Nelson --
Thanks again for putting this together. It is interesting that you eliminated the cascode local feedback. How does that change the distortion harmonics between the two versions?
Thanks again for putting this together. It is interesting that you eliminated the cascode local feedback. How does that change the distortion harmonics between the two versions?
If you make the cascode feedback symmetric in value, it doesn't alter
the spectrum by much. You can make it un-symmetric if you like, in which
case you can have the 2nd harmonic as you like.
One of the things I like about cascode feedback is that it is a fine alternative
to degeneration of the input transistors, implementing more of a "Schade"
effect without compromising the power supply rejection.
Best done in small doses, though.
😎
the spectrum by much. You can make it un-symmetric if you like, in which
case you can have the 2nd harmonic as you like.
One of the things I like about cascode feedback is that it is a fine alternative
to degeneration of the input transistors, implementing more of a "Schade"
effect without compromising the power supply rejection.
Best done in small doses, though.
😎
Cap voltage
Hi,
Is it correct that the caps in the schematics need to be rated no higher
than 35V?
Thanks,
Dennis
Hi,
Is it correct that the caps in the schematics need to be rated no higher
than 35V?
Thanks,
Dennis
You can go higher but 50V caps:
1) Are quite a bit more expensive
2) Take up more room for the same capacitance value, which could mean you have to settle on a power supply with less capacitance than the amp may need depending on the powersupply pcb or space in your chassis.
Interestingly, while I don't care how excessive you get above the 35V figure
for the regulators and supply filters, I recommend that you use the values
of 47uF and 220 uF where noted. Increasing the 47uF to much higher
values slows the turn-on time to the bias circuit, and for some strange
reason much higher values on the 220 uF for the voltage references seems
to generate some stability issue with the TL431's with a little bit of motor-
boating (I know, it shouldn't).
😎
for the regulators and supply filters, I recommend that you use the values
of 47uF and 220 uF where noted. Increasing the 47uF to much higher
values slows the turn-on time to the bias circuit, and for some strange
reason much higher values on the 220 uF for the voltage references seems
to generate some stability issue with the TL431's with a little bit of motor-
boating (I know, it shouldn't).
😎
If you follow the email link you got from DIY store you can check your status (subscribed or not).
Have a look at Jasons post:
Ok, this only tells us HOW to get the kits, not exactly when.
Ok, this only tells us HOW to get the kits, not exactly when.
Last edited:
I believe they are packing them up as we speak. I am packing up another
150 pair of VFETs for shipment early next week.
😎
150 pair of VFETs for shipment early next week.
😎
Did the supplementary kits make into being? Or will it just be boards, T extrusions, and VFets?
Kudos to the diyA Store for the update/confirmation email today and the very fair system.
I'm getting all tingly so things must be really coming together.
And of course kudos to all others involved including NP!
BK
I'm getting all tingly so things must be really coming together.
And of course kudos to all others involved including NP!
BK
I have emailed all reserved + waitlist subscribers a confirmation email so you can feel assured you are properly registered. Please check your inbox and add contact@diyaudiostore.com to your address book. If it's not there, check your spam folder, and mark it as not spam. If it's in your promotions tab, drag it back over to your primary inbox. That way you can be sure the next email you get (from contact@diyaudiostore.com) will get straight into your inbox.
When they finally are available for sale, we'll be holding and double checking every order to make sure it matches the reservation list so nobody has to worry about missing out. If you have a confirmed reservation you will get a chance to buy a kit.
I've also added a new question at the bottom of the form to allow people to specify a preference (no guarantee) for purchasing only VFETs, only PCBs, only brackets or any combination of those. For those that are ordering 2 sets, you can specify if you would like 4 pairs of matched dual transistors by themselves - this is something we may be able to offer but again no guarantees. We'll do what we can 🙂
When they finally are available for sale, we'll be holding and double checking every order to make sure it matches the reservation list so nobody has to worry about missing out. If you have a confirmed reservation you will get a chance to buy a kit.
I've also added a new question at the bottom of the form to allow people to specify a preference (no guarantee) for purchasing only VFETs, only PCBs, only brackets or any combination of those. For those that are ordering 2 sets, you can specify if you would like 4 pairs of matched dual transistors by themselves - this is something we may be able to offer but again no guarantees. We'll do what we can 🙂