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Wayne's BA 2018 linestage
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Old 17th September 2021, 05:18 PM   #2881
jimk04 is offline jimk04  United Kingdom
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I have a Chinese Quicko T70 or something. It heats up super quickly and has a sleep setting. With my asbestos fingers I can almost hot swap tips!
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Old 18th September 2021, 03:20 PM   #2882
turion64 is offline turion64  United States
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Wayne's BA 2018 linestage
Quote:
Originally Posted by jimk04 View Post
I have a Chinese Quicko T70 or something. It heats up super quickly and has a sleep setting. With my asbestos fingers I can almost hot swap tips!
If it works, it works…

Probably have no fingerprints left..hahahahahaha

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Old 27th September 2021, 01:42 AM   #2883
luvrockin is online now luvrockin  United States
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Wayne's BA 2018 linestage
Hello gang, many months ago I started Wayne’s BA2018. I got super busy with work over the summer so it sat until recently I was able to complete it. I’ve included some pictures of the completed work. It sounds great sonically BUT I have a noise issue. I have a buzzing sound coming out of both speakers going through my F5T amp. I’m going to start digging into it tomorrow and I’ll also try it on a commercial amp I have to see if the problem is there as well. I was hoping to get some help with the grounding. I want real sure what to do with the shields since I connected the Linestage for SE input and not balanced. Thank you in advance
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Old 27th September 2021, 02:33 AM   #2884
6L6 is offline 6L6  United States
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Wayne's BA 2018 linestage
This is RCA in to RCA out, yes? It looks like you have the input wired incorrectly... Red to (+IN), white to (GND), jumper (-IN) to (GND).

You can attach the shields to GND as well.

A couple of questions -

Where does PSU ground (not safety earth) connect to chassis?

What's the circuit on perfboard?

What is the function of the gold capacitors (and a resistor...?) haphazardly jammed into the BA2018 PCB?
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Old 27th September 2021, 10:21 AM   #2885
andynor is offline andynor  Norway
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Quote:
Originally Posted by luvrockin View Post
Hello gang, many months ago I started Wayne’s BA2018. I got super busy with work over the summer so it sat until recently I was able to complete it. I’ve included some pictures of the completed work. It sounds great sonically BUT I have a noise issue. I have a buzzing sound coming out of both speakers going through my F5T amp. I’m going to start digging into it tomorrow and I’ll also try it on a commercial amp I have to see if the problem is there as well. I was hoping to get some help with the grounding. I want real sure what to do with the shields since I connected the Linestage for SE input and not balanced. Thank you in advance
Second 6L6s comments.

Just a thought: did you test the circuit alone, and was it quiet then? Meaning nothing else attached but power? The Muse-circuit kinda complicates troubleshooting. So a thought would be to disconnect it, short your inputs (+ and - shorted to gnd, ref 6L6s handwritten schematic earlier in the thread, and if quiet then, connect more stuff and see when the noise kicks in.

Also, the question of gnd is relevant. Looks like your chassis and PSU gnd is directly connected together. I also see the muse board is connectd to gnd. Again, disconnecting these things and simpifying before troubleshooting, may be an idea.

I recommend a look at 6L6s Pearl 2 guide for gnd inspiration, very good stuff.
Regards,
Andy
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Old 27th September 2021, 12:32 PM   #2886
myleftear is offline myleftear  Switzerland
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Or, as a variant to andy‘s way, just disconnect the muses, and hook up something with an attenuator ( phone, laptop etc) directly to the WLS‘s input.

Muses is said to require a separate psu especially for the display … if the pre is quiet without the muses, you could reconnect it, but without display (if thats possible), and hear what that gives…
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Last edited by myleftear; 27th September 2021 at 12:34 PM.
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Old 27th September 2021, 12:59 PM   #2887
luvrockin is online now luvrockin  United States
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Quote:
Originally Posted by 6L6 View Post
This is RCA in to RCA out, yes? It looks like you have the input wired incorrectly... Red to (+IN), white to (GND), jumper (-IN) to (GND).

You can attach the shields to GND as well.

A couple of questions -

Where does PSU ground (not safety earth) connect to chassis?

What's the circuit on perfboard?

What is the function of the gold capacitors (and a resistor...?) haphazardly jammed into the BA2018 PCB?
6L6, Thank you for the input. I totally forgot about jumping the in- to ground and I did that. I still have the noise.

The PSU is grounded at the chassis ground. From the power inlet, the green goes to the chassis and the another green wire comes from there back to the ground terminal block on the PSU board.

The circuit in the perf board is a muting relay circuit. It’s shown on the Academy Audio webpage in the schematic for the BA2018.

The gold caps and resistors on the BA2018 is another mod on the Academy Audio website. It’s and RC filter. This is how they describe it on their page

Referring to Figure 3 below, note extra components added to the positive and negative power rails of each BA2018 board. Referring to the Left channel, the RC filter R101 C14 on the V+ rail, and the R103 C15 on the V- rail improve transient response of the line stage and increase channel separation. Some of the available PCBs for 2018 may already have these components installed. There is no need to duplicate them. I didn’t recognize these on the schematic so I added them at this point.

Last edited by luvrockin; 27th September 2021 at 01:04 PM.
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Old 27th September 2021, 01:17 PM   #2888
luvrockin is online now luvrockin  United States
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Wayne's BA 2018 linestage
Quote:
Originally Posted by andynor View Post
Second 6L6s comments.

Just a thought: did you test the circuit alone, and was it quiet then? Meaning nothing else attached but power? The Muse-circuit kinda complicates troubleshooting. So a thought would be to disconnect it, short your inputs (+ and - shorted to gnd, ref 6L6s handwritten schematic earlier in the thread, and if quiet then, connect more stuff and see when the noise kicks in.

Also, the question of gnd is relevant. Looks like your chassis and PSU gnd is directly connected together. I also see the muse board is connectd to gnd. Again, disconnecting these things and simpifying before troubleshooting, may be an idea.

I recommend a look at 6L6s Pearl 2 guide for gnd inspiration, very good stuff.
Regards,
Andy

Andynor, thank you as well. As you suggested, i removed the input from the Muses to the BA2018 and it’s totally quiet on both channels. The power supply ground and power ground are connected together at the chassis. The muses MCU requires a +/-/g psu. I ran everything back to the psu for this. As for simplifying, I reconnected the inputs as normal but removed the +15v power lead to the muting circuit and sure enough it’s quiet as can be. I’m thinking this where my troubles are. Depending what I find, it’s not a necessity and can be easily eliminated. I will working on this later today.
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Old 27th September 2021, 01:21 PM   #2889
luvrockin is online now luvrockin  United States
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Join Date: Jan 2017
Location: St. John IN
Wayne's BA 2018 linestage
Quote:
Originally Posted by myleftear View Post
Or, as a variant to andy‘s way, just disconnect the muses, and hook up something with an attenuator ( phone, laptop etc) directly to the WLS‘s input.

Muses is said to require a separate psu especially for the display … if the pre is quiet without the muses, you could reconnect it, but without display (if thats possible), and hear what that gives…
Myleftear, Thank you for input as well. Prior to removing the power to the muting board, I removed the display ribbon cable and still have the noise. I think I will try to incorporate a separate power supply for the Muses and display later as well.
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Old 27th September 2021, 01:32 PM   #2890
andynor is offline andynor  Norway
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Nice work, finding the source of the noise so quickly! Also means the rest of the circuit is fine, good work. Wrt the RC networks, I think you are good without. Smoothing caps were added to the boards current revision, and more is not always merrier, as 6L6 kinda points out.

Good luck with the rest! Can’t help you with digi-noise, other than suggest a separate PSU, wich others have done too and you yourself are allready considering.

Edit: You could also consider a ground loop breaker according to Pearl 2 / Waynes way, if you at a later date find the gnd scheme had room for improvement wrt noise (can also be in the higher frequencies).

Regards,
Andy
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Last edited by andynor; 27th September 2021 at 01:37 PM.
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