Ha ha. We are both a super hero because we are different.
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Tube rolling thread | UltraSonic Studios
- Thread starter OctavianH
- Start date
I got a crazy idea this morning and I will reuse this spam post to write it. I was looking at AL3 which is a very interesting tube to try. But the problem is that it has 4V heaters. Now, usually people use external power for different heaters but can we do something to drop 6.3V -> 4V in some simple circuitry and avouid external power supply?
DELETED. Does not work as simple as thought, but with some voltage regulator inside some adapters might work.
DELETED. Does not work as simple as thought, but with some voltage regulator inside some adapters might work.
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Isaacc7
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George aka Tubelab over in DIYaudio made a pretty nice spreadsheet with a breakdown of tubes with similar pinouts. Not exhaustive but can be a useful resource.
https://www.diyaudio.com/community/attachments/masterchart_3-18-24-xlsm.1292321/
https://www.diyaudio.com/community/attachments/masterchart_3-18-24-xlsm.1292321/
Very useful, thanks for sharing. When I started to write pinouts in my notes I was not smart enough to use each pin as columns. I went for rows and now it's not that easy to filter and search for compatible pinouts of different tube types. This link is done properly.
My mind remained since yesterday at the Telefunken ED8000 but it seems I cannot bias it, or it might be at the very limit. As far as I see, for 200V/20mA I would need a grid bias around -56V. Nope, this one cannot work in my amp. I was able to go around -54V maximum.
But I could buy another amplifier for this. LOL
But I could buy another amplifier for this. LOL
These GEC A2293 evolved a lot in the last 2 days. While they got an idea more dynamic, they also got softer. This is how GEC tubes age. For specific genres this is the perfect sound. In my case I like the sound to be an idea crisper and more raw. Anyway, good tubes.
By the way @LobalWarming please help me understand more from this curve tracer screenshot. You said that the specs are better related to output impedance. Hmm, I guess you are referring to the low right section where you have rp? I am an ignorrant and for me almost all triode graphs are the same, help me understand how based on a datasheet or measurements I can determine that a tube will perform better than other on my amp, if that's possible.The specs of A2293/CV4079 are better than a single section of most any 6080/6AS7 in terms of output impedance.
LobalWarming
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Yes, lower rp, as compared to 6AS7 and most 6080s. Important value for an OTL. For a traffo-connected amp, not that critical, ime.
If I only knew this at the times I was using OTL amps. LOL
Isaacc7
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Current setup:
The 6005 as drivers are giving me a full, rounded sound. Pictured are the CSF 6005 driving Sylvania 6bg6ga. Will switch over to ultra linear tonight to see what impact that has.
The 6005 as drivers are giving me a full, rounded sound. Pictured are the CSF 6005 driving Sylvania 6bg6ga. Will switch over to ultra linear tonight to see what impact that has.
Your amplifier is very beautiful, I think you should post more often photos with it. A quad of EL90 on their own adapters on top of a double 6V6->6SN7 adapter. Nice.
Isaacc7
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The el90 as drivers experiment has been shelved for the time being. Switching to ultralinear had a dramatic effect on the sound. Much, much clearer and transparent. The bass had disappeared though. I have switched to an input tube that I thought would complement the new sound and I was right. The KTZ41 gives me plenty of bass but it also opened things up considerably. Running the Sylvania 6bg6ga in triode sounds downright tubby in comparison.
These particular 6bg6ga actually have the same guts as a 7027a which can take quite a bit more voltage than the original version could. Looking for operating points of a 6l6gc in ultralinear I came across this page https://www.cascadetubes.com/optimization-of-the-6l6-se-ul/ According to him, regardless of the voltage chosen distortion is so low that it really isn’t a deciding factor when it comes to what settings to use. Since he was testing single ended use that goes doubly for me. Push pull will yield even lower distortion. So I will eventually crank these up to 400v and see what I get out of them.
These particular 6bg6ga actually have the same guts as a 7027a which can take quite a bit more voltage than the original version could. Looking for operating points of a 6l6gc in ultralinear I came across this page https://www.cascadetubes.com/optimization-of-the-6l6-se-ul/ According to him, regardless of the voltage chosen distortion is so low that it really isn’t a deciding factor when it comes to what settings to use. Since he was testing single ended use that goes doubly for me. Push pull will yield even lower distortion. So I will eventually crank these up to 400v and see what I get out of them.
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I waited a few days listening to A2293 in output section. But it is time for us to move on, of course, everyone in its direction. In my case I was lucky to be able to find a pair of RT 4654 Mesh Anode. This one looks more like the "classic" EL39 made in France which all praise and my expectation is that these have the RT house sound and not the Philips one. I think these are forefathers of the classic octal EL39 and are under the performance of the older Philips models. But of course, this is at the moment only an assumption. These tubes were listed in an auction which had 1 bidder, me. They are not new but in very good condition, but needed some cleanup (still need) and need also to be left in operation on the tester to be sure I am able to make correct measurements. From what I see now in the first minutes, they are close or even above 100%.
Let me show you more:
Mesh anode:
Since I bought these not tested and they looked as being stored for many years, I treat them with caution. So I will not put these on the amplifier unless they will pass some tests. However, only looking to them is rewarding, a very beautiful tube. Let's see later if indeed my assumptions related to sound are right.
Let me show you more:
Mesh anode:
Since I bought these not tested and they looked as being stored for many years, I treat them with caution. So I will not put these on the amplifier unless they will pass some tests. However, only looking to them is rewarding, a very beautiful tube. Let's see later if indeed my assumptions related to sound are right.
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And here we are, after 30-45 minutes of different checks and cleanup and so on, checking assumptions we previously made about RT 4654 Mesh Anode. And I was right, these have the RT sound, darker and more forgiving. These are 4654 but not the Philips 4654. Now we can speak about Philips sound and non Philips sound on a 4654 (Tesla or RT). I expect these are very close sounding to RT EL39. At this point RT started to manufacture their own tubes and applied their own sound to 4654. My other "red base" versions do not sound like this (remember EBL1 I have with RT logo?).
It is definitely a good sound, but not at the level of my top tier tubes. However, enjoying them. I will spend more time with these but from my point of view, things are clear and this is why I bought these, to understand how to identify and find the Philips sound. When it starts and where it ends? Are Philips 4654 some EL39? Well, electrically might be, but it is not enough. Philips old sound is more than a tube type and I have proven this when comparing RT EL41 and Philips EL41 Sittard. Now, I face the same situation here with RT 4654 vs Philips 4654. Same tube type, many would say same tube, for me 2 different house sounds.
It is definitely a good sound, but not at the level of my top tier tubes. However, enjoying them. I will spend more time with these but from my point of view, things are clear and this is why I bought these, to understand how to identify and find the Philips sound. When it starts and where it ends? Are Philips 4654 some EL39? Well, electrically might be, but it is not enough. Philips old sound is more than a tube type and I have proven this when comparing RT EL41 and Philips EL41 Sittard. Now, I face the same situation here with RT 4654 vs Philips 4654. Same tube type, many would say same tube, for me 2 different house sounds.
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Time for a new experiment: EL30. This is a tube I was not able to find more information about. It seems it was produced by Philips France and usually found with metal base branded RT or black base (maybe also metal?) like some Visseaux tube. But if you look about this tube, well, almost nowhere nothing. This raised a flag in my mind: I'll have to try it but first check it to see if it behaves normally on the tester. Lack of info is a risk.
So here we have a quad of these:
A detailed photo:
And then some measurements. Being bought quite cheap, I had no expectation and because I was not able to find any info about it also my willing to spend was limited. But I found a quad for 20 EUR and then my curiosity led me to buy these. Now, from the 4 pieces one is DOA (even if it heats, no light is seen on the heater and emission is 0 so I presume it's dead). Then measurements are quite ok for the rest, measured as I found on Radiomuseum (Va=250V, Vg2=250V, Vg1=-4.5V and Ik=18mA), so 86%, 89% and 104%. Decent values. From the 3 pieces which work, I have selected the ones being closer and made a pair. On the amp these are around -5.2V grid for 180V/4mA.
Now soundwise, well these sound an idea dull at 4mA and most probably they sound better at around 18mA as advertised but well, here's a funny thing. I have to put these at 18-20mA and 200V in the output for around -2.5V and my negative grid bias there does not go so "up", at minimum I have around -3.5V. LOL So I cannot test these in output, what a shame.
In short, I'm forced to try these only on input on top of some 6V6 -> 6J5 adapters (pinout is the same as 6V6). Regarding the specs, Radiomuseum speaks about 4.5W but on some sites I've seen totally different values. For example our "specially made for audiophiles" website Vint'Elec speaks about 25W here but I doubt they are right. I think Radiomuseum has the right specs for these.
Now, I have to admit I do not like these on top of RT 4654, I tried them before with Philips 4689 and was no good pairing either. Sound an idea dull, lack sharpness and separation and make everything somehow unexciting. A tube nobody heard about which does not impress me. It was fun to try on output but well, I never thought I'll try a tube at -2.5V grid bias. So it's more in line with input tubes in my view at 4.5W. I doubt I'll listen to it too often but I will keep it around. One day it might shine.
That was EL30, moving forward.
So here we have a quad of these:
A detailed photo:
And then some measurements. Being bought quite cheap, I had no expectation and because I was not able to find any info about it also my willing to spend was limited. But I found a quad for 20 EUR and then my curiosity led me to buy these. Now, from the 4 pieces one is DOA (even if it heats, no light is seen on the heater and emission is 0 so I presume it's dead). Then measurements are quite ok for the rest, measured as I found on Radiomuseum (Va=250V, Vg2=250V, Vg1=-4.5V and Ik=18mA), so 86%, 89% and 104%. Decent values. From the 3 pieces which work, I have selected the ones being closer and made a pair. On the amp these are around -5.2V grid for 180V/4mA.
Now soundwise, well these sound an idea dull at 4mA and most probably they sound better at around 18mA as advertised but well, here's a funny thing. I have to put these at 18-20mA and 200V in the output for around -2.5V and my negative grid bias there does not go so "up", at minimum I have around -3.5V. LOL So I cannot test these in output, what a shame.
In short, I'm forced to try these only on input on top of some 6V6 -> 6J5 adapters (pinout is the same as 6V6). Regarding the specs, Radiomuseum speaks about 4.5W but on some sites I've seen totally different values. For example our "specially made for audiophiles" website Vint'Elec speaks about 25W here but I doubt they are right. I think Radiomuseum has the right specs for these.
Now, I have to admit I do not like these on top of RT 4654, I tried them before with Philips 4689 and was no good pairing either. Sound an idea dull, lack sharpness and separation and make everything somehow unexciting. A tube nobody heard about which does not impress me. It was fun to try on output but well, I never thought I'll try a tube at -2.5V grid bias. So it's more in line with input tubes in my view at 4.5W. I doubt I'll listen to it too often but I will keep it around. One day it might shine.
That was EL30, moving forward.
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