JSX Hiss, unwanted noise and tube life issues...

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Classic30inCincy
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Re: JSX Hiss, unwanted noise and tube life issues...

Post by Classic30inCincy » Sat Dec 12, 2009 4:56 pm

CastleJoe--

Glad that all is well and JSX fixed.

Roger Crimm & Corporate Customer Service to the rescue.

Peavey truly cares.

Hope your health keeps improving...........

Jim Listerman
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corr_blimey_guvnor
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Re: JSX Hiss, unwanted noise and tube life issues...

Post by corr_blimey_guvnor » Wed Dec 30, 2009 6:21 pm

Castle, great to hear you all sorted now, I remember reading your saga a month or so back and its good to hear closure!

I do have one question, as a fellow JSX owner and a resident of the UK where the power is variable 230v +10 -6, I would like to ensure a consistent voltage to my amp and know that when the tubes are changed that the amp is set optimally. You mention a "Veratact", I cannot find any record of such a product or anything that spells/sounds similar via a google search. Do you happen to remember excatly what it is, or does anyone reading know of this type of device?

Many thanks in advance and happy new year to all on the forum!!!
Ibanez JS1000 Black Pearl Finish
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CastleJoe
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Re: JSX Hiss, unwanted noise and tube life issues...

Post by CastleJoe » Wed Dec 30, 2009 8:59 pm

Hey there "corr_blimey_guvnor"... What a cracker.. :-)

Here is the type of unit your looking for its called a Variac...

http://www.variac.com/staco_Variable_Tr ... er_Map.htm

EVH used to use one on stage like a wah... But to run his amps so hot they melted....

The idea is to get one that is inclosed and with a meter. $$$ But then the amp is going to sing...

Furman make power regulators, but these regulate power + or - 5%...But thats better than no regulation at all.

If you ever get anoid with the somewhat fizzy nature of the amp when using the Ultra channel and a little on the crunch... Swap out the noise gates diodes for LED's (A special type of LED, apparently used in Marshalls). The amp completely opens up. No more fighting those EQ knobs...

Instant satriani tone...

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corr_blimey_guvnor
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Re: JSX Hiss, unwanted noise and tube life issues...

Post by corr_blimey_guvnor » Thu Dec 31, 2009 6:07 am

Castle, many thanks for the info! Much appreciated.

Happy playing for 2010!
Ibanez JS1000 Black Pearl Finish
Peavey JSX 120 Head
Marshall 1936 Cabinet
TC Electronic G System
MXR Zakk Wylde OD
Marshall Bluesbreaker MK2
Boss F500L Exp Pedal
Jim Dunlop Dimebag Cry Baby Wah from Hell

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by manfromplanetx » Sat Jan 09, 2010 10:23 am

Hi guys... long time since I posted on here...
I have read though this post and am glad that both the amp and, most importantly, the player are doing well.
I know I may be asking the impossible here but any idea what happened here...

We then tested with effects through the loop.... There was noise being introduced through the loop... He went back to the schematics had a think... Powered down changed some components from the main board...

I plugged back in with effects back in the loop and I kid you not... I nearly creamed my pants.... Not sure exactly what he did... but let me tell you my JSX sounds absolutely amazing now... Better than ever...


and here...

- As far as the fizzy sound I could hear in my tone was to do with diodes in the amps signal chain. These were swapped out for an alternative component. The difference to the tone, that is elimination of fizz was night and day. I have no idea which ones were exchanged? But my tone now is amazing. No more fighting the amp to achieve an awesome tone.

from what I read and understand from the schems I have seen on the ultra circuit this is how I see this went down.

V1 2 and 3 were noisy enough to over drive the noise gate to cause the hiss and or rumble ( I have heard brand new EH 12ax7s that sound like a Saturn 5 taking off in a high gain ultra circuit)

The bias was not set as Roger Crimm describes here ( I looked for that web site that was a response to another rant about the EL34L tubes in this amp I will post if I can find the damn thing) any way it basically said use the test points on the back of the amp on a DC meter and adjust it the bias pot with switch in EL34 mode to 42.5 volts. Looks like though the common value reflected after using a bias probe is 41-41.5 V, aaa...aanyway I digress...

At that point it looked like most of the noise problem was fixed until they tried the loop, which looked like, if I guess right from previous experiences , required some form of OP amp or other component repair like coupling caps or a noisy resisitor.

Then it appears they either eliminated or replaced the noise gate diodes with something, which fixed the fizzy issue.

I just purchased a used JSX and am curious about these items and potential upgrades to the:
effects loop
noise gate
the correct way to bias this thing

Just to provide some backround since all of my previous posts from the old forum are long gone. My main amps have always been Peavey I have owned:Triple XXX, Backup VTM, couple of backstages, a duece (my first amp), Bandit112, Classic 100 head and a Rage... all either blowed up or sold
I still own: JSX, VTM, 5150 script, Ultra Plus, Tubefex/50-50 power amp, Classic 50, Classic 30, Classi 20, Ultra 112, TripleXXX EFX, and a Wiggy.

My favorite tones come from the Tubefex Lead channel, the VTM dimed, the XXX40 Crunch with EL34 dimed, and the blessed Ultra Plus, and I am working on the JSX hopefully to get the crunch to the crunch XXX40, Ultra plus and then a little more using EL34s. tone is always hard to describe. The JSX I purchased still has the tubes that came in it output 5881wxt and who knows what preamp tubes, it sounds great already, but... oh well I will shut up now and see what kind of responses happen here....

thanks
mpx

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by manfromplanetx » Sat Jan 09, 2010 7:16 pm

Bias ... I did find the values in the FAQ at the top of this forum, so that answers that question, although there are some refs and a post here that uses the eurotube ma draw method, which niether would be the scope/sine wave method that really is the (in my mind) way to stop crossover distortion in the output section in an AB amp if needed or reccomended by the mfg. My favorite new method that I 'heard' of setting the bias is setting it by ear... oh my!!!
So I am going to develop my own method of biasing the output tubes by leaving the amp on and laying bacon across the output tubes and measuring the amount of time it takes to cook with the master volume at 12 oclock a 500mV sine wave at the input with the clean channel on and all of the controls on that channel all the way up. For the bacon I am going to use Oscar Mayer Center Cut bacon, not the thick cut, to keep down the grease factor, and for the EL34s, shoot for a cook time of about 15-20 minutes. That way I have bacon goodness and tone all at the same time. Once I have established a baseline then I can apply that to different types of output tubes and amps.

(please ignore the technical content of this post and dont try this at home)

mpx

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by Classic30inCincy » Sat Jan 09, 2010 9:25 pm

mpx must be related to e-merlin...........

They both loves their bacon.

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by manfromplanetx » Sat Jan 09, 2010 11:16 pm

Yo Cinci...
I live about 40 miles North and slightly west from you
;)

mpx

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by Classic30inCincy » Sun Jan 10, 2010 8:24 am

Guessing........North By Northwest = US Route 27 = Liberty / Richmond Indiana Area.........

Close.......????

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by manfromplanetx » Sun Jan 10, 2010 11:38 am

actually englewood ohio... north and west of Dayton which makes it NNNW
howdy nieghbor

mpx

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by Classic30inCincy » Sun Jan 10, 2010 12:52 pm

Howdy........I was close!!!!

Between US RT 127 and I-75 in Ohio

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CastleJoe
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Re: JSX Hiss, unwanted noise and tube life issues...

Post by CastleJoe » Fri Jul 09, 2010 7:48 pm

Hi All,

I thought it might be worth letting everyone know, tube life seems to be good again. 8 months. COuld be a little better, but Im real happy with the amp now. And the fixes have appeared to fixed a few issues I had so all is well.

Im going to fit some Mercurry Magnets in it next. Starting with the output transformer and a choke in place of the resistor on the board.

Listens to that and then see what differnce replacing the 4 rectifier diods with freds will make. Its ment to improve the sustain of the amp X2. But I dont want to effect the tone so well see.

Im also going to experiment with the filter caps. Ive heard by changing them from 60vdc to 100vdc caps things become very quiet? Again well see and if I dont like it Ill have the original caps put back in or some caps of better quality at the original values.

Ill keep you all posted. If youve tried any of these changes feel free to give me a heads up...

Cheers Guys... :D

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by odgeuk » Tue Feb 08, 2011 3:14 am

CastleJoe wrote:Hi All,

I thought it might be worth letting everyone know, tube life seems to be good again. 8 months. COuld be a little better, but Im real happy with the amp now. And the fixes have appeared to fixed a few issues I had so all is well.
8 Months? Are you gigging?

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by odgeuk » Tue Feb 08, 2011 3:24 am

Classic30inCincy wrote:Read The Reviews At The Tube Store.....
Personally will never use EH tubes again.

Brittle and prone to microphonics.

Serve OK as fishing float when removed from amp.


Do you mean the 12AX7? or EL34? The product blurb at Tubestore for the EH 12AX7 is quite complimentary:

"The 12AX7-EH tube has a nice balanced sound, a very low noise floor and excellent performance in terms of microphonics. The lack of microphonics may be due in part to the return of a shorter plate structure or better materials. I've had some samples that were tried in various amp stages. Pre-amps, tone stacks and phase inverters, a winner in every location...I have used the EH to successfully tame amps that defied all other attempts to kill microphonics and unwanted feedback. This tube is a winner, buy 'em and try 'em, they may be just the piece you've been looking for."

Makes me wonder if we can trust the reviews, the EH 12AX7's in my Peavey Classic were dreadful and a move to JJ's was a vast improvement in reducing noise.

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Re: JSX Hiss, unwanted noise and tube life issues...

Post by nassos » Mon Apr 18, 2016 5:51 pm

Hi to all from Athens!
I just read all the posts trying to fix a JSX....It has some issues like click noise when switching from crunch to clean and volume problems on crunch/ultra channels...What I mean is when I turn the volume knob at zero does not shuts down the signal....Only when I turn the gain knb at zero!!! Strange a bit eh?...Any suggestions?

Thanks in advance!

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