The sunn Forum
Sunn Musical Equipment => Q & A => Topic started by: foxfire on March 14, 2010, 08:45:58 pm
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i'm waiting on some parts for my 350L so started looking in to adding a MV. i've read a few posts suggesting just slapping a 1M pot in front of the PI and i've read a little on post PI MV's so i figured i'd ask for the pros and cons? also if i end up going with the pre PI MV is it right that i'd just ignore the mid boost and put the pot in right in front of the PI?
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You ought to be slapped for wanting to add a master volume. Get yourself a Marshall.
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Is that so...?
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You ought to be slapped for wanting to add a master volume. Get yourself a Marshall.
I agree with this 100%.
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well then i must be wrong! sorry for wasting everyone's time...
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I guess the real question that's on everyone's minds would be, "WHY WOULD YOU WANT TO DO THAT?!?!?!"
It's like adding a MV to any classic Sunn amp. It negates the purpose of the amp(or at least according to the opinion of most Sunn nerds -- and I'd have to agree), which is to have a pristine high fidelity signal. Yeah, you have to crank it to get break-up, but that's kind of what rules about it.
I guess most people are going to be appalled by this. I would imagine the actual tube distortion from the amp wouldn't even be worth the installation of the MV pot, though. I mean, wouldn't a tube distortion pedal be a far better investment?
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I guess the real question that's on everyone's minds would be, "WHY WOULD YOU WANT TO DO THAT?!?!?!"
It's like adding a MV to any classic Sunn amp. It negates the purpose of the amp(or at least according to the opinion of most Sunn nerds -- and I'd have to agree), which is to have a pristine high fidelity signal. Yeah, you have to crank it to get break-up, but that's kind of what rules about it.
I guess most people are going to be appalled by this. I would imagine the actual tube distortion from the amp wouldn't even be worth the installation of the MV pot, though. I mean, wouldn't a tube distortion pedal be a far better investment?
how dare you explain yourself and your position! i can't stand it when people who take the time to respond to a post actually have "something" to say and explain themselves.
anyway, this is partly why i'm asking, cause i don't know what a MV on one of these would sound like? i mean they put a MV on model T's and everyone seems to like them well enough. my sound city 120 has a factory installed master volume and it sounds good. and no i'm not saying a 1200 is a model T or a sound city 120. i didn't realize that i was the only guy out here that would like the idea of having a super loud amp that could do both clean and dirty sounds? i guess i should get a patent on the idea!
the other guitar player in my band uses a 50 watt head so cranking this thing isn't really an option. as for pedals, if i wanted to only use pedals i could've gotten a crate and saved a load of money. also if the amp can do what the pedal can do then why would you bother with the pedal?
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I guess the real question that's on everyone's minds would be, "WHY WOULD YOU WANT TO DO THAT?!?!?!"
It's like adding a MV to any classic Sunn amp. It negates the purpose of the amp(or at least according to the opinion of most Sunn nerds -- and I'd have to agree), which is to have a pristine high fidelity signal. Yeah, you have to crank it to get break-up, but that's kind of what rules about it.
I guess most people are going to be appalled by this. I would imagine the actual tube distortion from the amp wouldn't even be worth the installation of the MV pot, though. I mean, wouldn't a tube distortion pedal be a far better investment?
how dare you explain yourself and your position! i can't stand it when people who take the time to respond to a post actually have "something" to say and explain themselves.
anyway, this is partly why i'm asking, cause i don't know what a MV on one of these would sound like? i mean they put a MV on model T's and everyone seems to like them well enough. my sound city 120 has a factory installed master volume and it sounds good. and no i'm not saying a 1200 is a model T or a sound city 120. i didn't realize that i was the only guy out here that would like the idea of having a super loud amp that could do both clean and dirty sounds? i guess i should get a patent on the idea!
the other guitar player in my band uses a 50 watt head so cranking this thing isn't really an option. as for pedals, if i wanted to only use pedals i could've gotten a crate and saved a load of money. also if the amp can do what the pedal can do then why would you bother with the pedal?
I just can't see the amp itself breaking up all that much. It'd be more of a bluesy grit than anything, but maybe that's your aim? The older Sunn amps weren't designed with the same vision as the Model T. The T has the MV because it's designed to provide that sort of sound. The idea going into older Sunn amps was more along the lines of being able to offer hi-fi clarity at high levels of output(hence 100w Sunn amps with no master volume).
I hope someone with experience in doing this mod could offer some insight, but I'd say for the sake of your wallet and the amp, hold off until you can learn more.
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I to doubt it would break up all that much. I think a little natural breakup would/could be kind of cool...it's the kind of mod that I could test without having to make any permanent changes. With that said I did want to ask about it before I did it. Here is a link to what got me thinking about it, http://sunn.ampage.org/sdp/index.php/topic,1134.msg3111.html#msg3111
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xsolorusx has a point. The original intention of the older Sunn amps was to be clean at higher volumes. That's what was in when they were designed. Once you do the modification of having a MV installed you can't undo it, you've lowered the "classic value" of the amp....sort of like taking a 1964 1/2 Mustang and putting a sun roof in it.
My suggestion is - there are a lot of nice pedals out there that can duplicate the sound of tube distortion pretty well...from a slight bluesy overdrive to the cranking heavy distortion. Try one of those first before doing damage to a classic amp. I know that's not what you want to hear, but I believe it's good advice.
Rob
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why can't it be undone? all i would have to do is remove one of the 3 jacks i'm not using and install the pot, wire it up and i'm done and it would be just as easy to undo.
i don't think is realistic to compare my $610 Sunn to a '64 1/2 mustang...it's fine if you do, but i don't.
i understand what you guys are getting at, but if i can easily get real tube distortion from my amp or use a pedal, it's a no brainer...hell i build pedals and i still would rather have an amp do the work. what's the difference between using a pedal or giving it a MV? either way it's distorted and not being used as the "pristine super clean distortion repelling 1964 1/2 mustang" it was birthed to be.
and telling me to get a Marshall because i'm thinking about adding a MV to an amp that is half "Marshall" is kind or ironic or stupid, i'm never sure about those things...
i shouldn't be complaining though. i should have been more direct or focused with the heading and my initial post. i did ask for advice and that's what your giving. i just didn't realize how many originalists were here.
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The problem with removing one of the jacks and putting the master volume there is that the circuit should always go in as straight a line through the amp as possible, and the input jacks are on one end of the chassis towards the preamp. So if you added a master volume and put it there, then the sound would loop back on itself from the preamp, through all the circuitry as it moves down the chassis, and then back to the preamp area, and most likely would cause oscillation issues. The proper place to put it would be down further in the middle of the chassis past the tone controls. Unfortunately to do that would require you to drill a hole, or to move every one of the other controls over, leaving a space for a master volume knob. A better approach than the master volume is power scaling or VVR, but again, those would require holes to be drilled. If it is your amp and you don't care about any collectibility associated with it, then do what you want. If you do want to maintain resale however, then the least drilling of holes is adviseable. You could hook one up outside of the chassis on a temp basis and see if you like the effect. Be careful if you do this however so that you don't accidentally shock yourself when you go to turn the control. A typical master volume such as what Marshall traditionally used right before the phase inverter would work, though it would work much better if you put a 100k resistor in between the output of the master volume and the input of the phase inverter.
Greg
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thanks for the suggestions. i definitely won't be drilling any holes till i am 99% sure that the MV is worth it. just to be clear, your suggesting i try a putting a 100KR between the wiper of the MV and pin 8 of the PI?
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how dare you explain yourself and your position! i can't stand it when people who take the time to respond to a post actually have "something" to say and explain themselves.
Did you really need an explanation? I thought it was totally self-evident. A little on the harsh side, but I understood perfectly what they said and why they said it.
Having said that, I've often thought it would be nice to hear my Solarus in overdrive mode. But the Solarus (and from what I've read) most of the old classic Sunn tube amps take pedals extremely well.
Just a cheap-o Digitech Bad Monkey makes for an amazing variety of sounds. (Back in the day I played thru a Vox Tone Bender ) I can only imagine what a really, really good O.D. pedal would sound like.
I get what you're saying about the amp doing it so why bother with pedals, but it does seem a shame to modify a great classic Amp to turn it into something that it was never intended to be.
(Just my $ .02 )
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your right, i didn't need an explanation, but it would've been nice to have gotten one...
i do appreciate people urging others to not mod/screw up vintage gear as i often do it myself. i just don't think adding a MV is that big of a deal especially if it make the amp even more useful to the user.
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Wouldn't an attenuator be a better solution?
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Maybe, but I already happen to have the $2.00 worth of parts to do the mod where as I don't have the $200 or whatever it would cost to buy an attenuator. Also it would just be one more then to haul out on the road and have to not forget at the end of the night...
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thanks for the suggestions. i definitely won't be drilling any holes till i am 99% sure that the MV is worth it. just to be clear, your suggesting i try a putting a 100KR between the wiper of the MV and pin 8 of the PI?
Yes, the reason for it is that it isolates the pot from the grid of the phase inverter making sure there is no impedance change. This stops the thin sound at low volumes problem that Marshall JCM 800's were known for. The suggestion comes from Kevin O' Connor's series of books, which are expensive, but offer a lot of great info in them. If there is an input cap to the phase inverter already there, then the 100k resistor would go between the wiper of the pot and the cap. I don't remember offhand without looking at the schematic, and I don't feel like doing that for something so trivial.
If you're looking for more useful tones at lower volumes, then the power scaling that Kevin O' Connor sells is the best approach for that. The master volume won't drive the phase inverter much unless it is up past a certain level, and below that your tone will be clean. The power scaling allows you to get the tone you want, and then turn the volume and the power of the amp down. I'm going to be adding it to several of my amps soon.
Greg
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i'm gonna have a go at the MV tonight and i'll have to start looking in to power scaling...
the only thing in series between the wiper of the treble pot and pin 8 of the PI is a 100k resistor. the reverb and mid boost switch both get their signal from here after the 100k resistor.
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I would think that you should located the master volume then right before pin 8 of the phase inverter, with the 100k resistor you would add in between the wiper of the pot and pin 8. The other 100k resistor would be on the preamp side of the MV pot.
Greg
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I just tried it and for like 2 seconds I was getting some good fuzz then it dropped to a completely unusable volume. I double checked all my conections and even pulled the 100k between the pot and PI. I was still getting fuzz but at not much more than whisper. I don't have much in the way of spare parts so I didn't push it...
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Well it shard to figure out from your descriptions what was happening. It could be that it was oscillating....but again, hard to say.
Greg
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i decided just to get it all wrapped up and back together before i wreck it anymore than i already have. once i have a better handle on what i'm doing in there i'll have a go at it again. i'm at the point where i can't even enjoy it cause i'm just waiting for something to blow or pop...
thanks for your help. you definitely explained it in a way that was easy to understand which was very helpful.
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You're welcome and good luck with it. Keep visiting this forum as well as the others at Ampage, Webervst, Hoffman amps, AX84, etc and you'll keep learning. Lots of good books out there too if you really want to learn.
greg
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A few years ago when I was playing guitar in a band (I'm usually a bass player), I used my Sunn Sentura II amp. I used a distortion pedal, but I also used a Scholz Research Power Soak, and overdrove the input with my wireless. Each had a different sound. The non-pedal sounds were unpleasant unless I kicked in the midboost. With that on, the distortion was smooth and fat. Without it, it was harsh and thin, perfect for playing "Jumpin' Jack Flash"!
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If You want a REAL master volume Sunn....Get a Sunn Coliseum PA :
http://www.youtube.com/watch?v=Vf9WRHMB-DE&feature=PlayList&p=5C86F3CF0BD50C68&playnext_from=PL&playnext=1&index=4
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A few years ago when I was playing guitar in a band (I'm usually a bass player), I used my Sunn Sentura II amp. I used a distortion pedal, but I also used a Scholz Research Power Soak, and overdrove the input with my wireless. Each had a different sound. The non-pedal sounds were unpleasant unless I kicked in the midboost. With that on, the distortion was smooth and fat. Without it, it was harsh and thin, perfect for playing "Jumpin' Jack Flash"!
i haven't tried adding a MV since my initial attempt, but now that my amp guy has given it a clean bill of health i guess i should get back in there and mess it up. i find that mid boost removes a lot of low end and creates what i would call a more of a lead tone. distorted, it sounds pretty good. clean, it has a not so great breakup.