K16LS Amplifier Mods
zingo
Posts: 11,258
After having the K16LS amplifier from S5 Electronics for 5 months, I have been enjoying it. It's a great build and pretty good quality as well. I did realize however, that is has a bit of a hum that is pronounced when the amp is turned up over half way. This isn't a problem for normal listening, but is something that I want to take care of none the less.
So I have decided to do a few mods to the amp this week, and I'll let ya'll know how it turns out. The first plan of action is to install a 0.01 uF cap across the HV transformer leads. This should remove the hum, or at least most of it if that is the cause.
The next mod will be installing 270k bleeder resistors on the filter caps. I am almost just doing this mod because I can, and because it won't really cost anything.
The last mod is to install new, higher quality filter caps with larger values (220uF, 220uF, and 100uF instead of 220uf, 100uf, 22uf). This should improve the sound quality a little.
One question I have is, has any of ya'll used Ruby Gold axial capacitors? PE has them and they appear to be a premium cap at a good price, but I can't find many reviews of them or info on them. I think I'm going to use them for the filter caps, unless there is a strong reason not to.
I'll update ya'll with progress as I make it, and pray that I don't kill myself with high voltage. :eek::p:eek:
So I have decided to do a few mods to the amp this week, and I'll let ya'll know how it turns out. The first plan of action is to install a 0.01 uF cap across the HV transformer leads. This should remove the hum, or at least most of it if that is the cause.
The next mod will be installing 270k bleeder resistors on the filter caps. I am almost just doing this mod because I can, and because it won't really cost anything.
The last mod is to install new, higher quality filter caps with larger values (220uF, 220uF, and 100uF instead of 220uf, 100uf, 22uf). This should improve the sound quality a little.
One question I have is, has any of ya'll used Ruby Gold axial capacitors? PE has them and they appear to be a premium cap at a good price, but I can't find many reviews of them or info on them. I think I'm going to use them for the filter caps, unless there is a strong reason not to.
I'll update ya'll with progress as I make it, and pray that I don't kill myself with high voltage. :eek::p:eek:
Post edited by zingo on
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Are the filaments heated by AC or DC?
Oh, and don't let your home insurance know you have an electronics device in a wooden box. -
Thats a neat looking little amp,did the kit include the tubes and transformers?.(Are those EL84's?).Hopefully your mods take care of the huuuummmm.
Good luck and stay safe.;)Testing
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The filaments in the amp are heated by AC I believe ShinAce, and I looked at many metal chassis, but decide to go with wood for the look and ease of modification. Plus, I don't have to ground the chassis!
GV, the outputs are cheap 6005 tubes (variant 6AQ5) which maybe similar to the EL84(variant 6BQ5). Do you think they're swappable? -
Yeah no worries about nuking yourself if one of the high voltage wires contact the chassis.Plus, I don't have to ground the chassis!
Sorry zing I don't know,youll have to ask one of the resident the tube gurus.GV, the outputs are cheap 6005 tubes (variant 6AQ5) which maybe similar to the EL84(variant 6BQ5). Do you think they're swappable?Testing
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Upon a little more research, I don't think so; similar yet different enough. I may try some 6AQ5s instead of the 6005s thought.
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Any update Zingo?I like speakers that are bigger than a small refrigerator but smaller than a big refrigerator:D
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I haven't tried any new tubes, as I figured I would just roll them when the old ones wear out. The 6AQ5s seem like the best match for the 6005s.
As far as other updates, I swapped out the filter caps for the Ruby Golds and put bleeders on them. It helped to reduce the hum alittle. Also swapped the cuppling caps for Daytons. I swapped out the pot for 2w resistors which lowered the noise and sparkled the highs, and rerouted the signal wires away from the transformers; while also swapping the signal wire to shielded and double twisted Canare StarQuad. I coupled that with moving out, rotating, and standing the output transformers on end, and that helped lower output hum the most. I also installed hum filter caps across the HV leads and the speaker outputs. Another step in noise lowering was adding two silicone ring dampers per tube. All these mods in combination lowered hum and ground noise, and increased the SQ. Plus, it was a great learning experience and I didn't even shock myself once!
(The amp was continually checked and tested for changes throughout modding by ear and ocilliscope.)
On the cosmetic side, I put a power LED in the hole where the volume pot was, and I will be staining the wood black to match its black plexti top.
It's a good little amp, and has pretty decent SQ with upgrades, but isn't really worth the money for what you get with all the mods included, without the experience and knowledge gained. I will be keeping this amp as my computer rig amp and can't see myself getting rid of it any time soon. It is only 16wpc, but is more than enough for my RDO Monitor 5Jrs and my office. -
Have you considered using a choke in the DC supply?The addition of one might help lower your noise floor further.Testing
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Thanks Zingo for the update.
I want to build one of these amps but it sounds like by the time you get it to sound the way you want you are into Dynaco ST 35 and 70 territory money wise. I do like the learning aspect of tweaking this amp but........
ScottI like speakers that are bigger than a small refrigerator but smaller than a big refrigerator:D -
I would probably look into something else as well. I will try to take some pictures of the finished unit later this week.
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Looking forward to seeing the pictures.
ScottI like speakers that are bigger than a small refrigerator but smaller than a big refrigerator:D -
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Dang Zingo-attracting them like flies huh?
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