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SOHA II Builders Thread - Page 37

post #541 of 1686
Quote:
Originally Posted by rds View Post
Wiatrob -
Similarly could the usb jack or exposed part of the usb cable be touching the case?
My Dacmagic is insulated, my Alien is uncased and sitting on a rubber strip. I solved the noise problem at hone. iMAc has optical out!


Quote:
Originally Posted by rds View Post
I have to take exception that. That is bad advice. The power supply is grounded for a reason. .
As I pointed out. However, on the continuum of Dangerous Things, ground lifting is toward the 'safer' end, But as electricity is invisible and bad advice liable, it's probably best to find another solution...
post #542 of 1686
Thread Starter 
Quote:
Originally Posted by Hayduke View Post
Since most (all?) laptops have a power block, the ground on that third prong ends there. Once it hit's the transformer, it's not doing anything. Waitrob has it right. That third prong is to help avoid a shock of something goes wrong. So short answer, it's fine to run the laptop that way. If you have an extra of the cord that goes between the power block and the wall, just break off that third prong. I did this to the power source for my Starving Student to try and get rid of hum, but it had no effect

/\_/\_/\_/\_/\_/\_/\_/\_/\_/\_/\_/\_/\_/\

Well I finished building my amp tonight, sorta. Other then the part I missed in my order

Funny part is, it was mentioned that P1L and P1R were missing from the BOM. It got added, but it is listed incorrectly as P2R and P2L. There are 2 items for those locations. When I was building my BOM I think I deleted the 200ohm trim pot thinking it was something that had been changed. I didn't notice there was no P1R or P1L.

Oh well, I was really hoping to listen to it this weekend, but I'm too cheap to pay for 2 day shipping for $5 in parts lol I guess it will be sometime midweek before I get to hear it. I already placed an order with Digi-Key for the trim pots. Naturally I was able to find other things to order.

FYI, if anyone is thinking about socketing Q1-8, it's a major PITA! The sockets for Q6 and Q7 aren't too bad, but I used the same DIP sockets as the test points for all the TO-92 transistors. So 6 per channel, 3 pins each. That's 36 tiny little sockets to solder

Also I discovered my tube sockets don't have a hole through the center for the LEDs There are some silver circles where the holes should be. I poked at them hoping it was just some thin foil-like cover, but no luck. I might take a drill to them if I decide I have to have the LEDs under the tubes. Otherwise, I might just use the 3 LEDs to light up the inside of the enclosure and have it shine through the ventilation holes.
@!%#&@&*)#^@#

I'm sorry. I just didn't see that in the BoM. I'll fix it, but not in time to help you now.
Dr. Cavalli gained notoriety with his first DIY amplifier projects. His success has blossomed into Cavalli Audio, a world leader in amplifier design.
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post #543 of 1686
Quote:
Originally Posted by rds View Post
I have to take exception that. That is bad advice. The power supply is grounded for a reason. It is there in case the neutral were to get broken at some point (in the cord, the wall, a power bar etc).
Also, just having a 3 conductor cord with the ground removed laying around is a hazard in itself. Who knows what someone else might try to use it for not noticing that the ground has been cut.
I suspect the reason it's grounded has more to do with liability and the litigious nature of the US then any real need, but you're right that is less safe. I never claimed it was ideal I only did it to test, and it didn't help anyway hehe

As for having the modified cord around, that could be true, but it's just me and the wife here, and she wouldn't go rummaging through workbench area for a power cord

Quote:
Originally Posted by runeight View Post
@!%#&@&*)#^@#

I'm sorry. I just didn't see that in the BoM. I'll fix it, but not in time to help you now.
No worries Alex. I should have caught it. Like I said, I did realize it at one point, but somehow it never made it into my final BOM.

Thanks for fixing it though. It may help another builder


EDIT: so there was some good in having to place another order. I had forgotten the zeners for R4 since I went though the trouble of installing sockets there, it would be nice to have the parts lol

I ordered all 3 brands of 18V 500mW zeners that Digi-Key had. Hopefully at least one is less noisy. Big price difference. The Fairchild's that someone else used earlier in the thread were only 8 cents, but the other 2 brands were 33 and 46 cents!

If anyone had a recommendation for an R4 zener from Digi-Key, a link would be appreciated. I can change my order until Monday morning
post #544 of 1686
Quote:
Originally Posted by Hayduke View Post
Also I discovered my tube sockets don't have a hole through the center for the LEDs There are some silver circles where the holes should be. I poked at them hoping it was just some thin foil-like cover, but no luck. I might take a drill to them if I decide I have to have the LEDs under the tubes.
Hayduke, don't do this. I did it and I end up with one of the two tube socket slightly damaged. That silver part is used to hold the upper and lower portion of the tube socket together.
post #545 of 1686
Quote:
Originally Posted by wolf18t View Post
Hayduke, don't do this. I did it and I end up with one of the two tube socket slightly damaged. That silver part is used to hold the upper and lower portion of the tube socket together.
If you drill out the plug carefully, the two halves can be glued back together (I used construction adhesive). The trick is to use a drill bit that's just big enough to break through the rolled over lip portion of the metal plug holding the socket together.

I've done this for several sockets.
post #546 of 1686
Quote:
Originally Posted by wolf18t View Post
Hayduke, don't do this. I did it and I end up with one of the two tube socket slightly damaged. That silver part is used to hold the upper and lower portion of the tube socket together.
Quote:
Originally Posted by kklee View Post
If you drill out the plug carefully, the two halves can be glued back together (I used construction adhesive). The trick is to use a drill bit that's just big enough to break through the rolled over lip portion of the metal plug holding the socket together.

I've done this for several sockets.
hmmm.. thanks for the feedback guys. I considered ordering some different sockets, but they seem like they would be difficult to remove with all that solder.

That does make sense what it's for. if I only used a drill bit narrow enough for the LEDs, it wouldn't remove all of the silver material in the center. Maybe the 2 halves would stay together. If all it does is hold the 2 ceramic pieces together, then I can always use kklee' suggestion and glue them together.

The LEDs aren't that important to me, so I may not do anything about the sockets at all
post #547 of 1686

The best 12AU7 tubes

Hi guys,
Which manufacture did make the best 12AU7 tube? RCA, Sylvania?
Which 12AU7 would be the best for Grado RS1?
I heard that the RCA Cleartop is the best of the best but i don't know the real truth.. Which is the "real best if the best" ?
post #548 of 1686
A quick dry fit of my balanced SOHA II in the making. Everything seems to turn out as I have on my mind.
Due to my busy work schedule (and various giant builds at the same time )… still far from finish though.


post #549 of 1686
Quote:
Originally Posted by Ferrari View Post
A quick dry fit of my balanced SOHA II in the making. Everything seems to turn out as I have on my mind.
Due to my busy work schedule (and various giant builds at the same time )… still far from finish though.
Please, let me be the first to say: Whoaaaaaaa!!!!!!!!

Really impressive, as always
post #550 of 1686
Thanks for the kind words. I wish that I had the time to complete it.
post #551 of 1686
Quote:
Originally Posted by Uncle Bob View Post
I'm still here, and unfortunately I still have the hiss problem - I just haven't had the opportunity to sit down and work on the board. I will keep you posted on progress - I still have to make an enclosure for it. I can't consider it a finished project until it's all cased up.
Did some checks on my problem SOHAII today. All voltages checked out OK but I went over all the solder joints in the left channel anyway. Still got that hiss problem in the left channel. But I've found that minor flexing of the PCB makes the hiss come and go - so it seems I have a fractured connection somewhere (after I dropped the board). I've gone over the PCB with a magnifying lens but I cannot see any fault, but there must be break somewhere.
post #552 of 1686
Sad to know, Uncle Bob. Hope that you can figure that out, sooner or later.
post #553 of 1686
Quote:
Originally Posted by Ferrari View Post
A quick dry fit of my balanced SOHA II in the making. Everything seems to turn out as I have on my mind.
Due to my busy work schedule (and various giant builds at the same time )… still far from finish though.


Great workmanship Ferrari, as always. Where did you get this case? I like it a lot, seems like it's from an old Rotel integrated.

And what are the meters? Voltage or power meter? These are very cool add-on.
post #554 of 1686
Ferrari, do you do your own casework?

Your builds always look incredible. This one is no exception

I'd love to see some pics or guide to how you do you casework. Like what tools do you use and such.
post #555 of 1686
Quote:
Originally Posted by wolf18t View Post
Great workmanship Ferrari, as always. Where did you get this case? I like it a lot, seems like it's from an old Rotel integrated.

And what are the meters? Voltage or power meter? These are very cool add-on.

As a big fan of Accuphase, Marantz and Rotel for years… I’m undoubtedly inspired by them, in one or other way. Now you are talking about Rotel, I do have a set of Rotel Michi RHA-10/RHB-10 pre- power amp combo from the ’90 at my place. The symmetry, red illuminated ring are indeed inspired by Rotel.
(The red ring on the Rotel pre-amp is non- illuminated red plastic, however.)

The case for my balanced SOHA is originally a HiFi-2000 Galaxy GX348. I designed the front-, back- and top panels and let them milled/engraved by Schaeffer AG (FPE in Europe). The effective high of the case is modified (from 40mm) to 50mm to accommodate the use of 1.5” heatsinks.
The meters are current meter (output signals). It’s there more for the looks.
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