Can you help me with Bugle Boy date codes

michaeljhsda2

I pulled all these tubes from a Harmon-Kardon receiver (1958?) and I'm having a hard time figuring out the date codes. I'm guessing they are probably not older than 1958 but what do I know... Thanks for any input you can give.





In this photo the 12AT7 is on the left with the two 12AX7's to the right of it.

michaeljhsda2

another view of the 12AX7's

george daniel

Usually Amperex date codes are etched on the side of the glass,,near the bottom,,here's a link that mey help

http://www.audiotubes.com/mullcode.htm

michaeljhsda2

Great. Thanks a lot George.

george daniel

did it help?

michaeljhsda2

Finding the link was a breeze LOL but I what I'm having a hard time figuring out is do I try to decipher the numbers/letters on the bottom of the tube as well as the numbers on the side? On the bottom is mC1 D7E so my guess is 1957? On the side my guess is July 1949. There's a lot to read on that site so this may take awhile. Sucks being a newbie.

george daniel

Look closely on the side of the tube--their shoud be a date code/etching like (delta symbol and some numbers),,I just looked at one of mine and I had to use a magnifying glass--handle them easily,cause the date code may be printed and it's easily removed considering the age of the tubes.

michaeljhsda2

Will do..brb

george daniel

http://www.audiotubes.com/12ax7.htm

http://www.triodeel.com/images/philipstubecodes.pdf

michaeljhsda2

I looked very closely and I didn't find anything, no delta symbol, etc. Could the date code be the 7 and then there is a 49 under that, as seen in the last photo I posted?

george daniel

I suppose-- one thing,, my old eyes are not that good anymore,, measure the distance in mm (plate lenght) and if you would,,describe the getters,,round,,angled etc-- next,,you should get them tested,,appears to be a nice little stash you have there.congrats.

george daniel

nevermind on the getters--the AT7 may be a Mullard-if you really want to know more(i'm limited),,you could shoot Jim McShane an e-mail,he's pretty good with tubes,esp from HK equipment.

michaeljhsda2

george daniel wrote: »

I suppose-- one thing,, my old eyes are not that good anymore,, measure the distance in mm (plate lenght) and if you would,,describe the getters,,round,,angled etc-- next,,you should get them tested,,appears to be a nice little stash you have there.congrats.

Thanks. Yes I was quite surprised to see these types of tubes in there. I'll get in touch with him. Thanks for taking the time to help me out.

heiney9

The mC1 are long plate versions of 12AX7's. "D" is Hamburg made and 7 is 1957. Very desirable tubes if they test very good. I have the short plate version of the same 12AX7 and I paid a lot for a used pair..........more than I'm usually willing to pay.

When I have more time to be on-line I can help more, but now I have to go.

H9

michaeljhsda2

Thanks for the info H9. One of the tubes has about 54 years of dirt on it and I dare not try to clean it off. The other tube is cleaner because it was inside an individual tube housing. The receiver worked at the time I bought it, however, I really need to invest in a tube tester.

michaeljhsda2

Made in Hamburg, Germany...very interesting...I thought that since the label said that they were made in Holland, the mC1 source code would not apply to these tubes. However, now that I think about it, I also have a quad of these 12AX7/ECC83 Siemens & Halske "Made in Germany" with date/source codes of mC5 from 1958 which are long plates as well. Sounds like tube companies outsourced their manufacturing to other countries...is that what they did? I need to get my read on.

george daniel

yes--Brock is more "learned" than I,, but thats why the codes are important,, not necessarily the "label". Ex; I have some 6SN7's,, that are labeled "Baldwin",, but they are Sylvania's,, as represented by the manuf. code.Hope this helps.

michaeljhsda2

Yes that does help. I'm finding out that there all kinds of exceptions, variables, etc. when it comes to tubes. Although you can't see it in the pic, the 12AT7/ECC81 is a GE tube but it was made in England (you mentioned possibly by Mullard?)

heiney9

The only thing that matters on tubes is the codes. The 12AT7 says made in Great Britain but the 188-5 code is a GE code.

Philips was a huge tube conglomerate that owned several tube factories, and yes there was a huge amount of cross branding depending on production supply and demand. Remember these tubes weren't used for audio and no one was critically listening to them in audiophile gear back then.

Now we listen for differences between manufacturing plants as they all sound a little different. Back then they needed to meet demand in any way possible. Even Telefunkens in the later days could be from other manufacturer's. A true Telefunken signal tube always has the diamond in the bottom between the pins.

H9

headrott

I believe you may have some "rebranded" 12AX7 tubes. The 12AX7's are obviously not "made in Holland" as stated on them. Amperex Bugle Boys were not made with the 45 degree halo getters either, I am almost certain. As Brock (H9) said, they were made in Hamburg, Germany as proven by the date codes on the bottom of the tube and the 45 degree halo getters (assuming the date codes are real).

I would guess originally the tubes were originally branded as Valvo's, possibly. I believe there were a few other companies that had 45 degree halo getters, but I don't remember which ones off the top of my head. I may be completely off my rocker about the rebranding, but I am fairly certain of it by the tube structure and labeling of the tube.

Greg

michaeljhsda2

When I was looking at the pics in the ad before I bought the receiver, I could see a couple tubes that said "Made in Holland" so I figured what they heck, there might be some good 12AX7's in there. I'm pretty confident the person who sold me the receiver had no idea that they were in there, otherwise they would have pulled them. Very interesting info guys, thanks.

heiney9

Regardless if were they Bugle Boys or Valvo Hamburg (which they definitely are, no question) both are very nice sounding tubes. I missed that they were 45* getters, but that is definitely a Valvo trait.

Like I said a tube can have any brand or info silk screened on it, it's the manufacturing code that tells all, as well as being able to identify tube structure (not always easy in photos). Depending on demand manufacturer's bought tubes from each other and put their own brand on it all the time. There are alot of private branded Telefunkens out there. One thing to note is that if you find, for example, an Edicron labeled tube, they are known to be manufactured by Telefunken, but that doesn't mean every tube Edicron put it's label on was a Telefunken, you have to know what you're buying because a lot of the private brands used tubes from all manufacturer's depending on supply and demand. Most Baldwin and Wurlitzer organ tubes were sourced from American tube companies, but not always. Predominately Baldwin tubes were either Raytheon or Sylvania manufactured tubes, but again not always............you have to check the codes and then try to identify by the internal structure to know for sure.


The two types of signal tubes I've read about being faked more than any others, 1) Telefunkens 2) Amperex Bugle Boys. I can't quickly find my link, but there is a way to tell. AFAICT, no one has faked the tube codes. Only the very early tubes had the codes on the bottom of the tube between the PIN (Philips tubes that is). The rest were acid etched on the side towards the bottom (Again talking about Philips tubes).

H9

michaeljhsda2

heiney9 wrote: »

Regardless if were they Bugle Boys or Valvo Hamburg (which they definitely are, no question) both are very nice sounding tubes. I missed that they were 45* getters, but that is definitely a Valvo trait.

Like I said a tube can have any brand or info silk screened on it, it's the manufacturing code that tells all, as well as being able to identify tube structure (not always easy in photos). Depending on demand manufacturer's bought tubes from each other and put their own brand on it all the time. There are alot of private branded Telefunkens out there. One thing to note is that if you find, for example, an Edicron labeled tube, they are known to be manufactured by Telefunken, but that doesn't mean every tube Edicron put it's label on was a Telefunken, you have to know what you're buying because a lot of the private brands used tubes from all manufacturer's depending on supply and demand. Most Baldwin and Wurlitzer organ tubes were sourced from American tube companies, but not always. Predominately Baldwin tubes were either Raytheon or Sylvania manufactured tubes, but again not always............you have to check the codes and then try to identify by the internal structure to know for sure.


The two types of signal tubes I've read about being faked more than any others, 1) Telefunkens 2) Amperex Bugle Boys. I can't quickly find my link, but there is a way to tell. AFAICT, no one has faked the tube codes. Only the very early tubes had the codes on the bottom of the tube between the PIN (Philips tubes that is). The rest were acid etched on the side towards the bottom (Again talking about Philips tubes).

H9

Great info!

michaeljhsda2

heiney9 wrote: »

The only thing that matters on tubes is the codes. The 12AT7 says made in Great Britain but the 188-5 code is a GE code.

Philips was a huge tube conglomerate that owned several tube factories, and yes there was a huge amount of cross branding depending on production supply and demand. Remember these tubes weren't used for audio and no one was critically listening to them in audiophile gear back then.

Now we listen for differences between manufacturing plants as they all sound a little different. Back then they needed to meet demand in any way possible. Even Telefunkens in the later days could be from other manufacturer's. A true Telefunken signal tube always has the diamond in the bottom between the pins.

H9

Notice on the bottom of the tube that there is an "A" stamped there. According to the Brent Jesse website, this mark denotes that it is a very scarce Whyteleafe, England (Mullard?) factory mark which made select tubes only for the military. Could this mean that it's a Mullard tube that was relabeled GE?

heiney9

That is a strange one for sure......all kinds of inconsistencies with tubes. I'd have to see a detail of the internal structure to know for sure at this point.

H9

michaeljhsda2

heiney9 wrote: »

That is a strange one for sure......all kinds of inconsistencies with tubes. I'd have to see a detail of the internal structure to know for sure at this point.

H9

Some close ups

heiney9

What are the etched tube codes? I see Tk1....something towards the bottom. Box type plate with 3 side holes is definitely a Mullard trait. Most if not all American made 12AT7's have the wing type plates.

It appears at this time to be a Mullard made tube that was relabeled by GE. I have a pair of 6AQ8's (ECC85) that have the exact same type of markings.

Please give me the etched tube codes on the side.

michaeljhsda2

Looks like Tk3 B6D3

michaeljhsda2

I just tested the 12AX7's Bugle Boy's (Valvo's) and they test strong on my Eico 667.

heiney9

Tk3
B6D3

Most likely not the rare Mullard Brent Jesse speaks of.

Tk3 is a pretty late revision

B = Blackburn
1966.

Should be a real solid Mullard tube with all the wonderful traits Mullards are known for. It is a somewhat rare tube in that is had has 3 side holes in the plates, but to be honest most of my Mullard small signal tubes have 3 holes in the plates, not all but many.

H9

michaeljhsda2

Thanks for the translation H9. It also tests strong along with the rest of the tubes.