YA aikido...
For the spirit of sharing (or just for the record), here is another aikido linestage with 6sn7/6sn7 octal board and a 3-switch attenuator, all from Tubecad.com. Passive-outs are added to the rear upper-left. It has an all aluminum case (fleamarket IBM research lab) and African rosewood trims, with rca jacks from partsconnexion. The knobs are from a fleamarket Grass medical research amp. Jensen and Auricap output caps are used. It has a 12.6V AC filament, +300V HV, no choke, plus a full-wave s.s. diode rectifier.
Very subjective listening impression - Semi-AB(?) compared to a McIntosh C20 preamp with treble and bass controls set to middle of the range. Same solid state amp and speakers were used. A 5 minute section of the Hilary Hahn, Natalie Zhu (Mozart violin sonatas) CD was played continuously for about 4 hours, with the two preamps switched at random times (not blindly as I did that by myself). Conclusion: Both sound very nice but the old C20 sounds a little bit more "refined (or warmer?)" - may be not all its shaping circuits were defeated, or the old (leaky?) components added a pleasant distortion to the sound. I would give the edge to the C20 at this point, at least for simple instrumental music. Projectwise, the main problem had been trying to reduced the hum of the aikido (posted at this forum before - http://www.diyaudio.com/forums/showthread.php?s=&postid=992945#post992945
). Conclusion - the aikido preamp is good and worth the effort.
For the spirit of sharing (or just for the record), here is another aikido linestage with 6sn7/6sn7 octal board and a 3-switch attenuator, all from Tubecad.com. Passive-outs are added to the rear upper-left. It has an all aluminum case (fleamarket IBM research lab) and African rosewood trims, with rca jacks from partsconnexion. The knobs are from a fleamarket Grass medical research amp. Jensen and Auricap output caps are used. It has a 12.6V AC filament, +300V HV, no choke, plus a full-wave s.s. diode rectifier.
Very subjective listening impression - Semi-AB(?) compared to a McIntosh C20 preamp with treble and bass controls set to middle of the range. Same solid state amp and speakers were used. A 5 minute section of the Hilary Hahn, Natalie Zhu (Mozart violin sonatas) CD was played continuously for about 4 hours, with the two preamps switched at random times (not blindly as I did that by myself). Conclusion: Both sound very nice but the old C20 sounds a little bit more "refined (or warmer?)" - may be not all its shaping circuits were defeated, or the old (leaky?) components added a pleasant distortion to the sound. I would give the edge to the C20 at this point, at least for simple instrumental music. Projectwise, the main problem had been trying to reduced the hum of the aikido (posted at this forum before - http://www.diyaudio.com/forums/showthread.php?s=&postid=992945#post992945
). Conclusion - the aikido preamp is good and worth the effort.
Attachments
An externally hosted image should be here but it was not working when we last tested it.
WOW !!!
I, for one, would like to know more about this.
Post the circuit, please.
Andy
OTL headphone amp.
OTL headphone amplifier based on two SRPP stages (E80CC and ECC99).
Max output level is 8.4V rms into 220 ohm.
Distortion is 0.15% THD @ 1V rms.
OTL:
Schematic:
Jan E Veiset
OTL headphone amplifier based on two SRPP stages (E80CC and ECC99).
Max output level is 8.4V rms into 220 ohm.
Distortion is 0.15% THD @ 1V rms.
OTL:
An externally hosted image should be here but it was not working when we last tested it.
Schematic:
An externally hosted image should be here but it was not working when we last tested it.
Jan E Veiset
Here is what the power supply looked like on my drawing board. I did not follow the schematic 100%, the diodes (1N4004) that elevate the 7812 output voltage from 12V to 12.6V are left out and each 7812 feeds the filaments for one channel, etc.
OTL Power supply:
The output serial resistors are 120 ohms. That will reduce the power into low impedance headsets but also increase the S/N. When using a 39 ohm load, max Vout is ~1.5Vrms, which is more than enough to drive low impedance, high efficient Grados, for example.
A picture from the test bench:
1. e4 e6, your move
Jan E Veiset
OTL Power supply:
An externally hosted image should be here but it was not working when we last tested it.
The output serial resistors are 120 ohms. That will reduce the power into low impedance headsets but also increase the S/N. When using a 39 ohm load, max Vout is ~1.5Vrms, which is more than enough to drive low impedance, high efficient Grados, for example.
A picture from the test bench:
An externally hosted image should be here but it was not working when we last tested it.
1. e4 e6, your move
Jan E Veiset
