yes, that's fine!
For the bias voltage of 50V, a small print transformer is sufficient
48V or 2x24V, which can be easily installed inside the housing !
https://www.ebay.com/itm/273790508088
Nice r-core transformer, a bit oversized with 30 VA but 115V primarily for the USA,
small print transformers like those available in Europe don't seem to really exist in your area!?
For the bias voltage of 50V, a small print transformer is sufficient
48V or 2x24V, which can be easily installed inside the housing !
https://www.ebay.com/itm/273790508088
Nice r-core transformer, a bit oversized with 30 VA but 115V primarily for the USA,
small print transformers like those available in Europe don't seem to really exist in your area!?
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I haven't ordered anything yet. My concern is any duty/customs fees I might incur. These are for the uncovered "naked" ones. Doing a little quick math conversion it would be approximately be $816 for the supremes vs the $332 for the naked. The PT's are over $300 each for the supremes. For $800+ dollars I'll buy a finished amp.
ON the other hand I can get Antek covered power transformers for $200/pr (only $120/pr uncovered). Put a 50V under the chassis and use a regular OPT (Edcor or the like) for ~$280/pr. So not much more than the naked toroidy and no risk of import fees.
I'm saying $800+ on just transformers. You are basically paying a premium for shiny chrome covers. If I pay that and another $600 or so dollars for the parts to finish it decently with MODEST parts and enclosure (easily could be more with boutique parts and custom enclosures), I could easily spend $1500 on a finished product (especially used) and not have the hassle of building one (Black Ice F22 or a Line Magnetic 211IA). I'm on a yearly budget as well. Most of it is being used on new speakers.
I know DIY isn't about saving money, at least in this hobby, but there comes a point where you can purchase a product that's equal to what you're building for relatively the same cost. Now if you're trying to match a boutique company's build, then you can a lot of times save money as those products are oftentimes very price inflated. But his isn't the case with this amp.
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Good to know you can still buy Toroidy from TME.com. I agree with the cosmetics of the shiny coveres not being worth more than double the money.
I have ordered as many as 4 transformers at a time individually with total value similar to your quote and they were delivered without customs duty. Good luck.
Most of this is just FYI.
And.......just like that denied at the goal. Right before I called to order, TME contacted me that they are not able to import the transformers into the US. Again. I responded but am still waiting on a response from them.
I contacted Toroidy directly and was given the following quote:
2 x TTG-EL34PP
Audio grade transformers cost: 70,52 EUR/pc (EXPORT PRICE)
2 x TSTA-250-001 PRI: 2 x 115V
Audio grade transformers cost: 88,11 EUR/pc (EXPORT PRICE)
Shipping cost to zipcode.../USA: 89,00 EUR (EXPORT PRICE)
$435 USD total for the Audio versions.
2 x TTG-EL34PP
Supreme version cost: 115,39 EUR/pc (EXPORT PRICE)
Side-wiring mounting plate for Supreme cost: 7,70 EUR/pc (EXPORT PRICE)
2 x TSTA-250-001 PRI: 2 x 115V
Supreme version cost: 134,88 EUR/pc (EXPORT PRICE)
Side-wiring mounting plate for Supreme cost: 7,70 EUR/pc (EXPORT PRICE)
Shipping cost to zipcode..../USA: 121,00 EUR (EXPORT PRICE)
$665 total for the Supremes.
And.......just like that denied at the goal. Right before I called to order, TME contacted me that they are not able to import the transformers into the US. Again. I responded but am still waiting on a response from them.
I contacted Toroidy directly and was given the following quote:
2 x TTG-EL34PP
Audio grade transformers cost: 70,52 EUR/pc (EXPORT PRICE)
2 x TSTA-250-001 PRI: 2 x 115V
Audio grade transformers cost: 88,11 EUR/pc (EXPORT PRICE)
Shipping cost to zipcode.../USA: 89,00 EUR (EXPORT PRICE)
$435 USD total for the Audio versions.
2 x TTG-EL34PP
Supreme version cost: 115,39 EUR/pc (EXPORT PRICE)
Side-wiring mounting plate for Supreme cost: 7,70 EUR/pc (EXPORT PRICE)
2 x TSTA-250-001 PRI: 2 x 115V
Supreme version cost: 134,88 EUR/pc (EXPORT PRICE)
Side-wiring mounting plate for Supreme cost: 7,70 EUR/pc (EXPORT PRICE)
Shipping cost to zipcode..../USA: 121,00 EUR (EXPORT PRICE)
$665 total for the Supremes.
TME now says they can import them. Jeesh?
As I make up my mind, can someone help with using a CT EI transformer instead of the toroidy. I'm assuming a fullwave offboard rectifier for the HV. Not usre on the cap value, but a 600VCT transformer should be oK for a monoblock I'd think. I'm thinking that will put out about 400V into the PS PCB. What I'm not sure about are the 6.3V connections.
As I make up my mind, can someone help with using a CT EI transformer instead of the toroidy. I'm assuming a fullwave offboard rectifier for the HV. Not usre on the cap value, but a 600VCT transformer should be oK for a monoblock I'd think. I'm thinking that will put out about 400V into the PS PCB. What I'm not sure about are the 6.3V connections.
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@bloozestringer ,
Thanks for sharing this info. Good to hear we (in the US) can still buy Toroidy transformers directly for a decent cost inclusive of shipping from Poland. If TME wants to play let them compete!
Thanks for sharing this info. Good to hear we (in the US) can still buy Toroidy transformers directly for a decent cost inclusive of shipping from Poland. If TME wants to play let them compete!
It depends on what you want to do and what CT EI transformers you are considering. Are you thinking of using the PS PCBs from Prasi’s GB?
If so, the requirements for the BHEL34 PCB (Mk2) are shown in the wiring diagram. It will complicate things a bit if you don’t use the specified Toroidy power transformer although alternatives could be worked out with additional transformers, etc.
B+ from a 600 VCT EI transformer should be OK, but BH requires -100Vdc AND +15 Vdc for bias. The PS board also needs 12vdc for the delay relay. As shown, Marc anticipated the use of a DC/DC converter to take the 15Vdc ( rectified 6.3-0-6.3 (at 7 amps) of the Toroidy PT) to the required 6.3 Vdc for heating. Several builders reported that they experienced no issues or hum with AC heaters.
Bottom line is that IMHO you will pay more for CT EI power transformers to meet all the requirement than to buy the Toroidy’s. But perhaps you have those EIs waiting in you parts box.
So essentially you could use a 600VCT@200mA with a 50V tap and 6.3V/2-3A. You'd have to add another transformer for the the other 6.3 V? Something like the Antek AS-1206 (6V@8.3A x 2) or any other 100VA dual 6.3V secondary transformer?
It's an exercise more than anything just to see the options.
It's an exercise more than anything just to see the options.
Thanks. I'm sure I'll go with the Toroidy transformers, but it's nice to have options and a plan to implement them. I really appreciate all your help with everything!
Got the transformers from TME. Can’t believe they aren’t physically ruined. Might as well if put nothing in the shipping box ( a few wads of bubble wrap was it and box was falling apart). Not mounting hardware or anything with them, but maybe that’s how they come from Toroidy. I’ll need to check the PT’s to see if they still work. Last time I order anything from Europe like this.
That happened to me a few years ago, apparently they haven't learned anything! At that time they were TGL 40/001, ordered from TME-EU and delivered from Poland. The mounting brackets and some soldering lugs were bent and the copper foil was damaged. I took photos and negotiated a discount. Luckily the electrical functions were fine.
Order something like this, there is a mounting plate available 
https://de.aliexpress.com/item/1005005080334914.html
https://de.aliexpress.com/item/1005005080334914.html
Do the covers just friction fit on those plates or just bolt to the plates (then to chassis)? I’m assuming the transformer bolts to the plate, then the plate to the chassis?Order something like this, there is a mounting plate available
I’ve seen a few amps where those were mounted from the inside of the chassis. A large hole for the cover, cover voted to chassis top, and an aluminum plate inside that the transformers are mounted to. Very clean like this, but I imagine a pain to work on or replace the transformer if it needs it. Very slick though.
https://www.diyaudio.com/community/threads/photo-gallery.71300/page-559#post-7190244
The centre core part is epoxy, and I think it is possible to use something like an M6 bolt and tap the core itself. Otherwise I have fitted mine using a 1" washer and locknut, like you mentioned.