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What is the difference between a Mullard tube marked CV4004 and a Mullard tube marked ECC83. It seems strange the a company would mark the same tube with 2 different designations. Is one a tube and one a valve ie one for the American market and one for the home market (UK)?
Edits: 10/15/14Follow Ups:
I have been liking the 12ax7s French made with the double supported halo getter. It seems to be very neutral steps out of the way and lets the music play. cheers, Dak
CIFTE? Radiotechnique? Thomson?
Big J
"... only a very few individuals understand as yet that personal salvation is a contradiction in terms."
I bought a lot of CV-4004 box plates for 50 dollars each and they were driver grade but they sound ok.I have 100s of 12AX7s of all types and my favorites are the Telefunken smooth plates and the RCA black plates and the Amperex DD getter.The 10M Mullards are superb but they are out of reach as are the Telefunken ECC803s.
Vintage Mullards are ok when they work but they turn microphonic at the blink of an eye..The New Sensor 12AX7s along with the 12AX7LPS are getting much closer in the right circuits and now I basically mix old with new to get the best sound.I also like the Raytheon 5751 windmill getter a lot in driver applications.
"
The Mullard CV4004 besides being of driver grade are also excellent in phono sections. Provides a ultra low noise floor and an uncolored sonic signature.
This was verified with a group listening to various 12AX7 tubes with a highly modified Fisher 400 & 500 series receiver. Listened with JBL L300 speakers, a Garrard 401 with Jelco 750L tone arm, Grado cartridge & a custom 6922 based phono preamp that handily outperformed a Denon AU-340 SUT.
As odd as this reads, the only amp so far that can perform in the highly modified Fisher territory is an upgraded Marantz 8B.
So the RCA black plates are topping the list. Great being I am using them.
I contacted Jim and I'm ordering a backup set of 12AX7's. Tung-Sol
reissued ECC803S gold pins. I likee having a complete backup set of tubes to any amp I use and love.
charles
Excellent tubes you ordered.
"
CV4004 box plate are good sounding tubes. So are the Mullard 12AX7/ECC83 long plate. I am not a fan of the Mullard 12AX7 short plate.
Mullard CV4004 were originally built for Britih military and are constructed using a different physical geometry. Tube fanatics call it the box plate, because the plate structure is a rectangle when looked at cross section wise. Grid windings are different, too, extremely fine and barely visible to the naked eye, although electrical characteristics are identical to a 12AX7 or ECC83.
Obviously they were manufactured with a slightly different 12AX7 characteristic in mind
Most Mullard consumer 12AX7's had a plate structure which was pinched at the ends. I have seen a few 4004's in consumer boxes and label ECC83, however
YMMV and FWIW
'Mullard CV4004 were originally built for Britih military'
I doubt it , this type has the commercial designator of M8137 so was also used commercially . It is a ruggedised 12AX7 and what you suggest is a common misconception around here . Just because it has a CV number , doesn't necessarily mean it was intended for the military . The UKAEA and GPO , for example , were government organisations that used valves designated this way . CV=common valve
Al
CV=common valve, as in common to all three branches of the British military. Army, Navy and Air Force.
" CV numbers were applied to valves used by the British Services, gradually replacing the Army, Navy and Air Force nomenclature in use at that time."
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
CV numbers are not limited to the forces , it covered a vast array of government ministries... I mentioned the UKAEA as I once cleared out a decommisioned research station of a lot of it's old valves . Instrumentation was updated but their stores still had retained a lot of old stock valves , all with CV designators . Ditto for the post office (GPO) which is now known as BT (British Telecom) who used a phenomenal quantity of CV140 (EB91) . Initially the navy , air force and army all had their own designators which were amalgamated during WW2 , hence the CV 'common valve' designation . 'A' datecodes started in 1945 . This eventually covered all government sourcing valves post war . Some people believe that valves with CV designators are better or 'mil-spec' which is a very common misconception .Al
Edits: 10/17/14
Hopefully not to steal the OP thread, but I could use some advice as well. I'm running Quicksilver Silver 88s with KT 150 output tubes into SF Elipsa SE. I'd like to find tubes that have articulate bass extension, partly because I often listen at low levels where the woofers are inefficient and partly I like that musical emotion anyway. I am now enjoying some input tubes I got from Brent Jessee; RCA NOS grey plate 12BH7 and Amperex Bugle Boy NOS 12AX7. The sound is damn good, and much more pleasing than the some re-issue tubes I tried. The only criticism is that I'd appreciate more coherent sound staging, but not to sacrifice bottom end tonality. Now I'm thinking to stock up a replacement set for a rainy day, and wondering if to try something else. Brent only seems to have the RCA 12BH7s although I ought to try the black plates next time; and there are some unmatched Brimar 12BH7s on eBay that I'm curious about (item 310871915920).
For the 12AX7, Brent is offering some Mullard longplate halo getter ($325) and square getter ($475)...hmmm or the same eBay seller as the OP's purchse has them both for less (I figure with Brent I'm paying the premium for selection service). And last, there's some unmatched Genelex B759 on eBay that will probably net a fortune.
Thanks for the input!
Here's the link to the eBay Brimar 12BH7s, and the seller says he will match into pairs, so I wonder about those vs. RCA black plates. For any of these like the square getter Mullard 12AX7s on eBay, I'm clueless on how to read those test stats to determine tube condition, and could use some pointers.
- thanks in advance!
Are you running?
Preamp is solid state, a Hegel P30. It's clean and neutral, kinda like I found in the Quicksilver Silver 88s. I had a tube pre-out DAC (AMR DP-777), and the sounds were close, but I had reliability problems with the AMR. The Heel is not without a problem though, and that's the remote jumps in big db steps... I wouldn't have bought it had I demo'd the remote. Source are FLACS and DSD from a SoTM Zuma CAPS music computer into a Hegel HD25 DAC (strong, warm sound).
Shucks , with a tube amp like a Quicksilver thought you had a tube preamp and sometimes rolling tubes there is more helpful.
Sorry not familiar at all with the Hegel
Thanks ok, the Hegel is very neutral... so much so it derailed my notions of getting a tube preamp. Anyways, I'm not necessarily looking for a big change in the sound, just want to stock up on a set of tubes that will project a good soundstage and have articulate bass extension.
Wondering about Brimar 12BH7 vs. RCA Blackplate
Wondering about Mullard 12AX7 square vs. halo getter
Thanks!
I guess I should have asked this question before I spent my money. Is there a big difference in performance?
Did you buy
http://www.ebay.com/itm/MULLARD-ECC83-12AX7-VINTAGE-VALVES-TUBES-TEST-100-AS-N-O-S-/361079012149? I'm not sure if I'm allowed to do this.
I can't capture the full address but this is most of it.
It's a guy in England, dr-tron and he has a whole heap of them. I guess they are pulls from some factory equipment. On reading the ad it does not specify exactly what they are.Perhaps someone with more knowledge than I can tell from the picture what we have.
I've spent the afternoon educating myself. Something I should have done before I pulled the trigger, ah well.
Edits: 10/15/14
Ah....you got short plates since all are after 1960 .
CV4004 were a separate production run and made IIRC up to the end of the Mullard factories c. 1985. They have a warmer balance and among the best of the Mullards in midrange and bass.
Long plates were built from 1954 to 1959. The plate structure is 17 mm long.
1954 to 1957 marks the first series mC1 (acid etched code on glass)
1957 to 1958 is the f91, my personal favorite
1958 to 1959 is the f92
from 1960 on, Mullard 12AX7's are short plates, 15 mm long and the acid etched codes start off I61, I63, etc....
You got the later short plate series which are still nice tubes and the prices if tubes are checked good, are reasonable, IMHO.
I'm going to put them in my EAR 834P hoping they will give me a little more clarity. Problem is my hearing is no where near as good as it used to be and cranking up the volume only destroys it more.
I need a huge soundstage where the instruments/vocalists are well seperated then I can hear whats going on.
I'm in the middle of regrading my system, I don't know if it's going up or down, time will tell.
You can put the linked address into "Optional Line URL" slot, below. And enter a Link Title. Like this...You may want to wait a bit, as I'm in the process of testing some Brimar CV4035 (12AX7 type) and CV4033 (12AT7 type)--- that Tubemonger sent to me.
Just a thought...
Edits: 10/15/14
What did you think of those Brimar 12AX7? I was looking for info on Brimat 12BH7s...
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