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Rolled the dice on Chinese OPTs

Choosing the final parts I need to order for my SSE and working out pricing for various OPT options. One thing that really makes a difference is shipping charges.

I stumbled upon some relatively ugly 5k into 4/8ohm OPTs on ebay from China. They are described as "8-10 watt" and the specs match up approximately with the Transcendar 7 watt units and they are close to the same size as the Edcor XSE 15 watt units but the Chinese ones have a considerably thicker stack (35mm vs. 27.7mm). I have determined that 4-5 watts is about all I need 95% of the time.

I've made an offer on them and if it is accepted I will end up with two of them for $60 CAD including shipping. For comparison, the Edcors would be more like $130 CAD including shipping.

Believe me when I say, I do not have any expectations whatsoever about these OPTs. I know George stated on his site that people are unlikely to upgrade OPTs so they should buy what they really want the first time. Well, if these OPTs are crap, I will have no qualms about pulling them and upgrading to Transcendars.

This is basically just an experiment, with the benefit that it will expedite my ability to build and bench-test my amp. I'll update this thread when I have some experience with the OPTs.
 
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Looking forward. I am in the process of deciding to order a pair of SE opt, 3watt. Specs says 20hz- 20khz. I found them in AliExpress. Any inputs will be helpful.since, even the cheapest OTP from china costs huge money to India,with shipping. And to import OTPs like Hammond,costs thrice that

I found those units on AliExpress that you are talking about. The price is right, that is for sure. They might be satisfactory for very light "easy listening". The reviews seem okay. Best of luck.
 
The seller countered my offer, and this has given me a chance to reconsider. It is going to cost me about $75 CAD to get these OPTs. It has occurred to me that it is almost certainly wiser to just spend the money on Transcendars, if I think that's what I really want. After all, I have chosen high quality components and will be installing a choke, supplementary cap, etc. so why cheap out on the OPTs (the most important component)?

In the back of my mind I am telling myself that I could always use the Chinese OPTs for a more basic, budget SSE build. If that is the intent right from the start, I might as well wait and buy them if I decide to build a budget SSE.

I have a bit of time before I accept the counter-offer. I suspect I am going to let the window pass, but I can't quite get myself to forget that the Transcendars are going to increase overall amp cost by between $175 CAD (7w) and $240 (10w) over the Chinese OPTs.
 
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The seller countered has given me a chance to reconsider. $75 CAD for these OPTs.

Just consider that in China, the cost of grain-aligned ferro-silicon sheet is about $0.75/lb, and the cost of high purity magnet copper wire is about $3.50/lb, high-T enameled. (I have a friend who answers these kinds of questions from Shanghai).

Your basic 10 W Edcor clone is going to weigh about 3.5 lbs. So… 50:50 copper-iron is
(Cu: 1.75 lb • $3.50) ⊕ (SiFe: 1.75 lb • $0.75) = $7.47 in materials​
And they want you to pay $75 for each? Even if it is $75 Canadian, (at $1.32 CAD → $1.00 USD), that's still $56.80 USD.

Which is 7.5× over-materials.
What's the cost of the shipping?

If included, then it may not be that weak of a deal!
If seperate, then its just getting usurious.

⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
⋅-=≡ GoatGuy ✓ ≡=-⋅
 
Just consider that in China, the cost of grain-aligned ferro-silicon sheet is about $0.75/lb, and the cost of high purity magnet copper wire is about $3.50/lb, high-T enameled. (I have a friend who answers these kinds of questions from Shanghai).

Your basic 10 W Edcor clone is going to weigh about 3.5 lbs. So… 50:50 copper-iron is
(Cu: 1.75 lb • $3.50) ⊕ (SiFe: 1.75 lb • $0.75) = $7.47 in materials​
And they want you to pay $75 for each? Even if it is $75 Canadian, (at $1.32 CAD → $1.00 USD), that's still $56.80 USD.

Which is 7.5× over-materials.
What's the cost of the shipping?

If included, then it may not be that weak of a deal!
If seperate, then its just getting usurious.

⋅-⋅-⋅ Just saying, ⋅-⋅-⋅
⋅-=≡ GoatGuy ✓ ≡=-⋅

$75 CAD (US $58.00) for both (not each), including shipping. To be clear, I would pay $75, total, and 2 OPTs would land on my doorstep a few weeks (months?) later.

Can you see why I am tempted to just get them, even if I know I am probably going to buy Transcendars some day?

They claim Japan imported z11 sheet and oxygen-free copper (however primary resistance is "about 400ohms"). "Power: 8-10W (20Hz)"
 
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I just renewed my truck insurance and discovered that my annual premium dropped by over $1100 per year, so I said feck it and accepted the offer to buy these OPTs. Actual cost came to a total $79.39 CAD after conversion and whatever Paypal fees (?).

Like I said, I am probably going to buy some Transcendars anyway, but I am just too curious about these Chinese ones at this crazy price. Time will tell - can't back out now! :)
 
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Good luck.
As you confirmed the combined price, including shipping is quite attractive.

IF they did a reasonably “good job” spinning the windings and securing the taps, then you ought to have a decent transformer pair. Out of curiosity, how much is the shipping weight?

The answer says a lot as to whether “enough materials” were used.

⋅-=≡ GoatGuy ✓ ≡=-⋅
 
Good luck.

Thanks. It's no big loss if they are rubbish.

Out of curiosity, how much is the shipping weight?

The answer says a lot as to whether “enough materials” were used.

No weight is listed in the description, which says a lot without saying anything. It does make me suspicious. I will have no more details until they arrive. At that point I will weigh them and report back.

I'm sort of "taking one for the team" here. If they are crap - oh well. If they are decent, then perhaps others here will feel like giving them a try.
 
This is the second time I've heard Transcendar referenced in the last week. Is he back to winding transformers? About 1.5 years ago when I contacted him he wasn't taking orders and I assumed he was retiring from the business.

Gery's site is running and he responded to my e-mail query promptly. He included a price list.

So yep, he's winding!
 

tubebob

Member
2020-03-29 8:00 pm
Transcendar

I tried those 5K transformers. Paid 17.95 each from Amazon. I used them to test things out while building and waiting... I ordered set of transformers from Gery at Transcendar (which just arrived to replace them). They definitely sound better. They cheap ones were however better than I expected. The specs state 35-20 frequency response. I think they played lower than a set of similar Edcors I have around.
 
Based on these glowing recommendations, I ordered one of these transformers from Amazon.

The specs say it all "Maximum Power Per Channel: Above 200W"...."Winding method; 3+2 fever grade winding."

Two hundred watts through a transformer that weighs about 1 pound, yeah right! Fever grade.....these transformers come with the virus baked in.

With all this going for them, I won't even waste my time with an SSE, but they just might be the right part for a vacuum tube guitar amp powered by a single 6V6 on about 300 volts.
 

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Those look exactly like the generic 5K transformers that came with a $110 ( including shipping ! ) 6P3 amp kit I got from Banggood. I haven't tried them yet.

There is some discussion about them in the most recent thread on the cheap China amp kits a couple of years ago. Many people were saying they're not all that bad.

I think most of this China stuff is sort of like Forrest Gump's mom's box of chocolates - you never really know what you're going to get.
 
Based on these glowing recommendations, I ordered one of these transformers from Amazon.

The specs say it all "Maximum Power Per Channel: Above 200W"...."Winding method; 3+2 fever grade winding."

Two hundred watts through a transformer that weighs about 1 pound, yeah right! Fever grade.....these transformers come with the virus baked in.

With all this going for them, I won't even waste my time with an SSE, but they just might be the right part for a vacuum tube guitar amp powered by a single 6V6 on about 300 volts.

Just a few things:

1) Glowing recommendations? Where?

2) The OPTs you ordered are completely different than the ones I received. Yours look to be about half the size and weight of the ones I bought. I have never hooked mine up because I also ordered Transcendars and decided to skip the Chinese ones for my SSE build.

3) I may try the Chinese ones just out of curiosity if I ever get my SSE working.
 
Good luck.
As you confirmed the combined price, including shipping is quite attractive.

IF they did a reasonably “good job” spinning the windings and securing the taps, then you ought to have a decent transformer pair. Out of curiosity, how much is the shipping weight?

The answer says a lot as to whether “enough materials” were used.

⋅-=≡ GoatGuy ✓ ≡=-⋅

I neglected to reply later about the weight of these Chinese transformers. Sorry about that.

They are ~990 grams each, which is somewhere between the weight of Transcendar's 5w (800g) and 7w (1100g) single-ended OPTs. Edcor's GXSE 10w 5k weighs 793g.
 
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