Lovoltech LU1014D power JFET - diyAudio
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Old 13th January 2006, 01:04 AM   #1
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Join Date: Feb 2001
Location: Columbia, SC
Default Lovoltech LU1014D power JFET

Some people frequent the Pass Labs Forum and some don't.
That's okay--it takes all kinds to make the world go 'round. We don't hate you...promise.
--but--
I will now give you an excuse to visit Nelson Pass's DIY site (www.passdiy.com). You see, there's a device that few, if any, of you have in your arsenal. In fact, very few people even know that such a thing exists. It's called a power JFET. Sure, you're aware of JFETs. Nifty little things. High Zin--close enough to infinite for all practical purposes, and quiet if you're into voltage noise (separate and distinct from current noise--bipolar fans go grumble somewhere else). Wonderful devices. Marvellous. Until you find that it's difficult to get more than a few milliamps through them.
Bummer.
The audio gods have heard your cries for help and have responded with the LU1014D.
The first thing you want to do is go to www.passdiy.com and read the Zen Variations 8 paper that Nelson wrote. Then you go to the manufacturer's website (www.lovoltech.com) and look at the datasheet for the LU1014D. It wouldn't hurt to look at a couple of the threads in the Pass Labs Forum for other hints about using these devices. Nelson already has a commercial design out using the LU1014D and more coming. If any of you are brave enough to build something I've cobbled together, I'll be posting a higher powered amplifier soon. It is my understanding that Nelson also has more diy-oriented projects in the works.
If you find that you want to build the Zen #8 or perhaps some other design, your next instinctive move would be to hit Mouser or Digikey. To no avail. Unfortunately, Lovoltech does not have a retail distribution network at this time. They're geared for the computer motherboard makers and sell directly to them. Little guys like us are left facing a rather hefty buy-in requirement (well over 2000 devices, minimum order). Uh, oh.
A group buy was initiated, but never quite developed critical mass. I, not wanting to wait for all the details to get sorted out, employed the Gordian Knot solution. I bought a bunch of the silly things out of pocket so I could get started on my own designs. In fact, I bought quite a lot of them.
I am offering the Lovoltech LU1014D power JFET at the following prices:

Unmatched
1 $1.69
20 $1.49
100 $1.39
200 $1.33
1000 $1.29

Matched (Vgs)
1-19 $2.59
20-50 $2.29
(Anybody who wants more than 50 matched devices needs their head examined.)

This is how it works--
--All prices in US dollars (not Australian, Canadian or other dollars). Personal checks okay. When your check clears the bank, the JFETs ship. My bank is the final arbiter as to whether a check is good or not. Sorry, no PayPal or credit cards.
--No minimum order requirement. You want 1, you get 1. You want 37, you get 37. You get the quantity you order. It's that simple.
--No handling fees or other oddities. The price listed above is it.
--Shipping will be pretty much at cost and as cheap as we can arrange it. For US (and possibly Canadian & Mexican) buyers, I can mail parts in a standard business envelope with minimal padding. They're small, fairly robust, and lightweight. This means that an average buyer will be looking at a few cents for an index card to tape the things to, a few cents for an envelope, and $0.39 for US postage. If you want the added cushioning of a padded envelope, that will probably add something like $0.75 to shipping. All told, an ordinary buyer here in the US will be looking at about $0.50 shipping if you go the envelope route. Nearly everyone will get out for less than a buck.
As I've said elsewhere, these things are about the size of your pinky fingernail. Even people who want 100 devices should fit into the envelope category.
I will try to accomodate anyone who wants UPS, FedEx, carrier pigeon, etc. but please try to be reasonable. The weirder it gets, the more hassle it will be for me, and the more it will cost you.
--No refunds. If the parts get smashed in shipment, return them and I will send replacement parts. If you blow them up and try to return them, I will hire a Voodoo priest to make your cat miserable.
--I will handle North America. David Briggs (dhole) has offered to handle European distribution. If you live in Europe, talk to him. No other arrangements have been made yet.
If, brave soul, you have made it through all above and haven't lost heart, this is what you do:
Tag the e-mail button at the bottom of this post and give me
1) Your DIY userid.
2) Your real name.
3) How many you want.
4) Whether you want them matched or unmatched.
I will respond with an e-mail giving you my address and a total, including shipping. Please do not pass on my contact information to anyone. If you've got a buddy who wants parts, get them to sign up here or order for both of you in your name.
Please be aware that matching takes time. I will almost certainly be slower to ship matched parts than unmatched. Be patient if you want matched devices. I promise to get them out as soon as possible.
Note that a post in this thread does not qualify as an order. Only a direct e-mail to me qualifies as an order.
If you have questions...ask. Either here or in the Lovoltech group buy thread in the Pass Labs Forum.

Your (more or less) Humble Servant,
Grey
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Old 13th January 2006, 05:35 PM   #2
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Join Date: Feb 2001
Location: Columbia, SC
This is a blatant cut-'n-paste from the other thread. I'm trying to save time for answering e-mails.
Oh dearie, dearie, me...
The floodgates have opened and lemme tell ya somethin'--the Mongol Hordes could learn a thing or two from DIY folks hungry for JFETs.
Okay, a little housekeeping. I'm getting e-mails that aren't including the basic info I requested:
1) Your DIY userid
2) Your real name
3) Your address
4) How many devices you want
5) Matched or unmatched
I even had one that was just a name, but none of the other info. No quantity, no address, nothing.
Sigh.
I've put the baby down for a nap (that's a joke, son, two year-olds don't sleep...ever) and am going to try to get a few e-mail replies out. I will attempt to get to everyone who has ordered so far, but don't panic if it's a little later in the day, or perhaps even tomorrow.
I'm fine on stock. You want 'em? Send me an order. I don't anticipate running out until 5 this afternoon. (That was another joke. Don't panic. I bought plenty.)
I've had an order from Indonesia and one from Australia. Technically, I'm not handling orders from that corner of the globe. I'm doing North America (Mexico, US, Canada) and David Briggs (dhole) is doing Europe. No one else has stepped forward to handle other areas yet. Now, if it doesn't get any worse than one order each, I may go ahead and deal with it, but I've always had the impression that Australia had more DIYers than the rest of the world combined. With that in mind, I anticipate more Aussie orders.
Let's do this--if you live somewhere other than North America or Europe, go ahead and send me an order. Warning: For the time being, I'm just going to let them pile up. Do NOT anticipate immediate shipment. If someone steps forward to handle a given area, then I'll forward the orders to them. If not, maybe I'll open a bottle of Lagavulin and try to work it through myself. We'll see. One way or another, we'll try to get JFETs to everyone who wants them, even if it takes a while. Sorry, but there's only one of me and I'm running on two hours sleep, which is scant even by my standards.
I've had one fella ask if it was okay if he ordered through a US member (he lives elsewhere in the world). Absolutely! I'm just trying to stay out of all the paperwork and junk involved in shipping overseas. If you live in, say, Peru (say hello to Paddington Bear for me), and have a buddy here in the US, then feel free to make arrangements with them. I'll ship to them, and they can ship to you. If you're happy with that, then it's fine by me.
Quick! Somebody fill my glass!

Grey
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Old 13th January 2006, 06:55 PM   #3
steenoe is offline steenoe  Denmark
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I will do the honours and make the first reply here then
Thanks a lot Grey, for doing this tremendous effort for the DIY community here at DIYaudio Its really appriciated

Steen
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Old 14th January 2006, 12:57 AM   #4
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Another cut-'n-paste...
If--and only if--you live in the US, you should have return e-mail from me by now. Given that I'm running on two hour's sleep and lotsa caffeine, double-check my math. If I did it wrong, please accept my apologies and drop me a line. We'll fix it.
Steen, you're included in the US batch. If you and your surrogate have not gotten e-mail, let me know.
I'll be tackling Canada later tonight or (more likely) tomorrow, but first I've got to research postal rates betwixt here and there.
Those from other corners of the globe, sit tight.

Grey
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Old 14th January 2006, 09:10 PM   #5
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At this time, all Canadian buyers should have return e-mail from me. If any Canadians have not heard back from me, prompt me with an e-mail or post here.

Grey
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Old 15th January 2006, 09:53 AM   #6
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Another update:
Folks, as a matter of both statistics and logistics, I need you to think in terms of smaller groupings for matched devices; perhaps 8, 10, or 12. I have people requesting very, very large single groups and it's approaching the point where I will have to strip the entire population of parts of certain values in order to make up the matched lots. Obviously, that's not fair to the members who want to match their own--they'll end up with holes in their values.
My intention is to try to hit 10mV windows, i.e. +-5mV. There may be one or two millivolts drift to either side, but that's my goal. If you approach it from a background in statistics--or if you refer to Nelson's Vgs curve posted elsewhere and work it through that way--you'll soon see that if someone asks for, say, 100 matched parts, it's going to require going through a huge number of individual units to meet that request. Huge meaning thousands in some cases.
Incidentally, I'm getting a slightly different distribution from the one Nelson posted. On his graph, there's a shorter bar to the left of the peak of the bell curve. Mine is just to the right, just doing an eyeball survey of the quantities I've graded so far.
Also note that these parts are not behaving the way tubes of IRF MOSFETs do. There's not a more-or-less smooth gradient going from one end of the tube to the other. I'll have a high value, then a low one, then perhaps as many as three or four that cluster towards the center, then back to another low one. Scattershot. I had one tube that had a notable preponderance of lower values, followed later on by another tube that leaned heavily towards higher ones. One tube clustered more towards the middle. The rest have been all over the map.
The devices do not have stamper numbers that might hint where they originated in the original wafer. I do not know what their manufacturing process is, nor do I know how they move their parts from manufacturing to packing. Presumably it involves a fair amount of jumbling around, judging from the value trends I'm seeing. Or lack of same.
Anyway, please think in terms of smaller sets. It'll make life easier for your fellow DIYer.
(Not to mention me...)

Grey
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Old 15th January 2006, 10:05 AM   #7
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And an update to the update:
My previous post is not meant to discourage you from ordering matched devices. Just plan on something like two sets of 10 or four sets of 12.
Yes, I know it's difficult to guess what you'll need when Nelson's Zen #8 only needs 1 per channel and I haven't posted my somewhat larger design yet. As guidance, think of an Aleph, where the active devices on top need to be matched as one group and the ones on the bottom need to be matched as a group...but they do not need to be matched together.

Grey
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Old 18th January 2006, 05:39 AM   #8
Stones is offline Stones  United States
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Quote:
Originally posted by GRollins
Mark Stones (mark stones, here on DIY) has offered to take orders for Australia and 'and the odd one or two orders overseas.'
I'm on a short leash at the moment--got to move on.
Thanks, Mark.

Grey
As Grey has pointed out I will be doing the Australia orders and one or two overseas orders that are around this side of the planet, unlike grey I will be doing this only once so if you are interested Email me your requirement prior to the 5th of February.

The prices will be whatever grey charges + postage + envelopes + tax (if I get charged then so do you) + share of bank transfer fee (for money to pay grey) + paypal if you pay me with that medium.

In short you will pay what it costs me nothing more hopefully nothing less.
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Old 19th January 2006, 08:50 PM   #9
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IMPORTANT: PLEASE READ IF YOU ARE ORDERING FROM CANADA
Without warning, my bank is charging a $16.75 fee for processing checks from Canada. This is a flat fee, regardless of the amount of the check. They say that it is a fee imposed on them by the Fed and that there's nothing they can do about it.
I have expressed great displeasure at having this sprung on us with no warning.
I don't yet know about Mexico, but checks from other countries will be more. It will probably be cheaper to do a wire transfer.
If you have not yet sent me a check, then add $16.75 to the total. Since this is a flat rate addition to the amount, you might consider stocking up and writing one larger check, but that's not my decision to make; it's yours.

Grey
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Old 20th January 2006, 03:45 PM   #10
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Join Date: Feb 2001
Location: Columbia, SC
Update for Canadian buyers:
paulb has come up with a suggestion that seems as though it will work. Get an international postal money order drawn in US$. We have been told that as long as it is in US$ it will not be subject to this absurd fee.
I will not rest easy until I see this in action, but let's try it.
Until further notice, Canadian buyers should use international postal money orders, not personal checks.
Those who have sent personal checks, don't panic. You did so in good faith. I will attempt to find other ways to avoid this fee.

Grey
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