Posted by akhilesh [ 129.244.96.25 ] on May 16, 2004 at 15:11:53:
HI Everyone,
As my earlier post indicates, I purchased an antique sound USA (a now defunct company) K2003 amplifier : it uses a 12ax7 with 2 EL84s, wired in SET mode. There is -5db feedback. I got it really cheap and my aim was to: a) compare it to my zen se84C and b) to try some upgrades and see if the sound could be improved.
I received the amp in good condition, and plugged it in on a dummy load first. nothing blew up, so then i connected my homebrewed speakers to it. Here are some impressions:
1. The bass is greater than the zen by a small amount. It is also a tiny bit looser than the zen.
2. The soundstage is a little bigger than the zen's.
3. The detail is about the same, except see 4:
4. The zen emphasizes the midrange a bit more than this amp.
5. The zen has a slightly smoother sound (no negative feedback in the zen) and overall the music seems a tiny bit more "together" in the zen.
6. This amp is a lot better than my push-pull el84 amp: a lot smoother, and nicer sound stage.
7. The amp has no hum, unlike the zen which has a slight hum (the zen is tube rectified).
8. This amp gives out 4 watts of power, unlike the zen's 1.5. I suspect you can run 91-92 db speakers with this amp and get realy good sound, where the zen will be underpowered.
I opened the amp and saw the following: MIT coupling caps, and diodes with the word FR on them. Whoever built this amp already upgraded the parts. I also noticed a solen cap, along with nichicon power caps and high quality resistors. The quality of soldering was average, with many parts soldered on with not a lot of mechanical support. In fact one grounded end of a cap popped loose and I resoldered it.
Given this, as well as the small amount of room in the box, I will not be upgrading anything in this amp. The input tube is a GE 12ax7, and the outputs are sovtek. I may play around with a telefunken input tube. Overall, i am very satisfied with my purchase, given the money i paid. I would not pay $499 for this amp (the list price of the KIT alone), esp. since my speakers are fine with the 1.5 watts the zen has. However, if i has 91-92 db speakers, this amp would be much more preferable than the zen. The lack of negative feedback in the zen, along with tube rectification seems to make the music come together a little better, PROVIDED YOUR SPEAKERS CAN deal with 1.5 watts!
At the next Tulsa audio meet, i'll bring this amp for others to listen.
-akhilesh