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Part Sourcing Assistance/Advice Thread


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That would be nice if the bloody thing would fit in the chassis. 


Well they have a minimum order of 800$ so you cant' just buy one or two.  Shipping is on the astronomical scale and the transformers are cheaper but not a whole lot so when you set them strict requirements. 

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the cathode winding of opposite polarity is what mcintosh calls cross coupled cathodes.

A patent from the late 1950's. Definitely made a big difference in distortion. And they

did bifilar winding too. but otherwise standard steel with alternating E and I pieces.

There was a very recent youtube that showed them making transformers for the

reissue mc275.

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While we are complaining about vendors, a small warning about OSH Park:


For those who don't know, OSH park is a PCB manufacturer, er, aggregator/middle man. You upload PCB files to them and they send you 3 of your design in a few weeks. They have replaced BatchPCB basically.


For the most part, they have a lot going for them. The boards are reasonably high quality, the turn around time is not awful, and they are a neat purple color. And you can upload Eagle files directly without having to muck around with Gerbers. The downsides are that the turn around time is not really great, the purple is kind of ugly, and most importantly they are a little on the expensive side. For very small boards, it is a good deal, but once you hit 10 square inches or so, there are better deals out there.


If that were all of it, OSH would be a great resource for DIYers needing one off utility PCBs. And in most cases, it is. Here's the rub -- there is no way to contact them. If something goes wrong, you are out of luck. Case in point, 4 orders from them were supposed to be delivered to me last week. According to the post office, they were, but in reality, they weren't. I have talked to the post office which said there is nothing they can do. There was a temporary mail delivery person working that day. I tracked him down to ask if he'd help find the packages (he was still working yesterday) and he said no. Our regular mail delivery person was back today and said he'd help, but seemed doubtful of finding them. It is only $70, so not the end of the world. The bigger issue is the time which is frustrating.


Back to OSH, the issue is that I have tried to contact them to see if they can/will help, and there is no way to do it. I went to their support site and filed a question. They say they'll reply in 24 hours, but no such luck. I tried to escalate the issue, and it generated a new support ticket, referencing the original, which they have also not responded to. I sent an email to the only email address they publish, and this resulted in the automatic generation of yet another support ticket, which has also gone unanswered. So I assume I just suck it up. You get what you pay for, and sometimes not even that.

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Have you tried bay area circuits? I have been using my alumni email to snag one-off boards for ~$40 a pop. Don't think it's more expensive than that for non-edu holders. I bet it and sent off a kgst channel (they only guarantee one), got three boards. Quality isn't all there, but for a five day turnaround I'm not going to complain...too much

Edited by nopants
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Ask 5 transformer winders and you'll get 10 answers. Short answer is nickel (which is the same as mu-metal) will saturate quickly with DC requiring a larger core. The increased core undoes nearly all, or possibly more than all, of the benefit. Some people still like it, but you'll get less bass and less power for the same size. And it costs a fortune. There are likely better ways to spend your money. But if you really want to spend it on big cores, check out Lundahl.


For push pull it can work better. And push pull sounds better anyway. Slagle has experimented with adding a winding for filaments that is in the opposite direction as the main winding allowing currents to cancel. No idea how successful he's been.


For small signal stuff with no DC, nickel or amorphous or whatever is better that steel hands down. Where the dividing line is between small signal and large is the question.



Interesting. Less than an hour from me. Might be worth a trip down one of these days.

Thanks Doug.

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A transformer manufacturer?


I've emailed a few local ones here and they don't want to sell some to me unless I buy there toroids. I was hoping there was supplier somewhere or an ebay store that sell mounting plates standalone. Ah well. 

Edited by DefQon
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SumR didn't provide hardware for my latest order from them


I've only ordered once from SumR but there was no mounting hardware provided.  It was a fully encapsulated unit so there was a foam pad glued to the bottom and a nut shaped hole for a nut on top.  I ended up buying a M6 bolt, nut, washer, and locking washer from a local hardware store.  


Would any of these work for you: http://www.alphacoredirect.com/contents/en-us/d51.html

Edited by chiguy
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  • 3 weeks later...

Those pictures are fakes and dalbani knows it. Don't ever buy from them.


2sa1967 real things have the cutouts at the bottom of the transistors just like

the 2sa1967. Only difference is that the 2sa1967 has an exposed tab and

the 2sa1968 has plastic tab. I have some real ones, which I may dig out

later and take pictures of.

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  • 2 months later...

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