Paul Cochrane - Tim pedal

mensur · Post by **mensur** » 06 Jun 2011, 17:36

Is it like this?

Post by **bubstance** » 04 Sep 2011, 01:48

Just a bump to show the way that the Tim's boost controls are wired in.

The abruptly ending leads go to the feedback loop, VB is +4.5v.

Post by **bubstance** » 05 Sep 2011, 20:37

And at the request of another member, here's the full schematic. In the last mini schem I seem to have switched the Bass Cut lugs around, so that's fixed.

Use your favorite power scheme and you've got yourself a Tim.

paulc · Post by **paulc** » 05 Sep 2011, 22:36

The clippers are wired a little different now due to the 3-way toggle, and there's an additional cap across the loop of the output amp (4n7). The treble control is not exactly like I do it. The 1k5 is wired in like the 3k3 on the gain pot.

Post by **bubstance** » 05 Sep 2011, 22:41

**EDIT** Nevermind.

Updated except for the clipping.

paulc · Post by **paulc** » 05 Sep 2011, 23:54

bubstance wrote:**EDIT** Nevermind.

Updated except for the clipping.

The treble pot really doesn't make a difference either way. I just got in the habit of doing things like that when I used perf. It would have worked the same way before you updated it. The 4n7 limits the high freq responce of the output amp. There was no reason for it to be flat 20khz and beyond even when used as a flat booster. Right now it's about -3dB @ 7khz when the treble control is on zero. This is just above the point where I could start to hear a loss with the brightest clean guitar rig.

The toggle is just a spdt on/off/on. One leg goes to the junction of the 4 diodes shorting out two of them. The other leg brings in a single diode which then parallels the 4 for a 2/1 setup.

bajaman · Post by **bajaman** » 06 Sep 2011, 00:29

just saw one of these on my workbench - I had to replace a faulty bypass footswitch (not your fault Paul C

).
I must admit that I was quite pleasantly surprised at how nice it sounded when i gave it a test run afterwards.
Definitely NOT a Klon OR a high gain squashed distortion pedal BUT perfect for bluesy stuff and a great boost feature that really works.
Loved the bass and treble controls - a well thought out design.
The model i had did not have any dip or toggle switches - and in my opinion it does not need them.

If you own a nice tube amplifier this pedal is well worth trying as a gain booster and is VERY reasonably priced and well constructed internally.
Top marks Paul

bajaman

paulc · Post by **paulc** » 06 Sep 2011, 00:56

bajaman wrote:just saw one of these on my workbench - I had to replace a faulty bypass footswitch (not your fault Paul C ).
I must admit that I was quite pleasantly surprised at how nice it sounded when i gave it a test run afterwards.
Definitely NOT a Klon OR a high gain squashed distortion pedal BUT perfect for bluesy stuff and a great boost feature that really works.
Loved the bass and treble controls - a well thought out design.
The model i had did not have any dip or toggle switches - and in my opinion it does not need them.
If you own a nice tube amplifier this pedal is well worth trying as a gain booster and is VERY reasonably priced and well constructed internally.
Top marks Paul
bajaman

Thanks for that! I think you had an older one with the pull pot for the boost control. That gave two clipper settings to play with. If so I'm sorry about the pain it was to change that footswitch! When I changed to the toggle design I took the footswitches off the board to make it a 10 minute job to replace them. Now the pedals have the pots/toggle on the board.

thanks again, Paul

Post by **bubstance** » 06 Sep 2011, 01:15

Thanks for all the information, Paul. Just a quick question or two...

So now the Tim's have 5 diodes instead of 6? So if I understand this correctly, on the newest models the clipping switch functions with 2 diodes in the up position, 4 in the center, and 5 in the down position? Very clever setup, by the way. I loved the sound of my Tim back when I had it... I've just been lazy and hadn't drawn out a schematic until yesterday.

DrNomis · Post by **DrNomis** » 06 Sep 2011, 02:13

The toggle switch wiring has been puzzling me for some time, come to think of it....

DrNomis · Post by **DrNomis** » 06 Sep 2011, 02:22

askwho69 wrote:Thanks PaulC you're genius EAR and Idea... By the way can i ask what does the second Opamp do? like the pin 6 and 7?sorry im learning so need to ask

I just had a look at the schematic, the second op-amp has a gain of 1 (see where the two 3k3 resistors are?), the 3k3 resistor between pins 6 and 7 feeds the output of the op-amp into it's - input....

earthtonesaudio · Post by **earthtonesaudio** » 06 Sep 2011, 02:56

DrNomis wrote:
askwho69 wrote:Thanks PaulC you're genius EAR and Idea... By the way can i ask what does the second Opamp do? like the pin 6 and 7?sorry im learning so need to ask

I just had a look at the schematic, the second op-amp has a gain of 1 (see where the two 3k3 resistors are?), the 3k3 resistor between pins 6 and 7 feeds the output of the op-amp into it's - input....

Second op-amp gain is TWO, not one.

The gain formula for a non-inverting op-amp is (1+Rf/Ri) where Rf=3.3k and Ri=3.3k.

paulc · Post by **paulc** » 06 Sep 2011, 03:07

DrNomis wrote:
askwho69 wrote:Thanks PaulC you're genius EAR and Idea... By the way can i ask what does the second Opamp do? like the pin 6 and 7?sorry im learning so need to ask

I just had a look at the schematic, the second op-amp has a gain of 1 (see where the two 3k3 resistors are?), the 3k3 resistor between pins 6 and 7 feeds the output of the op-amp into it's - input....

Actually it's a gain of 2, or 6dB. Noninverting opamps add 1 to the gain formula. The new cap puts a 6dB hi cut shelf in there. I've been thinking of bumping up the values of the 3k3 resistors so there's less loading on that stage to try and get a little more headroom out of it though.

The diodes go 4 in the middle position, 3 (2/1) in the up, and 2 in the bottom. 5 diodes total. I've been thinking of changing this also to kick in a cap to the bass control to add some more mids when using the more saturated settings.

Thanks for the comment askwho, but to be honest this is pretty basic stuff. Most of what you see in analog dirt boxes when it comes to the circuit is covered by 3rd semester electronics.

paulc · Post by **paulc** » 06 Sep 2011, 03:09

earthtonesaudio wrote:
DrNomis wrote:
askwho69 wrote:Thanks PaulC you're genius EAR and Idea... By the way can i ask what does the second Opamp do? like the pin 6 and 7?sorry im learning so need to ask

I just had a look at the schematic, the second op-amp has a gain of 1 (see where the two 3k3 resistors are?), the 3k3 resistor between pins 6 and 7 feeds the output of the op-amp into it's - input....

Second op-amp gain is TWO, not one.

The gain formula for a non-inverting op-amp is (1+Rf/Ri) where Rf=3.3k and Ri=3.3k.

beat me to it!

DrNomis · Post by **DrNomis** » 06 Sep 2011, 03:12

paulc wrote:
DrNomis wrote:
askwho69 wrote:Thanks PaulC you're genius EAR and Idea... By the way can i ask what does the second Opamp do? like the pin 6 and 7?sorry im learning so need to ask

I just had a look at the schematic, the second op-amp has a gain of 1 (see where the two 3k3 resistors are?), the 3k3 resistor between pins 6 and 7 feeds the output of the op-amp into it's - input....
Actually it's a gain of 2, or 6dB. Noninverting opamps add 1 to the gain formula. The new cap puts a 6dB hi cut shelf in there. I've been thinking of bumping up the values of the 3k3 resistors so there's less loading on that stage to try and get a little more headroom out of it though.

The diodes go 4 in the middle position, 3 (2/1) in the up, and 2 in the bottom. 5 diodes total. I've been thinking of changing this also to kick in a cap to the bass control to add some more mids when using the more saturated settings.

Thanks for the comment askwho, but to be honest this is pretty basic stuff. Most of what you see in analog dirt boxes when it comes to the circuit is covered by 3rd semester electronics.

Ah, that figures...I need to polish-up on my op-amp theory a bit cause I think I'm a bit rusty, thanks for setting things straight for us paulc...cheers....

DrNomis · Post by **DrNomis** » 06 Sep 2011, 03:15

earthtonesaudio wrote:
DrNomis wrote:
askwho69 wrote:Thanks PaulC you're genius EAR and Idea... By the way can i ask what does the second Opamp do? like the pin 6 and 7?sorry im learning so need to ask

I just had a look at the schematic, the second op-amp has a gain of 1 (see where the two 3k3 resistors are?), the 3k3 resistor between pins 6 and 7 feeds the output of the op-amp into it's - input....

Second op-amp gain is TWO, not one.

The gain formula for a non-inverting op-amp is (1+Rf/Ri) where Rf=3.3k and Ri=3.3k.

My mistake, I got a bit complacent.....

Cheers.....

bajaman · Post by **bajaman** » 06 Sep 2011, 04:46

yes Paul

You are correct - it did have the pull switch on the back of the boost pot - now there's a nice vintage feature

it takes me back to the days of those early tube amps

.....and thanks for the insight into your future production thoughts for the pedal - most appreciated - thanks for sharing

I must say that there are many builders and dare i say it (solder jockeys) who are members of fsb and some of them are open and willing to discuss their products in a free and frank forum such as this, BUT, I do not think that any builder has ever given away his future thoughts for discussion, or correct another members drawings to ensure accuracy in such a polite manner before:shock:
Thanks for sharing your time with us all here.

Cheers
bajaman

DrNomis · Post by **DrNomis** » 06 Sep 2011, 08:36

bajaman wrote:yes Paul
You are correct - it did have the pull switch on the back of the boost pot - now there's a nice vintage feature
it takes me back to the days of those early tube amps
.....and thanks for the insight into your future production thoughts for the pedal - most appreciated - thanks for sharing
I must say that there are many builders and dare i say it (solder jockeys) who are members of fsb and some of them are open and willing to discuss their products in a free and frank forum such as this, BUT, I do not think that any builder has ever given away his future thoughts for discussion, or correct another members drawings to ensure accuracy in such a polite manner before:shock:
Thanks for sharing your time with us all here.
Cheers
bajaman

+1

Post by **bubstance** » 06 Sep 2011, 12:17

DrNomis wrote:
bajaman wrote:yes Paul
You are correct - it did have the pull switch on the back of the boost pot - now there's a nice vintage feature
it takes me back to the days of those early tube amps
.....and thanks for the insight into your future production thoughts for the pedal - most appreciated - thanks for sharing
I must say that there are many builders and dare i say it (solder jockeys) who are members of fsb and some of them are open and willing to discuss their products in a free and frank forum such as this, BUT, I do not think that any builder has ever given away his future thoughts for discussion, or correct another members drawings to ensure accuracy in such a polite manner before:shock:
Thanks for sharing your time with us all here.
Cheers
bajaman
+1

+2

Paul, you're the man.

p_wats · Post by **p_wats** » 06 Sep 2011, 15:44

This is a great thread, guys. I honestly opened it half expecting a dust-up because it's dissecting a pedal designed and sold by another member, but wow, paulc is a stand-up guy. I've only seen 2 builders as forthcoming and generous with their info: Paul and Doug Deeper. Makes me want to tell the world to buy from them.

Paul Cochrane - Tim pedal [traced]