Wayne's BA 2018 linestage

6L6

6L6

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In a sealed relay, it doesn’t matter much, the corrosion/oxidation is contained.

When dealing with signal and using a toggle switch, gold is highly recommended for corrosion resistance, as there isn’t enough current to clean the contacts, a happens in larger-signal applications.
 
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6L6

6L6

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The resistors are all 1/4w or better supplied in the kits. Yes, even the teeny ones. Those are Vishay MBA and are 400mW rated, even though the bodies are itsy-bitsy.

Of course, do the math yourself if you are using smaller and are worried, but 1/4w works just fine.
 
bhjazz

bhjazz

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Joined 2006
Thanks! I will probably socket R16 and R17 (for later experimentation) and had a mix of replacements for them here, so thought I would ask.
 
bhjazz

bhjazz

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Joined 2006
I'm getting to the end of my parts procurement and thinking about fusing my BA2018. The plan is to use an Antek AS-0518 50VA transformer to power 3 VRDN boards: 1 for each BA2018 channel and 1 for a Muses/MCL kit. Looking at calculations posted elsewhere in this thread, it looks like 50VA/120V = 416mA.

Should I opt for a 0.5A fuse or a 1A fuse? I feel as if the 1A might do better dealing with turn-on peaks but I don't want to wander too far off.
 
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andynor

andynor

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Joined 2020
Yes, do not double. Start with the lowest and use a bigger fuse if the low one blows. You need it to blow if an error occurs. 500mA slow blow sounds about right, if your calculation holds true. Just order a few values and test.
 
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Sancho49

Sancho49

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Joined 2013
Hi,
I've finish the build of the BA2018 LineStage.
Everything is Ok but i've a small oscillation on the outputs ...
_Capture 1 : Signal 1Khz / 2V PP / Volume pot @ MAX / Wavy curve ..... (Do you think it's normal ?)
Cap1.png


_Capture 2 : No signal / Volume pot @ MAX / 10mV/div
Cap3.png


Cap2.png
_BA2018 LineStage :

  • IEC EMI Filter
  • Talema toroidal transformer 50VA 2x18V
  • Regulated Linear Power Supply Module Dual LME49710 / MJE15032 - +/-18VDC Output
  • 100K Sterero stepped attenuator

Ext1.jpg

Ext2.jpg


Thank you again Mr Wayne Colburn & Community !
 
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M

margol

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Joined 2005
What was the load during the measurements?

Was the input shorted for no-signal measurements?

Can you make a fft spectrum of these signals?

Have you checked the output voltage from the regulators on the oscilloscope?

If you turn off the linestage does the oscillation disappear?
 
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andynor

andynor

Member
Joined 2020
Sancho49 said:
Hi,
I've finish the build of the BA2018 LineStage.
Everything is Ok but i've a small oscillation on the outputs ...
_Capture 1 : Signal 1Khz / 2V PP / Volume pot @ MAX / Wavy curve ..... (Do you think it's normal ?)
View attachment 1280230

_Capture 2 : No signal / Volume pot @ MAX / 10mV/div
View attachment 1280233

View attachment 1280232 _BA2018 LineStage :

  • IEC EMI Filter
  • Talema toroidal transformer 50VA 2x18V
  • Regulated Linear Power Supply Module Dual LME49710 / MJE15032 - +/-18VDC Output
  • 100K Sterero stepped attenuator

View attachment 1280234
View attachment 1280235

Thank you again Mr Wayne Colburn & Community !
Click to expand...
Looks perfectly fine. Short your inputs, max your pot, then make new measurements without signal. Since it also seems to sound fine, no reason to worry.

If still an issue, post exact circuit you used with all values, and tell us what you possibly changed from the original.
 
RainfallSky

RainfallSky

Member
Joined 2015
Sancho49 said:
Hi,
I've finish the build of the BA2018 LineStage.
Everything is Ok but i've a small oscillation on the outputs ...
Click to expand...
Might not be relevant but I see you have one PSU and a WLS board where ground planes for L an R channels is not connected together. At least on the board.
 
chirs

chirs

Member
Joined 2010
I'm looking to build a preamp and I'm wondering if this linestage is the best way to approach it.
I have a few DIY audio projects under the belt now, the Starving Student II probably being the most involved.

I'm trying to understand what it takes to bring this into reality as a fully-fleshed preamp, chassis and all.
For context, I'm looking to have, at minimum, 2 or 3 inputs (unbalanced), a volume controller, a power switch and a nice metal chassis.
Nice to haves:
  • remote control volume & power
  • tone controls
From what I understand, the following all need to come together somehow:
  • the linestage
  • a volume pot breakout board
  • a PSU (lot's of questions here .. these seems daunting!)
  • any "nice to have" modules

And then of course, how do know how to hook all these things up together? It certainly isn't plug n' play :)

Thanks for taking the time to help a total newbie!
 
6L6

6L6

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Well, a good place to start to understand the overall connections and such is Rod Elliott’s P88

https://sound-au.com/project88.htm

And basically you could use the BA2018 as the active part.

As for other functionality, choose or omit as you like.

Regardless, looking at P88 is a good resource in general.
 
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rolandong

rolandong

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Joined 2004
I would do it progressively.
Start with BA2018 as offered in diyaudio store.
Once its working and you like it,
then add features as you deem important to you.
 
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bhjazz

bhjazz

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Joined 2006
My Antek AS-0518 transformer has 22 ga wire on the primaries and 20 ga on the secondaries. I will be connecting it to three VRDN boards. Would it be worth it to use 18 ga wire or should I just stay with 20ga?
 
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