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DIY Simple Active Preamp

j_loop said:
If I want to try the OPA2134 I should use the same adaptor as the AD823, correct
Click to expand...

Yes, any dip8 machined adapters with round legs like the one you posted a link too will work, just not the ones with the square legs.
 
Got this all put together a couple weeks and have enjoyed it tremendously! A definite step above the late 70's Japanese stuff I'd been using!
Haven't got the phono stages built yet...but almost. Can't Wait!!
Thanks Again!
 
j_loop said:
Got this all put together a couple weeks and have enjoyed it tremendously! A definite step above the late 70's Japanese stuff I'd been using!
Haven't got the phono stages built yet...but almost. Can't Wait!!
Thanks Again!
Click to expand...
You will love the phonostage too.

Regards
Sachin
 
I'm gathering parts for a Super Simple Preamp build and I'm having trouble finding the volume pot in the USA. Can anyone recommend a suitable replacement (preferably one you used) that can be purchased from a US vendor?
 
I´m in the process of building a new Super Simple Preamp, with a remote control for the volume.

I started a thread about it in the DIY forum.

Here are pics of my preamp board. I´m using Target 3001! V20 Discover CAD software. If anyone needs the files, just let me know. They are not tested yet, I´m waiting for the board to be etched.
edit: board, not boards


Anmerkung 2019-12-14 140123.png Anmerkung 2019-12-14 140159.png Anmerkung 2019-12-14 140243.png Anmerkung 2019-12-14 140308.png
 
Last edited:
I've lately been interested in trying low gain preamps and after reading about Rod Elliott's design here: https://sound-au.com/project88.htm I wanted to know if it could be made single stage. This great thread was a lucky find - it essentially answers that exact question. Thanks to all the contributors.

I just have to get a few more parts and then I'll be attempting to build this and a power supply on a perfboard. There are a couple of queries I have though as, unlike the first gain stage in Rod's preamp (above), the SSP omits capacitor C1 and resistors R1 & R2 at the input.

VtNBWr3.gif


Are there any cases that would require the use of the input capacitor (which I assume is for DC blocking) in the SSP?

The SSP has a potentiometer at each input. If those are not used then would R1 be reinstated? If I understand correctly, the value of this resistor is the input impedance.

Any clues as to what R2 does?

Sorry about all the questions. I'm not out to unsimplify the simple preamp, just further understand it. Attached is my proposed schematic for the SSP and PSU. If anyone has any comments on it they'd be appreciated.

2aYDviQ.png
 
Last edited:
Bodgeangles said:
I've lately been interested in trying low gain preamps and after reading about Rod Elliott's design here: https://sound-au.com/project88.htm I wanted to know if it could be made single stage. This great thread was a lucky find - it essentially answers that exact question. Thanks to all the contributors.

I just have to get a few more parts and then I'll be attempting to build this and a power supply on a perfboard. There are a couple of queries I have though as, unlike the first gain stage in Rod's preamp (above), the SSP omits capacitor C1 and resistors R1 & R2 at the input.

VtNBWr3.gif


Are there any cases that would require the use of the input capacitor (which I assume is for DC blocking) in the SSP?

The SSP has a potentiometer at each input. If those are not used then would R1 be reinstated? If I understand correctly, the value of this resistor is the input impedance.

Any clues as to what R2 does?

Sorry about all the questions. I'm not out to unsimplify the simple preamp, just further understand it. Attached is my proposed schematic for the SSP and PSU. If anyone has any comments on it they'd be appreciated.

2aYDviQ.png
Click to expand...

R2 (& 9) appear to be power regulation
 
Pio1980 said:
The Pass B1 is excellent, unity gain tho.
Click to expand...

Quite right,
Most often you don't need gain . Why many try passive preamps.

The B1 should give adequate drive that a passive might lack.
I've never been inclined to go the passive route. I do like simple though. I've found simpler amp and preamp circuits sound more organic to me. Obviously YMMV.

I recently finished an F5T and figured it'd like a family member in the mix. We'll see
 
nj pheonix said:
Quite right,
Most often you don't need gain . Why many try passive preamps.

The B1 should give adequate drive that a passive might lack.
I've never been inclined to go the passive route. I do like simple though. I've found simpler amp and preamp circuits sound more organic to me. Obviously YMMV.

I recently finished an F5T and figured it'd like a family member in the mix. We'll see
Click to expand...

Indeed. I'm actually running a buffer at the moment into an Aleph J. It is an Aikido line stage which I converted to be a just a cathode follower, but before that it had a gain of about 9 with 6N6P tubes. 16 if the first stage used 6DJ8s.

I find I don't need any gain for most things, but have hit the top of the volume control for very quiet material. The usable adjustment range is quite narrow too.

I'm interested in experimenting with a simple gain stage to see how much might be just enough.
 
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