I am starting a ribbon mic project build. Since it's my first build, I don't want to invest much money into it. I'm having a hard time finding a low-cost transformer? The cheapest, after shipping, seems to be in the $40-$50 USD range, but I'd like to get cheaper, even at the cost of quality. I figure I can always upgrade.
Can anyone recommend a good source for something around a 1:37 ratio?
Thanks
Can anyone recommend a good source for something around a 1:37 ratio?
Thanks
120VAC : 6.3VAC CT power transformer, half the secondary, makes 38:1
Bass response may be OK since the ribbon should be far below nominal heater impedance. Treble may range from eh? to awful depending on winding configuration. The old Signal 241 had secondary tight over primary and ran past 15kHz. But a twin-bobbin I tried barely made 400Hz.
Shielding is a BIG deal.
Forty bucks is incredibly cheap.
Bass response may be OK since the ribbon should be far below nominal heater impedance. Treble may range from eh? to awful depending on winding configuration. The old Signal 241 had secondary tight over primary and ran past 15kHz. But a twin-bobbin I tried barely made 400Hz.
Shielding is a BIG deal.
Forty bucks is incredibly cheap.
Well, I thought I had a power transformer in my junk bins, but no luck. So, I'm still looking for a super cheap step-up if anyone has any ideas. Thanks again
Wind it yourself on a ferrite core set. Mind you, the magnet wire might blow your budget if you can't get it on, say, 50g reels.
Something in the region of PQ2620 might be a good place to start : https://www.aliexpress.us/item/3256803520736842.html?spm=a2g0o.productlist.0.0.14a41f1aAamk5t&algo_pvid=a40d3d33-1bb3-4632-8d91-71f878112448&algo_exp_id=a40d3d33-1bb3-4632-8d91-71f878112448-0&pdp_ext_f={"sku_id":"12000026878771329"}&pdp_npi=2@dis!USD!2.68!2.68!!!!!@2132a21016698174959816542e8b39!12000026878771329!sea&curPageLogUid=P7Je7qOF72JX
To give you some idea of how many turns, for a peak primary voltage of 0.1V its 20 turns. Then your secondary will be 740 turns. Probably want to interleave the windings to reduce the leakage inductance.
Something in the region of PQ2620 might be a good place to start : https://www.aliexpress.us/item/3256803520736842.html?spm=a2g0o.productlist.0.0.14a41f1aAamk5t&algo_pvid=a40d3d33-1bb3-4632-8d91-71f878112448&algo_exp_id=a40d3d33-1bb3-4632-8d91-71f878112448-0&pdp_ext_f={"sku_id":"12000026878771329"}&pdp_npi=2@dis!USD!2.68!2.68!!!!!@2132a21016698174959816542e8b39!12000026878771329!sea&curPageLogUid=P7Je7qOF72JX
To give you some idea of how many turns, for a peak primary voltage of 0.1V its 20 turns. Then your secondary will be 740 turns. Probably want to interleave the windings to reduce the leakage inductance.
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Hi! Is ferrite good enough for bass?
I bought some spare SM58 transformers on Ali that are little bigger than originals. They are 1:4 step up. Is that a suitable core for winding ribbon mic transformer? And what would be number of primary turns? Sadly I have no idea are there any nickel in core material.
And in general, are those cores good for other transformers such as microphone 1:7 or 1:10 ??
I'm not quite sure what you mean 'is ferrite good enough for bass?'. Sure it can pass bass signals but wouldn't be very practical as an OPT which needed to handle bass.
As to your trafos from Ali, I couldn't answer without details of the core material used, dimensions etc.
As to your trafos from Ali, I couldn't answer without details of the core material used, dimensions etc.
I ment, is power ferrite even any good for audio transformers? I red somwhere that is not, only iron/silicon/nickel alloys are for audio.. etc.
Anyway is there something that I can measure about my transformers that would tell you more about them? I measured core cross sect. area 0.36cm2. and I know its 1:4.
Anyway is there something that I can measure about my transformers that would tell you more about them? I measured core cross sect. area 0.36cm2. and I know its 1:4.
For audio signal transformers I find ferrite is acceptable. I'd not use it for full range in a power application - in an output transformer for example, but its fine just to feed a tweeter where the lowest frequency is 1kHz or so.
Those materials are generally superior to ferrite as they usually support higher maximum flux. Ferrite's advantage is its ease of DIYing and its low price.
The mechanical dimensions are one thing but the max flux of the material isn't something that's easily measured. If you're curious about making your own signal transformers I opened a thread to give some assistance here : https://www.diyaudio.com/community/...-input-transformer-step-by-step-guide.292658/ This guide isn't comprehensive enough to cover step-up trafos though.
Just a thought, but nanocrystaline cores (sometimes called Metglas) have become relatively easy to come by in the last few years, are stocked by distributors like Mouser and Digikey, and the prices have come down a lot. It might not be all that difficult to achieve reasonable frequency response this way, since it's got both very high permeability, low losses at HF, and very high saturation flux. Never bothered to look at the linearity, but I would expect it to be pretty decent.
That said... the signals here are so tiny that you probably won't run into any saturation issues with ferrite, even at pretty low frequencies.
That said... the signals here are so tiny that you probably won't run into any saturation issues with ferrite, even at pretty low frequencies.
Here's Mouser's cheapest offering of a Metglas core : https://www.mouser.com/ProductDetail/Proterial/AMCC0004 : $24 a set. For some reason they're classified under 'ferrites'.
Great! I will check it out
Do you have any expirience winding on nanocrystal torroids? I have some, around 25mm and smaller. This core you found is great, too bad shipping price kills..
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Very little experience of winding toroids, the ones I have wound have been inductors on Sendust and powdered iron cores. Winding toroids by hand is extremely labour-intensive.
Having a core is one thing, you'll also need a suitable bobbin and they're often hard to find. If you get the right sized C shaped cores you can use two side by side in an EE type bobbin intended for ferrite cores.
Having a core is one thing, you'll also need a suitable bobbin and they're often hard to find. If you get the right sized C shaped cores you can use two side by side in an EE type bobbin intended for ferrite cores.
True. Thats the reason I never did anything with them but I saw on YT video a guy wounded maybe total of 150 winds on green toroid, the one from AC line filters and got sound from it. Maybe I will do it but on my nanocry. toroid.
I have 3d printer and 3d print bobbins, use SolidWorks to draw it and directly print it. 🙂 If you dont have 3d printer, at least here there are many that will print your project for some acceptable fee. There are even finished 3d bobbins online but I didnt need them.
Has anyone ever tried transformers as used in these 5$ - electrical mosquito-killer racket inverters?
That guy's website I visit a lot for his noise measurements on transistors so I'm guessing its an excellent calculator. Just one point I noticed - if you're designing with ferrite he's taken the core temperature to be 100oC but that'll be very pessimistic in an audio application. The max B decreases with temperature so at 25oC it'll handle a bit more flux than at 100oC.