Antek Toroidal transformers

[labb]

Anyone used these? Price is really good.

[Paul1453]

Do you have a specific one and amp you want to use it on?

I have not used any yet, but I watch for good deals on transformers on Ebay all the time.

The toroidal transformers I have looked at all seemed to have a very low HV tap.
They would need a voltage doubler/tripler to get the B+ we normally use.
The applications I see them used on seem to be Hi-Fi headphone amps.

Maybe I was looking at the wrong ones?   

[labb]

http://www.antekinc.com/as-2t300-200va-300v-transformer/


That would give you 420 VDC with a bridge rectifier....330 MA if I read it right. They show a 350 volt


I have a AS-25T240  220/240 volt that I am going to try in a stand a lone pre amp.


Paul, take a look at these if you would. They are set up for tube amps. Have the 6.3 volt windings and all. Haven't seen any with the bias out but that is no biggy.

[Paul1453]

That price seems pretty good, but out of stock.

I didn't see any diagram of it available.
It would be good to know the exact specs. CTs etc.

330mA at 300VAC would be more than enough for most applications.

Maybe you'll have to take a chance on one, and let us know how it works out for you. 

[Clem Fandango]

Hello,

I have a recently purchased an Antek AS-2T300. It has two separate primary windings, DCR 10 ohms each. There are two separate high voltage secondary windings, DCR 54 ohms each. With 119 VAC on one primary, each HV secondary is 313 VAC unloaded. A 10K resistor load drops that to 311. There are no bias taps.  It has a winding with a single lead that I assume is the shield around the primaries.  The two separate filament windings are both well under 1 ohm DCR.

The HV secondaries are in a row, yellow-white-yellow-white. Connecting the middle two creates a center tap.

[pompeiisneaks]

This makes a question come to mind.  Is there any pro vs con of using torroidial for audio applications vs the more standard Transformer type?

[Bluemeany]

This makes a question come to mind.  Is there any pro vs con of using torroidial for audio applications vs the more standard Transformer type?

They hum less but they cost more.

[pompeiisneaks]

Ahh cool, thanks.

~Phil

[FranciscoPerez]

Large power transformers, especially toroidal types have inrush current that could damage the transformer or other components if not properly limited. That might be a con of using them for audio aplications.

[labb]

This company says to make toroidal transformer designed for tube amps. Low noise..


http://shop.plitron.com/shopdisplaycategories.asp?id=5&cat=Toroidal+Audio+Transformers

[sean_thornton]

I use toroidal xfmrs in most of my builds, but occasionally i r-core as well. I like them, a lot. Less noise and hum, they tend to run way cooler, and here in Europe they are cheaper than standard ones. I get mine from Tube-Town in Germany and the prices, even with shipping, are great.
The Antek ones are pretty well made and decently priced if you are in the US. By the time I pay for shipping, VAT, and import duty they are WAY too expensive for me.
I say try one, you might like them.

[FranciscoPerez]

Thanks for your post Sean_thornton.
I order from Tube-Town a lot, but never noticed they sell toroidals at such good prices!!


Cheers,
Fran

[vibrolax]

I've used about half a dozen AS-05T280 - 50VA 280V for preamp projects.  It's the smallest size they sell with HV + filament windings.

I haven't used them for a power amp yet.

They just barely fit in the Par-Metal 1U rack boxes I use for my preamps.
Par-Metal and AntekInc are owned by the same guy.

In the 50 VA size, I don't see any inrush current problems using a 1/2 A mains fuse.

[labb]

I have a AS-05t240 that I am going to use in a preamp project. I'm going to cheat and use a 2u box. This will be my first stand a lone preamp. Would love to pick your brain about grounding. You should check on the size available that have HV + filament windings..If I read the specifications correct they have several smaller in the 05T class. Pretty sure the 05T goes down to a 120 volt.  On second thought, the dimensions are the same if that is what you were referring to.

[vibrolax]

I have a AS-05t240 that I am going to use in a preamp project. I'm going to cheat and use a 2u box. This will be my first stand a lone preamp. Would love to pick your brain about grounding. You should check on the size available that have HV + filament windings..If I read the specifications correct they have several smaller in the 05T class. Pretty sure the 05T goes down to a 120 volt.

I know the 05T series is available with both higher and lower HV voltages.  I don't need lower voltages.  I'd like a slightly thinner unit that supplies about half the HV current (50 mA), instead of 100 mA.  The only issue with the 05T is fitting it into a 1U box.  But Antek doesn't do custom work, and I like the value I get from what they offer.

It's not cheating to use a 2U box.    It's easy to run out of front / real panel space.

Here's a link to my SVT preamp power supply layout: http://www.frontiernet.net/~jff/SonOfSVPCL/Images/Visio-AmpegSVTPreamp_PowerSupply_26Aug2014.pdf

The main project page is http://www.frontiernet.net/~jff/SonOfSVPCL/DIYSVTBassPreamplifier.html

I describe how I currently do grounding for preamps in the project pages.  In short, there is only one connection between chassis and signal ground: from the ground lug of the input jack to a nearby chassis bolt.  I use all isolated jacks (Cliff UK).  I connect an AC ground (1000 pF ceramic cap) from the output jack ground lug to the chassis to prevent RF from getting in.

That said, I've also used Hoffman-style grounding on various preamp and combo amp projects without a problem.

[labb]

Thanks. That is really nice...I will not be that complicated..Plan to use Hoffman's pre amp in a pedal box circuit less his PS end. Probably should have just used an AB 763 pre amp for the first one. But we shall see.
Do you have a separate ground point for the power supply and the first e-cap.

[sluckey]

That's a very impressive project and the documentation is super. You must have enjoyed all phases of that project very much.

[vibrolax]

Thanks. That is really nice...I will not be that complicated..Plan to use Hoffman's pre amp in a pedal box circuit less his PS end. Probably should have just used an AB 763 pre amp for the first one. But we shall see.
Do you have a separate ground point for the power supply and the first e-cap.

No, not for a preamp with a full wave bridge.  Here's my dual AB763 (dual showman-like) preamp in the same type box: http://www.frontiernet.net/~jff/SonOfAlembic/SonOfAlembicF2B.html

Same Antek PT.  AC filaments.

[vibrolax]

That's a very impressive project and the documentation is super. You must have enjoyed all phases of that project very much.

"Enjoy" is too strong of a word for the build phase, but I am quite proud of it.  I wish I liked the craftwork of building more, but I'm not gifted mechanically.  I undertook the SVT as a kind of "masters" project for myself, and developed the documentation because no one else seems to have done a documented layout/build before.  The reverse engineering of the midrange multitap toroid inductor was interesting.

A couple of folks have successfully built it from my docs, so I'm also pleased with that.

[tubenit]

Vibrolax,

I am also very impressed with your builds, the innovative approach and the documentation.  I hope you will be an active participant on the forum.  We would all benefit from your experience and expertise!

With respect, Tubenit