MrBurns84 Posted December 21, 2010 Posted December 21, 2010 I was reading up on DIY Audio.com and a forum member commented that tubes do not have a sound signature, rather that the electrical characteristics/properties in a tube that contributes towards the surrounding circuitry that determines its 'sound' character. This is a cut out of the post - "At the risk of offending you (and any other sentiment-driven lurkers) I will tell you the truth: a vacuum tube does not have a sound quality, and hence you can not seek one that has a "nice and warm and smooth" sound. Instead they have electrical characteristics that the designer selects and must manipulate by way of the surrounding circuitry in order to influence the overall sound quality of the system. The notion that there are tubes which sound warm, or harsh, or accurate, or smooth, etc., is just nonsense spoken by people who want to sound as if they understand the subject, or who want to be seen as experts to boost their own ego, or they want to sell you something. The tube in the linked schematic is an impedance converter - it presents a high impedance at the input so as to not load down the source, and creates a low(-ish) impedance at its output to drive the chipamp. I am surprised that the chipamp needs this impedance converter ( / buffer). The tube in this configuration will reduce the size of the input signal a little (which is a fact, but it may not be important), and it will introduce a little distortion. You may in fact like that type of distortion or you may not even notice it. If you are very lucky the tube specification and the opperating point set by the designer (via the surrounding components) may contribute towards a sound that you interpret as 'warm and smooth'. Let's hope so ." Is this fact or fiction? cheers
Once was an audiophile Posted December 21, 2010 Posted December 21, 2010 i find this funny imho he must be an engineer
monaro8 Posted December 21, 2010 Posted December 21, 2010 Surely this is just semantics?? If a given tube 'alters' or 'affects' the sound in a particular amp, if it sounds warmer, darker, brighter, duller etc., then does it really matter if one says "the valve" has that characteristic..eg. warm sounding. If it's the amplifier circuitry which when mated with that valve, rather than the valve itself, most would agree that the valve itself 'did' contribute to the warm or dark sound being reproduced. To be overly technical, which is what this article is, does not take away the fact that there are different characteristics with different valves, no matter which way you put it. Otherwise, if this comment is to be taken 'literally' then it would imply that no valve makes any difference to any sound reproduction???? That's my opinion anyway. Vanch...:nana
Todd Posted December 21, 2010 Posted December 21, 2010 Hi Shogo, it seems to me an amazingly subtle point he/she is making (and with disproportionate passion). Of course a tube has no 'sound quality' in and of itself, but only in the context of an amplifier circuit. If enough people observe the result of a particular tube (in the context of an amplifier) as being sound of a particular quality, surely it is acceptable shorthand to describe the tube in terms of the quality it generally produces? Methinks the original poster is a sophist... or am I missing something?
MrBurns84 Posted December 21, 2010 Author Posted December 21, 2010 Yes, i thought it was rather amusing, but i should give you all the facts to this: http://www.diyaudio.com/forums/tubes-valves/146362-recommend-me-warm-smooth-sounding-6922-6dj8-ecc88-equivalent.html
Once was an audiophile Posted December 21, 2010 Posted December 21, 2010 diyaudio is a very funny place measurements are very popular on that site
Zaphod Beeblebrox Posted December 21, 2010 Posted December 21, 2010 (edited) All active devices introduce some distortion. Be they valves, transistors, MOSFETs, IGBJTs, whatever. As a general rule, some devices introduce less distortion than others. Again, as a general rule, the order of amplifying devices from low to high distortion are: BJTs (regular transistors) Triodes IGBJTs MOSFETs Pentodes/Tetrodes This, of course, is before external NFB is applied. When external NFB is applied, everything changes. Additionally, the type of devices used, are often less significant than the topology employed by the designer. A really well designed push pull Pentode amp can deliver lower levels of distortion than a poorly designed Single Ended Triode amp. OTOH, a transformer coupled, SE BJT amp can sound very similar to a SE Triode amp. It's the topology that rules, not the devices. Valves can easily sound harsh, hard and strident (the same characteristics associated with poorly designed transistor amps), if the designer fails to attend to specific design issues. That said, there is one aspect attributable to valve amps (usually in low level areas) that some listeners like and others hate. That characteristic is called 'microphonics'. It's what gives many valves amps a larger than reality sound stage. And, when playing poorly engineered recordings through such amps, the result can be more pleasing than when playing though an amp that has no microphonic effects. Edited December 22, 2010 by Zaphod Beeblebrox Brain fart
Decky Posted December 21, 2010 Posted December 21, 2010 +1 It is all in the circuit design. Nelson Pass spent a lot of his time trying to show people how solid state devices can "sound" as tubes.
andyr Posted December 21, 2010 Posted December 21, 2010 Methinks the original poster is a sophist... or am I missing something? (In my best Homer Simpson voice) "Mmmm, so.ph.is.t ... is that just another term for wanker?" :nana Regards, Andy
ArthurDent Posted December 22, 2010 Posted December 22, 2010 It's the topology that rules, not the devices. +1 It is all in the circuit design. So different valves of the same type (ie. 12au7) from different manufactures all measuring within spec in the exact same circuit will all sound exactly the same. And if there are any differences then it all comes down to varying degrees of microphonic effects.
Kamikaze Posted December 22, 2010 Posted December 22, 2010 Tubes have different sound characters. When I flick it with my finger nail, they all sound slightly different. ;p
Zaphod Beeblebrox Posted December 22, 2010 Posted December 22, 2010 (edited) So different valves of the same type (ie. 12au7) from different manufactures all measuring within spec in the exact same circuit will all sound exactly the same.And if there are any differences then it all comes down to varying degrees of microphonic effects. That was not what was written. Take note of the words: "as a general rule" (soon to be emphasised). (Global) NFB reduces the effects of different components in a product. Hence, the claim that topology rules. IOW: In a circuit that employs large amounts of global NFB, the differences between brands of valves will diminish significantly. Edited December 22, 2010 by Zaphod Beeblebrox Brain fart
frankn Posted December 22, 2010 Posted December 22, 2010 That was not what was written. Take note of the words: "as a general rule" (soon to be emphasised). (Global) NFB reduces the effects of different components in a product. Hence, the claim that topology rules. IOW: In a circuit that employs large amounts of global NFB, the differences between brands of valves will diminish significantly. What's a NFB, global or not? I'm new and need an acronym translator! Regards Frank
ehtcom Posted December 22, 2010 Posted December 22, 2010 "At the risk of offending you (and any other sentiment-driven lurkers) I will tell you the truth: a vacuum tube does not have a sound quality, and hence you can not seek one that has a "nice and warm and smooth" sound. Instead they have electrical characteristics that the designer selects and must manipulate by way of the surrounding circuitry in order to influence the overall sound quality of the system. The notion that there are tubes which sound warm, or harsh, or accurate, or smooth, etc., is just nonsense spoken by people who want to sound as if they understand the subject, or who want to be seen as experts to boost their own ego, or they want to sell you something. The tube in the linked schematic is an impedance converter - it presents a high impedance at the input so as to not load down the source, and creates a low(-ish) impedance at its output to drive the chipamp. I am surprised that the chipamp needs this impedance converter ( / buffer). The tube in this configuration will reduce the size of the input signal a little (which is a fact, but it may not be important), and it will introduce a little distortion. You may in fact like that type of distortion or you may not even notice it. If you are very lucky the tube specification and the opperating point set by the designer (via the surrounding components) may contribute towards a sound that you interpret as 'warm and smooth'. Let's hope so ." Maybe this guy should change his name to Captain Obvious. It's a bit like stating "resistors don't sound different, just resistance does" There are many different measurable variables in a valve, the combination of these is what gives the valve it's sound signature.
Once was an audiophile Posted December 22, 2010 Posted December 22, 2010 In a circuit that employs large amounts of global NFB, the differences between brands of valves will diminish significantly. i disagree zb my amp uses nfb and valves do sound different some are night and day
Once was an audiophile Posted December 22, 2010 Posted December 22, 2010 +1 It is all in the circuit design. Nelson Pass spent a lot of his time trying to show people how solid state devices can "sound" as tubes. -1 no they dont they still lack the magic
andyr Posted December 22, 2010 Posted December 22, 2010 i disagree zb my amp uses nfb and valves do sound different some are night and day Does it use local NFB ... or global NFB? Does it use large amounts ... or a little? ZB was referring to amps which use large amounts of global NFB. Regards, Andy
Once was an audiophile Posted December 22, 2010 Posted December 22, 2010 Does it use local NFB ... or global NFB? Does it use large amounts ... or a little? ZB was referring to amps which use large amounts of global NFB. Regards, Andy i will find out and post
everyones_shadow Posted December 22, 2010 Posted December 22, 2010 Isn't there an easy test for this? Many amps can use related output valves with no change (6550/KT88) some amps can use a wide range of more distantly related valves (KT66-120, EL34) with just a change in bias current and al least one company - PrimaLuna - makes an amp where you can mix and match output tubes eg have a KT66, 6550 and EL34 in the same amp at once. Arrange a GTG with a suitable amp and a box of tubes and listen (and or measure). Cheers ES
Zaphod Beeblebrox Posted December 22, 2010 Posted December 22, 2010 i disagree zb my amp uses nfb and valves do sound different some are night and day ALL amplifiers use NFB. Every single one. SOME amplifiers use zero GLOBAL NFB. SOME use very low levels of GLOBAL NFB. The latter topologies (be it SS or valve) will readily expose differences between active (and passive) devices. LARGE amounts of Global NFB tends to erase small differences in active and passive devices.
ArthurDent Posted December 23, 2010 Posted December 23, 2010 Arrange a GTG with a suitable amp and a box of tubes and listen (and or measure). A "tube rollin" day no less. Here's a colourful write up of such an event... http://www.6moons.com/audioreviews/tuberolling/tuberolling.html Please note that the pre used uses no feedback so YMMV, but then no feedback or low feedback designs are as a general rule pretty common with valve gear.
RoHo Posted December 23, 2010 Posted December 23, 2010 diyaudio is a very funny place measurements are very popular on that site Actually The Tube Forum of DIY Audio is an excellent resource. They actually discuss tube CIRCUITS and how they sound, not much measurement at all. Isn't there an easy test for this?Many amps can use related output valves with no change (6550/KT88) some amps can use a wide range of more distantly related valves (KT66-120, EL34) with just a change in bias current and al least one company - PrimaLuna - makes an amp where you can mix and match output tubes eg have a KT66, 6550 and EL34 in the same amp at once. Arrange a GTG with a suitable amp and a box of tubes and listen (and or measure). Cheers ES It's a good idea but what you will end up finding is the best tube for that amplifier. You can't allow for the fact that , say, an EL34 and a KT66 have slightly different "ideal" operating conditions eg plate voltage or output transformer impedance. Your amp will probably "like" a certain tube more than others.
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