Is it the Jolida JD-9, or me?

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Miney

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Is it the Jolida JD-9, or me?
« on: 30 May 2009, 09:16 pm »
About a month ago I picked up a new JD-9a, hoping it'd offer a clear improvement vs. phono section of my Denon 3801 receiver.  Thought I'd perform a few tweaks before racking and enjoying, so I added vinyl sound damping inside the case (fitted around all vents), upgraded the tubes to Sovtek 12AX7LPS, and installed Herbie's tube dampers.  Vinylphool fer sher.

Sounded great! 

I go away on business returning a week later and dayum! the left channel is not pumping out the same dBs as the right!  I open it up and one of the tubes is frosted on top and cracked @ the pins.  Thinking the crack was probably a newbie mistake, I re-installed the original EH tubes and again, it sounds great.

Again I go away on business returning a week later... and dayum! same tube is fried again!  This time I when replace the tube, I also remove the dampers and try a different pair of interconnects. 

Guess what I came home to last night.  Dayum!

I've check all the switches and connections every time and all seems per the user manual.  Dip settings on the JD-9a @ 47K ohm, MM low gain output. 

Low output connection to the aux input of the receiver.  Grounded from the TT to the 3801 to the JD-9a.

TT is a clay packed Technics SL-QD33.  Cart is an Ortofon OMP-20 from KAB (LOAD IMPEDANCE: >47kOhm, 200-500pF).

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What am I doing wrong?

TheChairGuy

Re: Is it the Jolida JD-9, or me?
« Reply #1 on: 1 Jun 2009, 06:33 pm »
What am I doing wrong?

Probably nuthin' at all.

But, I'll let the technically more adept give you possible reasons for the frying factor :( and or how to fix it DIY (if such options exist)

John

orthobiz

Re: Is it the Jolida JD-9, or me?
« Reply #2 on: 2 Jun 2009, 12:18 am »
Cross post in the tube-o-phile forum...

paul

mikeyvsmichael

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Re: Is it the Jolida JD-9, or me?
« Reply #3 on: 2 Jun 2009, 06:20 am »
could it be some overheating related issue?  have you tried working backwards, step-by-step, with you mods.. ditch the  tube dampers, personally I never liked them... and then whatever you did to the case.

Not to sound like smart-ass.. but did you even listen to it without your home-brew mods?

Miney

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Re: Is it the Jolida JD-9, or me?
« Reply #4 on: 2 Jun 2009, 12:48 pm »
Quote from: TheChairGuy
Probably nuthin' at all.

But, I'll let the technically more adept give you possible reasons for the frying factor  and or how to fix it DIY (if such options exist)


Thanks John.  I spoke with Jolida; they think it's "gassy" tubes as only 7 volts are flowing through them. 

Quote from: orthobiz
Cross post in the tube-o-phile

Thanks - now that I've engaged Jolida I think I'll follow that route.   This thread can be ignored or dumped.

Quote from: mikeyvsmichael
could it be some overheating related issue?  have you tried working backwards, step-by-step, with you mods.. ditch the  tube dampers, personally I never liked them... and then whatever you did to the case.

Not to sound like smart-ass.. but did you even listen to it without your home-brew mods?

Appreciate the response.  No offense taken to your questions; I'm open to the possibility I'm a dumb ass :lol:.  If I screwed it up, I (and others here) might learn from the experiment.  They aren't "home-brew" mods though - I tried simple existing ones. 

Yes I connected and listened to it before doing the mods, but did not wait a week to see if a tube would blow - is that common?  and yes I did not put the Herbie's damper back after the first incident (note it's still on the right channel tube, which has never blown).  I also tried different interconnects the second time.

As for the damping material, I have not removed it yet.  If I opened my unit it'd look pretty much like this....



Source of pic and "inspiration" for the case dampening from this article.

Thanks all for trying to help.

TheChairGuy

Re: Is it the Jolida JD-9, or me?
« Reply #5 on: 2 Jun 2009, 03:24 pm »
Another pig-slop job from you, Paul/miney.

One of those strips is off by at least 1mm in width across the expanse :lol:

John 8)