# Caline Pure Sky



## isoneedacoffee (Oct 31, 2014)

I realize that the Pure Sky is based on the Timmy. However, there may be important differences that I was hoping owners of the Pure Sky could comment on.

*Let's please leave the moral issue about buying clones for another thread.*

1) It doesn't have a way to switch chips, so what chip does the Pure Sky come with stock?

2) The treble/bass knobs function traditionally, and don't do the "cut" thing that the Timmy does. Would my EQ control be in any way compromised through this set up?

3) Finally the bass/treble tone knobs are set up in the Timmy as pre/post overdrive respectively (if I remember the order correctly). Would that be the same in the Pure Sky.

Ultimately, I think I would be using it at the end of my chain (before time effects) as an "always on" pedal for slight dirt. Before it, I would have stacked an Xotic Sl Drive. I am very interested in the EQ, tone-shaping, capabilities of the Timmy from what I have read online. I wouldn't want this compromised very much if I get the Pure Sky rather than the Timmy.

For those who would say "Just get a Timmy," I hear you... and I might. But, right now the Timmy is $129 (US), whereas the Pure Sky is $30 (US).

Thanks.


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## mhammer (Nov 30, 2007)

Chinese clones of boutique and "classic" production pedals are everywhere, nothing new, and nothing to be ashamed of.

The Timmy bass control adjusts how much bass is provided to the clipping stage. A conventional TS-9 and SD-1 cut the bass significantly to provide a more "even" clipping across the fretboard. The Timmy allows you to dial it back in. It does NOT boost bass as your Xotic probably does (though I'm guessing about the Xotic). The stock TS-9 and SD-1's tone control provides for treble/mid boost at one extreme, and treble cut at the other. The Timmy's Tone (and probably Pure Sky's Treble) shaves off highs after the clipping stage.

How can you tell if the Bass and Treble controls work the same way on the Pure Sky, thus indicating a circuit highly similar to the Timmy? For starters, you should likely hear more breakup on lower strings than higher ones as the Bass control is increased. You can also expect this to interact with the Gain control. Second, the Treble control should not provide any treble boost, only cut. This would mean that with the Gain turned down, the action of the Treble control would appear fairly subtle.

Note that the Timmy has a toggle switch to select between clipping modes, and the Pure Sky doesn't. I have no idea whether there is any dipswitch inside to make such a change. Perhaps you could let us know if there is, and/or also how many diodes you see clustered together. Alternatively, if you can take a picture of the component board and post it here, that might provide the information.


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## isoneedacoffee (Oct 31, 2014)

Thanks for the reply mhammer. I ended up getting a Timmy so I'll never see the guts of the pure sky. I'm still interested however in hearing from people who have a pure sky.


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## traynor_garnet (Feb 22, 2006)

Mine arrived this week and it sits right beside my Timmy. They sound the same. Sure the pots are not reversed and there is no clipping option (I perfer the standard Timmy setting anyway), but they sound the same.

Glad you bought from Paul C. He is an amazing guy and deserves support.

TG


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## isoneedacoffee (Oct 31, 2014)

Thanks for the info TG. Do you know what chip is inside the pure sky? By the way, where did you order it from? I might also be interested in the future.


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## traynor_garnet (Feb 22, 2006)

I haven't had a chance to open it yet and take a look. I just got it two days ago.

I ordered from Donner. I was just curious to hear it and wanted to try out two Timmies on my board. If I stick with using two, I will order a second Timmy from Paul.

TG 



isoneedacoffee said:


> Thanks for the info TG. Do you know what chip is inside the pure sky? By the way, where did you order it from? I might also be interested in the future.


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## mhammer (Nov 30, 2007)

One of the forum members brought his Timmy over, and we auditioned probably a half dozen different chips. Much to my surprise, we both agreed that a 1458 sounded best, and better than what the pedal came with. I was surprised because I usually don't expect chip changes to make a difference, but in this case it sanded down the rough edges of the tone in a pleasant way, largely because of what would normally be its limitations in many other contexts. Can't remember if it was a Motorola or NatSem chip, but that shouldn't make a difference.


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## traynor_garnet (Feb 22, 2006)

mhammer said:


> One of the forum members brought his Timmy over, and we auditioned probably a half dozen different chips. Much to my surprise, we both agreed that a 1458 sounded best, and better than what the pedal came with. I was surprised because I usually don't expect chip changes to make a difference, but in this case it sanded down the rough edges of the tone in a pleasant way, largely because of what would normally be its limitations in many other contexts. Can't remember if it was a Motorola or NatSem chip, but that shouldn't make a difference.


i flipped a bunch of chips and preferred the stock one. My guess is it will depend on the amp. 

TG


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## isoneedacoffee (Oct 31, 2014)

TG I'm running a yba1. If I recall correctly that's what you're running too right? I ask because the Timmy I ordered comes with LN1458 chip. I have thought about ordering the stock one as well just in case.


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## mhammer (Nov 30, 2007)

traynor_garnet said:


> i flipped a bunch of chips and preferred the stock one. My guess is it will depend on the amp.
> 
> TG


That, and settings.

We did our demoing through a tweed Princeton with an SC-equipped guitar. I can see where a player using an HB-equipped guitar into a warmer amp might want the additional edge a different op-amp might provide. In our case, the limitations of the 1458 provided a welcome limit on the top end.


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## traynor_garnet (Feb 22, 2006)

isoneedacoffee said:


> TG I'm running a yba1. If I recall correctly that's what you're running too right? I ask because the Timmy I ordered comes with LN1458 chip. I have thought about ordering the stock one as well just in case.


Yes, a very early tube rectified bassmaster, Strat, running the Timmy at very low gain. Sounds amazingly open and just like the amp does when it _is __just _breaking up. The chips are dirt cheap, so why not add one.

TG

- - - Updated - - -

How much dirt were you using? I use mine for just a hint of od (about 10:00 on the gain knob) and found other chips change the openness of the top end and the pedal became more compressed sounding.

TG



mhammer said:


> That, and settings.
> 
> We did our demoing through a tweed Princeton with an SC-equipped guitar. I can see where a player using an HB-equipped guitar into a warmer amp might want the additional edge a different op-amp might provide. In our case, the limitations of the 1458 provided a welcome limit on the top end.


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## isoneedacoffee (Oct 31, 2014)

Ill be using the Timmy with both a strat and a hb guitar. So thanks for the info guys. TG when you look inside the pure sky please let us know what chip it has and if it is socketed.


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## Tarbender (Apr 7, 2006)

You guys got me curious so I opened up my original Timmy (about 10 years old) with the cream board and the internal symmetry switch to find 4559D chip. I've also got a newer Timmy with the green board and external switch, (about 2 years old) and it has the same chip. Has this chip changed over the years?


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## isoneedacoffee (Oct 31, 2014)

Tarbender the chip hasn't changed. The stock one has always been the one you have (from what I understand). There have been however some special runs made for Humbucker Music for example that had a different chip. But because the chip is socketed people have been experimenting with different ones for awhile.


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## mhammer (Nov 30, 2007)

The 4559 is certainly a quieter chip, as far as noise specs go, and that certainly counts for _something_. As far as I know, nothing about it has changed in the last decade.

The chip-tasting session that resulted in swapping the 4559 for a 1458 was prompted by the pedal owner reading something in TGP or somewhere that a 1458 sounded better. I don't recall what sort of board he had, but there were only 4 knobs and no toggle. I removed the stock chip and installed a socket for chip-swapping.

A quick tutorial on "gain-bandwidth product". YOu can usually find a graph showing this in the datasheet for almost any op-amp.

When you apply gain to an audio signal, you are asking the amplifying device to swing back and forth, because it is amplifying and AC signal. While the device can manage to swing back and forth very quickly when it is only being asked to apply minimal gain, as the gain is increased, the device runs out of swinging capacity for higher frequencies, even though it can still swing wide for low frequencies (where the amount of change in the output is slow enough for the device to keep up). Because this decline in ability to produce gain occurs with increasing frequency, we see it described as "gain-bandwidth product" in the datasheets, and shown as a graph, plotting where the high frequencies start to lag at different gain settings.

Why does this matter to us? Because when a chip is used to produce non-boost effects (e.g., in a phaser or delay), things like its noise specs matter more to us than what it does at gain levels well above what such pedals would use. When employed in overdrive, we are often asking it to go right out to the limits of usable gain.

Many overdrive circuits will attempt to achieve gains in the range of several hundred, to under 1000. Because harmonics of harmonics rarely sounds good, we tend to like a warmer overdrive sound pushing an amp. In such circumstances, the notion of a chip whose gain-bandwidth product is modest (i.e., it can't produce much gain without losing steam for high frequencies) is a welcome thing. It may be a lousy chip to use in something like a mixer, but in an overdrive pedal, less can often be more.

The 1458 has a modest gain-bandwidth product.


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## Tarbender (Apr 7, 2006)

Thanks for the info guys. 

mhammer, your explanation is great. I'm going to check out my chip drawer and see what I have to experiment with.


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## Tarbender (Apr 7, 2006)

Another curiosity, I just cracked open a clone TS-808 to discover a 4558 chip. I guess these are a popular chip family for this kind of application.


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## mhammer (Nov 30, 2007)

Not just ANY 4558, but the mojo trail_ obliges _a JRC4558D. This is not a particularly rare or special chip, but people place a great deal of faith in it; enough that a lot of ad copy for clones stresses the inclusion of this particular chip, suffixes and all.


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## Tarbender (Apr 7, 2006)

And that is the precise chip that I have in this clone. I bought this off a builder up in your neck of the woods - Goudie FX. So if I was to take the 4558 chip from the TS808 and swap it with the Timmy's 4559, would the Timmy sound more like the 808 or would I hear any difference at all?


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## mhammer (Nov 30, 2007)

My feeling is that the "soul" of the pedal does not lie in the chip used. Op-amps are meant to be colourless. As I hope I was able to convey earlier, whatever colour they impart tends to result from being forced to run up against their limitations.

If I understood Jack Orman's comments from well over a decade ago, the "specialness" of the 4558 in the TS-808 results from the way it adapts to feedback through the diodes. IIRC, he felt that any of a number of other op-amps could be used by sticking a small resistor in series with the diodes, though I forget the particulars.

In any event, the TS-808 has a more "compressed" sound to it, and that results from the use of a 1+1 diode pair, rather than a 2+2 as the Timmy uses. That will supercede whatever the chip imparts. Which is to say that a Timmy will still sound like a Timmy and an 808 like an 808. There might be very slight differences in the tone at highest gain settings, resulting from the change of chip, but those differences could easily be obliterated by a change of amp or pickups, or simply Tone control setting on the guitar.


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## Tarbender (Apr 7, 2006)

Makes perfect sense to me. Thanks again for the education


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## traynor_garnet (Feb 22, 2006)

I took the back off to check out the chip but you cannot see it without totally disassembling the pedal. I don't want to screw it up so I just put it back together. 

Sorry,
TG


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## isoneedacoffee (Oct 31, 2014)

Thanks for trying TG. It looks like the real Timmy has some definite tonal shaping advantages over the pure sky (leaving aside any moral prerogative).

I'll be getting the 4559 to experiment with. Should I stay away from anything? Some items say 4559 and some say 4559D some are Jrc and some are not. Do I need 8 pins? If I find what I'm looking for (jrc4559d?) does it matter if I buy the cheapest one on eBay?


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## mhammer (Nov 30, 2007)

A 4559 is a 4559 is a 4559. NJM = JRC (same company) As near as I can tell, only two companies make a 4559, JRC and Texas Instruments (RC4559).

You can see a datasheet for the NJM/JRC one here: http://www.njr.com/semicon/PDF/NJM4558_NJM4559_E.pdf

If you look in the upper left-hand corner of page 3, you'll see a graph showing the gain/bandwidth product. They label it "open-loop gain"; a common name for the same thing. The graph compares a 4558 (blue) and a 4559 (black). If you look at around the 45db mark (a gain of 177x, which is rather common for an overdrive, though halfway between a TS-9 and a DOD250 at maximum gain), you can see that the 4558 tops out at around 11khz bandwidth, which the 4559 can still deliver around 15khz bandwidth. At 60db (1000x, which IS high), the 4558 will get you around 3khz usable bandwidth, while the 4559 gets you 7khz.

Note that it's not that the chip delivers nothing above that point, but that it will be flat below those reference points, and roll off significantly above them.


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## isoneedacoffee (Oct 31, 2014)

Thanks mhammer! I was hoping you'd respond. Boy, this thread has been educational for me!


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## mhammer (Nov 30, 2007)

Glad to help. Incidentally, you can usually find a datasheet for just about any chip or transistor you want by entering the part number and "pdf" (since the datasheets are always in PDF form. So, "LM1458 pdf" in your favourite search engine will get you the datasheet for the 1458 dual op-amp.

Note that some datasheets will have slightly different information than others, depending on the manufacturer and the age of the datasheet. So a more recent one might forego all the graphs, but provide more information about different package types, or the measurements for those interested in robotic assembly of circuit boards.

Similarly, though not the case with chips, transistors, and especially JFETs, can sometimes have different pinouts, depending on the manufacturer. Or they may have the same pinout, but one manufacturer's drawing leaves you scratching your head about whether the pins they show are lokking down from the top or looking up from the bottom. In such instances, it is helpful to download datasheets from a few manufacturers, since one of them may have a much better 3-D illustration that provides certainty.

Bottom line: they're free and easy to find, so snag a bunch for whatever you're interested in knowing more about.


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