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speaker that can be driven by tube amp

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how to know which speaker can be driven by tube amp?

browsing web, looking at 300b amplifier kit, they only have 9w per channel, would spendor s53/5 speakers (recommended driven by 100watt+ amp and Sensitivity for 1W @ 1m is 84dB) being driven by the 9wpc? how to determine which speaker can be driven by 9wpc? look at the sensitivity?

or the speaker need impedance compensation circuit required?

aware that speaker can be damage when driven by smaller than recommended wattage, is that a risk say use 300b amp to drive them? or have to listen at not too loud volume?
 
Yes you are correct to look at the sensitivity of a speaker. Spendor says the S5e is rated for 87dB. Thats a bit low for a 300b amp. I use a pair of Infinity Qe speakers rated for 89dB on a 15 watt 845 amp. I'm not sure how using too little power can damage a speaker? :confused:
 
Speaker choices

Myself now diving into tubes I have begun the search also for the 'ideal' speaker to be driven with a low power tube-amp.
My old DIY towers blowing out the surrounds has now made my move up manditory.
I would put sensitivity at the top of the list given that I do indeed want "Rock concert" SPL levels (Appx. 115 Db). Impedence response engineering is by no means an easy task to take on and I believe the net results will not be worth the effort.
The speakers I'm leaning towards are the Cerwin Vegas or the Klipsch brands..both offer very high SPL levels with the Klipsch being more accurate but pricier.
The Chorus and Chorus II line of Klipsch, now out of production for a while offer a good value for the tube-driven crowd...still too expensive for me sooo.I will be going with the Cerwin Vega E715 at an SPL of 102 Db @ 1M..out of production just recently at half the price of the Klipschs, not the greatest of accuracy nor imaging but I'm sure they will be fine for my application.
_________________________________________Rick..........
 
89 Db??

YUkkk..
89 Db is way too low for tube stuff!
Do the math!!
89 Db @ 1W
92 Db @ 2W
95 Db @ 4W
98 Db @ 4W
101 Db @ 8W
104 Db @ 16W
Your system is already maxed out with only 104 Db! can't even compete with the vacuum cleaner.
Choosing high SPLs is paramount to giving you good transients, dynamic range and available headroom.
Damage to speakers occurs when low power amps hit clipping and when the amp bounces off the power supply rails squaring the signal the amp will "ring" making a very high frequency which the speaker cannot handle.....often times burning up a tweeter.
_________________________________________Rick...........
 
Originally posted by milen007
aware that speaker can be damage when driven by smaller than recommended wattage, is that a risk say use 300b amp to drive them? or have to listen at not too loud volume?

Originally posted by gmilitano
That is nonsense. It that were the case, turning down the volume on ANY amplifier would damage the speaker.

Not entirely nonsense, at least with solid state amplifiers hard clipping brought about by trying to push the amp beyond its capability can over heat the voice coil in some tweeters. With a SET this may be less of a problem given the different overload characteristics but I wouldn't dismiss it out of hand either.

Of course the solution to the problem of finding appropriate speakers is found on the Loudspeaker fora (esp the single driver forum). Make yourself a nice single driver DIY (Open baffle is easiest and IMO best option there) and supplement with a powered sub.

mike
 
Let's apply Joppa's Rule to the situation. The rule states that for "average" listening spaces an amp/speaker combination should be capable of producing at least 102 dB. SPL peaks at a 1 M. distance. Therefore, speakers with an honest 94 dB. sensitivity rating are appropriate in combination with SE 300B amps.

The Spendor speakers mentioned by the thread's originator are unsuitable.
 
mashaffer said:

Not entirely nonsense, at least with solid state amplifiers hard clipping brought about by trying to push the amp beyond its capability can over heat the voice coil in some tweeters. With a SET this may be less of a problem given the different overload characteristics but I wouldn't dismiss it out of hand either.

Speaker damage occurs only one of two ways; mechanical or thermal. Mechanical failure occurs when it is driven beyond its limits. Thermal failure occurs when the voice coil see more power over a period of time than it can handle. In short, too much average power over time is what damages speakers. A speaker will not be damaged thermally if the average power over time is less than the driver can handle.

A 1W amp that is driven into full clipping will not damage a speaker that can handle more than 1W of power. Go ahead, try it for yourself. Get a recording of a fully clipped signal. Turn down the volume and play it. No damage.
 
92dB+ is the way if you want it loud.

Why though, is beyond me. My recording/mastering engineer does not master over 85dB. He meters before every session. There is a reason for not going over that for extended times.

I wondered about his studio the other day, his grand piano can crank out 105dB. That, to me, was painful.
 
Speaker damage occurs only one of two ways; mechanical or thermal. Thermal failure occurs when the voice coil see more power over a period of time than it can handle. In short, too much average power over time is what damages speakers. A speaker will not be damaged thermally if the average power over time is less than the driver can handle.

Yes, this is usually true. However average music has a fairly well known distribution of energy throughout the audio spectrum. There is far more energy (and power) in the bass region than there is in the treble. A well designed, econonical, multi - way speaker system takes this into account.

If you were to examine each individual driver in a 3 way speaker system (lets just assume a 100 watt power rating) you would find the woofer rated to handle the most power since this is where most of the power is in musical material. The woofer in a 100 watt speaker system should be rated for at least 100 watts. The midrange driver would see a smaller amount of energy, and would be rated for a lower power, say 25 watts. This is needed since it would be difficult to design an economical 100 watt midrange driver. The tweeter would see the least energy and it is not unusual to find a 5 or 10 watt tweeter in a 100 watt system. Most tweeters use 1 inch or smaller voice coils that have a very low mass, mechanically and thermally.

Now feed this system with a 200 watt amp operated at or below the 100 watt level, and all should be well, but feed this system with a 50 watt solid state amp that is driven to clipping a lot, and you will lose the tweeter! I have fried enough of them in my younger days to know. Why? A solid state amp driven to clipping can produce a large amount of energy in (or above) the higher end of the audio range. Remember that a square wave contains all of the odd order harmonics, and a heavilly overdriven SS amp can produce considerable energy to 50 KHz and beyond.

Get a recording of a fully clipped signal. Turn down the volume and play it. No damage.

I would believe this, since the recording, and the amp will roll off most of the high frequency content. Play a 10 KHz square wave or true white noise through that 100 watt speaker system at the 25 watt level, and see how long the tweeter lasts.

Many newer solid state amps and most tube amps do a better job of limiting the high frequency energy when overdriven, but there is still plenty of truth to the statement.
 
Tubelab: reasonable anlysis for general discussion, but we're talking an SE300B and a Spendor S 3/5. The amp will not damage the speakers in normal use even if driven into 50% clipping for a sustained period (unlikely).

milen007: as a former mad tube head, I would not partner a 9W amp with less than about a 100dB/W speaker. So three choices: more efficient speaker, AB tube power amp or SS amp.

Personally, I'd not chose any of them.
 
Tubelab: reasonable anlysis for general discussion, but we're talking an SE300B and a Spendor S 3/5. The amp will not damage the speakers in normal use even if driven into 50% clipping for a sustained period (unlikely).

I agree. I merely disagreed with the "nonsense" reply to the statement that an underpowered amp could cause speaker damage. I worked in a stereo shop during the dawn of the SS era and I saw it happen too many times. House branded 20WPC amp, AR speakers, Led Zeppelin cranked to the max....ZAP!

I don't think that there are too many non - feedback tube amps that can zap an adequately rated tweeter since they don't generally clip into square waves.

I would not partner a 9W amp with less than about a 100dB/W speaker.

It all depends on your listening environment, and requirements. My lab / work room / listening room is about 10 feet by 11 feet. I use 87db Yamaha NS-10M near field studio monitors. I have several amps including a 2 WPC 45 amp which does NOT get loud. For most listening I use a 300B amp. If you are sitting in the usual "near field" location, it is plenty loud. The same combination would be useless in a large room however.
 
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room size, speaker sensitivity and music material will definitely be the factors you will have to juggle. Case in point - I once built a regulated 300B amplifier (Loesch SV83 driver) and paired it with a pair of 96dB Adire speakers. On rock music (ie AC/DC), it clipped real fast. It could only hold together if I listened to 'man with a guitar' acoustic music at less than realistic levels. This is with a pretty big listening room to which the Adire speakers weren't well suited for. This combo may have worked better in a more 'monitor'-like environment.

On the other hand, 20Ws is more than enough with my Urei speakers - though I like the overhead of my 60W 6550 amps.
 
Hi everyone,

I was using one of those inexpensive PP kit amps (AE K-502) with KEF iQ3 bookshelf speakers. They're rated 89dB (2.83V/1m) - no idea if this is a honest rating.
The amp is rated 2x8W (I think 2x5W is more realistic) and it clips quite heavily when cranked up fully.
In my apartment where I sit ~3-4m from the speakers this combination was loud enough to make the neighbors complain. Normal listening levels where somewhere around 1/3 to 1/2 of max volume and this was quite loud. I also used the amp at a party at one occasion with speakers rated ~90dB (printed on the label - again I do not know if this is a fair rating). The amp was loud enough to overcome the 3 am noise of ~40 semi-drunk people dancing and chatting with volume settings at ~2/3.
I do not have dB measurements of those speakers done myself but I was surprised we never had to switch to a more powerful amp during the party. How is this possible regarding the comments above?
Are those small K-16, K-502, etc PP amps more powerful than stated?
Maybe the speakers were actually more efficient?!?

Just my 2 cents although I fear I confused more than helped
:xeye:

Martin
 
I'd agree w/ you. I have a 7 watt se amp, and 96db speakers. I never have it turned up over 1/2 way. It's more than loud enough for parties w/ a bunch of loud drunk people. It's in about a 400 square foot room.
I don't think I'd want any more power. It gets painfully loud if I turn it all the ay up, and I can hear it in the yard, over the passing cars on the street.
 
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