Personally I wasn't fond of tiny tubes like the 12a*7 .... until I started using Elekit TU-8200 and also when I audition the Auris Nirvana.
12at7 gain is 60. 6SL7 is 70. 12au7 & 6sn7 & EL11 are 20. 12ax7 is 100. Odyssey will be very versatile with all these drivers... not to mention the countless power tubes usable.
Personally I wasn't fond of tiny tubes like the 12a*7 .... until I started using Elekit TU-8200 and also when I audition the Auris Nirvana.
12at7 gain is 60. 6SL7 is 70. 12au7 & 6sn7 & EL11 are 20. 12ax7 is 100. Odyssey will be very versatile with all these drivers... not to mention the countless power tubes usable.
Personally I wasn't fond of tiny tubes like the 12a*7 .... until I started using Elekit TU-8200 and also when I audition the Auris Nirvana.
12at7 gain is 60. 6SL7 is 70. 12au7 & 6sn7 & EL11 are 20. 12ax7 is 100. Odyssey will be very versatile with all these drivers... not to mention the countless power tubes usable.
One thing you need to watch out for with these high gain tubes is high-frequency rolloff. Most high gain tubes have very high plate resistance, which forms a low-pass filter with the input capacitance of the output stage. Depending on the plate resistance and the input capacitance, the HF rolloff can creep down into the audio band. All design dependent of course, if using a hybrid mu-follower driver ( which has low output impedance) or the input tube is working into a buffer (which has low input capacitance), like in an OTL output, it isn't a problem.
It's for this particular reason the 300B is described as "hard-to-drive". Not only does the input tube need to have sufficient gain to swing a lot of voltage to drive a 300B to clipping, but it's input capacitance is relatively high due to the Miller effect - thus, the driver stage needs to have a low output impedance as well to avoid the HF rolloff issue. So, if you use an input tube with a gain of 100 in an amp it wasn't designed for and find the highs aren't quite so sparkly, that might be why.
You know, I bought some tubes from Bangy Bang recently, first time, but he had what I needed. The end result as as you would expect - he did not combine shipping despite my pointing out that eBay wasn't doing it automatically, as he claimed. One tube out of four was a dud, I contacted him about a return and never got a response, just went through eBay and returned both pairs, never again!
One thing you need to watch out for with these high gain tubes is high-frequency rolloff. Most high gain tubes have very high plate resistance, which forms a low-pass filter with the input capacitance of the output stage. Depending on the plate resistance and the input capacitance, the HF rolloff can creep down into the audio band. All design dependent of course, if using a hybrid mu-follower driver ( which has low output impedance) or the input tube is working into a buffer (which has low input capacitance), like in an OTL output, it isn't a problem.
It's for this particular reason the 300B is described as "hard-to-drive". Not only does the input tube need to have sufficient gain to swing a lot of voltage to drive a 300B to clipping, but it's input capacitance is relatively high due to the Miller effect - thus, the driver stage needs to have a low output impedance as well to avoid the HF rolloff issue. So, if you use an input tube with a gain of 100 in an amp it wasn't designed for and find the highs aren't quite so sparkly, that might be why.
Good to know. Thanks! Never paid much attention to that, but now that you point it out a 12AT7 has more than twice the plate resistance of a 6SN7 (15,000 versus 6,700 at 90 - 100v on the plates). I want to try the Brimar in an OTL (the Incubus), but don't have a clue how the circuit is set up.
You know, I bought some tubes from Bangy Bang recently, first time, but he had what I needed. The end result as as you would expect - he did not combine shipping despite my pointing out that eBay wasn't doing it automatically, as he claimed. One tube out of four was a dud, I contacted him about a return and never got a response, just went through eBay and returned both pairs, never again!
One thing you need to watch out for with these high gain tubes is high-frequency rolloff. Most high gain tubes have very high plate resistance, which forms a low-pass filter with the input capacitance of the output stage. Depending on the plate resistance and the input capacitance, the HF rolloff can creep down into the audio band. All design dependent of course, if using a hybrid mu-follower driver ( which has low output impedance) or the input tube is working into a buffer (which has low input capacitance), like in an OTL output, it isn't a problem.
It's for this particular reason the 300B is described as "hard-to-drive". Not only does the input tube need to have sufficient gain to swing a lot of voltage to drive a 300B to clipping, but it's input capacitance is relatively high due to the Miller effect - thus, the driver stage needs to have a low output impedance as well to avoid the HF rolloff issue. So, if you use an input tube with a gain of 100 in an amp it wasn't designed for and find the highs aren't quite so sparkly, that might be why.
Thanks. It's fascinating to read technical stuff. I'm a software guy but I read tech stuff out of interest. Basically in the world of audio, I'm a consumer. I consume.
I do know that Tomas build Odyssey around the driver choice of either EL11 or 6SL7. Both different gain and how he accomplish that with auto bias is something I wouldn't know. I will just wait to see and hear. The original design was to consider 6SL7 and 6SN7 in that same socket. For some strange reason I wanted the alternate driver to be 6J5 / L63 but Tomas knew that I have some NOS EL11 and persuaded me to use it. That revive my Berlin love - to use the Telefunken combination of EL11 and EL12 spez. Of course now that I have EL39, I would want to pair that with EL11 also. Really curious how that will turn out. I had barely use my Tung Sol 6550 with Eric's amp when I had to return the amp. I remember being very impressed with the 1960s Tung Sol 6550. Then there's the Radiotron 807. An incredible sounding power tube imo. Not forgetting the tube that Odyssey is bias for, the KT88. Tomas told me recently that he will not run KT88 to optimum, so that the amp will be cooler and more importantly, will be able to roll in more power tubes. Which brings me to EL34. The tube in Auris Nirvana that wow me and started me on this path to get a custom amp. There's also KT66 and KT77 and 6L6GC.
Odyssey will be special for me because the tube variations is a lot. I even have to scale it back to keep it simple stupid. I didn't want to spend all my time fiddling with tube changes and manually adjusting bias settings. I did that on McChanson's KT150 amp. Initially it was interesting because I have something to fiddle with but eventually the novelty wore off. All I wanted to do was listen to music and be impressed tonally at how the tube amp drives my headphones. I know that at the end of the day that's what I want to do.
I mean look at my Wa22. I have all the good power tubes for it and some drivers. I hardly change tubes on it anymore. The other day I realised that after spending so much time with my LCD4 and Destiny (300b amp), I find my He1000se a bit bright. This is strange because I have not felt this way with He1000se before. Just goes to show that our brains and ears adapt to something after you live with it for a while. In this case, I live and love the LCD4 and 300b amp warm and cosy combination so much that when I return to He1000se, I find the latter too bright. That is when I know instinctively what tubes to use in the Wa22 to make it warmer. I chose Ken Rad 6sn7gt black glass, Bendix 6080wb and Cossor 53ku rectifier. See, knowing your tubes tone helps because you know what combination to use straight away. In time to come, I will know the tubes in Odyssey so well that it will be second nature just like it is with Wa22 now.
5:26am omg... I wrote that much ? Well in a few hours time I'll be journeying back to Canberra and will spend 5 weeks there. So much to do there to take my mind off head-fi but I know that I will think of Odyssey. I remember Family Man. I choose us.
That inspiration came from you. Tomas just mount it on top of the chassis and showed me if I like it there or in front. I said yeah that looks good....
This might seem trivial but having a badge with a name of my choice.... that's what I call custom. I mean can you imagine having a badge that says BcowenBang ?
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