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eXStata DIY Electrostatic Amp for Intermediate DIYers - Page 84  

post #1246 of 2969
11/30/09 at 5:27pm
all too easy to happen ..but never fear..like most Cavalli Audio designs, you'll be able to resurrect it, they are extremely robust.
post #1247 of 2969
11/30/09 at 5:44pm
Quote:
Originally Posted by runeight View Post
Sorry about that. But, there is the silkscreen ...

You might want to check the protection zener for Q4 before you fire up again.
i caught it on a visual inspection, so baring a few extra heat cycles all should be well
post #1248 of 2969
11/30/09 at 8:35pm
Thread Starter 
Folks, just some information, a few individuals have PM'd me for the last few boards. I am now out of hybrid board sets and I have two sand sets remaining.

Also, if there is someone who is interested but does not want to build right now I am willing to part with the sand amp that I built for testing. It works and is burnt in. Just my cost plus shipping.

Edit: I should clarify that this is not a completed amp, but only the fully populated boards. I am willing to include a 270AX as part of the package.
post #1249 of 2969
11/30/09 at 9:52pm
Thread Starter 
A question, slightly of topic, for those who have been paying more attention. Are the 2SK170/2SJ74 totally unavailable in new production? I know that Toshiba discontinued a while ago, but I haven't followed any further developments. And if so, what does the current stock of them look like at the various sources?
post #1250 of 2969
11/30/09 at 11:50pm
Quote:
Originally Posted by runeight View Post
A question, slightly of topic, for those who have been paying more attention. Are the 2SK170/2SJ74 totally unavailable in new production? I know that Toshiba discontinued a while ago, but I haven't followed any further developments. And if so, what does the current stock of them look like at the various sources?
For those that don't know, I tend to buy parts in volume. I recently bought 1000 2SK170 and 1000 2SJ74 from a contact in the Far East. He said that he cannot get anymore of these in the original Toshiba packaging. This is telling as he can usually get parts far past when something has been marked out of production. For example, I was able to only get around 200 of the violet grade parts about a year ago and according to him those were the first to be pulled (2SJ74V), as they are very low yield from whatever the production process Toshiba uses.

I think we have to keep pressuring Linear Systems to release the p-ch parts. There was a group buy that I headed up a while back that netted a $7K order, but even that is peanuts... nevertheless, I still hit up my local distributor here in Austin for Linear Systems every couple months and let them know that "we" (being the DIY community) would be very interested in doing a group buy that could potentially double the last one once the p-ch parts are released... they keep saying "very soon" or something to that effect, and probably is related to seeing what Toshiba does with these parts.

As for possible availablity, B&D is probably the standard place... Ebay being way to risky. But check what B&D wants for a 2SJ74V, a whopping $6 each.
post #1251 of 2969
11/30/09 at 11:52pm
At one point I had bought a few dozen pairs of the JFETs from spencer on diyaudio.com

But i know he is running low on the J74 and soon will be on the K170 as well.
post #1252 of 2969
12/1/09 at 12:19am
Thread Starter 
Marc, is Linear producing the nfet?
post #1253 of 2969
12/1/09 at 12:28am
Quote:
Originally Posted by runeight View Post
Marc, is Linear producing the nfet?
oh yes they are. Single and the dual. I have some if you'd like them...

http://www.linearsystems.com/datasheets/LSK389.pdf

http://www.linearsystems.com/datasheets/LSK170.pdf
post #1254 of 2969
12/1/09 at 12:32am
Thread Starter 
So they must be getting enough volume to burn their production lines on these. But not the pfets?
post #1255 of 2969
12/1/09 at 12:40am
Quote:
Originally Posted by runeight View Post
So they must be getting enough volume to burn their production lines on these. But not the pfets?
I suppose so. I'd have to guess that the tooling to produce the p-ch devices must be quite high. Like I said, I have a feeling that they are waiting to see what Toshiba does. Perhaps they will come out with an improved device? Linear System seems to almost be entirely founded on "direct replacement" devices, as well as doing what they call "All Devices are available with special testing to customer specification", in other words, they can do very tight matching on the devices for the end consumers. I can only expect if an improved device was released, that this wouldn't go over so well with their business model.
post #1256 of 2969
12/1/09 at 12:49am
Thread Starter 
I see what you mean. Makes it hard to design discrete audio if you need a good set of complementary audio fets.

Thanks for taking time for my detour.

How are the builds going gents? Seems like some of you are close?
post #1257 of 2969
12/1/09 at 12:51am
Regarding KSC5042, so either the 2sc3675 or 2sc3676 will work, as I have a stash of both?
post #1258 of 2969
12/1/09 at 12:51am
Quote:
Originally Posted by runeight View Post

How are the builds going gents? Seems like some of you are close?
Received the last of the parts..but feeling too lazy to smell solder fumes tonight. But will get to them soon
post #1259 of 2969
12/1/09 at 1:06am
Thread Starter 
Quote:
Originally Posted by pabbi1 View Post
Regarding KSC5042, so either the 2sc3675 or 2sc3676 will work, as I have a stash of both?
If I read the datasheets correctly, they are both excellent subs. In fact, I'd recommend the 76 for the hybrid because output fets there get hot as a result of being close to the tubes.

Edit: the KSC5027 would also be an excellent sub for the follower devices in the hybrid amp.
post #1260 of 2969
12/1/09 at 1:38am
Quote:
Originally Posted by runeight View Post
I see what you mean. Makes it hard to design discrete audio if you need a good set of complementary audio fets.
what about paralleling J271/J310 or even using bipolar devices?
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