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SOHA II Builders Thread - Page 30

post #436 of 1686
Quote:
Originally Posted by wiatrob View Post
Agreed, but I'd say aesthetics has quite a bit to do with DIY, but that's probably another thread (where perceived percentages of 'better' SQ are discussed). Otherwise all our builds would remain strapped to boards, and they'd be a heck of a lot quicker to finish!
I tend to put much effort and $$$ to higher SQ, but I think aesthetics will give more impact to resale value than boutique parts or contruction quality.

That 2 extra blue (yeah "blue" is very critical in this example ) LEDs may give your amp an extra 25-50$ in resale value...

But everyone know that we will all keep our SOHA II preciously
post #437 of 1686
Quote:
Originally Posted by regal View Post
Why not use the usual Digikey 35VA Amveco transformers? Will they not fit the standard Hammond enclosure?
Alex recommended the Avid transformer originally, so all I did was get "the next size up" from them. It is slightly larger physically, but bmwpower36(sorry bmw I know I spelled this wrong) was able to squeeze it into the Hammond case.

Quote:
Originally Posted by rds View Post
It doesn't improve the sound in theory only.
Are we talking cognitive dissonance here?

Quote:
Originally Posted by wiatrob View Post
Agreed, but I'd say aesthetics has quite a bit to do with DIY, but that's probably another thread (where perceived percentages of 'better' SQ are discussed). Otherwise all our builds would remain strapped to boards, and they'd be a heck of a lot quicker to finish!
Actually, casing the amp could have a functional benefit. It would help block out EMI.

I agree with you though. I did order several different LEDs to try out. I even ordered some connectors to make them easily swappable. But if I hear them (and I will be brutally honest when testing), they are gone. The tube glow will be enough for me
post #438 of 1686
Quote:
Originally Posted by wolf18t View Post
I tend to put much effort and $$$ to higher SQ, but I think aesthetics will give more impact to resale value than boutique parts or contruction quality.

That 2 extra blue (yeah "blue" is very critical in this example ) LEDs may give your amp an extra 25-50$ in resale value...

But everyone know that we will all keep our SOHA II preciously
The only way I would part with a DIY project would be if that was the intention all along.

I plan to keep my SOHA II forever though.

I'm actually looking forward to having a collection of headphone amps I have built. I'm up to 4 so far
post #439 of 1686
What size standoffs should I order for the amp? I am not using a hammond case so I will need to use all 7 standoffs. I want them to lift the board about 1cm off the case. Also I am about to place an order from digikey so if you know of a standoff there that will work please let me know.
post #440 of 1686
Quote:
Originally Posted by lacrossebowe8 View Post
What size standoffs should I order for the amp? I am not using a hammond case so I will need to use all 7 standoffs. I want them to lift the board about 1cm off the case. Also I am about to place an order from digikey so if you know of a standoff there that will work please let me know.
I had the same question. I can source standoffs locally though, so I'm just waiting until I get that close to finishing and I'll buy them at that point. Do you not have a hardware store nearby? I can get standoffs at my local Ace Hardware.

Quote:
Originally Posted by grendel23 View Post
I just finished my SOHA II, Very nice build, sounds great, a definite step up from my SSMH. now I need to save for HD600's.
Has anyone else noticed that the excel BoM is missing P1P, the pot to adjust the high voltage? Luckily I had one that would work.
http://i471.photobucket.com/albums/r...3/IMG_0967.jpg http://i471.photobucket.com/albums/r...3/IMG_0971.jpg
What bushings are those around the tube holes?
I'm not sure if Grendel will see this, so if anyone knows, please respond
post #441 of 1686
Quote:
Originally Posted by Hayduke View Post
What slot do you have the board in using 1/8" spacers?
I am not using the BOM case.
post #442 of 1686
Quote:
Originally Posted by Hayduke View Post
What bushings are those around the tube holes?
These are snap in plastic bushings from the hardware store. These were too tall, so I trimmed them down and glued them in with epoxy.

By the way, I have replaced my original top with one made of perforated aluminum. There was more heat building up around the tubes than I was happy with. I used 3003 Perforated Aluminum Sheet .063" x 12" x 24" - eBay (item 350114083531 end time Jan-20-09 09:49:57 PST). Once painted to match case, it looks great and runs much cooler.
post #443 of 1686
Quote:
Originally Posted by runeight View Post
You're welcome.

Here's an alternate way to wire the LEDs that might be preferable because it keeps the LED current out of the ground flow. RLED is calculated using 24V instead of 12V.



Edit: I've changed the drawing slightly to be consistent with common representations of dual LEDs. And, of course, one can always use individual LEDS.

I've also changed one resistor value. It's not important, but it does serve to equalize the base currents for the alternate version.
How much power is available here?
I'd like to have this circuit power the LEDs in the tube sockets. When the E12 circuit is triggered, it will power a separate LED, but when everything is OK, I want the tube LEDs to come on.

My thought is to put a bright red LED inside the case. So when the delay is on, the tube LEDs go dark and there will be a red glow coming through the various ventilation holes. When the delay circuit is being bypassed (ie music to the headphones), the tube LEDs come on.

I know you have already provided 3 LED circuits on the PCB. I already ordered the parts to possibly use 2 of these (based on noise as posted above), but I'd really like a visual indicator that the delay circuit has kicked in.

Alternatively, I can just hook up the red LED in the circuit provided, correct? Do I need to put the resistor in place for the other, unused, LED?
In other words, I really only care if the delay is on. I don't need the green LED in the circuit.

Sorry for all the questions. I ordered most of the parts, but then I realized I missed a couple small items. Since I'm placing another order, I thought I might like to implement this idea. If I have no sound coming from the headphones, I'd like an easy way to see if it was due to the E12 circuit.
post #444 of 1686
i do have plenty of hardware stores. I just wasn't sure they would have standoffs. Maybe I will get some tomorrow... if I can get anywhere due to inauguration.
post #445 of 1686
Thread Starter 
Quote:
Originally Posted by Hayduke View Post
How much power is available here?
I'd like to have this circuit power the LEDs in the tube sockets. When the E12 circuit is triggered, it will power a separate LED, but when everything is OK, I want the tube LEDs to come on.

My thought is to put a bright red LED inside the case. So when the delay is on, the tube LEDs go dark and there will be a red glow coming through the various ventilation holes. When the delay circuit is being bypassed (ie music to the headphones), the tube LEDs come on.

I know you have already provided 3 LED circuits on the PCB. I already ordered the parts to possibly use 2 of these (based on noise as posted above), but I'd really like a visual indicator that the delay circuit has kicked in.

Alternatively, I can just hook up the red LED in the circuit provided, correct? Do I need to put the resistor in place for the other, unused, LED?
In other words, I really only care if the delay is on. I don't need the green LED in the circuit.

Sorry for all the questions. I ordered most of the parts, but then I realized I missed a couple small items. Since I'm placing another order, I thought I might like to implement this idea. If I have no sound coming from the headphones, I'd like an easy way to see if it was due to the E12 circuit.

You should only draw about 10mA for everything powered by this circuit, whether it's one LED or many.

To use just the red LED replace the green LED and its resistor with about a 3k resistor. Then set the red LED resistor to provide 10mA or less through the red LED.

If you want mulitple red LEDs then put them in series and adjust the resistor according to the new voltage drop. You can probably run to a maximum of 10V in the LED string and then a resistor to set the current.

Does this help?
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 #446 of 1686
Quote:
Originally Posted by grendel23 View Post
I used 3003 Perforated Aluminum Sheet .063" x 12" x 24" - eBay (item 350114083531 end time Jan-20-09 09:49:57 PST). Once painted to match case, it looks great and runs much cooler.
Nice link, They've got some sexy hex perf as well...
post #447 of 1686
Thread Starter 
Quote:
Originally Posted by grendel23 View Post
These are snap in plastic bushings from the hardware store. These were too tall, so I trimmed them down and glued them in with epoxy.

By the way, I have replaced my original top with one made of perforated aluminum. There was more heat building up around the tubes than I was happy with. I used 3003 Perforated Aluminum Sheet .063" x 12" x 24" - eBay (item 350114083531 end time Jan-20-09 09:49:57 PST). Once painted to match case, it looks great and runs much cooler.
I made a perf'd aluminum top too and had it anodized. It is a pretty standard way to make a ventilated top, but it actually looks good and the amp runs at a comfortable temperature. Plus, I can see inside.
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 #448 of 1686
Quote:
Originally Posted by grendel23 View Post
These are snap in plastic bushings from the hardware store. These were too tall, so I trimmed them down and glued them in with epoxy.

By the way, I have replaced my original top with one made of perforated aluminum. There was more heat building up around the tubes than I was happy with. I used 3003 Perforated Aluminum Sheet .063" x 12" x 24" - eBay (item 350114083531 end time Jan-20-09 09:49:57 PST). Once painted to match case, it looks great and runs much cooler.
Thanks for the response AND the link!
I'll have to wander around my hardware store when I go get fasteners and stand offs.

btw, I love the way your case looks. I'm still undecided, but I'm considering copying your idea. That hammertone paint looks awesome! I have a lot of copper decor in my house. We have a coffee table and a sofa table, used to hold components under the wall mounted LCD TV, that are both hammered copper. That would blend well.

Quote:
Originally Posted by runeight View Post
You should only draw about 10mA for everything powered by this circuit, whether it's one LED or many.

To use just the red LED replace the green LED and its resistor with about a 3k resistor. Then set the red LED resistor to provide 10mA or less through the red LED.

If you want mulitple red LEDs then put them in series and adjust the resistor according to the new voltage drop. You can probably run to a maximum of 10V in the LED string and then a resistor to set the current.

Does this help?
That helps a lot! Thanks Alex.

So I'll just use only the red LED from the E12 circuit you supplied. The tube LED, if I use them, can stay on all the time

I will be happy to have a visual indication that the delay circuit is active.

My parts should be here this week, so I should be able to get it all assembled this weekend. I'm excited to hear this amp! I probably won't get the case work completed for some time though. If I use this perfed top, I might do it myself. Otherwise it has to ship to CA for my friend to work on it.

EDIT:
Just tried to check the status of my Mouser order and it appears it didn't go through on Friday
I probably never hit submit or something. Oh well now I can get the parts I missed into a single order.

Would anyone mind looking at my BOM and letting me know if you see any problems?

I changed some of the colors to indicate vendors other then Mouser. Also, a purple cell means I changed the part from the original BOM so it will be easier to see what is different.

Now to figure out what tubes to order
LL
post #449 of 1686
Quote:
Originally Posted by Hayduke View Post
Alex recommended the Avid transformer originally, so all I did was get "the next size up" from them. It is slightly larger physically, but bmwpower36(sorry bmw I know I spelled this wrong) was able to squeeze it into the Hammond case.

Should we add the Digikey Amveco transformer to the BOM? I'm sure people don't want to place a separate parts express order.
post #450 of 1686
Thread Starter 
My understanding (could be wrong) is that the Amveco transformers are rated before regulation and that they pull down below their spec'd values when full current is drawn. I read this, I think, on this thread.

Can anyone verify that this is correct or not? If it is true, then the amveco would not sub in this amp. And, obviously, if I'm wrong, we can put it into the BoM.
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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