Slewmaster - CFA vs. VFA "Rumble"

So it Kypton V not the ND that have issues. Did Kypton V2 have issues too?
apart from the super pair it has issues. I built over 10 of these channels and the sad part is sometimes you dont get the bias. Sometimes the bias is overshooting. Sometimes the leds dont glow.

I agree trouble shooting by the values and I got 3.3ma output from VAS.
It was very irritating some times that even after checking the Point to point contacts everything seems fine but it has these issues.
 
Did you show the instability and the solution/s in another post?


It's spread over multiple posts in the slewmaster builds thread. My problem was too high vas current.
Part of the problem was thermal coupling between Q3 and Q4. They have to be proper thermally connected to get the correct VAS current i used heat shrink instead of tie wraps to press them together, that helped reduce the current.
(Even blowing on these transistors will make the vas current drop).

I ended up changing all resistor values according to this schematic
512934d1446760316-slewmaster-builds-k-nd.jpg


If I remember correct I had to use 390r for R18 and R22 to drop the current a bit.

Here's a good explanation from OS how to tweak the knd.
http://www.diyaudio.com/forums/solid-state/260268-slewmaster-builds-132.html#post4507148

yngvejos,
I would think at the 80v rail level with both the KND and Spooky as good as they both are it would be hard to tell them apart? Is it just the bass end of the spectrum that makes you chose one over the other?

I couldn't really notice any difference in sound between knd and spooky.
The knd makes more noise on startup and shutdown (solved by adding protection boards) it's also more sensitive to RF noise. I had to bypass D1, D2 and R3 to make it quiet.

The reason I prefer the spooky is that it requires no fiddeling and tweaking for stable operation. ;)
 
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It's spread over multiple posts in the slewmaster builds thread. My problem was too high vas current.
Part of the problem was thermal coupling between Q3 and Q4. They have to be proper thermally connected to get the correct VAS current i used heat shrink instead of tie wraps to press them together, that helped reduce the current.
(Even blowing on these transistors will make the vas current drop).

I ended up changing all resistor values according to this schematic
512934d1446760316-slewmaster-builds-k-nd.jpg


If I remember correct I had to use 390r for R18 and R22 to drop the current a bit.

Here's a good explanation from OS how to tweak the knd.
http://www.diyaudio.com/forums/solid-state/260268-slewmaster-builds-132.html#post4507148



I couldn't really notice any difference in sound between knd and spooky.
The knd makes more noise on startup and shutdown (solved by adding protection boards) it's also more sensitive to RF noise. I had to bypass D1, D2 and R3 to make it quiet.

The reason I prefer the spooky is that it requires no fiddeling and tweaking for stable operation. ;)

Have you seen super nad schematic 1.1 where R10-13 are 56R and R18 +19 are 390R?

Happy building☺
 
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Thanks for all that and the links.
it's also more sensitive to RF noise. I had to bypass D1, D2 and R3 to make it quiet.
the Disconnecting Network is shown in the signal line. That is wrong. No wonder it makes extra noise.

The signal input circuit must allow signal current to Flow into the input AND must allow signal current to Return to the Source. That CIRCUIT must be complete.

Then one can add in a Disconnecting Network to attenuate interference current that passes around the loop of a stereo amplifier as shown by HBRL + HRRR in Joffe paper.
 
apart from the super pair it has issues. I built over 10 of these channels and the sad part is sometimes you dont get the bias. Sometimes the bias is overshooting. Sometimes the leds dont glow.

I agree trouble shooting by the values and I got 3.3ma output from VAS.
It was very irritating some times that even after checking the Point to point contacts everything seems fine but it has these issues.
I don't think so.
All these are tested IPS,no issue.
Kypton v is in post#5261 and the test is on post #5282.
 
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Me neither, tried many times in a polite way but no success. :rolleye
Please explain how to tell the guy, who claims two 50 W resistors in series form 50 W resistor, that all amps sound different? :confused:

Stop being such a troll. What I wrote about using the resistors was in error. That has nothing to do with the sound of the two amps that I was asked asked about.

You have admitted that you don't have access to a blind A/B setup. You have not built nor heard any of the Slewmaster amps, SO, commenting on someone's opinion about them makes you a huge TROLL. Go back to listening to your toy amps and leave me alone. Your comments here have no value.
 
I don't think you'll hear a difference in amplifiers with an AB test, or by running two different amps at the same time. The differences are too subtle for that. I still notice a difference after playing a few well recorded songs though. This will depend on your speakers, hearing, ect. I'm not claiming to have golden ears either. My hearing is damaged.