Hi 2out2sea
I think you may need to try different tubes with that Jolida 502B. I agree with Donjr that you should ask Jolida for their input as well.
Here are my findings with tube rolling with my Jolida 502P which I think may be comparable to the 502B. This was with my system so YMMV.
For thicker bass and very clean tones I found blue glass JJ KT88 tubes paired with Mullard CV4024 and JJ 5751 preamp tubes did the trick.
I found with the Tung Sol KT-120s Preferred 7025s and Penta Labs 12AT7 tubes I had very good performance in the mids and highs along with tight bass. Lots of nice separation and detail.
My favorite overall sound was with a NOS JAN GE 6550 quad JAN GE 12AT7 and 5751s. These tubes were expensive but man the music was awesome in my system. I had a very hard time giving these tubes back to the gent that loaned them to me.
My least favorite combo was with black solid plate Penta Labs KT-88 tubes with reissue Tung Sol 12AT7 and reissue Mullard 12AX7s. Bass wasn't as tight and sound was flat to me.
Again these were my findings I'm sure others have had different experiences.
Sorry if this is a duplicate response. I tried to post my Jolida findings yesterday but I didn't see the post this morning.
I think you may need to try different tubes with that Jolida 502B. I agree with Donjr that you should ask Jolida for their input as well.
Here are my findings with tube rolling with my Jolida 502P which I think may be comparable to the 502B. This was with my system so YMMV.
For thicker bass and very clean tones I found blue glass JJ KT88 tubes paired with Mullard CV4024 and JJ 5751 preamp tubes did the trick.
I found with the Tung Sol KT-120s Preferred 7025s and Penta Labs 12AT7 tubes I had very good performance in the mids and highs along with tight bass. Lots of nice separation and detail.
My favorite overall sound was with a NOS JAN GE 6550 quad JAN GE 12AT7 and 5751s. These tubes were expensive but man the music was awesome in my system. I had a very hard time giving these tubes back to the gent that loaned them to me.
My least favorite combo was with black solid plate Penta Labs KT-88 tubes with reissue Tung Sol 12AT7 and reissue Mullard 12AX7s. Bass wasn't as tight and sound was flat to me.
Again these were my findings I'm sure others have had different experiences.
Sorry if this is a duplicate response. I tried to post my Jolida findings yesterday but I didn't see the post this morning.