Actually the board works just fine. The actual board that you can buy has changed drastically so I wasn't planning on doing any further tests of the prototrpy board.
Mark
Mark
Sorry guys, 'cos of the thump, I couldn't help tweaking some more.
Well guessed Mark, I did have larger caps, but in C102/103. I swapped them out for the spec-ced 1000uF and the thump disapeared. But the amp didn't sound as sweet. So, if you're using a relay type turn on delay, then definately increase their value. I was using 1800uF Rubycon MBZs, and they were pretty good, however the ones I replaced them with were only "cooking" electros. I feel this is an area worth experimenting with.
I also tried the 2SC2240and 2SA970, and to be honest, I saw or heard no difference, so I will stick with the layout using MPSA42/92 throughout.
The amp is now running at 42V rails, 500mV bias and the only alteration required was increasing R122/3 to 150 Ohm, the existing 101 Ohm were running just a little hot for my liking.
Measured gain is about 22, and all seems stable with C105/6 at 22pF. These caps might possibly be reduced a little more, but this seems a good place to start.
I will start posting more stuff later, however progress depends on how distracting the Snooker World Championship final is! 🙂
Well guessed Mark, I did have larger caps, but in C102/103. I swapped them out for the spec-ced 1000uF and the thump disapeared. But the amp didn't sound as sweet. So, if you're using a relay type turn on delay, then definately increase their value. I was using 1800uF Rubycon MBZs, and they were pretty good, however the ones I replaced them with were only "cooking" electros. I feel this is an area worth experimenting with.
I also tried the 2SC2240and 2SA970, and to be honest, I saw or heard no difference, so I will stick with the layout using MPSA42/92 throughout.
The amp is now running at 42V rails, 500mV bias and the only alteration required was increasing R122/3 to 150 Ohm, the existing 101 Ohm were running just a little hot for my liking.
Measured gain is about 22, and all seems stable with C105/6 at 22pF. These caps might possibly be reduced a little more, but this seems a good place to start.
I will start posting more stuff later, however progress depends on how distracting the Snooker World Championship final is! 🙂
I would love a black ball final. They are both great players, but as a fellow Yorkshireman, I have to support Murphy as well!
A friend of me, who owns a KSA100, changed the two series cap's with one 470µF BG-N cap and he was very satisfied with that.
Cheers
P.S. Going back to the television now😀
If anyone is interested in more of the original boards, I have decided to sell them. I have 4 or 5 I think, I suddenly hit a wall of overwhelming last night when taking stock of my unstarted, not completed projects. It's just too much for me, I am going back to two tin cans and a length of string. It's sad to say but I have just lost interest in a lot of this hobby, it's become to cluttered with maths and numbers and tweaks and yadda yadda, I have not listened to a decent piece by Brahms, Chopin or Litz in far too long.
Please email me if you are interested.
Regards
Antrhony
Please email me if you are interested.
Regards
Antrhony
Wel Al, you didn't got your black bal finish but at least your man won.
A great final with a worthy champion.
Cheers
A great final with a worthy champion.
Cheers
Al,
I think you will find that it will sound its sweetest after it has some break in time, about 2 to 3 weeks. Also, letting it warm up for about 3 hours make s a huge difference. I used to let my KSA-80B run all the time unless I was traveling. It had similar characteristics as the 50. But this is an amazing amp for sure... very different from the ususal bi-polor stuff you see here. It has qualitites that no other amp seems to have, other than another Krell of similar topolgy.
Mark
I think you will find that it will sound its sweetest after it has some break in time, about 2 to 3 weeks. Also, letting it warm up for about 3 hours make s a huge difference. I used to let my KSA-80B run all the time unless I was traveling. It had similar characteristics as the 50. But this is an amazing amp for sure... very different from the ususal bi-polor stuff you see here. It has qualitites that no other amp seems to have, other than another Krell of similar topolgy.
Mark
And the parts list:
Partlist
Exported from KSAtest.sch at 5/03/2005 00:19:13
EAGLE Version 4.13r1 Copyright (c) 1988-2004 CadSoft
Part Value
C101 680p
C102 1000u
C103 1000u
C104 100n
C105 22p
C106 22p
C109 100n
C110 10u
C111 10u
C301 100n
C302 100n
C303 470u
C304 470u
D109 1N4148
D110 1N4148
Q1 MJW1302
Q2 MJW1302
Q3 MJW3281
Q4 MJW3281
Q5 MJW3281
Q6 MJW1302
Q101 MPSA42
Q102 MPSA92
Q103 MPSA42
Q104 MPSA92
Q105 MPSA92
Q106 MPSA42
Q107 MJE15033
Q108 MJE15032
Q109 MJE15032
Q110 MJE15033
Q111 MJE15302
R1 22k
R101 1k
R102 22k
R103 47k
R104 4k7
R106 4k7
R107 47k
R108 1k5
R109 1k5
R110 9k1
R111 9k1
R112 1k5
R113 1k5
R114 100R
R115 100R
R116 1K5
R117 1K5
R118 100R
R119 100R
R120 3k3
R121 3k3
R122 150R
R123 150R
R124 4k7
R125 820R
R126 5k
R127 25R
R128 25R
R129 1k5
R130 22k
R131 22k
R201 R68
R202 R68
R203 R68
R204 R68
R205 R68
R206 R68
ZD101 27V
ZD102 27V
Partlist
Exported from KSAtest.sch at 5/03/2005 00:19:13
EAGLE Version 4.13r1 Copyright (c) 1988-2004 CadSoft
Part Value
C101 680p
C102 1000u
C103 1000u
C104 100n
C105 22p
C106 22p
C109 100n
C110 10u
C111 10u
C301 100n
C302 100n
C303 470u
C304 470u
D109 1N4148
D110 1N4148
Q1 MJW1302
Q2 MJW1302
Q3 MJW3281
Q4 MJW3281
Q5 MJW3281
Q6 MJW1302
Q101 MPSA42
Q102 MPSA92
Q103 MPSA42
Q104 MPSA92
Q105 MPSA92
Q106 MPSA42
Q107 MJE15033
Q108 MJE15032
Q109 MJE15032
Q110 MJE15033
Q111 MJE15302
R1 22k
R101 1k
R102 22k
R103 47k
R104 4k7
R106 4k7
R107 47k
R108 1k5
R109 1k5
R110 9k1
R111 9k1
R112 1k5
R113 1k5
R114 100R
R115 100R
R116 1K5
R117 1K5
R118 100R
R119 100R
R120 3k3
R121 3k3
R122 150R
R123 150R
R124 4k7
R125 820R
R126 5k
R127 25R
R128 25R
R129 1k5
R130 22k
R131 22k
R201 R68
R202 R68
R203 R68
R204 R68
R205 R68
R206 R68
ZD101 27V
ZD102 27V
Hi Mark
I have to say, you're quite right about this amp sounding like no other. Even though I'm only using it with a test speaker, and running in mono, it is very impressive. I was listening to The Prodigy whilst testing earlier, and it just has so much control over the bottom end that it left me astounded. I haven't let it warm up for over an hour yet as I have been tweaking, but once I get the PCB stuff sorted I will give it a proper extended run and see how it develops.
I am so pleased with this amp. Much as I love Gainclones, (and I do as they do so many things right), this amp just rocks out. It is in a different league altogether. 🙂
I have to say, you're quite right about this amp sounding like no other. Even though I'm only using it with a test speaker, and running in mono, it is very impressive. I was listening to The Prodigy whilst testing earlier, and it just has so much control over the bottom end that it left me astounded. I haven't let it warm up for over an hour yet as I have been tweaking, but once I get the PCB stuff sorted I will give it a proper extended run and see how it develops.
I am so pleased with this amp. Much as I love Gainclones, (and I do as they do so many things right), this amp just rocks out. It is in a different league altogether. 🙂
Coulomb said:
I have been listening to Litz wire for ages.
This hobby can become such a passion that it derankes the other that started it.
I have become a parts and datasheet fetishist, when i go through my hump of collected articles i feel like an antiques collector.
It is good of you to remind us that it is the music that rocks the boat, not the hardware, Anthony.
Due to a slight confusion i have been waiting 2 months for the parts of my current amp thing, i thought of killing time by listening to some music.
Is he nuts or what ?
Enjoy the Litz, or Liszt, Anthony.
Regards.
2 PCBs
Hi all,
you are starting to talk really nice sounds in this amp.
Which part of the topology is responsible? or is the whole worth more than the sum of the parts?
Are there 2 spare boards for the UK?
Hi all,
you are starting to talk really nice sounds in this amp.
Which part of the topology is responsible? or is the whole worth more than the sum of the parts?
Are there 2 spare boards for the UK?
Hi Andrew
Boards will be available soon, watch this space...
As for your questions about the topology, I honestly don't know why this amp sounds so good. The Class A design, and simple circuit probably helps, but so does the ability to drive loads with a huge amount of current if required.
K,
All this stuff will go in the Wiki, but to save confusion between my, and the existing design I was going to add it all in one go.
Anthony
Sorry to hear you're a little disillusioned with our hobby at the moment, but your approach sounds right. Go off and spend 6 months listening to music, then come back fresh and see how you feel then. Don't make the mistake of selling up everything though, keep the few special bits that you just might not be able to get hold of again. 🙂
Boards will be available soon, watch this space...
As for your questions about the topology, I honestly don't know why this amp sounds so good. The Class A design, and simple circuit probably helps, but so does the ability to drive loads with a huge amount of current if required.
K,
All this stuff will go in the Wiki, but to save confusion between my, and the existing design I was going to add it all in one go.
Anthony
Sorry to hear you're a little disillusioned with our hobby at the moment, but your approach sounds right. Go off and spend 6 months listening to music, then come back fresh and see how you feel then. Don't make the mistake of selling up everything though, keep the few special bits that you just might not be able to get hold of again. 🙂
pinkmouse said:
IMHO, it is the low rails....
I have heard pretty bad designs sound so nice only because they were 25-50 watt amps (i.e. low rials), but as soon as you increase rails, they sound hard, bright and edgy. I do not know why this happens but I have seen it all too many times.
Designers take a same basic design and issue several models with different power ratings (i.e. voltage rails amonth other things) and you will find that the higher power version of the same circuit does not sound so good, but the lower power versions get better reviews.... look at the Denon's, the Adcoms, KSA-50 etc etc.
But I do not know WHY this happens only that I have seen this correlation all too often for it to be a coincidence...