[kuma]

Quote:

Originally Posted by Jahn you'd probably really dig a 7308 in your rig then - system matching is key!

Those were too lean!

 

[Len]

7308 is simply a culled 6922, not some special design. You shouldn't be hearing big differences if it's the same principle design. I think we're all better served if we discuss these tubes by their internal construction like adhoc did, not merely by their alpha-numerical designations or prints (especially for 6dj8/6922/7308/cca line of tubes). I presently have no less then five iterations of Siemens Cca, for example.

FWIW, I've never heard an Amperex-made 6dj8/6922/7308 sound lean. My current theory is their particular metallurgy lends to warmish, full tones.

 

[kuma]

len,

I just try bunch of them and use the ones suited for the rig.
But certain tubes do have specific sonic signature whatever the reason.

So, what is my current fave Tungsram E88CC?
Is this simply another variant for a 6922 i take it?

funny thing is that Seimen's E88CC ( pictured ) sounded aweful.

What are you using on your jotas?

 

[Len]

E88CC is the european designation for 6922. So, E88CC=6922.

I'm using the early 1960s Siemens CCa in my Jotas. The strange thing is I find Tungsram most similiar to Siemens then any other 6DJ8-type tube.

 

[kuma]

Yeah. CCa is good.
They are my back ups for Jotas. ( my second pair )

Too expensive for day to day use tho.

These Tungsrams have more body than the Cca which came in handy when I switched a preamp and the source.

 

[adhoc]

ECC88/6DJ8 - original tube type
E88CC/6922 - "industrial" grade selected 6DJ8 tube
E88CCa - selected E88CC tubes for German post office use in public address systems. also known as simply "CCa".
E188CC/7308 - higher specc'ed version of the 6DJ8. means that you cannot subst in a 6DJ8/6922 in a circuit that needs a 7308.

...this all is an extract from my upcoming thread/archive of 6DJ8 type tubes.

Remember my 6SN7 archive thread? I'm currently working on one for 6DJ8 types - PROJECT NOW CANCELLED.

 

[Jahn]

Don't forget the 7DJ8 then too - my Amperex 7DJ8s were beasts before one blew.

 

[Len]

Quote:

Originally Posted by adhoc ECC88/6DJ8 - original tube type E88CC/6922 - "industrial" grade selected 6DJ8 tube E88CCa - selected E88CC tubes for German post office use in public address systems. also known as simply "CCa". E188CC/7308 - higher specc'ed version of the 6DJ8. means that you cannot subst in a 6DJ8/6922 in a circuit that needs a 7308. ...this all is an extract from my upcoming thread/archive of 6DJ8 type tubes. Remember my 6SN7 archive thread? I'm currently working on one for 6DJ8 types.

I have never read in any tube manuals that a 7308 is a higher spec'ed 6DJ8. Yes, the 7308 is spec'ed for more heater current then a 6922 (which was deliberately rated for less), but a 6DJ8's specified ma is 365, exceeding the 7308's 335ma. All other electrical properties are the same. For al intents and purposes, all three of these tubes can be used interchangably with no problems.

 

[adhoc]

Quote:

Originally Posted by Len I have never read in any tube manuals that a 7308 is a higher spec'ed 6DJ8. Yes, the 7308 is spec'ed for more heater current then a 6922 (which was deliberately rated for less), but a 6DJ8's specified ma is 365, exceeding the 7308's 335ma. All other electrical properties are the same. For al intents and purposes, all three of these tubes can be used interchangably with no problems.

Len, my sources mention that the 6dj8 is rated for 180V plate voltage and 1.5W max plate dissipation. the 7308 for 250V and 2W max plate dissipation.

It's still a work in progress - don't shoot the messenger!

 

[Len]

Didn't mean to shoot the messanger

Just wanted to collaborate data. Borrowed from tubeworld:

Quote:

6DJ8 ELECTRICAL DATA: --------------- MAX RATINGS: ----------- Heater voltage 6.3V Heater current 365mA Max plate voltage (Ia=0) 550V Max operating plate voltage 130V * Max plate dissipation 1.8W Max plate current 25mA Max grid voltage -50V TYPICAL OPERATION: ----------------- Heater = 6.3 Heater Current = 365ma Vplate = 90V Vgrid = -1.2V Iplate = 15ma Rplate = 2650 ohms Gm = 12500 Mu = 33 -------------------------------------------- 7308 ELECTRICAL DATA: --------------- MAX RATINGS: ----------- Heater voltage 6.3V Heater current 335mA Max plate voltage (Plate current = 0ma) 400V Max operating plate voltage 220V Max plate dissipation 1.5W Max plate current 20mA Max grid voltage -100V TYPICAL OPERATION: (for 10,000 hour life) ----------------- Heater = 6.3 Heater Current = 335ma (range is 318ma - 352ma) Vplate = 100V Vgrid = -1.2V Iplate = 15ma Rplate = 2650 ohms Gm = 12500 (Gm under 9000 would be towards end of life) Mu = 33 Pa Max = 1.5 watts

So your source is correct: the 7308 is rated for higher plate voltage, but if you drive it at the higher plate voltages, the tube won't last very long. One is rated for more voltage, the other for more current. The 6DJ8 has the higher dissipation.

Basically, I've never run across a situation where any three of these tubes were not safely interchangable.

 

[Patu]

Quote:

Originally Posted by Jahn ...

I didn't like US made Orange Globe 7308 at all. They have weird soundstage. Vocals were like extremely center of my head but then again otherwise the soundstage was quite wide. I can't explain it better but it just sounded weird.

 

[Jahn]

interesting stuff! my grados love current, so the fact that i like the 6DJ8 more than the 7308 might have something to do with this? hmm!

 

[nurxhunter]

Joes Tube Lore is absolutely spot on here.

Another good post is:

http://home.att.net/~chimeraone/6dj8sound.html

My impressions with EMP and HD650/Cardas. Cal Alpha Tube DAC. High bit MP3s on HD. Cardas NR, 0.5 M.


1.Amperex 6922. US. PQ White Label. Early-Mid '60s. Shield/Halo. A real winner. Does everything #5 does, but warmer mids and fuller bass. Wonderful. Matches well with any 12AT7, and any can. My top choice based on sound and value (with #5 almost as good sound and much better priced). Not so rare--yet.

2. Brimar/Mullard E88CC. UK. Dimpled disk getter. 7L1 code. Early60's-early '70s. Like #1 above--but warmer and lusher. Excellent vocals. Good bass. Not as much top extension. I'll bet perfect for Grados. I love 'em with HD650 as well. Pair with a precise early German 12AT7, or Brimar black box plate 12AT7WA/6060. Pretty rare.

3. Philips E88CC. Dutch. Early-mid '60s. Like #1, but lusher. More forward vocals, less top end extension and air. Great impact and a great tube. Pretty rare.

4b. Amperex 7308. US. PQ White Label. Early-Late '60s. Like #1. More detail, but leaner in mids. Great tube. Worth about $100/pr. Maybe--life is short. Not that rare--yet. I have some 1960 D-getter coming--maybe I'll change my mind and uprate this.

4a. The Dutch E188CC sounds like a hybrid of #3 and #4b. I prefer it to US 7308 for its warmer mids and fuller impact. Its a US 7308 with more forward, richer vocals. EXCELLENT. Pretty pricey. Pretty rare.

5. Amperex ECC88: Dutch. Orange Globe, late 60's, shield/halo getter. EXCELLENT. Linear, neutral, precise. Mids a bit cool--but nice. Very detailed. Great impact. Matches best with 'warmer' tubes (like British 12AT7 or even early Bugle Boy 12AT7). BEST VALUE. START COLLECTION HERE. INEXPENSIVE REFERENCE.

6. Amperex ECC88: Dutch Orange Globe, early 70's, shield/dimpled disc getter. VERY GOOD. Like above--but softer highs--though as detailed. A smooth EXCELLENT tube--maybe a little 'veiled'. I think this was only made from '69-'71. Transition between #5 and #7 in Amperex history--and sounds exactly between the two. Pretty rare, actually.

7. Amperex ECC88: Dutch. Orange Globe, early 70's, A-frame/dimpled disc getter. Very good. Like #6, but more dimensional. Can sound 'hollow'. Wide stage. Very forward vocals. Kinda 'echos'. An amusing and nice tube. Maybe the most veiled--but maybe not a bad thing as this one is actually VERY popular in the Orange Globe series.

8. Amperex Bugle Boys ECC88. Dutch. Early-Mid '60s. Warmest of all. Like #3, but warmer, richer and not as refined. Not as detailed. Might be wonderful with Grados--a bit too lush for HD650. This is an excellent tube as well--it's certainly not last on the list--maybe right behind #5 or right with it depending on taste?

I just scored a nice pair of Siemens 7308--supposedly the best Siemens type according to many. I'm looking forward to it. 1965--VERY rare. I may pick up some TFK E88CC GP (not so rare) to complete the audio tour of the major 6DJ8 flavors--which as above are all very tasty!

Generally, the prices reflect supply and demand--and also perceived sound quality. The 6DJ8 tube market is possibly the most efficient of all tube markets? You get what you pau for--but--from late '50s to early '70s--Philips/Amperex/Mullard/Siemens did not make any bad 6DJ8s. They all sound good to outstanding--and--they all sound distinctly-to-subtly different, as above.

The ECC88/6DJ8 all have steel pins. The others above all have gold pins, which appear not to corrode over time--not just a trick. The Germans and Dutch apparantly took the 6DJ8 VERY VERY seriously. This is the last great effort by tube manufacturers to out do one another. Except for Amperex on Long Island NY, the US majors were going downhill and do not compete here AT ALL. All the EU and US AMperex tubes are very high quality and sound consistant by label within types. Section mismatch not as great as with other tube types. Even the labels seem to last longer, even from early years.

 

[Hirsch]

Quote:

Originally Posted by nurxhunter /img/forum/go_quote.gif The ECC88/6DJ8 all have steel pins.

All but one. The Mullard 10m ECC88 has gold pins. Very similar to IEC/Mullard 6DJ8's in appearance, but they come in a nice purple box, foam padding, two year warranty on box flap. I was lucky enough to stumble into a pair of these NIB. They're not common. I can't decide whether to put them into an amp now or save them for something really special.

 

[jamato8]

I have many of those in NOS and what amazed me was some 6DJ8's from Amperex, after they quite making them, that are Russian. They are a variant but are labeled 6DJ8 and man do they sound fine. I prefer them in all areas to other types except my RCA branded Siemens gold pin 6922. The Siemens isn't better just different. I also really like the 1965 6N1P black plate but then I say this all the time.