william2001
I have a BA2018 with Super Regulator power supply. Works fine. Very quiet. Dumb question about your BA2018 boards. Do you have the -IN terminals jumpered to the G terminals on the input blocks? The original schematic did not include the text that tells you to do that for unbalanced input configuration.
I have a BA2018 with Super Regulator power supply. Works fine. Very quiet. Dumb question about your BA2018 boards. Do you have the -IN terminals jumpered to the G terminals on the input blocks? The original schematic did not include the text that tells you to do that for unbalanced input configuration.
Do you have a picture of your preamp? Mine is identical to the schematic in post #1. Original purple boards, R17 grounded like this picture. https://www.diyaudio.com/forums/attachment.php?attachmentid=728494&d=1547319939
I have the blue dual-mono DIY store board. I did not realize the original purple boards were different.
https://diyaudiostore.com/collections/pre-amplifier/products/waynes-ba18-pre-amp
https://diyaudiostore.com/collections/pre-amplifier/products/waynes-ba18-pre-amp
Well I kinda meant pictures of your finished project, showing how you have the wiring arranged / raw DC supply / grounds / etc. in this "known good" configuration. There does not seem to be many pictures of these in the wild that I can study, or at least I'm having trouble finding them.
william2001
I've built three BA2018s and had forgotten that the one with a SRPS was built with a dual-mono, split-able BA board I got from forum member IckyB. Also, the SRPS board is a layout I did myself, taken from schematic V2.3 with an added on-board transformer, rectifier/filtering circuit and power LED connection. So the attached photo may not be much help. It's also possibly the densest chassis build I have done.
For what it is worth, the SRPS ICs (just barely visible at the far left) are AD825 and there is a 0.01uF bypass cap connected between the SRPS ground and chassis ground. Ref voltage is 6.9V and R15/25 (R6/13 on V2.3 schematic) is 1.5K ohms, providing around +/-18V at the regulator outputs.
The IckyB board (not split into 2 pcs) has power connections on the outside edges and also in the middle where the two circuits are divided by the score line. I connected DC power to both channel edges on separate home runs and the sense wires to the board middle and jumpered across the split line. All the power and sense home runs are twisted pairs.
Schematic and parts list for my V1.0 SRPS is attached for reference. The IckyB boards follow Wayne's schematic but not his layout.
I've built three BA2018s and had forgotten that the one with a SRPS was built with a dual-mono, split-able BA board I got from forum member IckyB. Also, the SRPS board is a layout I did myself, taken from schematic V2.3 with an added on-board transformer, rectifier/filtering circuit and power LED connection. So the attached photo may not be much help. It's also possibly the densest chassis build I have done.
For what it is worth, the SRPS ICs (just barely visible at the far left) are AD825 and there is a 0.01uF bypass cap connected between the SRPS ground and chassis ground. Ref voltage is 6.9V and R15/25 (R6/13 on V2.3 schematic) is 1.5K ohms, providing around +/-18V at the regulator outputs.
The IckyB board (not split into 2 pcs) has power connections on the outside edges and also in the middle where the two circuits are divided by the score line. I connected DC power to both channel edges on separate home runs and the sense wires to the board middle and jumpered across the split line. All the power and sense home runs are twisted pairs.
Schematic and parts list for my V1.0 SRPS is attached for reference. The IckyB boards follow Wayne's schematic but not his layout.
Attachments
Thank you avdesignguru. Haven't taken my preamp apart yet. Just been thinking and lining up some ideas to try. Your picture and info gives me another data point..
Haven't gone through all 157pp so apologize if this is covered above somewhere, but...
Just finished my firs WB 2018 linestage and it is superb. Want to build another and the parts are now unavailable on DIY. So checked post 508 above, got the BoM and all is available except for the bipolar transistor KSA1220AYS. This part has been discontinued by onsemi.
Are their other equivalents? Other sources? (DigiKey is out as well and will not be stocking in the future).
Thanks, folks. My build houses both the WB 2018 togather with the Korg B1 and allows you to switch easily between the two -- with PSUs from Gareth at AudioSy.net. Very enlightening to compare these two pres and the nature of tube versus SS in general.
Just finished my firs WB 2018 linestage and it is superb. Want to build another and the parts are now unavailable on DIY. So checked post 508 above, got the BoM and all is available except for the bipolar transistor KSA1220AYS. This part has been discontinued by onsemi.
Are their other equivalents? Other sources? (DigiKey is out as well and will not be stocking in the future).
Thanks, folks. My build houses both the WB 2018 togather with the Korg B1 and allows you to switch easily between the two -- with PSUs from Gareth at AudioSy.net. Very enlightening to compare these two pres and the nature of tube versus SS in general.
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Instead of the KSA1220 / KSC2690, you can use Toshiba TTA004B and TTC004B. Direct replacement; that's what I used; works very well. 🙂
Mouser is well-stocked on the TTAs, and has some TTCs - many more of those in 4 weeks.
Also, there are generic substitutes for the KSA1220, like 2SA1220 from Inchange Semiconductor.
Hope this helps, regards, Claas
Mouser is well-stocked on the TTAs, and has some TTCs - many more of those in 4 weeks.
Also, there are generic substitutes for the KSA1220, like 2SA1220 from Inchange Semiconductor.
Hope this helps, regards, Claas
It does Claas and thanks. 6L6 has already offered some spares and I cannot thank him enough. Looks like to will be easy to get a second board and running -- if I can negotiate another round with the SMDs, that is. Those are one tiny pieces, aren't they?
Oh yeah, that was an adventure ... first time I worked with a headband loupe. But I managed to solder them with my usual soldering iron, using a very fine tip and very fine solder 😒
Regards, Claas
Regards, Claas
What should the source resistors be if im using j309? I spun a to92 version of this circuit, put j309 s in it with the source resistors x10 the stock value (10ohm>100ohm, 33ohm>330ohm) and it works fine but sounds shrill. Everything else is as per the schematic.
Should i have changed something else and not the source resistors?
Should i have changed something else and not the source resistors?
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I figured it out. Its just r3 r4 that needs to be higher of which i settled on 200ohm. I still find the version with the j309 inferior to 2sk209. The treble is less refined. I guess its the limitation of the component?
Well i tweaked the new board with the j309s to have exact same components as the 209 board and now i really cant tell them apart soundwise. In that regard the through hole version is a success. Now looking for ways to improve the schematic itself of this wonderful circuit. Ideas welcome 🙂
Wayne wrote early on that "To make this balanced to SE lift the gound of R17 and feed in the - signal and change R20 to 10K. R18 to 27K."
if I make this change, can I still input an SE signal? I have 4 inputs, only one of which is an XLR (mostly for convenience as I have a balanced source and balanced power amp and I am replacing a balanced preamp and want to keep using my existing cables)
does “lift the ground of R17" simply mean taking the ground signal for the XLR from one end of R17 or is that a term that i‘m not familiar with.
Apologies for the questions. English is my first language but I’m an idiot.
if I make this change, can I still input an SE signal? I have 4 inputs, only one of which is an XLR (mostly for convenience as I have a balanced source and balanced power amp and I am replacing a balanced preamp and want to keep using my existing cables)
does “lift the ground of R17" simply mean taking the ground signal for the XLR from one end of R17 or is that a term that i‘m not familiar with.
Apologies for the questions. English is my first language but I’m an idiot.
Never mind. I’ve realised the above will not work as I was picturing it.
I think some of this stuff is finally starting to sink in 🙂
I think some of this stuff is finally starting to sink in 🙂
To anyone who has built the BA-3 Preamp, what are your listening impressions versus the BA2018? I am loving mine so far but am always curious about future projects.