Timmy Update Verification

[GGBB]

I've been digging into the Timmy circuit lately and came across this site that documents a few of the changes over the years. None of the schematics I've come across show any of the improvements that have been made - they all seem to be of the first iteration. Most things described are easy enough to follow, but one I'm not 100% sure about.

The page references a Paul C. post at MadBean where he wrote:

The output stage had it's values changed from the stock 2x 3k3 w/4n7f setup to 2x 10k w/2n2f.

The 2x 3k3 in the output stage is shown in the "Timbre Reamer" schematic at the top of the manticorefx page - this is the schematic that all others seem to be based on. But there's no 4n7 cap in the output stage (or anywhere) in the schematic. If you look at the various gut shots and read the descriptions, the 4n7 cap doesn't show up until "v3" and in later gut shots you see a 2n2 in the same position.

I'm fairly sure that this cap must be between the op-amp output and inverting input, parallel to the first 3k3/10k - to smooth out the top end. I can't see it being in series with the second 3k3/10k to ground since that should cut an extreme amount of bass. Does that make sense? Or could it be somewhere else?

[Rob Strand]

I claim no prior knowledge regarding the Timmy details but based on links you gave, the web pages and the posts I think the idea is this:
- the schematic is for the hand-build one, which defaults to V1
- as you go down the page the changes in each version are elaborated.

So from what I can see the cap at the output stage is not present on V1 and so it is not present on the schematic, which is for V1.  However I can clearly see the parts 10k, 3k3, 2n2, 4n7 on the boards as you go down the page.


So I guess the beef is there's no cumulative log of the changes captured on the schematic.

The other changes are:
- treble pot taper change
- 39nF input cap change
- dip switch removed
- 47pf input cap

I don't know about the feedback circuit I've seen on one of the schematics.

[Elijah-Baley]

I built it using the tagboard layout. I always thought it was accurate, but these update... we whould track it again! Or maybe update the schematic reading all the information we can read in that page GGBB linked us.

[Rob Strand]

I built it using the tagboard layout. I always thought it was accurate, but these update... we whould track it again! Or maybe update the schematic reading all the information we can read in that page GGBB linked us.

I read over the manticorefx site and many of the posts around on the internet.  The manticorefx  site covers pretty much everything except the year the changes occurred and perhaps the colors of the boxes.

Paul Cochrane has been very open about the changes he has made over the years.

Most people on the internet call the earlier model without the toggle switch V1, regardless if it was the PCB version or the veroboard version.  I think it's better to stick with that or call the vero V1a and pcb V1b.

One thing I can add is V2 (Manticorefx V3) has the toggle switch.
The toggle switch is 3 positions:
Up  = Assymetrical ; don't know which polarity is 2 diodes and which is one.
Middle = Symmetrical Low Compression; 4 diodes, two up/ two down
Down = Symmetrical Most Compressed; 2 diodes, one up/one down

V1 has a no toggle switch and it has dip switches inside switch the diodes.   This configuration has two assymetrical modes, which probably sound identical.  I don't know which way the assymetrical diodes go on V2.

Also the version of the schematic on the web with the toggle switch is the V1 circuit where someone has added a feedback path (like Fulltone).   This is a DIY circuit and the switch does not do the same job as the switch on the Timmy V2.

From what I can see V1a, V1b and V2 were available in the purple/blue color.  After that they boxes changes color.  I don't know if the color corresponds to the circuit changes.

[antonis]

I'm fairly sure that this cap must be between the op-amp output and inverting input, parallel to the first 3k3/10k - to smooth out the top end. I can't see it being in series with the second 3k3/10k to ground since that should cut an extreme amount of bass. Does that make sense? Or could it be somewhere else?

There is a possibility for 4nF cap to be in place of 10nF cap (C7) 'cause that's the closer value existing cap on output stage..(although it makes no obvious sense to alter C7 value when altering feedback/gain resistors values..)
(can't recall neither the origin of the bellow schematic nor its version.. )

[Rob Strand]

There is a possibility for 4nF cap to be in place of 10nF cap (C7) 'cause that's the closer value existing cap on output stage..(although it makes no obvious sense to alter C7 value when altering feedback/gain resistors values..)
(can't recall neither the origin of the bellow schematic nor its version..

Your schematic is the early V1 schematic.

The V2 (manticorefx V3) circuit adds a feedback capacitor across the output and -ve input of the opamp to give it a bit of roll-off.  Later on he changed the 3k3 to 10k and reduce the feedback cap to 2n2.  (PC said it doesn't change anything but the scaling of the parts does shift the pole/zero frequencies).
The 10nF treble cap remains in all cases.

[Elijah-Baley]

I don't want to draw a new schematic now, but I can show this schematic because it has some useful indications:



So, the two 3.3k resistors in the last stage are now 10k, and if those indications are true increasing these resistor we should increase and decrease at the same time the volume, getting kind of the same volume?

And the new cap, 4.7nF early and 2.2nF now, goes in parallel with R6 (in the schematic I linked above).

Is it alright?

[Rob Strand]

I can show this schematic because it has some useful indications:

FYI, that schematic is OK for the general circuit shape but it has a *heap* of values which don't agree with the real thing.  The schematic antonis posted is much closer.  If you take antonis's schematic and put a 4n7 cap across the resistor R9.  Then put a switch on the diodes you would be getting pretty close.

So, the two 3.3k resistors in the last stage are now 10k, and if those indications are true increasing these resistor we should increase and decrease at the same time the volume, getting kind of the same volume?

And the new cap, 4.7nF early and 2.2nF now, goes in parallel with R6 (in the schematic I linked above).

Is it alright?

That's pretty much it.  The cap would be C8 in your schematic.   All units which had the 3k3+3k3+4n7 to 10k+10k+2n2 change also changed the treble resistor from 1k5 to 1k0 (R7 in antonis's schematic, R5 in yours). The 10k version has a little more roll-off at the opamp so Paul C shifted the treble cut-off frequency up so it sounded the same overall.

The only reason I'm interested in sorting this out is I've had all the different schematics sitting on my computer for several years.  I was pretty sure many were not the real thing.

I'd stick with the schematic antonis posted and update that.  Then use the manticorefx site to guide you to whatever version you want.   There's all the stuff about pot taper changes and adding resistors across pots.  It's all on that site.

If you want to be precise, there some minor differences in the schematics that need sorting out:
- On the later versions are the up and down diodes are cross-linked? like in antonis's schematic.
- On any of the versions, does the outer lug of the bass and treble control connected to the wiper.
- Which way the bass and treble controls pots work:  As far as I can tell, for the V1 circuit,  when the bass and treble controls are rotated clockwise the bass is *cut* and the treble is *cut*.   So from this perspective the bass pot on antonis's schematic is reversed (and the JAN RAY one you posted).  I have another schematic which has it going the "correct" way.  I don't know if this has been changed on the later versions.
- I'm pretty sure V1 units used audio taper pots for both Bass and Treble.
- The V1 units have a slightly different control layout arrangement:  the Gain control is top left and the Bass control is top right.  On the later units these get swapped and the toggle switch is added in the centre.

EDIT: Here's the link about the pot tapers, but I have a feeling the linear Treble pot taper is for a later model:
https://www.diystompboxes.com/smfforum/index.php?topic=119910.0

Yes, see here,
"The only change that's really happened to the pedals is the taper of the treble control which you noticed in one. It was changed from a 50ka pot to a 50kb around July 2012. It was right after the 1st run of surf greens when I changed it in all the pedals. With the old audio pot the critical area was bunched up between about 11 o'clock and 3 o'clock with not much going on with the last couple of settings on each end. The newer taper spreads it out more making it start to roll off quicker, and slow down when it gets darker - not as touchy as before."
https://www.thegearpage.net/board/index.php?threads/timmy-version-question.1444785/

[Elijah-Baley]

Thanks.
Yes, I posted the schematic just to have some indications about the parts.

I didn't noticed that extra 150pF!

And just to make the topic even clearer I can say that I built this:
https://3.bp.blogspot.com/-imI0JcQ_gSI/VAmT8yw-f3I/AAAAAAAAImM/MqxVruF6nCo/s1600/Paul%2BCochrane%2BTimmy%2BRev%2B2.png
Definitely the Treble and Bass pot work better if they are audio tape. Indeed, I ordered for a mistake two linear, but I could use just the first 30% about. And both the pots work like a "filter": you got max bass and max treble with the pots at minimum.
I have to look better the page you linked.

Then I built even the Jan Ray:
https://4.bp.blogspot.com/-Kl8c9Ob6p3g/U-vrtT1wGFI/AAAAAAAAIdI/JUibz5iBxD8/s1600/Vemuram%2BJan%2BRay%2BRev3.png
The layout wasn't exactly this, but Bass e Treble pots work commonly, indeed, they are connected differently from the Timmy layout.

[Rob Strand]

And just to make the topic even clearer I can say that I built this:
https://3.bp.blogspot.com/-imI0JcQ_gSI/VAmT8yw-f3I/AAAAAAAAImM/MqxVruF6nCo/s1600/Paul%2BCochrane%2BTimmy%2BRev%2B2.png
Definitely the Treble and Bass pot work better if they are audio tape. Indeed, I ordered for a mistake two linear, but I could use just the first 30% about. And both the pots work like a "filter": you got max bass and max treble with the pots at minimum.

As is, it's kind of a V1 with the DIP switch replaced by the toggle.  So it would need the 4n7 cap across the right-most 3k3 to make it like the earlier V2's; the first ones with the toggle switch.

As mentioned before, in later versions PaulC replaced the audio treble pot with a linear.  Linear treble pots are for units since July 2012.  From what I can see he hasn't added any parallel resistors on the linear Treble.  There's an extra resistor on the PCB for the LED, which I believe is for the LED, and the value changes a lot.  Some of the later PCBs have yet another resistor, located near the LED resistor, which was part of the 25KA +18k resistor Volume pot change; used since around 2015.

FWIW, I prefer log pots (backwards operating) or reverse log pots on those circuits.  If the frequency range is small then you can get away with linears.

[GGBB]

Thanks Rob for all the details and everyone for participating. Based on this and the trail of Paul C's posts noted in the manticorefx page, here's an updated schematic I'm labeling "2014" since that's the date of Paul C's post about the volume control change. If anyone spots an error please let me know.



EDIT: Drawing revised with corrections noted by Rob

I have a layout for etching if anyone is interested (not yet verified).

[Rob Strand]

Awesome.  Thanks!

I'm labeling "2014" since that's the date of Paul C's post about the volume control change. If anyone spots an error please let me know.

What I've discovered is the manticorefx site bundles the cap changes because PaulC posted them together but in production they didn't occur together.  The 39nF cap change occurred earlier.  The 47pF cap change is more difficult to narrow down.

This is my best efforts at the dates:
- Linear treble pots are for units since July 2012
- LM1458N    Mid(to Late) 2012 to Late 2014.  After that Reverts back to RC4559D
- 39n cap change in Aug 2016 PaulC says "That was done years ago"
  There's units with PCBs that have no holes for the RF cap but have 39nF and 1k treble.
  There's also units with 47n and PCBs with holes for RF cap but there is no cap loaded.
  I suspect the 39n vs 47n might have joggled about for a while.
- RF cap probably a bit after the 39n.

Anyway I fixed a few bugs:



EDIT:  On this I can add.
  I haven't seen a unit with the 18k volume resistor that doesn't have the RF cap.
  Provisions for the RF cap were on boards without the 18k resistor.
  So if your schematic covers the 18k resistor we don't have to worry about when the
  RF cap was implemented because it came before or at the same time.

  The 25kA + 18k volume change was maybe mid 2013.

BTW the dude in my pic is the real Tim (according to PaulC).

[Elijah-Baley]

Nice jobs, guys!
All this update is for what? To roll off some treble or what else?
I didn't get if there's a reason to change a bit the volume stage. Just to get a better tape?

The tagboard layout show the 4559 as IC, but I didn't try it because I used immediately the 1458 just because some guys said that it sounds really good.
What difference could make the 1458 vs 4559?

Just for comparing, Jan Ray sounded to me with smoother treble (indeed, it has C4, looking at the new schematic, but I guess it could be even a question of the setting, and I want to remember that the Timmy has more gain than the Jan Ray because the Gain pot 1M instead 500k on the Jan Ray, even without count the "two diodes mode", of course).
But now I don't have the Jan Ray for an accurate test, because it was for a friend. Anyway it should be

[Rob Strand]

ll this update is for what? To roll off some treble or what else?
I didn't get if there's a reason to change a bit the volume stage. Just to get a better tape?

I'm pretty sure the added cap is to take the edge off the nasty buzzy stuff around 5kHz and above.

PaulC did explain the reason for the volume mod.  He wanted it to have unity gain when the Volume pot was at 12 O clock; not sure where the other controls are set.

What difference could make the 1458 vs 4559?

Changing the opamps changes the high-end character.   It's very much a personal choice.   You could put just about anything in there and try it, NE5532, TL072, ...

Someone was saying PaulC wasn't happy with the consistency of the sound of the 1458's.  I don't know if that's true but I would not be surprised if some of the opamps these days sound different to the established "textbook" sound.   I haven't bought one for ages.  I have a lot of old stuff that has the "textbook" sound for each type.

[Elijah-Baley]

PaulC did explain the reason for the volume mod.  He wanted it to have unity gain when the Volume pot was at 12 O clock; not sure where the other controls are set.

I read it just now in a page you linked before.
Thanks Rob!

Changing the opamps changes the high-end character.   It's very much a personal choice.   You could put just about anything in there and try it, NE5532, TL072, ...

About the IC I'll try some different next time! Maybe trying to replicate the newer version.

[GGBB]

- flipped D1

Oops!    Good catch.

Thanks - my drawing has been updated as well.

[Rob Strand]

Thanks - my drawing has been updated as well.

Good stuff, thanks!  That should pin down what it really is.

FYI: While I was digging around I noticed from about mid 2018 there's units marked with '9-18Vdc' instead of '9Vdc' and also the Bass/Treble pots are being wired for clockwise = boost (which will probably require a reverse audio pot for bass). That's why I put July 2018 on my corrections.

Pin 3 of the gain pot is probably used (as shown in the schematic).  I found,
PaulC Nov 2007: "The gain pot is wired in from both outside legs - the wiper is not connected in the normal way."

[Rob Strand]

I found this interesting post by PaulC from 2007:

After elaborating much of the circuit in words.  In the exact same thread he posted this in regards to someone posting the schematic. 

" I'd rather it wasn't posted, but since i can't stop that I'd like it known it's not based on the reamer - it's based on the TIM which is 10 years old. These pedals are about half of the income my family has, and while you guys wont try to produce it for profit there are those that will. One guy already did last year , and had it up on ebay saying "looking for a Tim? Buy this - it's better". At least those guys should buy one from me to figure out instead of getting the info for free on the net. Is the right of the DIY guy to know more important than the finances of my family? "

In this 2018 thread where a schematic was posted he did not voice his objection and added more info

https://www.diystompboxes.com/smfforum/index.php?topic=119910.0



Should we remove the links or not?

[erio tedesco]

About opamp types:

https://www.diystompboxes.com/smfforum/index.php?topic=108876.msg995229#msg995229

Note Mark Hammer, Reply #9 on: October 23, 2014 :

"A fellow in town, on another forum, brought his Timmy (actual, not a clone) over, and we experimented with different chips.  he had read somewhere that the circuit liked the 1458.  We tried about a half dozen different types - CA3240 (possibly 3260), TL072, OP275, 4558, LM833, NE5532, and MC1458 - and the 1458 took it, hands down, largely because it rounded off the tone a bit, complementing the bright sound the pedal normally had.  I certainly wasn't expecting it to make a difference, but it did.

So why does the Timmy like a 1458 but the TS9 likes a 4558?  The Timmy tone control is a high-cut only, and not the cut-and-boost type the TS has.  It also has a higher clipping threshold.  So I'm guessing the limitations of the 1458 compensate for the extra headroom, and also supplement the high-cut."

[Rob Strand]

Note Mark Hammer, Reply #9 on: October 23, 2014 :

I tend to agree with Mark.   The thing to notice about the Timmy is it has gain after the low-pass filter and the gain stage (x2) has no low-pass filter following that last stage.  So if that stage clips you will be hearing the opamp.   Things like the tube screamer and Xotic AC/RC have unit gain with only the tone-control giving opportunity for post low-pass filter gain.  The BB is a little different as does have a post low-pass filter gain stage, however it's tied to the dual pot so it's only comes in at higher Volume settings.

After looking at Timmy with a clearer head, the low-pass filter added to the last stage on later versions doesn't filter the last stage if it clips so the opamp sound still gets through.

Some other well known "Transparent" pedals are the Clark Gainster (used opamp JRC072B) and Menatone Red Snapper (used opamp JRC4558D).  These have a second gain stage but they put the low pass filter *on* the second opamp.  So it's the same thing that second opamp has an opportunity to clip.   The thing to note is these use different opamps.  At the end of the day people tend to trim the high-end on the amp to compensate for the differences.  When you do AB testing with the same amp settings the units with less low-pass filtering, or brighter opamps will always sound harsher.