Re-Tubing My Dynacos / Questions

[fwphoto]

After too many months in the shop for a light refurbishing, I'm about to get my PAS-3 & ST-70 back.The guy at the shop almost threw the cheap 12AX7s that were in the PAS-3 at me when he opened it up! "Garbage," he shouted, "Get them out of my sight!" Anyway, I've decided to replace all the tubes so I don't have to mess with with it for awhile. (I don't expect to be a "tube roller.")

So I've got a bunch of questions! Feel free to chime in on one or all of them!

- Aside from biasing the tubes in the ST-70, is there any reason that the new tubes be in the amp & preamp when I pick them up? I just don't know if the shop has the tubes I'm interested in at a price I can afford.

- At my price point, I'm looking at mostly JJ Electronic tubes. Here's what I'm considering:

For the ST-70:

- 4 Matched E34Ls. These are the slightly higher output version of the E34.

- 2 6U8 tubes (possibly JAN Phillips?) instead of the seemingly unavailable at a reasonable cost 7199. I'll have my tech rewire the sockets for them.

- 1 5AR4/GZ34 tube rectifier.

For the PAS-3:

- 4 Matched, Balance, Selected for Low Noise & Microphonics, gold pinned ECC83Ss. I'd consider the "high performance" longer-plate ECC308S but I've read they have a tendency to suffer from increased microphonics. Thoughts? I'd also consider KT77s by JJ or Gold Lion but really don't know either the up or downside of them.

- 1 12X4 I've seen various manufacturers & they seem to be pretty cheap.

So, what do you think? Am I on the right track?

TIA,

Frank W.

[doctorcilantro]

Sounds great. What tubes did he almost throw at you? I'll send you a PM about the Genalex re-issues. If I can find some 6U8 that test okay you can have them.

DC

[DanO55]

Months! I'd find a new tech. for your Dynacos. Personally, anything but JJs. Reissued Mullards in my opinion. And get some tele's in that PAS-3.

[fwphoto]

Sounds great. What tubes did he almost throw at you? I'll send you a PM about the Genalex re-issues. If I can find some 6U8 that test okay you can have them.

The tubes were labelled International C & Servicemaster. I'll send you a PM about the Gold Lion KT77s & the 6U8s. I assume you thinks its a good idea to do the modification to use 6U8s intead of 7199s?

Frank W.

[fwphoto]

Months! I'd find a new tech. for your Dynacos. Personally, anything but JJs. Reissued Mullards in my opinion. And get some tele's in that PAS-3.

Yeah, I hear you. Thing is, there just aren't that many techs out there. This one was referred by a very good friend (& high-end audio guy) who had some Mk IIIs, I think, refurbed by the guy. The tech is kinda quirky, but I trust my friend's recommendation.

So, what's the issue with JJs? I haven't heard a lot of great things about the Mullard reissues, but I really don't have a great frame of reference. That's why I'm asking abound here. ;-)

I have read the gold pin JJ ECC83S is similar, at least in design, to the telefunkens. Again, I could be totally wrong.

I really just want a decent set of tubes that I can enjoy wth my Forte IIs for awhile. I can't afford NOS Telefunkens, though.

Frank W.

[thebes]

I do believe International was a rebrander and could be anything form Mullard to Check. It it's IEC they are Mullards.

[fwphoto]

I do believe International was a rebrander and could be anything form Mullard to Check. It it's IEC they are Mullards.

Nope, no IEC.

Any words of wisdom for me in my dilemna? Without being able to audition any of these tubes it seems like a crap shoot to me. I really don't think I want to get into the cost & uncertainty of NOS. I know its a compromise to go new, but if I research the better brands & get the best they, and their retailers, offer, how bad could it be?

Frank W.

[doctorcilantro]

KLIPSCH NEEDS TO MAKE THIS FORUM CHROME FRIENDLY!

Found it:

http://pax-comm.com/pa01019.htm

I have seen some nice etched date code Mitcham and Blackburn plant Mullards simply silk-screened with IEC.

[mark1101]

For current production 12AX7s I have tried ElectroHarmonix (EH), JJ, Tung Sol, and Sovtech. The Tung Sol had the highest gain, but I felt the best sounding, and what I keep buying over again is the EH gold pin 12AX7. Very balanced, and low noise. Not as detailed as a $190.00 NOS Telefunken, but only costs about $25.00. The non-gold pin versions are around $12.00 and are probably just as good.

[DanO55]

I have had a lot of failures with the JJs I have used. I found the reissued Mullards very close in sound to the Mullard XF2s. Ran eight of them in a stereo set up for over a year without a single problem. Yep, telefunkin branded 12ax7s aren't cheap. Look for a pair of relabled Fisher's. etc. If you are not running a turntable, a set in the line preamp side of the PAS is all you need. Something to ponder down the road perhaps.

[Audible Nectar]

Used Teles are worth the money and not too hard to find - just find a reputable seller with a return policy on the 'bay and problem solved. Good used quads can be found in the $125-200 ballpark. Often these can be found with Fisher or Dynaco labels and won't set you back TOO much - and will last a LONG time, especially if you find a good strong set that hasn't been run hard. A good used set will outlast pretty much ANY current production, and sound better, too.

[fwphoto]

Used Teles are worth the money and not too hard to find - just find a reputable seller with a return policy on the 'bay and problem solved. Good used quads can be found in the $125-200 ballpark. Often these can be found with Fisher or Dynaco labels and won't set you back TOO much - and will last a LONG time, especially if you find a good strong set that hasn't been run hard. A good used set will outlast pretty much ANY current production, and sound better, too.

While I'm certain all you say is true, I just want to get my system back together asap & listen to some music. I've been doing the hobby thing for awhile but right now I just don't have the energy to experiment.

Cost wise, I think I could stretch to your ball park. Yesterday I talked to the tech that's working on my gear & he says he has some NOS tubes I might be interested in (including some variety of Mullards for the PAS-3) so I will check them out.

I am looking for long-lasting tubes & figured that new tubes, in general, would last longer (or at leats as long). Are you saying that current stock, premium-grade, tested tubes won't last as long as vintage NOS tubes that can be found at near equal cost?

I would LOVE for my tech to be able to put me into some great NOS tubes at prices I want to pay. If not, I want to buy some decent sounding tubes that will get me back in the game. Eventually, as time & $s dictate, I'll probably get into a bit of tube rolling, You know, buy a quad of this or that, now and again. Until then, I'm willing to go with good current issue tubes.

Frank W.

[Audible Nectar]

In the realm of 12AX7s, there is NO TUBE - and I mean NO TUBE that lasts and lasts like the Telefunken 12AX7. Good strong light/moderate used Teles can and will outlast new current stuff. I have a Mcintosh MX-110 with the original Telefunken 12AX7s in there, a two owner unit (the original and me) that used it regularly. They test close to NOS.

In some of the applications I use Tele 12AX7s in, they get WORKED. For example, the driver slots in vintage Mac amps, where they get hit with 440VDC all day long. I ran a good 8-10,000 hrs on a single set of Tele 12AX7s at that aforementioned 440VDC, and had those tubes tested before and after on calibrated and voltage regulated test gear. These tubes were used to begin with, and lost some noticeable transconductance on test measurements, but still worked great in the amps and exhibit close gain characteristics. And these tubes were the most "hard ridden" of my good testing Tele 12AX7, the ones I figured I would "use up" since I got them for free doing some favors for a forum member. I only recently rolled them out of those slots, but still use them in the first preamp slot on my MC30 power amps because they only see 110VDC. They'll run another 10K hours in that slot, as they still test a good 35% above the mininum good on verifiable tests, and are still preamp quiet.

Philips (Mullard or Amperex) plant tubes also were good tubes as well as Seimens, and all would be considered amongst best possible options over anything in current production. These old tubes were made in the heyday of vacuum tube technology, when military and electronics companies were demanding the BEST that technology could deliver. They didn't last like Teles, though....5-10K hrs total depending on application would be a reasonable expectation.

Now you can get acceptable sonics from current production tubes, but I've yet to see a piece of gear where a bit of tube rolling into good vintage tubes wasn't a benefit....especially in key slots like preamps, or use of Mullard rectifiers where reliability is demanded on a tube rectified device. So I would say that it's quite OK to use current production tubes if that's what your budget will allow, but there are certainly benefits to using the vintage tubes if you decide to go that route.

[NOSValves]

Months! I'd find a new tech. for your Dynacos. Personally, anything but JJs. Reissued Mullards in my opinion. And get some tele's in that PAS-3.

Not to butt in but quality technicians will always be backlogged. If a technician is sitting around with nothing to do I would run as fast as I could to find another. At one time I was 7 or 8 months behind... I now work fevorishly and refuse to work on basket case type projects and keep myself about 4 to 6 weeks behind. Quality tube audio technicians are hard to come by. I never advertise and if I took in all work offered to me I'd again be 8 months behind.

[NOSValves]

I've probably tested 2 or 3 thousand used Telefunken 12AX7's and can count on my two hands how many of them were bad or weak. What is even more crazy is they almost always test identical....talk about quality control. Not sure what kind of magic dust those Germans put in the Telefunken ribbed and smoth plate12AX7's but those things just will not die... No other 12AX7 or any other tube I have experience has that kind of life span except the British Mullard CV Military series of tubes. Then when coupled with kind of vintage sounding gear (Soft) they also sound the best IMHO. To bad with more modern tube gear they seem to be a bit mechanical and bright.. No wonder just about all the best vintage gear manufacturers used this tube.

[Audible Nectar]

I'm not such a big fan of Tele 12AX7s in modern gear either (usually Philips/Amperex/Holland is preferred), but in vintage gear, like Mac, Fisher and Dynaco, they are an ideal fit. Teles are also critical in Mac amps like MC30s....that midrange they are famous for is due in large part because they were outfitted with Tele smoothplates. Those amps are just not the same with other 12AX7 tubes - even vintage ones.

[fwphoto]

I've probably tested 2 or 3 thousand used Telefunken 12AX7's and can count on my two hands how many of them were bad or weak. What is even more crazy is they almost always test identical....talk about quality control. Not sure what kind of magic dust those Germans put in the Telefunken ribbed and smoth plate12AX7's but those things just will not die... No other 12AX7 or any other tube I have experience has that kind of life span except the British Mullard CV Military series of tubes. Then when coupled with kind of vintage sounding gear (Soft) they also sound the best IMHO. To bad with more modern tube gear they seem to be a bit mechanical and bright.. No wonder just about all the best vintage gear manufacturers used this tube.

Well, heck, where can I get me some of them Telefunkens at a reasonable cost? I've recently seen some smooth plate ones on the web for $35 but have no idea if its a current ad.

Also, thanks for the comments about busy techs. I was pretty happy to find one fairly close to me, especially one that came from a personal recommendation. I'll be speaking with him early this week & I'll definitely ask if he has any Telefunkens for sale. I suspect he does, I just don't know what he'll be asking for them.

Take care,

Frank W.

[fwphoto]

So, another question. It looks like the concensus is NOS (or used) Telefunkens, Mullards, etc. I'm thinking this is most important for the quad of 12AX7s in the preamp & the quad of EL34s in the amp. Right?

How about the others? My tech did mention he had NOS 7199s that he said he'd prefer me to use (if the ones in there are not so good) rather than doing the simple mod to use 6U8s instead, so I'm good there. How about the tube rectifier, 5AR4/GZ34? Does this need to be something special? How about the 12x4? They seem to be pretty cheap wherever see them.

This is getting costly! ;-)

Frank W.

[DanO55]

The GZ34 is going to cost. You can use new but I guarantee ya, eventually you will get a Mullard. It will probably be the last rectifier you buy, They last forever.

[fwphoto]

The GZ34 is going to cost. You can use new but I guarantee ya, eventually you will get a Mullard. It will probably be the last rectifier you buy, They last forever.

Wow, they sure are expensive! I imagine there's a difference in sound, but I could buy at least 5 new tubes for what I've seen NOS (or used, tested as new) Mullard GZ34s going for.

I figure I'll hear the difference with 12AX7s & EL34s, but the others?

Frank W.