FU-19 (FM30, 829B) Single-Ended Tube Amp!

chi0001 · « **Reply #220 on:** 22 Sep 2025, 12:08 pm »

I recently purchased this amplifier and I'm considering upgrading the coupling capacitors. Has anyone here replaced them? Is it worth the upgrade in terms of sound quality or performance?

Jon L · « **Reply #221 on:** 22 Sep 2025, 03:10 pm »

Quote from: chi0001 on 22 Sep 2025, 12:08 pm

I recently purchased this amplifier and I'm considering upgrading the coupling capacitors. Has anyone here replaced them? Is it worth the upgrade in terms of sound quality or performance?

Your post reminds me to be proud of myself for sticking to "Don't fix it if it ain't broke" principal. It's amazing I have not tried to change coupling capacitors in my two FU-19 amps. I have finally learned to leave well enough alone

Perhaps you can try and let us know..

FullRangeMan · « **Reply #222 on:** 22 Sep 2025, 03:45 pm »

+1. Dont fix what is not broken.
Instead buy alternative tubes.

chi0001 · « **Reply #223 on:** 22 Sep 2025, 03:51 pm »

Thanks, Jon and Rullrangeman, for the advice! I read through all the posts and decided to order RCA 829B tubes. They're on the way, and I'm excited to try them out!

chi0001 · « **Reply #224 on:** 30 Sep 2025, 02:07 pm »

I tried both the Beijing FU19 tube and the RCA 829B, and they both sound beautiful. The FU19 has more punch, but if you can find an RCA 829B, I highly recommend giving it a try!

Jon L · « **Reply #225 on:** **Yesterday** at 03:41 pm »

Yup. This is also one of the rare tube amps that sound "good enough" with mere stock tubes

Jon L · « **Reply #226 on:** **Yesterday** at 07:53 pm »

This reminded me to fire up the amp, and yup, just sumptuous and naturally resolved music. Love it!

chi0001 · « **Reply #227 on:** **Today** at 02:16 pm »

I've noticed something fascinating: no matter which tube I use—12AX7, WE420, 6H2N-EB, or even the Beijing 6N2-Q that came with the amplifier—they all sound different but absolutely beautiful in their own way. This makes me think the Beijing 829B might be a great option, especially at just US$8.00. I asked the seller which tube pairs best with it, and they recommended the 6N2 with the 832A. Has anyone tried this combination? Any thoughts or experiences to share?