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Tube rolling thread | UltraSonic Studios
Mar 22, 2024 at 5:01 AM Post #3,436 of 3,655
hpamdr said:
Some tubes like 12E1 can also cause bouncing.
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Why 12E1? We had a longer discussion here that some tubes are made to be used only with auto-bias. If you look into the datasheet of EL3 for example:

1711098036847.png


In my case, I have observed that this remark comes usually on tubes with high mutual conductance. These tubes generate increase/decrease of the current at very small changes of the grid voltage. Is 12E1 in the same situation? What do you think about this "only auto bias" requirement? I use here without problems EL41/EL3/12E1.
 
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Mar 22, 2024 at 9:13 AM Post #3,437 of 3,655
hpamdr said:
If you have very bad cable with shortcut, this can cause the bias to bounce... Some tubes like 12E1 can also cause bouncing. But if Bias is swinging without any tube nor any input cable, this is likely you have capacitor ready to die...
I'm using very/building short RCA cable 30cm ~12ft with amphenol or neutrik plugs not too tight not too loose ! Also as said by @OctavianH the best is to use XLR also because the plug is better built and more robust. I have some Vovox sonorus cable on my main system and I'm very happy with it. They also have super long cables 3 - 5 m :wink:
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That’s the thing, the bed cable was connecting my DAC to the preamp. Preamp to amp is XLR, it’s the only connection the amp uses. And yeah, since they are the same cables used in studios you can get them any length you want.
 
Mar 22, 2024 at 9:15 AM Post #3,438 of 3,655
In my humble setup I use the Eichmann RCA Bullet Plug and that one could never work loose.
https://www.tnt-audio.com/clinica/piano6_1_e.html
Ultra expensive cable as you can see for yourself.

Forgot to say that I use the solid core cable after comparing them...so I have Piano1, good for tube amps. I previously used them for my loudspeaker tube amps.
 
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Mar 22, 2024 at 9:15 AM Post #3,439 of 3,655
OctavianH said:
If you ever find out why a loose cable influences your meters please let me know. By the way, to avoid such problems I use XLR connectors for headphone/interconnects even on SE amplifiers, I always want to have something like this.
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I will ask the tech when I tell him what the solution was. I don’t understand how the DAC to preamp cable made the meters jump around on the amp that was connected by XLR.
 
Mar 22, 2024 at 9:22 AM Post #3,440 of 3,655
triod750 said:
In my humble setup I use the Eichmann RCA Bullet Plug and that one could never work loose.
https://www.tnt-audio.com/clinica/piano6_1_e.html
Ultra expensive cable as you can see for yourself.
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I’m not a cable guy so have never worried about them before. I sprung for some RCA cables from Bluejeans. Well built, very solid connection. It’s like a two step process, push them on until you feel resistance and then push some more and they pop on.

I will be getting my first synthesizer in June and will be buying a bunch of cables to go with it. Mine, https://musonics.com/ uses 1/4” patch cables so I will again be buying studio cables. If I connect it to my main system it’ll be through an interface. Mine has 1/4” TRS outputs. Already have long 1/4” to XLR cables just in case:)
 
Mar 22, 2024 at 9:41 AM Post #3,441 of 3,655
I have been telling myself that I wasn’t going to be buying any more tubes. I mentioned here before how I fell off the wagon but it is actually worse than I thought. Yes, I bought new tubes. N78 and cv4062 were originally going to be used as output tubes. Looking at them I can’t really believe that they can take the voltages the data sheet says they can. They are just tiny tubes, the smallest I own. The data sheet says they can do 350v in triode. I dunno… I have a feeling I will mostly be using them as inputs. I also bought a bunch of Svetlana 6j7 tubes from the mid 60s. A little bird told me they sound really good. Lots of chatter about other Russian small signal tubes so at $3 a pop why not? Oh, and also bought the Ericsson 18aq5 on a whim so will try those as well.

All that is bad enough but I also got in some adapters that allow me to use a pair of triode 6v6 instead of a 6sn7. Truth be told I don’t have many 6v6 and I’m not all that impressed with them. What I do have are other tubes with the same pin out and a bunch of tubes and adapters that will fit into these adapters. Here’s the list of new input tubes to try I have come up with so far:

6v6
7c5
14c5
6f6 x2
6k6
6aq5/el90 x6
KT81
N78/cv4062

I am especially interested in the 6f6, kt81, and cv4062. The cv4062 in particular has piqued my interest after reading about how good they are as drivers. If the kt81 sounds as good as I think they will I will probably get another adapter to finally use my n34 tubes because why not? Lol lol lol <manic laughter> God, I’m such a tube hipster. Tomas enabled me. I’m pretty sure I’m the only person in the world to ever combine ktz41 tubes with GU50. Let alone potentially n34 inputs driving 18aq5. Why stop there? How about n43 driving cv4062 or 5b/254m?

I must be stopped! This amp is making me spiral out of control! I will be out of work for several months and I think I know what I’ll be obsessing over during that time. Again. Sigh. :)
 
Mar 22, 2024 at 10:47 AM Post #3,443 of 3,655
OctavianH said:
Nah, I think those are interesting. 6K6 is good here, on output. Never tried on input.
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I was not overly impressed with them as output tubes in my amp. I will try them as inputs eventually just because why not. I’m actually more interested in both the 6aq5/el90 and kt81 on the inputs as well as my new GEC tiny pentodes.
 
Mar 22, 2024 at 11:50 AM Post #3,445 of 3,655
Mar 22, 2024 at 1:42 PM Post #3,447 of 3,655
I returned here to a combo I liked in the past, Tesla 4654 with RCA 9002.

Tesla4654_RCA9002.jpg


I think these 9002 tubes I got by mistake saved my 6C4 adapters. I was bored about the british 6C4 I was listening in the past and put these adapters to storage. But RCA 9002 caught again my attention towards single triodes and pairs well with the sharper and neutral sounding Tesla. This combo looks like David and Goliath, the size difference being quite big, I wonder how these would look with some EL51 on the output position. Maybe I'll have to do this, since now I have some larger wire adapters which should fit properly the Philips EL51.

Another thing I observe is that I perceive an idea different these tubes since I've switched from USB to coax on TT2, via SRC.DX, and the sound got more sharp and extended. Not a lot, but I still feel USB is an idea more polite. Made today some 1:1 and I had the same impression I had a few weeks ago. All in all, coax is for me an improvement on source side and I am happy I made this change. Also the Supra Excalibur was a worthy upgrade. But these upgrades went more towards a clinical/analytical yet natural presentation and now Tesla 4654 seems to me more technical than in the past. I like it a lot, these becoming slowly one of my favourite "low tier" tubes.

Coming from Philips EL41 disc getter metal base, which are warmer and more musical, also more vivid and rich in tone, these compensate with dimension. 4654 sounds big, and even the more sterile Tesla is very dynamic and impresses. It will not touch the Philips red painted base ones, but it remains for me a very special tube, above many others.

PS. Looking at the Tesla 4654 datasheet, it's fascinating. Hand written with some manually drawn schematics:

1711129395548.png
 
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