Finally, I built a Tube Reamer with my 741

[Gilles C]

I used a stripboard, so I had to change the layout, and the board is 1" x 1.75", that's with a 14 pins socket. Fun little project to build.  

I'm still at work so I could only test it with a signal generator and a scope. But it's working well.

Tomorrow, I should be able to try it with my guitar and my amp. That will be the real test.  :twisted:

Thanks for the suggestion, the op-amp's been waiting in a drawer for 30 years. It was about time I did something with it.  

I'll tell you what I think about it with my amp and my Strat.

Gilles

[Fret Wire]

I think you'll like it. IMHO, it's livlier than a Tubescreamer, and more transparent. For diodes, I like the 4148/4001 combo.

BTW, the gain pot isn't really set up to increase/decrease gain. It just rolls off bass as you turn it up. Gain is max.

[Gilles C]

BTW, the gain pot isn't really set up to increase/decrease gain. It just rolls off bass as you turn it up. Gain is max.

:lol: I just used a jumper because I didn't have a pot with the correct value. So it's a good thing you told me. I will try it like that, and will add the pot later.

I used ge diodes, don't know the part number, just checked with a meter. It doesn't seem to have a lot of gain. Something like X2 or X2.5 at 1Khz.

But it seems to smooth the highs nicely. As long as I get the sound I heard in the sound clip at Runoffgroove... :roll:

Gilles

[Fret Wire]

If the Ge diodes kill a little too much high end bite, you could try lowering the 47pf cap down. It smoothes the highs pretty good with the Si's.

[Danny G]

Try it with a 50k gain pot.  I like mine ALOT with that upgrade, made a good pedal even better!  

As soon as I get my Marshall out of the shop I will continue the Tube Reamer/AMZ Mini booster death match!  Even if the Tube Reamer should be defeated, it'll still have a long productive life as a stand-alone distortion for my home practice amp!  

Great circuit, ROG!!!

[WGTP]

It's a cool feature the way the pot changes the roll off point of the cap depending on the resistance.  So both the gain and "voice" change.  

[Gilles C]

Try it with a 50k gain pot.  I like mine ALOT with that upgrade, made a good pedal even better!  
....
Great circuit, ROG!!!

Is that with GE or SI diodes?

'cause, with 50K, gain should go lower than the original pot I think :?

Gilles

[Fret Wire]

If my math is right, the 5k pot gives you a gain of 471-476, and a 50k pot gives you 471-521. That's why you really don't hear any gain change, just the bass rolloff. I didn't like it with Ge diodes as is, the 47pf cap dulls the highs too much, plus the lower output. Keeping with the "TS" flavor, I used a 4148/4001 combo, which sounded great.

If you want more gain range from clean to dirt, you'll have to adjust the .22uf/1k/5k pot/470k values to more of a TS type arrangement.

It's basically a Dist.+ with a "TS flavor", and no wacky biasing.

[Gilles C]

Hummm... I assumed that the gain formula was (if I don't add the cap value)

Gain min 1 would be = 1 + (470K / (1K + 5K) ) = 79 and
Gain min 2 would be = 1 + (470K / (1K + 50K) ) = 10
with a max of 1 + 470K / 1K = 471

so that's why I said the 50K would give me less gain.

Gilles

[Fret Wire]

I was thinking 1 + (5k + 470k/1k) = 476
                    1 + (470k/1k) = 471

[Gilles C]

Ok, I see.

Btw, I was able to try it this evening.

I still have only a wire in place of the gain pot, so it's the only sound I could try, but it's a good start.

Sounds good, but maybe a little too much bass, or not enough highs. And it cleans up when I lower the volume of my guitar.

I'll see when I add a gain pot how it changes the sound then.

I like it better than the TS-9 I once built and that had too much highs and was loosing too much bass. So I'll see what I can do once I have a gain pot installed.

Gilles

[MartyMart]

Had some chats with Fretwire over this a while ago, I wanted to be able to "clean up" the lower gain settings a bit, here's what worked for me:
1k and 470k to gain become, 1.5k and 120k or 150k,  gain pot becomes a 50k linear.
Gain pot is then clean 'til 11 o'clock, with nice increase there after.
Give it a try ?

Marty.

[Gilles C]

Interesting idea. As I once said, I play Blues, so I don't need extravangus distortion.  

I re-listened to the sound clips of the Tube Reamer, and re-evaluated my sound from that listening. The sound that I like is with max gain, less bassy. I prefer clip2 to clip1. And I like clip3.

So I need to add the 5K pot for sure.

The 50K gain pot was already an option I wanted to try, and a switch to select between a 470K and a 150K would be a nice addition to make. A Hi-Lo Boost switch looks good on a box...

Thanks for the suggestions.

Gilles

[gtech]

Ok, I finally tried it with a 50K in place of the 5K. It's going now from bassy to trebbly with more or less gain. And more and less distortion.

Had some chats with Fretwire over this a while ago, I wanted to be able to "clean up" the lower gain settings a bit, here's what worked for me:
1k and 470k to gain become, 1.5k and 120k or 150k,  gain pot becomes a 50k linear.
Gain pot is then clean 'til 11 o'clock, with nice increase there after.
Give it a try ?

Marty.

But I also tried a 150K and saw almost no change when I checked with a sine wave and a scope. I tried many values in parallel with the 470K and still got the same result. The ge diodes must do that. Right??

Gilles

[MartyMart]

Hi gtech,
I'm guessing that your scope somehow didn't show the circuit "clean up" ??
Thats absolutely the case with those changes, top range of the crunch seems the same, but backed off, the gain pot gives a much cleaner sound

I have the rest of the circuit "as is"  did you try the 470k becoming a 120k ?  perhaps 150k is enough to push the circuit back to normal ??
Just checked inside, mine is a 120k instead of the 470k

Cheers,
Marty.

[gtech]

Ok, that answer my question.

In fact, you're right. I checked the signal with smaller resistors but only with a distorted signal.

I was wondering if you had better results because of the si diodes.

I was a little rushed when I tried that yesterday, but I'll do the mods selectable with a switch this evening.

Thanks

Gilles

[MartyMart]

Thats great Gilles,
Let me know how you like it ?  its very nice just "backed off" a little.
I may try the "switch" myself !.

Cheers,
Marty.