If you set trimpot to midpoint what is Vds of Q1?
Also measure bias current while trimpot is set at midpoint.
Will do! Probably tomorrow evening. I assume the voltage across the 3 watt resistors will give me a valid current reading.
Thanks,
Skip
If you set trimpot to midpoint what is Vds of Q1?
Also measure bias current while trimpot is set at midpoint.
Vds of Q1 is 5.3 VDC.
Current is .52 milliamps (almost nothing).
The voltage across Q2 plus that across Q1 is close to the rail, but I can't see how the current across the resistors could be that low (.0003 V across .575 Ohms).
I can't come up with a hypothesis with my limited knowledge here.
Thanks,
Skip
Replace bjt bipolar transistor with new one and retest.
While doing so, I destroyed one of the traces (too many changes there), so I've ordered a new board. I have extras for almost all the parts. Thanks for your help even if I (or at least the board) were beyond help.
Skip
Just out of curiosity, as I have never delved that deep into electronics, how low can the ESR be for C1?
I understand the Cornell cap in the kit has an esr of 130 mOhms at 120 hz and 100 mOhms at 20k hz.
Would it be safe or catastrophic to use a cap that has an esr of anywhere around 30 to 80 mOhms at 120hz?
Thank you for your time. I appreciate it!
I understand the Cornell cap in the kit has an esr of 130 mOhms at 120 hz and 100 mOhms at 20k hz.
Would it be safe or catastrophic to use a cap that has an esr of anywhere around 30 to 80 mOhms at 120hz?
Thank you for your time. I appreciate it!
Yes, Since I bought a pair last week. The only change is inclusion on the board of pads for R15, the 2.2k resistor that increases the current and improves the performance. 6L6's guide shows soldering the leads of that resistor to one of the transistors and another resistor. Adding pads to the board cleans up the appearance and makes it a little bit easier for first-time builders. Addition of the 2.2k, .4 watt resistor is the only change to the BOM.
Skip
Skip
I'm putting both ACA boards into one enclosure. Can I power both boards with one SMPS 24v @ 5 to 6 amps? Or should I build a linear PS for them. The enclosure has room for either set up. I have done some searching here on the linear ps. Seems a Antec 18v/200va is needed.
Just my , but I think that in the spirit of the original design goals, an SMPS would still be the way to go. My own ACA build was the DIYAUdio store full kit - dual monoblocks, which came with dual laptop supplies - but I've been quite happy with Meanwell supplies from Parts Express for a class D amp build.
This one might fit the bill? Mean Well MW NES-150-24 24 VDC 6.5A 150W Regulated Switching Power Supply
The price is sure hard to argue against
For those who want to sniff their nose at inexpensive SMPS, Tom Christiansen at Neurochrome uses them extensively, and I've heard one of his small LM3886DR builds - sounded perfectly fine to me.
This one might fit the bill? Mean Well MW NES-150-24 24 VDC 6.5A 150W Regulated Switching Power Supply
The price is sure hard to argue against
For those who want to sniff their nose at inexpensive SMPS, Tom Christiansen at Neurochrome uses them extensively, and I've heard one of his small LM3886DR builds - sounded perfectly fine to me.
I'm putting both ACA boards into one enclosure. Can I power both boards with one SMPS 24v @ 5 to 6 amps? Or should I build a linear PS for them. The enclosure has room for either set up. I have done some searching here on the linear ps. Seems a Antec 18v/200va is needed.
Yes you can, a single 19V 4.5A laptop brick can run both the channels and still top power...if its first time build as Pass says first focus on the amp than the supply...upgrade later
Just my , but I think that in the spirit of the original design goals, an SMPS would still be the way to go. My own ACA build was the DIYAUdio store full kit - dual monoblocks, which came with dual laptop supplies - but I've been quite happy with Meanwell supplies from Parts Express for a class D amp build.
This one might fit the bill? Mean Well MW NES-150-24 24 VDC 6.5A 150W Regulated Switching Power Supply
The price is sure hard to argue against
For those who want to sniff their nose at inexpensive SMPS, Tom Christiansen at Neurochrome uses them extensively, and I've heard one of his small LM3886DR builds - sounded perfectly fine to me.
The meanwell has two outputs. Are they the same voltage?
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