Full transcript
0:00hey this is Joe gray bench Electronics
0:01welcome back to the pedal teardown
0:02Series where I take apart new and
0:04interesting pedals and show you what's
0:05going on inside today we have the
0:06classic Paul Cochran Timmy
0:10[Music]
0:12okay the Paul Cochran Timmy extremely
0:15popular pedal this would be classed as
0:17in a transparent overdrive pedal
0:19quote-unquote transparent the overdrives
0:21especially in the boutique worlds fall
0:23into two categories you either have the
0:25mid forward generally or some kind of
0:28like tonal coloring type overdrive pedal
0:31that has its own sound or you have
0:33transparent overdrives that
0:34theoretically don't meaningfully change
0:36the total characteristic of your guitar
0:38straight to your amp or through your
0:40other pedals it just adds Distortion the
0:42Timmy is more in the latter category
0:43where it's not supposed to be it's sort
0:45of its own sound like the sound of a
0:47Timmy it's more just supposed to add
0:48boost and gain and overdrive to your
0:51existing sound in practice it depends a
0:53lot on your guitar and your amps and the
0:55other pedals in your train whether or
0:56not that actually how is how it pans out
0:58but that's the idea these pedals are
1:01made by Paul Cochran he started building
1:03these I believe in 1997 and has built
1:06them consistently up until recently when
1:08I believe and correct me from wrong the
1:10Timmy here has been discontinued Paul
1:12does not make take the Timmy anymore you
1:14can still get it to me you just have to
1:16buy from mxr uh Paul Cochran and mxr did
1:19a deal now mxr sells a Timmy pedal out
1:22of their custom shop series I believe
1:24Paul also sells still a new version of
1:27the Tim which is the larger more
1:28features more controls version of the
1:30Timmy overdrive I think that's on
1:32version three now and I think he still
1:33makes and sells those it is a relatively
1:35simple overdrive pedal it is tube
1:37screamer-esque I don't want to imply
1:39that it's necessarily a two screamer
1:41copy because Paul himself has pushed
1:43back on that idea it's a it's an
1:45interesting thing when we say a pedal is
1:46a clone of another pedal it's it's not
1:49immediately clear by that statement
1:50whether or not the
1:52designer of the new pedal the Clone was
1:55looking at the original design and
1:57modified it and then put it out as their
1:59own or did modify it and put it out
2:01maybe a bit unscrupulously or we just
2:04look at the design of the new pedal and
2:06compare it to something older and say
2:07hey wow that looks a lot like that thing
2:09that's definitely the case for the Timmy
2:12that you don't have to squint that hard
2:14at the Timmy schematic to see the tube
2:16screamer but Paul says that he did not
2:19look at the two screen design in fact as
2:20far as I know Paul claims that he
2:22designed the Timmy pedal even before the
2:25tube screamer that's something I read
2:27that he wrote I'm not sure if he still
2:28stands by that I don't know when the two
2:29screener was designed exactly so not
2:31sure but the the circuit for the Timmy
2:34does look like a tomb screamer and you
2:37don't have to stand back that far that
2:39being said of course caveat number of
2:40parts in a Timmy are getting pretty
2:42close to the minimum number of Parts
2:44necessary to even have the Active
2:45Components work and do anything at all
2:48and not self-destruct so when you get
2:51down closer and closer to those building
2:52blocks it becomes harder harder to
2:55really call something a clone or a
2:57knockoff but we're going to look at the
2:59schematic in a second we'll have you
3:00know we'll look at that more as far as
3:02the actual pedal here we have a 1590b
3:04size enclosure the Timmy's came in a
3:07whole bunch of different finishes this
3:08one has a nice gloss red sparkle on top
3:11of a black powder coat the graphics are
3:13appear to be silk screened and sort of
3:15like an off-white color there are four
3:16controls bass gain volume and treble
3:19there's a switch in between the knobs
3:21here most likely a single pole double
3:22throw with a center off this is
3:24switching around the diodes in the first
3:26feedback loop of the first op amp stage
3:28five millimeter red LED indicator light
3:31standard filling latching three-pole
3:33double throw foot switch input and
3:35output Jacks Are side mounted 9 volt DC
3:38input jack is top mounted and it looks
3:41like the regular kobecon style pretty
3:43standard layout for uh older Boutique
3:45overdrive pedal that's pretty much it
3:47for the outside let's go ahead and crack
3:48it open and see what's inside
3:55all right so here is the inside of the
3:57Paul Cochran Timmy this is the version
3:59two if I hadn't mentioned that uh
4:00version one was done on stripboard or
4:02tag board these obviously have
4:04manufactured pcbs the circuit has also
4:06gone through a couple revisions
4:07depending on which version you're
4:09looking at this one the original
4:11versions had dip switches inside they
4:13control the clipping diodes the this
4:15version here has an external toggle
4:16switch the clipping diode Arrangement
4:18it's a little uh complicated but in the
4:20up position I believe this is the more
4:24compressed
4:25symmetrical clipping so what happens is
4:28there are strings of diodes here you
4:30have these four that are series diodes
4:32and then connected in the middle and
4:34we'll look at the schematic in a second
4:35and then this last diode here is
4:37connected also to the feedback loop
4:40however with a essentially a single Bowl
4:42single throw turning on and off so in
4:44this position the up is the more
4:46compressed setting so that's essentially
4:48knocking two of the four clipping diodes
4:51out so you just have the symmetrical
4:53back to back of a single diode across
4:55the feedback loop in the middle position
4:58the the bridge between the diodes is not
5:00connected to the other side of the loop
5:02and so you have the strings of diodes to
5:05this way and two this way so that's
5:06going to give you a higher forward
5:07voltage effective forward voltage which
5:09means less compressed so the middle
5:11position is going to give you the least
5:12amount of clipping the most amount I had
5:13room but it's going to be symmetrical
5:15clipping when you have clipping at
5:16higher gain levels and then the down
5:18position is the asymmetrical so that
5:20brings in this extra diode across a
5:22feedback loop but there's no matching
5:23symmetrical ones so you still have the
5:25two and the two from this Bank of diodes
5:27but you also have just this one across
5:29it which is going to give you that
5:30asymmetrical clipping as far as the
5:32build here we have the switchcraft style
5:35112bx non-isolated or insulated quarter
5:39inch Jacks that's most likely how or not
5:41most likely definitely how the pedal is
5:43getting grounds in the enclosure we have
5:44a three-pole double throw latching foot
5:46switch interesting is the same color as
5:49the ones that I like think of as the
5:50gorva foot switches these things right
5:52here but you can tell the epoxy design
5:54is a little bit different so it's not
5:55quite the same I'm not sure who made
5:57these foot switches as well as far as
5:59actuation pressure
6:00it's not as bad as the blue Cheapo three
6:03pull double throws but it's not as nice
6:05as these either so somewhere in the
6:06middle there is room in here for a nine
6:08volt battery and quite cleverly I should
6:11say Paul Cochrane uses the ground tab
6:14for the output Jack or excuse me input
6:16jack
6:16as a little string relief tie off point
6:19with a zip tie here on the battery cable
6:21which I think is a great idea so often I
6:24see these battery cables just sort of
6:25flopping around inside pedals which
6:26always makes me nervous because if you
6:27pull on this and there's no strain
6:29relief you're just pulling on the solder
6:31joints up here well one's going to be
6:32connected to the input jack on the ring
6:34terminal if it's a negative ground pedal
6:37the red Power is running up here to the
6:39input jack and if you pull on that
6:41you're just pulling on the solder Jack
6:42solder joints but this has string relief
6:44here with the zip tie which is a good
6:45idea and you don't have to use the
6:46Ground Terminal for the input jack as
6:49long as the Ground Terminal for the
6:51Apple Jack is being used and connected
6:52the circuit ground you still have ground
6:54so you don't have to use that for the
6:55circuit you can use it as this
6:57connection or tie off point as far as
6:59components we have carbon foam resistors
7:01excluding at least that metal film blue
7:04resistor right there box film capacitors
7:06with the exception of the uh the little
7:08film polystyrene plasticky piece right
7:12there that is the hunter picofarad cap
7:15across the feedback loop we also have a
7:17couple electrolytics up here these are
7:19most likely power filtering you're going
7:21to have one across the rails for the
7:23nine volt power and then one probably
7:25filtering the biasupply for the op amp
7:27this pedal does have sort of an offset
7:29biasupply so that's created with these
7:31two resistors here the 8.2 K and the 10K
7:34so that's not going to create a perfect
7:36half Supply voltage because it's just a
7:39voltage divider if you want to perfectly
7:40half it beats to the same value but 8.2
7:42K and 10K is going to be selected
7:44specifically according to Paul to
7:46maximize the Headroom out of the op amp
7:47op amps unless you get a rail to rail
7:50op-amp it's not going to operate
7:51perfectly rail to rail and so that
7:52combination of resistors is
7:56specifically selected to get you maximum
7:58Headroom holy score Nepal speaking of
8:00the op amp the op-amp selected here is
8:02the 4559 jrc 4559 the DC jack is indeed
8:06a kobecon or at least kobecon Style with
8:08the internal plastic nut PCB we can see
8:11pretty clearly there's a nice big ground
8:13plane most likely ground poured on the
8:15the top side a PCB by the way I decided
8:18not to take it out of the enclosure here
8:20because number one we all know Timmy is
8:23a known circuit it's not there's no need
8:25to trace it and also it's a valuable
8:27pedal and not having to desolder the DC
8:29jack does maintain a bit of that
8:31Integrity of the pedal or whatever so
8:33we're keeping it in here it's a Timmy we
8:35know it we love it it's all good so this
8:37is the drawing of schematic by
8:39goobbuster from
8:40freestoneboxes.org it was redrawn
8:43apparently in 07. which was uh oh my God
8:4716 years ago and credit to Paul they did
8:50come and comment on that thread and made
8:52some adjustments and clarifications
8:53kudos for that the clipping setup here
8:57this is the V1 clipping setup so it does
9:00it's not quite like this anymore this
9:01diode is gone now
9:03there is no dip switch and instead it's
9:06just a single essentially a single pole
9:08double throw like this
9:12and this is going to come and either
9:15connect there or not so that's the down
9:17position in the down position on the dip
9:21switch this is closed and that's giving
9:23your asymmetrical clipping and then the
9:26other switch is essentially coming here
9:28like this
9:30connecting the bridge over to one side
9:34of the feedback loop so when this is
9:36closed which is like the dip switch
9:37being up these two diodes are
9:40essentially out of well they're they're
9:41shorted so they're you're just getting
9:44this side of the feedback loop connected
9:46to these two diodes so it's going to be
9:48more compressed because you don't have
9:50the series diodes and they're higher
9:52forward voltage or effective for a
9:53voltage but it's still symmetrical you
9:55still have one going one way and one
9:56going the other and then when it's the
9:58asymmetrical position this is still not
10:00being connected the bridge here is not
10:02being connected to this side of the
10:03feedback loop but you're bringing in
10:04this diode which gives you the
10:06asymmetrical clipping other than that at
10:08the far as the circuit you can see
10:09pretty clearly where people would want
10:12to call this a tube screen with
10:13derivative you have a dual op amp diode
10:16clipping in the first b-back Loop and
10:17then a second gain stage the two
10:19screamer has its tone control integrated
10:21into this op-amp stage where this has a
10:23treble cut
10:24in between the base cut here is
10:26essentially the same idea as seeing like
10:29a base control cut on the input of uh we
10:32looked at one panel oh the the zap
10:34machine has the the base control what
10:36the potential between and where you're
10:37blending between two caps that's
10:39essentially the same thing as What's
10:40Happening Here uh except it's just
10:42coming off the feedback loop but you're
10:43blending between the one microfarad cap
10:45and the 39 nanofarad cap down here our
10:47power supply is pretty standard polarity
10:49protection not not the preferred way
10:51anymore we don't do this anymore because
10:52if you connect negative polarity I
10:54shouldn't say we don't do this a lot of
10:55people do but I don't think it's the
10:57preferred way because we have really low
10:59forward voltage shock these now when you
11:01do it this way and you connect negative
11:03polarity theoretically this diode is
11:04just going to burn out and then if that
11:06opens up then the circuit will just
11:08operate negatively until something else
11:09breaks now we just do instead of this we
11:13do a uh one of like a 58 17 in series
11:17that if you put if you try and put
11:19negative voltage here the cathode of
11:22that diode is just going to block it 47
11:24microfarad filter resistor that's one of
11:25the electrolytics and here's that
11:27voltage divider that's offset the 8.2 K
11:30versus the 10 10K which is going to put
11:32out something not quite you know if this
11:35was 10K and 10K you would expect
11:37approximately 4.5 volts here for the 9
11:40volt input but because we have two
11:42resistors that aren't the same value
11:43this voltage is not going to be quite
11:45that much it's going to drop a little
11:47more voltage across the 10K so this is
11:48going to be a little higher it's going
11:50to be you know 5 volts or whatever and
11:52then after that trouble control out to
11:54another using up the other side of that
11:56op amp and then a 10K volume output to
12:00the output switch the alpha Jack so that
12:02is the Timmy a very famous well-known
12:05overdrive transparent overdrive quote
12:07unquote from Paul Cochrane not available
12:09anymore as far as I know directly from
12:11Paul but you can still get the mxr
12:13version and if you want to go for the
12:14bigger 10 version I think Paul still
12:16sells those so let's go ahead and put it
12:18back together
12:33all right that is a wrap on the tarot
12:35for the Paul Cochran Timmy if you have
12:37any questions or recommendations for
12:38pedal you want to see on a future tear
12:40down episode let me know in the comments
12:41if you enjoyed the video I'd appreciate
12:43you hitting the like button and
12:44subscribing I'm Joe from greybench
12:45Electronics thanks for watching
12:48foreign