overdriving the preamp stage problem with the amp. The ART unit is a really smooth and musical sounding unit , and although I can hardly tell it's doing anything when in use , it's very apparent when it's out of the loop. It developed a problem last year that turned out to be a bad output jack, but the ART company repaired even though it was out of warrranty for almost 2 years. Prretty good support from this company. I replaced the stock Sovtek tube with a JJ Tesla [This message was edited by Kevin Ruddell on 06 July 2006 at 04:38 AM.] |
|
|
|
David Higginbotham
From:
Lake Charles, Louisiana, USA
|
Posted 5 Jul 2006 6:58 pm
|
|
Kevin that is a very interesting addition! Makes me wonder what Brad's box would do in that same application. I have used ART products in the past and been very happy.
My ultimate end result was that I replaced the Groove Tube preamp 12AX7 nearest the power tubes with a JJ/Tesla 12AT7. It has a cleaner & smoother tone with the ability to get somewhat more volume before distortion occurs. I tried to go back to the 12AX7 just to make sure I was hearing correctly and the sound was harsher sounding and I can't get as much clean volume. So, I personaly find the 12AT7 to be the answer and find it to be very musical. I could only assume that going with a 12AY7 or 12AU7 would help also, but I don't need to try it. I am now happy with the end result.
I appreciate all of the help and suggestions from those who took the time to write. This one can be closed.
Thanks,
Dave |
|
|
|
David Mason
From:
Cambridge, MD, USA
|
Posted 6 Jul 2006 12:31 am
|
|
| When I'm plugging my steel into any product designed for six-string and things aren't going well, I automatically cut the steel signal and everything cleans right up. I usually use either an MXR Dynacomp or an old DOD graphic equalizer stompbox, but the boxes aren't set to process the signal, except to lower the output - any old stompbox would do, that can cut output. An amp that is designed to be overdriven by a guitar pickup will usually get pretty freaky when you feed it 18 or 20 thousand ohms. |
|
|
|
