5963 an option for 12AU7 in ST120?

Guess the title says it all ...

Found this on the web:

This tube makes a decent substitute for the 12AU7 as the characteristics are almost the same. The 5963 has a slightly lower plate voltage rating compared to regular 12AU7. The 5963 has a max plate voltage of 250V while 12AU7 has a max of 330V. This tube has a specially designed cathode which can withstand long periods of time in cut-off without hurting the tube.

Not sure if these would be a direct plug in on an ST120 or if there'd need to be any internal mods for them to work.

I expect I could just plug them in and see if they explode?   

Beauty!

(What took you so long?)   

Anybody have any first hand experience with these? Always looking for other options ...

Also, the Brimar 13D5.

sKiZo wrote:Beauty!

(What took you so long?)   

Anybody have any first hand experience with these? Always looking for other options ...

Be careful to get tubes tested for microphonics, a number of 5963s are excessively microphonic. But a good one is a FINE tube!

Good to know on the microphonics.

Long as we're adding tubes to the list, The Brimar 13D4 and 13D8 are apparently other variants of the 13D5 industrial tube ... I also see there's a premium version, the T6067, that's supposed to be on a par with the prized Mullard and Amperex offerings.

All of those tend to be pretty expensive and hard to find though. The 5963's seem to be bargain basement in comparison and get great reviews.

I recall that I had a 5963 that was microphonic, but others were very good.

If you'd like to try something really rare, look for a pair of 7730s. Good luck.

Went over to that auction site and picked these up ...



Pulls from broadcast equipment, so I'm keeping my fingers crossed on the microphonics thing. I imagine they're also matched date, coming out of the same rig. $35 shipped seems fair - they look new.

Got em in and fired em up ... real sweet! Got a nice strong midrange that really makes the vocals pop. Clear and crisp at the top too. Only complaint was the bottom was a bit fat - solution there was to swap the KT120's out for a quad of Psvane KT88's. That toned down the bottom and cleaned it up nicely. Not muddy - just strong.

Bit of fun here ... I was crankin' some Porcupine Tree to test it out, and all of a sudden started getting some horrible noise - Holy Crap! System shut down with a power blip. Good news is, it wasn't the amp ... it was just inch size hail and 80mph winds. Ah ... springtime in Michigan!

PS ... my non-latching GFCI adapter did it's job. Amp shut down and stayed shut down until I reset the adapter. The rest of the system blipped and restarted, but that's all solid state and doesn't have the short cycling issues you get with tubes.

Methinks I went a little overboard here, I bought a bunch of NOS "12AU7s" to try out here on some of Bob's recommendations that I have not yet tried out.

I got a quad of mid '55 GE 12AU7s black plates, a quad of 1970s Tungsrams E80CCs, a quad of GE 5814As, a quad of early '60s grey long plate 5963s, and a quad of late '50s 12AU7 clear tops. I'll report when I get a chance to run comparisons.....right now dialing in interconnects and rectifiers.

You must learn self control. Moderation in all things.

PS ... box one of two ...



Addictive, ain't it?   

sKiZo wrote:You must learn self control. Moderation in all things.

PS ... box one of two ...



Addictive, ain't it?   

oh no...thats way too organized!.........  

MontanaWay wrote:

sKiZo wrote:You must learn self control. Moderation in all things.

PS ... box one of two ...



Addictive, ain't it?   

oh no...thats way too organized!.........  

Is there are 12 step program for this?

VTHokie83 wrote:Methinks I went a little overboard here, I bought a bunch of NOS "12AU7s" to try out here on some of Bob's recommendations that I have not yet tried out.

I got a quad of mid '55 GE 12AU7s black plates, a quad of 1970s Tungsrams E80CCs, a quad of GE 5814As, a quad of early '60s grey long plate 5963s, and a quad of late '50s 12AU7 clear tops. I'll report when I get a chance to run comparisons.....right now dialing in interconnects and rectifiers.

That being said, anyone who can give any suggestions with the over zealous tube purchase I have, and any experience in a VTA ST-120 or Dynaco amp with these tubes?

Only ones in that list I have specifics on are the RCA clear tops. Those are a bit of a sleeper, performing WAY above their price point. Very nice range and a good ... er ... clear top ... on them, as in strong upper mids and highs. Big fan here.

Even better are the 1940's production foil getter versions. Got a nice matched triple of those that sound choice with the KT120's.

Does seem like a nice assortment, and you'll be surprised the difference they make. Do some swapping and go with what works best for you and your system. I would have never considered Westinghouse as a "quality" tube until I scored some in a grab bag special, and now they're some of my favorites. I also run a couple WH 5670's in my DAC, and they sound better to me than a Telefunken or Tesla at a fraction of the price.

Don't forget, you can mix brands and types too when you're auditioning tubes. The center driver is most important, but the channel drivers add flavor. Probably best you stay with matching tubes in the side channels, but playing with those can be handy if you have a problem room, with one side that's too bright or dark, sonically speaking.

sKiZo wrote:Only ones in that list I have specifics on are the RCA clear tops. Those are a bit of a sleeper, performing WAY above their price point. Very nice range and a good ... er ... clear top ... on them, as in strong upper mids and highs. Big fan here.

Even better are the 1940's production foil getter versions. Got a nice matched triple of those that sound choice with the KT120's.

Does seem like a nice assortment, and you'll be surprised the difference they make. Do some swapping and go with what works best for you and your system. I would have never considered Westinghouse as a "quality" tube until I scored some in a grab bag special, and now they're some of my favorites. I also run a couple WH 5670's in my DAC, and they sound better to me than a Telefunken or Tesla at a fraction of the price.

Don't forget, you can mix brands and types too when you're auditioning tubes. The center driver is most important, but the channel drivers add flavor. Probably best you stay with matching tubes in the side channels, but playing with those can be handy if you have a problem room, with one side that's too bright or dark, sonically speaking.

Skizo I appreciate the reply. I was going to start with the clear tops and the E80CCs and see how they work....I'm intrigued by those the most from what I've read. But I just couldn't stop buying when some of the others fell to my price point!

I'm not the best at "detailed analysis", but like many go by how they sound to me. I'm going to try them in "like" sets of 3 until I get a good foundation, and at some point will try mixing and matching the sides and the middle.

Wanna have some fun?



I figure with a potential two tube types per set (side and middle) times the number of tubes I have, also divided by two to compensate for the matched channel drivers, the grand total of possible combinations is around 410 ... gets a bit more complicated factoring in unique single drivers as all my tubes aren't in matched sets of three.

Or in other words ...  

sKiZo wrote:Wanna have some fun?



I figure with a potential two tube types per set (side and middle) times the number of tubes I have, also divided by two to compensate for the matched channel drivers, the grand total of possible combinations is around 410 ... gets a bit more complicated factoring in unique single drivers as all my tubes aren't in matched sets of three.

Or in other words ...  

sKiZo....even with my engineering degree and minor in mathematics, that is frightening.....ah what the hell, it'll be fun just the same

To the collected brain trust here, I have a question. My rectifier tube on my VTA ST-120 "wiggles" around quite a lot, to the point it will even touch against the transformer. The receptacle itself is mounted tight, but the pins that hold the tube are loose enough to give the tube that amount of play. Is that normal? If not should I replace the receptacle? Any opinions?

VTHokie83 wrote:To the collected brain trust here, I have a question. My rectifier tube on my VTA ST-120 "wiggles" around quite a lot, to the point it will even touch against the transformer. The receptacle itself is mounted tight, but the pins that hold the tube are loose enough to give the tube that amount of play. Is that normal? If not should I replace the receptacle? Any opinions?

I would first try to re-tension the socket pins.  It amounts to taking something like a small screw driver and with a little force making the pins sockets smaller in diameter.  Just Google "tighten tube socket" and you will see many examples.  Of course power off and bleed the caps prior to getting close to the tube sockets.

You didn't mention the rectifier you're using. I had wobble with my big bottles because the bases overlapped the socket mounting screws. Rather than take those out, bevel the holes, and change out to recessed screws, I added some felt pads for the tubes to sit on.



Just felt peel 'n stick pads you can get from the local hardware, cut in half so they're more or less hidden under the bases ...

And ya ... if you do a lot of rolling, it's possible the socket has loosened up. Wouldn't hurt to retension it - if nothing else, that will ensure good electrical contact, but ...

The pin connectors in the sockets provided with the kits DO float quite a bit, which I expect might be what you're experiencing. I suppose there's some way to tighten those up - some sort of flaring tool to push the bottom of the connection tight to the holes? Thing is, as long as you've got good electrical contact, and they don't move around if you're not pushing them, well ... don't do that.

PS ... I prefer a wooden toothpick to most anything else for shrinking the connectors if they're loose on the tube pins. Nice taper and minimal chance of going overboard and damaging things. And also, the connectors won't normally loosen up much if you keep the tube straight and apply even pressure to remove or seat it. Rocking it, or maybe trying to push it into the transformer for instance  (;-)  - that's what loosens them up. So, ya ... I'd think yours might need some attention.

Oh. Just a thought ... the rectifier would be the most prone to this rocking thing as it has fewer connections than the power tubes. All the extra solid wire connections tend to stabilize those better? Anyway, do the diode mod, and that gives you two less loose pins floating. Also a good idea to protect the amp.



Also, a slight twist of the solder tabs will help lock them in place. As you can see in the pic, I usually fold mine back just a bit - accomplishes the same thing.

Yep, SkiZo, toothpicks make great shims. You can use them for small repairs e.g., when a small hole in wood becomes slightly enlarged.

BTW: I'm still fixated on Kevin @ Dynakit Cinch(tm) sockets. The solder lugs never come loose. They're marvelous. Kevin buys them from a man in in Arkansas, who bought out Cinch's supply back in the '70s, when Cinch was discontinuing production. Here's the pic:

Mil-spec socket

I forgot this is at 5963 thread, and I do apologize for veering us off of topic.