MXR Microamp

[coelacanth]

Some noobie questions here. I'm getting the parts required to build a Microamp clone at present. Just some quick questions to ask you, gurus.

Looking at pedalpartsplus.com and smallbearelect.com now, but none of them carries the IC I want, TL061. Are there any equivalent substitutes that would work as fine? Or any single opamp would do? The other thing is that it uses a reverse log taper, 500k, and just wondering if log (or linear) would still work as fine with the circuit (because I've heard someone saying it here somewhere).

Thanks for your time in advance. Any help would be highly appreciated.

[Renegadrian]

There's a very interesting article about it on pisotones - http://www.pisotones.com/Dist+uAmp/Dist+uAmp.htm
use google traslator and you will be able to understand what they wrote...

[Ben N]

The TL061 is close cousin to the TL071 and TL081. From what I understand, they are all made the same, and just selected by spec--the TL081 is the base model, if you will, while the 071 is where the lower noise samples go, and the 061s have low current draw. So if you are planning on using an outside power supply, the best bet of the three is clearly the TL071, although there are other opamps, such as the audio quality Burr-Browns, that are also worthy of consideration (i.e. may be better) and are pin-for-pin substitutes in the circuit. Even if you are running on a battery, this circuit does not draw that much power, and the added life you would get with a TL061 may not justify the added noise (although, honestly, it's not much).

[alanlan]

I had an LF351 in mine which was good, but I don't know if you can still get 'em.

[Renegadrian]

Some layout use a 4558 too...

[coelacanth]

Thanks for the info guys. Really appreciated.

There's a very interesting article about it on pisotones - http://www.pisotones.com/Dist+uAmp/Dist+uAmp.htm
use google traslator and you will be able to understand what they wrote...

Thanks. Cool article, although there are some bits and pieces that I got a little confused.

In the MicroAMP we are talking of "Gain" which is nominally Alog 500K and for the Distortion +, the "Distortion" is nominally 1M Alog. Es practicamente imposible encontrar potenciómetros "Alog" de ningún valor (aunque ya los podéis comprar por correo ya muy buen precio en Musikding ) por lo que hemos de hacer algunas concesiones. It is practically impossible to find potentiometers "Alog" of no value (although you can buy and mail at very reasonable prices in Musikding) so we have to make some concessions. Lo más fácil es simplemente poner sus equivalentes lineales pero, creedme, váis a tener un 95% del giro practicamente inútil y todas las variaciones las tendréis en el 5% restante, lo que los hace muy poco prácticos de usar. The easiest is to simply put their equivalent linear but, believe me, you are going to be 95% of the money practically useless and all the variations you will have in the remaining 5%, which makes very little practical use. (translated by Google Translate)

So would that be fine to substitute that reverse log 500k with it linear equivalent? Would this do? http://www.pedalpartsplus.com/mm5/merchant.mvc?Screen=PROD&Store_Code=PPP&Product_Code=7512&Category_Code=Pot16

The TL061 is close cousin to the TL071 and TL081. From what I understand, they are all made the same, and just selected by spec--the TL081 is the base model, if you will, while the 071 is where the lower noise samples go, and the 061s have low current draw. So if you are planning on using an outside power supply, the best bet of the three is clearly the TL071, although there are other opamps, such as the audio quality Burr-Browns, that are also worthy of consideration (i.e. may be better) and are pin-for-pin substitutes in the circuit. Even if you are running on a battery, this circuit does not draw that much power, and the added life you would get with a TL061 may not justify the added noise (although, honestly, it's not much).

Not planning to use it with a battery, just as a backup perhaps. TL071 seems like a good choice, thanks!

[coelacanth]

one last bump

[Eric H]

one last bump

From a strictly electrical point of view, the various tapers and types of pots are completely interchangable.
a 500k pot looks the same to the circuit no matter what the taper.

However, as stated here:

"The easiest is to simply put their equivalent linear but, believe me, you are going to be 95% of the money practically useless and all the variations you will have in the remaining 5%, which makes very little practical use."

sometimes a linear (audio, etc.) will jam all the "action" from the knob in 5% of it's travel, making adjustment difficult.

I almost always use surplus linears, but sometimes find that I have to pull one and install the proper taper, a serious waste of time avoided by using the proper part the first time.
Go ahead and use the linear to get it running but don't be surprised if  "95% of the money practically useless"

You can also get an audio--taper, and reverse the wiring --but the control will then work backwards.
Sometimes that's an acceptable compromise...sometimes not ;-)

options, my friend ;-)


hope some of this helps,

-Eric

[lucasventura]

  Hi guys! I'm new here! I am Brazilian and would like to congratulate all the excellent work. I would say that recently did a booster based on the design MXR MicroAmp. I used a potentiometer and TL061 AMPOP 500KC, reverse log, as well as microamps. The response of this pedal, dubbed BOOSTER-C1 is faithful to the original sound of the guitar. I hope that you  like.

[lucasventura]

   
Hi guys! I'm new here! I am Brazilian and would like to congratulate all the excellent work. I would say that recently did a booster based on the design MXR MicroAmp. I used a potentiometer and TL061 AMPOP 500KC, reverse log, as well as microamps. The response of this pedal, dubbed BOOSTER-C1 is faithful to the original sound of the guitar. I hope that you  like.



An this is a 500kC pot,,