"Equal Opportunity" MM Pre

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Here's a suggestion input stage, filter and buffered output on one card measuring 3.5 x 8.0

Hello all. I've been lurking and hoping to build one of these, so you can add another to the list.

Personally, I'm OK with the one board per channel approach, but I can see where the 2 board per channel approach would be useful for other projects.

My 2 cents is that I wouldn't mind having more space on the board for caps in the signal path. Wima's are fine, but there is a whole world of caps out there (including quite a few in my workbench) and I personally don't mind if the board is a little bigger to make room.

Other thoughts?

Jac
 
Not sure if they have caught up with the thread, but jgf and Joel (Canada) were interested on page 7. That would be in the neighborhood of 24 to 32 boards. I'm in no rush, but that looks like it could be getting in the range where an order would be cost effective. How many did you have in mind for an order?
 
I just offered because billshurv wanted Jan's boards specifically. I'm not sure what the other folks want, and don't want to step on any toes. There's no minimum with the shop I use, so it's really about the economics of shipping and insurance as the tooling has already been paid for on my previous order.
 
Member
Joined 2014
Paid Member
Just to avoid confusion, as I'll be doing other things than phono with some boards I would also have a pair from Jackinnj when his next shipment of round tuits comes in. Not least that I can have a line stage as well in the nice case that used to contain a fairly rubbish counterpoint SA-1000 :)
 
Just for the record, I'm good with Jan's boards too. I'm probably getting over anxious, but I just ordered my first reasonably good cartridge and I just know that my current crap phono pre won't cut it.

Now we just need to make sure we aren't stepping on anyone's toes. How about SY and Jack, any issues with a little combined order of Jan's boards?

Jac
 
Not sure if they have caught up with the thread, but jgf and Joel (Canada) were interested on page 7. That would be in the neighborhood of 24 to 32 boards. I'm in no rush, but that looks like it could be getting in the range where an order would be cost effective. How many did you have in mind for an order?

I'm still in for enough boards for 1 or 2 preamps (depending on cost). Jan's boards look good to me.

Another thing, I see the diyaudio store has LSJ74 currently available in 2 of the 4 grades, are these acceptable? and which is preferred?

  • Grade C (Idss 10 - 20)
  • Grade D (Idss 20 - 30)
 
I'll get a fresh quote, but it came out to $5.88 per board on my last order of 24. I'll get a quote for another 24.
 

Attachments

  • IMG_20150419_120107.jpg
    IMG_20150419_120107.jpg
    872.7 KB · Views: 561
Last edited:
pFET?

Now that it looks like we are on the path to ordering some boards, I went back to the pFET discussion between jgf and SY. Looking on google and the usual suspects (Digikey, Mouser, Newark), there aren't any of the 2SJ108 alternative suggested by SY available commercially. In fact, the only available p-channel JFETs I could find are the Fairchild J176_D74Z which are an order of magnitude worse for noise.

So the choice appears to be the diyAudio store LSJ74 C spec with too much Idss or ebay for questionable 2SJ74. Price is about the same between the 'bay' and the 'store'. How do you guys weigh the C .vs. GR spec LSJ74 against the risks at ebay? How much trouble does that C spec introduce?

Jac

Correction. I did find a few pf the J271 at Mouser for a cheap price. The only other p-channel JFETs were more expensive than the LSJ74. I must be missing something here.
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.