DIY talk

Discussion in 'DIY' started by Cspirou, Jul 25, 2021.

  1. Cspirou

    Cspirou They call me Sparky

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    @Garns
    This post looks like what you want

    https://www.tubecad.com/2019/04/blog0461.htm

    Screen Shot 2021-11-21 at 10.25.43.png

    Also according to this post it seems like parallel transformers is fine for tubes.

    https://www.tubecad.com/2005/March/blog0041.htm

    So It can be done but with all the iron seems like more of a monobloc situation with perhaps dual subs.

    Also I read to directly drive a passive sub he has suggested to use a toroidal power transformer since they are big and meant to operate at 50/60Hz just fine and will filter out higher frequencies.
     
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    Last edited: Nov 21, 2021
  2. ogodei

    ogodei Headphone Heaven Gatekeeper

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    Last edited: Nov 21, 2021
  3. Pancakes

    Pancakes Friend

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    Really??? That's incredibly useful for those orders when the parts cost less than the shipping. What's a checkbook lol?
     
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  4. Biodegraded

    Biodegraded Friend

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    (Digs in drawers) Yes! With 3 cheques left!

    Edit: Maybe not for Canada. The info on the forms is conflicting, the US form saying shipping & insurance to US & Canada addresses is free, but the Canada form saying $8 CAD shipping for orders under $200 (for online orders, Canada shipping is free over $100).

    I guess somebody in Canada could try it using the US form to see what happens...
     
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  5. ogodei

    ogodei Headphone Heaven Gatekeeper

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    I think the Canadian form just doesn't include the information. Their terms and conditions online says its for both US and CA

    Sec II, para 6: "When a check or money order accompanies your order, Digi-Key pays all shipping and insurance (our choice for method of shipping) to all addresses in the U.S. and Canada."

    https://www.digikey.com/en/terms-and-conditions
     
  6. Biodegraded

    Biodegraded Friend

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    It's different at the Canada site, https://www.digikey.ca/en/terms-and-conditions . There's a para 7 that starts, "Click here to see if your purchase qualifies for free shipping." That takes you to https://www.digikey.ca/en/resources/local-support , which states $CAD8 shipping if under $CAD100.

    Looks like they need to update the stuff at the .com site to eliminate the Canada references.
     
  7. Beefy

    Beefy Almost "Made"

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    Digikey shipping really is an absolute bargain for Canadians. I've placed an emergency order in the evening, and had it the next morning. For $8! Fighting for free shipping seems entirely redundant.
     
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  8. Biodegraded

    Biodegraded Friend

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    I recently placed a >$100 order (free Fedex International Priority) from them in the afternoon and it was here in Vancouver late the next morning. Their warehouse is so close to the Manitoba border they probably just walk out the door and throw the boxes over; I imagine you guys in Winnipeg getting morning orders by lunchtime. It might help that the local CBSA office is a training centre - the processing agents are probably young and eager to impress.

    I've had fast deliveries on the $8 scheme too. But when all I need is a couple of small things I can't find locally, $8 still feels like a couple of beer I could have had instead...

    Expanding the discussion a bit: because of the fast delivery into Canada, I look at Digikey before Mouser (Mouser has an Ontario address, but everything seems to come from Texas). But component prices can be different between the two houses. In a recent shop for the part set for the Whammy amp, Mouser prices mostly came in cheaper than Digikey. Is that usual, in people's experiences?

    Edit: Mouser shipping to Canada has the same price terms as Digikey: $8 up to $100, free above that. Mouser uses UPS for the >$100 shipping - which took a day longer from TX to me than from Digikey in MN - but USPS/CP for the $8 plan, whereas Digikey uses Fedex for both.
     
    Last edited: Nov 21, 2021
  9. Beefy

    Beefy Almost "Made"

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    Yep, Mouser a smidge cheaper than Digikey for most things. A bit of a bias towards small components being cheaper at Mouser, larger/bulkier and hardware items (e.g., IEC inlets) cheaper at Digikey.

    I normally build a shopping list at both, and delete the item from whichever supplier is more expensive. Usually end up 40% of my money at Digikey, 60% Mouser. But Digikey makes it back because I frequently do small under $100 orders at Digikey because of the $8 shipping, never do under $100 at Mouser ($20 shipping).
     
  10. Cspirou

    Cspirou They call me Sparky

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  11. peef

    peef Friend

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    It's only crazy if you're hoping to save money. :)

    It is however difficult to overstate just how difficult it is to get high quality, bass limited transformers. I did a first round with Electra-Print, and they optimized it by taking a very large core (1.25" x 2" lam stack, or about 3" x 4" x 4" overall, for 20W) to keep inductance up with very few turns of wire (resulting in a very low window fill). It works, but it is not free, and looks sort of dumb. The sample I got was made was spec'd with a 1.2k primary and had a primary inductance of 5H. None of this made sense, so I gave up and put it in a guitar amp instead. Here's what it looks like.

    [​IMG]

    Another option is to try the same transformer for low and high duties, and adjust the gap to trade inductance for linearity. If you hate money, Intact does this. If you ask Cinemag nicely, they can sometimes provide the lams and bobbins separately, allowing you to regap the transformers or change the interleave of the lam stack.

    Yet another, safer option is to get the same bobbin on different core materials. Silicon steel is more difficult to saturate than an amorphous core, but has a lower permeability. I'm futzing with an active 2.5 way with amorphous Lundahls on the tweeter and midwoofer, but regular steel on the bottom .5 woofer, and am very pleased with it. But then I'm certainly not about to go out and buy an extra set of steel cores to A/B. :)


    I think the opposite is true-- they used to be popular on diyA in parafeed amps since they have a very usable bandwidth. EI-core, and especially split bobbin transformers tend to offer lesser coupling at high frequencies.
     
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  12. Armaegis

    Armaegis Friend

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    Though for this same reason we can also get slapped here with a lot of import fees on stuff entering the country. I've almost given up entirely on ordering from outside Canada unless the shipper has an all-inclusive shipping option.
     
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  13. Garns

    Garns Friend

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    Thanks! This isn't really about trying to save money, in fact it's really more a thought experiment for an imaginary life where I have a job where I bark down phones with my head in my hands and look incredibly stressed and try to forget about my ulcer by sourcing increasingly exotic transformers. But I see your point! I did turn up that Thomas Mayer had built something like this (part 1, part 2) using a Tango transformer (M757).
     
  14. Cspirou

    Cspirou They call me Sparky

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    A little tip. If you have a PCB for a project you should get all the components as well even if you don't plan building right away. Manufacturers stop making parts all the time and by the time you do decide to make it, you might be screwed.

    You could always sell it as an unassembled kit later
     
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