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PostPosted: Mon Aug 09, 2010 6:10 pm 
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Mark IV

Joined: Sat Dec 30, 2006 11:18 am
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I posted a while back about the Stiletto Deuce II I bought from Mesa Hollywood and returned 3 times for bad tubes and finally they issued me a refund (after yelling at Petaluma guys, etc.)

Now I think I used the same cable (I have 3 spkr cables right now) on one side of my Rivera S120 with masters running @ noon @ 120 watts of power. Now the JJ E34L (which are max a few months old and I only crank max once a week nowadays) are sounding lifeless all of a sudden.

I remember the ohms on the back of the spkr jack of the amp (one of the jacks) did not match exactly the ohms of the Marshall cab input (it was 8 --> 16 IIRC). So the amp was at 8 and cab at 16 which according to mesa manuals is ok to do (8 amp --> 4 cab is bad!)

Is it possible this core x2 spkr cable is bad and how can I test it? It worked fine at the studio and no shorts, pops, etc. I haven't had too many issue with eurotubes JJ's at all...

Maybe it was the settings on my amp when I played at home after the studio jam. I did notice that the KT77 side sounded louder than the JJE34L side when I played at home after studio jam. less headroom with exact same settings, cables, etc.? seems like a power tube issue.

Any good spkr cables to recommend? I have a Monster pro that seems ok so far...

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PostPosted: Tue Aug 10, 2010 12:24 pm 
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Single Recto

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It's certainly possible that a faulty speaker cable could damage the tubes or even the amp, but you'd know more about it than just them going dull - that's the sign of normal wear, not failure from running with an open or shorted cable. From your settings it sounds like you're really cranking it - on most amps, halfway up on the masters is usually around the point the power tubes start to overdrive... which is good, if you want that, but it does speed up the wear a lot.

Personally I would avoid Monster cables... too big a failure rate in my experience. A lifetime warranty means nothing if a bad cable fries your amp. I would get a competent tech to make you some from 2-core power cable and Neutrik plugs - cheaper and tougher than anything else worth using. You don't need fancy cable and gold plugs for a guitar speaker connection, you need reliability... period. Power cable is designed to resist damage, will handle more than enough current, and Neutriks are the strongest plugs.


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PostPosted: Tue Aug 10, 2010 11:31 pm 
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Mark IV

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Amen! Don't buy for the name, buy for the build...period.

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PostPosted: Wed Aug 11, 2010 10:11 am 
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Mark IV

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94Tremoverb wrote:
From your settings it sounds like you're really cranking it - on most amps, halfway up on the masters is usually around the point the power tubes start to overdrive... which is good, if you want that, but it does speed up the wear a lot.


I have noticed that 3-5 out of 10 on the master for most amps, irrespective of brand/model, is where the "sweetspot" is. I only crank that loud once per week and the power tubes are most likely less than 6 months old.

I will check the bias with the weber bias rite soon to make sure it's in proper range.

This amp has a stereo power section (2x60watts = 120watts max). Never had an issue with it which is why it's my only tube amp right now (and the fact that it takes EL34's and is very versatile). thx.

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PostPosted: Wed Aug 11, 2010 10:27 am 
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Mark IV

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Looks like petrucci runs the masters and output around 4/10 (e.g. 11:00 - 11:30):

http://www.johnpetrucci.com/gear.htm

That's interesting b/c these guys are always mic'd...

Does he run EL34 or 6L6 or both???

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PostPosted: Thu Aug 12, 2010 12:18 pm 
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Mark IV

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I just talked to a guy at Rivera and they said they don't use JJ's anymore (they use Ruby tubes). He recommended =C= svetlana as well. I need to try those soon...

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PostPosted: Thu Aug 12, 2010 10:19 pm 
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Mark IV
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almost all of the speaker cables I use are made from old power cables from worn out appliances - I solder 1/4" plugs on them and go - some are nearly 30 years old and still going strong. you should inspect your cables occasionally ( like tire pressure, oil level, radiator water ) to make sure there are no broken connections as a tube amp should not be run without a load for any period of time

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PostPosted: Fri Aug 13, 2010 11:56 pm 
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thunda1216 wrote:
almost all of the speaker cables I use are made from old power cables from worn out appliances - I solder 1/4" plugs on them and go - some are nearly 30 years old and still going strong. you should inspect your cables occasionally ( like tire pressure, oil level, radiator water ) to make sure there are no broken connections as a tube amp should not be run without a load for any period of time
+1. 16 or 18 gauge stranded wire.

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PostPosted: Sat Aug 14, 2010 4:00 am 
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Single Recto

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Mine are all made from old power cable too. It's big enough, tough enough... and free.

But careful, or we'll open up that whole can of worms about 'conditioning' and cable 'directionality'... :-)


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PostPosted: Wed Aug 18, 2010 11:20 pm 
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Mark IV

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apparently the root cause was a bad preamp tube in V2 (not microphonic). after i replaced that one, the pinched harmonics are back. need to test again tomorrow but perhaps it wasn't the power tubes getting worn out (yet).

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