Originally Posted by yrh0413
the thread starter's EF92 is Mullard driver tubes (6CQ6 MA - CV131), but those on my LD2+ have the designation 6CQ6 WB and 6CQ6 WM. Any difference?
When I received the LD2++ it came with Ediswan EF92 not Mullard. At that time I had also sourced some Mullard CV131 - 6CQ6 as a rolling option. The Mullard tubes do
sound different to the Ediswan. As "thread starter" I supose I should try and clarify the puzzles with some tube markings. From what I gather, the EF92 code was originally for Telefunken - Ediswan - Siemens but not Mullard, they
had their own code systems, but it's common for tubes to have codes printed on them which relate to alternate brands, such as finding EF92 on a Mullard CV131. So some tubes will have additional markings & codes to that of the actual maker, I suppose that if a replacment/equivalent
tube was seen to have the 'expected'
code from an alternate brand on it, then it may sell better.
To the question of the characters (MA, WB, WM) near to the Mullards '6CQ6' code on the CV's.. The characters usually are different, think of the characters as factory batch, group or lot numbers from manufacture. Sound isn't different.
Originally Posted by vcoheda
I don't know what all the coding on the tubes mean, but if a tube has the same brand (for example, Mullard) and number (CV131), I bet it sounds pretty much same, despite the presence of other coding.
Maybe someone else can chime in here.
From what ive worked out, the CV codes were introduced for the military/government. Phillips, JAN and Mullard made a lot of tubes for them but not many were labelled with their logos. Some tube packaging can also have codes that refer to other brands printed or written on them. This military symbol is that of three vertical lines that join at the top as so..... /l\ ....but please note that if a tube does have this symbol on it with other codes it does'nt necessarily mean its a 'Military Issue' tube but simply the makers way of saying its an equivelant.
Below is a list of makers code markings found on the actual tubes
not the boxes. Each tube is grouped with its 'equivelants'. I assume that as Mullard made both a CV131 and CV4015 that it's highly likely that companys such as Westinghouse or Marconi’s Wireless Telegraph Co. etc, could have produced both types also. There are Lots of other brands which are not included on the list as I can't verify the markings ( that's for a future post
)Driver Tube Codes - Lettering as found on Tube
Military /l\ (Mullard) ----- CV4015 6065
Mullard ----------------- CV4015 M8161
Westinghouse ----------- 6065
Military /l\ (Mullard) ----- CV131 6CQ6
Mullard ----------------- CV131 6CQ6
MWT ------------------- W77
Ediswan ---------------- EF92
Brimar ------------------ 9D6
Sylvania ---------------- CV4015Power Tube Codes - Lettering as found on Tube
- Only the first column of numbers is on the Tubes (in Russian) -
Svetlana ---------- 6C19П-B ----- (6S19P-V --- 6c19pi-B / 6c19ri-B)
Ulyanov ----------- 6C19П-B ----- (6S19P-V --- 6c19pi-B / 6c19ri-B)
Svetlana ---------- 6C19П ------- (6S19P --- 6c19pi / 6c19ri)
Ulyanov ----------- 6C19П ------- (6S19P --- 6c19pi / 6c19ri)
Beijing (China) ----- 6C19-J
The 6C19П is a small power triode used in some high-end amplifiers.
The Transcendent Sound T16 OTL ($3229 Tube Amp)
uses 16 of these!
The WooAudio 4 - Single-Ended Class-A ($1150 Tube Amp)
The REX VK-52SE ($10,000 Tube Amp)
uses 4 of them,
But most importantly the LD2++ has 2 aswell!
will take you to a simple webpage with a number of different tube boxes listed and pictured, another handy place for checking logos.