[Earwax]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif All that said, I may revise the listings sometime this weekend. We are in danger of not even getting requests for 30 cases, the absolute minimum needed to order from Hammond. I'm open to ideas that are still in the interests of fairness. The first thing I was thinking was to allow multiple orders per person and/or perhaps creating a "case+tubes+PCB" listing. Comments are welcome - I'd hate to say we can't get cases and send out refunds.

Thanks for your efforts TomB!

I would prefer to buy Case+Tubes+PCB set personally, I might even get two if that were offered. Otherwise, I intend to wait for the first 30 to run out so I can get a kit w/o power supply.

 

[Juaquin]

I went for a full kit. Whatever needs to be done to get this thing going is fine by me.

Also, would it be possible at some point to offer a second set of tubes (or even a single tube) to people who bought kits? With the growing scarcity of those tubes, I'd like to have a couple extra on hand should they ever burn out.

 

[tomb]

Right now, the case count stands at 20. That's enough for me to order 30 on Monday. We'll have two weeks to add to that number.

I'll add some more options tomorrow - PCB's + tubes and other parts.

 

[royewest]

I've recently switched jobs and now work for a company that writes software for cell phones and related devices. This means I'm surrounded by devices that emit RF. The two MSSH amps I tried in that environment (one point-to-point, the other a PCB prototype) were pretty unlistenable with interference.

I bought some brass screen and am going to see if I can create a Faraday cage with it (while wearing my foil hat). One point about F cages is they must be grounded. I think the MSSH amps are not really grounded (not to earth, that is), because they are using ungrounded power supplies.

So my question is, is there any reason not to tie the ground of a MSSH amp to real earth ground? For example, bolt a wire from my case (whether or not connected to the star ground) to a banana plug inserted into the grounding hole in a grounded outlet?

Thanks in advance for any advice that will prevent me from damaging myself or these sweet amps.

__Roy

 

[wankski]

thanks for your words tomb!

just so you know, i don't need power supply or case.... just pcb kit and tubes as an alternative would be great down the line when ur sorted with min cases orders. But i understand if you don't wanna.

 

[rds]

Quote:

Originally Posted by royewest /img/forum/go_quote.gif One point about F cages is they must be grounded. I think the MSSH amps are not really grounded (not to earth, that is), because they are using ungrounded power supplies. So my question is, is there any reason not to tie the ground of a MSSH amp to real earth ground? For example, bolt a wire from my case (whether or not connected to the star ground) to a banana plug inserted into the grounding hole in a grounded outlet? __Roy

A Faraday cage does not need to be grounded. Actually, I believe that once you ground it, it's not actually a Faraday cage anymore.

However, in this case I think what you really want is a shield that is tied to signal ground; and the shield only needs to surround the tubes. Try rolling a piece of tin foil in a cylinder and placing it over the each tube. That should stop the noise (if the tin foil is in contact with something that is tied to signal ground - like the case), but obviously is not a very attractive solution.

 

[cms5423]

Uh you definitely want to ground the F cage, if you don't, then any accumulated charge just sits on the cage, if you do ground it, it will dissipate anything into the earth ground... that's what a faraday cage is supposed to do. otherwise it would just accumulate all the charge/interference and hold it there

 

[Juaquin]

Tying to ground is the idea - any stray interference is picked up by the cage and it has a nice return path to ground. Of course, not tying it to ground is still a faraday cage - think of an airplane being hit by lightning. It's not tied to ground and yet everyone inside is fine.

 

[Llama16]

Hey all

(I'm sure tomb saw me coming from afar

)
my first post in the thread

. I've been trying to read whole the thread for a while now but still am just at page 60. It's pretty interesting and helpful when reading everything, and gives alot better idea of what to do when I'm going to build it and how the starving student actually works, which is really interesting.

I've already made a seperate thread in which I posted my questions about the order for components I'm planning to make at mouser. And tomb adviced me to post my questions here, and he's completely right about it.

I'll just copy it, or most of it:

Quote:

I was thinking about ordering the components for my first starving student together with my first MINI³, so I'd save alot of shipping (mouser=20euros in europe :S) As I always am pretty unsure of what to order and if I'm ordering everything correctly, not missing something. I downloaded the starving students component PDF (which pmillet was so kind to put up for us ) and checked everythings availability. I checked everything that was available, I put a small question with those that I was unsure about, and I searched for replacements of one component that wasn't available. So my question is: would you guys be so kind to take a quick peek at it and tell me if everything seems ok, or if you would prefer some other components in there that would come out better. BTW: I will be primarily using this amp with the HD650, so is there anything that i can replace to make it more suitable for this high impedance headphone? (other caps?) HERE's THE LINK TO THE XLS (I'm srry about the crappy upload host, I just picked one quickly) starving_bom.xls Thanks alot in advance Dries

Some extra questions that popped up (yet again, they may be very unimportant)
1) Is it best to buy my tubes and sockets at Beezar, now they're available (are they available seperately?) or should I still go with the, by pmillet, mentioned radiodaze? (I'm in europe)
2) What powersupply and where to get it, if I live in europe with has plugs of 220/230V? I tried ebay, but they're not available, also mouser doesn't sell PSUs and I didn't immediately found them in some european shops.
Let me know here you bought it or where you would have better bought it and which one.
((((3) This maybe doesnt belong here but o well, while I'm at it... a 9v 325 NIMH mAh for the MINI, where can I find it. preferably in on of the same shops as where i'll be ordering other parts. I don't really like to have alot of orders open, especially when this is the first time ever to order something online

.

I also want to apologize for maybe asking questions that may already be answered in this thread, but as I've already said, I'm reading the whole thread post by post already.
And as it is stalling the order for my MINI³ as well, plz don't blame me for maybe doubleposting this.

Dries

 

[Llama16]

EDIT: I pushed refresh, so the same post was doubleposted, Srry

 

[tamasic1]

The power supply for this project is the Cisco PSA-18U. Like almost all computer equipment today it runs on either 120 or 240v. It powers Cisco wireless access points (ap) and ip phones. One is included with every wireless ap however its rarely used. Most ap are connected back to a Cisco ethernet switch in the data closet that provides power through the ethernet wiring. The power supplies are abundantly sitting it boxes in network storage closets collecting dust. If you know someone in the computer field ask them if they or a colleague have installed or work with Cisco access points. If so there’s a good chance you’ll score at least one. Techs who work for a large company or school district would be your best contact.

 

[Llama16]

Thanks for the tip,
I doubt my school uses Cisco, thought it can't hurt asking.
At least I have something to look forward to and maybe they have one sitting around.

I'll see if I can find one on the internet. And I'll post it it here to make sure it has the right specs (you never know, and I especially don't, when there are some hidden features that are vital to it)

Dries

 

[Llama16]

I double posted again!!
My browser is doing this alot lately. I post and it says 'wait 30 seconds before...' and I wait and then I see my message 2 times. i didn't press refresgh, return,...
I'll try and figure it out.
BTW

this is the one I found: Marktplaats - De plek om Nieuwe en Tweedehands spullen te kopen en verkopen
I know it's in dutch, I don't know the full specs yet but I sent the seller a PM.

ALSO: what do you guys think about the rest of my list of questions and BOM? :S

Dries

 

[tomb]

Quote:

Originally Posted by Llama16 /img/forum/go_quote.gif I double posted again!! My browser is doing this alot lately. I post and it says 'wait 30 seconds before...' and I wait and then I see my message 2 times. i didn't press refresgh, return,... I'll try and figure it out. BTW this is the one I found: Marktplaats - De plek om Nieuwe en Tweedehands spullen te kopen en verkopen I know it's in dutch, I don't know the full specs yet but I sent the seller a PM. ALSO: what do you guys think about the rest of my list of questions and BOM? :S Dries

That power supply looks close, but not identical to all the ones I've seen. There's no mention of amperage (0.38A on the genuine), so that throws a little more doubt into it, too. It may be OK, but I bet you can find one that's absolutely identical and has all the right numbers:
Cisco PSA18U-480C AC Power Adapter 20V & Above
Cisco Original PSA18U-480C 34-1977-03 AC Power Supply 48V 0.38A For AP-350 AP-1100 AP-1200 and CP-7960G CP-7914 CP-7940G VOIP Phone [US-Cisco-PSA18U-480C] - $12.99 : Digital Surveillance spy Cameras, spycam, Computer Hardware, crystal, toy
Cisco / Delta Power Supply (48V / .38A) 34-1977-03 A0
CISCO PSA18U-480C 34-1977-03 Power Supply for Aironet Access Point or VOIP Phone (I don't think this website is actually working.)
http://www.norsystems.net/cgi-bin/p?...mno=ciscoAC48v

RadioDaze has been out of 19J6 tubes for a long time, now.

As for tube sockets - I'll be putting up some inexpensive silver ones today, along with some other parts and a "tubes+PCB" listing. Also, I'm removing the one-per-customer limit on the kits.

So far, about 20 cases have been spoken for. That's pretty good so far, so I'm going to order 50 of them tomorrow. Ya'll keep in mind that the PCB was designed for the case and vice-versa. It seems to me that it wll be pretty difficult to come up with a heat sink arrangement without the case. I'll continue work on the website, too - that will make things more clear.

 

[Llama16]

Thanks for the links I'll check them out as soon as I'm finished reading some 40more pages of this thread

. The guy I asked the specifications to still hasn't responded (he put the offer online yesterday, so I'm quickly at it)

Congrats with the kits, hope they will keep growing, I think they will. You'll already probably have, but I'm sure other sites would be interested as well.

I'm pretty new here so fill me in. of what I read in your post it seems like you made the website, and some posts earlier I think (I REALLY ain't sure

it could have been a dream)I read that dsavitsk and millet work together with you about those things? That's awesome, you guys know eachother RL or just by the internet you keep track of things.