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As the very happy new owner of a Shindo Cortese 10 watt SET amp I'm seeking the expertise of this group on speaker compatibility. I'm not trying to compare this amp to the previous more powerful SS amps I've used with my 87db Sehring 602 speakers, it is much better. My question is am I getting the best out of my amp with 87db speakers? My room isn't particularly large and I'm in a condo so low volume listening is more important than how loud it will go. Thanks for your help.
Follow Ups:
I'm considering the Cortese to pair with Verity Audio Fidelio Encore speakers. These are 89db efficient with an apparently, pretty flat 6 ohm nominal impedence. They sound excellent at the showroom, but was hoping to get some guidance from this group. I really don't listen too loudly. My room is 20x17 with an asymetrical vaulted ceiling. The room volume calculates to about 3200 cu ft and I'd describe the room as moderately lively.I've listened to the Synhonia monblocks (40W) and they are perfect in everyway and so dynamic, but $$$ too rich for my blood. Those monblocks may be the best I've every heard. The Cortese use the same tube in a single ended pentode configuration and sounds great too with similar character, but obviously limited power.
Comments?
You own the amp and speakers. Listen to them. If your happy, pour your self a glass of Balvenie Double Wood, sit down and relax to music.If you still want to scratch the "speaker itch", bring your old SS amp and your new tube amp to a friend’s house or a real "Audio" dealer and listen there. Don't let the watts bother you. Power amps watts have been abused by marketeers almost as much as blondes have sitting on cars.
Depending on the source you quote, to double the apparent loudness of music takes 8 - 10 dB more power.
3 dB is 2X the power, 10 dB is 10X the power. 20 dB is 100X the power. 30 dB is 1000x the power.Example:
In my office at night I used to listen with a 1/4W tube headphone amp driving my 93 dB/W speakers which would be about 87 dB max output. With the doors closed, this doesn't bother Mrs. Volt trying to sleep two rooms over and I’m happy with the volume.During the day, I've play with a 1W class A amp (8W peak) that goes as loud as I want on the same speakers (93 dB). Monitoring the output of the 1W amp playing music, I normally don’t exceed 2W peak, which is 1W class A
Play safe and play longer! Don't be an "OUCH!" casualty.
Unplug it, discharge it and measure it (twice) before you touch it.. . .Oh!. . .Remember: Modifying things voids their warranty.
The sensitivity is only one third of the equation, the other issues are impedance (over the entire response spectrum) and output impedance of the amp/damping factor. If you can view an impedance measurement, see if the speaker maintains a relatively constant impedance or encounters severe dips at various frequencies.My Merlin TSM is only 87db efficient, but with its outboard Zobel network, presents a nearly constant 6 ohm impedanced across the frequency spectrum. Partnering with the 15wpc Wavac MD-811, is sounded as good if not better than the VAC Avatar running in 27 wpc triode.
Thanks to everyone for sharing their experience and knowledge. For now I will enjoy what I have and start to explore what high efficiency speaker options are out there.
you will not hear the most and best of what your SET can do with low efficiency speakers.They are just too massive and SLOW.
High Eff speakers will recreate more low level detail, scale and nuanced musical texture, and in a much more dimensional way....IMO.
This doesn't mean you can't enjoy an improvement with this setup, just that it can actually get even better. :)
You should try it.
...Derek Walton who has the step by step primer on the DIY JE Labs 300b SET mono block plans had on his website that he ran his 87dB efficient speakers with his 8 wpc 300B mono block amps. I would never do this myself. I try to inform folks that people who jump into SET with the wrong speakers can end up hating it and wind up with a bad experience for all SET amplifiers. Find some good speakers to match up with your new amps. If you buy used speakers to save money it is hard to beat Klipsch Cornwall, Altec duplex, Valencia, Model 19 and many other very efficient speakers. All save the Valencia can be had used for under $1K. Have fun as you learn. Reading in the archives here you can find lots of speakers that are easy to drive with SET amps. I used to let friends hear my 2-way 6' tall horns with twin 15" woofer bass bins that used to be powered with a single pair of 1.7 wpc amps when they came over. The amps were the Welborne 45 DRD tube rectified mono blocks that easily powered those 100dB plus efficient speakers. I now biamplify with a active crossover with 45 and 300B SET mono amps. The 45 vacuum tube is one of my favorites for very realistic sounding vocals and midrange heard through my large horns. John
You will get a taste of set.But sets real openness and what it can really do will not emerge so much.
We kind of have to accept the notion that what we are looking for is really tied to as high an effeciency speaker as we can get.
Not too long ago, I passed up on those highly tooted and somewhat remarkable field-coil speakers because i think they were only up to 95 db effeciency. I certainly could have enjoyed them for what they do: I remember the speakers for remarkable nuance, clarity and detail. The direction of the qualities of openness, realness and presence is way more important to me, so I am pretty well tied to the notion of high effeciency it seems.
When it's not so high effeciency and also two-way or three way speakers, I think it's more in the direction of other audio gear and less towards something maybe quite unique to set or its potential.
It has been my observation that High Efficiency speakers sound more natural and musical - as a general observation, much less with a low power tube amp.If you're getting by OK, my suggestion is to take your time, hang around the high efficiency forum, listen to what you are able to do so, and start laying the groundwork to move to high efficiency under the terms that are best for you.
This is exactly my setup and I find it quite adequate. I listen to a lot of orchestral music among other things, and dynamics are not compromised in any way. At roughly 1 W/ch, SPL in my room is the same as in the middle of a concert hall, and I don't want it to be louder than that.Speaker sensitivity, IMO, is not as important as the ability of the speaker to retreive fine detail at low levels. Many 85-87 dB speakers just lack this ability. If your speakers do not compromise sound quality at low and very low levels, they are perfectly fine with a low power amp.
I've been a SET devotee for lo these past 10 years. One of the most magical combinations to pass thru my listening room were Loesch triple 2A3 monoblocks (about 10.5 watts) into Spica TC-50's (about 86dB efficient) in a large room. I've moved on into the Lowther camp, which is a whole different trip. But note use of the term "different" as opposed to "better." Which is not to say I'd wanna return--Lowthers have a funny way of making other speakers sound bland--but which is to say, my Loesch and Spica days were wonderful while they lasted. (A listening room flood took out my dearly departed Loesch amps.) Give your combo an honest chance . . . you might well find the same wonderment.
There's really no problem using a low powered amplifier on inefficient speakers as long as your room is not too large or that you don't subscribe to high sound pressure levels(reasonable expectations). I'm currently using my EML 520 tube SET(22 watts class A)on a pair of Spendors that are 86 dB. No problem here!
It's not likely the Sehring's were designed with low wattage single ended amps in mind, or even a chance consideration.If you only listen to acoustic, folk, chamber, a capella, sedate jazz trios, etc. at low volumes, then you may find it a satisfying match.
But, let's look at this from a dB/power perspective. The 602's are rated at 86dB/1W. It takes twice as much power for each 3dB increase. So, 89dB/2W, 92dB/4W, 95dB/8W, 98dB/16W, 101/32W, 104/64W.
Complex music like orchestral can have short term dynamics bursts(the difference between the softest and loudest sounds in a recording) that are 14-20dB above the average level(LP's). That would push the amp deep into distortion and compression territory.
The Shindo is a legendary SET, but if it was me, I would not spend that much money on a less than ideal match. To really let that amp sing to it's full potential(which is superb), I would get speakers above 94dB efficiency, above 96dB would be even better.
To let your Sehring's sound their best with tubes, look for high power SET's like KR Audio's .
nt
nt
Doubling or halving VOLTAGE into the same load is a change in power of 6dB, but that's because current, too, doubles or halves.
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Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
on decibels and power in Wikipedia.One quotation from that article:
"A practical example
A fictional 2 way speaker (A box with separate driver for high("Treble") and low("Bass") ) has the following specs:High driver: 92 dBSPL @ 1W @ 1m. A Low driver: 86 dBSPL @ 1W @ 1m.
Now if we want to match the output of the two speakers so the sound is "equally loud" we need to do the following:
Get the difference between the two by subtracting the sensitivity:
Difference in sensitivity = A-B
= 92 dBSPL - 86 dBSPL
= 6 dBSPLAs we concluded earlier this 6dB difference requires that we double the power delivered to the low driver. Since a doubling in [power] relates to 3 dB, we need to adjust the cross-over unit in this system so that the [gain] of the Low signal is 3dB more than the Highs. If there is no crossover you can always adjust the Amplifier's output to be 3dB more."
Sorry, you can't use Wikipedia as proof text. It's user driven. I mean I could go there right now and make up anything I want and post it. It's true that over time someone will correct it but.......For something more definitive read Tremaine, page 1635, fig #25-105A. "DB versus power in Watts"
This graph shows if 1 watt is 30DB above reference then 10 watts is 40DB above reference. 2 watts is 33DB, 4 watts is 36DB and 8 watts is 39DB.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Just because it is written somewhere does not mean it's true. Look at the foolishness supported by a few authors like Crowhurst on the PP loading...:)if you can't get there from first principles( as in Tremaine ), one should consider conducting more research.
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
...of a ratio of 2 different amounts of power. A deciBel (that's 10 times a Bel in metric terminology) is 10 times the base-10 log of the ratio.The base-10 log of 2 is 0.301. Ten times that is 3.01, and that round to 3, so double the power is 3dB.
Do not confuse subjective expressions of twice as loud or half as loud with the very precise definition of deciBel. And as for 6dB, I've read elsewhere that many people require a change of about 10dB before they'll say a loudness is twice or half.
-------------------------------------------------------
Tin-eared audiofool and obsessed landscape fotografer.
http://community.webshots.com/user/jeffreybehr
For amplitude, e.g. voltage and sound pressure difference:XdB=20lg(X/Xo)
For power difference
XdB=10lg(X/Xo)
Hence 3 dB of power increase brings about 6 dB of SPL increase.
http://www.jblpro.com/pub/manuals/pssdm_1.pdf chapter 2http://www.analogrules.com/dbwatts.html good math, nicely explained
http://sound.westhost.com/class-a.htm table #2
http://www.bassbacke.de/hints/bass/cabproperties.htm another power vs.sound pressure chart
http://users.chariot.net.au/~gmarts/amppower.htm "double the power is equivalent to only a 3dB increase in volume! "
The math.
8 ohm speaker with 2.83 vrms is one watt.
2.83/8=.3538amps X 2.83 = 1 watt
with 4 volts rms we have 2 watts
4/8=.5amps X 4 = 2 watts.voltage
XdB=20lg(X/Xo)
4/2.83=1.1434.....log = .150723....X 20 = 3DBpower
XdB=10lg(X/Xo)
2/1=2 log=.301029..... X 10 = 3.01029..... DBTre'
In my opinion, three important pieces of the puzzle are the amplifier's output impedance, the speaker's impedance curve (the actual curve shape rather than the "nominal impedance"), and the speaker's frequency response curve. Also if it's a "4 ohm" speaker, does the amp have 4-ohm taps?SET amplifiers typically have fairly high output impedances (low damping factors). In such cases, the impedance curve of the speaker can modulate the output of the amplifier - i.e. where the impedance curve is up the amp will put out more power, and where it is down the amp will put out less power. Now this isn't necessarily a bad thing - in some cases, it serves to smooth out the frequency response of the loudspeaker.
Given your listening style I think it's quite possible that 87 dB efficient speakers could work well driven by a 10-watt SET on most types of music, but I'd have a hard time making a good long-distance judgment call without knowing the impedance and frequency response information described above.
Of course a more direct solution is to just try it and if it sounds good to you, don't worry about whether or not it's "ideal"!
Well, the setup you describe will go up to about 96 db.If you listen to music at about 88 db usually, you will have peaks at about 100-105 db (depending on the material of course).
So, either you listen at 80 db, or you accept some compression.
Amante
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