Tubes

tonyb

Looking for replacement tubes for the Joule la-100. Give me a yell if anyone has these.

2-RCA or GE or Sylvania 5751
2-same brands in 6350
2-RCA or Raytheon 6EM7
2 OA2....RCA -CBS or ?

NOS preferred, I'd like to find some 5751's from Sylvania Black plate triple mica D getters with the yellow lettering but I know that's going to be the hard one. Is using a 12ax7 comparable ?

Can't find much info on other tubes people have used in this pre.

tonyb

Man, I'm getting slow. I just realized Brent Jessee is located 2 towns over from me. WTF....I can just drive over and pick his brain.

pitdogg2

tonyb wrote: »

Man, I'm getting slow. I just realized Brent Jessee is located 2 towns over from me. WTF....I can just drive over and pick his brain.

Great guy helped me

treitz3

http://www.whatsbestforum.com/showthread.php?5438-Tube-Supplier-and-cross-reference-thread

tonyb

I just ordered everything I needed from Brent, pick it up tomorrow, easy peasy even if it's a few bucks more. That way, if something goes wrong I can run right there.

heiney9

Curious as to what you ended up with since the website states he's out of stock on the Sylvania 5751 3m/bp

WagnerRC

I was going to look this weekend. Hey Tom. Thanks for that link. I appreciate that.

WagnerRC

Does Brent sell the Popes? just curious

heiney9

Which Pope's? Pope's are rebranded Philips tubes, so you would need to be more specific. Just like ADZAM and Ediswan, but all 3 can also be Brimar tubes in some rare instances.

WagnerRC

Thank you. I need to do more research.

F1nut

Tony, did you get the OA2's?

Do not use a 12AX7 in place of the 5751.

tonyb

Brock,
He had 5751 3m/black plates in NOS RCA's...not cheap but not too bad either. The 6350's he also had in RCA.

Jess,
Yep, OA2's are pretty cheap anyway no matter the brand. Same with the 6EM7's

My thought is to just do a fresh re-tube on the whole thing. I can hear some tubes are at the end of their life cycle anyway. It's funny in a way, you hear a certain sound you haven't heard in decades and you immediately know what it is.

Jess, is there a reason one can't substitute the 12ax7's ? Does it have to do with the biasing of the tube to the circuit ? I know Judd was very particular in the tubes he used and biased his pre's to accommodate specific tubes. That's why I'm not straying too far from his recommended tubes he suggested. Was just curious on the 12AX7's as they seem to be the comparable tube and more available in NOS.

mhardy6647

12AX7 has a higher amplification factor than a 5751. Other than that, they're essentially interchangeable (generically speaking) -- no idea about the equipment in question, though. The "exact" industrial version of the 12AX7 is/was the 7025 (FWIW).

In terms of the 12AX7 vs. 5751 -- They both have parallel 6.3 V (or 12.6V in series) filaments, and I don't think the filament current is different -- RCA RC-19 sez 0.15 A parallel, 0.3 A series for the 12AX7; 5751 is 0.175/0.35 A, respectively (i.e., draws a little more filament current than the 12AX7). I looked the latter up at http://www.tubebooks.org/tubedata/HB-3/Receiving-Type_Industrial_Tubes/5751.PDF

You have a tube manual, yes? A good collection thereof will cut through a lot of the noise
Plenty of 'em at http://www.tubebooks.org/tube_data.htm Collect 'em all

heiney9

5751 vs. 12AX7 probably a gain issue, since the 5751's have lower gain. 5751's are typically built for less noise and better triode matching, plates are shorter, most have a 3rd mica and extra support = less microphony and more rugged. IIRC, they are slightly more linear as well. All this is in general of course as there are some stellar Euro and American 12AX7's.

Joey_V

I'm looking for popes 6sn7.

mhardy6647

"popes"?

A brand or a flavor of 6SN7?

Joey_V

mhardy6647 wrote: »

"popes"?

A brand or a flavor of 6SN7?

As far as I know it's a brand and a specific type, hard to find. Only have 4 but need total of 6.

heiney9

Joey_V wrote: »

I'm looking for popes 6sn7.

Most (if not all) Pope 6SN7's are made in Holland, a Philips tube. So conversely look for a Holland made tube regardless of the name stamped on the tube. Holland made 6SN7's are a bit rare and not easily found as they were never plentiful.

H9

tonyb

Ha...you guys want to hear a good one ? A good bonehead move by me. So after reading up, and even in the owners manual, I get all the tubes I need before taking it out of service so I can just pop the top, replace the tubes and stick it right back in to break in.

After popping the top though, I find that it doesn't even take 6350's. Just the 5751's, 6EM7's and OA2's. I should have popped the top before I ordered the tubes, and I should have remembered when I installed them after I first got it. It's just a pain to remove and all that jazz that goes along with that like cabling just to see whats inside.

The serial # on this pre is 076, some of Judd's earliest achievements. He must have added the 6350's into the circuit with the MK2 version and later. What a maroon I am. lol

For some reason too, I've read that these earlier serial # pre's are sought after I guess. Look before you leap as they say huh.

F1nut

Tony, try the RCA 5751, but find that Sylvania. The RCA 6350 is the one to have. Yes, OA2's are cheap. The reason I asked is I have some I could have sent you. Check their pink/purple glow.

As noted, the gain is too high on the 12AX7.

tonyb

Jess,
I let them warm up for 2 hours before sending a signal....this 20 year old pre amp sounds better than it has a right too. Better than many modern ones I've heard. Consider my sack, blown way back. lol I mean dang it, best sound I've ever had in my home.

I have the RCA 5751's triple mica D getters in there now and they sound pretty frickin' good....and that's without break in. I do want to find the Sylvania's, but that's going to take some hunting.

tonyb

I know the other iterations of this pre amp is different than mine, but after close inspection of the manual, the 2 5751's it uses are of different brands and they are suppose to be that way. RCA's and the Sylvania, one for the mu follower and one for the gain stage. I guess Judd biased the circuit to accept those specific tubes in those positions for best sound. Not that you can't use another.

By the way, what's the big difference between a square getter and a D getter ? Besides the obvious, is there supposedly a sound difference ?

heiney9

You are really limiting yourself if you use a single rca and a single sylvania. There is no way to "specifically" bias a tube circuit for a "brand" of tube in this case. A 5751 is a 5751 electrically. The circuit can't tell and doesn't care what brand it is. Now the circuit designer could personally prefer those tubes himself. And can make a recommendation to use those to get the singular tone he was trying to achieve.

I have already given you my in depth opinion on the Sylvania tubes, yet you still are limiting your search to one specific label color. When in fact you should be looking at dates and construction. Label color of the same date and construction have ZERO differences, they are the same tube.

Usually square and D shaped getters indicate the age of the tube as those were more prevalent with tubes in the 50's. Not everytime, but many more times than not.

Some people when describing tubes use the terms Horseshoe, D shaped and Square getter interchangeably. In my experience with RCA and Sylvania tubes there is no audible difference (between D and Square) if they are the same construction and within the same few years of production.

Some Euro tubes that offered D, D w/foil and small and large halo have some minor sound differences, not nothing that I would consider earth shattering and most would find them the same.

Do some rolling in the 5751 position as there are better tubes than the RCA. The 50's Sylvania 3m black plate and gray plate are excellent choices (but have different sound characteristics) as is the Tung Sol and Raytheon and 50's GE. There is nothing wrong with using the same tube for both 5751 positions. It sound very much like the EE Mini Max pre in that 1 position was gain and the other follower. The combinations were limitless. In this case there aren't that many 5751's and only the handful mentioned are worthy.

That's all I'm going to say because you are stubborn and seem to want to hold out for a "yellow" label Sylvania 5751. . But what do I know, I'm just a tube hack........

Peace out

H9

heiney9

All that said, label color can be ONE of the indicators you're on the right track for the tube you are seeking. But that doesn't mean the same tube won't have another color or designation. I have GB, USAF, USN, JHS labeled Sylvania 5751's.............guess what? They are all the same tube distributed for different uses. Army, Navy, Civilian.

H9

MrBuhl

Brock "the tube hack" LOL, just couldn't resist the second post after peace-ing out could you!

That said, I love reading your posts on tubes of any kind, I wish I had a hundredth of that knowledge!

heiney9

It was meant to be tongue in cheek. I just like sharing and discussing my tube experiences. I've taken it quite seriously for some time. I don't claim to know everything. But I do read a lot and have a fair amount of experience with a limited array of tubes.

I just offer advice, we each have a different set of circumstances and expectations so I just put it out there in hopes it can save some body some aggravation or a bad experience. Lots and lots of misinformation and just plain ignorance out there. Just trying to help cut through some of that is all.

H9

MrBuhl

^^ I totally get that - I loved both posts! Wasn't saying anything otherwise. (and you've helped me many times already - it's appreciated!) ^^

tonyb

LOL, I may be stubborn Brock, but I still want to see if there is a sound difference. From what I gather so far, supposedly the tube I'm after with yellow lettering was designed at the time as an audio tube, made to be an audio tube, not a computer or military tube, or other IBM applications.

Has to be a reason why Judd preferred one brand in a given location over the other. Right now I have both RCA's in both positions and it sounds pretty frickin' good. Dynamics are as good as any solid state piece I've heard if not better. Female voices really shine on this tube.

My search for that specific tube is due to the fact I want to hear what Judd heard. I may or may not like it, who knows, but curiosity gets the best of me at times.

george daniel

I have a Sylvania 5751 in the front position and an RCA 5751 in the rear position in mine,, I have rolled others but this combination seems to sound better to my old ears.Just my .02

heiney9

Good luck Tony, and enjoy. Nothing wrong with hearing how the designer intended.

Never have I heard such a story about a tube, especially in the 50's. Sounds like lore to me, but there is a certain amount of fun in the hunting and the stories from 50-60 years ago. Lot's of bs created and perpetuated in 66 years.

For one thing if such a thing existed, counterfeiters and fakes certainly would be numerous and steady in supply.

But it's your journey and who am I to say what path to pursue and follow.

H9

P.s. I'm also of the opinion if you have tube gear and are unwilling to roll tubes, you're missing out.

F1nut

It's a well known fact that the 5751 Sylvania 3 mica black plate from the late '50's is THE tube in the Joule.