Tube rolling 12au7 and 12ax7

[MBDK72]

Hello. Has anyone here experimented with different makes of pre amp valves in their valve integrated amplifiers? I currently use Tung sol for 12ax7 and Electro Harmonix for 12au7. I use JJ KT88 for power valves. What are your experiences for a balanced sound?

 

[Jazid]

Many have experimented! In my experience there are no hard and fast rules except these:

1. Knackered valves sound bad. This applies to the poshest as well as the most humble of them
2. Dont change valve types from the design eg. ECC82 for ECC83.

But yes, rolling toobs is fun, also frighteningly addictive. I'm writing this on behalf of a friend of course

 

[audio_PHIL_e]

2. Dont change valve types from the design eg. ECC82 for ECC83.

yes. same pinout but the voltages applicable to the anode and grid are different

 

[pmcuk]

These are about the most common valves for push pull amps. You will find endless comparisons on Audio Asylum, DIY Audio and Head-Fi. Just do some searching. If you're going to be geeky about these valves you'll find a lot more there than from WAM users, though we have some very good contributors here of course.

 

[rabski]

Most of us who are valve-heads have been through the 9-pin phase of experimenting and I suspect have reached similar conclusions. The designs are inherently decent but limited in some respects. Basically, there are small but significant differences, however, the hype and resulting prices for some variants are simply not warranted.

IME, there is nothing to beat NOS valves, but look for the less sought after types and you can do very nicely without blowing the budget. RCA, General Electric and some of the less obvious Holland-made types are worth a look.

It is always, always circuit dependent, but in general, for 12AU7 you'd struggle to do better than Mullard CV4003 and for 12AX7, Siemens or Telefunken. Just don't get pulled into the madness of paying £1000 for any 12xx7 variety. They aren't worth a tenth of that IMHO.

 

[pmcuk]

Just don't get pulled into the madness of paying £1000 for any 12xx7 variety. They aren't worth a tenth of that IMHO.

None of the 12xx7 varieties are as good as many, many better and cheaper valves. One obvious example is 6SN7 which will eat any of the 12xx7 for breakfast, but there are several more even better than 6SN7.

So it starts from the choice of amp/preamp you make. If you already have 12xx7 valves in your equipment it's a case of "err, well, if I were goin' to London I wouldn't start from 'ere..."

The 12xx7 are not "bad" valves as such, but as Rabski says don't throw money at them. Instead, consider what valve amps are about with better sounding front ends, and consider putting the money there.

 

[MBDK72]

None of the 12xx7 varieties are as good as many, many better and cheaper valves. One obvious example is 6SN7 which will eat any of the 12xx7 for breakfast, but there are several more even better than 6SN7.

So it starts from the choice of amp/preamp you make. If you already have 12xx7 valves in your equipment it's a case of "err, well, if I were goin' to London I wouldn't start from 'ere..."

The 12xx7 are not "bad" valves as such, but as Rabski says don't throw money at them. Instead, consider what valve amps are about with better sounding front ends, and consider putting the money there.

Are there any modern valves which can get close to NOS and not silly money? I’m thinking Sylvania, Brimar or Langrex.

 

[Jazid]

I use old stuff because I have "some" lying around.
JJ E83CC and ECC82 are well regarded on the forums.

 

[pmcuk]

Are there any modern valves which can get close to NOS and not silly money? I’m thinking Sylvania, Brimar or Langrex.

You're partly asking the wrong question. Because it's the actual internal structure that differentiates one type from another within the same family. Yes, it's partly the make like Sylvania or Brimar but that's very misleading because the very same valves can show up under many, many different labels. Langrex own makes will be rebranded - they don't make valves. Valves were made on several production lines in different factories, but once out of the door they could and did appear as anything e.g. Hewlett Packard, Philco or whatever.

This was made clear to me with the 28 6SN7 I once did a shootout with. The best sound to me were the angled anodes, whatever the label was. It was all in the construction. When you get geeky you'll start having conversations about box anodes, O getters and halo getters. But you really don't want to be spending valuable parts of your life on that particular cul-de-sac.

 

[enrae8]

But you really don't want to be spending valuable parts of your life on that particular cul-de-sac.

So true about much on the music and Hi Fi estate

 

[ChemMan]

I use old stuff because I have "some" lying around.
JJ E83CC and ECC82 are well regarded on the forums.

I use these in the Gold Pin version and I also have some Genalex Gold Lion. When I had the old Hybrid amp I spent €100 on 2 x NOS Tesla ECC 83. If anything they sounded a bit flatter than the JJ.

I like the idea of finding some NOS 12AU7 to try on my amp, but:

Basically, there are small but significant differences

The Gold Lion 12 AU7 sound a bit softer to me and so I prefer the JJ.

 

[Tarzan]

Are there any modern valves which can get close to NOS and not silly money? I’m thinking Sylvania, Brimar or Langrex.

The Gold Lions are quite nice, but my favourite is the JJ Electronic E83CC Frame grid- cheap in audio terms and sounds superb- at least it does in my system where l use them in my integrated amp and phono stage.

 

[Jules_S]

I don't understand the negative reactions that the 12xx7 tubes (and 9-pins in general) seem to generate - which seem to range from mildly-disguised contempt to outright raging hatred. What is it that's so bad about them that brings out this reaction? What do they do, or not do, that makes them apparently so unworthy?

I have 4 such tubes in my phono stage. According to the instructions it's 1 x 12AU7 / ECC82 and 1 x 12AT7 / ECC81 per channel, whereas on the board itself is printed 2 x 12AX7 per channel, so goodness knows which is right! At the moment I've got a Mullard-branded ECC83 and a Sovtek-branded 12AX7 per channel fitted , a bit of a bugger's muddle I suppose! (I know ECC83 / 12AX7 are just different names for the same thing, I was referring to the brand mixture) Worth trying to get a fully-matched set of 4 ECC83?

 

[rabski]

I don't understand the negative reactions that the 12xx7 tubes (and 9-pins in general) seem to generate - which seem to range from mildly-disguised contempt to outright raging hatred. What is it that's so bad about them that brings out this reaction? What do they do, or not do, that makes them apparently so unworthy?

They're fine. It's just that generally octal versions are better. The way valves work, roughly speaking a larger envelope has some advantages, as it allows larger internal structures.

 

[pmcuk]

I don't understand the negative reactions that the 12xx7 tubes (and 9-pins in general) seem to generate - which seem to range from mildly-disguised contempt to outright raging hatred. What is it that's so bad about them that brings out this reaction? What do they do, or not do, that makes them apparently so unworthy?

Quite simply, other valves sound better. As Rabski says the larger octal socket valves are a good example. What happened after WWII is that the USA needed large quantities of valves for things like computers and so miniaturised the format to save space. Audiophile quality wasn't needed for computers, televisions and radios, and so tended to decline in the miniaturisation process. Previous to WWII European valves used a variety of different bases and heater voltages (4V, 13V) all of which vanished as Europe and Russia jumped on the bandwagon and adopted 9 pin valves with 6.3/12.6V heaters. What remained of the larger valves were octal valves like 6L6 and EL34, mainly used for larger output valves but also input valves like 6SN7, and some odd bases like loctal which were locking and used for mobile devices.

Of the older and many consider better valves there survived a number of 4 pin directly heated valves like 2a3 and 300b. These survived because they sound marvellous, and are mostly used in smaller single ended amplifiers. What didn't survive, alas, are the small signal varieties like 26, 10Y, 01A, 112A etc. but there are still stocks of used ones available.

So in general and as an extreme over-simplification, the quality goes in rank order:
- 4 pin directly heated valves
- octal valves
- 9 pin valves

 

[Jazid]

I don't understand the negative reactions that the 12xx7 tubes (and 9-pins in general) seem to generate - which seem to range from mildly-disguised contempt to outright raging hatred. What is it that's so bad about them that brings out this reaction?

Personally I love them. A bit of a "counter-reformation" position but they have qualities sadly lacking in older valves, like efficiency, size, low microphonics, and availability.

They also make exciting things such as my oscilloscopes and curve tracer work

 

[Jules_S]

So far I'm hearing "other valves are better". But what I'm not hearing, is in what way better. Not wanting to start a fight here, just genuinely interested because apart from our @Jazid above, I'm still not feeling the love.

What is the magic that these others sprinkle that the 9-pins apparently don't? Does this larger internal structure result in a more evenly balanced tonal range? Better control in the bass regions? Better dynamic swing? Better resolution of low-level detail? Increased separation of instruments? Better-defined soundstaging?

This is the sort of info I'm interested to hear about, and I'm specifically talking about these small signal valves rather than the power output ones like the 2A3 / 300B / 211 / KTxx / ELxx. What commercially-available alternatives exist nowadays that are used outside the DIY community? And is it mainly down to availability / cost that the likes of the ECCxx have become ubiquitous?

(with apologies to the OP if I'm dragging this slightly OT but I thought it was broadly relevant to the original question)

 

[pmcuk]

The distortion figures at 1K will give you some idea. The first figure is the gain, followed by distortion - lower=better. You can see that the stars are octals like 6J5 and 6SN7 together with some directly heated triodes like VT-25 (10Y) and 6B4G (a 2a3 type). Some of the 9 pin valves do OK like 6N30 but not the common ones. The 12AU7 is higher and 6922 and ECC88 are particularly high on distortion. Red is lowest, then blue, then black.

 

[Jazid]

With all respect, Andy, without knowing the operating points and test rig this list doesn't mean much. Very different valves, very different behaviour to be expected, almost entirely dependent on operating conditions.

As another very great generalisation postwar valve designs tended towards greater gain and transconductance with decreasing size and heater power, for use in smaller spaces.

Without wishing to poke a hornest nest (sensitive souls may wish to take to a safe space) with a bit of local negative feedback the distortion of a medium to high gain valve can be made vanishingly low. In the 1950s/60s audio designers were comfortable employing feedback to improve circuit performance. Earlier low mu triodes, which can indeed operate in a more linear manner than later triodes need to be more linear, because they can't benefit so much from the use of feedback due to the loss of some of their already low gain.

Design compromises and circuit choices. Hey ho!

 

[JANDL100]

It's TAD for me.
2 word review - holographic clarity.
I luv em.
Yes, I've heard loads of others.
And yes I know they are just selected Chinese. But they are consistently excellent ime.
My jaw dropped at a bake off when someone subbed in a TAD 12ax7. Been a convert ever since.