I have built two of the same amp (for different rooms...). both the same output tx, both reg salas hv PS.... they are the same.
They sound identical, there is no way i could tell a difference.
So, i decided to play with CCS fets (cascode and not). My ears are ok, but nothing special.
In short, DN2540 and IXTP08N100D2 impart a sound signature that you can hear relatively easily.... the IXTP08N100D2 is better, more open, more space (which in my opinion is just better treble at the top end).
Edit -
Also, sic diode bias sound better than blue led.
They sound identical, there is no way i could tell a difference.
So, i decided to play with CCS fets (cascode and not). My ears are ok, but nothing special.
In short, DN2540 and IXTP08N100D2 impart a sound signature that you can hear relatively easily.... the IXTP08N100D2 is better, more open, more space (which in my opinion is just better treble at the top end).
Edit -
Also, sic diode bias sound better than blue led.
gain? that was my first thought. Scope says not.
and this does pain me slightly as it sounds a bit snake oil right? the engineer in me doesnt like it. In cascode, impendance differences must be vanishingly small...
Currently the test setup looks like this:
and this does pain me slightly as it sounds a bit snake oil right? the engineer in me doesnt like it. In cascode, impendance differences must be vanishingly small...
Currently the test setup looks like this:
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From audioasylum : John, you really should try the IXYS version. They eliminate the veiling heard in the Supertex depletion-mode mosfets, and they have increased dynamics as well. I have used both mosfets in the earlier and most recent version of the K&K cascode CCS kit (on plate and cathode tail applications). They are simple to adjust with a variable resistor and sound really excellent
I cascode DN2540s with IXYS 10M90S as upper device and get great results. Edges are very fast with no overshoot. Other upper devices have given significant ringing on fast edges. That's my measurement experience.
I remember Gary Pimm having measurements of several css's. And output capacitance correlated with perceived sound quality. Low capacitance.. =good sound. If I remember correctly.
yeah, no issue, and both set to be the same. honestly, the amps are identical.
to be super clear, the dn2540 sounds fantastic. with a d3a or 6e6p, we are talking a seriously lovely sound, zero audible noise etc.
The IXTP sounds fantastic, but slightly different, just a bit more forward. The bits that making me hesitate is the gain question.... is it just slightly high gain (which in my experience leads to the sorts of comments like 'greater impact, more dynamic').
Comments like 'greater impact, more dynamic' tends to suspicion of 3d harmonic. Measurements should reveal. Do not get me wrong, I am not equipped with fine measurement instruments either. I am using dn2540 (not stacked) for G2 regulation and wonder if it has impact on reproduction quality which i found 'a little dark'.
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Obviously the impedance of a CCS is not the same with different transistors ( other transconductance and so on ) ... if you don't tweek it somehow . This alone could change the sound ( the way the tube operates ) .
Hello all,
can anyone help me how to figure IXTP08N100D2 current setting resistor value? I need about 40ma through IXTP08N100D2. Thanks.
can anyone help me how to figure IXTP08N100D2 current setting resistor value? I need about 40ma through IXTP08N100D2. Thanks.
If you could share your schematic, we could know what function this part is responsible for in your amp. The IXT part conducts about 10x the current so you need a bigger source resistor value. From the IXT data sheet that part will require more than -2V, maybe -3V to keep it down to 40mA. So the Source resistor would be about 3V/0.04A=75 Ohms. This is down in the bottom of the graph so it's just an estimate, and parts vary a lot.
Pete Millett CCS using IXTP08N100D2: http://www.pmillett.com/CCS.html
It would be interesting to take two of Pete's devices, one with DN2540, the other with IXTP08N100D2, with two D3a amplifiers and apply the outputs to a diff amp and see if there is a difference under different types of musical instruments.
It would be interesting to take two of Pete's devices, one with DN2540, the other with IXTP08N100D2, with two D3a amplifiers and apply the outputs to a diff amp and see if there is a difference under different types of musical instruments.
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