Thanks Chaps for the feedback on the ATI chassis! It is a $1000.00 to ship two of them to my door.
Saves a lot of time?
Vacation vs. Amplifier Chassis? Strangelove, that is a good one! Yes I'm certain the wife would prefer another noisy amp in the home vs. 2 weeks chillin' on a cruise ship.
Cheers,
Shawn.
Saves a lot of time?Vacation vs. Amplifier Chassis? Strangelove, that is a good one! Yes I'm certain the wife would prefer another noisy amp in the home vs. 2 weeks chillin' on a cruise ship.
Cheers,
Shawn.
Krell??
Hi everybody,
I begin to build this Krell style amp, for the input stage, I don't have a good complement pair of trans (NPN and PNP).
Can I use 2sc2383, 2sa1013. but I'm not sure about whether these trans are faked.
I have genuine too Mpsa 42/92 but gain and noise characteristics is not desirable.
I also have a hundred of genuine 2N5087 and bc546. Can I combine these trans in the input stage, cascoded version.
Hi everybody,
I begin to build this Krell style amp, for the input stage, I don't have a good complement pair of trans (NPN and PNP).
Can I use 2sc2383, 2sa1013. but I'm not sure about whether these trans are faked.
I have genuine too Mpsa 42/92 but gain and noise characteristics is not desirable.
I also have a hundred of genuine 2N5087 and bc546. Can I combine these trans in the input stage, cascoded version.
Group Buy for Chassis ?
Hi
I am keen to have a Krell Clone chassis that looks professionally made and that would not look out of place amongst my other commercial equipment. I also suspect from a sonic perspective this amp is worth the expense of a proper chassis.
The ATI box looks good but personally I would prefer even better heatsinking.
I am very much in favour of exploring the possibility of a group buy. A group buy might just be a cheaper option versus having a chassis build privately.
Alternatively we can decide on a fixed front chassis dimensions and then have a faceplate made in a groupbuy. That could still give a professional look if the amp is rack mounted.
Does anybody have any good contacts in this regard ?
Jozua
Hi
I am keen to have a Krell Clone chassis that looks professionally made and that would not look out of place amongst my other commercial equipment. I also suspect from a sonic perspective this amp is worth the expense of a proper chassis.
The ATI box looks good but personally I would prefer even better heatsinking.
I am very much in favour of exploring the possibility of a group buy. A group buy might just be a cheaper option versus having a chassis build privately.
Alternatively we can decide on a fixed front chassis dimensions and then have a faceplate made in a groupbuy. That could still give a professional look if the amp is rack mounted.
Does anybody have any good contacts in this regard ?
Jozua
Not a bad idea at all about the faceplate. Laser/plasma cutting, brushing, anodizing and silkscreen becomes very cheap in large volumes. A custom-made power switch of aluminium with the same finish embedded in the plate also looks so much more professional than a tacky generic one, and if a proper diffuser can be organised for power LED it would be even better.
IMO something seriously worth considering.
IMO something seriously worth considering.
Thanks AVWERK. Must be something like that because there's no space foreseen on the component side. It's possible that this question was raised before but the thread is becoming a bit long to go back and search for it. It's also not mentioned in the "Everything You Need To Know About The KSA100 Clone Was But Too Afraid To Ask section", or I didn't see it.
Regards
Regards
It's nice to see people at last starting to build the amp, was wondering when the questions would start coming about the resistors I've placed at the bottom
And yes, there's no support for the 20pF cap since there was no space on the layout when I saw it on the original (not present on the schematic), so it has to be tack-soldered at the bottom too. All mentioned in the FAQ, but I guess the phrase "afraid to ask" should be replaced by "lazy to read"
And yes, there's no support for the 20pF cap since there was no space on the layout when I saw it on the original (not present on the schematic), so it has to be tack-soldered at the bottom too. All mentioned in the FAQ, but I guess the phrase "afraid to ask" should be replaced by "lazy to read"
I've received mine last week Only waiting for a few transistors and ZVN Mosfets and a package from Parts Connexion and I can begin as well. I've milled the driver heatsinks this weekend from old ones, took about 10hours and still not finished since they had to be sawed, drilled, some of the fins milled off clean, anodize removed, re-anodized (almost burnt myself to death with the acid), but they look almost identical to the original ones, just a little thicker
Only waiting for a few transistors and ZVN Mosfets and a package from Parts Connexion and I can begin as well. I've milled the driver heatsinks this weekend from old ones, took about 10hours and still not finished since they had to be sawed, drilled, some of the fins milled off clean, anodize removed, re-anodized (almost burnt myself to death with the acid), but they look almost identical to the original ones, just a little thicker Hi,
if you have not yet bought VR2 then I suggest some lower values for R36, R37 & VR2.
R36=430r
R37=2k4
VR2=1k
The bias current through Q13 is about 17mA and the resulting base current will be about 0.2mA.
The current through the resistor string R37 VR2 R36 is of a similar value. Ir36=0.65/R36~=0.65/1k5=0.43mA, when bias is set to maximum. Resistor current falls to just 0.2mA when VR2 is set to 1k75.
A small change in Q13 base current will have a very significant effect on the current passing through R37 and the resulting multiplication ratio will swing (unstable?) when Q13 base current varies.
Using reduced values for the resistor string will help to keep the multiplication ratio nearer to a constant value. Reducing R36 from 1k5 to 430r increases the maximum resistor current from 0.43mA to 1.5mA. This is still well within the current limit of a 300mW 1k multi-turn pot.
There may be an advantage to going even lower with these resistor values.
if you have not yet bought VR2 then I suggest some lower values for R36, R37 & VR2.
R36=430r
R37=2k4
VR2=1k
The bias current through Q13 is about 17mA and the resulting base current will be about 0.2mA.
The current through the resistor string R37 VR2 R36 is of a similar value. Ir36=0.65/R36~=0.65/1k5=0.43mA, when bias is set to maximum. Resistor current falls to just 0.2mA when VR2 is set to 1k75.
A small change in Q13 base current will have a very significant effect on the current passing through R37 and the resulting multiplication ratio will swing (unstable?) when Q13 base current varies.
Using reduced values for the resistor string will help to keep the multiplication ratio nearer to a constant value. Reducing R36 from 1k5 to 430r increases the maximum resistor current from 0.43mA to 1.5mA. This is still well within the current limit of a 300mW 1k multi-turn pot.
There may be an advantage to going even lower with these resistor values.
Yip that's right. On the later iteration of the board (which unfortunately reached Mark too late for manufacture) I made it better laid out. Depending on your predriver heatsink you can mount R37 on top, but if you use foldback type heatsinks as in the original then they'll be in the way.