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In Reply to: RE: the 6DJ8/6922/7308 family posted by jmkochevar on April 30, 2014 at 09:11:37
jmkochevar,As an audio Research SP10 owner since 1987, I sympathise completely with Audible Illusion addicts- it seems that the best sound from the 6DJ8 family is made when they are pushed over the limit. I went trough a number of very good Amperex ECC88's, that produced a beautiful sound- but only for 10 hours.
The best summary of this tube group for evaluating ruggedness that I've found is>
6DJ8 ratings:
ECC88 = 6DJ8 _ 130V / 1,8W
E88CC= 6922 _ 220V / 1,8W
E188CC= 7308 _ 250V/ 2W
6H23p Sovtek 6922 _ 300V/1,8W
6H23p-EB EH 6922 _ 300V/2W
- where it's possible to see that each designation has a different rating for V's and W's handling. The E188CC and the Russkoid 6H23p-EB are the toughest.
At the time I had extreme troubles finding suitable tubes for the SP10, I found this useful guide to new and NOS tubes for the Audible Illusions preamps of the time >
Audible Illusions (5 KB)
[ Home ] [ Technical & FAQ ]
Technical bulletin #5
RECOMMENDED BRANDS OF TUBES
FOR MODULUS SERIES 2 & SERIES 3 PREAMPLIFIERS
NEW TUBES - Currently installed in M3A and L2 preamplifiers
6922 SOVTEC, RUSSIA - GREY PLATES
Currently imported from our sources in Europe, these tubes have excellent sonics, low microphonics and distortion.
6H23EB RUSSIAN MILITARY, RUSSIA - GREY PLATES
Most are NOS currently imported from our sources in Europe. Similar to 6922 Sovtec "Grey Plate" tubes. Closely resemble tubes installed in Modulus, series 2 and 3 preamplifiers between 1988 & 1996. Excellent sonics and reliability.
NEW TUBES - Recommended, but with some reservation
E88CC JJ ELECTRONIC, SLOVAK REPUBLIC
Excellent sonics but somewhat microphonic. Similar tooling to classic German Amperex installed in Audible Illusions and Audio Research preamplifiers in mid-1980s. New tubes have approximately 50% rejection rate for excess noise and microphonics. Inexpensive, worth the trouble to sort/select. Ideal line stage tube.
ECC88/6DJ8 - ELECTRONIC INDUSTRIAL, YUGOSLAV/SERBIA,
A-FRAME DIMPLED RING GETTER
Tube installed in Modulus series 2 preamplifiers in mid-1980s. Similar to tube manufactured by Phillips-Holland in the 1970s for Amperex. Sweet sonically. Most are very microphonic.
6922 SOVTEC - RUSSIA, MFG. BY REFLECTOR - PLATES PARTIALLY UNCOATED
Current production Sovtec tubes currently used by several tube preamp manufacturers. Initially this tube checks out OK but many prematurely fail due to poor construction. Has noticeable midrange glare when compared to "Grey Plate" Russian tubes.
NEW-OLD-STOCK TUBES - From our extensive tube library we recommend these NOS tubes with some reservation.
Ranking in order of reliability in Modulus preamps.
1- 6922 AMPEREX, GERMANY, SHIELD WITH RING GETTER
Installed in Audible Illusions, series 2 and Audio Research SP8 and SP10 preamps in the mid 1980s. Very open-dimensional sonics. Excellent reliability but most tubes microphonic. One of the finest sounding preamplifier tubes ever made.
2- E88CC TUNGSRAM, HUNGARY, SHIELD WITH RING GETTER
Excellent sonics but somewhat microphonic. Good tube life. Very popular tube for current production Modulus preamps.
3- 7308 SIEMENS, GERMANY, SHIELD WITH RING GETTER, GOLD PINS
Somewhat microphonic but performs well in A.I. preamps. Excellent line-stage tube.
4- E88CC SIEMENS, GERMANY, SINGLE RING GETTER, GOLD PINS
Excellent sounding tube. Sounds like a cross between a good Amperex and Tungsram. Somewhat microphonic.
5- ECC88/6DJ8 AMPEREX BUGLE BOY, HOLLAND, SHIELD WITH RING GETTER
Hard to find and expensive. Excellent sonics with sweet top end. Manufactured for Amperex in the 1960s and early 1970s. Somewhat microphonic. Probably the finest sounding preamplifier tube ever made. *DO NOT confuse with "rebranded" Sylvania 6DJ8’s currently sold by Richardson Electronic.
6- ECC88/6922/7308 AMPEREX PQ, HOLLAND, SHIELD WITH D-RING GETTER, GOLD PINS
Rare. Very open-uniform sound. Somewhat microphonic. In mid-1980s Gold Aero was branding them 7308’s and selling them for $50 each. Excellent line stage tube.
7- ECC88/6DJ8 AMPEREX, HOLLAND, A-FRAME DIMPLED RING GETTER
Manufactured for Amperex in the 1970s. Same tooling as EI-Yugoslavian tube but superior workmanship. Sweet sonics, somewhat microphonic.
7A- ECC88 MULLARD, GT.BRITAIN, A-FRAME DIMPLED RING GETTER
Same tube as above. Manufactured for Mullard by Philips-Holland in the 1970s.
8- 6DJ8/ECC88 AMPEREX, HOLLAND, SINGLE RING GETTER
Tube actually manufactured for Amperex by Matsushita/Japan during the late 1970s and early 1980s. Installed in early A.I. Modulus series 1 preamps, this tube has a very sweet-uniform sound. Somewhat microphonic.
9- 6DJ8 MULLARD, ENGLAND, SINGLE RING GETTER
Similar tooling compared with Matsushita/Japan tube but manufactured by Philips-Holland for Mullard. Sweet sounding tube but most have excessive microphonics.
10- ECC88/6DJ8 ZAEREX, RUSSIA SINGLE RING DISH GETTER
Tube used almost exclusively by Counterpoint Electronics in the 1980s. Quiet-smooth, low microphonics but somewhat fat bass response. Has a tendency to oscillate in early Modulus series 1 and 2 preamps. Do not use these in older A.I. models.
Tubes with questionable sonics and unacceptable technical performance
NOT RECOMMENDED for Audible Illusions preamplifiers
6DJ8H CHINA, SHIELD WITH FLAT-SQUARE GETTER
Plates only partially coated. Tube has glassy sound and unacceptable microphonics.
6DJ8 SYLVANIA-USA, SHIELD WITH RING GETTER
Tube has uneven sonics and midrange glare. Most are microphonic. Currently being re-labeled with Amperex "Bugle-Boy" logo and sold for high price by Richardson Electronics.
6DJ8 PHILIPS, USA, JAN/JOINT ARMY NAVY
*Same as above.
In the SP10, while ECC88 were more open and natural, I eventually gravitated, for reasons of ruggedness in combination with sonics, to Valvo E188CC's for the gain tubes and Tungsram Red Label (military) E88CC for the followers, splitters, etc. The Tungsram, which are a Siemens E88CC-based design are very well made, with excellent section matching and to me too good sounding for followers and the like. I eventually bought 28 NOS.Cheers,
Bambi B
Edits: 05/01/14 05/01/14 05/01/14 05/01/14Follow Ups:
thx for your 'war and peace' response ;) ;) looks like the combo of more voltage(sorry jimmy mac) and higher wattage works out for the AI's.
i've tried the red label tungsrams and they're clean sounding and dead quiet...but i'm looking for a little more mid-range lushness/fullness. i'm probably headed for red valvo e188cc's of 1963 vintage (VR6)...they're re-branded amperexes which are close enough to the tubes that wood1 earlier recommended.
jmochevar,
RE: "War and Peace response" : Those on this site who know me from earlier times- (starting I think in 2000 or 2001), that I never use one word when twenty will do just as well.
I am pleased that Jim McShane so succinctly clarified the Watts /dissipation aspects as the key parameters to evaluate tube ruggedness.
The Tungsram E88CCs are for me similar to the Siemens upon which they are patterned, and as you mention very quiet, but I also ended up using Valvo E188CC in the positions with the greatest influence on the sound. The Tungsram and Siemens do have an admirable accuracy, energy and punch, but the Philips seem to have a more pleasing timbre. Most of the Philips E188CC I have (24) are VR5 and VR9. I have about 100 of the 6DJ8 family and never found a really compelling sonic reason to buy the very early ones.
Cheers,
Bambi B
Main System: Oracle Delphi III /SME V / Audioquest 200, Dual 1019 (78's)/Cambridge Audio 640 v2 , McIntosh MR67 (1965)> Audio Research SP10 > ARC D115 > Vandersteen 2C, Audioquest King Cobra IC, Audioquest Rocket88 speaker, Audioquest NRG 2 power, OneAC 12A isolation transformer power conditioner
"Those on this site who know me from earlier times- (starting I think in 2000 or 2001), that I never use one word when twenty will do just as well."
Bambi, are you sure we aren't related somewhere along the line?? :~)
Jim McShane,
I think we are related in the sense that written descriptions of sound, it's relationship with hardware, and the science behind it does require a careful word choice- and to make a complete and supported description- a lot of words. Your post concerning tube ruggedness was excellent and to me, was clear, accurate, and exactly the right length.
Recommending a particular tube, requires scientific, technological, quantitative, qualitative,and aesthetic language! And, especially the aesthetic language may be confused and seem vague. Think of how many ways a tube might be called "cool".
Personally, I had always thought I would write austere poetry and novels in the magical realism style, but instead I am writing Patent applications- much more difficult to do well,..
Follows is a wordless description of the arcing of a GE 6550A called "Design for a Theatre".
Cheers,
Bambi B
Hi, Bambi, so you are in the patent business I see, done a few applications myself although I am primarily a patent searcher, who are you with?
gkargreen,
Ah- I may have made this sound grander than it is, as these are provisional applications for my own projects, of which there are a considerable number. These are considered preparatory and the hope is that they will represent sufficient protection during a development / funding phase.
I've been doing my own searches too- which seems more difficult to do well. In 2009, after what I believed to be a careful search, I worked on a project for months and only when doing application exhibits found an astoundingly similar design patented two years previously. This was a surprise as it was a complex and somewhat counter-intuitive device. It seems that the unconventionality confused the search- difficult to categorize.
A friend who is retired from NASA and who has several Patents is advising and there is much to be learned from doing searches and reading other applications. Even reading the details of infringement lawsuits is informative.
I've often wondered how professionals learn this as it requires a combination of high density technical, descriptive, and legal thinking.
Required forum audio content> quite a few audio projects including a couple that are vacuum tube related.
Cheers,
Bambi B
" looks like the combo of more voltage(sorry jimmy mac) and higher wattage works out for the AI's."If you mean the tube is capable of handling higher dissipation wattage then that is true. But...
Again, it is NOT the voltage that kills the AI tubes, it's the current and the dissipation. This is not something I'm making up out of thin air. It is the FACTS .
You can put 400 volts on a 6922 - and unless it arcs the voltage will not be a problem AS LONG AS THE DISSIPATION AND CURRENT ARE WITHIN LIMITS!! I'm not saying you should (there are a lot of considerations besides the voltage limit of the tube), but you can.
Do you know what "higher wattage" means? "Higher wattage" in the tube ratings means the tube has a higher dissipation rating. Dissipation is measured in watts. It has to do with the ability of the tube (or other device) to deal with the heat generated.
If a given tube has a maximum dissipation of let's say one watt - it can reach that dissipation limit with any number of voltage and current combinations. All the voltage/current combos listed below yield one watt of dissipation:
1 ma and 1000 volts
2 ma and 500 volts
4 ma and 250 volts
10 ma and 100 voltsAnd so on...
For any given current - if you increase the voltage you will increase the dissipation; if you decrease the voltage you will decrease the dissipation.
For any given voltage - if you increase the current you will increase the dissipation; if you decrease the current you will decrease the dissipation.
The voltage we are talking about is the plate voltage - which is the voltage difference between the plate and the cathode. If the voltage on the plate is 200 volts and the voltage on the cathode is 10 volts then the plate voltage is 190 volts. If the voltage on the plate is 200 volts and the voltage on the cathode is 0 volts then the plate voltage is 200 volts.
Finally remember this - a simple definition for voltage is "potential difference". It may be helpful to remember that you can have voltage without current, but you can't have current without voltage . Even arcing - which occurs when the voltage (pressure) overcomes the resistance and CURRENT FLOWS - just like too much pressure in a garden hose can burst it and cause flow.
Voltage is like the pressure in a garden hose with the hose nozzle shut. There is pressure but no flow. Open the nozzle and you get flow - unless you lose pressure at the nozzle (like if the hose kinks).
Voltage = pressure, current = flow. Current requires electron flow. Voltage does not.
None of the above is my OPINION, it is fact, as dictated by the laws of physics that apply. I don't know everything about physics and electricity, but I do know that what I just posted is FACT. And yes, this is partially a rant, because "sorry jimmy mac" implies I am wrong. I'm not.
Edits: 05/02/14
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