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Group buy pulse check for Pete Millett tube crossover PCB

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#25
Hello leadbelly,

I have downloaded the file package from Pete Millett's site and also downloaded Eagle CAD 5.4.0 but the file extentions on the Millett files do not seem to be what Eagle is looking for. Can you offer any suggestions so I can open the board files and study the board layout.

Thanks, leadfinger
 
#27
Just got a picture of our completed boards from the mfg. Boards are on their way.
 

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#28
the Millett files do not seem to be what Eagle is looking for. Can you offer any suggestions ...... No, sorry, I can't, I am very PCB-software-illiterate. Anybody else?
Click to expand...

I use Eagle for all of my boards. The archive on Milletts page does not contain any Eagle files. The only files present are the Gerber files needed to fab the board. They can be viewed with a Gerber viewer like Viewmate. There is no schematic, board files, or placement diagram.
 
#30
Oops, missed the group buy. I guess this is what I get for not checking the forum for a month. Can these be ordered directly from Pete or someone else (for a higher price obviously)? I did not see a link for PCBs on Pete's pages so I'm assuming I can't. If there is one extra, please let me know.

thanks,

Dave
 
#31
tubelab.com said:


I use Eagle for all of my boards. The archive on Milletts page does not contain any Eagle files. The only files present are the Gerber files needed to fab the board. They can be viewed with a Gerber viewer like Viewmate. There is no schematic, board files, or placement diagram.
Click to expand...

I've updated the .ZIP file to include the Eagle SCH and BRD files. Very strange, they were present in the web image on my hard drive, but not on the server. Seems that FrontPage doesn't always recognize certain files being updated, so I have to manually delete them from the server and re-publish. I had the same issue with some PDF files.

I also added a primative BOM - basically just what Eagle kicks out. That's all I have. This is a pretty old project...

Pete
 
#34
My capacitor contribution

My favorite capacitor type, for the signal path, is polystyrene. Because of environmental regulations :yuck: , polystyrene has been phased out and sonically inferior materials have become the norm.

I want to use 0.001uF polystyrene in the xover and because you use 12 per channel, I began looking for a reasonably priced supply.

My favorite distributer, Mouser, has a 0.001uF 500v polystyrene radial capacitor available for $0.33 or less ($0.16 in qty of 100).

They are not available in the catalog or through a regular search. The Mouser PN is 53PW210K

Enjoy.
 
#35
Seems that FrontPage doesn't always recognize certain files being updated, so I have to manually delete them from the server and re-publish. I had the same issue with some PDF files.
Click to expand...

I have had similar issues. Sometimes you update a file, especially a PDF, then upload to the server. You think everything is fine, because the pages that you changed look fine, but the PDF's never changed.

I have tried to change over to Expression Web, but it wants me to do every page over, so I am still using FP.
 
#36
initial observations

I could not wait for the PCB so I put together 2 channels of low pass. Some initial observations:
1. The x-over inverts phase
2. The gain is -15db
3. I was shooting for 600Hz LP. With closely matched parts the -3db point is 700Hz. This means the x-over point (-6db)is way off.
 
#39
Re: initial observations

audio_builder said:
I could not wait for the PCB so I put together 2 channels of low pass. Some initial observations:
1. The x-over inverts phase
2. The gain is -15db
3. I was shooting for 600Hz LP. With closely matched parts the -3db point is 700Hz. This means the x-over point (-6db)is way off.
Click to expand...

1. It's a VCVS based implementation, VCVS don't invert phase, (in band that is) however they do have some delay.

2. Something wrong here, as gain in band should be relatively close to unity figuring each stage has a gain of >0.9 inside the passband. I would expect something like -1dB to -1.5dB in band.

3. Gains of much less than expected will affect the transfer function of the filter and the X-O point will not be in the expected place nor of the expected magnitude.

I have built very similar X-O in the past and once you compensate for the fact that less than unity gain is available in the filter blocks you can get very reasonable approximations of any moderate Q transfer functions that can be realized at near unity gain.

What supply voltages are you using, and what is the load impedance you are driving? What are the values of the caps and resistors used in your filter, and are the resulting filter network impedances relatively high compared to the source impedance of the stages driving them?
 
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