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kevin gilmore

current feedback electrostatic amp

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14 minutes ago, vivolo said:

Does anyone have any extra Blue Hawaii PSU boards that they would be willing to sell me? 

I prefer to build a BH PSU as it is cheaper than a GRHV, and I am trying to make this more of a "bugdet" amplifier build.

Did you want the Blue Hawaii Ultra mini?  I believe I have one set of Electorstatic CFA boards and a BH Ultra Mini PS board.

Edited by sbelyo

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Finally cased my ES CFA amp. 

Returned the bias resistors to 1M with the larger heatsinks. Running 20mA bias for the output sections.

ES CFA 1.JPG

ES CFA 2.JPG

ES CFA 3.JPG

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On 8/26/2019 at 12:16 AM, mwl168 said:

Finally cased my ES CFA amp. 

Returned the bias resistors to 1M with the larger heatsinks. Running 20mA bias for the output section.

It was quite hot in this size with that current of my build. Is your amp running hot too?

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8 hours ago, joehpj said:

It was quite hot in this size with that current of my build. Is your amp running hot too?

Where I live, the ambient temperature at this time (end of August) is around 70 F, about 22 Celsius. The heatsink temperature of the amp gets to about 45C fully warmed-up.

When I first cased the amp, the ambient temperature was around 27 Celsius and the heatsink was ~ 48C not quite 50.

I can see the heatsink hit high 50's C in Taiwan where the ambient temperature can easily hit low to mid 30's C this time of the year.

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Stax DIY newbie here. Great looking amp @mwl168

 A couple of questions if I may:

1. This is probably a stupid question, but how do you adjust the volume on this amp? 🙂

2. What are the width and depth of this chassis? Is the front plate available also in black? 

3. Roughly how much did this cost?

 

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1. I use the digital volume on my DAC but you can easily add a volume control to the amp.

2. This chassis I use is quite small - dimension is 160mm x 70mm x 311mm. It's only for the amp circuits and you cannot fit the entire amp in it. There is a PSU in a separate chassis. As an example, you should be able to fit the entire amp including the PSU in a chassis like this

3. My rough estimate for parts alone would be about $700 US that also covers chassis, transformer, connectors, wires and a reasonable 4-gang volume pot. Like most things these days, labor is the biggest investment.  Cost can escalate quickly if you start getting into fancy chassis, volume pot and boutique parts (resistors, capacitors, wires, etc.).

Edited by mwl168
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Thanks! I would use this together with ADI-2 DAC which has quite configurable line out volume options, so I guess I could easily live without a volume knob as well. Now I will look if there is a thread about voluntary builders, for a fee of course. I also sent out a question to my facebook network if there are any electronics builders out there. I decided that optimally I would like to build one myself with somebody who knows what he is doing. Starting with this, completely solo, is probably not a good idea. 🙂

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