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Topic: Fender Tube Question |
Michael Pierce
From:
Madison, CT
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Posted 28 Jul 2008 11:42 am |
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To date, I have only used solid state amps for pedal steel (Peavey and Evans), but am curious to try a lower wattage vintage (or reissue) Fender tube amp. I think I've read every post on the Forum on the subject, and at least superficially understand their advantages and limitations.
My question is whether the lack of a "mid" adjustment is a significant hindrance to using one for pedal steel -- the amps I'm looking at (Bassman, Bandmaster and Deluxe Reverb) don't have one, but dialing out the "mids" seems to be a necessary adjustment for pedalers. Extra credit given for answers that won't tax the "electronically-challenged" like me!
Any recommendations on a low wattage tube amp? (I would likely only use this for playing at home so the lack of clean headroom found in the smaller versions not a huge deal -- just want to try that warm tube sound.) I currently have a line on a gently used 1968 Silverface Bandmaster at a reasonable price. Thanks, mjp |
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Jon Light
From:
Saugerties, NY
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Posted 28 Jul 2008 12:08 pm
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Here's my observation and experience re: the mids on a Fender-----I installed a mid pot on my SF Deluxe Reverb because....because I could. and because I believed that it was essential to have a mid control. It is in the ext. speaker jack in back---non-invasive.
After all sorts of playing around with the pot I found that the setting that sounds best is probably right where it would be if there were no pot. You see, a pot is just a resistor that you can vary. Stock, the DR has a standard, fixed resistor. So what I'm saying is that when I have it set to sound the best, I bet the pot would read out as the value of that fixed resistor (8K? I forget...)
No, on Fenders tube amps where the mid-range is already rather scooped out, you don't need to worry about major mid adjustments the way you do on the big SS rigs. I do like to have maximum eq control but in this case, in reference to the 'need' to dial out the mids, it shouldn't be a major concern.
That Bandmaster would likely work out real well for you. |
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David Doggett
From:
Bawl'mer, MD (formerly of MS, Nawluns, Gnashville, Knocksville, Lost Angeles, Bahsten. and Philly)
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Posted 28 Jul 2008 1:47 pm
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| I agree with Jon. I've tried lots of small Fenders with no mid control, and have always been able to dial in tone about as good as on the bigger ones with more tone controls. I've found the speaker size to be more important. I find the 10s in Champs, Princetons and Vibroluxes to be less steel friendly than the 12s in Blues Juniors and Deluxes. |
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Jonathan Shacklock
From:
London, UK
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Posted 28 Jul 2008 2:27 pm
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Michael, I hope someone will correct me if I'm wrong but having no mid pot is the same as having a mid pot and setting it on zero, which is more or less where you would have it anyway, as Jon says, to get the most out of that Fender mid-range scoop. On this diagram the blue line is the mid control set on 5. The biggest scoop is with the pot on on zero.
The bass control also affects the scoop, a higher setting giving you the deepest cut:
The treble has the side effect of shifting the mid point of the curve. So if you want to set the mid point to 800Hz you would put the treble somewhere around 2.
So no problem dialling out the mids with just two pots as long as you know how the controls interact.  |
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John Groover McDuffie
From:
LA California, USA
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Posted 28 Jul 2008 3:58 pm
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It is my understanding that on blackface and silver face Fender amps without a midrange control the circuit values are like having the midrange control set on about 7-8. There is a 6800 ohm resistor in place of the 10k midrange pot (wired as a rheostat) in the tone stack. That resistor could be changed to give more or less midrange.
I have a midrange knob added to the "steel" channel (also sounds good for acoustic guitar) in my hot-rodded S.F. Deluxe Reverb. (Thank you Bob Metzger!) It was mounted in the #2 input hole so no amp chassis were harmed. I do adjust it sometimes, but it is much more subtle than the bass and treble controls.
I also use a S.F. Pro Reverb without any "steel friendly" mods and don't suffer much for not having a midrange pot.
Last edited by John Groover McDuffie on 28 Jul 2008 6:09 pm; edited 1 time in total |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 28 Jul 2008 6:02 pm Re: Fender Tube Question
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| Michael Pierce wrote: |
| My question is whether the lack of a "mid" adjustment is a significant hindrance to using one for pedal steel -- the amps I'm looking at (Bassman, Bandmaster and Deluxe Reverb) don't have one, but dialing out the "mids" seems to be a necessary adjustment for pedalers. |
The only problem with having no mid control is that your tonal palette is severly limited. If you don't like the amp's voicing, you're kinda stuck (unless you make some component changes or use a stomp-EQ), since the voicing is controlled mainly in the mid-ranges.
If you're playing ELEN (easy-listening E9th), you can get by with low wattage amps. But if you're looking for fat tones at any volume (or C6th stuff), low-watt tube amps will leave you experiencing some distortion.
I have 4 great tube amps, but still reach for the solid-state ones 90% of the time. The differences are easily heard in a studio setting, but quickly disappear in a band situation, IMHO. |
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Twayn Williams
From:
Portland, OR
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Posted 28 Jul 2008 10:21 pm
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I like the Fender Princeton Recording Amp myself, though they're pretty spendy. I've had no luck with the new PRRI and steel though. I don't like the Fender Hot Rod series, I think they sound bad, but other folks swear by 'em, so who can tell??
_________________
Primitive Utility Steel |
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Jerry Dragon
From:
Gate City Va.
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Posted 28 Jul 2008 11:55 pm
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| On my super reverb ,a68,if you crank her up and turn all the tone controls down you hardly get any volume at all. You can then dial in your tone by adjusting the tone controls up. I haven't tried this for pedal steel but I use it on guitar all the time. I think most of the pre CBS circuitry of that era works alike in most of their amps, I could be wrong though, so don't quote me. My super is 45 watts, I think the pro reverb is also. |
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Jonathan Shacklock
From:
London, UK
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Posted 29 Jul 2008 1:26 am
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| John Groover McDuffie wrote: |
| It is my understanding that on blackface and silver face Fender amps without a midrange control the circuit values are like having the midrange control set on about 7-8. |
John, if that's the case then I've got my information totally wrong and the midrange control gives you a large amount of cut you wouldn't otherwise have. I don't mind being wrong but I can't find a source that confirms this one way or the other. My apologies if my post is incorrect. |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 29 Jul 2008 4:44 am
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| Quote: |
| ...the midrange control gives you a large amount of cut you wouldn't otherwise have. |
With all due respect...yes, exactly. Your ears will easily verify the additional scoop whenever you have a mid control. The tone controls in most Fenders are ALL passive. They can't add anything.
Therefore, the mid control can only cut, or reduce the amount of mids, it can't add them. |
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Jonathan Shacklock
From:
London, UK
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Posted 29 Jul 2008 5:56 am
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Hi Donny, I wasn't suggesting anything could be added, I was just under the impression that a mid range control allowed you to reduce the amount of mid range attenuation (as you turn it up) from more or less the same scooped starting point as a two-knob Fender amp.
| Quote: |
| Therefore, the mid control can only cut, or reduce the amount of mids, it can't add them. |
So does that mean setting a mid control on 10 is the same as a not having a mid control? |
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John Groover McDuffie
From:
LA California, USA
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Posted 29 Jul 2008 7:43 am
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| See my post above. |
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David Doggett
From:
Bawl'mer, MD (formerly of MS, Nawluns, Gnashville, Knocksville, Lost Angeles, Bahsten. and Philly)
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Posted 29 Jul 2008 9:25 am
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| Don't know the specs, but my ears agree with John. For pedal steel, I find the Fender mid scoop a bit too much. So my typical settings on my silver-face Pro Reverb or Dual Showman Reverb are with the mid on about 8, and treble and bass around 3. So it makes sense that when I try one of the smaller Fenders without a mid control, I don't really miss it. But, like Donny says, if you want more mid scoop than that, you can't get it without modding the amp. |
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David L. Donald
From:
Koh Samui Island, Thailand
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Posted 29 Jul 2008 10:12 am
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There is a simple mod that goes under the mid pot,
or replaces the mid resister,
with a pot or a resister and can replace the lost mids if you like.
A lot of techs can do it no problem.
Get the amp you like, I'd say a Deluxe with a 12"
if you want a lapsteely bluesy thing,
and have it mod'd. Takes 20-30 minutes.
_________________
DLD, Chili farmer. Plus bananas and papaya too.
Real happiness has no strings attached.
But pedal steels have many!
Last edited by David L. Donald on 30 Jul 2008 2:14 am; edited 1 time in total |
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Steve Feldman
From:
Central MA USA
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Posted 29 Jul 2008 10:30 am
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I thought those 68K grid stopper resistors are primarily there to pick up noise, etc., rather than to shape the tone. 
_________________
"...An admission of interest in protracted commentary is certainly no reason to capitalize on surmised aberations that do not exist." - BH |
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John Groover McDuffie
From:
LA California, USA
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Posted 29 Jul 2008 11:16 am
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We are talking about the 6800 ohm, or 6.8k resistor in the same place in the circuit where the midrange pot would be if there were one.
I don't know which resistors you are talking about, but the term "grid stopper" makes me think you are talking about something else - the 68k resistors that connect the inputs to the first stage preamp tubes perhaps? |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 29 Jul 2008 12:06 pm
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| Steve Feldman wrote: |
| I thought those 68K grid stopper resistors are primarily there to pick up noise, etc., rather than to shape the tone. |
The 68k grid-stoppers are at the input jacks. They serve multiple purposes. When using the 1st input jack, they parallel together thru the #2 jack-switch giving you a 34k grid stopper resistor to the tube. Having some grid stopping resistance helps reduce HF oscillations and RF interference. Then when you plug into jack #2, then you get a divider which pads the input signal, one 68k to ground, the other to the grid giving 68k of grid stopping. This input jack will load down most pickups TOO much and make them dark sounding. Then the 3rd function of that pair of resistors is to allow mixing of two instruments, one plugged into each jack. In that case, each instrument has its own 68k grid stopper, and the 1Meg resistor to ground sets the impedance. It's a clever little scheme. But those 68k carbon resistors are kind of noisy, and by changing them to metal film types, you can significantly reduce hiss noise.
And yes, those grid stoppers do affect the tone. They create a low-pass-filter as they interact with the tube's inherent capacitance (or miller capacitance). The higher the value of the grid stopper, the more highs you are cutting. But generally this cutting occurs pretty high up, like above 10kHz, so it's not obviously audible in most cases.
Then there's another clever configuration/modification of the input jack resistors and switching that Ron Wickersham at Alembic came up with. But that's another topic worthy of a different thread. In fact, this whole post here (so far) was kind of off topic.
Back to the midrange thing. A fender amp with NO midrange pot is NOT the same as taking an amp with the midrange pot and setting it on zero. Instead, it's more like setting the midrange pot somewhat high, like above 7. I personally like the midrange of the non-midrange-knob Fender amps, but it's true that you can't quite achieve that extra deep scoop of those amps with the mid knob. But that rarely bothers me when playing thru a Deluxe Reverb or Princeton Reverb. There's still plenty of "voice" happening.
Brad |
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Steve Feldman
From:
Central MA USA
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Posted 29 Jul 2008 12:13 pm
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| John Groover McDuffie wrote: |
We are talking about the 6800 ohm, or 6.8k resistor in the same place in the circuit where the midrange pot would be if there were one.
I don't know which resistors you are talking about, but the term "grid stopper" makes me think you are talking about something else - the 68k resistors that connect the inputs to the first stage preamp tubes perhaps? |
Yep - I was referring to the 68K resistors connecting the inputs to the first stage grid.
I don't see anything like what you're talking about on the Princeton and Vibrolux Rev schematics that I have access to. I'll ask around. Thanks.
_________________
"...An admission of interest in protracted commentary is certainly no reason to capitalize on surmised aberations that do not exist." - BH |
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Jonathan Shacklock
From:
London, UK
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Posted 29 Jul 2008 12:40 pm
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| Thanks for clearing up the midrange question guys, I stand corrected. |
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Steve Feldman
From:
Central MA USA
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Posted 29 Jul 2008 1:35 pm
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| Brad Sarno wrote: |
....
Back to the midrange thing. A fender amp with NO midrange pot is NOT the same as taking an amp with the midrange pot and setting it on zero. Instead, it's more like setting the midrange pot somewhat high, like above 7. I personally like the midrange of the non-midrange-knob Fender amps, but it's true that you can't quite achieve that extra deep scoop of those amps with the mid knob. But that rarely bothers me when playing thru a Deluxe Reverb or Princeton Reverb. There's still plenty of "voice" happening.
Brad |
Thanks for the info, Brad. One question: you say that a non-midrange Fender amp is like setting a midrange pot to ~7 (a high value). This implies lack of midrange scoop?? If so, then I don't get it. I've got a BF Vibrolux with no midrange pot and it is classic BF scooped tone. Perhaps I'm missing your meaning. Thanks.
_________________
"...An admission of interest in protracted commentary is certainly no reason to capitalize on surmised aberations that do not exist." - BH |
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David Doggett
From:
Bawl'mer, MD (formerly of MS, Nawluns, Gnashville, Knocksville, Lost Angeles, Bahsten. and Philly)
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Posted 29 Jul 2008 2:11 pm
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| Steve, if you get that Tonestack Calculator Jonathan is using, you can see that if the fixed mid resistor is like having the mid control around 8, there is no way to completely get rid of the mid scoop, even if you turn the bass and treble to 10. So on a Fender with no mid control, there is still going to be some mid scoop, no matter how you set the bass and treble. It's what Donny says, you will always have some mid scoop, but if you for some reason want a lot more than that, you need the mid control to really bring the mids way down. |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 29 Jul 2008 2:18 pm
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Steve, even with a high setting of a midrange knob, you still get a midrange scoop or dip. You'll never really get a midrange boost on that circuit, just less of a dip. Now if you turn your bass and treble down to 1, you can approach a mid boost, but really when dialing in any real tone setting, that mid will always dip at least a bit.
Take a Twin and put the bass and treble each on 4, and crank the mids to 10, and you'll still see a midrange dip. Not a sharp and deep one, but a gentle and round one, but it's still a dip.
Just like on your Vibrolux, if you have typical bass and treble settings, you'll still be getting a nice Fender mid dip. The amps with midrange control will allow for much more extreme and deep midrange scooping, but even if you don't deeply scoop, it's still Fender sounding.
Next time I get my Fender preamp circuits hooked up to some audio analysis, I'll try and take some screen shots to show this in action.
Basically what I'm saying is that all the BF and SF Fenders have a mid scoop to some degree. It's just that the ones with a Midrange control can scoop even more.
Brad |
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Steve Feldman
From:
Central MA USA
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Posted 29 Jul 2008 2:27 pm
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Okeedoke - I don't use the Vibrolux for steel at all - no interest. I think the amp is just phemomenal as it is - classic BF tone, and very interactive with the bass/treb.
Thanks all.
_________________
"...An admission of interest in protracted commentary is certainly no reason to capitalize on surmised aberations that do not exist." - BH |
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David L. Donald
From:
Koh Samui Island, Thailand
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Posted 30 Jul 2008 3:21 am
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Brad explained that all pretty well.
If you have an occilating high gain preamp tube, even farther in along the signal path you can add
a grid stopper right before the grid socket and it can help tame it.
I have a 7.8k right before my 4th stage in one amp.
If you have a 10k MID resister or pot you can add
a 25k-100k pot 'RAW Control' above it.
Or just replace it with a 250K pot.
A lot of people love this mod for this type of amp.
_________________
DLD, Chili farmer. Plus bananas and papaya too.
Real happiness has no strings attached.
But pedal steels have many! |
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Steve Feldman
From:
Central MA USA
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Posted 30 Jul 2008 6:42 am
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Just FYI, I've always been interested in this stuff - or what little I know about it. Been reading a few tube amp books and think I'm going to get a 5E3 (Tweed Deluxe) kit soon and put it together. Only vol and tone controls, but with full mids.
That should be interesting....
_________________
"...An admission of interest in protracted commentary is certainly no reason to capitalize on surmised aberations that do not exist." - BH |
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