Wiener group buy #2 - Stereo and PBTL editions available!

[jigglebones]

I think just a handful of us built with input transformers. These amps sound great with/without them. I wanted to take things all the way for my little nearfield setup. It's an expensive way to gain a little something, at least if you go the CineMag route. You could leave room for them and then add later if you got curious. Really they just allow you to bypass the input cap, get a pseudo differential input and perhaps add some coloration due to non linearity.

BK

That clears things up greatly, thanks! The Jensens are 75 bucks (!!!)a piece on PE so I think its a safe assumption the cinemags are significantly more. As the saying goes "if you have to ask, you can't afford it".

 

[gmarsh]

Big advantage of the Cinemags is they provide really good ground isolation.

I've exposed the differential inputs of the TPA on the Wiener card, unfortunately the chip can't handle much common mode offset at all which means you can't really float the RCA inputs. You can with Cinemags.

 

[gmarsh]

So I think the 3 card order has fallen through.

Right now, I've got 2 cards unclaimed, and mb/steveeboy/jigglebones (3 people) showing interest. I haven't heard from anyone who hasn't got their card yet, though I'm sending international airmail so it might be a few weeks.

Waiting for the Coilcraft order to come in right now for lostthumb's PBTL build. Just designed one of their camera flash charging transformers into a 5V->200V converter for a Nixie clock design I'm working on.

 

[irribeo]

Any offset would become 2nd harmonic distortion correct ?

 

[gmarsh]

Probably "every possible harmonic plus intermodulation" distortion if the input stage clips. The input voltage range of the INxx pins is 0.3V to 6.3V in the absolute max table, practically less than that.

I exposed the differential inputs to allow differential sources to be used, and to prevent creating ground loops when you're wiring together these cards and other cards (preamps, MiniDSP cards, whatever) in the same box where everything's grounded together anyway through power supplies and/or the chassis. They're not suitable for receiving RCA inputs from a different box directly; the RCA ground and power ground should always be connected in this case.

 

[jigglebones]

They're not suitable for receiving RCA inputs from a different box directly; the RCA ground and power ground should always be connected in this case.

RCA ground and power ground would be the shield/outside portion of the rca jack, and the (-/black) power cable, right? Are you still doing the chassis mount kit still? Having that would make this first time build more painless. I've been looking at that small Sure project box, its appealing for me due to having all the holes for terminals pre-cut but the case is like an aluminum tube, and doesnt look like it will split, how do you screw anything in there? are you supposed to fix the board to the rear plate with some kind of L-shaped bracket, and slide the whole thing in?

 

[irribeo]

You keep talking about RCA inputs, why ?

 

[mb]

@gmarsh, for your planning purposes: I'll take a 6 ohm board if/when it becomes available. I've checked the impedance curve for the target speaker to be used with the Wiener, and while nominally 8 ohms, it dips to around 6.5 ohms. Thanks.

 

[gmarsh]

So, just got paid for the "3 Wiener" order! group buy #3 is officially on the go.

So far 5 people have expressed interest:

atoluma: 3 (paid)
jigglebones: 1
mb: 1

Ideally this would hit 10 so I can get qty 10 prices on parts and make this at least half worthwhile doing Post if y'all are interested.

 

[steveeboy]

oh, I am interested for sure! if this is for complete cards, cannot do SMD.

or, if there is an unclaimed built out stereo or dual pbtl set up I would be interested in that as well.

But if you are looking for numbers for group buy, definitely count me in for one completed stereo card.

--AND FINISH THE CAMP!!!

 

[gmarsh]

cAMP hardware is finished and built - just a matter of final software tweaks if any are needed, programming production cards, packaging and shipping. That's in Canopy's hands, and viktor89 is in engineering exam week right now. So soon, I hope...

Fire me a PM with the load impedance you want.

 

[bruce potter]

Put me down for another fully assembled 8 ohm board please.

 

[dlucy67]

I'm just now learning about all this and I'm interested in trying out a TPA amp. My application would be simple stereo inputs and 8 ohm outputs. Will this new order fit those parameters? If so, count me in.

What is the cAMP you guys keep talking about?

 

[eplates]

If your doing another group buy on the fully assembled stereo card..would like 1 8 ohm .... Just let me know when your ready

 

[gmarsh]

OK, been a busy few days here but I'm finally getting back on this.

List of orders/interest:

atoluma: 3 x 4 ohm (paid)
jigglebones: 1 x 6 ohm (paid)
steeveboy: 1 x 6 ohm + mounting kit (paid)
mb: 1 x 6 ohm
bruce potter: 1 x 8 ohm
dlucy: 1 x 8 ohm
eplates: 1 x 8 ohm

Lostthumb, haven't forgotten about ya, my Coilcraft order should be in tomorrow to finish your PBTL cards.

I have four thermal pads left, steeveboy has claimed one of them, 3 remain - $10 CAD for a mounting kit with a pad, spacers, screws/nuts/etc. Since all inductors are back in stock at Mouser, I'll bring back filter kits if anyone wants (full set of parts for 4/6/8 ohm operation), cost is now $15 CAD due to the canadian dollar sucking and driving up the cost of parts.

mb, I'll fire you a PM in a sec with my paypal info. Anyone else, PM me with exactly what you want and I'll fire back my Paypal info.

Thanks!

 

[atoluma]

I have order 3 mounting kit too I think

 

[dlucy67]

gmarsh,

I've sent you a PM.

thanks,
dlucy

 

[eplates]

Pay sent

 

[gmarsh]

Here's the current list:

atoluma: 3 x 4 ohm (paid)
jigglebones: 1 x 6 ohm + mounting kit (paid)
steeveboy: 1 x 6 ohm + mounting kit (paid)
mb: 1 x 6 ohm (paid) + mounting kit is yours if you want it, just sent you a PM
eplates: 1 x 8 ohm (paid)
bruce potter: 1 x 8 ohm + mounting kit (just PM'ed you)

All mounting kits are accounted for now.

Coilcraft order came in yesterday so I should have lostthumb's order out before NYE.

 

[atoluma]

Hi Gmarsh,

I order 3 mounting kit too!