JFET input, MOSFET VAS, LATERAL output = Perfect!!

[kees52]

Originally Posted by mikelm

Hi Kees,

That is a very nice circuit !

will have to try it sometime

well thank you, now you can use higer voltages with the limitations of the j fets.

[keantoken]

My amp starts at 120mV today, over time it will drift to below 10mV, unless something changed while I slept.

It is frustrating to me, not knowing whether the harshness comes from the recording or the amp.

Kenpeter, I took a look at those dual Jfet and it turns out they were 2N5564, not 5464 as you had wrote! So I can use them as either the input or CCS, or both, barring excessive inter-jfet capacitance.

http://www.datasheetcatalog.org/data...shay/70254.pdf

- keantoken

[GregH2]

Kean,

Maybe you need some compensation, either phase lag or lead?? It certainly has a treble smoothing effect.

[keantoken]

I have gone through many phases of adjusting my headphone amplifier. Generally what happens is I achieve greater resolution and a sense of space, and greatly improved clarity, but then the treble seems greatly emphasized, if not harsh. Is it possible it is because of my speakers?



I cannot be sure whether the harshness comes from the source or the amp. Once I switched back to my old Creative soundcard to help with harshness but again there was the loss of quality. Hmm. I wonder if positive phase shift in the treble is a factor here, because increasing the speed of the amplifier will decrease HF phase lag.

I added the VAS degeneration, and that calmed the sound a bit, but also seemed to lower quality in other areas. I am about to add the CCS.

- keantoken

[kenpeter]

You coulda used 6dj8 for all it matters...
Why we wasting the matched pair?

[keantoken]

I don't have any other jfets.

- keantoken

[Salas]

You wouldn't find one jfet as orange glowing as 6DJ8 even if you had Jako's stash of semis.

[Salas]

Originally Posted by keantoken

I have gone through many phases of adjusting my headphone amplifier. Generally what happens is I achieve greater resolution and a sense of space, and greatly improved clarity, but then the treble seems greatly emphasized, if not harsh. Is it possible it is because of my speakers?

Are they full range drivers? They look rugged around sibilance frequencies. They also need a lot of step correction. Much higher sensitivity up high.

[keantoken]

Yes, these:

Wild Burro Audio Labs - Fullrange Speakers - The Betsy & Betsy-K Drivers

- keantoken

[Salas]

Have been messing with analogous Hemp FR8s and they needed a low Q wide band in series notch filter (parallel RLC) to tame. Else, they were high forward. Or DSP of course. Try with a parametric EQ module from your PC and do the in/out filter A/B test to get an idea. Using a mic is the key, but you can start by roughly evening out that chart by ear try outs. Just to have a hint if its the amp or not.