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K-502 Report [message #8570] Fri, 26 November 2004 07:54 Go to next message
GarMan is currently offline  GarMan
Messages: 960
Registered: May 2009
Illuminati (2nd Degree)
Three weeks ago, someone on the SET forum asked about kits and I recommended the K-502 kit from AES, based on positive feedback on the net. The thought hits me, why don't I get one too? It's not very expensive and the Cdn dollar's doing very well right now against the $US. Three weeks later, it arrived yesterday at my door.

The package was packed very well. The kit box was shipped within a larger box. The kit itself was a lot smaller than expected, with the breadboard being no more than 9"x7". To anwser the question on everyone's mind: yes, they are shipping with ceramic sockets now. No need to worry about the infamous "melt-down" that's frequently described. The PCB itself is of good thickness and strength, but the trace on it seems thin.

For anyone who has building experience and is looking for a fun and challenging project, this in NOT for you. There's really nothing to completing the kit. To make it fun, I tried to put together as much of the kit together as I can going only by the schematics. I only missed one piece and that was because it was labelled differently on the PCB. Perfect kit for beginners or children with supervision.

Sockets were soldered on the proper side of the PCB with all components soldered on the underside. Did this on purpose because I eventually want to mount the PCB underneath a chassis top with the tubes exposed on top. The only components that could not be soldered on the underside were the bridge rectifier and pot, but that's no big deal. The bridge is small enough to hide under standoffs while the pot will eventually be chassis mounted.

It took under an hour to stuff the board and another half hour to attached the transformers to the breadboard and PCB. The toughest part was figuring out the powercord and switch. The kit requires you to splice a thumb-wheel switch onto a powercord. This will be the first thing to be replaced.

Enough talk about the build. How does it sound? Very good. If you factor in the price of $150, AMAZING! Compared to my ASL KT88 PP, which has a MSRP that 10x more than the K-502's price, it still sounded like a decent amp. The K-502 does sound harsh and grainy when pushed but can still drive a set of JBL 2235's to high volumes. That was the thing that really surprised me, that it was able to handle these cones. Bass was rolled off, but the deep bass was still there, just quieter.

One thing to keep in mind: this amp's not grounded to earth ground, so be very careful when wrapping a metal chassis around it. Also, because it's "floating", it will hum when you're using an "ungrounded" source like a Discman. The hum disappeared when connected to my tuner or CD Player, which are propered earth ground.

I'm sure everyone's aware that what you're getting for $150 is a great performing amp, but not a complete, use-it-anything-everyday component. Put a finger on an exposed lead and you will get fried. I'll probably end up spending another $100 on this amp for chassis, selector switch, new pot, input jacks, binding posts, power cord and power switch. You're still getting a lot of amp for $250. It might also be worthwhile spending another $20 to replace all the coupling caps too. These things add up and its easy to inch up to a price point where there are some very compentent kits at the $500 mark.

Gar.


Re: K-502 Report [message #8571 is a reply to message #8570] Fri, 26 November 2004 09:04 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Say Garman; have you looked at Ralph Powers 6b4g PP amp? It uses Dyna Iron. I have been looking for something to build for a while; hence the KT 88 posts but this supposedly sounds very good and I have the Iron. I only bring it up because I know you too were looking at KT 88's.
It is transformer interstage coupled making it somewhat easier to build.

Re: K-502 Report [message #8572 is a reply to message #8570] Fri, 26 November 2004 11:50 Go to previous messageGo to next message
paba is currently offline  paba
Messages: 21
Registered: May 2009
Chancellor
Thanks for this report. Great timing, my younger brother needs amplification and has very tight budget so I pointed him to K-502 based on web feedback. Now your report adds more info.

thanks for contributing
Paul

Re: K-502 Report [message #8573 is a reply to message #8571] Fri, 26 November 2004 15:19 Go to previous messageGo to next message
GarMan is currently offline  GarMan
Messages: 960
Registered: May 2009
Illuminati (2nd Degree)
I've seen that design before. Very similar to the KT-88 P/P on audiodesignguide.com. Looks to be a very easy build, but can be expensive due to the interstage transformer. They're about $85 each, aren't they?

Re: K-502 Report [message #8574 is a reply to message #8573] Fri, 26 November 2004 16:22 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Yes exactly. However Lundhal has a pair for 125$ demoe's. What's audiodesignguide? How are you thinking on the KT 88's lately?

Re: K-502 Report [message #8575 is a reply to message #8570] Fri, 26 November 2004 17:37 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18793
Registered: January 2001
Illuminati (33rd Degree)
Great review Gar, thanks!

Re: K-502 Report - pt 2 [message #8655 is a reply to message #8570] Fri, 07 January 2005 08:06 Go to previous message
GarMan is currently offline  GarMan
Messages: 960
Registered: May 2009
Illuminati (2nd Degree)
Continuation of this K-502 project can be found in the Craftsmen Forum.

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