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Old 27th March 2013, 08:03 PM   #1541
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I'd like to know how he has a room that isn't packed to the rafters with speakers and stuff.

I guess I'm doing it wrong.
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Old 27th March 2013, 10:15 PM   #1542
xrk971 is offline xrk971  United States
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Thanks guys. A foam core CD player is being planned... one of the best comments from the visitors was "that sounds better than any speaker I have heard - why don't they sell speakers like this?"
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Old 27th March 2013, 10:48 PM   #1543
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by Cal Weldon View Post
I'd like to know how he has a room that isn't packed to the rafters with speakers and stuff.

I guess I'm doing it wrong.
Cal,
The secret is to make mostly wall mount speakers that can be slowly coaxed into all the rooms in the house without taking up floor space. Swmbo raises an eyebrow when she notices a new set in a room previously 'unspeakered', but she has been a pretty good sport as long as they are unobtrusive and blend in with the walls. With this strategy I have managed to find a home for the FIB's in bedroom 1, the micro BIB in bedroom 2 (bookshelf size), the flat MLTL in the den, the micro Cornu's in the kitchen, and the mini Cornu's and the floor standing rear firing tapped horns have to share the basement rec room. Right now, the Cornu's are 'in storage'. But as you can see, I am quickly running out of rooms and will have to resort to giving them away if I produce anymore foam offspring
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Old 28th March 2013, 03:17 PM   #1544
Carlp is online now Carlp  United States
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OK, just a tad off-topic. Built a breadboarded PS for my phono stage but I was getting some hum. Decided I wanted to try it in metal for some shielding, but I didn't have a metal box on hand. I built a box of foam core, lined with aluminum foil, then tried it out.

As it happens, the hum is coming from the TT and cartridge coils, and aluminum foil isn't a good shield for magnetic EMI, so the box did nothing for that. It did, however, let me do testing more safely than with the bare breadboard.

Built the box slightly larger than the board, dropped the board in, soldered a few connections, now I have a box with a switch and LED power indicator. Temporary of course, but functional.
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Old 28th March 2013, 03:20 PM   #1545
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Cool! I love the quick and easy way this technique allows fast prototyping.

Did you ground the foil? Without it grounded it won't do anything.

Hum in a phonostage is almost always a grounding problem, not PSU noise -- keep at it, you will discover the culprit, usually something simple.
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Old 28th March 2013, 03:55 PM   #1546
xrk971 is offline xrk971  United States
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I put an aluminum foil groundplane (glued with rubber cement then glued bond paper on top of foil) on my foam core substrate for my amp. Connecting the aluminum foil to the ground pin with crimped connector screwed onto foam core board removed the 60 Hz hum that the amp was picking up (see photo below). Worked very well for prototyping a hairy SMD circuit.

6L6 is right, not connecting the aluminum foil to ground did nothing. Most project cases are aluminum so it is the RF that it is shielding. To block magnetic you need to use special "Mu-Metal" material.

Click the image to open in full size.

One more thing, I am a big believer in using SMPS bricks whenever possible because they are cheap and get you away from the 60 Hz hum. Generally they are not in the box, and the switch frequency is ultrasonic. I used to build PS just like the one CarlP shows - a Xformer, diode rectifier, cap, and 78XX regulator. Now I just use a $5 laptop brick. If you need 5 V put the 7805 after the 19v. They even make pin-compatible switch mode 78xx's that are 90% efficient.
http://www.murata-ps.com/data/meters/dms-78xxsr.pdf

Last edited by xrk971; 28th March 2013 at 04:03 PM.
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Old 28th March 2013, 04:48 PM   #1547
Carlp is online now Carlp  United States
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Foil is connected to mains ground. Center tap on secondary floats as I've full wave rectified the old 25.3v filament transformer. Using a LM317 set to 24v (23.76 to be exact). Just trying to see if I could build a quiet, cheap PS for a project that needed it, to be honest.

Most of my building is from free/scavenged parts, so even if I could get a $5 smps at 24v (I can't) I probably wouldn't. I learn so much more by doing it myself. But I do have a smps on a SE mosfet amp that is surprisingly quiet (better than any linear PS I built for it). So I'm not wholly opposed to spending $ and using smps.

6L6, interesting name with your list of gear...
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Old 28th March 2013, 04:56 PM   #1548
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Quote:
Originally Posted by Carlp View Post
6L6, interesting name with your list of gear...
Lol.



Not a simple list, but build guides.
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Old 29th March 2013, 02:10 AM   #1549
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by Carlp View Post
Foil is connected to mains ground. Center tap on secondary floats as I've full wave rectified the old 25.3v filament transformer. Using a LM317 set to 24v (23.76 to be exact). Just trying to see if I could build a quiet, cheap PS for a project that needed it, to be honest.

Most of my building is from free/scavenged parts, so even if I could get a $5 smps at 24v (I can't) I probably wouldn't. I learn so much more by doing it myself. But I do have a smps on a SE mosfet amp that is surprisingly quiet (better than any linear PS I built for it). So I'm not wholly opposed to spending $ and using smps.

6L6, interesting name with your list of gear...
Carlp,
24 v smps is another story.... 19 v is cheap because it is the standard laptop ps. Although you can tie two 12 v smps bricks from LCD monitors or external pc hard drives together to get 24 volts or plus minus 12 volts. The SE mosfet amp powered by the smps, wouldn't happen to be the Pass ACA would it? I am getting ready to build that.
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Old 29th March 2013, 02:27 AM   #1550
Carlp is online now Carlp  United States
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Huh, hadn't thought about tying two bricks together. For some reason, I guess I didn't think you could do that, but it makes some sense. The SE mosfet is a 2sk1058 design over at diyaudioprojects. I'm mostly a tube guy, but I just had to try the sound of one transistor clapping, and it seemed like a simple and INEXPENSIVE schematic. Plus I had a relatively inexpensive smps at my disposal. Not a wall wart though. Cheers.

Oh, and surprisingly nice sound from those 2sk1058s at a whopping 5 watts (far more than I typically need with my Pass BOFU full rangers, to get back to the full range speaker topic...).

Last edited by Carlp; 29th March 2013 at 02:30 AM.
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