Ratbob Posted September 25, 2022 Posted September 25, 2022 They are all 12BH7 but I can’t recall the make. One still has a bit of the manufacturer’s label and the number 265. Are they of any value? Thanks in advance, Cheers.
muon* Posted September 25, 2022 Posted September 25, 2022 The left one looks like the Mullard shield logo. Kirk will sort it out
Ratbob Posted September 25, 2022 Author Posted September 25, 2022 8 minutes ago, muon* said: The left one looks like the Mullard shield logo. Kirk will sort it out Thank you. That’s it, wow, and you’ve jogged my memory. It’s come back now in a flood of embarrassment. I got them from Graeme Cohen great guy. He said they were all the same. I think his company was Valve Research. Met him when I was invited to hear his premier amp at a customers house in North Adelaide driving some Duntech Sovereigns. Quite amazing. I look forward to hearing from Kirk. Cheers
muon* Posted September 25, 2022 Posted September 25, 2022 (edited) They may all be Mullards, but Kirk will be able to tell you the versions they are. They appear to have different plates one being shiny black @xlr8or Edited September 25, 2022 by muon*
xlr8or Posted September 25, 2022 Posted September 25, 2022 (edited) The 2 grey plates on the right were made in AU in the AWV factory in the 1960's. I'm pretty sure they were made by Philips in the Hendon factory in Adelaide. The black shiny plate on the left looks likes a Brimar UK tube made in the late 1950's. Can you see any number-letter-number/number-number-number-number code on it? Ignore the '265' code as it's not relevant. Edited September 25, 2022 by xlr8or 1 1
Ratbob Posted September 25, 2022 Author Posted September 25, 2022 Thank you Photos are a bit tricky, hope the attached clarifies. All played appear the same. I also found some old pics of Graeme and his creations, I wonder what he’s up to these days. Hope the extra pic helps. 1
Guest crankit Posted September 25, 2022 Posted September 25, 2022 25 minutes ago, Ratbob said: Thank you Photos are a bit tricky, hope the attached clarifies. All played appear the same. I also found some old pics of Graeme and his creations, I wonder what he’s up to these days. Hope the extra pic helps. Those amps
Ratbob Posted September 25, 2022 Author Posted September 25, 2022 10 minutes ago, crankit said: Those amps Oh yeah, I agree. Two of the mono blocks as shown in the bottom pic was $10k at the time, late 80s.
muon* Posted September 25, 2022 Posted September 25, 2022 Bubble wrap removes some print from tubes, best to store with something else. 1
Ratbob Posted September 26, 2022 Author Posted September 26, 2022 15 hours ago, xlr8or said: The 2 grey plates on the right were made in AU in the AWV factory in the 1960's. I'm pretty sure they were made by Philips in the Hendon factory in Adelaide. The black shiny plate on the left looks likes a Brimar UK tube made in the late 1950's. Can you see any number-letter-number/number-number-number-number code on it? Ignore the '265' code as it's not relevant. Hi Kirk Sorry for the delay I needed to get a mini led torch to shine across the glass. The tube with the remnant of a shield emblem has, about level with the bottom plate what looks like an R above what might be a 7 (not clear) In the same locations and quite clearly one tube has RM above 15 the other has VC above 31 all quite small print. All share the same boxed image 12BH7. Thanks for your expertise.
xlr8or Posted September 27, 2022 Posted September 27, 2022 From the manufacturing codes that have been provided it appears all 3 tubes were made in the AWV factory in Ashfield. In terms of tonal characteristics they would be ranked in the middle of the top 10 12BH7 tubes to own. For the RM 15 coded tube its manufacturing date was 15/12/66. For the VC 31 coded tube its manufacturing date was 31/03/70. Can you share a close up photo of the R 7 code to help decipher it further? Also, does this tube have black shiny anode plates or grey anode plates. The 2 photos of the 3 tubes taken suggests that the far left tube is not the same one in both photos. 1
Ratbob Posted September 28, 2022 Author Posted September 28, 2022 8 hours ago, xlr8or said: Can you share a close up photo of the R 7 code to help decipher it further? Also, does this tube have black shiny anode plates or grey anode plates. The 2 photos of the 3 tubes taken suggests that the far left tube is not the same one in both photos. Thank you for the information. Please see attached pics and sorry for the typo, the code is RM above a 7? When shining a light into the tubes they all have the same colour as shown here. Yes, we’ll spotted the tube positions were different, the left tube with the logo was subsequently on the right, all pics provided in this post are of that tube. (devils to photograph)
xlr8or Posted September 28, 2022 Posted September 28, 2022 (edited) RM 7 represents 07/12/66 production. You can use the other RM 31 coded tube as a matched pair for manufacturing date if both tubes test the same for NOS. Edited September 28, 2022 by xlr8or 1 1
Ratbob Posted September 28, 2022 Author Posted September 28, 2022 12 minutes ago, xlr8or said: RM 7 represents 07/12/66 production. You can use the other RM 31 coded tube as a matched pair for manufacturing date if both tubes test the same for NOS. Thank you for sharing you expertise, it’s appreciated. Cheers.
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