DrDeville said:
I think ashok's point is that a musical signal of one watt average level can have transients, momentary power levels, many many times greater. And I agree.
But shouldn't any well designed one watt amplifier be able to handle that?
Sheldon said:
Okay, let me clairfy, and see if we actually agree.
First, by "well designed" I do not mean a typical transitor amp, but rather the sort of audiophile amp folks here respect.
The question that remains is this: Isn't a well designed amp rated at X watts average (say a 5 watt SE triode) able to produce whatever output voltage is required for the transients in a music signal of that average power level?
This maximum voltage could be calculated from the dynamic range of the source--which I'd think would be fairly straightforward for digital sources given their strict dynamic boundaries, less so for analog.
I'm genuinely curious, and agree that handling transients well--by handling them without overload (or overloading gracefully and recovering quickly)--is a hallmark of a good amp.
I'm just wondering if most audiophile amps can do that at their rated average output levels?
Forgive me if I'm thread-hijacking, though I think this is relevant to the question of bi-amping, as it impacts amplifier requirements.
Amps are generally rated at their maximum. Audio enthusiasts use reasonable terms to define maximum. A good amp will achieve that power without trouble. From there we can state that we could reproduce any music through it that has transients within the rated power.DrDeville said:
Some valve amps can be pushed even further with only minor losses in the percieved sound quality, whereas the typical solid state amp needs really to stay within the rated power.
leimaster said:
My opinion is that an active crossover is a much better solution than feeding full-range signals into speakers with bi or triamp connections.
In either case there's a crossover mucking up the signal, and I believe active crossovers are a better (and more costly and complex) solution.
Sending a full-range signal to the bi/triamp speaker connections has a number of problems. First, each amp has to amplify a full range signal, so unless all your amps are the same power, one will overload first--no smaller amps for the high end, no sweeter tubes for the smaller amps. (unless of course your tri/biamp speaker connections require separate bass and treble signals, and now you're back to needing an active crossover)
Second, each amp has to amplify a full range signal, and is subject to IM distortion between base and treble signals.
Third, the speaker's passive crossover network remains in place (otherwise the bass would blow out the tweeters, etc.) and passive crossovers are far from uncolored, and present a complex reactive load to the amplifier, muddying the sound.
These are all bad things, but it's an easier way to go.
Putting an active crossover between the preamp and amps splits the signal into frequency bands, and each amp gets only the frequencies it needs and is hooked directly to it's driver, with no passive crossover.
This means the amps can now be sized accordingly--sweeter tubes for the high end--and each amp has less signal to handle and is hooked directly to it's driver.
I hope this helps, but I've only scraped the surface. If you're interested, I can give you some links. I suggest you read up if you do this. Oh, and Broskie's Tubecad site has been fantastically useful to me.
ak_47_boy said:
Generally an active crossover's main purpose is to split the full range signal into specific frequency bands. It may also have a little gain control for the individual bands, in order to equalize tonal balance with particular speakers and amplifiers.
Since this overlaps with a pre-amp's functions, some active crossovers can be used without preamps, as a substitute for a preamp. For example, Marchand Electronics makes some tube crossovers that can be used this way.
Here is JB's write up on them.
http://www.tubecad.com/articles_2001/Tube-Based_Crossovers/Tube-Based_Crossovers.pdf
http://www.tubecad.com/articles_2001/Tube-Based_Crossovers/Tube-Based_Crossovers.pdf
DrDeville said:
No, not without clipping (soft or otherwise).
DrDeville said:
Yes, and if you listen to music where the peaks are not much higher than average, extra power beyond average listening levels might not be noticed. But if you listen to well recorded classical music, a more powerful amp might sound more dynamic.
Sheldon
Sheldon said:
Wow, that really surprises me--not to say that I don't believe you. I would think that would be a basic requirement for an audiophile amp of a given average power level rating--to be able to handle any and all transients in a musical signal of that average power level.
Asked another way--do most audiophile amps routinely clip in normal listening, i.e. at moderate volume levels?
I know that one of tubes' advantages is clipping benignly and recovering quickly. I just didn't think audiophile amps clipped much at moderate volume levels.
Again, sorry if I'm hijacking. I'm just interested.
DrDeville said:
It all depends on the system. And it isn't a quality issue. Amps aren't rated at an average power output, they are rated at maximum. For an audiophile amp, it's probably assumed that you won't be running it near the max on a continuous basis. For club amps, it may be a different story. The manufacturer can't know what volume level is moderate for you or your system. Back in the thread it was suggested that the peak power requirements for tweeter, mids, and bass are all similar, even though average power requirements are much more for bass and mids than for the tweeter. This assumes, of course that efficiency is similar for all three (which it usually is not, particularly if eq to boost the low end is required). I think Indm covered it pretty well.
lndm said:
A little further explanation on valve amps: SE amps with no or minimal feedback can be pushed beyond their rating, as it is usually defined as power output at an arbitrary distortion limit. This limit is usually below, not right at, the start of clipping. If you are willing to accept more distortion, you can push it somewhat harder - but not that much harder. PP amps with significant feedback will clip more abruptly, so can't be pushed as much beyond the rated max. Whether you will hear enough difference between an amp running near it's limits or one running at a few percent of it's limits, to justify the extra expense, I can't say. If you really want to know, try it both ways.
Sheldon
I think the ultimate system should NOT clip at at any level that the listener wants to listen to.
So soft clipping or equivalent is NOT a solution but a way to get away from large transient reproduction at low cost (?) or effort.
The result would not sound like a real unclipped signal.
Low power tube amps are to be used with high sensitivity speakers with ( maybe ) horn loading . So , a system with 104 db/ watt/m sensitivity speakers and 5 watts per channel amp , it is equivalent of a 88db/watt/m speaker with a 200 watt per channel amp with respect to spl levels.
So using a 5 watt amp with low sensitivity speakers is like driving a car with pedals .
Every design has its proper application. Can't get away from that.
So soft clipping or equivalent is NOT a solution but a way to get away from large transient reproduction at low cost (?) or effort.
The result would not sound like a real unclipped signal.
Low power tube amps are to be used with high sensitivity speakers with ( maybe ) horn loading . So , a system with 104 db/ watt/m sensitivity speakers and 5 watts per channel amp , it is equivalent of a 88db/watt/m speaker with a 200 watt per channel amp with respect to spl levels.
So using a 5 watt amp with low sensitivity speakers is like driving a car with pedals .
Every design has its proper application. Can't get away from that.
Like the single-ended, class A solid state amp with no feedback, which is the cat amongst the pigeons having qualities that many hastily attribute to valve amps.
DrDeville, I don't feel that behaviour like you describe makes an amp inferior. I think what you are explaining is a matter of semantics. A cheap 50W amp will produce similar levels to an expensive one.
For some fun, try listening to music whilst your oscilloscope is on the speaker terminals. BTW, say, 50W of average music power often makes for some quite loud listening.
ak_47_boy, perhaps you could fit a KT66 in there.
DrDeville, I don't feel that behaviour like you describe makes an amp inferior. I think what you are explaining is a matter of semantics. A cheap 50W amp will produce similar levels to an expensive one.
For some fun, try listening to music whilst your oscilloscope is on the speaker terminals. BTW, say, 50W of average music power often makes for some quite loud listening.
ak_47_boy, perhaps you could fit a KT66 in there.
This Sunday we were playing music on a 50 watt per channel amp at clipping point for several hours . The signals ( monitored on a scope ) clipped slightly on loud transients .
After about four hours my ears felt uncomfortable. The music was clean and it did sound very good.
Speakers were 88db/watt/m and the room is about 15x22x12H feet.
So 50 watts per channel is pretty loud.
After about four hours my ears felt uncomfortable. The music was clean and it did sound very good.
Speakers were 88db/watt/m and the room is about 15x22x12H feet.
So 50 watts per channel is pretty loud.
Is SE better than PP for hf? What tube should i use for the hf? I figured out all the tubes that there are lots of scematics for.
EL38, EL34, EL84, 6B4G, PL519, 807, 6V6, 6l6, PX4, PX25, kt66, 6as7g, 2a3, 300b, kt88.
The PX's are a maby there arn't many scematics around but i found a place that sells the tubes. I read they are good.
So what should i use for lf, mid, & lf? I want 50wpc for low and 30wpc mid and 10wpc high.
Also does anyone have any 3way xover scematics useing tubes but no gain?
thanks
EL38, EL34, EL84, 6B4G, PL519, 807, 6V6, 6l6, PX4, PX25, kt66, 6as7g, 2a3, 300b, kt88.
The PX's are a maby there arn't many scematics around but i found a place that sells the tubes. I read they are good.
So what should i use for lf, mid, & lf? I want 50wpc for low and 30wpc mid and 10wpc high.
Also does anyone have any 3way xover scematics useing tubes but no gain?
thanks
ak_47_boy said:
All shown here: http://www.tubecad.com/articles_2001/Tube-Based_Crossovers/Tube-Based_Crossovers.pdf
Sheldon
Does this mean that the other posts were of no use at all ..... a waste of time for the person who posted a reply and for you for reading it ?
I always like to read all posts even if they wander a bit from the original question as there is ALWAYS a lot to learn from others .
So everyone should be encouraged to post ..... even if it is not an 'exact' reply .
I trust you 'are' having fun , like most of the other members on this forum!
Cheers.
ashok said:
Don't get me wrong, every post in this tread has been quite informative. I have read this whole thread start to finish multiple times.
I just would like to hear a few people opinions that have listened to many tubes because i have not. This is the only question i realy have left right now and its a tough question. The project could be doomed from the start if i base everything around the wrong tube.
I don't think there is a " this is the best tube" or " mode of operation " for your need. SE and PP can sound different to different people.
However , usually ( most) SE circuits are non feedback and most push pull (PP) circuits use global negative feedback.
SE also produces very low power and PP can produce the max the tubes can handle. So if you want more power you must use PP.
SE always works best with very high efficiency speakers unless you listen at very low volume levels.
I would think that you need PP for both your mid and tweeter and a ss amp for the bass . A good ss stage would probably have better control over the woofer than an equivalent tube PP stage. The tube PP stage also being far more expensive to build.
I think the power ratings could be 20 + 20 + 75 watts (SS). Lots of circuits for that. The 20 watters can be easily made with EL84's ( multiple tubes) or EL34's ( old favourites) or 6L6 a and possibly 807 (?). A 75 watt tube amp will be far more expensive than a 75 watt ss amp.
How much can you depend on someone elses's opinion of a tube.........? Well check out the 300B tube. You have plenty of people who love it and plenty who don't. They are all correct . It just depends on what your ear likes best ! To discover that for yourself pick a tube and build the amp. I'd go for the EL34 tubed amp and ss or even the class D bass amp.
Cheers.
However , usually ( most) SE circuits are non feedback and most push pull (PP) circuits use global negative feedback.
SE also produces very low power and PP can produce the max the tubes can handle. So if you want more power you must use PP.
SE always works best with very high efficiency speakers unless you listen at very low volume levels.
I would think that you need PP for both your mid and tweeter and a ss amp for the bass . A good ss stage would probably have better control over the woofer than an equivalent tube PP stage. The tube PP stage also being far more expensive to build.
I think the power ratings could be 20 + 20 + 75 watts (SS). Lots of circuits for that. The 20 watters can be easily made with EL84's ( multiple tubes) or EL34's ( old favourites) or 6L6 a and possibly 807 (?). A 75 watt tube amp will be far more expensive than a 75 watt ss amp.
How much can you depend on someone elses's opinion of a tube.........? Well check out the 300B tube. You have plenty of people who love it and plenty who don't. They are all correct . It just depends on what your ear likes best ! To discover that for yourself pick a tube and build the amp. I'd go for the EL34 tubed amp and ss or even the class D bass amp.
Cheers.
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