[mab1376]

  Hi mab 1376,
 
I have noticed that some of the 6DT6 tubes run hotter than others, both as pairs among different brands, and as individual tubes from the same brand. As a rule, after the initial burning in period the tube runs cooler. IMHO it does not not matter if one tube feels hotter than the other, as long long as there is no sonic difference.
 
Same thing about one tube glowing stronger than the other. Usually it is a function of how the internal parts were put together, and in one tube it may be more difficult to see the heater than in another. Unless the sound is effected, it does not matter.
 
How do you like the Raytheon 6DT6A tubes? The ones I have are made in Japan by Hitachi and sound best on the 2/7 strap setting. They also sound good unstrapped.

 
They are the Japan tubes, i'll try on 2-7 when i swap back to EF95, trying out my 6AV6 currently.

 

[TrollDragon]

I have 4 of the Japan CGE 6DT6's inbound and a pair of those NEC 6AV6's as well. Still waiting on the USAF's, hopefully this week along with my new headphone jack.

 

[MIKELAP]

Listening to some Admiral 6DT6A tubes on EF92 and  EF95  seems cleaner sounding on EF92 setting. by the way you are strapping EF-95 1-7 which setting is  the 2-7 for ?

 

[gibosi]

This week, I found a couple small packages in my mailbox:
 
A pair of Raytheon 6EB6W - (no dates on the tubes or the box)
 

 
Based on Acappella11's recommendation, I purchased these Raytheon 6BE6W. While I have managed to burn them in, I haven't really had time to do any critical listening and comparing.  As my headphones are not as bright as A11's, I find that the more forward sound of 2/7 is best for me. They are very transparent, somewhat warm, with nice "heptody" highs and some of the best bass I have heard out of a heptode. Very nice.
 
And a pair of Canada General Electric JLRV 6AT6 (1965)
 

 
Appearance wise, these are very different than any GE 6AT6/6AV6 tubes I have seen to date. However, these tubes do look almost identical to Audiofanboy's Pinnacle 6AV6.
 
AFB has compared pictures of these CGEs to his Pinnacles and he tells me that the glass envelope as well as the innards - micas, plates, diodes - look virtually identical. Further, while these have been cooking for less than two hours, they appear to have a very high level of clarity and transparency, mids that are more wet and musical than most 6AT6/6AV6, and BASS! which correlates well with AFB's Pinnacles. I think it is quite likely that his Pinnacles and these CGE were manufactured in the same factory. But if so, where that factory might have been located is still a mystery. If they really were manufactured in Canada, who manufactured them? Might these too be Japanese imports?

 

[mordy]

Hi Gibosi and AFB,
 
What do you say about the right tube in this picture? It is a Raytheon made in USA.
 

The plot thickens...

 

[gibosi]

Interestingly, the left-hand tube appears to be a rebadged RCA.
 
And here you see something similar from Raytheon: A rebadged RCA on the right and a tube that seems to to resemble the CGE/Pinnacle on the left. However it is not clear that these mystery tubes were actually manufactured in the US. It may well be that Raytheon acquired them elsewhere and simply relabeled them......
 

 

[Oskari]

And a pair of Canada General Electric JLRV 6AT6 (1965) ... Appearance wise, these are very different than any GE 6AT6/6AV6 tubes I have seen to date. However, these tubes do look almost identical to Audiofanboy's Pinnacle 6AV6. ... If they really were manufactured in Canada, who manufactured them?

 
They do look the same! Radio Valve Co. of Canada.
 

1. http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/795#post_9222915

 

[Audiofanboy]

I can confirm that they look exactly the same as my Pinnacle tubes. Mystery may be solved...?

 

[Iron58p]

Today are arrived 7 couples of tube, all in the same day

 
Voskhod 6J1P-EV (EF95 6F32 6AK7) Gold-Platinum grid ( matched ) year 1982 ----------(EF95)        One channel has a noise, i hope that finished burn in, noise will desappear.
 
Siemens 6AK5W (M8100, CV4010,5654) ------------   (EF95)
 
RCA JAN 6AV6--------------(EF92 and cut pins 5 and 6)
 
GE JAN 6AV6------------- (EF92 and cut pins 5 and 6)
 
SYLVANIA 6BE6 (EK90, CV4012, 5750)------------- (EF95)
 
For all tubes in this post, without strapping !!
 
 
 
 
About the 2 couples below, i don't know anything, for example if i can use it without strapping or cut pins ( for the moment i'm not ready to strap )
 
GE 8425A (6AU6A)------------(EF95)
 
Tung-Sol JTL 6AH6WA (6J5P, 6485)------------(EF95)
 
Is all correct ?
 
Thank's

 

[gibosi]

  Today are arrived 7 couples of tube, all in the same day

 
Voskhod 6J1P-EV (EF95 6F32 6AK7) Gold-Platinum grid ( matched ) year 1982 ----------(EF95)        One channel has a noise, i hope that finished burn in, noise will desappear.
 
Siemens 6AK5W (M8100, CV4010,5654) ------------   (EF95)
 
RCA JAN 6AV6--------------(EF92 and cut pins 5 and 6)
 
GE JAN 6AV6------------- (EF92 and cut pins 5 and 6)
 
SYLVANIA 6BE6 (EK90, CV4012, 5750)------------- (EF95)
 
For all tubes in this post, without strapping !!
 
>>>>> Yes you can use all of these without strapping. 
 
 
About the 2 couples below, i don't know anything, for example if i can use it without strapping or cut pins ( for the moment i'm not ready to strap )
 
GE 8425A (6AU6A)------------(EF95)
 
Tung-Sol JTL 6AH6WA (6J5P, 6485)------------(EF95)
 
Is all correct ?
 
>>>>> You cannot listen to these without strapping 2-7. They absolutely must be strapped.

 

[Iron58p]

All clear, thank's.
 
Any kind of metal is ok ? i now that must be thin.... an electric cable with copper inside is ok ( isolated in the middle ) ?

 

[gibosi]

Canadian GE 6AT6 (and Pinnacle 6AV6)
 
After spending some time with these tubes, it is my opinion that these are essentially RCA 6AT6/6AV6. With the exception of the diode plates, they are virtually identical. Moreover, they sound virtually the same.
 
It is a little funny that the diode plates are the most noticeable feature of this family of tubes and we tend to focus on this feature when physically comparing them. But of course, the diode and triode circuits are entirely different and separate, and moreover, by cutting pins 5 and 6, we effectively disable the diode. So while the diodes in these two tubes are slightly different, the glass envelope, the micas, the triode plates and the getters are virtually the same. And thus, I believe these are simply black-plate RCAs.
 

 

 

[gibosi]

  All clear, thank's.
 
Any kind of metal is ok ? i now that must be thin.... an electric cable with copper inside is ok ( isolated in the middle ) ?

 
Yes, stranded cable, smaller than 26 gauge, equivalent to (.04mm and .134mm²)

 

[Oskari]

  But if so, where that factory might have been located is still a mystery.

 
BTW, this seems to have been the location of RVC on Dufferin Street in Toronto. 

 

1. http://wikimapia.org/#lang=en&lat=43.636735&lon=-79.426056&z=17&m=b

 

[kvtaco17]

Got a pair of OPA627's yesterday... very similar to the TI OPA2107, but with much improved channel separation, slightly bigger sound stage, better instrument separation... so far  it sounds kinda like a hybrid love child of the OPA2107 and LME49990... I like it a lot!
 
 
I also received the GE 6DT6 (grey plates and ribbed) Svetlana 6A2P (looks a lot different in construction vs other heptodes I've deal with) AND a new to me AD2000X (amazing cans I must say!)
 

GE 6DT6
 

Sylvania, RCA, GE 6DT6 comparison
 

More of the same...
 

Svetlana 6A2P
 

Svetlana with its Ediswan and Valvo cousins...
 

OPA2107 and OPA627
 

OPA627 installed!