Easy! Tell her just what I told my wife long time ago. "One for each genre!" Just kidding of course. They already know your addiction. No point in hiding it. Great build by the way. One of the best I have seen here!
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While I was admiring your build, I thought those diodes on your preamp-source-selector-board where looking in the wrong direction (according to the symbol on the board and what I'm used to see elsewhere)?
But hey, there's your name on those, you made them I guess?
Even more admiration!
Ha ha! Well spotted on the diodes.
If you look even closer on the 5V supply to that board you'll notice the red wire is connected to 0V and the white wire to +5V. I had a slight 'moment' when laying out that PCB and misread the data sheet for the relays and so ended up transposing the coil connections. Easily fixed though by turning the diodes around and reversing the 5volt supply connections, and much cheaper than getting a new set of boards fabricated. But it does still bug me that it's not right. It also meant a little logic change in the microcontroller monitoring the input selection.
If you look even closer on the 5V supply to that board you'll notice the red wire is connected to 0V and the white wire to +5V. I had a slight 'moment' when laying out that PCB and misread the data sheet for the relays and so ended up transposing the coil connections. Easily fixed though by turning the diodes around and reversing the 5volt supply connections, and much cheaper than getting a new set of boards fabricated. But it does still bug me that it's not right. It also meant a little logic change in the microcontroller monitoring the input selection.
Alan, going by measurements alone, I think you've answered your own question. I would expect that most people can't hear the noise / distortion that you're measuring.
If you're motivated, push through the diminishing returns barrier and see whether you can hear an improvement. Assuming that the expectation bias doesn't feature, I'll bet you you won't notice..
Implementation of a switchable gain
Helo everyone,
I have finished the board for the BA2018 and power supply and find this preamp is really fantastic and enjoyable. But I need a little help as I go forward.
My intention is to have a selectable gain switch and I have a few questions about a proper implementation.
I plan to have 2 gain selections, one will be the stock 3.7 (or thereabouts) and the other one I would like to have as close to 1 as possible. I have built the preamp with the high output option and wonder how low can I make the gain and have it remain stable.
My implementation is to use a small relay, probably an NEC EA2-12NJ, configured between CN2(1) and CN2(2) on the schematic so that it switches between a direct connection or a resister (said resistor being in series with R17). Is this a reasonable way to implement this and will I run into any problems over the long term if I do this.
Thanks in advance for our advice and guidance. This has all been a great learning experience.
Helo everyone,
I have finished the board for the BA2018 and power supply and find this preamp is really fantastic and enjoyable. But I need a little help as I go forward.
My intention is to have a selectable gain switch and I have a few questions about a proper implementation.
I plan to have 2 gain selections, one will be the stock 3.7 (or thereabouts) and the other one I would like to have as close to 1 as possible. I have built the preamp with the high output option and wonder how low can I make the gain and have it remain stable.
My implementation is to use a small relay, probably an NEC EA2-12NJ, configured between CN2(1) and CN2(2) on the schematic so that it switches between a direct connection or a resister (said resistor being in series with R17). Is this a reasonable way to implement this and will I run into any problems over the long term if I do this.
Thanks in advance for our advice and guidance. This has all been a great learning experience.
Starting my build and looking for a best practice in regard to tapping off some power to feed the Mesmerize input selector. PS is the VRDN. The Mesmerize has option to be powered by either AC or DC, so the question is whether the best practice for this would be to tap AC off of the transformer or tap DC off the VRDN output. Goal is to not introduce any adverse affect to the linestage DC in. Assume that the transformer is adequately sized. Thoughts? Six of one, half dozen of another or is there a best practice?
Stroob
Stroob
Another BA2018
Hi all,
after finishing my F3 I wanted to gear up the frontend as well.
After challenging the SMD-stuff (SMD? There's a reason I normally prefer tubes ...) the rest was easy going.
My modular pre-amp (WIP since 1997) lost his tube line-stage and the BA2018 went in. PSU +/- 18V with active hum-compensation. See pictures of scope before/after below. Added some copper on the outputs, even if not necessary.
Measures very good, THD 0,007% 1,41V Output 10-30kHz. The pre has a high accuracy relay volume control and a tube-filter (on the right upper corner in the capacitor-box
) as well as a passive source selector.
Sound is very relaxed and detailed with deep soundstage, first time almost no difference with or without tube-filter. Like it!
Hi all,
after finishing my F3 I wanted to gear up the frontend as well.
After challenging the SMD-stuff (SMD? There's a reason I normally prefer tubes ...) the rest was easy going.
My modular pre-amp (WIP since 1997) lost his tube line-stage and the BA2018 went in. PSU +/- 18V with active hum-compensation. See pictures of scope before/after below. Added some copper on the outputs, even if not necessary.
Measures very good, THD 0,007% 1,41V Output 10-30kHz. The pre has a high accuracy relay volume control and a tube-filter (on the right upper corner in the capacitor-box
) as well as a passive source selector.Sound is very relaxed and detailed with deep soundstage, first time almost no difference with or without tube-filter. Like it!
Attachments
Perhaps wrong translation, and as this is not my idea, just let me post the link to the article my PSU is based on:
Spannungsregelung, elektronischer Brummsiebung (Komplementär-Darlington, low-noise)
Have built it for my MC and MM RIAA-stages with very good results before.
Spannungsregelung, elektronischer Brummsiebung (Komplementär-Darlington, low-noise)
Have built it for my MC and MM RIAA-stages with very good results before.
Well, I powered up my pre and when I checked the voltage at the board, I had 36 volts at the board.
I know I should have checked it prior to connecting it to the board and even questioned weather that was correct or not after seeing and checking voltages from the store PSU in my prior builds.
My question is , did I fry anything on the main line stage board.
F$&%
I know I should have checked it prior to connecting it to the board and even questioned weather that was correct or not after seeing and checking voltages from the store PSU in my prior builds.
My question is , did I fry anything on the main line stage board.
F$&%
