I’ve been using this circuit for years now (attached below), Overall, I’m really pleased with it, but I’ve recently learned that I can most likely swap the opamp to have the same audio quality but have my 9v battery last longer.
Quality is key for me though, I’m running clean guitar through this, and with as wide performance dynamics as can be gotten from a guitar (ie from very quiet passages to hard, percussive strumming). I’m happy with the sound of the circuit though, so if I can’t find another opamp of at least equal quality to the OPA2134, I’ll just keep spending the $$ on 9Vs.
Any recommendations?
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This following thread lead to this post: https://www.diyaudio.com/forums/instruments-and-amps/367418-9v-circuit-18v.html
I built the circuit in this thread: https://www.diyaudio.com/forums/ins...film-buffer-amp-combo-guitar-electronics.html
Here’s the circuit:
Quality is key for me though, I’m running clean guitar through this, and with as wide performance dynamics as can be gotten from a guitar (ie from very quiet passages to hard, percussive strumming). I’m happy with the sound of the circuit though, so if I can’t find another opamp of at least equal quality to the OPA2134, I’ll just keep spending the $$ on 9Vs.
Any recommendations?
__
This following thread lead to this post: https://www.diyaudio.com/forums/instruments-and-amps/367418-9v-circuit-18v.html
I built the circuit in this thread: https://www.diyaudio.com/forums/ins...film-buffer-amp-combo-guitar-electronics.html
Here’s the circuit:
Actually, in rereading my original thread, it was suggested that “LT1884 offers exceptionally low current draw while providing rail-to-rail voltage swing”, and that it might cut the battery drain down by 80%. So I think I’ll have to try this, but so far I can’t get the LT1884 locally, would have to order it online for approx $10 plus shipping. That might be a year’s supply of 9V batteries right there lol
Thanks for the recommendations @Passinwind and @papasteack
I'm not sure... I've never tried to solder the SOIC type... it's sounding pretty small though... any common practices to make this easier? Like some kind of socket adapter? I guess I'd just be a little worried about frying the internal components...guessing I'd need new tools like tiny heat sinks?
Another one recommended (on this webpage:Piezo Preamps) as an alternative to the OPA2134 was the NJM2068... which is very cheap in comparison. Not that my main concern is price... I just find it interesting how much these opamps can vary in price
I'm not sure... I've never tried to solder the SOIC type... it's sounding pretty small though... any common practices to make this easier? Like some kind of socket adapter? I guess I'd just be a little worried about frying the internal components...guessing I'd need new tools like tiny heat sinks?
Another one recommended (on this webpage:Piezo Preamps) as an alternative to the OPA2134 was the NJM2068... which is very cheap in comparison. Not that my main concern is price... I just find it interesting how much these opamps can vary in price
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I hand solder SOIC-8 parts quite a bit, depending on your experience and dexterity you may just need a relatively fine tip like 1.2mm or .8mm on a Hakko 888 or whatever. There are DIP-8 to SOIC-8 adapters readily available, one cost effective solution is through the circuit board share section at OSHpark. Personally, I've just ported the footprints on most of my DIY circuit boards to SOIC-8 and never looked back, as that's where so much of the new action really is.
Here's my latest DIY onboard bass preamp, using OPA2145 and OPA145, which is a candidate to end up as a non-commercial open source share in one form or another pretty soon:
That's all hand soldered with no specialized tooling beyond some decent tweezers and some skinny solder. I wouldn't want to mass produce this way, but for one-off hobby builds it works OK.
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Thanks for all the responses, info, recommendations, I've just been slowly making heads and tails of it. Cool to see your project @Passinwind, looks nice and clean, and small... great for an instrument.
Overall, it seems SOIC is looking the way to go... I'm thinking to try the OPA1692... buy a socket adapter and test it in my breadboard... worry about the actual installation later after I hear it.
Overall, it seems SOIC is looking the way to go... I'm thinking to try the OPA1692... buy a socket adapter and test it in my breadboard... worry about the actual installation later after I hear it.
I would be careful with soic parts not available in dip. Very often they need short traces to gnd and input pins to not oscillate near the transition frequency.
Especially with an adapter and socket the inductance of these lines is about 7 times higher also the pin to pin capacitance because of the socket.
An 8pin soic is easy to solder
Especially with an adapter and socket the inductance of these lines is about 7 times higher also the pin to pin capacitance because of the socket.
An 8pin soic is easy to solder
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Also, for the ease of it... staying in the DIP8 world, I'm thinking to try TL072. Or the "upgraded" version of that, the TLE2072.
I had tried the TL062, which almost worked, but heard the slightest bit of distortion on loud lows, but the TL072 is supposed to be the low noise version, so I'll try that. And if it's 2 mA that's still quite a battery savings compared to the OPA2134 at almost 8 mA.
I had tried the TL062, which almost worked, but heard the slightest bit of distortion on loud lows, but the TL072 is supposed to be the low noise version, so I'll try that. And if it's 2 mA that's still quite a battery savings compared to the OPA2134 at almost 8 mA.
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Gnobuddy liked the OPA145 - also part of the same family
"OPA145 is pretty hard to beat---still VERY miserly on power draw (~1/4mA each amp)
One can purchase adapters DIP for SOIC etc (note that double sided ones are a little tougher than single sided if your soldering is as rough as mine. I like to glue the little darlings down then solder two corners & then fill in the rest)
"OPA145 is pretty hard to beat---still VERY miserly on power draw (~1/4mA each amp)
One can purchase adapters DIP for SOIC etc (note that double sided ones are a little tougher than single sided if your soldering is as rough as mine. I like to glue the little darlings down then solder two corners & then fill in the rest)
The OPA1678 is another possible choice if you're willing to use SOIC (FWIW, I find SOIC chips very easy to solder) and you don't need extremely low power consumption. It's inexpensive, very low noise at 4.5nV/sqrt(Hz), and the quiescent current is half that of the OPA2134.
Edit: Looking at the schematic, I'd say the OPA1692 is a better choice overall than the OPA1678 unless cost is a huge consideration. The FET input of the OPA1678 doesn't really offer any advantages in this application and the OPA1692 has lower power consumption and similar performance otherwise.
Edit: Looking at the schematic, I'd say the OPA1692 is a better choice overall than the OPA1678 unless cost is a huge consideration. The FET input of the OPA1678 doesn't really offer any advantages in this application and the OPA1692 has lower power consumption and similar performance otherwise.
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