pete_mac Posted January 30, 2011 Posted January 30, 2011 I thought I'd post a few pics of the Kenwood KA-6100 amp that I picked up before Christmas. It's a nice little amp with 2 x 50WRMS and the transformer has separate windings for each channel, hence the 'dual power supply' moniker on the front panel. It's certainly not quite the same as my Sansui AU-517 which is more of your traditional 'dual mono' layout. The KA-6100 was purchased with a minor fault that was easily rectified by my father (skippy124) in a matter of minutes. Since then, I've listened to it in standard form for a little while here and there. It sounds nice enough, but I find it a little bit more 'in your face' than my Sansui AU-517... not quite as musical. I guess it also comes down to my speakers - my Ushers and Sound Dynamics are both fairly forward in the upper midrange and treble department! I always intended on recapping this unit, as I loved the look of it, especially with the dual power meters on the front. I felt that the sound could hopefully be improved by refreshing the internals and possibly upgrading the size of the power supply filter caps from 4 x 6800uf to 4 x 8200uf or thereabouts. Here's some pics of the amp: Here's the nearly finished main amp board - Panasonic FC & FM (dark blue/black), ECA (bright electric blue), ECQ (brown/orange) and NHG (black) caps, and a bright green Nichicon Muse bipolar. The two small tantalum caps were replaced with Panasonic ECQ stacked film caps which are more reliable and cleaner-sounding. As with most new capacitors, they are noticeably smaller than the originals due to improvements in electrolyte formulation and construction quality, so sometimes the smaller capacitors have to stand up off the boards due to the lead spacing. No biggy. I also have a bunch of Elna Silmic II caps to go onto the preamp board which is mounted on the rear panel of the amp. I will get to this in the coming weeks. Here's the big power supply caps that I will tackle soon: I also hope to upgrade the standard speaker terminals to proper binding posts. The standard items have seen better days! I'm really looking forward to finalising the restoration and seeing how this puppy sings!!
skippy124 Posted January 30, 2011 Posted January 30, 2011 Looks like a good days work there!!! Will be very interested to hear your opinions on any improvements after the cap replacement has been completed.
pete_mac Posted February 18, 2011 Author Posted February 18, 2011 Back to the workbench! (aka wife's dining table with a towel over it for protection ) Front and rear panels were removed for easier access to a few fiddly caps on the main board, along with the pre-amp on the rear panel. The pre-amp is now devoid of blue Elnas, with nice Elna Silmic II caps throughout. All back together! Clear meter panel cleaned and polished, bias set, DC offset checked, tested on test (ie. sacrificial lamb) speakers for a few hours, and then back into my system. Sounds good so far! I have saved the main power supply fiter caps for last (as with the big Sansui AU-517) as I want to get a feel for the sound of these recapped amps before changing them. This way, I can see if any difference is attributable to them directly, rather than changing every single cap at the same time and not knowing for sure.
pete_mac Posted February 19, 2011 Author Posted February 19, 2011 Geeeez this amp sounds great through the Ushers. It drives them beautifully. I never thought I'd say this, but I'm honestly not sure what sounds better... my Sansui AU-517 or the 6100!
glennb Posted February 19, 2011 Posted February 19, 2011 good job cleaning it up there Pete, it actually looks pretty good. Would be interesting to see how these modded old units sound versus newer equivalents.
pete_mac Posted November 3, 2011 Author Posted November 3, 2011 (edited) Dredging up an old thread here, but I've now replaced the power supply filter caps with four nice 6800uf Nichicon KG Gold Tune caps, and some Panasonic 1uf film bypass caps. Old Elna caps: The Gold Tunes are snap-in caps with 10mm lead spacing, and the orignals are closer to 15mm. A bit of gentle bending of the leads and everything marries up nicely. Note that the third leg is a support leg only, so it is redundant with the new capacitors fitted. All fitted up. They sit a bit shorter but the clamp still secures them in place. Lastly, a bypass cap is added for each of the filter caps (the underside of the board and soldering etc looks a bit messy, but the solder pads for the filter caps are HUGE so you're never going to get a nice neat 'mound'. Function over form! So far, so good. I'm using it in my second system with some Usher S520s and it sounds pretty nice! The sound is more detailed in the top end than the Sansui AU-317, but it lacks a certain 'organic' sound that makes the Sansuis so good. Still, as they say, a change is as good as a holiday (ridiculous turn of phrase... I'd take a holiday over a change any day!) I'd really like to compare this amp to a newer 40-50WRMS amp which is 'detailed' sounding... it would be a VERY interesting comparison indeed. This little Kenwood does a great job! Edited November 3, 2011 by pete_mac
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