Please note the interpolations. Minor rant warning - NOT directed *at* anyone, but because this is one of my pet peeves!
quote="tubes4hifi"]I agree fully with PeterW comments and with the table that Bob provided, which shows 10X the power to get 10db more sound, so as I said before, that's 10 watts to get to 97db
with speakers that are 87db at 1 watt. Just a guess, (grab your db meters everybody), but normal listening level is around 80-85db (I just checked with my db meter).
But let me clarify that when I say 30wpc is plenty (that gives you 100db) I'm also talking about tube power.
Now I realize that watts are watts (to most people) but I'm sure there is at least 90% agreement that 30w of tube power is equivalent to 100w of SS power.
NONONONONONO!!! The actual difference between "tube" power and SS power is in clipping. Output transformers (nor any other isolated-winding transformer) do not pass DC. So, a tube amplifier will clip much more softly (less harsh clattering and noise) than the typical SS amp. Further, older-design SS amps without built-in speaker protection can pass DC, and can damage voice-coils almost instantly in cases of severe clipping. In either case, at clipping the wave forms are severely truncated - how much additional damage is what is in question. But, below clipping, watts is 100% watts is 100% watts.
Personally, I've used amps ranging from 4wpc to 350wpc. I can definitely hear any SS amp clip at 1% over it's rated output. 350w SS distorts just as bad as 10w SS power.
Just so everyone understands how clipping happens: There is a demand made on the amplifier for some period of time that is greater than the RMS (sustained output capacity) of the amp + the amount of energy stored in its capacitor bank(s) if any. In the case of the venerable Dynaco ST70, that is and extreme of eighty (80) watts for longer than one (1) second. In the case of my Citation 16, that is four hundred (400) watts for longer than one (1) second. Less demand = longer sustained time beyond RMS.
It is nearly impossible to hear clipping running a tube power amp at at even 5-10% over it's rated power.
If one knows what to listen for, it is blatantly obvious, but not so harsh - and that is the difference. Clipping with a velvet glove.
Just my own opinion of course, but anything over about 200Hz likely never requires more than 10w, at extremely LOUD levels (100db is LOUD, have you used a meter listening at that level??)
However, yes, especially for music below 100Hz, you're gonna need 10X that much power, maybe even 20X as much power. That's why even super cheap subwoofers start at 100w.
Most decent quality subwoofers start at 250w and up. Not at all uncommon to see subwoofers running 500-1000w (and of course, that's SS, so they'd better have 10x as much power as you think you need!!)
Next Myth: Speaker power ratings. A speaker rated at 25 watts (a great deal) will sustain 25 watts of power for ever, and ever, amen. That is the functional equivalent of putting a 25-watt light bulb inside the speaker, as far as heat is concerned. But, that same speaker will sustain, easily, 1,000 watts for a few seconds. Point being that it is underpowered amplifiers driven to clipping that are far more likely to damage speakers (passing DC, and so forth) than over-powered amplifiers operating within normal listening levels. Sure, if one is listening to head-banging music at ear-bleed levels, then there will be issues. But, I routinely drive my 40-watt AR M5 speakers from a 150 watt amp at substantial levels without fear of damage. If a woofer is well-and-truly rated at 250 watts, that means it can sustain a 500 Hz sine wave at 250 watts pretty much forever. Somehow, that is quite dubious outside of concert hall reinforcement speakers - and that is emphatically a special case.
RE: speaker kits - I've built 6 or 7 pair over the past 20 years. I'm not a wordworker so I'd recommend you get nice cabinents or be satisfied with whatever your level of non-competance is (like mine is very low).
Also, unless you are spending more than $500-600 on components alone (speakers & crossovers) not including any cabinent at all, I don't think you can beat commercially available speakers for under $1000.
I still have a pair of Infinity Primus 360 speakers I bought new ten years ago for $300 that sound better than components I've spend $400 on. PSB makes some great speakers for under $1000, as does Polk.
My latest DIY speakers cost me about $500 in components and another $500 in cabinetry (that still falls far short of a $500 pair of speakers) that are very nice, but side by side,
not any better than a $1000 new pair of PSBs which would take 5 minutes out of a box compared to 30-40 hours of build time for DIY.
I agree with TubeNube, the speaker designs by famed Denmark speaker guru Troels Gravesen are super quality, but will also need cabinents that will require some real word-working ability.
Finished, they will be compare very well to what you could buy for $2500-4000. Component cost on the TQWT is around $1000 plus cabinents.
I like the SP44, looks to be around $1500 just for the components.
Commercially made speakers, as everything else, are a bargain buying used after a few years. Get $10K speakers for maybe $4K.
86db/w, recommended power 20-50w as per Gravesen. [/quote]
Legacy speakers properly maintained will _always_ be a bargain as compared to anything new or that can be built via DIY sources.
I paid $600 for my pair of Magnepan MGIIIas, $200 for my par of AR3as, $40 for my Athena set, $40 for my AR4x, $125 for my M5s, all in excellent, clean and well-maintained condition. That advice is 100% true without reservation.