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New member Username: BluebirdPost Number: 1 Registered: Aug-05 | I have recently bought a 50 watt valve amplifier and preamp because I was under the impression that the sound would be better. It has 4 ohm,8, and 16 ohm outputs.It is a lovely looking unit. At this point I,m driving two 16 ohm Altec 605B,s. I also have a Yamaha AX400 amp (55 watts per channel) which I would have to say provides a much clearer sound. Should I give up on the valve amp? The preamp that I have for the valve amp has only a vol control and therfore no adjustment for treble and bass.Your help would be appreciated. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5039 Registered: May-04 | You'll have to be a little more specific about what you're hearing. |
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Gold Member Username: John_aLondonU.K. Post Number: 3621 Registered: Dec-03 | Yes, "clearer" does not convey much. Also more about the "valve amplifier and preamp", please! Separately and together. Make; whether new or old. Etc. etc. There are many possibilities. There is a good chance that someone here will be familiar with them. The high impedence of the speaker means you have all the output taps to choose from; they should be rated at the same, or a lower value. |
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Bronze Member Username: BumblebeePost Number: 19 Registered: Jul-05 | When does one use 12ax7, 12au7, 12at7? Many, many thanks. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5042 Registered: May-04 | bb - When the circuit design specifies each tube. You are selecting between the amount of gain in each tube. |
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Bronze Member Username: BumblebeePost Number: 20 Registered: Jul-05 | Jan, I see. I see. Can I ask some more? (I just did) Can I just replace stock tubes w/ new ones? What is bias setting? |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5043 Registered: May-04 | Read thru the "Tube Talk" thread and you'll find a lot of answers. As long as you are staying with the same type of tube (12AX7 to 12AX7) you can replace any rectifier, input or driver tube without any adjustment to the amplifier, pre amplifier, tuner, CD, etc. The operational characteristics for small signal triodes are established and do not vary enough from manufacturer to manufacturer. You will, however, find a noticeable difference in sound quality among different manufacturer's tubes and even within a group of similar tubes. One 12AX7, while designed to the same overall specs as every other 12AX7 may be designated for low noise, low microphonics, military use or other qualities. You will find letter or number dsignations behind the 12AX7 type to differentiate these special purpose tubes. 12AX7 is a designation given to a tube manufactured in the US or meant for use in the US. Other countries will make similar tubes that swap out with the 12AX7 but have different letter/number designations. (http://www.hktubeaudio.homestead.com/files/tubecode.html) In small signal tubes, these can be interchanged with no problems (typically). When you get to large signal output tubes, you need to be more careful about what goes where. While you can generally swap a KT88 for a 6550, all output tubes will run at different bias levels. Bias can be thought of as the voltage or current through one section of the tube's elements that attracts the oppositely polarized electrons to flow from another element thus affecting gain. Read the last week's worth of entries in Tube Talk for more on bias. The subject of tubes covers way too much territory to give definitive answers too many times. Read up a bit on tubes and you'll get a better idea of what to expect. http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm http://www.vintagelectron.com/ http://www.lh-electric.4t.com/tutorials.htm http://www.tpub.com/content/neets/14178/ http://www.vacuumtube.com/tubes.htm http://hometheater.about.com/od/vacuumtubeaudio/ http://www.tubedepot.com/ http://www.tubedepot.com/whisbipo.html http://www.worldtubeaudio.com/ If you cannot find the information you desire somewhere on the world tube depot site, it probably isn't there to be found. |
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Silver Member Username: CheapskatePost Number: 205 Registered: Mar-04 | you might prefer the treble speed and extension of solid state and be calling that clarity, while tube fans just love the "sweetness" of tube treble which often times is somewhat rolled off. 16 ohm speakers are one heck of a wierd load! i've never heard of a 16 ohm or higher speaker outside of public address speakers. tubes are just a different type of sound... some love it... some hate it. i'm not into "warm" sound at all. i don't think i'd like tube sound at all. tubes are also known for being flabby in the bass too. their major draws are midrange and imaging. they usually have higher levels of distortion too. (though in less objectionable harmonic regions) from everything that i've read... soid state = "clarity with sterility" and tubes = "organic sound" |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5077 Registered: May-04 | Dear budget minded, While you and I seem most often to be on the same path towards good sound, I feel obligated to inform you of the existence of a speaker with "one heck of a weird load". One of the most successful mini-monitors in the history of audio is a 15 Ohm load. The BBC designed LS3/5a was originally designed to this spec and continued in production as exactly that same specification until, due to the problems faced by maintaining production for the BBC design and their growing consumer market, KEF was forced into reconfiguring the X-over for the LS3/5a some twelve years after its intial design. With the redesign the 3/5a became an 11 Ohm load. The total numbers of LS3/5a's sold over the last thirty years (totalling well over 100,000 pairs) is about equally split between the 15 Ohm and 11 Ohm varieties. The 3/5a is considered one of the most tube (valve) friendly speakers ever sold. As the owner of a pair of 15 Ohm Rogers LS3/5a's that are still in daily use (as are the majority of those 100k pairs sold), I felt I should inform you my speakers are very nearly taking offense at the implication that a 16 Ohm load is in some manner or fashion "weird". They have asked that you ammend your statement to accommodate the very normal state of impedance they find themself in. They do not consider themself to be "weird" or out of the ordinary in any way, nor do the owners of this classic monitor speaker. Your use of words would imply an insensitivity (no pun intended) to any speaker of higher than an 8 Ohm total impedance. As you are undoubtedly aware, many speakers have an impedance which, at some point in their response curve, will cross above your "socially responsible" 8 Ohm impedance. While these speakers are not considered "weird" in your estimation, the diminutive 3/5a reaps your scorn for its preference to remain an honest load which seldom strays from its appointed path. Speaking on behalf of the 3/5a's, I feel your implication that any speaker not meeting your "approved" specification for minimal resistance to the status quo should be considered "weird" is dammaging to the reputation of all speakers which fall outside of the norm you would so freely define. It is this very freedom you so easily abuse which the 3/5a celebrates and honors by its desire to serve its purpose in the audio community without further impunity from those who would set rigid guidelines for a speaker's behavior. On behalf of all the 15 Ohm LS3/5a's, and all speakers of any sort, I ask you, sir, to rescind your statement referring to the "one heck of a weird load" these speakers represent to the world at large. Surely, you can see, by examining the facts of other speakers' behavior; as the limits of impedance are approached, toyed with and crossed repeatedly, that a speaker proud of its 15 Ohm load is not fit to be held in such ridicule. I have no doubt you are aware of the future implications should all speakers begin to present less impedance to the establishment. If you will retract your statement and amend its contents to accept the idea that diversity is what makes this hobby great and that falling into the "company line" might possibly be held as less than acceptable, the 3/5a's of the world would feel no need for further action on this issue. We appreciate your prompt and couteous response. Assuming you are willing to meet our request, no further correspondence on this issue shall be required. Sincerely, Jan B. Vigne |
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Gold Member Username: John_aLondonU.K. Post Number: 3641 Registered: Dec-03 | There is another thread where people are taking shots at the LS3/5a, bm. A man has to defend himself. The bottom line is tubes rock. I think that is the way to phrase it. If st's amp has 16 Ohm taps, it can't be all bad. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 5089 Registered: May-04 | Fair'nuff! |