Slewmaster - CFA vs. VFA "Rumble"

It does seem that the measured results are on the high side, although being H3 dominant was expected.

The trouble with measuring distortion is that experimental errors tend to be all +ve, you can't average them out, and you have to work hard to minimize the THD as much as you can - I never had the chance to do this as I don't have the equipment. I would probably look to have a 'control' sample, a simple circuit that I could use to establish the baseline of my test set up that was closer to the wiring set-up of the amplifier than a simple loop.



Agree!

But drilling all them holes is a pain - worth to have plenty of drills on hand as they blunt easily and this results in rough edges on the metal.
Hi Bigun i will repeat this test tomorrow .
I can test another INP to compare.
Thanks for reply all guys.
 
Spooky foil.
 

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Hi Thimios,

Yes I read that when you posted it. I got very interested. I even made a UV LED panel. Problem is those Photo sensitive boards are very expensive. I already had several one sided copper clad boards so the toner transfer must makes more sense for me at this time.

The only reason I etched the Wolverine and Spooky today is that Jason is planning other IPS first for gerbers so this will give me something to work on while I wait. I probably should have waited on the Spooky. I think OS is planning an upgrade on it.

I didn't quite finish the Worverine today. I didn't quite have all the parts I needed in my parts bin so I had to place an order. I should be able to at least one board for each IPS next week.
 
... I probably should have waited on the Spooky. I think OS is planning an upgrade on it.
...

From my last communication on the subject with OS I wouldn't stress too much about the pending 'upgrade' to the Spooky Leach IPS. It sounds like it will be relatively minor, so I'm inclined to pick back up on the artwork for Spooky.

I have Symasui almost complete and the Spooky Leach is probably 3/4 complete. I've got some very ill family members, essentially dying. I haven't been spending as much time on this as a result and progress is slow. I will continue working as I can and get some images up sometime soon. My Symasui layout is actually a fair departure from the original OS art...
 
From my last communication on the subject with OS I wouldn't stress too much about the pending 'upgrade' to the Spooky Leach IPS. It sounds like it will be relatively minor, so I'm inclined to pick back up on the artwork for Spooky.

I have Symasui almost complete and the Spooky Leach is probably 3/4 complete. I've got some very ill family members, essentially dying. I haven't been spending as much time on this as a result and progress is slow. I will continue working as I can and get some images up sometime soon. My Symasui layout is actually a fair departure from the original OS art...

This is bad news Jason, I'm truly sorry for this happening to you.:(
 
measurments again

some new measurments.
All these from "Spooky"
 

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Hi Jason,

Sorry to hear about your love ones. I will be praying for you.

I should have been paying closer attention. I thought the Spooky was further down on your list. I may wait and not populate the Spooky boards. I forgot how hard that was without screen print. I'm missing a few of the components anyway. Also I have been searching back through the thread and there is a lot of info on the Spooky. I see an option 2 and some of the schematics don't match up to well with the foil pattern I etched. Probably better to just wait. the only reason I etched those was because I already had the etching tank set up and I had extra boards so I just kind of picked one to try. I'm not sure if the foil pattern matches the latest layout. I think the last layout that OS posted was in a sprint file that I can't seem to open.

I have another question. In both Wolverine and the Spooky OS uses the KSA1015/C1815. Will KSA992/C1845 work just as well there?

OS, Happy Birthday!! Safe travels.

Blessings, Terry
 
Jason,
Sorry to hear about the illness in your family, I understand how that goes. I've been working on raising money for my project here so very busy doing that.

OS,
If you are watching the thread on your phone or something Happy Birthday! Have a nice safe drive and hopefully it will be nice at this time of year. Someday I would like to see what those Smokey Mountains actually look like in person, though we have plenty of mountains out here in California.

Thimios,
I am very surprised by the rapidly rising distortion numbers on the CFA-XH vs the Spooky. Perhaps someone can explain why that would be so, I though the CFA was supposed to be better on top and the VFA on the bottom of the frequency ranges? Is there a reason that the readings do not go past about 10Khz or is that just because you are using a sound card for the measurements?
 
Jason,
Sorry to hear about the illness in your family, I understand how that goes. I've been working on raising money for my project here so very busy doing that.

OS,
If you are watching the thread on your phone or something Happy Birthday! Have a nice safe drive and hopefully it will be nice at this time of year. Someday I would like to see what those Smokey Mountains actually look like in person, though we have plenty of mountains out here in California.

Thimios,
I am very surprised by the rapidly rising distortion numbers on the CFA-XH vs the Spooky. Perhaps someone can explain why that would be so, I though the CFA was supposed to be better on top and the VFA on the bottom of the frequency ranges? Is there a reason that the readings do not go past about 10Khz or is that just because you are using a sound card for the measurements?
Yes ,the only reason is that my sound card stops there by default(unfortunately)....
 
thimios
Measurements you posted today differ more than one order from measurmenets you posted in #3016 . It seems to be something wrong?
Measurements i posted in previous posts are with a different setup
The difference is that now i do a connection out gnd to line in
First setup
Next set up
What is the correct method doing this?
 

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and then connect ground (shielding)only of this looback cable to ground of amp
and make again loopback measurement, compare this with "clear" loopback. Results should remain unchanged, it should be the same picture as above. According your pictures, connecting input cable shield (so creating ground loop) worsen results more than one order of magnitude, for the same amp. Try to measure spectra e.g for 1kHz for both setup.
 
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