ieales
Responses from ieales
| Tubes for a pre stage... matched NEW or unmatched identical NOS? 12au7’s in usa or european old stock form are plentiful and relatively inexpensive, even for well matched sets The problem is what is 'well matched'? At the datasheet params? NONE of my tubes operate anywhere near them. I've bought plenty of ... | |
| Tubes for a pre stage... matched NEW or unmatched identical NOS? What are your favorite 12au7 type NEW production? What amp? What purpose? What circuit? What music? What room? What system? ALL sound different in different places. The validity of most opinions is ZERO. And after how many hours as they chang... | |
| Recommendations for a vacum tube tester @scottya118 Are you technically capable of building one? I have schematic, PCB & CAD layout. PM if interested. | |
| Tubes for a pre stage... matched NEW or unmatched identical NOS? 12AU7-based mu-follower preamplifier stage driving a 100Wpc (into 8 ohm), class-D, solid-state power amplifier A mu-follower has plenty of gain which has to be padded down to drive the Hypex UcD-180 Class D. Weird. | |
| Tubes for a pre stage... matched NEW or unmatched identical NOS? The Sphinx likely uses tubes for the phono section, so low noise is paramount. For maximum RIAA fidelity and channel balance, the g1/g1 and g2/g2 sections need to be well matched, assuming the same topology for each channel. The big fly in the m... | |
| Tube amps - what 3 things… @alexberger The ESR would be quite different with parallel caps... and topology counts | |
| Tube amps - what 3 things… I compared sound with 100uF, 10000uF and 100000uF. It was a big difference in SQ between all 3 cases. Were they: the same technology the same size formed and capacitance verified Any of the above could change the SQ... and what reference... | |
| Tube amps - what 3 things… @atmasphere +1 | |
| Tube amps - what 3 things… Well designed autobias is precise. The tubes idle @ the setpoint very shortly after turn on and after several hours of robust use. It's probably an order of magnitude more precise that a pot and resistor in fixed bias designs. The biggest advanta... | |
| Tube amps - what 3 things… I am not a EE... Please don't post myths. I can assure that autobiased amps don't suck the headroom out of amps. As long as the bias time constant is long enough, the speakers will be toast long before the autobias affects the gain... assuming ... | |
| Tube amps - what 3 things… Only if you keep digging... | |
| Tube amps - what 3 things… Checking bias monthly is OK, but knob dicking the adjustment pots will shorten their life. Tweaking for the last fractional mA is pointless. Great amps were biased with moving coil voltmeters for decades before digimania took over. The bias is go... | |
| Tube amps - what 3 things… Ralph, stated another way, if the grid voltage remains constant as the transconductance changes, the current in a bipolar [CT] transformer will be unequal. Seems like a greater evil... unless one is OTL 😉 | |
| Tube amps - what 3 things… @atmasphere Great synopsis 👍 | |
| Tube amps - what 3 things… The ability to switch between modes (triode, ultralinear, pentode) is nice. A fish with wheels and wings would be nice too. Get a great sounding amp, not an overly complex spagheti bowl. +1 on P2P wiring with silicone or other high temperatur... |