Group Build: Dynafet

[Icarium]

Yeah.. I'll get some exact quotes from the guy for all the features upgrades and then post an explanation regarding that.. I hope to do that by early next week latest.

[Icarium]

He hasn't given me an exact quote on the bigger heat sinks yet but he says they aren't much more money so I'd assume sub 5 dollars for that upgrade.

The better muse caps are an extra 2.15 (2.50 -> discount).

[PICaudio]

Ok, I want 2 Sigma 22 kits with Muse caps, big heat sinks and blue leds.

I haven't any problem to make a 4 ch Dynafet to my friend Carlos .

-- o --

Rodrigo

[Torpedo]

The Spanish gang has some suggestions which maybe you'd be interested in discussing:

- Making separate enclosures for the PS and the signal parts. This has the advantage, being S22 power supplies, that the PS alone could be used in the future to feed a B22, even a 6 boards unit. It also could save costs for the PS trannies. Noise, RFI shielding, and vibration damping is a bit less of a matter, and would allow using quite safely less expensive trafos like the Talemas which Picaudio and Hitori suggested.

- We've thought that it'd be a very interesting feature that the unit had two separate 2ch volume controls, so when using the unit in balanced mode each pot would control a single stereo channel, but when using the amp in SE mode, provided we put two TRS outputs for phones, then each pot could control separately each SE output. Hence it'd be like having 3 separate amps, one balanced with separate volume controls for each channel (like my Gilmore balanced Ref), and two SE with independent volume controls for each amp.

This can be easily implemented if using stepped attenuators (for channel balance when used in balanced mode), but we don't know how it could be implemented if using the SMD attenuators and the digital controller J4cbo is developing. Would it be feasible using the board?

[n_maher]

Crikey, I'll probably be in for a couple sigma22 kits w/ upgraded caps and heat sinks. If I may make a suggestion: see if you can get the heat sinks without the pins in them. I really dislike soldering heat sinks in place on builds like this. It makes them very hard to remove if you have to repair something. Also, removing the pins is a reasonable sized pain in the ass too. I just got done doing it to a dozen of them for a beta22 project I'm working on and it was not fun.

[luvdunhill]

Crikey, I'll probably be in for a couple sigma22 kits w/ upgraded caps and heat sinks. If I may make a suggestion: see if you can get the heat sinks without the pins in them. I really dislike soldering heat sinks in place on builds like this. It makes them very hard to remove if you have to repair something. Also, removing the pins is a reasonable sized pain in the ass too. I just got done doing it to a dozen of them for a beta22 project I'm working on and it was not fun.

The only thing I've noticed, is that the 2.5" height aren't available without pins.

[n_maher]

The 2" versions all come with pins as well.

One other thing to consider is that moving to larger sinks doesn't do much to help with junction temps and may complicate the casework quite a bit. A 2-1/2" sink eats up a lot of vertical real estate, I'd recommend going with 2" so that once mounted to the boards you can still use a 1/2" standoff and have some clearance in a 3" (1U) chassis.

[luvdunhill]

The 2" versions all come with pins as well.

One other thing to consider is that moving to larger sinks doesn't do much to help with junction temps and may complicate the casework quite a bit. A 2-1/2" sink eats up a lot of vertical real estate, I'd recommend going with 2" so that once mounted to the boards you can still use a 1/2" standoff and have some clearance in a 3" (1U) chassis.

If anyone is considering a 1U chassis, this will be the least of their issues

[Torpedo]

The 2" versions all come with pins as well.

One other thing to consider is that moving to larger sinks doesn't do much to help with junction temps and may complicate the casework quite a bit. A 2-1/2" sink eats up a lot of vertical real estate, I'd recommend going with 2" so that once mounted to the boards you can still use a 1/2" standoff and have some clearance in a 3" (1U) chassis.

Not sure, but that could be an advantage. You can use some thermal conductive material to make the heat sinks contact the top cover, so it would become part of the heat sinking.

[vvs_75]

No No You do not want the heat sinks touch the case.

[Torpedo]

Short might happen? Vibration? In my ignorance of technical matters and considering case heat sinking was an option, I thought it could be a good thing Would you please would be so kind to explain why to me

[Pars]

The 2" versions all come with pins as well.

One other thing to consider is that moving to larger sinks doesn't do much to help with junction temps and may complicate the casework quite a bit. A 2-1/2" sink eats up a lot of vertical real estate, I'd recommend going with 2" so that once mounted to the boards you can still use a 1/2" standoff and have some clearance in a 3" (1U) chassis.

A 3" case is 2U, not 1U (U = 1.75"). The 1U cases from modushop are 40mm; 2U are 80mm. The 2.5" heatsinks would make for a tight fit. And I concur on the pins... not knowing exactly what they were, I tried to desolder some in an MD10 I was fixing. I didn't try real hard, but I could not get them to budge. Threaded as the stock ones are is far preferable.

[naamanf]

You can desolder the pins with a vacuum station. Not so much with wick or a hand sucker.

Do we have final (or close to it) dimensions on the amp boards?

What about power figures on the them? If we had both then we could start looking into what size case and heat sinks we really need.

[Icarium]

Not yet on the dimensions.. I think j4cbo said ~1 more week and we should be good to go on ordering prototypes.

[luvdunhill]

You can desolder the pins with a vacuum station. Not so much with wick or a hand sucker.

Do we have final (or close to it) dimensions on the amp boards?

What about power figures on the them? If we had both then we could start looking into what size case and heat sinks we really need.

Power dissipation built to the schematic and the proposed boards will be 3.75W per device times 8 devices per board. Of course this scales up quite nicely, given larger heat sinks and potentially larger power supply rails. Figure 2.5 times more power than a beta22 and you'll be in the right ball park.

[n_maher]

Yeah, yeah, I meant 2U you bunch of nit pickers.

Bottom line, as Naaman said without some fairly special tools the pins can be problematic to remove. Maybe not a big deal here, I have only seen one failed sigma22 and that was under exceptional circumstances.

[Pars]

I figured you meant 2U, just wanted to make sure no one started ordering 1U cases

[Icarium]

4u or bust sir! well maybe 3u but yeah

[luvdunhill]

So, a bit of an update. Things are slowly coming together. I have 2 payments so far using "e-check", which there seems to be a flat $5 fee for using. I'd recommend using this. However, one thing to note is it can take a while. I really need a bulk of the money in my bank account (which means I then have to transfer from PayPal) on Monday. This is looking like this may be hard to do. So, if you're using an "e-check" I'd really like you to start the process by COB tomorrow. Same with mailing a paper check, or money order. If you're using other PayPal methods, you have a bit of time, but don't wait until the last second, please. Also, try and use a PayPal calculator to figure in the fees. Let's not drag this out too long guys.

Team Spain: YGPM

Icarium: Feel free to chime in if I missed any salient details.

[naamanf]

Shoot me a PM with your paypal (I think I have it already) and how much I owe.

[Looser101]

Shoot me a PM with your paypal (I think I have it already) and how much I owe.

x2

[Icarium]

Got you guys (Can skip the first part that is only really pertinent to the j4cbo build). If anyone else needs his mailing address or paypal info let me know. I know casino is google proof, but Luvdunhill would prefer me not to just paste his info in here and I'm going to respect his wishes.

Sorry for the extra annoyance overhead though.

[n_maher]

So, a bit of an update.

Marc,

Do you need payments for the sigma22 folks too or just the amp board folks? I can't keep up with where you guys are at with all the options, who's ordering what, which google spreadsheet is most current, etc. If someone needs money for the few parts that I want just let me know. If me purchasing a few kits is problematic I don't mind just ordering from Jeff directly.

[luvdunhill]

Marc,

Do you need payments for the sigma22 folks too or just the amp board folks? I can't keep up with where you guys are at with all the options, who's ordering what, which google spreadsheet is most current, etc. If someone needs money for the few parts that I want just let me know. If me purchasing a few kits is problematic I don't mind just ordering from Jeff directly.

no. We will pay Jeff individually, except for perhaps Team Spain.

[Icarium]

Marc,

Do you need payments for the sigma22 folks too or just the amp board folks? I can't keep up with where you guys are at with all the options, who's ordering what, which google spreadsheet is most current, etc. If someone needs money for the few parts that I want just let me know. If me purchasing a few kits is problematic I don't mind just ordering from Jeff directly.

Yeah sorry... what Luvdunhill is looking for is purely for Dynafet transistors which is separate to the sigma22 kits except in the weird Spanish situation.

I'll summarize and give out all the Sigma22 related details after I get a detailed quote based on peoples' locations from Jeff.

But the gist of it is you will get an exact quote including shipping based on your location and payment info for Jeff. Then you pay him based on that quote and he ships kits to you.