2. amps-preamps
  3. 1172525591

Tube upgrades for Jolida 502B?

I realize this is something that has come up before, though in searching the archives I didn't come away with a clear path forward. My amp is completely stock and came equipped with Sovtek 6550s. Using it to drive Totem Forest speakers. I contacted Jolida. They recommend KT88s. Their reply is a bit unclear but they might be suggesting Electro Harmonix. They also indicate reliability issues with Chinese KT88s. Response Audio (Jolida dealer and modder) recommends Shuguang KT88s (Chinese). The Tube Store recommended JJ Tesla KT88s on the strength of their great imaging and deep bass (more bass being something I was looking for). I was initially leaning towards SED Winged "C" 6550s. Now I am a bit more confused. I'm curious about KT88 vs 6550 sonics and reliability differences. Thanks in advance to any one willing to take the time to share their experience and preferences.
128x128ghosthouse
tomtab
97 posts
 
i did call jolida about it. heres what they said. you need a y cable to plug into both inputs. then short wires to tie the negative taps together and short wire to connect the 4 or 8 ohm taps together (just the ones you are using,not both or boom) then run speaker to one set of taps. basically running the left and right speaker outs in parallel conection. also said will not get 120 watts,more like 100 this is from michael allen of jolida
wolf_garcia
6,708 posts
 
There has to be an easier way...I assume a qualified tech could put a switch in there to join the input signals, and "Underwood Wally" has been claiming the 120 watt mono spec for a while so that could make for an interesting call.
tomtab
97 posts
 
yes a mono switch on the back would be nice. then something similar to car amps for speaker connection. left channel negative and right channel positive. done!! i dont get the only 100 watt rating also. did you or anybody notice a power increase using the kt120 tubes. if you read the spec's for the 120's everybody has you believing they can make 120-150 watts a pair. im guessing thats if the amp was designed around the 120 tube to get the maximun out of them. im betting a 60 watt amp will maybe put out 70 with the 120's
wolf_garcia
6,708 posts
 
I have no way of measuring the output of my 502p, but I will say the amp with 120s seems to have a bit more headroom, and can play plenty loud in its designated space seemingly effortlessly...I never feel like I "need" more juice. New amps utilizing the extra power available with 120s seem to be coming along all the time...a Rogue Atlas Magnum now does 100 watts pc with 2 120s per side, with what I assume are redesigned trannys and such (at around twice what a Jolida costs). It is nice to have only 4 output tubes to deal with as a money (and heat) saver, and 120s are still a relative bargain.
More to discover