Author Topic: No love for the 6550?  (Read 1318 times)

Offline rollo

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Re: No love for the 6550?
« Reply #15 on: March 16, 2018, 10:59:24 AM »
  Not to my Knowledge. Should be a direct replacement. Not cheap at $300/pr NOS Reflectors.


charles
you definitely cannot use 6h30's in a circuit designed w/6922's.  there's much info on line about folks asking that very question.

doug s.


  I stand corrected I guess. My preamp had zero issues. [ Gary Dodd] Best to verify first.


charles
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Offline doug s.

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Re: No love for the 6550?
« Reply #16 on: March 16, 2018, 12:16:33 PM »
  Not to my Knowledge. Should be a direct replacement. Not cheap at $300/pr NOS Reflectors.


charles
you definitely cannot use 6h30's in a circuit designed w/6922's.  there's much info on line about folks asking that very question.

doug s.


  I stand corrected I guess. My preamp had zero issues. [ Gary Dodd] Best to verify first.


charles

this (below) is typical of info regarding these tubes.  (the only reason i know about this is cuz my pre uses 6922's, and a long time ago, i was curious about the 6h30's due to all the hype about 'em.  but, since i just recently got back my melos ma333r from mark porzilli w/all his latest updates - including a special tube mod - i'm not too concerned about the 6h30's any more.):

"...the first thing you should check is the filament
power supply. It should be able to deliver the current the 6H30 draws, a
normal 6922 draws 300 mA compared to the 825 mA of the 6H30. So this is most
likely a problem. Also, when used properly, the 6H30 draws about double the
plate current for proper operation, so make sure the power supply can handle
this or, sadly, it is a no-go situation. But, if the power supply can handle
the doubled load, the gain will still be half of that of the 6922. If those
problems aren't problems for you, then you can carry out the mod...."


doug s.

Offline tmazz

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Re: No love for the 6550?
« Reply #17 on: March 16, 2018, 12:49:01 PM »
Thanks Doug. I kind of figured that part to the modifications Dave did to his Cary were to allow the substitution of the 6H30, but I thought I would ask.

Sounds like it would largely be a function of how much extra umph you have in your power supply. I sent off an email to ARC tech support earlier to today, posing the question to them. I'll ne interested to hear what they have to  say, but after reading your last post I don't hold out much hope.
« Last Edit: March 16, 2018, 12:52:31 PM by tmazz »
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Offline doug s.

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« Reply #18 on: March 16, 2018, 02:47:14 PM »
Thanks Doug. I kind of figured that part to the modifications Dave did to his Cary were to allow the substitution of the 6H30, but I thought I would ask.

Sounds like it would largely be a function of how much extra umph you have in your power supply. I sent off an email to ARC tech support earlier to today, posing the question to them. I'll ne interested to hear what they have to  say, but after reading your last post I don't hold out much hope.
no problem.  but, you might want to contact mark porzilli regarding his tube mod.  (he included modding my four 6922 tubes in his upgrade to me.  i have yet to hear it, as i have only recently set up my main system, and only the source components; which feed my modest kitchen rig, thru the tape outs.  the melos doesn't even need to be turned on for that.  main rig speakers and amps still need to be set up.  long story about my main system being down so long, but it's getting closer!   :D)

anyway, as i have only ever heard one pre that i think "might" be better than the ma333r, (to my ears, of course!), and this was before its latest updates and repairs, (that pre is the ~$20k [circa 2010] purity audio silver statement), i do expect to hear nice things when i finally get my system up.  and, no doubt the tube mod will be a contributor.

so, according to mark:
"Melos has an upgrade we're going to make available once the website is up that attaches magnets in strategic areas of the tube to accelerate its amplification, lowers its noise and distortion. Magnetic acceleration was used on huge pictures tubes long ago. The technique literally makes the tubes outperform their own original specs as part for the task of electron acceleration is now done with magnetism such that the efforts in the tube internally are lessened and so distortion drops. It also pulls stray electrons away from the electrodes so noise drops and focus in the imaging improves. This will probably be marketed under the name NeoTubes with respect to the tiny, powerful Neodymium magnets used for acceleration. The cost is $85/tube and we're gathering feedback for testimonials now before we present them to the reviewing community....

...[the] magnetic acceleration... ...focus[es] the electron beam to the tube's plates and... ...draw[s ] away stray electrons from the signal path which makes for a quieter, blacker presentation. The acceleration basically does what adding a premium tube does but squared. Premium tubes such as Telefunken et al do a better job of directing the beam by using metal shields and focusing grids. But it's a mere fraction of what can be done with magnetism so they will outperform almost any tube type once treated."


doug s.

Offline tmazz

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Re: No love for the 6550?
« Reply #19 on: March 16, 2018, 04:17:50 PM »
Not really interested in doing any mods to the SP-9 right now. I just thought that if they were plug in compatible it might be fun to grab a pair of 6H30s and swap them in for the 6dj8s and see how it sounded. Current production 6H30s would only run me about $60 for a pair and if I didn't like them I could always swap them back.

Not looking to get into a big project,just a little one afternoon nervosa fix.

But if I can't swap them without modding the amp it will involve  much more effort than I was looking to put into this.
Remember, it's all about the music........

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Quicksilver Mid Monos
ARC SP-9
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Offline doug s.

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Re: No love for the 6550?
« Reply #20 on: March 16, 2018, 04:25:59 PM »
Not really interested in doing any mods to the SP-9 right now. I just thought that if they were plug in compatible it might be fun to grab a pair of 6H30s and swap them in for the 6dj8s and see how it sounded. Current production 6H30s would only run me about $60 for a pair and if I didn't like them I could always swap them back.

Not looking to get into a big project,just a little one afternoon nervosa fix.

But if I can't swap them without modding the amp it will involve  much more effort than I was looking to put into this.
the above i mentioned doesn't mod your preamp, it mods your tubes.  but yes, it's a bit more $$$, at $85/tube.  plus, you have to provide a tube.  but mebbe mr porzilli would cut you a break, as he still doesn't have his melos website up yet...

doug s.

Offline tmazz

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Re: No love for the 6550?
« Reply #21 on: March 16, 2018, 06:58:41 PM »
Oh wow, I thought that the preamp was modded to so that you could used those special tubes. But if he could mod some 6922s for me that might be interesting. $85 is not cheap, but I only need two tubes and I have plenty of spares on the self, so the grand total would not be that much.

Something to think about......  :-k
Remember, it's all about the music........

Nola Boxers
Sunfire True SW Super Jr (2)
Quicksilver Mid Monos
ARC SP-9
VPI HW-19 Mk IV/SDS/SME IV/Sumiko Blue Pt. Special
EE Minmax DAC/Bluesound Node/Denon 2910
TWL Power Cords/MIT Cables