2. amps-preamps
  3. 176211-171531

5AR4 rectifier tube question

I am sort of shopping for one or more 5AR4s for a Cary SLP05 power supply because I’d like to have at least one spare and because I’d maybe like to roll two or three ad see if I can hear an improvement or vice versa. I make no claims of knowing much about the vacuum tube game; occasionally I get lucky & stumble on something that really works for me. As far as the 5AR4, I did a hit at Uncle Kevin’s site, and there were some that looked interesting (I am thinking of one in particular, it had a Japanese sounding name that started with a ’M’) but when I click on it, all I get is a picture of Uncle Kevin’s screaming face telling me "not to buy tubes" (later, when I finally took time to read, apparently his tube tester is down).

So I started doing hits on Ebay, and oh my gosh! I was inundated with choices and the variation in prices! Which do I stay away from and which should I be interested in? Would a 5AR4 from Bugera also be suitable for what I’d want to use it for? Could a rectifier tube provide a big sonic upgrade if I spent enough money on it? Can I make a sonic upgrade from what I believe (I haven’t opened up the power supply yet) is the stock EH 5AR4 without breaking the bank? I would be totally good with the $50.00 range and picking up 2 or 3 different ones to play with if those with experience thought I could improve the power supply in that range. If I had to I guess I could go more (the $100.00 range) but I probably wouldn’t be buying too many of them, and I was kind of HOPING not to go much over that.

Anyway, thanks in advance for the input; I always consider it part of my education.

immatthewj
immatthewj OP
1,874 posts
 

Cary could have made a removable access panel for the tube in the side of that power supply.

But, @rodman99999   I should have read your reply more carefully before I took it apart again and then put it back together.  I seem to believe in measuring once & cutting twice.

However, if I counted correctly (& I did actually count twice) there appear to be ten total teeth in the top mica (so I am ASSUMING) that there are 5 per side).  The top mica is a shiny silver like color.  The bottom (mica?) is clear and has two semi circular notches in it.  As does the top shiny mica, 2 notches with the teeth in between.

Does ten sound right?  I was bitching about Cary not putting an access panel in it, but it's really not that hard to get down and remove the bottom, so I can easily look at it again.  I've got the rectifier tube warming up right now, but I haven't lit all the other tubes yet.

 

rodman99999
6,125 posts
 

    Some have four, some seven, but: forget the notches.

                                Not important!

                               How's it sound?

    

rodman99999
6,125 posts
 

     Here's something you may find interesting.

     There are some Mullards compared, for plate structure, etc and the last two both have the 5 tooth, top mica.

      Just a way to close in on the valve's year, but: not nearly as important as the condition, strength and sound.

https://www.google.com/search?q=identifying+mullard+5ar4%2Fgz34&oq=identifying+mullard+5ar4%2Fgz34&aqs=chrome..69i57j33i160.14529j1j15&sourceid=chrome&ie=UTF-8#kpvalbx=_5wJeYqXzL7CO9PwPpqq18AQ15

testrun
231 posts
 

I went through the same exercise with a Modwright Pre-Amp w/ outboard power supply.  After listening to a number of NOS options I ended up with a metal base.  It was expensive but had the most positive impact to SQ of any tweak i’ve done.   I think it was a ‘56 or ‘57.   

immatthewj OP
1,874 posts
 

@rodman99999 thanks! I did a quick skim of the URL you posted & I quickly caught this from one of the people who answered on one of the forums:

The Mullard GZ34 has a hole in the guidepin and the upper micas have 5 teeth per side. On a new NOS Mullard the flashing extends down BEYOND the level of the mica.

so I am not sure what "the flashing" is referring to, but I am petty sure I must have 5 teeth per side. . . .

Some have four, some seven, but: forget the notches.

Not important!

How’s it sound?

Well, it sounded good tonight . . . but here is the thing--it was not sounding bad before, and I frequently confess to not possessing The Golden Ear (& I don’t intend any sarcasm whatsoever with that term). I seem to hear incremental changes when they get worse more than I do when they get better. When things get incrementally better, I seem to get more comfortable & relaxed . . . but the thing on that is: it takes a while for me to fully realize & appreciate that feeling. I am absolutely horrible at doing A/Bs (unless what I am comparing is just radically different), & therefore I hate doing A/Bs. It would be hard to A/B rectifier tubes in this pre, as it would require getting it down & then pulling the bottom cover off.

But: I did like the way everything felt tonight.

 

 

 

 

 

 

 

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