Raytheon 6BG6GA differences??

[ehoove]

Being somewhat of a tube newb, a question for the tube guru's. What is the difference between a Raytheon Uniline Grey Plate 6BG6GA, and a Raytheon Black Plate Version. The black plates have more drive and sound superior (more open and more attack) in my Quicksilver mini mono's driving the ribbons in my Magnapan MGIIIa's.

Regards,
Jim

 

[buglegirl]

Hiya Jim,

Is this a amplifier designed specifically for the 6BG6GA or a amplifier designed for the 6L6GC using adapters ???

Guess what I am going at is there is a wide range of internal differences between 6BG6GA's ... some are really 6L6GC's in disguise. And some are more like 6L6G's or 6L6GB's

Frannie

 

[ehoove]

Frannie,
It is designed for many types including 6L6, and is self biasing. I am using adaptors.
Regards,
Jim

 

[buglegirl]

Hiya Jim,

My guess is that one of the 6BG6GA's is a 6L6GC capable and the other is 6L6GB capable lets say.

So when you plug one in or the other they are either at peak power or down some from peak power.

Maybe a good picture of each might clear up this mystery.

Frannie

 

[ehoove]

Frannie,
I'll try and post a pic or two in the next day or so, I'm really jammed up today with a publishing deadline looming Thursday AM.
Regards,
Jim

 

[Pio1980]

I can't say specifically for Raytheon, but having fooled with 1940s roundy TVs since I was a teen I've seen the main visual differences in the shouldered versions being the presence or absence of ceramic components on the mica parts. I assume those with them came from 807 line tooling. The published screen voltage is nowhere as high as the plate rating on 807 but apparently ignored in many amps using them.

Sent from my SM-N900V using Tapatalk

 

[jaymanaa]

Are they all NOS?

 

[ehoove]

Yes

 

[gadget73]

I can't say specifically for Raytheon, but having fooled with 1940s roundy TVs since I was a teen I've seen the main visual differences in the shouldered versions being the presence or absence of ceramic components on the mica parts. I assume those with them came from 807 line tooling. The published screen voltage is nowhere as high as the plate rating on 807 but apparently ignored in many amps using them.

Sent from my SM-N900V using Tapatalk

Probably the difference is whether its an 807 in an octal bottle, or a 6L6GC in a top-cap bottle. All three are of a family, so its not unreasonable for either to be the case. I believe the 6BG6G originally came from the 807.

 

[buglegirl]

Hiya,

Probably the difference is whether its an 807 in an octal bottle, or a 6L6GC in a top-cap bottle. All three are of a family, so its not unreasonable for either to be the case. I believe the 6BG6G originally came from the 807.

I would think most of the "Repackaged" 807's would have been the 6BG6G's and the later GA's particularly near the end of production could be 6L6GC's in disguise.

Gotta figure anything that is not a ST bottle is either 6L6GB "Like" or 6L6GC "Like"

And this is why I need a expensive "Tube Lab" (Yah I am borrowing the terminology because I am not creative this morning) setup and a bunch of free time.

Or a real life ...

Frannie

 

[ehoove]

Comparison Pics

Here are the promised pics! Grey on the left, and Black on the right
Regards,
Jim

 

[buglegirl]

Hiya Jim,

That Gray Plate 6BG6GA looks identical to a Sylvania 6BG6GA I have here.

So if you connect the dots ... the Philips later Gray Plates are suppose to be 6L6GC's inside (Sylvania Sold Tube Business To Philips)

How do you bias these normally ??

Frannie

 

[Pete B]

I agree gray plate looks like a 6L6GC and the black like a 6L6GB:
http://www.ebay.com/itm/GE-6L6GB-Tu...D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

What is the plate and screen voltage in that amp? The GBs are not rated as high as the GCs.

 

[gadget73]

hm, yeah bigger plate structure and cooling fins on the top of the grey plate one. Would make sense for that to be closer to a 6L6GC spec-wise.

Hiya,



I would think most of the "Repackaged" 807's would have been the 6BG6G's and the later GA's particularly near the end of production could be 6L6GC's in disguise.

Gotta figure anything that is not a ST bottle is either 6L6GB "Like" or 6L6GC "Like"

And this is why I need a expensive "Tube Lab" (Yah I am borrowing the terminology because I am not creative this morning) setup and a bunch of free time.

Or a real life ...

Frannie

Probably so. I keep forgetting that the GA is the straight bottle version. I just automatically think of the 6BG6G in that old ST bottle. Probably because I've got a liking for big ST bottle tubes, they just look cool.

 

[Pete B]

Some say that certain 6GB6s were stuffed with 7027A guts, and I was only able to find those big heat fins on the top in 7027As:
http://www.ebay.com/itm/PAIR-RCA-Raytheon-7027A-power-tubes-New-Old-Stock-New-In-Boxes-/360556047825

 

[whoaru99]

For additional reference, here are a couple pics of the 6BG6GAs that SND has been selling as the "super" variant compatible in dissipation (35W plates) to 6L6GC, 7581A or 7027A.

Mica-to-mica is 38-39mm. They are branded PhillipsECG.

 

[Trio]

The black plate structure looks real similar to 807's I had and sold over a decade ago, and with the sonic differences, that would be consistent. I have used a 6L6 GB and 6L6 GC in a tube amp I built recently for early testing and refinements, and before I tamed the B voltage down, there were no problems redplating, and they did not sound bad at all, but both tubes tested below 40 on a cheap tube tester, so if there were significant sonic differences, that would have been a time when that would have been readily apparent.

Based on other discussions of black versus grey and some of the writeups that are around the web, the black ones tend to be older, and this may explain some of the difference.

Now on the top of add matching, I am actually a running a US 7591 with a coin base Russian made 7591 (6L6GC) that matched quite well on the tester, and it does not sound bad at all in my Sherwood. So I suspect the difference you encountered and in reading the other discussions, your tubes may have the same basic number but are really 2 different animals. If it were mine, I would go with what sounded best and hang on to the other tubes for another amp or a project. And if I needed to, I would look to getting a few more of the black plates. But that is just me.

 

[ehoove]

Hiya Jim,

That Gray Plate 6BG6GA looks identical to a Sylvania 6BG6GA I have here.

So if you connect the dots ... the Philips later Gray Plates are suppose to be 6L6GC's inside (Sylvania Sold Tube Business To Philips)

How do you bias these normally ??

Frannie

The quicksilvers are auto biasing.
Regards,
Jim

 

[ehoove]

The Greyplates are branded Raytheon Uniline, but the Black Plates are straight Raytheon branding??
Regards,
Jim

 

[gadget73]

Any other numbers on there? There is often a 3 digit code that will tell you who really made it. Raytheon did make their own tubes, but its not impossible that they are made by someone else and branded for Raytheon. The grey plate one does look like Raytheon numbering.

Not totally sure on the other one but I have a feeling its a GE made tube. Looks like I see the sand-etched dots that are consistant with GE tubes. A "188" somewhere on the glass or base would tell the tale.