Have anyone compared between either Allen's or Emile's Shunt Regulator and the one by Salas?
This built supply is not the needed supply for the real RTP3 but for is own need. For example there is no Logic Supply in the original. The included RTP3C schematic is very close to what is in the kit. Heater supplies are Current Regulator, not Voltage. Allen claims that they were always better. Make your choice and do some test, you'll easily find what proper voltage to use, to prevent regulator IC overheating and proper filament operation. If you add a choke inline you'll drop some voltage there as well. Again simulate with Duan PSU2 and you should have a good idea.
Don't forget that the current needed is different from tube type to an other. That prevent easy tube rolling in this preamp. Depending on tube you may need to change the current programming resistor of the current regulators...
One thing that help me reach the proper voltage with the Lundhall is that euro transformers are designed for 110V-115V primary. We have 120 in Canada. So transformer secondaries are always higher, even so if they are not fully loaded.
HV voltage value is a compromise between regulator power dissipation, what is needed at the preamp and proper regulator overhead input voltage. Get the original SVE SuperReg. It is explained in the doc, or read the notes on the schematic I posted. You'll get your answer.
Don't forget that the current needed is different from tube type to an other. That prevent easy tube rolling in this preamp. Depending on tube you may need to change the current programming resistor of the current regulators...
One thing that help me reach the proper voltage with the Lundhall is that euro transformers are designed for 110V-115V primary. We have 120 in Canada. So transformer secondaries are always higher, even so if they are not fully loaded.
HV voltage value is a compromise between regulator power dissipation, what is needed at the preamp and proper regulator overhead input voltage. Get the original SVE SuperReg. It is explained in the doc, or read the notes on the schematic I posted. You'll get your answer.
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My personal opinion (based on two versions of FVP5) is that heater supplies bring nothing to the amp. Its silent enough without it. Unnecessary bulk and expense.
Allen had very strong opinions on many things - and I am not certain I would agree with all of them or even many of them. The reason the preamp sounds so go is mainly because of the incredibly good topology which delivers at least 80% of the performance. You can go chasing the final 20% all you like but its going to cost - and you are never going to be satisfied.
Shoog
Allen had very strong opinions on many things - and I am not certain I would agree with all of them or even many of them. The reason the preamp sounds so go is mainly because of the incredibly good topology which delivers at least 80% of the performance. You can go chasing the final 20% all you like but its going to cost - and you are never going to be satisfied.
Shoog
Im pretty much satisfied right now, and nothing to improve further
but why should that stop me having fun
ok, thats a good reason
hmm, my immediate 'humble' calculation says that a 5% variation of 230V mains voltage, equals roughly 0.3V on 6.3V heaters
which is just within the specs, and thus no problem, if well adjusted
no ?
but with series heaters the voltage variation could be twice as much, and different, I guess
hmm, my immediate 'humble' calculation says that a 5% variation of 230V mains voltage, equals roughly 0.3V on 6.3V heaters
which is just within the specs, and thus no problem, if well adjusted
no ?
but with series heaters the voltage variation could be twice as much, and different, I guess
when you're going with AC , that's old school approach , in which case you're accepting these things .
if you're caring more about those things - go for DC and regulate
for indirectly heated tubes I prefer constant current approach for any type ( be it current or voltage primary defined ) and for DH tubes - see Rod Coleman's approach
if you're caring more about those things - go for DC and regulate
for indirectly heated tubes I prefer constant current approach for any type ( be it current or voltage primary defined ) and for DH tubes - see Rod Coleman's approach
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Well Allen was reaching for the best sound and to build a reference class preamp, and he did it. If heater current regulator were maybe contributing to only 5% of it, he would certainly choose it.
And if you're trying to build as good a preamp, it is worth it to try it as well. It no big deal. Use one current reg per tube and adjust the current programming resistor according to the chosen tube. As simple as that.
This preamp was one of Allen life achievement. He worked on it for years, perfecting every aspects and working hard to extract as much juice as he can. I'll follow his advice any time
And if you're trying to build as good a preamp, it is worth it to try it as well. It no big deal. Use one current reg per tube and adjust the current programming resistor according to the chosen tube. As simple as that.
This preamp was one of Allen life achievement. He worked on it for years, perfecting every aspects and working hard to extract as much juice as he can. I'll follow his advice any time
I have been running the same tubes in my first FVP5 for about 7yrs now - with no sign of them going any time soon. That's been a lot of hours. I always run my heaters at 6V to prolong tube life (a proven method with no sonic penalties).
I would not dissuade anyone from pursuing their dream amp to the 'nth order - but just realise that beyond a certain point its mostly all in the mind. By choosing the design you are already at the top table as far as I am concerned, and I would bet that a cheap implementation would sound almost the same in a blind comparison.
Shoog
that's fun thing - taking care about details ;
when making your own ( either starting from scratch or by someone else's design ) some ppl are enjoying in every detail , some not .
there is nothing wrong in gilding the lily ; over-engineering can be wrong
in Allen's work I can't see one sole detail of over-engineering , and some things reminding to gilding the lily are , say , precautions developed in many years of work .
edit: not arguing or debating ..... just contemplating about things which I can see in my own approach to .... gilding the lily
sheer pleasure sometimes can be valid reason .
when making your own ( either starting from scratch or by someone else's design ) some ppl are enjoying in every detail , some not .
there is nothing wrong in gilding the lily ; over-engineering can be wrong
in Allen's work I can't see one sole detail of over-engineering , and some things reminding to gilding the lily are , say , precautions developed in many years of work .
edit: not arguing or debating ..... just contemplating about things which I can see in my own approach to .... gilding the lily
sheer pleasure sometimes can be valid reason .
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LM317 as CCS is good enough for purpose , if you're keeping HF garbage out of heater circuit , just because 317 is good as snail in suppressing high freq noise;
elevating heater potential to proper voltage is a must , both for "lower" and "higher" triode systems in stage , with purpose to prevent any possible leak between heater and cathode;
I paid my school about that , building Anzai pre from Elektor , when I was a kid ; it took me 4 years of learning things to make proper preamp of it
elevating heater potential to proper voltage is a must , both for "lower" and "higher" triode systems in stage , with purpose to prevent any possible leak between heater and cathode;
I paid my school about that , building Anzai pre from Elektor , when I was a kid ; it took me 4 years of learning things to make proper preamp of it
AFAIK, there is no HF oscillations caused by the heaters. DC elevation of the heaters is a good thing to do and it's mentioned in Allen's schematics. LM317 is fine as either voltage or current regulator for the heaters.