12AX7 Mullard/Philips/Amperex NOS

[5150mod]

Hi all,

Just wondering what or if there is a difference in tone between these 3 makers of what appears to be the same tube construction?All from the 60's, same short ladder plate.

All I can find is that the codes are different ie,B =Blackburn UK Mullard,Delta=Heerlen Holland Phillips,etc.And are of the I65 construction.

But these tubes look identical in everyway.

So is there really a difference?

[Pedro Vecino]

To compare preamp tubes, should have equal transconductance. This last often establishes differences that wrongly are attributed to model.
At the same transconductance, short plates Mullard has a more lively reponse, with great bite and articulation. Very smooth and fluid.
Heerlen short plates is very similar but slightly less articulate in overdrive. In clean sounds have a more rounded tone and slightly more lows are present.
It is difficult to explain but if you compare both, you'll find these nuances.

[5150mod]

Well I purchased some more tubes of this same ,mullard,construction.A couple of 'r' code which are Canadian and some Bel which are Indian.So when they come in I will do a comparison of the 4 different makers of the Mullard/Philips short plate I65 12AX7.

So does anyone Know of any other makers of this tube?

[Rhodesplyr]

There's a Matsushita Japanese version of the Mullard ECC83; I've got a pair of them. I don't know for sure, but I've heard that production experts from Mullard helped them set up the manufacturing process. Some sort of licensing arrangement to meet demand for a popular tube? Who knows.

I don't know if I can give you wine-taster's descriptive adjectives for them, but my impression is that most people find them pretty close to the British version, if not quite as long-lasting.

[Alex R]

I don't know if I can give you wine-taster's descriptive adjectives for them

Oh I can. South side of the production line, obviously. The anodes glint a complex autumnal grey through the glass. Let's try the tone... mmm... I'm getting two-stroke exhaust notes, decaying into distant gunfire with a hint of mosquito. Very close to the Mullard except it doesn't bark like a dog.

Peace and love to all...

[Steve Conner]

mmm... I'm getting two-stroke exhaust notes, decaying into distant gunfire with a hint of mosquito. Very close to the Mullard except it doesn't bark like a dog.

Excellent review sir I have a pair of the Matsushita "6CA7"s, and the innards look identical to the old Mullard Xf1 single getter EL34s. I also heard the story about the Matsushita/Mullard link, I got the idea that Matsushita were given some of the old Mullard tooling.

I don't have any authentic single getter EL34s to compare them with- I'd have sold them if I had- but they bias up and sound very similar to the Mullard dual getter tubes. Fruity, complex, crows on a misty morning with a freshly oiled chainsaw aftertaste, whatever.

[dai h.]

Philips owned part of Matsushita(now Panasonic) until pretty recently. IIRC Philips offered technical know how while Matsushita management expertise. A lot of stuff from way back looks very similar, from tubes to transistors(early Germaniums had the same nomenclature--"OC71" etc.), capacitors.