Came across this company/seller - https://www.ebay.co.uk/sch/i.html?_...wersupplies&_oac=1&_trksid=p2047675.m3561.l25 the other day and haven't noticed it discussed on the forum, the OPTs look ok and at a good price. Not much good for those of us this side of the pond but maybe one to bookmark.
Andy.
Andy.
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I've seen those, yes, they are well priced. But, as you said, delivery an import duties kill the thing for us in the UK.
I got some OPT's from Musical Power Supplies back when he was in Florida. They were good for the price I paid, but I don't think that he uses the same supplier today. The OPT's I got were made in one of the Caribbean islands.
The last two pairs of OPT's that I purchased were from Toroidy in Poland. Even with FEDEX shipping to the US they were reasonable, and they sound better than anything in a comparable price range.
The last two pairs of OPT's that I purchased were from Toroidy in Poland. Even with FEDEX shipping to the US they were reasonable, and they sound better than anything in a comparable price range.
+1 for both of those suppliers. Musical is now in Tennessee and has a lot more offerings now. I've been pleased with his stuff.
Toroidy shipping, at least for the USA, is a flat $9.95 up to a point, i.e. one transformer per order otherwise it goes past the $9.95 weight limit and balloons way up.
Toroidy shipping, at least for the USA, is a flat $9.95 up to a point, i.e. one transformer per order otherwise it goes past the $9.95 weight limit and balloons way up.
I’ve had good luck with OPT from HifiEquis on AliExpress. Shipping is high but the transformers are well made and well priced. It only took two weeks to arrive in the US. I got a pair of 30 watt SE outputs for like $210 delivered and they sound great! They have PP Opts too. I have no affiliation but I’m happy with what I got. I’ve used threes sets of different units from them. They have smaller units for much cheaper too.
He does make some hifi units, most of these are for guitar amp use and likely don't have a great frequency response curve. I'm not sure if it was spam filter issues, but I've never been an email response from them.
I did message Matt with some success, I sent him some specs from Edcor to see if he had something similar. But as Stephe mentioned, most are designed for guitar amps, but he has hifi ones too, just need to msg him, and he replies within 48hrs. I wouldn't mind Edcor if their shipping wasn't so expensive. What other ones besides the typical (Edcor, Hammond, Traid) does everyone use here in the US?
Sadly, Transcendar and Electra-print are out of business. Hayboer is a good transformer builder at not outrageous prices. I’m using some Hayboer units in a PSE amp I’m building and haven’t heard them yet but they are well made. Edcor takes forever to build and ship anything, like months not weeks!
I now just buy Hammond OPT's and mount them underneath the chassis. Read the data sheet carefully and you will see they are rated at full power for frequency response unlike Edcor which does not specify at what power they measure their frequency response. At real world listening levels they have excellent bass response. Pay attention to the to the graphs on the data sheet and not their printed frequency response. I do wish bell caps were available though where they would look better if mounted on top of the chassis.
+1 for Toroidy, as @tomlang says. If you buy from TNE.com they are very reasonably priced AND they ship them in ~5 business days to USA (I received some 3 months ago) at $9.95 per shipment (if under 5 kg). So, typically buy and pay shipping one at a time for the larger transformers.
Heyboer makes nice transformers. Their Peerless S-265-Q copy is excellent. I actually prefer them to the originals in my Williamson amplifiers. But at 10K p-p their utility is limited. I also have some 5K 30 watt push-pull models (HTS-9293) I bought from an eBay seller a while back. I tried them in a triode-wired EL34 amp I was working on, and they measured nicely:
It's worth calling Heyboer to see what they have ready-made, or at least designs in the files. They're not as cheap as Hammonds but they aren't that much more, either. The Peerless copies are a steal at $250 each.
It's worth calling Heyboer to see what they have ready-made, or at least designs in the files. They're not as cheap as Hammonds but they aren't that much more, either. The Peerless copies are a steal at $250 each.
Grover,
Thanks for posting the square-wave response and response bode plot. That HTS-9293 performed well! We see to few plots of the sort.
Do you mind briefly explaining what you used and how you did the response plot?
Thanks for posting the square-wave response and response bode plot. That HTS-9293 performed well! We see to few plots of the sort.
Do you mind briefly explaining what you used and how you did the response plot?
It's TME.com
https://www.tme.com/us/en-us/katalog/toroidal-transformers_100028/?mapped_params=2:1081;444:1492004;
I have a large stash (100+) of new "A-495" 6600 ohm to 0-4-8-16 ohm OPT's still in 8 piece bulk pack boxes that were made by Schumaker in Chicago for the ADA guitar amp company, who disappeared before they were delivered. These work well at 80 watts or more in guitar amp applications, and at 40 to 60 watts in HiFi applications. I will be listing them in the swap meet here, along with a lot of other surplus stuff from Tubelab Inc. which will likely cease operations at the end of 2023.
The amp is a standard Williamson design that normally uses the UTC LS-57 so I was interested in comparing the two. I actually used a pretty steep step filter at the input, since the UTC has a lot of HF energy, so I might try it again with less filtering and see how it looks with more HF extension. I use a Picoscope and there's a third-party app that let's you run a Bode plot. It will also display gain margins, phase margins and phase shifts.