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Jolida 502B question

M

mbeigh

Active Member
I just recently acquired this integrated amp as my first foray into tube amplification. It handles my Infinity RSIIIa speakers pretty well, although bass is not as good as solid state.

My question concerns the two middle front tubes (12AX7) that don't seem to light up. Am I not getting everything I should out of this amp, or should I not concern myself as the sound is pretty good. The other six tubes light up just fine.

Anyone else with this amp have a similar situation?

M Beigh
 
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That's what the original owner thought. I just wondered if he was blowing smoke northward. Hopin to hear from other owners.
 
Mine does the same thing, and I share your criticism in the bass dept. It now sits unused in favor of a tube pre amp with a ss power amp.
 
Before giving up on the Jolida. Try a set of Tung Sol 6550's or if you can find a quad of Acoustic Research 6550's (Tung Sol). Swap out the 12AX7's for Telefunkens then try a few 12AT7's. I own Jolida amps and I have found the Tung Sol / Telefunken matching to give me more bass as well as added gain/volume. EH tubes were the worst thing I could have run in my amps. Dull and lacking bass were just 2 of the things I didn't like about the tubes.
 
The original owner of my Jolida 1301 hybrid swapped out the 12x7s for a pair of NOS tubes
 
mbeigh said:
I am debating going back to my tube pre and ss amp. Anthem Pre-1 and Mac2002.
Click to expand...

Not really a fair comparison IMHO, considering the retail cost of these components. You were expecting the stock Jolida 502B to sound better?

The Anthem Pre and Mac SS amp have several advantages over the Jolida. The Anthem has a discrete power supply, more linear tubes, and possibly a better circuit topology (can't find a schem.), than the Jolida's 12AX7/SRPP front end.
The Mac will have a huge power supply/damping factor compared to the Jolida.

Having said that, the Jolida 302/502B's are good enough to deserve a thorough upgrade, and decent NOS signal tubes and good current production/NOS output tubes. These amps have great modding potential, and an easy way to learn how tube amps work by doing the mods yourself.

Jeff
 
This amp has already received a level 2 upgrade from underwood hifi. Eh 6550 power tubes mullard 12AT7 and EH 12AU7.
 
mbeigh said:
This amp has already received a level 2 upgrade from underwood hifi. Eh 6550 power tubes mullard 12AT7 and EH 12AU7.
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I have the same exact tubes, still not very happy with this unit. I did see an improvement when I used my tube pre and the Jolida as a power amp. I set the volume on the 502 at about 1:00 clock and used the pre amp to control the overall sound level. You should try that, any input on the 502 will work.
 
Thanks, that did change the sound. Little more bass, little more laid back. I'll listen this way for a while.
 
mbeigh said:
This amp has already received a level 2 upgrade from underwood hifi. Eh 6550 power tubes mullard 12AT7 and EH 12AU7.
Click to expand...

So the two tubes in the front center position are EH 12AU7's, not 12AX7's that the stock amp would use? This would explain the "not lighting up" comment that you made in your original post. I have a preamp that uses 12AU7's, they don't "light up" like other tubes.

For starters, I would swap out the crummy EH 12AU7's for NOS Sylvania JAN 6189W's. These are equivalent to 12Au7's, but sonically superior to the EH's. If you like what you hear, the next step you be to follow builder's advise and ditch the EH 6550's in favor for the Tung Sol's.

I find it strange that someone would take the amp this far and not put decent tubes in it. If it's got Mullard 12AT7's, why not go the extra distance with the other positions.

Maybe give Jim McShane a call, he's a great guy, very knowledgeable and may have other tube recommendations.

Jeff
 
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