I am looking for a source for very small tube preamp transformers. I need to power a single 12AX7 so I would need around 220-250VDC at 5-10ma and 6.3V at 300ma
anyone know where i can find a small transformer like that? I can't seem to find anything that small.
Zc
anyone know where i can find a small transformer like that? I can't seem to find anything that small.
Zc
A Dynaco PAS transformer should be fine.
Somebody on ebay is selling a Dynaco FM3 transformer that should work.
https://www.tubes4hifi.com/Dynaco FM-3 manual.pdf
https://www.ebay.com/itm/394907818129
https://www.ebay.com/itm/296682007551
Somebody on ebay is selling a Dynaco FM3 transformer that should work.
https://www.tubes4hifi.com/Dynaco FM-3 manual.pdf
https://www.ebay.com/itm/394907818129
https://www.ebay.com/itm/296682007551
Not as convenient as a single transformer, but you could use a small isolation trans. with a voltage doubler for B+, and another small 6.3v filament trans.
jeff
https://www.ebay.de/itm/273852706118?_skw=r-+core&itmmeta=01JEZAZ1AMKSC2E8MG36S6HYHR&hash=item3fc2e4ad46:g:9DsAAOSwrLFc384K&itmprp=enc:AQAJAAAA4HoV3kP08IDx+KZ9MfhVJKnqLb85AezGP353Iqyc/3VnSWUUK/E2CWQBjb+pyurdDrqtxANXYOBR5bUXoYYCxzyCPFEQxxaI70vnAHTMKcEz66n/27z+C5UMVo31cIjLxFRiPI4YNBJJBpFFg6aN0odbFeexQFi4g/RrNXgytbKQQmssa/7x/vfNUBNXUhR/jkGM5QyZQnD/7E9/oQCMxkLEEQDyMSX8PULRih68SjV1Q2RHnaVDycJ+hettZEh9dTaK3ub2z9gscMtkAkmv5oBIH7/B7dkciCPsyi9cm97e|tkp:BFBM1pX86vdk
https://www.ebay.de/itm/255855823550?_skw=r-+core+tube+transformer&itmmeta=01JEZB17M8CBGTA1CN2JD47CV2&hash=item3b92320abe:g:lK0AAOSw7KFjiE~p&itmprp=enc:AQAJAAAA8HoV3kP08IDx+KZ9MfhVJKlHkmV8EFFN5ybV0sivBXhtSN5IAZkNncbxH62GDB++6NWrXuedj0vSQ+x3I+FOWo5SV0XEbQpdPZWSjfeR+jfqxehfvOc0Yyjipxrd9z0ZZDCuBxmlCERx1882relUjjT7gUgZ/5--i6sNBlW5vEmow46TGjKXIOmWuWxuiRgZRLbSypSQTGvyvUpEG2Fl0ZdM0ZGBaNugHE3T/HFo2aQ2T30zxtvN5fJD9HCvF7pdYYqbuzCWgfhlITWQi3LoYkDKQZpeaPvOHS68p23jYS9Z9tU2yltJMMztnDR8maax9g==|tkp:Bk9SR6T6hOv3ZA
https://www.aliexpress.us/item/1005005999380519.html?spm=a2g0o.productlist.main.19.3b0d2f40Nk4byf&algo_pvid=83040689-49df-4e39-a363-8caa71bdeb5e&algo_exp_id=83040689-49df-4e39-a363-8caa71bdeb5e-9&pdp_npi=4@dis!EUR!29.90!27.99!!!222.47!208.26!@21038df617340713363117335eaa17!12000035245637266!sea!DE!132128603!X&curPageLogUid=aAdTzoUYd7F4&utparam-url=scene:search|query_from:
https://www.ebay.co.uk/itm/126818993445?_skw=valve+amp+transformer&itmmeta=01JEZC54TNVJHMDP8HQTW08HQW&hash=item1d87004525:g:4CAAAOSwk25nVJrf&itmprp=enc:AQAJAAAA8Mxmj+iGvOveHXEBClPb29gGhkECSr9V8ArzgTbAkz1J4FcExUhirqf/IHR4hHgxiyLcbZU0x3GwhpvZkJ2PhbwHm9sB2737NS0mnOBglZjcOcaHQvOHZ5LwUuMvGdFB+lRAu0525gzBy+WrgXtnsZmaLVkEsK0nQ5enbvOtowvsXtdTAlrw322JvjPmFX4zPbKBOhs6GUhECwXpNI0A2DtZahix1NyT8epTCGplbPeipLlUUX/XjoZDppbBQVgMmydvQG9nu1uPC9/UUwLtlHonSM9jNa51qzHqLnWG6UubBsitSciFe8AiXTsY3s0jeg==|tkp:Bk9SR7DNlOz3ZA
You probably don't want the usual large(r) electrically oversized transformer but a 10 or 15VA one. These are harder to find compared to 30VA types but they exist. Various 10VA EI types with 170V and 6.3V secondaries exist. If you want old quality you will have to cannibalize old small tube devices. Sony had very small tube power supply transformers in gear. These are often in metal casing which is nice for audio.
If using cheap recent chinese stuff pay attention to what you buy and use correct fusing (well, always do that). You will look in vain for UL stamps and all the US electrical clubs approvals. Please look for 120V primaries. The R-core types are very silent and have very low stray field. Some chinese sellers offer custom winding so you can specify a 125V primary winding and 170V and 6.3V secondary windings in 15VA format. If you desire to regulate both voltages then take that into account.
If you decide on another tube type suitable for lower B+ you could use surplus left over custom toroid transformers as found on Ebay.
https://www.ebay.de/itm/255855823550?_skw=r-+core+tube+transformer&itmmeta=01JEZB17M8CBGTA1CN2JD47CV2&hash=item3b92320abe:g:lK0AAOSw7KFjiE~p&itmprp=enc:AQAJAAAA8HoV3kP08IDx+KZ9MfhVJKlHkmV8EFFN5ybV0sivBXhtSN5IAZkNncbxH62GDB++6NWrXuedj0vSQ+x3I+FOWo5SV0XEbQpdPZWSjfeR+jfqxehfvOc0Yyjipxrd9z0ZZDCuBxmlCERx1882relUjjT7gUgZ/5--i6sNBlW5vEmow46TGjKXIOmWuWxuiRgZRLbSypSQTGvyvUpEG2Fl0ZdM0ZGBaNugHE3T/HFo2aQ2T30zxtvN5fJD9HCvF7pdYYqbuzCWgfhlITWQi3LoYkDKQZpeaPvOHS68p23jYS9Z9tU2yltJMMztnDR8maax9g==|tkp:Bk9SR6T6hOv3ZA
https://www.aliexpress.us/item/1005005999380519.html?spm=a2g0o.productlist.main.19.3b0d2f40Nk4byf&algo_pvid=83040689-49df-4e39-a363-8caa71bdeb5e&algo_exp_id=83040689-49df-4e39-a363-8caa71bdeb5e-9&pdp_npi=4@dis!EUR!29.90!27.99!!!222.47!208.26!@21038df617340713363117335eaa17!12000035245637266!sea!DE!132128603!X&curPageLogUid=aAdTzoUYd7F4&utparam-url=scene:search|query_from:
https://www.ebay.co.uk/itm/126818993445?_skw=valve+amp+transformer&itmmeta=01JEZC54TNVJHMDP8HQTW08HQW&hash=item1d87004525:g:4CAAAOSwk25nVJrf&itmprp=enc:AQAJAAAA8Mxmj+iGvOveHXEBClPb29gGhkECSr9V8ArzgTbAkz1J4FcExUhirqf/IHR4hHgxiyLcbZU0x3GwhpvZkJ2PhbwHm9sB2737NS0mnOBglZjcOcaHQvOHZ5LwUuMvGdFB+lRAu0525gzBy+WrgXtnsZmaLVkEsK0nQ5enbvOtowvsXtdTAlrw322JvjPmFX4zPbKBOhs6GUhECwXpNI0A2DtZahix1NyT8epTCGplbPeipLlUUX/XjoZDppbBQVgMmydvQG9nu1uPC9/UUwLtlHonSM9jNa51qzHqLnWG6UubBsitSciFe8AiXTsY3s0jeg==|tkp:Bk9SR7DNlOz3ZA
You probably don't want the usual large(r) electrically oversized transformer but a 10 or 15VA one. These are harder to find compared to 30VA types but they exist. Various 10VA EI types with 170V and 6.3V secondaries exist. If you want old quality you will have to cannibalize old small tube devices. Sony had very small tube power supply transformers in gear. These are often in metal casing which is nice for audio.
If using cheap recent chinese stuff pay attention to what you buy and use correct fusing (well, always do that). You will look in vain for UL stamps and all the US electrical clubs approvals. Please look for 120V primaries. The R-core types are very silent and have very low stray field. Some chinese sellers offer custom winding so you can specify a 125V primary winding and 170V and 6.3V secondary windings in 15VA format. If you desire to regulate both voltages then take that into account.
If you decide on another tube type suitable for lower B+ you could use surplus left over custom toroid transformers as found on Ebay.
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😎 It's almost as if it was made to order! I was looking for a similar one of these myself that would be a little thinner than an Antek.
https://www.hammfg.com/electronics/transformers/classic/261-262
With a voltage doubler for B+ and 6.3V filament, the 7VA 262B6.
With a voltage doubler for B+ and 6.3V filament, the 7VA 262B6.
Good find and a good brand but the 262EE6 could be a better choice as it has 120V primaries. With mains voltage only going up..... Will deliver about 170V unregulated DC B+ (Graetz bridge diode rectification).
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If you want to go really cheap you can use one from a shaver socket for HV, and a 12V smps for the 12AX7.
Most of these options are just too big in physical size not to mention way more power then i need.
I looked at these and the 261 i might be able to make fit. but i would have to add a couple of resistors to drop the voltage down a little bit. or the 262B6 but then i would have to add diodes and caps for a voltage doubler. both MIGHT work.
Is aliexpress a legit site to buy from?? i have never bought from there. seemed sketchy so i wasn't sure.
I do buy from mouser, digikey, for capacitors, semiconductors, Hammond etc. Yes, they are more reliable. But power transformer's prices have gone through the roof, and I find that I can get good quality ones from Aliexpress, never had an issue with them. The rules: always over spec things. Aliexpress watts are like RMS vs Peak, just divide by 1.4. Read the descriptions very carefully, and you may save plenty of money. Or, just go for the established distributors and save the hassle.
I love some of the descriptions in Aliexpress (this one for a pre-amp SMPS):
...
Quiet as a virgin, active as a rabbit, with a clean bottom noise. The high pitched sound is clear, while the mid pitched sound is rounded, which solves the problem of the original electronic tube lacking low pitched sound and makes your machine's low pitched sound more powerful.
...
Also be ready to deal with cows, bile, cattle when reading transformer descriptions.
I love some of the descriptions in Aliexpress (this one for a pre-amp SMPS):
...
Quiet as a virgin, active as a rabbit, with a clean bottom noise. The high pitched sound is clear, while the mid pitched sound is rounded, which solves the problem of the original electronic tube lacking low pitched sound and makes your machine's low pitched sound more powerful.
...
Also be ready to deal with cows, bile, cattle when reading transformer descriptions.
@jcalvarez.
yeah you forgot to float like a butterfly and sting like a bee..
where are you going with virgins the bile and the cattles? We're buying transformers here, right? 🤣
yeah you forgot to float like a butterfly and sting like a bee..
where are you going with virgins the bile and the cattles? We're buying transformers here, right? 🤣
That's a funny way of putting it. I 'support' them as much as I support Sinclair gas station when I am on my skiing trip and find myself in between Ogallala NE and Denver CO and I am at 15% in the tank.
Check into who owns them and hope they never take the business in a different direction or there will go your diyaudio hobby..
