M70AB2
Well-Known Member
Do you mean coupling capacitors?
Were they film or electrolytic?
Film - Coupling
Electrolytic - Filter
Nobsound E6 Preamp Uses Directly Heated Tubes
- Thread starter FlaCharlie
- Start date
Do you mean coupling capacitors?
Were they film or electrolytic?
Film - Coupling
Electrolytic - Filter
drjohnnyfeva
Well-Known Member
drjohnnyfeva
Well-Known Member
When they were swapped into the E6, the sound wasn't as noticeably improved as when I used them to replace the ones in the Tube03. There are 4 more round caps in the pics, two large and two smaller. Not sure what their role is, but I know that with the Tube03, those were also swapped out by some for higher quality and different values, but I recall the type or models.
edit - I think I'm brain farting with "film caps" calling them filter caps...
was looking for more treble and found that by bringing up the 1uf poly caps to nearly 13uf, the treble improved considerably. still, could use a bit more. will try bringing it up a tad more. now, I can hear the flutists take deep breaths and the crowds are clearer in concert music. trumpets are no longer flat sounding. the two 10uf, when adding a 10uf bipolar, the bass increased. without a scope, not sure what I've achieved; except that it does sound much better. in the pic, I've replaced the 10uf for .01uf bipolar. will return them to 10uf.
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drjohnnyfeva
Well-Known Member
I'm interested to know more about this and see some detailed pics with parts and some more explanation of what the different values and changes have made to the overall sound.
I got interested in the mods that others did to the Tube03 and have seen the improvements when I did them myself, so this is really intriguing to me. I'd like to understand the numbers of increasing/decreasing uf in the caps and and how that improves sound. Other than replacing valued parts with higher quality same value parts, I have no reference on the theory behind changing those values improves sound. Please and thank you for any explanation.
hosmer2581
New Member
Yesterday, I received the Nobsound E6 I ordered from Taobao. The packaging was quite basic. After setting it up with my system (which is quite straightforward: a QUAD II Classical reissue), I found the sound to be more pleasing than my original DAC and preamp combo (Audiolab M-DAC+), with enhanced bass and a more fluid sound quality. Like many of my friends have mentioned, the annoying issue is the vibration-induced noise. Additionally, having the input and output RCA jacks on same sides is even more irritating than a ringing bell. The Russian tubes I ordered are still in transit and haven't been received yet. I'll test them upon arrival.
hosmer2581
New Member
Following my previous post about the Nobsound E6 tube preamplifier：
I'm considering whether it would be beneficial to equip it with a linear power supply. I'd like to seek advice from fellow audiophiles on this forum. Do you think adding a linear power supply to the Nobsound E6 is necessary or would significantly improve its performance? I'd appreciate your insights and recommendations. Thank you!
I'm considering whether it would be beneficial to equip it with a linear power supply. I'd like to seek advice from fellow audiophiles on this forum. Do you think adding a linear power supply to the Nobsound E6 is necessary or would significantly improve its performance? I'd appreciate your insights and recommendations. Thank you!
drjohnnyfeva
Well-Known Member
I've wondered the same thing about a linear power supply, but I haven't really investigated it as my power cord that came with the E6 is a USB connection. If I recall, the directions recommend a 2A draw for the unit to perform as desired. I have mine plugged into a 2.5A fast charge phone usb port and it works well. I think it's also 5V? I don't remember, but I would be interested in your results with a linear supply.
bridger2086
New Member
Hey from Sweden, below is my experience with the little E6. I would also like to hear your opinion on the issues I've been having.
The intent was to get a simple tube preamp to control volume of my Pass Amp Camp Amp, which is a single ended single mosfet stage of 8w and 12 db gain.
Hooking the E6 to it, I get hissing audible even from 2-3m from 96db sens speakers (8" Fostex in blh). Than just brushing the E6 lightly anywhere i get ringing (microphonics). Both hiss and ringing are independent of volume set on the E6, but at louder volumes the speakers drive the microphonics (runaway).
Plugging E6 into an integrated amp (20w gainclone), hiss and ringing much reduced at lower volume on the integrated, but show similar behaviour when turning the volume up (again, on the integrated).
I tried a simple 5v/3a wallwart and Shanti LPSU from both 5v/1a and 3a taps. No change.
Ergonomics.. well, absent.
This would be an instant return, if not for the fact that it really sounds rather good. Furthermore, its complimentary to the somewhat forward and lean sounding full range drivers. Bass is plumper and there is more space (not "air"). More euphonic.
Now, did I get a bad example (called "CADISI" now on german amazon)? Can the hiss be fixed? Are unwilling to spend more money (on russian tubes, caps and whatnot), if the design is flawed or unsuitable to drive a simple poweramp.
Appreciate your thoughts!
Alex
The intent was to get a simple tube preamp to control volume of my Pass Amp Camp Amp, which is a single ended single mosfet stage of 8w and 12 db gain.
Hooking the E6 to it, I get hissing audible even from 2-3m from 96db sens speakers (8" Fostex in blh). Than just brushing the E6 lightly anywhere i get ringing (microphonics). Both hiss and ringing are independent of volume set on the E6, but at louder volumes the speakers drive the microphonics (runaway).
Plugging E6 into an integrated amp (20w gainclone), hiss and ringing much reduced at lower volume on the integrated, but show similar behaviour when turning the volume up (again, on the integrated).
I tried a simple 5v/3a wallwart and Shanti LPSU from both 5v/1a and 3a taps. No change.
Ergonomics.. well, absent.
This would be an instant return, if not for the fact that it really sounds rather good. Furthermore, its complimentary to the somewhat forward and lean sounding full range drivers. Bass is plumper and there is more space (not "air"). More euphonic.
Now, did I get a bad example (called "CADISI" now on german amazon)? Can the hiss be fixed? Are unwilling to spend more money (on russian tubes, caps and whatnot), if the design is flawed or unsuitable to drive a simple poweramp.
Appreciate your thoughts!
Alex
I replaced the tubes with the russian versions and mine still had the same runaway ringing/microphonics. I also tried different power supplies with no change. Maybe folks not having this issue are using it at super low volume levels? I'm not impressed at all with it, given this runaway oscillation issue it has.
bridger2086
New Member
Exactly what I'm wondering. When people say "mine has no microphonics or hiss", are they using it into an integrated amp and setting the gain on it to like 3db. I figured the whole point of such a thing would be to drive a poweramp. Is this just never going yo work?
They might be using it at even less than unity gain? I found it to be useless for me as a pre-amp.
drjohnnyfeva
Well-Known Member
I don't know what unity gain is and I'm not sure what 3db gain would be, but...
I've been using mine for a couple years now. I have it going into a Fisher 295 SS Receiver with Infinity speakers. I use it in my classroom for music and for bumping up the volume from my laptop for videos and howto's for students.
When I first started using it, it was in my office system and very nice. I did experience the microphonics, but after I bumped it while in use. Thereafter, I had no issues with it as it stayed in the same spot with the volume on the E6 set at 2-3 o'clock, pretty high. It sounded/ sounds great. No hiss. No microphonics.
The only issue I had with microphonics was when I was using it in a low to no gain line from my PC. I've always needed a gain boost from the PC so that has been accomplished for years with a Little Bear T7 preamp. When I took the Little Bear our of that line, where there had been now hiss or noise, to experiment with a clear signal just to hear the E6, the signal, apparently not being sufficient caused the issues @StepheK and @bridger2086 are having.
I have waited for some confirmation of this, but nothing similar has happened with anyone on this thread. The microphonics in that situation became worse when I tried to compensate for the lost gain of the Little Bear by upping the volume the E6 and then raising the receiver volume which made the ringing escalate exponentially. Lowering the volume of the E6 and trying to raise the receiver volume produced the same out of control ringing escalation.
I used the Chinese tubes out of the box without incident - other than the bump that caused ringing, but had ordered the Russian tubes to replace them in short order simply based on reputation of Russian tubes and my experiences with them in other tube pre's.
All of this said, I continue to use the unit I have and enjoy it. It sounds excellent and to my ears is very similar to the FX Audio Tube 03 with some improvement mods I've made. But the E6 is still in daily use. I would maybe suggest returning the unit and giving another a try as there does seem to be some degree of quality control issues given the feedback from others on this thread with their out of the box experience, or it could be that this unit prefers a good deal of gain to operate properly.
I've been using mine for a couple years now. I have it going into a Fisher 295 SS Receiver with Infinity speakers. I use it in my classroom for music and for bumping up the volume from my laptop for videos and howto's for students.
When I first started using it, it was in my office system and very nice. I did experience the microphonics, but after I bumped it while in use. Thereafter, I had no issues with it as it stayed in the same spot with the volume on the E6 set at 2-3 o'clock, pretty high. It sounded/ sounds great. No hiss. No microphonics.
The only issue I had with microphonics was when I was using it in a low to no gain line from my PC. I've always needed a gain boost from the PC so that has been accomplished for years with a Little Bear T7 preamp. When I took the Little Bear our of that line, where there had been now hiss or noise, to experiment with a clear signal just to hear the E6, the signal, apparently not being sufficient caused the issues @StepheK and @bridger2086 are having.
I have waited for some confirmation of this, but nothing similar has happened with anyone on this thread. The microphonics in that situation became worse when I tried to compensate for the lost gain of the Little Bear by upping the volume the E6 and then raising the receiver volume which made the ringing escalate exponentially. Lowering the volume of the E6 and trying to raise the receiver volume produced the same out of control ringing escalation.
I used the Chinese tubes out of the box without incident - other than the bump that caused ringing, but had ordered the Russian tubes to replace them in short order simply based on reputation of Russian tubes and my experiences with them in other tube pre's.
All of this said, I continue to use the unit I have and enjoy it. It sounds excellent and to my ears is very similar to the FX Audio Tube 03 with some improvement mods I've made. But the E6 is still in daily use. I would maybe suggest returning the unit and giving another a try as there does seem to be some degree of quality control issues given the feedback from others on this thread with their out of the box experience, or it could be that this unit prefers a good deal of gain to operate properly.
amcrabb
New Member
I suspect that the sensitivity and impedance of your speakers/headphones determine whether ringing is audible. There are probably other factors as well. I always use my E6 with maximum gain and occasionally experience ringing with my more sensitive headphones. I suspect my amplifier is also a factor. Since I hardly use the E6 as an actual preamp (just a high gain buffer) it’s not a problem. I’m sorry to hear that it is not working for you. You can see I added foam on the volume knob. But I don’t really have any ringing at all with my inefficient gear.
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bridger2086
New Member
Thanks for the replies gents. Just to reiterate for clarity's sake. Both hiss and ringing are independent of volume setting (aka gain) on the E6. Hiss gets no louder turning the gain up on the E6. Ringing (microphonics) also doesnt get worse with turning the gain up on E6, *if* it isn't initiated, but loud volume from the speakers seems to drive the resonance sooner or later, leading to a runaway effect.
Hiss and ringing seem to be dependant on the gain (volume) of what the E6 is driving (ie the amp). Now amps can have vastly different gains. With a poweramp (amp without volume control), gain is fixed at "maximum" (if it had a volume pot, it would be cranked all the way to 5 o'clock = no attenuation). With an integrated amp (i.e. poweramp with volume control) , you can attenuate the gain, thus seemingly avoiding the issue.
What I am trying to find out is if my unit is somehow flawed or the design of the E6 is flawed. I could say "unsuitable for my application", but producing so much hiss and microphonics through a poweramp that has so little gain as the Pass ACA, can be considered a flaw, I think.
So has anyone had success driving a poweramp of any kind with the E6 (or an integrated with the pot all the way to max) and using the E6 for volume control (ie as an actual preamp / "as advertised"). This would be a pretty big omission to make.
* Thinking about it, the E6 almost acts as a phono preamp without riaa equalisation. It has lots of gain, 16+db i think, but than not quite enough for anything but extremely high output mm carts (DJ stuff).
Hiss and ringing seem to be dependant on the gain (volume) of what the E6 is driving (ie the amp). Now amps can have vastly different gains. With a poweramp (amp without volume control), gain is fixed at "maximum" (if it had a volume pot, it would be cranked all the way to 5 o'clock = no attenuation). With an integrated amp (i.e. poweramp with volume control) , you can attenuate the gain, thus seemingly avoiding the issue.
What I am trying to find out is if my unit is somehow flawed or the design of the E6 is flawed. I could say "unsuitable for my application", but producing so much hiss and microphonics through a poweramp that has so little gain as the Pass ACA, can be considered a flaw, I think.
So has anyone had success driving a poweramp of any kind with the E6 (or an integrated with the pot all the way to max) and using the E6 for volume control (ie as an actual preamp / "as advertised"). This would be a pretty big omission to make.
* Thinking about it, the E6 almost acts as a phono preamp without riaa equalisation. It has lots of gain, 16+db i think, but than not quite enough for anything but extremely high output mm carts (DJ stuff).
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amcrabb
New Member
I tested the E6 with my the volume pot on my amp maxed out (6db of gain). It was exactly as you described your experience with your power amp: static noise, RF, and microphonics are dominant. I don’t believe there is a way to use the E6 as a true preamp with a high powered power amplifier. You would need a second preamp pot in between the E6 and the power amp. Most of the cheap Class D “power amps” these days come with a volume pot. So technically they are integrated amps. I think the E6 would only be useful with a true power amp that is rated at (edited) 3db of gain or paired with lower sensitivity speakers (like @StepheK said above). I think these tubes were designed for portable battery powered military radios… though, I suspect a less noisy and more ergonomic design could be achieved with these tubes for music playback applications. I am suspicious of the way the 5V is stepped up to 110V. Nonetheless, I am happy with the E6 attached to my integrated amp. I have been using it everyday for over a year now.
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I used my E6 with my Dynaco ST-35 tube power amp and it worked fine. Using Russian tubes and being careful not to bump it helped. I liked the sound but it developed a scratchy pot that would only temporarily benefit from cleaning. I have since moved on to a Khozmo passive preamp and could not be happier.
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