Yep I haven´t build the hole amp, just the output stage combined with another front end and eq. It sounds great! theres a build tread here on groupdiy...Ha!
Not seen that one before. Looks good. Very similar scheme for gain adjusting as the NWDR V41 and V76 amplifiers. Switchable output mode too.
Nice one Jonte if you see this.
Thanks Solkatten.
There are at least 2 treads in this forum in Jonte Knifs preamp. He is also the designer of some of the best mastering eq compressor and preamps money can but. Check out knifaudio.comThat's more current than usual for a first stage, isn't it? Might sound a little harsh?
It's all relative really. I'm only eyeballing the ECC88 curves on a laptop here, but it looks to be about 2.3mA in that first stage. That's certainly higher than the sub 1mA in the EF804S' anode in a V76. But not particularly high at all for an ECC88.That's more current than usual for a first stage, isn't it? Might sound a little harsh?
Hi I didnt build the front just the E81L output so I cant really comment on the subjective side of thingsThere was a period when I used to use very high voltages and the highest possible current in preamp and line amps, and there is some advantage to that. Transients are very quick, the sound is hard, not puffy, and in-your-face. There is a bit of a downside, when it comes to the first stages, though, and I am not sure if it was due to added distortion, or simply a question of aesthetics.
I'm sure it's a great preamp. My question was just to get some subjective opinons. I can see the designer knows what he is doing.
It's all relative really. I'm only eyeballing the ECC88 curves on a laptop here, but it looks to be about 2.3mA in that first stage. That's certainly higher than the sub 1mA in the EF804S' anode in a V76. But not particularly high at all for an ECC88.
Where might you have placed it so it sounded less harsh Max?
I think he liked to keep the impedance low due to noise. The line stage has varying input impedance due to switchable local feedback and that starts to interact with the high pass filter, if not buffered. I built mine with a 100k pot and a 100k buffer resistor in the grid circiut of the line stage. It worked fine, that put the max grid leak value in the 200 K range.
High enough not cause a rise in distortion and low enough not to exceed grid leak value and excess noise... I guess... The noise issue isnt a big one....what kind of noise? hum?
Ahh nice... but it seems hard to find a preamp with a PCB at that B+?Many early RCA preamps are 180V, though with DC feed output transformers.
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