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Valve info

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On 17/02/2020 at 22:43, Monitor Gold Ten said:

Good evening all! After a particularly "Challenging" journey back from work, I decided to work out Mullard Codes. 

My findings are as follows: B7J5; Blackburn, '57/'67/'77, Week 5 October.

How can I tell the decade? 

This is how I've chosen to relax. With Wes Montgomery in the background... 👍 👍 👍 😎 😎 😎 

Reputable sources say that weekly codes on Mullards weren’t introduced until 1961 and not on all valves. It was another couple of years before every valve had that ID. So , It’s likely that your Mullard is ‘67,possibly’77. 
You  can mebbe narrow it down further. Think I have a few lists somewhere, ah’ll have a look.

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On 19/02/2020 at 01:54, locheeboy said:

Reputable sources say that weekly codes on Mullards weren’t introduced until 1961 and not on all valves. It was another couple of years before every valve had that ID. So , It’s likely that your Mullard is ‘67,possibly’77. 
You  can mebbe narrow it down further. Think I have a few lists somewhere, ah’ll have a look.

Early 1960s for some, but some were earlier and some later. As above, you can aften tell by the getter type, but on some there is effectively no difference between a 1967 and 1977. Still, they'll beat most newer stuff anyway, and certainly the 'Mullard' reissues.

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If the valve in question has  the old style  'shield'  logo and a four character code  then it dates from 1967.  Around  1969 / 1970  a  more modern looking , less detailed  / trendy style of logo was introduced.  If the valve displays the later shield print along with a 4 character code , then it was manufactured in 1977. 

Edited by TECUMSEH VALLEY
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Could be old wine in new bottles, I have many new print Mullard toobs that appear to be old production, later labelled.
Of course the opposite doesn't happen except with fakes

Sent from my BLA-L09 using Tapatalk

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I found this site useful when starting out on my Valve Journey. I'm absolutely confident all my Mullards are genuine. 👍😎

https://www.effectrode.com/knowledge-base/mullard-ecc83-12ax7-reissue-vs-original-a-physical-comparison/

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Hi all...

And especially sir Rabski :D

Iam in a conundrum now . I just got a pair of 300B set power amps. And also have a pair of kt88 power amps ( can also accommodate EL34's )

now my conundrum is which to use for the mid range and which for the treble. Ian aware that the best way is for me try it out myself. However, if I need the 300B's for the mid range alone, then the previous owner is willing to modify them to increase the power out out to 9 watts, from the present 6W. And if I use them for treble duties only, then 6W will be enough.

Thus, can someone suggest from their listening experience if 300B SET sounds best for mid range or treble duties. 

Iam aware that this is a very funny query. But had to get it off my mind...so please bear with me :D

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Impossible to answer, because as always, it's the circuit and amplifier, not the specific valves. Overall, however, the obvious answer is 'both', so try it and see. Personally, I'd expect a single-ended to have a more 'lucid' presentation than a push-pull, so possibly better for mids. Only your ears can tell you.

Not entirely sure how it could be modified to increase the output and I'd be wary of that suggestion, as it would mean changing the operating point and probably increasing distortion and non-linearity. You can get more power out of any valve amplifier, but doing so with 'small' modifications is usually not ideal. The original designer would have chosen the operating point of the valves for a number of reasons, but without the schematics and knowing all the components (especially the output transformers) it's all guesswork.

The simple answer is to experiment with the setup without modifying anything. The output may prove enough for the mids anyway.

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49 minutes ago, rabski said:

Impossible to answer, because as always, it's the circuit and amplifier, not the specific valves. Overall, however, the obvious answer is 'both', so try it and see. Personally, I'd expect a single-ended to have a more 'lucid' presentation than a push-pull, so possibly better for mids. Only your ears can tell you.

Not entirely sure how it could be modified to increase the output and I'd be wary of that suggestion, as it would mean changing the operating point and probably increasing distortion and non-linearity. You can get more power out of any valve amplifier, but doing so with 'small' modifications is usually not ideal. The original designer would have chosen the operating point of the valves for a number of reasons, but without the schematics and knowing all the components (especially the output transformers) it's all guesswork.

The simple answer is to experiment with the setup without modifying anything. The output may prove enough for the mids anyway.

Thanks a ton sir :)

Will stick to the amps in the 6 watts configuration as advised. And will try with mids to start with and see. I just can't wait to back home from my sail. As you may understand Iam very very excited to try My first ever SET amps . Almost a kid in the candy store right now :D

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Super Wammer
Posted (edited)

Just had these 2 pairs of little NOS beauties delivered.

1951 Sylvania 6SN7GT (Bad Boy)

1945 Sylvania JAN CHS 6SL7GT

Thought I would give my MB845SEs a  treat, hopefully they will sound good. 

15832351287873893709167412207517.jpg

1583235624298359964644195340211.jpg

Edited by Lurch
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