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89db Speakers - How Many Watts?

sKiZo

sKiZo

Hates received: 92644 43.20°N 85.50°W
The victims - McIntosh XR16s. I've had them for 30+ years, so I'm kinda sorta attached to them.

- Speakers are rated at 89db

- I like prog rock with lots of bass ... think Porcupine Tree and Genesis. I'll normally listen at moderate (to me @95db peak) listening levels, but it'd be nice to know whatever I get can handle the big boomers ...

- Smallish listening room. Think oversize closet at 600 square feet.
<EDIT> < < ooPs ... That's 600 CUBIC feet ... > > >

Suggestions that won't break the bank? I was just looking at the Yaqin MC10T which seems to jump out of the pack for entry level toobers.

yaquin%20mc10l%20222.jpg


Purty lil thang, ain't it? 52 watts per channel at 8ohm and you don't need a pre, although that would certainly give more flexibility. Only complaints I found were that the original Chinese tubes are borderline average, but ... you can upgrade a bunch rather cheaply with something like the JJ/Tesla KT77 and a couple NOS 6AQ8. Simple plug 'n play tube swap to make the amp sing, and still under $700.

My concern is that 52wpc seems a bit high for paired EL34s ... and I hear tell Chinese amps tend to be overrated. The old Dynaco ST70 uses the same tubes and will do 35w with 70w peaks, but they use different drivers and obviously old school tech to do it. Which brings me back to the original question of how many watts I really need.

Thoughts? Suggestions? Links to threads where this question has already been answered a hundred times? <G>
 
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That is a nice looking amp, I bet you can change a few caps in that bad boy and a
few other things and it will sing! but I know How you feel I've been using a pair
of Celestion 100's speakers a 82db and with the Fisher amp I have it wasn't loud enough,
now I have a pair a Mission 761i at 89db and big difference, Have you looked into
Audionote speakers I think there more than 89db which give you more in the end.

range
 
With speakers of 89 dB/watt/meter and 52 watts on tap you will hit clipping at peaks of 106 dB at clipping. My Stereo 70 dows very well with my 86 dB /watt/meter Phillips.

By the way, I saw a youtube video testing the Stereo 70 for max output vs frequency once and at 20 Hz it only hit about 20~22 watts before clipping. If that power bandwidth is an honest rating (always a question these days even without factoring Chinese variablility) then you should be all right. just keep it reasonable so you don't peak over about 102~103 dB peaks and you should be fine.

Shelly_D

(dB = 10log(Pout)
= 10 * log (52)
= 10 * 1.7
= 17

89 dB + 17 dB = 106 dB)
 
wOw ... numbers, and evarthang!

Gave me an excuse to head on over to the comfy chair and try out a few of the more demanding material.

- PT - Russia on Ice
- Blood, Sweat and Tears - Smiling Phases
- Genesis - Back in NYC
- Bonnie Raitt - Thing Called Love
- Cowboy Junkies - Continental Drift

... and one of my favorite speaker destroyers, the soundtrack from SuckerPunch. Björk - Army of Me is ... intense.

Using my BSR meter, average SPLs based on my average volume setting was around 95db. With short and occasional excursions up to maybe 105db here and there in the listening session. Those were pulling 120wpc+ from my McIntosh MC2205 ... but not sure what that means compared to "tube watts". I would have pushed harder, but hey, it's after midnight here. <G>

Anyway ... short version, the Yaquin might be a borderline choice for me and my level of insanity. It <should> work IF their rated power is accurate AND their amp is able to handle sustained levels that high without melting down.

Read this elsewhere that had me thinking borderline may not be all that bad.

With either tubes or transistors there will be clipping, and with clipping we have gross audible distortion. But, and this is a big but, there is no doubt, the tube amp is going to sound better, especially over extended listening time. The tube amp is the winner. Its soft clipping, more gradual saturation, and quicker recovery rate is less harsh and easier on the ears.
Credit: http://www.parallelhomeaudio.net/TubeAmpSolution.html

My take on that ... clips happen, but a well designed tube amp can minimize the bad. Add to that, the XR16 speakers have very robust protection, and maybe I can get away with it.

PS ... one of my biggest "problems" is gratuitous use of a dbx BoomBox sub synthesizer. That synths an octave below what the pre is actually providing for that gut rocking bottom that sucks huge amounts of power. I turn that off and I can cut the demand in half but ... and that's a big but.
 
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At your listening levels with 89 dB speakers and room size, I'd say 50 watts will probably not cut it..maybe just barely, but it will always be on the edge. 75 or 100 watts would be more comfortable to handle the peaks a bit better.

I think to get that much power out of two EL34s in push pull, they are probably running full pentode, not ultralinear. Full pentode to me sounds a bit more harsh than ultralinear but bass is somewhat tighter. EL34s are kinda soggy in the bass department compared to 6550s or KT88s for example. But EL34s on the other hand sure have a nice midrange that's well matched for the human voice. Cowboy Junkies should sound great..the other stuff...maybe not so much. If you were listening to chamber music or mostly vocals, I'd say go for the EL34s. But for your style music, EL34's don't seem to be the best match, IMO. KT88s or 6550s seem a better choice.
 
sKiZo said:
- Smallish listening room. Think oversize closet at 600 square feet.
Click to expand...

600 square feet is a large room. About the same size as some 1-bedroom apartments. Perhaps you meant 600 cubic feet -- that would definitely qualify as 'small'.

The Yaqins have been tested by someone (don't have the link), who did indeed find that they do not meet their rated output specs. That amp will probably be closer to 30W/ch. But that's plenty for an enclosed 600 cubic foot space.
 
From my point of view, you really never want to reach clipping, not even with tube amps. Put enough power behind the speakers and you simply won't. If you were reaching 105 dB on peaks, then you are very definatly pushing the clipping edge. That tells me you need at least 3 dB more power and I would suggest as much as 6 dB more. Translating that into watts, 100 (+3 dB) to 200 (+6 dB) watts per channel.

Shelly_D
 
By my estimates just 20 wpc (FTC) will deliever 98 db Seated 10' back from the speakers, Placed in a corner + a full 3 db of headroom. Thats pretty loud. At this level the amp is Only Running at 1/2 Power. It will Never Clip, and will have the Reserve Power Required when the Impedance Dips below 8 ohms.

4 Ohm Speaker Loads aren't even a factor if the Tube Amp uses an Output Transformer with a 4 Ohm Tap. In this case you can drive the Amp to near Full power (-1 db) and stay with-in the Amps Safe Operating Range. While it may look like the a Tube Amp with the same power rating can drive a 4 ohm speaker louder than the SS Amp at the -3 db I recomend, it should be noted that a Proper SS Amp delievers at least a 2 db higher SP into 4 ohms vs 8 ohms, that pretty much cancels out the Advantage of Tubes in term of SPL's.

Most of my listening is done in the 80 - 90 db range where just 10 wpc would still provide more power than I would use with 89 db/w speakers. Most people have no idea how little power there listeninig to untill they hook up meters. I often listen with my meters in the 2 wpc range, and by 10 wpc it's darn loud with my 88 db/w speakers.
 
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Sensitivity is not the only consideration, the impedance plot should not have low dips if wanting to use a tube amp...........I couldn't find anything for those speakers.

A lot of tube amps do clip soft, but there are others (still well designed tube amps) that clip hard!

I'm driving (all be it in a small room) a pair of standmounts that are rated at 86db and a nominal 8ohms, but the impedance pretty much doesn't drop below about 7ohms. The amp is a very linear custom AB triode strapped circuit using the transformers from a MC-10L and winged C EL34's for the output (no gnf), so about 20watt per channel.....no complaints. The original amp was AB UL circuit with a lot of global feedback.

BTW, at those listening levels you will be damaging ya' hearing............just saying.

Personally I think you will be fine with a true 20 watts a channel or higher with 89db speakers, the Yaqin would do OK but for a little more $ a Ming Da MC34-A is better made.
http://www.cattylink.com/mc34a.html

Edit: Oh...just to be clear on the impedance side of things, low dips will make a tube amp struggle.
 
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I have 89db speakers and the 60 Watt/channel amp is about right. It will chase you out of the room with Genesis trick of a tail. Low end shakes the chest...... then there is Grover Washington's then and now........ great low end.
 
Hmm...i just read small room..........but 600 SF :scratch2:

For a nice valve amp with grunt, the Ming Da MC34-AB :thmbsp: switchable between UL (75w a channel) and Triode (40w) modes, all point to point construction.
 
My shop speakers are 88 db efficient and they do fine on an amp thats good for about 14 a channel. They are slightly happier at 30 per channel but its not a massive difference.
 
kward said:
At your listening levels with 89 dB speakers and room size, I'd say 50 watts will probably not cut it..maybe just barely, but it will always be on the edge. 75 or 100 watts would be more comfortable to handle the peaks a bit better.

I think to get that much power out of two EL34s in push pull, they are probably running full pentode, not ultralinear.
Click to expand...

My thought was at least 60 watts minimum, 100 watts better.

As for EL34s and 52 watts- the Rogue Cronus (original version) got 55 (real!) watts out of a pair of EL34s. They used a moderately high voltage (probably 500-525v or so), but didn't have to run the tubes that hard (idled at about 35ma per tube or so. They were Ultralinear, and sounded great.

The problem is, that you have to be careful, nowadays, what EL34s you get, to run this way. There's been, sadly, an apparent lapse in quality control on many available modern-production EL34s. Getting them from a responsible, reputable vendor is paramount- you don't want any static from them, if you happen to get a bad one...

This is likely, AFAIK, why Rogue Audio decided to upgrade the Cronus to the Magnum, and started using KT120 tubes (90w/ch). It was easier to justify the extra cost of the KT120 with extra power, and they side-stepped the whole EL34 problem issue...

Regards,
Gordon.
 
of course more power the better, and get rid of the DBX boombox sub, the less
screwing up you signal the better, that may be your problem. Wow I would love to see
what's inside that amp to see the components they used.

tube
 
Not 100 watts unless you entertain with a dance area outside at times. 30 watts min, 50 watts is best.
 
skriefal said:
600 square feet is a large room. About the same size as some 1-bedroom apartments. Perhaps you meant 600 cubic feet -- that would definitely qualify as 'small'.
Click to expand...

Thanx for the heads up on me having my head up ... <G>
Original post corrected ... although the room size had a lot to do with me thinking I could get away with it at 50wpc ...

The Yaqins have been tested by someone (don't have the link), who did indeed find that they do not meet their rated output specs. That amp will probably be closer to 30W/ch. But that's plenty for an enclosed 600 cubic foot space.
Click to expand...

Also points out part of my "problem". The space isn't enclosed. I knocked the back wall out making it open at the back via an arch with another 1200 cubic feet room, so it's more of an "L" off that. Wasn't sure how to count that ...

I agree that historically paired EL34s tend to rate at maybe 35 watts, but that's sustained. I've also seen that they're good to around 60-70 for instantaneous peaks without clipping. Either that or I'm just reading it wrong.

PS ... there's nothing really wrong with my ss MC2205, and that's rated at 200wpc with 400wpc peaks. Fun watching the meters on that bounce to the stops. :yes: It's also known as a "mellow" amp compared to most ss offerings. Just that it's getting long in the tooth and starting to have some old age issues, so it needs bench time. Don't want to rush things, and seems a good time to experiment. I've got several SS receivers in the spare department, but always wanted to try the tube side. What's driving that now is I recently picked up on a Maverick D1+ TubeMagic DAC, and just that one 396A adds an incredible amount of "flavor" to the sound. Makes me wonder what I've been missing all these years.

(Maybe if all I want is the sound, I should be considering a tube buffer?)

OK then ... recommendations in a strong 60-80 wpc that won't break the bank? Or is that even a bit conservative based on my aforementioned tendencies and tastes?
 
datafone said:
BTW, at those listening levels you will be damaging ya' hearing............just saying.
Click to expand...

Huh? What??? <G>

Point taken. But I had the meter set for slow, and it was only at a couple points in the selections that happened. I will admit, playing tracks like Russia on Ice (PT) do keep the amber Warning Will Robinson! lights glowing fairly bright during the crescendOHs ...

Personally I think you will be fine with a true 20 watts a channel or higher with 89db speakers, the Yaqin would do OK but for a little more $ a Ming Da MC34-A is better made.
http://www.cattylink.com/mc34a.html
Click to expand...

Bookmarked the Ming Da ... one I hadn't run into before. The S&H scared me a bit ... $230! Yeowch!!

Here's another one I'd forgotten about ... the VTA ST-120.

ST-120%20front.jpg


Pretty solid fan base, and it gives a good solid 60 wpc with the KT88 tubes. From what I can find, that's a fairly conservative power rating, and I could probably bump it a bit with a higher bias setting? The kit goes for around $1000 +s&h without tubes and plus the soft start and volume control. Do some digging and find a nice set of black bottles for that right off the bat ... Too much too soon? <G>

Hmmmmmm ...
 
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