Amptweaker - Tight Metal  [traced]

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J0K3RX
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Post by J0K3RX »

Shouldn't be that loud... Try connecting the output jack directly to lug2 of the volume pot and see if it makes any difference with the overall volume. This has nothing to do with the volume issue but I believe R27 should be 4k7 instead of 1k5.

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Jan1966
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Post by Jan1966 »

You have done something wrong. Go over The circuit again. I have built loads of these.

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Post by Ichabod_Crane »

That resistor it's been replaced in the layout, so it's the 4.7k. :wink:

With the lug 2 of the Volume pot directy in the output makes almost any difference, I guess. The volume pot is still unusable, and in the first 10% boost a lot.

Even louer at lug 2 of the Tone pot and at the pin 1 of the TL072. Still loud, but with less distortion at pin 14 of the TL074.

Edit:
In the schematic the Tight pot has connected the lug 2 & 3. I connected 1 & 2, I guess it's just reverse.

TL072 voltages:
1 - 4.99v
2 - 4.99v
3 - 4.61v
4 - 0.00v
5 - 6.41v
6 - 6.50v
7 - 6.50v
8 - 9.00v

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Ichabod_Crane
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Post by Ichabod_Crane »

IC - TL074

1 - 4.99v
2 - 4.99v
3 - 4.70v
4 - 9.00v
5 - 5.85v
6 - 6.51v
7 - 6.51v
8 - 6.51v
9 - 6.51v
10 - 4.40v
11 - 0.00v
12 - 4.69v
13 - 4.69v
14 - 4.98v

I'm probing the circuit.
It sounds clean and ok until the first loop effect. Loose volume after R5 47.5k, still no volume at TL074 pin 2.
I got a volume boost at TL074 pin 1, the same volume at pin 10 and pin 8.
At TL074 pin 14 volume the same boosted but even slightly dirty sound.
At TL072 pin 2 I get more dirty sound
At pin 1 TL072 I got more distortion and more boost volume.

I think I never loose volume after it. No at lug 2 of the Tone pot, no at lug 2 of the Volume pot.

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Ichabod_Crane
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Post by Ichabod_Crane »

If the voltages are ok I don't see anything wrong. I have the temptation to use a B2k as Volume pot.

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Post by J0K3RX »

If there is no difference in volume when you wire lug 2 of the volume pot directly to the output then I think you should focus on IC2B and the surrounding componenet values and connections...

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Post by Ichabod_Crane »

I assume you mean there's someone in the last stage, so after the Volume pot, that should reduce the volume before the final output. :hmmm:

I'm looking at that now.

UPDATE
This is the corrected schematic (resized):
Image

Anyway, I can't find anything! :scratch:
R32, R33 and R34 are right and in the right position on the board.
Alright even C23 and C24.
Alright R35, C25, R36 and R38. R36 and R38 are in parallel and my multimeter show about 32k.

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Jan1966
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Post by Jan1966 »

Not sure if your schem is correct. There are a couple around which should be correct.
Or refer to storyboardist which is verified and compare to that.

http://effectslayouts.blogspot.com/search?q=Tight+metal
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TM.JPG

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Post by J0K3RX »

Ichabod_Crane wrote:R36 and R38 are in parallel and my multimeter show about 32k.
If you're not using the loop then one of those is not needed.. your choice R36 or R38.. 100k should be fine.

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Ichabod_Crane
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Post by Ichabod_Crane »

Jan1966 wrote:Not sure if your schem is correct. There are a couple around which should be correct.
Or refer to storyboardist which is verified and compare to that.

http://effectslayouts.blogspot.com/search?q=Tight+metal
Actually, I find out in your schematic a resistor (R8?) 1.5k. In all schematic I see a 15k.

Anyway, the schematic should correct and the layout verified.
J0K3RX wrote:
Ichabod_Crane wrote:R36 and R38 are in parallel and my multimeter show about 32k.
If you're not using the loop then one of those is not needed.. your choice R36 or R38.. 100k should be fine.
Indeed, I'm not using neither the first loop, so the same thing worth for R3 and R4.
But the Aeons by Grind Custom FX has none loops and has in the first loop a 320k resistor (like R3 || R4 -> 475k || 1M = 322k). This is why I got 32k with R36 and R38. 47k || 100k = 32k.
So, yes, I could leave out R4 and R38 (I see schematic with a 47k grounded before the output). But I have the doubt I can't solve the issue. Though I worreid about that R38 resistor.

Then, If my build is extremely loud, so should be Grind Custom FX's one?. :hmmm:

R36 and R38 can adjust the amout of volume? The only thing I think I have to do is to adjust that value (100k as J0K3RX suggested?) or add a trimpot as output volume. Or replace the B10k Volume pot with a B2k.

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Post by J0K3RX »

Hmm.. not really sure why you are getting such high output volume? You could go over it with an audio probe again and see if you can find where it jumps in volume.. :scratch:

Is this the Grind Customs schematic you used? Looks good to me but I only spent a couple minutes looking at it.
https://www.dropbox.com/sh/200s6g8gdcln ... ildDoc.pdf

On another note: I would be interested to see if the tight pot preforms any better if we relocate it between C4 and C5. As it stands the tight pot is useless in my opinion..

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Post by Ichabod_Crane »

The schematic used for the veroboard layout I used is the one I posted. The layout has the stock Tone pot and the charge pump is missing.

I already probed it.
Ichabod_Crane wrote:IC - TL074
[...]
It sounds clean and ok until the first loop effect. Loose volume after R5 47.5k, still no volume at TL074 pin 2.
I got a volume boost at TL074 pin 1, the same volume at pin 10 and pin 8.
At TL074 pin 14 volume the same boosted but even slightly dirty sound.
At TL072 pin 2 I get more dirty sound
At pin 1 TL072 I got more distortion and more boost volume.

I think I never loose volume after it. No at lug 2 of the Tone pot, no at lug 2 of the Volume pot.
I got the boost twice, pin 14 TL074 and at pin 1 TL072.
I see that the original Tight Metal is pretty loud, too. Sometime the volume pot is at 9 o'clock. Maybe my built is a bit more loud, I really can't see anything wrong, and maybe there's nothing wrong.

I guess a B5k pot could be more useable as volume, do you think it has also some side effect?

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Post by Ichabod_Crane »

Replace the 10k linear Volume pot qith a 5k linear. There's still an abrupt bump of volume in the very early part of the pot range.
Even when the volume pot of the Tight Metal is fully turn down I can hear the sound.

Looking at the schematic I'm using I have no sound at TL074 pin 2 and a big boost at pin 1. The R6 is a 1M and the orientation of D11 is right. What I have to check? Everything seems ok.
A 10k log pot (or a 5k log) could be adjust the range, but it's all so weird. :scratch:

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Post by Ichabod_Crane »

Replacing the 10k linear pot with a 5k linear pot the issue is NOT solved.

Could somebody probe the own Tight Metal to compare the volume in the varoiuos stages, please?

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Post by temol »

Ichabod_Crane - Maybe you should try to make another one TM, on a breadboard?

T.

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Post by Ichabod_Crane »

I am frightened that my breadboard is not so reliable for a big circuit. I could have problems.

My last chance will be to build it again, or maybe using this layout:
http://effectslayouts.blogspot.com/2015 ... metal.html
It's the same schematic, just a bit different in the order of the pin of the TL074. It is verified, except for the famous 4.7k, the layout is not update, but it's ok.
(A strange thing: an user built that protoboard layout and got the same issue wth the volume. With a different layout? :shock:

The veroboard I built should work, I really can't understand why it doesn't. Could be the TL074 from Tayda defective? Everything seems ok.
Actually, I prefered the veroboard layout becuase it's simple to build and I can modify, indeed I'm trying to replace the Trash switch with a Scoop pot. Almost done, but I got some problem. I followed the Aeons schematic, but maybe the problem is the position of the 220nF cap in the Scoop pot section. Maybe we could see it later.
The protoboard layout is a bit hard to build and to modify.

I'm trying to probe the circuit because I would like to understand where I get the unexpected volume boost, but I don't know what I have to expect without compare my circuit with a working circuit.

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Post by temol »

Ichabod_Crane wrote:I am frightened that my breadboard is not so reliable for a big circuit.
You have nothing to loose, just try it.
My last chance will be to build it again, or maybe using this layout:
http://effectslayouts.blogspot.com/2015 ... metal.html
I've built TM usung this layout, no problems with volume.

T.

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Post by Ichabod_Crane »

I used breadboard just for little circuit, sometime some contacts failes.
Anyway, I tried to redraw that layout you built to replace the trash switch and add the the Scoop pot. Indeed, seems even easier than mod the veroboard I found.

Image

I don't know if you tried something like that, but maybe we could:
1. Remove the 100nF close the the Return 2
2. Replace the 330R (Aeons by Grind Custom doesn't include it) with a 47nF cap.
3. Exclude, of course, the Trash Switch
4. Use the Scoop pot 100k Log
4. Trash SW 1 of the board goes in the Scoop 1
5. Trash SW 2 of the board goes in the Scoop 3
6. Scoop 2 to the ground

We should get the Trash sound with the Scoop pot full clockwise.

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Post by Daza »

I built the version of grindcustomfx and the one of brejna, in both I had problems with the volume, it is very strong.

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Post by Ichabod_Crane »

It's very probably my built is perfect, but I found at least three person with this problem. Though some people built thiese circuit withotu this issue.
There's some components that make the output volume so variable. ICs? Pots?
Where you, guys, bought the TL074, TL072 and the Potentiometers?

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?

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