Amp, Tubes or Speakers?

Discussion in 'Tube Audio' started by Subtilty, Sep 14, 2018.

  1. Subtilty

    Subtilty New Member

    Hello! First time posting, I need some help with tubes and my setup!

    My setup is a Project Debut Carbon with 2M Blue, to a Jolida JD9 into the Jolida JD 1501 RC with until recently, supposedly GE 5751 Triple Mica Grey Plates, powering Hyperion HPS 738 speakers. All was well and good, until a couple days ago.

    The bass from my speakers started getting, not distorted, but rather cut off, and the notes sounded as if they were in a higher frequency, I am talking electronic music, like Burial and Jon Hopkins. I no longer had that chest pounding bass from the speakers from before, they go down to 35hz and are only about a few months old. Plus, at 90db with 100 watts/channel, it shouldn't be too much power. Though it is usually at 1-2 oclock, but only registers at 85db?

    I bought a cheap Boston Acoustics sub, the Micro90pv 75watts, powered and plugged it into the fixed output of my amp. It doesn't have any detail of the speakers, more one noted, but there is more bass, so it sounds better in that way. I plug out the sub at different times to hear more detail in songs, and there is even less bass from the speakers, even when the sub is not plugged in!

    There is a few pops from playing on my Chromecast randomly, but until that point, it sounded compressed. Then the higher frequency notes started to distort, and I checked the tubes, and one was burned out, so I changed one out with a different kind, and it sounded much better. The distortion of the high end and low end distortion was gone, but I still did not have any of the bass output as before. There still was no punding like before. The lower bass notes were not present.

    Could it be the speakers are blown? Could it be the amp? I bought the subwoofer around the same time I had the issues, so could that be why?

    Also, I changed the tubes in my integrated amp to GE 5751 TRIPLE MICA Black Plates, and it sounded so harsh. No detail and grainy. NOS. I want to buy the same kind I have already, but I cannot find the exact ones. I see multiple kinds of the GE 5751 Triple Mica Greyplates, but not the ones I am using. There is only one picture online and I cannot find anybody selling it or any info on it other than "Holo Getter", and that it is from the 1960s. If the are the same as the other varients, or if anybody else knows let me know, thank you!

    Sorry that was very long :p


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  2. cademan

    cademan Addicted Member

    Try and use the elimination process like connecting the speakers to another receiver or amplifier. Swap the tubes around especially the output tubes.
  3. Subtilty

    Subtilty New Member

    I have an av receiver, but that lacked the dynamics for those speakers from the beginning.

    There is an ss output stage. I tried a pair of Black plate 5751s, and a TungSol too, that and the one good Grey Plate had the dhnamics and bass there, but it was not as strong as it was beforehand, while the Blackplate was too harsh
  4. triode17

    triode17 Super Member

    The fact you mentioned compressed, says to me you may have a power supply problem in the amplifier. If the high voltage is no longer high enough, the whole amps' power will reduce. Especially the Bass, which has the most energy. Check the power supply voltages against a schematic.
  5. E-Stat

    E-Stat AK Subscriber Subscriber

    I'm with cademan on using the process of elimination. When you eliminate what is not the cause of the problem, what remains is the villain.

    That should be easy to determine. Take subwoofer out of system completely. Do the dual woofers still woof on first octave content? Remove grills and observe pistion movement.
  6. primosounds

    primosounds Powered with pure tube sounds. Subscriber

    Terra, 21st century CE
    So, your amp is a hybrid with tubes in the front and SS for the outputs?. Your symptoms could also be weak tubes which tend to sound compressed and more distorted when they are past their prime. Try and get some either new tubes or some tested strong tubes from a reputable dealer.


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