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

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

Post by CastleJoe » Thu Oct 29, 2009 7:46 pm

Hi all,

Im from Adelaide South Australia and own a Peavey JSX head and bottom quad. Its one of the amps from Satriani's 2008 tour and signed...

When I first got the thing, I nearly jizzed in my pants it sounded that good. There was a small, I mean very small amout of noise / hiss coming from the amp... I figured it was normal as this was a high gain tube amp..

However then my wows started... Tube life was real short... I use this amp only on weekends and only for a single session of around 1 - 1.5 hrs...

My tubes are not lasting any longer than 3 -4 months... And worst of all, Im getting at least one microphonic tube within 2 -3 weeks from new set of tubes being installed and biased by a Peavey tech. or Peavey Australia..

I keep getting told that thats one of the trates of owning an all valve amp.. WTF?

Ive owned valve amps before, and have played guitar for about 30 years...

Ive only ever used JJ power tubes (EL34's) and JJ or Grove tubes in the pre-amp section... Always setup by a tech...

I have sent my amp to peavey authorized amp techs (4 of them) and all they do is re-tube and bias the amp and send it back to me.. Tone is restored for a while, but the Hiss is still there.... Every time...

The amps even been back to Peavey Australia twice.. Same deal...

Ive purchased a Furman power conditioner, Noise suppressor for the loop and a voodoo labs pedal power 2 to eliminate any ground loops in the pedal signal chain...

I was looking at buying an Ebtech Humm Eliminator next... But I come to the conclusion Im waisting my time and money...

The Hiss remains, even with the JSX's gate at 10. And tube life is still short..

The amp never sits on top of the quad to try and help sustain tube life.. I was told by a one of the techs this is why my tubes life was so short.. He wouldnt belive me, when I said the amp is always on the FX rack not the quad...

Ive found preamps make a huge difference to the level of the Hiss....

What is going on.. ????

Ive read an artical that suggests the main pcb in the JSX is rated at 63vdc but the Filter Capacitors installed are only rated at 60vdc... This means as the tubes start to age and draw a little more current we are going to have a problem... And you know what the Hiss gets louder as time passes...

This guy then replaced the 60vdc caps with 100vdc caps and claims that all the hiss from the amp is gone... Even at high gain and levels.. completely silent...

Doses anyone know anymore about this? Im think of trying it to get rid of the hissing...

The tube life thing? any ideas? I mean if Peavey Aust cant even bias the thing correctly, who can? So I dont think this is the case.. I feel somethings gone astray in the amp..

Im not a tech.. Yet Peavey Australia expect me to tell them whats wrong with it.. Because I cant they just tell me its fine and send it back...

This is really starting to pee me off to say the least.... Whats the point of a 5 year warrenty?

Does anyone think the screen grid resistorst could be affecting my tube life, maybe? Ive heard the JSX has problems with them..?

Peavey (US) if your reading this please contact me, I need some assistance and a positive outcome...

Ive been fighting cancer for the last year and dont need this greaf... Music is all I have at the moment...

Well Im now getting ready to take the amp to a tech again for its 6 -7 re-tube in 2 years...

Wish me luck..

Cheers...

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

Post by Classic30inCincy » Thu Oct 29, 2009 8:20 pm

Pre-Amp Tubes Are Extremely Important To Solve Noise Issues......

One of my Classic 30 112 combo's went into shop and tech recommended ALL JJ Tubes including pre-amp & power tubes.

Personally not satisfied with the performance...........

Tone not what I wanted and a constant noise issue.

Research led me to using mixture of make & model pre-amp tubes that work best with my amplifier.

ALL JJ ECC83S pre-amp tubes no longer!!!!

Position V1 Clean Channel = TungSol 12AX7 Re-Issue for exceptional tone and quiet operation.

Position V1 is extremely critical since it forms 85% of your amplifier's tone.

Position V2 Overdrive can be any number of different tubes (including the JJ ECC83S) since it is used only when overdrive is engaged to "overdrive" the clean channel tube in Position V1.

Position V3 Phase Inverter provides the remaining 15% of tone AND collects signal from V1 Clean to channel into power tubes.

A noisy tube in Position V3 will drive you crazy.

Found via research the Sovtek 12AX7LPS large plate spiral filament to have low noise characteristics and it works as advertised in the Classic 30.

Would recommend you acquire:

1 pc TungSol 12AX7 Re-Issue for Position V1

1 pc Mullard 12AX7 Re-Issue or JJ ECC803S Large Plate for Position V2

1 pc Sovtek 12AX7LPS for Position V3

Try this combination and see if it helps you.........

Excellent Website To Research Pre-Amp and Power Tubes:

http://www.thetubestore.com

PAF Classic Series Tube Kit.......Created By Classic30inCincy
Majic Mojo Tradename..........Created By Classic30inCincy
Graduate Of Joe Friday / Dragnet School Of Correspondence
Doctorate Degree Diplomacy From Royal Order Possum Lodge

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

Post by CastleJoe » Thu Oct 29, 2009 9:57 pm

Thanks for the Pre-amp tube info..

Cheers...

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

Post by CastleJoe » Thu Oct 29, 2009 10:49 pm

You know there is only one Tech here in Adelaide that I trust.. And thats Frank from FM Audio...

When he does a bias on an amp its gold...

Im hoping he can help me work out whats going on with this thing..

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

Post by Bertotti » Fri Oct 30, 2009 1:21 am

I would email or call peavey US also. email may ae a few weeks to hear back from. Also I think the JSX has four pre tubes. So V4 would be the same as Cincy's V3. think.
Creativity is doing something weird and finding out others like it!

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

Post by CastleJoe » Fri Oct 30, 2009 2:27 am

Yeah, thats right.. V1 common input valve, V2 Crunch and Ultra valve, V3 split into A: Cruch / Ultra B: Active EQ, V4 is the phase inverter. From memory...

I like the JJ EL43's so Im going to stick with them... Pre-amps is going to be tricky..

Im thinking of trying JJ ECC803S's in V1 and V4. I like the EH in these positions because they realy chime...But there to noisy.. Any other sugestions for these two positions would be awesome... The Sovtek 12AX7LPS in V4 and a Tug Sol in V1 is something to think about also..

Going to stick with ECC83S's in V2 and V3... They sound awesome... But like Cincy said.. V1 is what influences everything else.. And I dont want to run a dark sounding tube like the ECC83S here...

Whats the Tung Sol sound like?

Also anyone heard about the Filter Caps mod? I understand FJA do change these caps when they mod the JSX....

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

Post by avirox » Fri Oct 30, 2009 7:42 am

Yeah it's a noisy amp, but I suppose that is just the nature of the beast. I recently got my JSX Combo back from the techs, myself (they *hopefully* fixed a power issue which was causing weird buzzing with the reverb). Unless you're running the master volume past 5, the noise is never really that bad/noticeable on either of the 3 channels.

As for the lifespan of the tubes, my JSX has JJ's in it and supposedly they're from 2006 (I gleaned this from the stickers on them..). The amp sounds fine to my ears and really punches through everything I've ever played before, slight noise aside.

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

Post by Classic30inCincy » Fri Oct 30, 2009 8:31 am

Read The Reviews At The Tube Store.....

TungSol currently the highest rated pre-amp tube for musical ability and low microphonics.

Personally will never use EH tubes again.

Brittle and prone to microphonics.

Serve OK as fishing float when removed from amp.

See the pre-amp tube review to better understand.

Chart used to measure capabilities scale of 1-5.

TungSol at top...........

For V1 consider TungSol or the JJ ECC803S.

Have an ULTRA 60 112 combo equipped with JJ ECC803S in V1 and V4 and tube made great improvement in tone AND cut noise via phase inverter to zero noise.

PAF Classic Series Tube Kit.......Created By Classic30inCincy
Majic Mojo Tradename..........Created By Classic30inCincy
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electroman
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Re: JSX Hiss, unwanted noise and tube life issues...

Post by electroman » Fri Oct 30, 2009 9:28 am

Hello
Hello

I work part time at a repair shop and I handle warranty/non warranty repairs for Peavey, Marshall, Mesa, Vox, Fender(reg Fender Gold Tech) etc.
So I do alot of tube changing and biasing.

Anyway from what I have seen JJ tubes have one difference that is their pins particularly on the power tubes are thinner than that of other tube producers. When ever I am installing JJ pre or power tube I always clean and tighten the tube sockets. Secondly I have a JSX as well and when biasing the amplifier I always use a bias probe I do not go by the voltage output connectors on the back of the amp. In the EL34 mode depending on the brand or set of tubes you can over bias the tubes at the -42.5 volts Peavey recommends. I have seen it first hand with JJ tubes and some Winged C's. The 6l6 mode is ok, its actually set a little on the cold side even when cranked to max.

If your tech is using the supplied measuring connectors on the amp and not a bias probe you could be over biasing the tubes causing them to run really hot. This will kill them very fast and they will get noisey. The hotter the bias the more"shhhhhhh" you will hear from the speakers as the tubes are idling at a high level and will produce noise.

I work in industrial electronics and am curious are you 220v or 240v for your ac outlet at home?? Your tech should check to see if you have the proper power transformer for your area as this can also cause internal voltages to be out of spec which will kill your tubes fast. The plate voltge (B+) for the JSX should measure around 480vDC.

Good luck

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

Post by CastleJoe » Fri Oct 30, 2009 5:58 pm

All Awesome Info... Thanks...

I am going to try the Tung Sol in possition V1...

Yeah the tech that I use, uses a scope when biasing the amp to find the sweet spot. Sounds awesome at first.. For maybe 2 -4 weeks, then things start going wrong...

The Hissing in the amp, yeah its normal to a certain level because its a high gain amp.. But mine Hiss's like a snake, even on the clean channel with the master as low as 1. And a noise gate in the loop.

I also run a voodoo labs pedal power plus 2 for my pedals to make sure I dont get any ground loops..

I also run a Furman power conditioner that powers the amp..

The amp has a switch at the back that you can select between.. 220v or 230v-240v...

Power outlets in Australia are rated 240v 50 -60Hz... So all is good there...

I didnt know that the JJ pins are thin in comparison to other tubes... Hey what do you guys think abou the Winged "C" EL34's? Anyone running them? There ment to be the best of the best? Or the difinative EL34...

Hey "Electroman" so when biasing the JSX how much disapation should be considered to keep the Hiss down to a min..??

The last people to bias the amp were Peavey Aust..and Ive got a feeling its running hot.. Ive also been told if the tubes are biased to cool the tube life is affected? I suspect this is the same if your to hot as well?

Im going to order a Weber BR2 bias probe.. So I can keep an eye on the amps bias. So I can document whats going on with it.. And hand that to Peavey...Only because they dont seem to think theres an issue.. And thats because.. put a new set of tubes in there bias it, and presto it sounds great for a while...but not long.. Hiss is bad again after a week or so.. Then the tubes start falling appart..

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

Post by Van Noord » Fri Oct 30, 2009 6:26 pm

It's key to ensure your tech is not biasing the amp with the test points on the back of the amp.

I find hiss can slip through when only using a noise gate in the loop with the JSX. You should put the gate in front of the amp. I also recommend the Boss NS-2 hooked up in the x-pattern method to rid your amp of hiss and noise from both before and after the preamp.

I've never used JJ power tubes, but I do use their preamp tubes in the V1 and V2 spots. I have heard if some inconsistency with their power tubes over the last few years. I've had great results with Russian power tubes in my amp so try some Svetlana, EH or Sovtek.

I'm curious as to where the send and return dials are set on your amp.
I know with mine, having one or both set too high can result in added noise.

Also, be sure you don't have any the crunch or ultra channel eq dials set too high. These eq's are active, so the higher you set them the more output, gain and subsequent noise is added to your signal. However. cutting them too much will choke off those same results. So try keeping them no lower than 3, and no higher than 8.

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

Post by CastleJoe » Fri Oct 30, 2009 6:59 pm

Thanks "Van Noord"...

Yeah never bias via test points... a scope is used...

Ive tried the x config with my NS-2 also.. It stops most of the Hiss... But as soon as you start playing, the gate opens and you have this lovely mix of your tone with Hiss...Not good...

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

Post by CastleJoe » Sat Oct 31, 2009 5:16 am

Just found out if the pre-amp tubes are not the cause if lots of Hiss, you should check out to see if the Plate Resistor is starting to fail.. Signs of a failing plate resistor are Hissing and random crackiling and pops...

You know what... My amp does exactly these things... Sounds like a faulty guitar lead crackiling or some thing.. Just some times out of the blue... I couldnt work out what was going on..

But chances are the Plate Resistor might be on its way out.. Could also explain tube life issues as well....

holly crap...

Guys I need a schematic for the JSX, has anyone got one? Need to look into this a little deeper...

Thanks in advance... And Cincy, thaks for the tube store link.. Thats where I found this new info...

Awesome... :D

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

Post by avirox » Sat Oct 31, 2009 6:06 pm

Just to check: what are the effects loop knobs set at in the back of your JSX? I don't use anything in my loop, but i did find that even when nothing is plugged in that I can get rid of some hiss by tweaking the knobs. You should check it out if you have not done so already..

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

Post by CastleJoe » Sat Oct 31, 2009 6:22 pm

Yeah the loops can be set anywhere the issues are still there. For example:

Send: Return:

5 5

2 8

3 7

7 8

The results are pretty much the same... In rgards th Hiss...

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