[gibosi]

At least I was not too far off LOL. Which letters are used for the other two quarters and what do they correspond to?
Another OPUS scheme?

Yes, it's similar to the OPUS scheme.

The other two letters are T, representing Nov 1 through Feb 1, and N, respresenting Feb 1 through May 1. This scheme was used by Sylvania between 1939 and about 1947.

 

[mordy]

I have an Arcturus 6N7G that has the codes
N 4
R 4
on it. It is definitively a 30's to early 40's tube but I can't figure out the dates. Any suggestions?
This tube came out in 1936 and Arcturus went bankrupt in the early 40's. My guess is between 1936 - 1942.
The Arcturus name continued into the 60's but only as rebrander.

 

[gibosi]

I have an Arcturus 6N7G that has the codes
N 4
R 4
on it. It is definitively a 30's to early 40's tube but I can't figure out the dates. Any suggestions?
This tube came out in 1936 and Arcturus went bankrupt in the early 40's. My guess is between 1936 - 1942.
The Arcturus name continued into the 60's but only as rebrander.

Sorry, but I have no information on Arcturus date codes, so I can't help you. We know that the 6N7G was introduced in 1936 and Arcturus ceased operations in 1941. And until we can find the key to the date codes used by Arcturus, I think your guess is as close as we can get.

 

[mordy]

We have to do a little creative thinking....
N 4 = April 1940
R 4 = Rare, very
Sounds logical, no?

Can you weigh in on British pre-war or WW2 tubes? AMERTY means American Type. A M means Air Ministry. AnM means what? NAPL101 means what?

 

[gibosi]

We have to do a little creative thinking....
N 4 = April 1940
R 4 = Rare, very
Sounds logical, no?

Can you weigh in on British pre-war or WW2 tubes? AMERTY means American Type. A M means Air Ministry. AnM means what? NAPL101 means what?

I'm don't have any information about AnM and NAPL101. Sorry....

 

[Velozity]

I've got some better pictures comparing the 6J5G and 6J5GT construction. They look to be the same except for the top micas. I'll post these pics in the 6J5 thread as well.

 

[GDuss]

I've got some better pictures comparing the 6J5G and 6J5GT construction. They look to be the same except for the top micas. I'll post these pics in the 6J5 thread as well.

Nice family photos!!!

 

[Karnicopia]

Got in my Fivre Drivre's (6j5) today and I'm really enjoying these. I've started to try and reserve judgement until they get some hours on them because the Cetron's changed so much over time but honestly this pairing is doing something for me. The Fivre's add a bit of energy to the high end and it just balances really well with the Bendix and I guess the amp and the Verite. I had the GEC 6J5's in there for a while but I seem to really like these. Maybe that's just because they sound a bit different but we'll see I really like them so far. They kind of look like baby Bendix too which I'm digging.

Definitely start with cleaning the pins. I have a Bendix that started to be noisy and I found that I could eliminate the noise by jiggling the tube around in the socket and listen for a quiet position of the tube. Just use a thick towel or similar - these tubes get really hot!
I have avoided expensive cables etc but I did find better bass definition with an inexpensive (~$10) 14 gauge “hospital grade” power cord from Amazon.

Thanks I had some after your post about this I actually keep a towel under the table in case I do want to check out a noisy tube (or dust before a picture lol I did my best but the rest was getting too close to hot tubes). I did use the towel to slightly push down on the base ring of the noisy tube a bit when I was testing and that did make a difference and quiet it but it would start up again over time and I could never get it to stay so I wasn't sure if one of the pins could be slightly bent out which was stopping the tube from seating fully or if it may just need to be cleaned up. I didn't see anything obvious with a pin being bent but I think this would be slight so I'm just going to focus on cleaning them as a good starting point because I don't want to mess with bending Bendix unless I have to.

Glad to hear you noticed a difference with the hospital cord and those seem really reasonable so I figured why not and I think the one I picked up was around $10 and 14g as well. I've really avoided expensive cables too but I noticed a good improvement with the ace hardware cable and I think that was mainly just the shielding was better and it makes sense that these would need to get clean power to devices that are high precision. I do have pretty well shielded cables between the dac and amp and then I went with optical into my dac which also seemed to help.

I think these have all been good positive steps so far and then I am going to pick up a PI2AES as a source for my dac. These are really reasonably priced too and are basically just an audio board you can buy to attach to a raspberry PI with an enclosure to provide a variety of audio outputs and it seems like there is a selection of audio only OS for the PI which allow you to either stream to it or attach local storage or you could even have it with local storage and running off of battery power but I doubt I would ever take it that far I kind of like the flexibility of using local storage or streaming if needed and you can run separate power supplies for the audio board and the pi board so that is kind of cool to isolate them. You can put the whole kit together for around $250 so it's really reasonable compared to a lot of the streamers or audio sources and the flexibility seems really interesting to me. It will probably take a few weeks because there is a wait for the audio board but I'm excited to try it out and see how it goes.

 

[mordy]

Got in my Fivre Drivre's (6j5) today and I'm really enjoying these. I've started to try and reserve judgement until they get some hours on them because the Cetron's changed so much over time but honestly this pairing is doing something for me. The Fivre's add a bit of energy to the high end and it just balances really well with the Bendix and I guess the amp and the Verite. I had the GEC 6J5's in there for a while but I seem to really like these. Maybe that's just because they sound a bit different but we'll see I really like them so far. They kind of look like baby Bendix too which I'm digging.



Thanks I had some after your post about this I actually keep a towel under the table in case I do want to check out a noisy tube (or dust before a picture lol I did my best but the rest was getting too close to hot tubes). I did use the towel to slightly push down on the base ring of the noisy tube a bit when I was testing and that did make a difference and quiet it but it would start up again over time and I could never get it to stay so I wasn't sure if one of the pins could be slightly bent out which was stopping the tube from seating fully or if it may just need to be cleaned up. I didn't see anything obvious with a pin being bent but I think this would be slight so I'm just going to focus on cleaning them as a good starting point because I don't want to mess with bending Bendix unless I have to.

Glad to hear you noticed a difference with the hospital cord and those seem really reasonable so I figured why not and I think the one I picked up was around $10 and 14g as well. I've really avoided expensive cables too but I noticed a good improvement with the ace hardware cable and I think that was mainly just the shielding was better and it makes sense that these would need to get clean power to devices that are high precision. I do have pretty well shielded cables between the dac and amp and then I went with optical into my dac which also seemed to help.

I think these have all been good positive steps so far and then I am going to pick up a PI2AES as a source for my dac. These are really reasonably priced too and are basically just an audio board you can buy to attach to a raspberry PI with an enclosure to provide a variety of audio outputs and it seems like there is a selection of audio only OS for the PI which allow you to either stream to it or attach local storage or you could even have it with local storage and running off of battery power but I doubt I would ever take it that far I kind of like the flexibility of using local storage or streaming if needed and you can run separate power supplies for the audio board and the pi board so that is kind of cool to isolate them. You can put the whole kit together for around $250 so it's really reasonable compared to a lot of the streamers or audio sources and the flexibility seems really interesting to me. It will probably take a few weeks because there is a wait for the audio board but I'm excited to try it out and see how it goes.

You could try to switch the positions of the Bendix tubes.
What worked best for me was to tilt the tube at a slight angle. It may look a little funny that the tube is not sitting straight in the socket but I solved that by not looking at the tubes lol.

 

[chrisdrop]

You could try to switch the positions of the Bendix tubes.
What worked best for me was to tilt the tube at a slight angle. It may look a little funny that the tube is not sitting straight in the socket but I solved that by not looking at the tubes lol.

Sometimes I get noise in one of my Bendix tubes. Resting a paperback book on top for a little while usually silences it.

 

[Karnicopia]

You could try to switch the positions of the Bendix tubes.
What worked best for me was to tilt the tube at a slight angle. It may look a little funny that the tube is not sitting straight in the socket but I solved that by not looking at the tubes lol.

Sometimes I get noise in one of my Bendix tubes. Resting a paperback book on top for a little while usually silences it.

Thanks that is exactly what is happening it's like if I put slight downward pressure it goes silent but then it would come back after a bit so I may try different positions just to see if that helps or I may try out the book method too as that seems safer than messing with the base now that I know it needs that bit of downward pressure. I am going to try and clean the pins because I figure that is good practice but I think these ideas are where I'll go next if that doesn't work.

 

[chrisdrop]

Thanks that is exactly what is happening it's like if I put slight downward pressure it goes silent but then it would come back after a bit so I may try different positions just to see if that helps or I may try out the book method too as that seems safer than messing with the base now that I know it needs that bit of downward pressure. I am going to try and clean the pins because I figure that is good practice but I think these ideas are where I'll go next if that doesn't work.

For me, sometimes proximity to the power transformer exacerbates microphonic/noisy tubes more. You might put it on the other side of the amp?

I have done all the remediation steps ala "Tube Doctor @mordy" (clean pins, soldering iron heat up pins, self adhesive silicone tape, etc). I haven't sorted it however. It is, bearable and my book solution is sufficient, a minor annoyance at worst. I have 2 pairs of Bendix and there is 1 noisier tube in each pair. Also, the "dummy plug" in my XLR socket helps lower the noise floor. To check if that helps, if you have a 2nd pair of headphones, try to plug them into your 2nd headphone jack (you have 1 of each 1/4" and XLR presumably). This is @Zachik's trick and if you have slight noise, it might fade enough into the background with this hack.

 

[Zachik]

This is @Zachik's trick and if you have slight noise, it might fade enough into the background with this hack.

That was a great accidental discovery!!
Between that, and my GOTL tube compatibility table - I am very happy I can contribute back to this great Glenn fan club

 

[mordy]

Maybe a silly question: Why not combine the quiet tubes from each pair?

 

[Karnicopia]

For me, sometimes proximity to the power transformer exacerbates microphonic/noisy tubes more. You might put it on the other side of the amp?

I have done all the remediation steps ala "Tube Doctor @mordy" (clean pins, soldering iron heat up pins, self adhesive silicone tape, etc). I haven't sorted it however. It is, bearable and my book solution is sufficient, a minor annoyance at worst. I have 2 pairs of Bendix and there is 1 noisier tube in each pair. Also, the "dummy plug" in my XLR socket helps lower the noise floor. To check if that helps, if you have a 2nd pair of headphones, try to plug them into your 2nd headphone jack (you have 1 of each 1/4" and XLR presumably). This is @Zachik's trick and if you have slight noise, it might fade enough into the background with this hack.

I will try out the position in relation to the transformer that makes a lot of sense and I will also check out the headphone trick Zachik had suggested I would probably like to make a plug as well but I'll try it out with headphones first. Someone on the Verite thread was saying it's better to turn on a tube amp with a load attached but there is also advice to not have your headphone in when you turn on your amp. I think the consensus ended up being you wouldn't want your headphone plugged in when you power on but you also don't want to leave the amp running for long with nothing plugged in so you should plug in your headphone rather quickly. I have no idea how true any of this was and it probably depends on how the amp was designed I'm still learning a lot of this I just follow L0rdgwyn's advice to turn on the amp and then plug in my headphone which doesn't really contradict any of this. I think Zachik's resistive dummy plug kind of solves both problems in that you don't have a open circuit when you power up the amp but you also aren't risking your headphones. I'll try it out with two headphones and see how it goes.

Overall I never really had a matched pair of Bendix I had just picked up the Tung Sol 5998 GEC 6j5 so I didn't want to spend too much and I had picked up two single Bendix for relatively cheap separately and then I liked the sound so much I picked up a backup. Now I am running with the quiet pair and it's silent but I'd like to see if I can figure out how to get that third tube quiet if possible but if not I'll use it as a way to diagnose noise in the rest of my system it seems like it's been effective with this. Where it started it was quiet most of the time but the noise would randomly start up and was at the point it was annoying during music if it was a quiet part of the song. Just switching between different outlets seemed to help but this wasn't anything earth shattering but it did help so I think it was a good step and then switching to the more shielded power cord was really significant and basically knocked it down to the point where I would only hear it if nothing was playing and I'd wager Zachik's trick would knock it down to where I couldn't hear it or it would be so low it wouldn't really matter I'll try that out and see I'm interested to build one but I'll just check with headphones first. I should get the hospital power cord in soon also and I can see if that helps further but even if it just works similarly to the ace cord I'll be happy and I'm not expecting too big of a difference because the ace cable is really overbuilt but we'll see.