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Post by mgbpuff on Jun 10, 2013 15:10:04 GMT -5
I've read that a damping factors in excess of 20 have inaudible affect on the sound. Some of the best tube amps have damping factors approaching 20, in fact my Marantz 8b has a damping factor slightly in excess of 20 as stated on the original tech checkout card. The distortion spec on it at 35 watts per channel is 20-20khz +- .04%THD. It is a pentode EL-34/6CA7 pp design with feedback. Some tube diehards dismiss it as sounding too neutral, lacking the SET bloom. Some have converted it to triode operation because of this at half the watt rating, but I never wanted to change it. I always have enjoyed its sound just as it was designed.
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Post by brubacca on Jun 10, 2013 15:19:39 GMT -5
Keith,
Would there be a way to make a pre-amp that depending on tubes that a end user rolled into it could be neutral or "tubey" sounding?
This would allow the end consumer to tailor the sound to their liking.
Another idea (if even possible) would be to have two full sets of pre-amp tubes in the unit. One set for a more neutral sound another set that sounds "tubey". For really substandard recordings the more tubey sounding tube may be a better fit. Have a switch to select which one. I'm thinking like the Peachtree Nove Pre, which has the ability to run the signal through the tube or bypass it altogether.
Not sure if technically this is possible or reasonable.
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DYohn
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Post by DYohn on Jun 10, 2013 15:33:59 GMT -5
That's what tube rolling is all about, brubacca. Trying different flavors of tubes in the gear to discover what combination you prefer. It's why using tubes can be much more engaging than just a way to enjoy music.
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Post by jmilton on Jun 10, 2013 17:52:58 GMT -5
My new tube earbuds arrived today. They had a nice warm sound, but had to take them out after about five minutes. Too hot!!!
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Post by pedrocols on Jun 10, 2013 19:17:06 GMT -5
Myself, based on my taste for sound or music, replaced my USP-1 for a tube preamp after the first 10 seconds of the first song I played....
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Post by danr on Jun 10, 2013 19:58:54 GMT -5
Interesting topic Keith. I honestly don't "know" what a tube is suppose to sound like, so I am not sure my limited experience with tube gear is indicative or not. Here's all I know. I heard some sort of Sonic Frontiers tube amp driving B&W Silver Sigs. I would describe it as velvety & seductive, with great imaging that seemed to float in space. Again, I don't know if this was real tube sound or purposely engineered to sound that way. I do know that at the right price, I would try some Emo tube gear for music, but there is no way I'll be selling my XPRs any time soon. In fact, they're gonna have to pry my XPRs from my cold dead hands. For me, if your tube gear sounds like what I heard, I feel like Emo tube product will be a nice change of pace and a "hobby" for me.
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Post by GreenKiwi on Jun 10, 2013 22:50:09 GMT -5
Keith Thanks for all the tube info !! This is great ! I for one have an interest but unfortunately living in the middle of nowhere its hard to demo items like tube amps etc. I had an idea, a couple years ago Musical Fidelity brought out the tube buffer and it sold like hot cakes back then, I read a lot of impressions and they were greatly varied most likely as you discussed earlier with it being a complete different sound. Maybe this would be a good starting point for Bob Carver and Emotiva. A simple buffer would be a low cost way for people to check out the sound at a relatively low price. You know, I would be very tempted by this. Might have to be balanced, with a simple trigger on/off so it could be bypassed. I'd love to have tubes in my system again. Something like this. www.purityaudiodesign.com/purity%20buffer.htmBut maybe a little cheaper than the $8k they want.
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Post by AudioHTIT on Jun 11, 2013 0:52:32 GMT -5
I think this is a good premise for a thread, people should have a better idea what tubes are about and whether their system might benefit from them, or not. Speaker and amp synergies are always important, I think more so with tube amps (though I know this is about tube sound, not amps per say).
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flyhigh
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Post by flyhigh on Jun 11, 2013 9:11:17 GMT -5
"Tubes on the Go". (The original I-Pod)
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bootman
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Post by bootman on Jun 11, 2013 16:00:06 GMT -5
Tubes should sound like this: If it doesn't you need to add more tube gear.
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KeithL
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Post by KeithL on Jun 12, 2013 1:50:46 GMT -5
The reality is that it's a bit more complicated than I made it sound. For one thing, damping factor actually varies with frequency in a given circuit, so the single number given is not the whole story. For another, what damping factor actually "is" is the ability of the amplifier to "short out" back EMF generated by the speaker. (A speaker acts both as a motor and a generator; when the amplifier is driving, the speaker acts as a motor; when the amplifier stops, the energy stored in the speaker makes it want to keep moving, and the speaker acts as a generator; it is the ability of the amplifier to "short out" the output of this "generator" that allows it to control the speaker.) The reality is that some amplifiers react to this back EMF differently than others - and not always linearly. Because, with a tube amp, all of this is happening through an output transformer, which itself has an impedance that varies with frequency and also significant phase shift, the results can be even more complex. Some speakers probably won't sound any different with amps with damping factors anywhere above 20, but others (especially ones with heavy woofer cones and soft surrounds) will sound different with different amounts of damping until you get above 100 or so. Pentodes tend to have lower distortion than triodes, feedback increases damping factor, lowers distortion, and improves linearity, and your Marantz 8b is ultralinear (an extra winding on each output transformer connected to a grid on each output tube provides local feedback and lowers distortion even more). In short, your Marantz is a relatively modern tube amplifier which was designed to minimize coloration rather than the opposite... (I always find it humorous how people try so hard to "get back" to SET sound today, when old-time tube designers worked so hard to eliminate all the flaws that make a SET amplifier sound the way it does.) I'm sure your Marantz sounds very nice (and not especially "tubey"), but, I'm equally sure you would notice a difference in the bass with an amplifier with a higher damping factor - but only with some speakers. I've seen a few spec sheets that claim THD more in the range of 0.1% at mid frequencies and 0.5% from 20-20k - at full power - which is still quite respectable for a tube amp. (And these will be the factors that make it sound different than a good solid state amplifier.) The 8b is a real classic, and probably far better than all but the best modern tube amplifiers; enjoy it. I've read that a damping factors in excess of 20 have inaudible affect on the sound. Some of the best tube amps have damping factors approaching 20, in fact my Marantz 8b has a damping factor slightly in excess of 20 as stated on the original tech checkout card. The distortion spec on it at 35 watts per channel is 20-20khz +- .04%THD. It is a pentode EL-34/6CA7 pp design with feedback. Some tube diehards dismiss it as sounding too neutral, lacking the SET bloom. Some have converted it to triode operation because of this at half the watt rating, but I never wanted to change it. I always have enjoyed its sound just as it was designed.
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KeithL
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Post by KeithL on Jun 12, 2013 1:56:13 GMT -5
In one sense, that would be difficult....by designing the circuitry to specifically be sensitive to tube characteristics, it would become difficult to find a combination where the "interactions" would cancel out to neutrality. If it were designed to not be interactive, then you wouldn't even be able to tell there was a tube involved. Offering a switch to switch the tube in and out would, of course, be easy. We are, however, looking into ways to offer sound that could be adjustably tailored... more on that later. Keith, Would there be a way to make a pre-amp that depending on tubes that a end user rolled into it could be neutral or "tubey" sounding? This would allow the end consumer to tailor the sound to their liking. Another idea (if even possible) would be to have two full sets of pre-amp tubes in the unit. One set for a more neutral sound another set that sounds "tubey". For really substandard recordings the more tubey sounding tube may be a better fit. Have a switch to select which one. I'm thinking like the Peachtree Nove Pre, which has the ability to run the signal through the tube or bypass it altogether. Not sure if technically this is possible or reasonable.
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Post by ocezam on Jun 12, 2013 7:29:08 GMT -5
Understood, and appreciated. This is why when people ask me about tubes I always tell them it's different strokes for different folks. I never use tubes in HT, it's exclusively solid state for the high watts-per-dollar and fast transient response with low distortion that only a SS amp can provide, but I prefer using tubes in my 2-channel system because I like the sound of analog warmth and what that does to most music X 100! Perfectly stated IMHO. ...
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Post by ocezam on Jun 12, 2013 7:33:43 GMT -5
I do know that at the right price, I would try some Emo tube gear for music, but there is no way I'll be selling my XPRs any time soon. In fact, they're gonna have to pry my XPRs from my cold dead hands. In this case, consider buying a decent tube preamp to front your XPR's. It can be the best of both worlds. I've done it for years, although I am considering tube power amps in the future. I'd need more efficient speakers first. ...
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KeithL
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Post by KeithL on Jun 12, 2013 13:26:21 GMT -5
There is another interesting phenomenon that I hear with tube power amps - but not with tube preamps (which suggests that it may be related to output transformers, or to the geometry of the construction of output tubes). Many tube power amps sound like they smoothe (or "blur", or "soften") the high frequencies. I'm *not* talking about a rolled off high end, which some tube amps also have. With this phenomenon, the amp will measure as having a flat frequency response, but the high frequencies sound "smooth" or "soft". [Imagine looking at a color picture through a soft focus filter; all the colors are there, and in the right proportions and brightness, but it looks more like a water color painting than a photo. This is what I imagine that picture would "sound" like.]
If you like "analytical" sound, then this will probably annoy you. But, if you don't (or if what you're listening to, or your source component, sounds too "harsh" or "grainy") then it will add a pleasantness and smoothness to the sound. In fact, it might even make a bad digital recording sound better, or an overly bright speaker sound "airy" rather than "glaring" (just as a soft focus filter can make uneven skin in a portrait look "romantic"). It certainly could be what some tube lovers are talking about when they say that a tube power amp "never sounds harsh or fatiguing". I have never seen this effect properly explained, but to me it sounds like some sort of time effect - possibly due to the phase shift in a typical output transformer. (One friend of mine, who is a tube fan, suggested that it may be related to the path differential between the cathode and different areas of the plates in the output tubes... or it could be related to the "space charge" in the tubes.) Whatever the cause, it is a characteristic of many tube power amps, and another way in which they sound different than most solid state ones.
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Post by paintedklown on Jun 12, 2013 14:04:07 GMT -5
Keith, this has been one of the most educational threads I have ever read in regards to audio, and certainly THE most educational thread I have ever read about tube gear. Thank you for your input and contribution, it has been an invaluable "primer" on tube gear for me. Like many other guys that are relatively new to the hobby, I have always seen tube gear as mysterious pieces of equipment reserved only for the ultra wealthy "golden eared" audiophile. I will admit, that I am still very nervous with the idea of buying tube gear, and then attempting to swap the tubes myself (tube rolling), due to not wanting to fry anything, or get an electric shock! However, along with this fear, also comes the biggest fascination that tube gear carries for me, the fun of tube rolling to find the sound that works best for you, your system, your room, your listening habits, etc. I have heard that swapping tubes, in even modestly priced tube gear, can have a great effect on the sound. Can you please dive into tube rolling a bit? Maybe talk about the process of swapping the tubes, properly biasing them, and what sort of results we can expect from this. Thanks. EDIT: I want to note here that I have never heard any tube audio gear in my life, not even so much as a tube buffer. I have heard (and own) a tube guitar amp (Epiphone Valve Jr.) and a tube based mic pre (ART Tube MP), both of which are ultra low cost pieces used for recording.
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Post by harrison20 on Jun 12, 2013 15:29:02 GMT -5
In a prior post it was mentioned that Emotiva is NOW producing both tube and SS gear. So the obvious question is when will the tube gear be available?
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Post by FireFly on Jun 12, 2013 21:23:34 GMT -5
Keith,
I own both and like both for various different reasons. If a Tube Pre/Amp is done right it can sound just as good as solid state gear, the problems is a lot of it is made overseas in China and to my ears not very good. Rogue Audio in the US does a very good job with their Hybrid designs and I do like some Cary gear as well. The problem with tube gear lately is a lot of tube manufactures act as if their tubes will last for 5000-10000 hours. Currently running a Metis Tube Pre/Amp with a Emotiva XPA-2 on some Dynaudio's with excellent results. I also use a Musical Fidelity A5 Pre/Amp and I have a Int. Rogue Tube Amp that one some awards at the 2013 CES and a ton of people had no clue it had tubes in it till some one told them. ;)
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Post by ocezam on Jun 14, 2013 7:56:38 GMT -5
In a prior post it was mentioned that Emotiva is NOW producing both tube and SS gear. So the obvious question is when will the tube gear be available? It's already available due to Emotiva's purchase of Bob Carver's company: www.bobcarver.com/Although many of us are hoping for a line of tube products with a lot lower cost, possibly being marketed under the Emotiva name.
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Post by ricardojoa on Jun 20, 2013 17:29:49 GMT -5
Hi Keith,
how about a discussion on tube power amps and speaker impedance matching and impedance curve? It seems that tubes amps does not like big swing in impendance curve. Also, tube power dont increase when ohm lower. Maybe you can elaborate a little further or correct if any wrong info is put out.
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