Jump to content

current feedback electrostatic amp


kevin gilmore
 Share

Recommended Posts

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
Link to comment
Share on other sites

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?

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

  • 2 weeks later...

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
  • Like 1
Link to comment
Share on other sites

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. ?

Link to comment
Share on other sites

  • 4 weeks later...
  • 1 year later...
On 10/9/2019 at 3:55 AM, vivolo said:

I have created a BOM for the Blue Hawaii ultramini Power supply. I still need to select the big caps and screw terminals.

Which PSU is this exactly? Can link to any schematics with details? Thanks

Link to comment
Share on other sites

BH Mini PSU        
           
Resistor   Mouser P/N      
100R 2 660-MF1/2CCT52R1000F / 273-100-RC      
1.2K 2 660-MF1/2CC1211F / 273-1.2K-RC      
330K 2 594-5093NW330K0J 3W L=20.5mm  
430K 2 594-5093NW430K0J 3W L=20.5mm  
4.7M 1 594-VR37000004704JR5 HV    
           
1M 1 72-T93YB-1M Trimpot    
           
Semiconductor          
IXCP10M90S 2 747-IXCP10M90S   *  
FQPF8N80C 2 512-FQPF8N80C   *  
LM7815 1 512-LM7815CT / 863-MC7815ACTG    *  
LM7915 1 512-LM7915CT / 863-MC7915ACTG    *  
           
Zener          
24V 2 78-BZX85B24      
100V 2 625-Z4KE100A-E3/73 / 78-BZX85B100-TAP     100V*2+150V*1=350V
150V 4 625-Z4KE150A-E3     100V*1+150V*2=400V
1N4007 2 625-1N4007GP-E3/73      
           
Capacitor          
0.1uF/1KV 2 505-MKS4.1/1000/10 P=15mm   80-PHE426PB6100JR06
220uF/500V 4 598-80LX221M500K452 D=30mm * KX
    80-ALC10A331CF450      
470uF/35V 4   P=5mm/D=10mm   FC KW
           
Other          
GBU610 2 621-GBU610 / 625-GBU8M-E3/51    *  
3N254 1 625-3N254-E4 / 625-2KBP10M-E4    *  
Heatsink Large 2 532-530002B02500G H=63.5mm *  
Heatsink Small 2 532-581202B25G H=50.8mm *  
  • Like 1
Link to comment
Share on other sites

Any non-obsolete replacement for the 3N254? Thanks! 

Adding to the above BOM:

image.png

Here the Mouser basket as well (which is missing the obsolete 3N254 bridge rectifier): 

https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=9472151902

I would also exchange the 220uF/500V cap with a Nichicon LGN2H221MELB45 as it is rated up to 105°C and even cheaper. 

Edited by starcat
Link to comment
Share on other sites

Question regarding the bridge rectifier 3N254 - both alternative parts 3N254-E4 and 2KBP10M-E4 seem to be unavailable as well. Anyone used successfully any other replacement? Thanks.

Edited by starcat
Link to comment
Share on other sites

How about 621-KBP201G (Mouser PN). Haven't tried it but same specs. These bridge rectifiers are common parts and shouldn't be a problem to replace. Also a Rectron MDA201G would be another one to look at. 2A 100V bridge rectifier in an appropriate case/footprint and pinout.

  • Like 2
Link to comment
Share on other sites

Thanks guys. I'll try the Rectron MDA201G. It looks pretty much identical to the 3N254, same pinout, size and specs. Only diff is the 3N254 is max rated at 60amp vs 50amp for the MDA210G. 

The 621-KBP201G doesn't seem to be available soon from Mouser. 

Just found, the VS-2KBP01 looks like a new direct replacement from Vishay.

Edited by starcat
Link to comment
Share on other sites

This looks like a very nice case for a dual chassis design for the static CFA3.

PSU chassis: mount the kgsshvpssicfetsinglenewrightsws and kgsshvpssicfetsinglenewleftsws GRHV boards on the sinks together with goldenreference6d GRLV in the middle/front and a transformer in the middle/back. Might be even room for two GRLV and two transformers for total symmetry. 

Amp chassis: two balanced CFA3 boards mounted on the sinks. Will be pretty empty in the middle. The internal hight of 73mm might get tight but probably enough to fit the 63.5mm wide balanced boards; or mount them horizontally with some L-brackets. What do you think?

I think I might go for it. 

Chassis dimensions in mm are: outside W360xD270xH86, inside W280xD255xH73

image.png

Or just use single chassis with both CFA3 boards mounted on the sinks and a kgbhultraminipsv4 board in the midfront and a transformer in the midback. 

Edited by starcat
Link to comment
Share on other sites

Hmm, you might be right Jose, but the fins of the small enclosure Michael used above doesn't look like being much more of actual real estate... Btw, which one is it exactly? 

This might fit in the two balanced boards, the BH mini PSU and a transformer in the back. Bit too high probably but for the sake of bigger sinks. 

Chassis dimensions in mm are: outside W320xD315xH120, inside W220xD300xH112

screenshot_90.jpg

  • Like 1
Link to comment
Share on other sites

  • 2 weeks later...
  • 2 weeks later...

Some progress here and waiting on the KSc2752 transistors... 

Will be ordering the transformer, thinking about 2x [email protected] secondaries for the BH Mini PSU in order to get out 400V for the CFAe boards. This is what @jose has chosen. @congo5 however used [email protected] and ended up with 399VDC using the same BH Mini PSU. Any thoughts after running those for a while? 

IMG_1469.JPG

IMG_1471.JPG

Edited by starcat
  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...