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diggum12
Silver Member
USA
282 Posts |
 Posted - 07/07/2006 : 15:27:36
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Greetings! I've been a longtime user of the site, but am a new member. Here's my Q: Is there a way to boost the output level of the DS-1?
I've read a lot of posts about maybe a bad batch floating around. That may/may not be the case w/ this. I did the Monte Allums Recto Mod on this a few months back, but that didn't affect the output level in any way. Any feedback is greatly appreciated! |
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stahlhart
Platinum Member
1318 Posts |
Posted - 07/07/2006 : 16:21:44
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It could probably be done -- operational amplifiers have huge potential in terms of voltage gain, depending on how they're set up in the circuit. There's probably one (more than likely, two) resistors whose values were determined for a certain gain level in the original design, so those could potentially be tweaked for more.
But I haven't messed with stuff like this in a long time, and I'd have to do some research to refresh my memory. I'm going to assume that this is the MIT circuit, by the way (though give or take circuit differences I think that you have pretty much the same situation with either MIJ or MIT).
One other thing to consider -- the clipping diodes are probably after the gain boost in these, so if those are still going to be in place then any gain you add before them is probably just going to end up being clipped to the same level. You'd almost have to add a gain stage after the clipping to get around that.
Might just be easier to add clean boost (i.e. MXR Micro Amp, Boss OD-3, PQ-4 etc.) after the DS-1 if you were certain that you didn't have a bad one. A DS-1 ought to be able to boost amplitude with or without clipping; at least my MIJ one does. I still need to figure out how it clips with the diodes removed; that's a rainy day project down the road when I've got a bit more time for electronic project work...
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stahlhart
Platinum Member
1318 Posts |
Posted - 07/07/2006 : 16:47:15
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Here's sort of what I'm getting at -- I'm not sure how accurate this schematic is for the DS-1; looks like someone took the main signal path and modified it by substituting a mechanical switch for the usual Boss FET switching... but assuming that the signal path drawing is accurate for the MIT DS-1, compare it to the non-inverting amplifier shown in the Wikipedia entry:
http://www.freeinfosociety.com/electronics/schemview.php?id=130
http://en.wikipedia.org/wiki/Operational_amplifier
Looks like the 1M resistor and the 500K pot wired as a rheostat are controlling the op amp's gain, and that perhaps increasing the value of the fixed resistor over 1M, the gain of the circuit could be boosted (G ~= 1 + R2/R1).
But also note that the two clipping diodes will probably render any voltage gain boost for the op amp moot as it stands now -- there would have to be gain afterward, as that 50K output level control is passive. The 50K control in the middle is for tone, and the rest of the circuitry on the (+) input of the op amp I'm guessing provides high input impedance and the correct signal level for that input.
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Edited by - stahlhart on 07/07/2006 16:49:33 |
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diggum12
Silver Member
USA
282 Posts |
Posted - 07/07/2006 : 17:13:05
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I was afraid of that. Monte's mod kit does replace those two clipping diodes D4 & D5 w/ 1n4002's.
I'm very anti-boost-pedal minded. I think clean boosts are great, but once I turn 'em on, I never turn em off which defeats the purpose of having another pedal there. I like lots of dynamics and prefer rolling my guitar back a little for rhythm and full out for solos. That's just me. :) |
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diggum12
Silver Member
USA
282 Posts |
Posted - 07/08/2006 : 07:43:46
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Well, I've got this one licked! I studied the schematic for a while and traced out the everything on the "level" path. I couldn't figure out for the life of me why R18 needed to be 1M. I guess it was needed to tame down the original diodes in D4 & D5. Well like I said, I did the Monte Allums mod which really smooths out the gain. The byproduct was great tone and gain, but a volume loss that was just a hair less than unity gain. That is not acceptable, of course.
I replaced R18 w/ a 10 ohm. That sounds really low, but it worked! I now have the level knob at about 8 oclock, so there's still room to spare.
It did slightly change the tone SETTING, but not the tone itself. The tone knob needs to be set lower now to get it where I want it, but it's still just as flexible. It's about 9:30 now instead of 10:30. Whoopdy-doo, it still sounds the same. I just have my level back now.
Hope this helps someone out there! |
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Boost DS-1 Output Level?
