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Tubelab SSE Power Transformer Specs

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Tibetan

Tibetan

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Joined 2022
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#1
I just purchased the PCB for this amp and I'm beginning to put the parts list together to find out how much I will have to spend when I go shopping. I did a search that turned up a lot of hits but I didn't see a specific answer to my question (maybe because I didn't ask it correctly). I have spent a lot of time on George's site but, as he himself says, much of the info there is 15 years old.

I'm building this amp with the intention of running the EL34, 6CA7, KT77 family of tubes, mostly in triode mode. I intend to include the optional switch between tube and SS rectification. Source is Tidal streamed through a DAC. Speakers are 8 ohm rated nominally @ 97dB sensitivity.

Question with respect to the power transformer: what range of maximum current ratings should I be looking for - minimum, desirable, etc. ?
 
#2
Tibetan said:
Speakers are 8 ohm rated nominally @ 97dB sensitivity
Click to expand...

What does the impedance curve look like. I “have” an SSE tht George built. But it never got converted to 6V6 and i fear both it and the East German OPTs are gone.

George is here answering queries and there is already a significant amount of info on this amplifier.

Where are you on the island?

dave
 
#3
I don't have a measured impedance curve. This is the nominal one published by the manufacturer.

I'm in the Cowichan area.

Specs.png
 
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#4
A Lii? It has already been discussed that the provided data is largely nonsense. Makes them difficult to work with.

What enclosure?

With the high Roout of the SSE, anywhere the impedance is higher the amplifier will put out more power. Can’t say what the bass looks like (cabinet dependent), but if the graphs are at all real likely an elevated top. And with the high Qms (just looking at thr impedance curve), you may require more damping to get the bass right.

You are just up the “street”. I’m at the top of the pass over Mt Finlayson.

dave
 
#6
Tibetan,

For the tubes you listed, you need a power transformer with rated for 750V AC with Center Tap. You can find more details here:

http://tubelab.com/designs/tubelab-sse/applications/

I used the Hammond 374BX - Specs: Universal - 100, 110, 120, 200, 220,230, 240 VAC 50/60 Hz · 750V C.T. @ 201ma, 5V C.T. @ 3A, 6.3V C.T. @ 6A.

Please be careful and follow all necessary safety precautions - the high voltages in a tube amp can be lethal.
 
#7
@zman01 Thanks, I had overlooked that section on the Tubelab site but independently came up with this Edcor as being suitable:

Edcor XPWR002

I hear your caution: This is not my first build, I have built one simple tube amp kit in the past and my bass guitar amps are tubed. I'm not an expert but I am very much aware of the potential harm.
 
#11
Tibetan,

Good luck with your build.

Btw, the Hammond 374BX is also priced in the similar ball park and is an off the shelf product, whereas the Edcor possibly will be built to order? The Hammond also has multiple options for selecting the primary AC voltage.

What output transformers are you planning to get?
 
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#12
zman01 said:
Here's another option if you want a slightly higher B+ vs the XPWR002:

https://edcorusa.com/products/xpwr222-750v375-0-375-350ma-6-3v-6a-5v-6a
Click to expand...
This one may be a bit too big, especially if your line voltage runs high. The SSE will draw less than 200 mA from the HV winding, 2 or 3 amps on the 5 volt winding and 3 to 5 amps on the 6.3 volt winding. The XPWR222 is rated for much higher current so it will put out more than its rated voltage when lightly loaded. I would go with the 374BX or XPWR002.
 
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#14
zman01 said:
Tibetan,

Good luck with your build.

Btw, the Hammond 374BX is also priced in the similar ball park and is an off the shelf product, whereas the Edcor possibly will be built to order? The Hammond also has multiple options for selecting the primary AC voltage.

What output transformers are you planning to get?
Click to expand...
I haven't made any firm decisions about any components at this early stage - just scoping out what's available with appropriate specs and at what cost.

George has a lot of info about OPT on the Tubelab site so I will certainly be guided by what's there. This transformer maker was also recommended to me but I can't find much info about them. Anyone have any info?

Thermionic Labs
 
#15
Tubelab_com said:
This one may be a bit too big, especially if your line voltage runs high. The SSE will draw less than 200 mA from the HV winding, 2 or 3 amps on the 5 volt winding and 3 to 5 amps on the 6.3 volt winding. The XPWR222 is rated for much higher current so it will put out more than its rated voltage when lightly loaded. I would go with the 374BX or XPWR002.
Click to expand...

George,

Thank you for chiming in!
 
#17
Given all the people complaining of buzzing Edcor power transformers, I'd spend the extra on a Hammond. Also, if there is an issue with your Hammond, getting a replacement would actually be possible. Good luck getting a replacement from Edcor.

jeff
 
#20
vinylkid58 said:
Given all the people complaining of buzzing Edcor power transformers, I'd spend the extra on a Hammond. Also, if there is an issue with your Hammond, getting a replacement would actually be possible. Good luck getting a replacement from Edcor.

jeff
Click to expand...
Thanks for the heads up and the link! I don't know enough about transformers do know what might be the problem but I don't need the headache of trying to resolve it. Scratched from the list unless/until the issue is identified and fixed.
 
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