Maybe this is a stupid question and discussed already, could not find anything...
Today I use a 300B- PP amp to drive my speaker and at 450V/60mA/6k is has enough power to do what ever needed.
What I would like to do now is to figure out, if a SE-Output configuration can actually drive my speaker at all. So, I want to build a prototype, where ideally only the last stage gets exchanged, so no 300B in PP anymore, but a 520v3, gm-70,845 etc. The PSU and the transformers to do this are there, I can go up to 1000V if I have to and have Highquality Transformers with 2,7k, 3,5k, 7k, 10k.
The current amp is very simple: One 6sn7 driving an IT (Monolith ita-02 http://www.monolithmagnetics.com/si...stage transformer balanced bifilar prelim.pdf )in LTP-configuration, so a PP-IT In and Out on the seconday both ende to the grids of the 300B and a CT. My DAC has a tube stage which gives 16vpp output, thats why one 6sn7 is sufficient, I get a voltage swing from them of 200Vpp and can make this bigger or smaller as I like by changing the i/v-resistor of the DAC.
Now: Couldnt I simply take the whole secondary of the IT (instead of one half per tube, so NOT using the CT anymore), connect one end to neg grid supply and the other to the grid and we are done ? So, a PP-SE conversion / addition of the two anti-phase signals ? I understand that you can not use a transformer for SE on the primary side when it has been build for PP as the air gap is missing. So, we stay PP on the primary. But what about the secondary ?
It may sound weird as you would do a SE-Input stage as well, but this might come later, I want to figure out first if SE as a concept can drive my speaker at all and I want to be able to separate the effects of changes applied to my chain.
Today I use a 300B- PP amp to drive my speaker and at 450V/60mA/6k is has enough power to do what ever needed.
What I would like to do now is to figure out, if a SE-Output configuration can actually drive my speaker at all. So, I want to build a prototype, where ideally only the last stage gets exchanged, so no 300B in PP anymore, but a 520v3, gm-70,845 etc. The PSU and the transformers to do this are there, I can go up to 1000V if I have to and have Highquality Transformers with 2,7k, 3,5k, 7k, 10k.
The current amp is very simple: One 6sn7 driving an IT (Monolith ita-02 http://www.monolithmagnetics.com/si...stage transformer balanced bifilar prelim.pdf )in LTP-configuration, so a PP-IT In and Out on the seconday both ende to the grids of the 300B and a CT. My DAC has a tube stage which gives 16vpp output, thats why one 6sn7 is sufficient, I get a voltage swing from them of 200Vpp and can make this bigger or smaller as I like by changing the i/v-resistor of the DAC.
Now: Couldnt I simply take the whole secondary of the IT (instead of one half per tube, so NOT using the CT anymore), connect one end to neg grid supply and the other to the grid and we are done ? So, a PP-SE conversion / addition of the two anti-phase signals ? I understand that you can not use a transformer for SE on the primary side when it has been build for PP as the air gap is missing. So, we stay PP on the primary. But what about the secondary ?
It may sound weird as you would do a SE-Input stage as well, but this might come later, I want to figure out first if SE as a concept can drive my speaker at all and I want to be able to separate the effects of changes applied to my chain.
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Likely because the capacintance distribution won't be the same anymore and so the HF response/balance will be compromised
Well it is a bit more than hypothesis. If you change the voltage distribution across the winding the capacitance will change. Because you are reversing the phase of one the secondaries it (likely) might not symmetric respect to that change.
Just measure the FR monitoring the output as function of frequency.
Well, do we agree that the normal PP--->SE without impedance raise or decrease should be 1+1:2 ?
Maybe I got it wrong, but the diffential signal of the Output tubes (300b right now)normally gets summed up in the PP-Opt and becomes a double amplitude than each signal alone, right? And now we want this effect one stage eatlier, no ?
I will try something near to that as I do not want a different driver tube...
Maybe I got it wrong, but the diffential signal of the Output tubes (300b right now)normally gets summed up in the PP-Opt and becomes a double amplitude than each signal alone, right? And now we want this effect one stage eatlier, no ?
I will try something near to that as I do not want a different driver tube...
The output transformer has a capacitance distribution such that it is balanced when working in PP-to-SE mode. That's the difference. It has to do with the geometry which is not reflected in the turn ratio.
Yes. It's a quick check. Be careful about capacitances and use a probe where you can compensate.
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