By any chance, did someone built the stereo BA 2018 with volume pot and balance pot, if yes could you post the schematic, thanks
Selector, Volume and Balance All come before the input to the PCB. Look to the following articles for general layout -
High Quality Audio Preamp
Potentiometers (Beginners' Guide to Pots)
High Quality Audio Preamp
Potentiometers (Beginners' Guide to Pots)
Dumb question:
I am looking to buy the PCB and parts kit at the diyaudio store for a stereo line stage. Just to confirm, I just need to buy one PCB and two parts kits and also the parts kits have every part I need, including proper grades of semiconductors. I asked the folks at the store and was directed here.
Appreciate your feedback in advance.
I am looking to buy the PCB and parts kit at the diyaudio store for a stereo line stage. Just to confirm, I just need to buy one PCB and two parts kits and also the parts kits have every part I need, including proper grades of semiconductors. I asked the folks at the store and was directed here.
Appreciate your feedback in advance.
No such thing as a dumb question. 😀
One parts kit will stuff one board. You still need PSU, selector, volume, jacks, etc...
I.E., buy the PCB and the parts kit and you have this -
One parts kit will stuff one board. You still need PSU, selector, volume, jacks, etc...
I.E., buy the PCB and the parts kit and you have this -
Thanks 6L6!
Are the semiconductors in the parts kit the right grade and do they need further matching?
Are the semiconductors in the parts kit the right grade and do they need further matching?
No matching required. Parts included to use big or little outputs, and an extra Jfet or two in case you sneeze...
6L6 and all...
Mentioning volume catched my attention—I was wondering wether an AVC would be fine with this board?
I‘m coming along fine with the build and think hard about what volume control to use...
(And it was mentioned that using some output-transformer (lost the proper term for it—plus 6dB feeding F4 is the catch-phrase here...)
Mentioning volume catched my attention—I was wondering wether an AVC would be fine with this board?
I‘m coming along fine with the build and think hard about what volume control to use...
(And it was mentioned that using some output-transformer (lost the proper term for it—plus 6dB feeding F4 is the catch-phrase here...)
Sure, use the AVC, that would be intriguing, I suspect it would be great!!
You can use a 1:1 quadfilar transformer wired as autoformer, or a transformer with a gain ratio, or you could just change the gain in the BA2018. Gain is 1+R16/R17.
+6db would bring gain from 3.7x to 7.4x, try R17 2.7K, R16 20K. This would decrease feedback and subsequently increase distortion a little, but it's worth a try since this circuit is so clean to begin with.
You can use a 1:1 quadfilar transformer wired as autoformer, or a transformer with a gain ratio, or you could just change the gain in the BA2018. Gain is 1+R16/R17.
+6db would bring gain from 3.7x to 7.4x, try R17 2.7K, R16 20K. This would decrease feedback and subsequently increase distortion a little, but it's worth a try since this circuit is so clean to begin with.
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Is there any reason not to use the larger output devices, even if not (immediately) including a headphone output? Or are the smaller output devices preferable if not using a headphone jack? I wasn't originally planning to include a headphone jack but might in the future, so I'm weighing options.
I'm using 2x VRDNs at 18V, each with a 15VA transformer if that matters.
I'll delete this question if I find the answer before someone answers...
I'm using 2x VRDNs at 18V, each with a 15VA transformer if that matters.
I'll delete this question if I find the answer before someone answers...
I am having a really tough time reading the small blue caps that came in the parts kit. I believe one pair are 10pF and the other 5pF. There are two with longer leads on a tape roll, and two with short leads loose in the bag.
My multimeter is pretty ok at measuring capacitance but was scratching its head with these. And under powerful magnification and strong lighting I can't read the text. I've even been poking around on Mouser to try and find these but no luck so far.
My multimeter is pretty ok at measuring capacitance but was scratching its head with these. And under powerful magnification and strong lighting I can't read the text. I've even been poking around on Mouser to try and find these but no luck so far.
Fired up the balanced BA 2018 boards today after testing all four with the VRDN power supply....I connected the positive input phase to one channel in on the BA18 board, whilst linking -in to ground, and then the output of that board to + on the output socket The - in I connected to input + on the second board, also bridging ground to - input, with the output of that board connected to - on the output socket...the good news is that it works and produces no hum that exceeds my tinnitus threshold, plus plenty of volume. No bad news as such but a feeling that the grounding system is kinda complicated and wondering how anybody else has done this ?
On another note, I took AVdesigngurus advice on another thread and bought a laser thermometer to check heatsink temp on the VRDN power supply, as they have been chopped down to fit in a 1U chassis...so far not much movement above room temp but the heatsink on the M2X amp gets up to 55 degrees Centigrade.
Hot yes, too hot ??
On another note, I took AVdesigngurus advice on another thread and bought a laser thermometer to check heatsink temp on the VRDN power supply, as they have been chopped down to fit in a 1U chassis...so far not much movement above room temp but the heatsink on the M2X amp gets up to 55 degrees Centigrade.
Hot yes, too hot ??
All my very small blob caps were loose in the bag. I assumed the smaller pair was the 5, and the slightly larger pair was the 10. Hopefully that's right. I have an old Fluke with a cap measure, but not down in this tiny pf range.
Mine is just a finished board right now, didnt want to "undo" my working version with the old original 2 board set, its working very well. I have volume pot, selector switch and board (I-Select) stuffed and ready.
I do still need parts for VRDN power supply and a transformer....as well as another chassis.
Russellc
I had similar experiences concerning parts/values (hence my questions a bit back in the thread)
The .1 and .05 are really hard to read/distinguish...
Maybe, in a next batch, the parts for the variation could be set apart (in a bag in the bag, or just sticked together with a tape or whatever) just to indicate there’s more than just a kit?
Minor issue if the builder (like, me) takes the time to inspect what exactly is in the bag...
Have to finish my vrdn, hook it all up and see how good exactly it is [emoji2956] (may need advice next week on wiring up the toroidal as I fear I overshot...)
The .1 and .05 are really hard to read/distinguish...
Maybe, in a next batch, the parts for the variation could be set apart (in a bag in the bag, or just sticked together with a tape or whatever) just to indicate there’s more than just a kit?
Minor issue if the builder (like, me) takes the time to inspect what exactly is in the bag...
Have to finish my vrdn, hook it all up and see how good exactly it is [emoji2956] (may need advice next week on wiring up the toroidal as I fear I overshot...)
I agree about the parts bag labeling. This was my first build without a guide or clear photos (thanks 6L6 for your F5 guide!). I figured it would be fairly clear what to do but since the package from the store contained no info I didn't even know about the alternate parts until recently.
I still don't know a lot about then other than the alternate parts can be used to drive headphones. But is there a reason to build the original configuration? Is it marginally better as a preamp if you're not going to use headphones?
I still don't know a lot about then other than the alternate parts can be used to drive headphones. But is there a reason to build the original configuration? Is it marginally better as a preamp if you're not going to use headphones?
Yes, it did have the schematic that explained what parts to swap or omit. But it doesn't explain the pros/cons of the alternative parts other than being able to support headphones. But I'm guessing the originals are preferred if headphones won't be used? Otherwise the kit would have just evolved to use the alternate parts for all use cases(?). That, and the confusion about the blue caps, are the things I stumbled over and had a hard time finding clarification.