Amptweaker - Tight Metal  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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sixthfloor
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Post by sixthfloor »

Ichabod_Crane wrote: And I want to ask how solve this issue? Replace the volume pot with another value, maybe log? Or use a resistor or a trimmer and add an alternative volume pot in the end of the circut?
I've taken a look at the schematic (version 3g) https://www.freestompboxes.org/download/ ... &mode=view, and I think reducing the value of R27 would reduce the overall volume.

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Ichabod_Crane
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Post by Ichabod_Crane »

Thanks, sixthfloor! :wink: That is one of the thing I taken on count but I still didn't touch.
The PAD 3 & 4 (as the PAD 1 & 2) are jumpered to exclude the two loops effect.
So we have R27 in parallel with R28: 47k || 100kk ≃ 32k. The same trick on the Aeons by Grind Custom FX built, which has 33k, so it is pretty the same value of my schematic.

At this point is easier for me with this layout replace R28 100k with a 12k, and get 47k || 12k ≃ 9.6k.

Does this reasoning make sense?

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sixthfloor
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Post by sixthfloor »

You're welcome Ichabod ;)

I assume you mean R38 (100k between out1/pad4 and ground) rather than R28 which is in the power supply section. So yes, lowering either R27 or R38 should reduce the output volume.

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Post by mnemonic »

I made a version this week on veroboard using this layout:

http://guitar-fx-layouts.42897.x6.nabbl ... d9212.html

And I’m not having any volume issues, it seems to be about the same as most other preamp pedals I have (ISP, AMT, etc). I guess you could compare that layout to what you have?

Image Image

Kind of a rats nest, I need to work on wire management with veroboard.

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Post by Ichabod_Crane »

That issue is really strange, though with me also Daza got it with two different layout. And I read about another user on http://effectslayouts.blogspot.com/2015 ... metal.html, but reading better I guess he had some other problems with the circuit, not just the "insane volume".

I built the layout with the external Gate control, and even this should be verified, and it is just a little bit modified to have a easier wiring of the Gate pot.

So, or there's something wrong with the layout I opted, or there something in the component I used.
I used ICs and pots from Tayda. As well the resistors and the caps, but I cannot see how they can influence the volume.
What about the 1N4733? From Tayda, again. I think those are in a critical spot about the gain and the volume of the circuit.

I still didn't try to replace the R38 100k (NOT 328, indeed). I really afraid that it will change nothing. I hope I'm wrong. :shock:

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Post by Ichabod_Crane »

I finally replace the R38 100k with 15k, then 12k and then 8.2k, getting less than 7k. The volume is pretty the same. Using a 680R :shock: I got a bit of volume cut and a resistor really low, close to 680R, but I cut low range and fatness, and the sound is now nasal.

I'm going to restore the 10k volume pot (I replaced it with a 5k), but probably I will not solve the issue.

This thing is absurd! :scratch:

Edit: I just replaced the TL074 with another, (bought always from Tayda, but the text printed on it looks different). And replaced the TL074 with a NE5532. Volume is always the same.

How I can fix this?

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phatt
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Post by phatt »

I'm not about to plow through 30 pages but have you considered that one or more of your resistors could be the wrong value or worse mis labeled.
If you are using metal resistors with the Blue base colour then they can be hard to read.
I'm not colour blind but I struggle to read those. :twisted: I often have to double check with meter to make sure. :roll:
The old cream base coat made it so much easier to read.
Also I once purchased resistors that were labeled wrong so it can happen so worth checking.
Phil.

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Post by marshmellow »

There are several possible adjustments to decrease volume.

- R25 bigger
- R15 smaller
- R26 bigger
- Insert a resistor between C16 and the volume pot

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Post by Ichabod_Crane »

phatt wrote:I'm not about to plow through 30 pages but have you considered that one or more of your resistors could be the wrong value or worse mis labeled.
If you are using metal resistors with the Blue base colour then they can be hard to read.
I'm not colour blind but I struggle to read those. :twisted: I often have to double check with meter to make sure. :roll:
The old cream base coat made it so much easier to read.
Also I once purchased resistors that were labeled wrong so it can happen so worth checking.
Phil.
Thanks phatt. I always measure the resistors before to solder them, and after. And I measured them on board at least three times without to find strange values, though some resistors, because the caps, their value risen up slowly.
I can't measure the caps because my multimeter doesn't have that function.
marshmellow wrote:There are several possible adjustments to decrease volume.

- R25 bigger
- R15 smaller
- R26 bigger
- Insert a resistor between C16 and the volume pot
(This valure follow the last schematic linked).

Thanks, I'll try, because now I'm really hopeless. I wish this mods don't change the tone, but just the volume.
I would ask something more: Those three resistors determine the volume. So probably I'll check them out in case of mistake or kind of. Are there are further parts that could cause this highest volume?
I suppose R6, R17, but maybe that determine the gain, too. What about the diodes 1N4733.
I can't think about none other parts.
I find several boost in almost all the stages, especially after the second "triangle" and the fifth "triangle".
Could someone probe the circuit, please?

Probably I'll try to breadboard it or rebuild it maybe using the layout with trimmer for the gate. But If I don't found the mistake (if there is, a mistake) I'm really afraid to get the same strong volume.

The sound is really ok, its like a really big hi-gain amp, really close to the metal and whatever tone. But this volume is dangerous and unmanageable.

Thanks to all.

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J0K3RX
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Post by J0K3RX »

The 3g schematic is 100% correct. I have built too many to count using that schematic and I know many others have also without any issues. If you and others are reporting high output volume and you are all using different layouts then what do they all have in common?

I can tell you as a rule, I will not buy/use any parts from Tayda besides resistors and maybe caps... I just don't need the aggravation and uncertainty that counterfeit components bring to the process! I don't have any spare time in my life to waste snipe hunting my builds only to find the problem was a fake ass junk part! What's worse than buying fake parts? I will tell you... Wasting my mother f%#king time only to figure out that the problem was a Tayda counterfeit POS!

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Ichabod_Crane
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Post by Ichabod_Crane »

Thanks for reply, J0K3RX.
The schematic used for that veroboard layout is the same of 3g linked above (except for a resistor near the 33nF and the Tight pot, 1.5k instead 15k, myabe that 3g schematic was an old version. In the layout I used there is a 15k). Anyway, the veroboard layout is verified, as show us mnemonic, (the one with gate trimpot on board). But my version is verified, too.

I don't know if the problem is some parts of Tayda, I don't have any proof that the Tayda's components I bought are fake. I used in the past the same components and the effect worked. Yesterday I replace three ICs I have in the stock, without solve.

In this moment I'm really frustrated, I just would like to spot the problem. Now, I think there are less chances that the problem are the ICs. I'm not an expert, not at all, but I don't think that neither the resistors and caps could be cause this boosts (excluding some wrong resistors value that I didn't find). My doubt, and maybe I wrong, is in the 1N4733s. Spotted in a critical position about the boosting, I guess. First time I buy them, look normal if I see image on the web. I used my multimeter to measure the forward voltage, and I get about over 0.700v, even soldered on board.

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Post by J0K3RX »

Tayda has no certifications and therefore no guarantees that you are getting genuine components... That means they are sourcing the parts they are selling from wherever they damn well please. There are some small resellers that don't have industry standard certifications but they pride themselves in delivering authentic high quality components. Tayda is not one of them. Bottom line is if your supplier does not have the industry standard certifications such as AS6496, AS9100C etc.. then you run the risk of buying inferior components that have been rebranded to look like the component you ordered.

https://www.aeri.com/counterfeit-electr ... detection/

I ordered about 20 TL074's from Tayda and they were all fake. Compared them to the TL074's that I got from mouser and the differences were visually and electronically obvious. I am not saying that this is why you are having issues but to just assume that it's not the reason is foolish.

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Post by Ichabod_Crane »

I'm shocked! Nevertheless, there are many people who buy on tayda :shock:

As you said, maybe there's nothing to do with my issue, but after this I don't know if I can buy IC, transistors or diodes from Tayda.
We are in off topic but actually, I noticed that 2N5088 and 2N5089 are never over 260 hfe. Or 1N914 from Tayda looks different from the ones from Musikding.

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Post by Ichabod_Crane »

I did just one attempt to mod the volume. I didn't consider the resistor on the board, because (holy crap!) they are correct.
I insert a flying resistor between the lug 3 of the VOlume and the wire. A 47k. And it seems work fine! :D The volume is lower and I can't hear eny difference in the sound (Should I?). I'll calibrate a bit the amount of the resistence, but finally it should fix this weird issue.

Thanks to all, and thanks again for the trick, marshmellow! :wink:

Now, I have to handle the Scoop Pot mod, because following the Aeons schematic I had some problem, instead if I move the 220nF cap close to the 47nF (or where the 100nF original caps were) I can get the expected result.

I just change my mind about the charge pump. I misunderstood this detail, I thought the original has it, but probably not.
What benefit should the charge pump give to it? I think more dynamic and definition? But I think also less gain, even if the Tight metal has tons of it.
If I don't find any reason good enough for my taste probably I'll make the charge pump for another pedal.

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Post by Ichabod_Crane »

Hi, I still have to try better the resistor before the Volume pot. I have the feeling that the frequency change a bit. :roll:

Menawhile, I tried again the include the Scoop pot with the same unespected result I got early.

Looking at this schematic: https://www.freestompboxes.org/download/ ... &mode=view I could say I left out C13, the trash switch and R22.
Looking at the Aeons schematic I replaced C15 with a 47nF cap getting a dark and fat sound, then I tried the 220nF, getting the trash mode of the Tight metal.
So now I include the two caps C15a 47nF that goes in the lug 1 of the Scoop pot and C15b 220nF that goes in the lug 3 of the Scoop pot. Lug 2 goes to the ground.
It's all ok when the pot is at min (0k for 47nF), but when the pot is almost at max (0k for 220nF) the sound stop to shrill how could be in the trash mode and gets dull when it's at max.

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Post by moonshiner »

Ichabod_Crane wrote:I'm shocked! Nevertheless, there are many people who buy on tayda :shock:

As you said, maybe there's nothing to do with my issue, but after this I don't know if I can buy IC, transistors or diodes from Tayda.
We are in off topic but actually, I noticed that 2N5088 and 2N5089 are never over 260 hfe. Or 1N914 from Tayda looks different from the ones from Musikding.
I have bought hundreds of all of the above. The 2n5088 test between 400-550hfe the 2n2059 test between 525=680hfe. I have never recieved a bad part from Tayda.You might have an issue with your tester. I had a bad tester when i first started Harbor Frieght tester was bad, Even the pt2399 are great i bought a bunch off ebay and they were bad must have been factory rejects.

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Post by moonshiner »

moonshiner wrote:
Ichabod_Crane wrote:I'm shocked! Nevertheless, there are many people who buy on tayda :shock:

As you said, maybe there's nothing to do with my issue, but after this I don't know if I can buy IC, transistors or diodes from Tayda.
We are in off topic but actually, I noticed that 2N5088 and 2N5089 are never over 260 hfe. Or 1N914 from Tayda looks different from the ones from Musikding.
I have bought hundreds of all of the above. The 2n5088 test between 400-550hfe the 2n2059 test between 525=680hfe. I have never recieved a bad part from Tayda.You might have an issue with your tester. I had a bad tester when i first started Harbor Frieght tester was bad, Even the pt2399 are great i bought a bunch off ebay and they were bad must have been factory rejects.
Diodes can perform the same function and be a different casing. I did notice the 1n34a diodes are in a 1n270 body. I actually like them though. I prefer 1n4148 over the 1n914 diodes for clipping diodes.I make a pedal that sounds best with 650 hfe transistors . I bought 50 2n2059 and 35 of them were right at 645-655hfe.

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Post by ElPedro1970 »

Has anyone cracked open a fat metal to see what differences there are between it and the tight?

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Post by J0K3RX »

ElPedro1970 wrote:Has anyone cracked open a fat metal to see what differences there are between it and the tight?
I haven't seen any gut shots for the fat metal, fat rock but, they use the same board as fat metal. On the tight rock pro there are extra caps that aren't populated so my guess is the differences would be extra caps, different cap values and resistor values between the tight metal and fat metal, fat rock etc... The differences between the tight rock and tight metal are no more than couple cap and resistor values so why mess with success...

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Post by J0K3RX »

J0K3RX wrote:
ElPedro1970 wrote:Has anyone cracked open a fat metal to see what differences there are between it and the tight?
I haven't seen any gut shots for the fat metal, fat rock but, they use the same board as fat metal. On the tight rock pro there are extra caps that aren't populated so my guess is the differences would be extra caps, different cap values and resistor values between the tight metal and fat metal, fat rock etc... The differences between the tight rock and tight metal are no more than couple cap and resistor values so why mess with success...
What I meant to say: :slap:
I haven't seen any gut shots for the fat metal, fat rock but, the fat rock uses the same board as tight rock. Since there is little difference between the tight rock and the tight metal it would lead me to believe they are the same as well.
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