UFN
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Posts posted by UFN
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Interesting as usual and agree on the BC-parts - if they disappear then I think we might as well close up shop
BTW, isn't it the 549/550 and 559/560-versions that are supposed to be "audio" parts and the 546/547 and 556/557 are intended for switching?
//UFN
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If you mean the Dynalo, then yes I have (amp boards only, no PSUs)
//UFN
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Old thread, sorry: Kevin, do you have a schematic for the current version of this board?
//UFN
EDIT: Oh, and some BoM-questions:
1) I assume the diodes are just standard 1N4148/1N914?
2) Is the 47uF cap supposed to be ceramic or similar since it hasn't got the same footprint as the electrolytics?
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Very neat! Was going to complain about the onboard IEC-inlet, but it's quite obvious you didn't have other options
//UFN
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Spritzer, one more question: I assume this means the Gerbers posted for the KGSSHVstereo are fine as-is and no changes are required?
//UFN
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Very neat! I am really in love with the small stereo board, but I should probably finish my "normal" KGSSHV first
//UFN
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Way ahead of you...
//UFN
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Very nice! What case is that?
//UFN
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Thanks Kevin!
//UFN
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I have some Squarewave boards on the way, and I was unable to find instructions on how to measure bias and what values are recommended. Can anyone help?
//UFN
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Finished my KSA5 and am very pleased after a relativly short listening session. Board parts are standard from the BOM with extra attention paid to closely matching the parts. Goldpoint controls, Vampire RCA's, SUMR transformer. A big thank you to Kevin Gilmore for making this project possible!
<snip>
Me
Nice work on that chassis!
//UFN
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1.5VDC? That's a lot and I think the servo can't eliminate that much offset.
Were the inputs grounded (or the pot installed) when making the measurement?
UFN, there is obviously a fault.
For a 2N5564 with a data sheet specification for maximum offset of 5mV between the pair, this circuit should see a maximum of 25.6mV output offset for a worst case 2N5564 with the servo disconnected.
This thing doesn't need a servo if it's using a matched input pair like the 2N5564. The servo can be removed and a trimmer potentiometer used to trim R3 and R4 to shift the drain currents of the input pair to null the input offset and therefore the output offset.
R45 could be removed and R46 replaced with a 750Ω resistor to keep the gain the same. With the added benefit of removing the LF pole created by C8, C9 not the least the extra distortion caused by those electrolytics. So a true DC low frequency response.
Thanks for the replies guys, I have been away and unable to retest until today. I was pretty sure I had the inputs properly grounded last time, but I removed the board from the case, reflowed a couple of suspicious joints and then retested it with better cabling. Now I get around 8mV on one channel and 22mV on the other without the opamps, and less than 5mV on both channels after fitting the opamps again.
Not sure what exactly the problem was, but it looks like I've fixed it
//UFN
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Many of the things that On-semi are now dropping seem to have equivalents (or near-enough equivalents) from Fairchild and others, except if you need/want the MPSW 1W package.
That said, I'd never thought I see the day where I considered stockpiling BC547Bs just to be safe...
//UFN
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The feet are off ebay but not the ones I actually ordered. Gotta love ebay for shit like that...
Yep, if you want to be sent something else than what you actually ordered, ebay is the place to go
//UFN
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Crossposted from diyaudio: http://www.onsemi.com/pub/docs/pcn/PD20685.pdf
On-semi are discontinuing all of their TO-92 products because of a disagreement with a subcontractor. List includes all the MPSWs....
//UFN
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I'll of course join the choir and say "excellent work"
If I ever send an amp to a show of any kind then it will have a lexan top panel. Heavily ventilated naturally but it would be a nice fuck you to those who hide the internals.
Speaking of which, can we see some topless pics of her Spritzer?
//UFN
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So nothing out of the ordinary as long as putting the opamp in will zero it out? Was just surprised that the difference is that big based on previous posts here
//UFN
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Have now finished putting the amp together and without the opamp in place I get around 7mV offset on one channel, but around 1.5V on the other. The amp otherwise seems stable although I haven't listened to it yet. Any ideas as to what i need to check to find the problem?
//UFN
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<snip>
Here is what a stereo KGSSHV board looks fully populated.
Lovely! Is it working as expected? Would love one of these as my next project
//UFN
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So LSK389A (hard to source in old Europe !).
I bought from Micross in the UK (https://www.micross.com/ecommerce/shop-default.aspx) Their postage charge is still high, but more reasonable than trendsetter and there is no risk of additional customs charges since it is from the UK. Also, I got my parts delivered within the same week as I placed the order.
//UFN
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Has anyone built their KGSSHV with a Joshua Tree attenuator? I'm wondering if I connecting it to one of the 16VAC secondaries would have any adverse effect on the amp. The JT doesn't use much power and it would save the trouble of installing another toroid. Thanks.
Well, based on TPA's published specs I can't see that that should be a problem.
//UFN
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ST = "Single Triode"
//UFN
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You can do this from the Gerber files if you have an image editor that can change the print resolution of an image without changing the actual size of the image (such as Photoshop).
1) Download gerbers from Kevin's usual place.
2) View gerbers on circuitpeople.com.
3) Download the generated images at a decent resolution - 2-300 dpi should be fine.
4) Open the silkscreen layer image in your photo editor.
5) Change the print resolution to whatever the original images were generated at by circuitpeople without changing the pixel size of the image (in Photoshop this is done by switching off "resampling" in the "Image size" dialogue).
6) Print from your image editor either directly to paper or to a file without scaling ("fit to page" or similar) applied.
7) Check you printout against the boards - they should match.
//UFN
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Still working on my "normal" KGSSHV, but that looks very cool!
//UFN
EDIT: Left out the obvious part: Want one!
balanced headphone protector
in Do It Yourself
Posted
Well, it seems the 25V part is backordered at Mouser until February. I haven't done anything yet, but maybe a 47uF bipolar electrolytic will work instead? Looks like you can get at least an 8mm part into the board (and maybe 10mm at a pinch).
//UFN