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MoonWatcher
Bronze Member
USA
98 Posts |
 Posted - 06/04/2009 : 19:07:07
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quote:
Originally posted by gmreszelMoon, you mention just some minor resistor changes and such for BD-2. Is there a post or schemo or theory post that helps me explore these simple changes? I think that's what I'm after is subtle refining for the bd.
There should be a schemo in the appropriate sticky thread above.
You can analyze the circuit - I'll give some ideas on resistors to change, and why.
R31 is your first gain stage resistor that helps determine how hard it runs. The stock value is 1.5K - pretty low, so it runs pretty hard. IMO, this should be increased for less drive. But if you tweak it, you have to adjust C22 to keep the HP filtering the same.
R32 (2.2K) is the 1st gain stage's slew rate limiter. Some folks will increase C21 (external compensation cap), but adjusting R32 higher slightly can yield smoother drive characteristics IMO.
The next set of resistors are in a "simulated" fixed Fender tone stack:
R37 - blocks treble, analogous to treble on zero (330K)
R38 - "slope" resistor, determines "separation" or overlap between treble and bass/mid controls (100K, scooped BF Fender tones)
R50 - boosts bass, analogous to bass on 10(+!!!) (1M)
R51 - determines how much midrange is bypassed around tone stack (15K)
...The above tone stack passes too much bass IMO. And even with R51 at 15K (some Fenders used 6.8K), you still get the classic BF Fender sucked mids thing. Reducing R38 and R50 and increasing R51 seems to make things much more friendly.
R35 sets the input impedance of the 2nd gain stage, stock value of 1M. This slams Q14 with a ton of signal. Reduce it to soften things.
R34 (2.2K) determines how hard the 2nd gain stage is driven. Depending on how you adjusted the gain of the first stage, you may need to alter R34, And C24 is it's companion in the HP filtering of this stage.
R25 (2.2K) is your second stage slew rate limiter, which can be finessed if adjusted slightly.
R26 helps to bleed off some highs after the two gain stages. It's also an opportunity to attenuate the overall signal before it goes on to the post-level op amp. But you have to be careful here, because it will effect the tone circuit, and C19 will most likely need to be adjusted as well.
The op amp has a gyrator (simulated LCR) which is mainly boosting pretty low frequencies. While many folks are content playing with the caps in the gyrator (C8, C9, C16), the resistors play a big part as well, particularly with the Q of the gyrator. The three to play with are R9, R10, and R21. This post is getting long, so I'll leave the gyrator research up to you.
So that's about a dozen resistors that you can tweak, that only require adjusting a few caps along with them, and can be done before you start playing with other caps, the clipping diodes, or the op amp that most modders are so eager to start hacking out. |
Edited by - MoonWatcher on 06/04/2009 20:11:52 |
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 06/04/2009 : 19:18:40
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quote:
Originally posted by archimedes I think that that biggest problem with all mods is that you are usually taking a shot in the dark. It's all down to your ears (and fingers) and all the samples and reviews on the net will not ultimately help that much at the end of the day. Best thing IMHO is to get to a good store (or stores) with a wide selection of the type of box you are after on a quiet day and try them all out until you find the right one. That way you can hear for yourself.
Some of the newer breed of modders are pretty eager to tweak their designs for your purposes if you contact them. Especially if you're dealing with someone who's working on a small scale, and doesn't have a ton of premodded pedals or prepackaged baggies rolling off some sort of "assembly line." While they may not get it 100%, you might be pleasantly surprised at how much closer to your needs it will be versus going to a store and trying out a bunch of pedals and still having that be a bit of a shot in the dark, as well. |
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bassinyourface
Bronze Member
France
76 Posts |
Posted - 06/04/2009 : 22:06:38
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 WOW Moon watcher
you have a deep understanding of the bd circuit !
No joke here,i'm really VERY impressed ! |
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gmreszel
Copper Member
USA
32 Posts |
Posted - 06/05/2009 : 00:18:44
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quote:
Originally posted by bassinyourface
WOW Moon watcher
you have a deep understanding of the bd circuit !
No joke here,i'm really VERY impressed !
I concur and could not have said it better - thank you very much! |
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zerksies
Double Platinum Member
USA
3406 Posts |
Posted - 06/05/2009 : 00:49:25
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| I have the keeley ds-1,bd-2,tr-2 and love them. i also have the monte allums cs-3 opto plus mod and it is great as well, way better over the stock pedals |
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cctsim
Silver Member
United Kingdom
418 Posts |
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Ward
Copper Member
Australia
28 Posts |
Posted - 06/05/2009 : 02:31:57
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Hey guys, I'm new here but I'd like to contribute to this thread if I may, to all you pedal dudes, I don't mean to step on anyone, I have a collection of pedals myself BUT:
I think a lot of people ask pedals to do too much, ie, to run an SD-1 into a clean amp an expect a great tone is putting the cart before the horse IMHO. It's far better to find the amp that will give you the core basis of what tone you're into, then, find the speakers that take you further along the tone quest and then, put a pedal in front of it all to just give you some extra hair or in other words, use the pedal as salt n pepper and not the meat in the sandwich.
Of course, it's extreemly costly to experiment with amps and speakers and this is the reason most people spend so much time and money on pedals. It's a roundabout, I did it myself for twenty odd years, pedals pedals and more pedals, money money and more money.
Then one day I sold both of my Marshall amps, this gave me enough money to start buying and building Marshall clone amp kits, from there I have built amps, sold amps, built more amps, learnt how to mod them so they deliver closer to what I'm looking for etc etc.
My exp so far is that I am yet to find the perfect amp, but, I am so much closer than just buying corporation production line Chinese made amps. I realise that most dudes will never be able to build and mod their own amps, what I'm saying is: pedals will never get you there on their own, you have to have the right amp and the right speakers, not to mention the guitar and pickups but anyway, that's another story.
I do have a little exp with modded/ing pedals though which may or may not be useful?
The BD-2, well there are better pedals out there, I tried Keeley's modded BD-2, sold it. Never heard it stock but read a lot of negative stuff about it.
The SD-1, I tried all of Monte's mods with this pedal, in the end, I just gave up and moved on.
The MT-2, I don't know what I was looking for with this thing but after I put Montes mods into it, I thought it was better stock and a lot of people say the same, I sold it fast.
The TS-9, to me, this is the most over rated pedal out there, stock or modded. I sold it. I can't believe how many incarnations of this circuit there are out there and how basically the same they all sound but how costly a lot of them are because someone has built one using metal film resistors, film caps, the obligatory bright LED and the also obligatory true bypass.
The fact that SRV used the 808 doesn't mean it'll sound any good at all in front of a clean amp running on vol 3, SRV used it by having the gain on zilch and the output up so it was just adding a hair to a Fender amp on ten, you have to have the amp going hard first, this brings us to the ever present fact that the amp is now too loud, bummer, there are thing you can do (another story)to lower the vol but the amp has to be running hard to sound like the big boys, that's just life.
I've done quite a few Monte mods, the OD-3 was another disaster, most of them saddened me big time. One thing I did learn was that his so called "hifi mods" ( which most if not all modders do)where they replace stock caps for "better" quality caps of the same value always made the pedals sound clinical and lifeless, they were that stock but were made worse by the "hifi mods"
I'd 99% given up on Monte's mods until I tried his CS-3 mods, the H2O mods I think they're called. I did the mods and again I thought the pedal lost something, so I removed all the "hifi" caps and put the stock ones back in and found that I really liked the pedal now, that was 2 years ago and I still have that pedal now so that says something.
Recently I wanted to try a GE-7 and seeing as Montes GE-7 mods include swapping out 5 chips I decided to give it a go, I like this pedal very much as well.
Both the CS-3 and the GE-7 are used in my setup as salt n pepper and because I don't ask a lot of them, they contribute wonderfully. I have the NS-2 in there as well just for protection seeing as I'm basically a strat dude most of the time and well, we all know how strats are the nasty noise guys in town. I've tried all manner of Boooteeeek pocket emptiers and found them to be a waste of money.
General Guitar Gadgets do a lot of clone kits which are excellent and cheap, I have the Blues Breaker and love it for some SRV type stuff for lack of a better description, this pedal is the quietest booster I've heard, after the success of the BB I decided recently to buy the GGG reverb pedal kit and am very pleased with it as well. I've tried at least 6 verb pedals over the years and they all sucked for one reason or another but the GGG D Verb as it's called is quiet and the verb doesn't get louder when you hit a booster (ala the Boss RV-3 which I liked for it's verb but you hit a booster and the verb just takes off) it has one knob and that's all you need, it is cheap and the actual verb is usable, not great but at least I don't  when I hear it.
I hope I haven't offended anyone here by dissing any particular pedal etc, I'm just saying, get the best amp and speakers for your sound, then add the pedals as salt n pepper so you're not asking the pedal to be THE tone and your pedals will sound a lot better. The amount of money I've spent over the years chasing my tail with pedals could have paid for at least 5 amps I reckon |
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 06/05/2009 : 14:05:07
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quote:
Originally posted by Ward
It's far better to find the amp that will give you the core basis of what tone you're into, then, find the speakers that take you further along the tone quest and then, put a pedal in front of it all to just give you some extra hair or in other words, use the pedal as salt n pepper and not the meat in the sandwich.
Of course, it's extreemly costly to experiment with amps and speakers and this is the reason most people spend so much time and money on pedals.
I hope I haven't offended anyone here by dissing any particular pedal etc, I'm just saying, get the best amp and speakers for your sound, then add the pedals as salt n pepper so you're not asking the pedal to be THE tone and your pedals will sound a lot better.[/br]
I think you really hit the nail on the head regarding a great many things - thanks for such wonderful elaboration.
Good pedal tones always start with good gear before and after them. Not only is the amp important, but pickups can play a huge role as well. I find that many higher output pickups really trash the sound of things down the line.
The amp thing can be a grail search in itself. I've owned possibly 50 amps, have built over a dozen in the past 5 years or so, and currently own about 7. I've also demoed about 2000USD worth of 12" speakers alone, and I'm not done yet. Another caveat with the "grail amp" thing is power - low watt amps sound good at lower volumes for the most point, and the bigger boys are almost necessary for fuzz pedals or anything with a lot of low end.
...I've also gone to quite a few head and cab setups, since different pedals shine with speakers that break up either later or sooner.
I also might (wrongly) assume that if we're talking about great amps that you mean valves/tubes, which are expensive and require periodic maintenance. And quite a few current production tubes are garbage, IMO.
There are amps that are very pedal friendly and others that are not. IMO, Fender amps made from about the 60's forward and anything with a similar styling generally are very flexible with pedals, especially the 30-40 watt models, such as the Vibrolux, Pro, and Super. The Deluxe Reverb can be a little dodgy because it doesn't have the necessary power IMO, and it will sound terribly bright unless you put a speaker in it with a smooth top end.
You mentioned Marshall amps. Aside from some fuzzes, treble boosters, and a few other pedals that seem to work well with the typical midrange heavy and easily dirtied Marshall tones that you probably won't get far with a great many pedals. The reason why SRV got good tones with a TS into a Marshall was because it was a 200 watt Major!
...The little 18 watter 1987X and other similar pint sized Marshalls that are so popular of late are kind of twitchy with pedals as well, IMO. Small cathode bypass caps, no choke, and cathode biased EL84's that can do the "cold bias shift" thing when slammed with a big chunk of signal.
But back to modded stuff - I agree with most of your sentiments regarding them. I really don't care for many mods that include tantalums or op amps that were designed for high end audio. You need some noise in the line IMO that the signal then modulates (or is modulated by) to get some of the best tones). Metal film caps aren't so horrible, and have the advantage of fitting nicely in a Boss pedal.
But I will repeat it - many modders seem to miss the boat when it comes to changing resistors. You can steer at least 70% of the tones of a pedal to a better place, IMO just by tweaking resistors. Cap changes come somewhere after them, and semiconductor swaps should be a last resort thing, IMO. |
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Shermock
Bronze Member
Sweden
61 Posts |
Posted - 06/05/2009 : 14:41:32
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Nice discussion!! this aint the usual "run of the mill" talk
What is the "cold bias shift"?, never heard of that.
Totally agree on the subject since no pedal sound good without a nice guitar and amp. Though i love pedals i would feel totally safe and confident going to gig with only my guitar and amp.
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gmreszel
Copper Member
USA
32 Posts |
Posted - 06/05/2009 : 16:35:22
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Another's knowledge is definitely a treasure, thanks loads everyone.
I'm a purist and over the years I would find myself vascillating from using many toys to make the noise ie, more colors on the palette to finding a great amp and just plugging in a cord. I remember after years of twiddling with so many setups I had told myself that I would just go to the gig with amp and cord. When I finally did, it was absolutely liberating in the way it made me think about my sounds and how to get them. Also liberating that now I can do a gig with any amp situation (oops I forgot the supply to my pedal board) as long as I can get a dirt - everything else you must acquire from guitar vol/tone and pickup selection.
My return to toys is for simplicity for the small gigs where I can take a little 4x10 bandmaster stack (instead of the 2203 and 4x12) and get the necessary tones from the boxes. I want to leave the practice of buying, trying and/or building amps behind, get a few simple boxes that I can tweak (or not if I don't have to) and leave the boutique discussions and purchase dollars to those that want to continue that path. Building amps is awesome if you have that ability and really its very accessible to people now with all the kits, 5E3, 18watts and the like out there. It is just an area I don't want to pursue. I happen to be fortunate that I build my own guitars because I can see through all the boutweek guitar hogwash and I'm sure it infects all areas of this instrument we love.
Mark it that I'm a professional gigging musician who needs real working tones for the stage, all pragmatic - the best tools to pay the bills and put my son through school. I say this in no way condescendingly (that means talk down to by the way  ) but it's so much different live than studio or the home hobbyist so input from you giggers is important to me. |
Edited by - gmreszel on 06/05/2009 16:45:24 |
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 06/05/2009 : 17:02:36
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quote:
Originally posted by Shermock
What is the "cold bias shift"?, never heard of that.
My nomenclature is probably poor, as I'm attempting to grasp for some sort of "layman's" term. But basically speaking, with a cathode biased power section, there's always the possibility of distortion when hit with a big signal (power chord, low fretted notes, neck pickups, etc.) that will make the amp temporarily behave as if it were a fixed biased circuit adjusted for too low (cold) of a bias.
The only "reservoir" that a cathode biased setup has (in traditional designs) is the cathode bypass capacitor. In an amp like a tweed Deluxe, it's notoriously small - 25uF. It gets bigger in Voxes (~200uF) and the Marshall 1987X (~500uF), and for some mods I've seen Epi Valve Juniors with it pushed all the way up to 1000uF, but it's still limited.
The cathode biased setup can work quite well if you use solid state rectification and big filter caps on the mains, which bolster the bass and power reservoir nicely. But with a tube/valve rectifier, the filtering has to be lighter to keep from killing it (the rectifier). And you're also dealing with power supply sag in class AB (push pull) circuits as well.
While cathode bias, low B+, and tube/valve rectification can create really great distortion and overdrive without pedals, in many instances it can be hard to dial in good tones with them.
So fairly off topic (and I apologize), but coming full circle back to the application of pedals makes it relevant. |
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MoonWatcher
Bronze Member
USA
98 Posts |
Posted - 06/05/2009 : 17:24:03
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quote:
Originally posted by gmreszel
My return to toys is for simplicity for the small gigs where I can take a little 4x10 bandmaster stack (instead of the 2203 and 4x12) and get the necessary tones from the boxes. I want to leave the practice of buying, trying and/or building amps behind, get a few simple boxes that I can tweak (or not if I don't have to) and leave the boutique discussions and purchase dollars to those that want to continue that path.
Mark it that I'm a professional gigging musician who needs real working tones for the stage, all pragmatic - the best tools to pay the bills and put my son through school.
I own a 2204 with a 2X12 cab, and I'm constantly harassed by gigging guitarists for lower volume dirt tones. These are the big two regarding why I've returned to pedals as the practical answer. Even a cranked Deluxe Reverb or 1987X will get you in trouble in many clubs!
...For the above reasons, I've found a lot of solutions with tweaked SD-1's for mild overdrive, tweaked DS-1's for the next step up, and tweaked BD-2's for stuff in between. For something great stock out of the box IMO, it has to be the OD-3.
The MT-2 is a tough one, because there's just so much cascaded gain. I really don't like it stock out of the box, and tweaking it is pretty much a subjective thing. |
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Shermock
Bronze Member
Sweden
61 Posts |
Posted - 06/05/2009 : 19:03:06
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Thanks Moonwatcher for the info.
the sag you get from tube rectifiers is really cool.
ive been curious about what differences "cold" vs "warm" bias would do to the tone. gonna sit in next time I change my tubes and investigate further
About pedal mods Ive only done one, did a TS-9 to TS-808 specs (changed the chip and two resistors, very skilled technichan i am ). The mod did open up the pedal a bit and i liked it much better than a stock TS-9. |
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gmreszel
Copper Member
USA
32 Posts |
Posted - 06/06/2009 : 17:24:07
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quote:
Originally posted by MoonWatcher
quote:
Originally posted by gmreszel
My return to toys is for simplicity for the small gigs where I can take a little 4x10 bandmaster stack (instead of the 2203 and 4x12) and get the necessary tones from the boxes. I want to leave the practice of buying, trying and/or building amps behind, get a few simple boxes that I can tweak (or not if I don't have to) and leave the boutique discussions and purchase dollars to those that want to continue that path.
Mark it that I'm a professional gigging musician who needs real working tones for the stage, all pragmatic - the best tools to pay the bills and put my son through school.
I own a 2204 with a 2X12 cab, and I'm constantly harassed by gigging guitarists for lower volume dirt tones. These are the big two regarding why I've returned to pedals as the practical answer. Even a cranked Deluxe Reverb or 1987X will get you in trouble in many clubs!
...For the above reasons, I've found a lot of solutions with tweaked SD-1's for mild overdrive, tweaked DS-1's for the next step up, and tweaked BD-2's for stuff in between. For something great stock out of the box IMO, it has to be the OD-3.
The MT-2 is a tough one, because there's just so much cascaded gain. I really don't like it stock out of the box, and tweaking it is pretty much a subjective thing.
Thank you for this post, that's exactly what I'm talking about and looking for. |
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gmreszel
Copper Member
USA
32 Posts |
Posted - 06/06/2009 : 17:32:36
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quote:
The thing with the real Marshalls, sorry to the 18 watt dudes that would be JTM-45 upwards to the 2203 or plexi (I'll leave out the DSL and TSL if I may)is that yes they will deliver the dirt but there is plenty of clean headroom esp with the 100 watters, it's not Fender clean but it's clean n useful.
I guess it depends on the gig. Like moon mentioned above the Deluxe will get you in trouble in a club and I agree. My 2061 was as close as I ever got to the perfect amp. The one where you do the whole gig with it and a wah/chorus/OD/Delay and that's it - you can get all the sounds you need for any cover. But for the small clubs here a dimed 18 is way too loud. I was contemplating getting an Ultimate Attenuator but it never happened and I ended up selling the amp.
Anyway, thanks again everyone for your input, I think I have some great answers and I'll go back to my guitar cave and contemplate the mods. Cheers you all lots,
GM Reszel |
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Opinions on mods, keeley, allums, et al
