The direct heating triodes are really better?.
There are some Web where explains this?
I feel very intrigued by the FI 421A
http://www.6moons.com/audioreviews/fi6/421A.html
best regards Jaime
There are some Web where explains this?
I feel very intrigued by the FI 421A
http://www.6moons.com/audioreviews/fi6/421A.html
best regards Jaime
Jaime
No reason. On the contrary, there is a varying potential difference between parts of the filament and the control grid, so what is the actual bias? - etc. It is sometimes a little intriguing how, years after some developments have taken place and had been universally accepted as improvements, some visionaries would suddenly pop up and cause doubt as to which direction in audio is actually forward.
The F1 421A certainly looks neat, but I find the description too loaded with typical promotional fodder to mean much. (I mean: "When simple is best, that's the only ticket to bliss in valve land." Please!) Or simply swapping 6SL7s with 6SN7s?? I personally have a problem with exorbitant costing flea-power amplifiers - I built enough of them myself, and never found a good reason for using multibuck ultra-scarce tubage. Unless for collector's value, of course ...... But it is your money.
Regards.
No reason. On the contrary, there is a varying potential difference between parts of the filament and the control grid, so what is the actual bias? - etc. It is sometimes a little intriguing how, years after some developments have taken place and had been universally accepted as improvements, some visionaries would suddenly pop up and cause doubt as to which direction in audio is actually forward.
The F1 421A certainly looks neat, but I find the description too loaded with typical promotional fodder to mean much. (I mean: "When simple is best, that's the only ticket to bliss in valve land." Please!) Or simply swapping 6SL7s with 6SN7s?? I personally have a problem with exorbitant costing flea-power amplifiers - I built enough of them myself, and never found a good reason for using multibuck ultra-scarce tubage. Unless for collector's value, of course ...... But it is your money.
Regards.
I believe DHT is better. the low impedance and high linearity combined, is better. 6AS7 has very bad linearity.
My theory:
DHT are old; thus primitive tech; thus big distance between cathode and grill; thus better linearity.
newer diode's problem, newer tech; thus closer cathode and grill (for higher amplify factor); thus worse linearity.
If we can move the grill of new triode away from its cathode, we may get a triode that is better than those old DHT.
My theory:
DHT are old; thus primitive tech; thus big distance between cathode and grill; thus better linearity.
newer diode's problem, newer tech; thus closer cathode and grill (for higher amplify factor); thus worse linearity.
If we can move the grill of new triode away from its cathode, we may get a triode that is better than those old DHT.
I think the question to ask is whether builders who have used DHTs for a fair time (months, and with a really good filament supply) - and particularly small tubes like the 26, 12A, 01A etc - have gone back to using directly heated tubes and stated that they preferred the sound. I don't know any who have.
There are plenty of people who make comments about DHTs WITHOUT having had them in their own system (with a really good filament supply - RonanRegs, current sources etc) for enough time to get used to the sound, which is fairly generic in the case of the small DHTs. DHTs (like other things) aren't something you can evaluate without hearing them properly in a system you know well with your usual demo CDs or LPs.
Of course all evaluation of this kind is subjective, but so far I made a simple DHT preamp with a decent power supply and have taken it round to three friends. It was audibly more transparent with better timbre and tone than a 12b4, a 417a and a passive preamp. When these guys heard it in their own systems they could hear the difference.
I'm in London and we have an Audiocircle here, and one by one the members are going over to DHT small tubes. We all know the value of 845s, 300bs and 2a3s but the small tubes are something else and give a distinctive sound signiture right at the start of the amplification chain.
Why they do so construction-wise I don't know - wish I did. But the sound of the small DHTs has a distinct family resemblence - a certain clarity, sparkly top end, delicacy and good timbre to stuff like cymbals, grand piano, voice and woodwind. Once you identify it it's like women and chocolate - a craving that has to be satisfied. So something about them is different and quite distinctive.
There are plenty of people who make comments about DHTs WITHOUT having had them in their own system (with a really good filament supply - RonanRegs, current sources etc) for enough time to get used to the sound, which is fairly generic in the case of the small DHTs. DHTs (like other things) aren't something you can evaluate without hearing them properly in a system you know well with your usual demo CDs or LPs.
Of course all evaluation of this kind is subjective, but so far I made a simple DHT preamp with a decent power supply and have taken it round to three friends. It was audibly more transparent with better timbre and tone than a 12b4, a 417a and a passive preamp. When these guys heard it in their own systems they could hear the difference.
I'm in London and we have an Audiocircle here, and one by one the members are going over to DHT small tubes. We all know the value of 845s, 300bs and 2a3s but the small tubes are something else and give a distinctive sound signiture right at the start of the amplification chain.
Why they do so construction-wise I don't know - wish I did. But the sound of the small DHTs has a distinct family resemblence - a certain clarity, sparkly top end, delicacy and good timbre to stuff like cymbals, grand piano, voice and woodwind. Once you identify it it's like women and chocolate - a craving that has to be satisfied. So something about them is different and quite distinctive.
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