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I don't have new ones {6bl8) but I might have a replacement. I am looking for an exact sub. TIA, dak
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DAK,
Here is a chart of the tubes interchangeable with the 6BL8:
6GH8, 6U8, 6BL8, 6EA8 ratings
Tube....Pentode Trans.....Power...Triode Trans....Power
6GH8.....8500 umhos......2.5W......7500 umhos....2.5W
6U8......7500 umhos......2.5W......5000 umhos....3W
6BL8.....5000 umhos......1.5W......6200 umhos....1.7W
6EA8.....6400 umhos..... 3.1W..... 8500 umhos....2.5W
The 6GH8 has the highest output and was common as a television tube and is said to be found as low quality when marked as a TV brand.
I have a McIntosh MR67 tube tuner that uses a a pair of 6BL8's a s a "pre-preamp" output tube and the sound is fantastic. The 6BL8 European designation is ECF80 and there are premium version E80CF and military version 7643. Ten years ago , since none of these types were in production, I decided to try a few. As they were inexpensive,- some were $2 or so, I ended up with:
6BL8 /ECF80 /E80CF /7643
2- Telefunken E80CF- gp- NOS -
4- Philips Miniwatt ECF80-- Brazil- NOS -
4- Valvo E80CF Red lbl, pinch waist- gp-DE- NOS
2- Philips SQ E80CF - Germany, gp-USED-TNOS -
4- Philips SQ / Mullard- E80CF- disc gtr- UK- NOS
3- Siemens by Telefunken 7643- s.gtr - gp- DE- NOS
3- Amperex PQ E80CF-gp-Hamburg-db.gtr-NOS 64-
5- Siemens & H by Telefunken E80CF- gp- - NOS
4- Amperex PQ 7643- gp- Hamburg- db.gtr s- NOS
4- GE ECF80 -UK - NOS
2- RCA 6BL8- US - NOS
3- RCA ECF80 -France- NOS
1- Sylvania 6BL8- US
It turned out that were really two basic kinds, the Philips / Amperex / Mullard have two substantial triangular getter supports and the Telefunken / Simens design looks more like a conventional triode. I found I much preferred the sound of the Philips design and use a pair of Valvo E80CF pinch waist, gold pin in the MR67, but the ordinary while label Valvo Amperex are all fine. Very low microphonics and a great soundstage. I used to listen to the MR67 in mono and the sound was just astounding and even imaging was incredible- narrow, but deep, deep deep suggesting very good phase coherence.
I liked the sound of 6BL8's so much I looked to see if there had been any preamps that used them as a gain tube.
Cheers
Bambi B
Oracle II_SME V_AQ 200 / MCintosh MR67 /Cambridge Audio 640C v2 > Audio Research SP10 > Audio Research D115 > Vandersteen 2C (AQ King Cobra IC / AQ Rocket 88 speaker)
Hi Bambi, that is great info. Actually, I found your original post on another site and have it bookmarked for future reference. Now, I all I need to do is find where I put those danged E80CF tubes. I know I put them in a little box, I just hope I labeled the outside of the box. cheers, Dak
6LN8 is a near-exact substitute. 6U8 and 6GH8 are usually close enough, and are most common. Plenty of others in the same pinout, 6EA8, 6KD8 and there's a 7199 equivalent: 7687. The direct-coupled circuit often used can be touchy, sometimes it's necessary to adjust screen or cathode resistors for an optimum operating point. The paraphase circuit that Scott used may be less picky.
AFAIK, no pentode/triode types are being produced anywhere. :> ( Everything is NOS.
Compare the data sheet for Russian 6Φ1П (6f1p) to that of the 6BL8. ;> )
New Sensor has access to all sorts of Russian engineering info. I'd like to see NS reintroduce production of the 6Φ1П. Heck, for all I care, label the tubes 6BL8. If this type was reliably available, all sorts of older equipment could be reworked to be indefinitely in service. :> ) Changing from 7199s, 6GH8s, 6U8s, etc. is easy enough. New designs would become feasible too.
Eli D.
mt
Hi FL, that is great, I got some E80CF , around somewhere. I also found some info from AK about subbing 6GH8 and 6U8 for the ECF80. Cheers, Dak
Look at Scott schematics. That sort of substitution rates to work.
Eli D.
Hi Eli, in fact, I am building a Scott 299 clone. What do you mean "...rates to work..."?
Edits: 10/01/15
Take a look at the 299D schematic. Notice either 6U8 or 6BL8.
The 299C schematic shows either 6U8 or 6GH8.
Eli D.
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