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So what are the criteria to make it Hi Eff?

192.73.8.199
Posted on April 4, 2000 at 13:23:27
Edp


 
90db - lots
95db - few
100db - scant
103db - 6 sigma?

How measured? Usual way or Thorsten's way?

Impedance swing/variance limitation? +/- 3 ohm, 1 ohm, not required?

Just think it slightly important so as to not have a duplication of the Speaker Asylum, and lots of questions about putting Merlin VSM-SE Bams with sub 20 watt units as examples of Hi Eff.

For whatever its worth my answers to above would be

Minimum level:
Never less than 90db and should be 93db or higher

How measured:
(Manufacturers specs - 3db) unless an independent measurement is done and readily available. So if they say its 91db, we subtract 3db and get 88db, YER OUTTA HERE!

Impedance:
Tough one, because many amps hooked up to Hi Eff's will be much happier with minimum swings, but what source? Very xover dependent.

 

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Re: So what are the criteria to make it Hi Eff?, posted on April 4, 2000 at 13:55:49
Kurt Strain


 
This is about striving for high efficiency and it's all relative. I think what we're talking about are speakers that are low power compatible for average listening, despite what the specs say. Like I posted earlier, these specs are nearly useless. They need to be put into context with listening room, listener, and amp.

A 90 dB minimonitor is quite efficient at 5' back from the speaker, the equal of a 95 dB horn at 9' back, for example, anechoically. It's like defining "high-end audio", not a well defined term. You just talk about what you want concerning striving for it.


Kurt

 

Naw, then you don't need a special place, posted on April 4, 2000 at 14:13:37
Edp


 
Don't agree about mini-monitors in small rooms as hi eff targets.

My reason is simple, I can and do talk general speaker construction with many DIY'ers and some professionals. The experience of it is becoming less challanging. I am looking for new learning experiences.

Designing, create and measure of both full range and hi-eff (sometimes one in the same, not always) are the new challenges I am looking for. There are other pages to get that info, just was wondering if this was going to be another. It could be, but not by your definition.

 

Re: So what are the criteria to make it Hi Eff?, posted on April 4, 2000 at 14:35:30
Jack G


 
If you're not sure, send the speakers to me, and I'll decide if the are efficient enough.:-)
In fact, even if your sure, send them to me:-)
Jack

 

Re: Naw, then you don't need a special place, posted on April 4, 2000 at 14:48:23
Kurt Strain


 
Well, I originally proposed a horn BBS, but that was too specific for some. Now it's too general? I can't answer for everyone. I'm hoping the emphasis is on learning all about horns and the drivers that work best in them. I think the emphasis here is on ways to achieve high sensitivity, however the solutions come about. One way is by simply moving closer to the speaker of course. But that's only one way. I think this is about finding solutions for low power amplifiers, however it is done. Horn loaded high efficiency drivers go the furthest toward that goal I believe. We can discuss all the trade-offs of how to achieve the ultimate goal of a low distorting highly dynamic full range transducer that needs little power, and any space constraints we might have to deal with. But I can't exclude talking about my minimonitors that work well with 3W amps when this is a viable solution. Other people will probably want to know the cheapest way to get their 2A3 SET to sound right, and that is about the cheapest I know of. But for sure let's get into the details of designs I am not familiar with, like start with my bass horn question above. :-) Thanks.

Kurt

 

Re: So what are the criteria to make it Hi Eff?, posted on April 4, 2000 at 15:12:08
Mike Bates


 
My idea of HIGH efficiency is a speaker that will put out 100 db at one meter with a flea amp. I suppose 94 db/1 watt/meter would qualify with a 2a3 amp. Anything under that (90-93db) is just plain ol' efficient.

Impedence is part of the picture of course. Most horn loaded speakers or specialized HE speakers are normally pretty SET freindly. I prefer to use multiple amps and electronic crossovers, no crossover to drive equals higher efficiency and normally an easier load.

Mike Bates

 

No, your mussle amps are too much, and lets not talk about your hearing, posted on April 5, 2000 at 06:40:41
Edp


 
Thought maybe this was the land of sub 1watters here.

But I do have an old Peerless three way here that has some very decent efficient short horn loaded domed midrange and tweeters. Um Um, just the thing for shrill runs of Procol Harum and Yes! Eeeh Yoow!

 

Re: So what are the criteria to make it Hi Eff?, posted on April 5, 2000 at 07:56:15
Tom Brennan


 
To me high efficiency starts in the upper 90s, things like speakers using direct radiating woofers with horn uppers; Klipsch Hereseys, Altec Valencias, Altec Duplexes, JBL L-200s and such. That would be the lower end of high efficiency, with basshorns or multiple DR woofers we get up in the 104 (Khorn, LaScala) and up region. Many audiophile DRs that are passed off as high efficiency are better described as "not so low" efficiency.

 

Re: So what are the criteria to make it Hi Eff?, posted on April 5, 2000 at 11:06:10
Thorsten


 
Hi all,

I'd say let's put this in perspective. With a usual listening Distance of 3m we have about 9db overall loss, about 4db we get back by using Stereo, so at our listening position we have +5db against the 1m Sensitivity.

Now, a classical Orchestra for a good seat will produce 96db, we'd like around 10db headroom with that, so we need 96db at the listening position from a Stereo pair for 1W if we consider a 300B SE Amp "par for the course".

With the additional 5db loss to compensate we are in >100db/W/m territory and I would insist on Watt's instead of 2.83V and preferably measured with pink and white noise. I have found that pink noise SPL measurements give a good indication of how difficult the speaker is to drive.

So, > 100db of SPL at 1m Distance for 1 electrical Watt with pink noise qualifies as tru High Effciency, I'm happy to grant a +/-3db variation on that so Phil can stay with his inefficient CAR T-1's ;-)

So then, my verdict High efficiency starts around 97db and up.... The more the better. Did I ever mention the Community RS880?

Two hornloaded 15" Woofers, one 4" throat and 8" Diaphragm/Voicecoil Compression Driver plus Tweeters (piezo no less). A REAL 108db/W/m Box (not db/2.83V) with a cool 800W RMS Powerhandling and only around 3db compression for that. That is 135db/1m full power from a fairly modest Box, if limited to the 100Hz and upwards range. These combined exceptionally well with the Servodrive Bass-Tech 7, probably the worlds most awesome subwoofer....

NOW THAT is HIGH effciency....

 

Re: Naw, then you don't need a special place, posted on April 5, 2000 at 11:53:31
Cam


 
Kurt -

I agree wholeheartedly with you. I find this new forum very welcome, since I continually find myself having to scour the "normal" speaker asylum for posts on high-efficiency stuff.

And I agree on mini-monitors. My 2A3 SE amps are amazing with a certain little Sonographe 2-way rated at about 87dB/W, and I'd like to get more of that sound in a small higher-efficiency monitor that I can sit close to (Focal or Audax midwoofs without inductor?).

Thanks for creating this forum, and I wish the best for it.

Cam

 

only one requirement necessary - the horn, posted on April 5, 2000 at 13:41:31
Klipschead


 
an end to unnecessary controversy...

Dean,

 

Re: only one requirement necessary - the horn, posted on April 5, 2000 at 14:56:51
Mike Bates


 
I wish I could find a used pair of these for my 15's! They're Meyer sound Exponential Horns used in the late 60's early 70's. The small ones are 4 foot and the big ones are 8'.

 

Are you sure those aren't Avantgarde's latest proto subs? <nt>, posted on April 5, 2000 at 15:48:37
Kurt Strain


 

 

sweet picture !!! but low waf factor!!!, posted on April 5, 2000 at 16:10:36
jon B


 
:-)

 

Re: only one requirement necessary - the horn, posted on April 6, 2000 at 03:31:13
Thorsten


 
Hi there,

I don't think a Horn is needed. I get 101db/W/m (not 2.83V/m, but real Electrical Watts) using pink noise (> 104db/W/m using White Noise) with a lowend (in room) down to < 30Hz. No horns in sight.

Later Thorsten

 

There are horns that don't have 94db and directs that have 101db, posted on April 6, 2000 at 07:20:35
Edp


 
so the controversy still reins.

 

Please name a direct radiating design with 101db/1m/1 watt, posted on April 6, 2000 at 07:28:59
Klipschead


 
!

 

are your numbers really valid?, posted on April 6, 2000 at 07:35:26
Klipschead


 
I mean - isn't the sensitivity of a speaker measured in an anchoic chamber - or some other controlled environment - without the additional gain that the room gives you?

Dean,

 

ok - lets try it this way..., posted on April 6, 2000 at 07:43:44
Klipschead


 
any system that can be driven to uncomfortable volume levels with 20 watts of amplification?

this is harder than i thought it would be...

Dean,

 

Re: Please name a direct radiating design with 101db/1m/1 watt, posted on April 6, 2000 at 08:29:28
Mike Bates


 
My DIY TAD's are actually going to be right about there when I'm done. I'm using two 1601a woofers a side, when ran in parallel,in a single box will be around 103 db efficient. For mid-bass low-mid I'm using TAD 1201h 16 ohm 12" drivers. Without a horn they are 100 db efficient I plan on putting them in a 100 hz Edgar tractrix horns when I get them, from 650 cycles up a 4002 TAD compression driver in an Edgar round tractrix horns, around 114 db efficient with the horns. I am using 4 JBL 2235's for the bottom octave, around 99 db efficient when used as a pair. This system is quad amped with active crossovers. My expermental boxes are not in the least bit compressed and sound better than any system I've ever heard!

Mike Bates

 

How many of us have anechoic listening rooms?, posted on April 6, 2000 at 08:44:50
1Joe2Many


 
8^)!

 

Re: are your numbers really valid?, posted on April 6, 2000 at 09:25:28
Thorsten


 
Hi there,

I personally think they are valid. What they do is to give us a good idea of the real-world drive requirements.

I have measured so far, using EXACTLY the same methode a range of Speakers. These included:

Wilson Audio Watt/Puppies (rated at 93db/2.83V/1m, measured 93.5db pink) same BTW for my Copies. Note that these are difficult load 4 ohm Speakers.

Beauhorn Virtuoso (rated at 106db/2.83V/1m, measured 103db pink), note that these are very easy load 8 Ohm Speakers (around 11 Ohm Average).

Hoerning Perikles (rated at 96db/2.83V/1m, measured 96.5db pink), note that these are moderatly easy to drive 4 Ohm Speakers.

Orchid Audio PLL1 (rated at 89db/2.83V/1m, measured 86.5db pink), note that is a very conventional, timecoherent 6-Way Speaker, moderatly easy to drive 4 Ohm Load.

Epos ES-12 (rated at 88db/2.83V/1m, measured 87db pink), note that is a rather easy load 8-Ohm Speaker.

Looking purely at the results and at my experiences with all these speakers in the context of low powered Valve Amplifiers I can say that we have there a really good indication how difficult to drive each of these speakers are.

Measurements where taken with a modified Radio-Shack SPL Meter that had been calibrated against a professional unit from the "anti-noise" squad.... Source was allways the pink noise track from the Stereophile test CD, recnt additions are white noise measurements using my PC based measurement setup as source.

So I feel that yes, we can consider the measurements realistic and comprehensive. If I wanted to go spec mongering (as many manufacturers do) I could probably quite safely claim 107 db or more as sensitivity.... So giving the 101db/2.83V/1m in room, pink noise rating seems exceedingly fair to me. And by keeping conditions equal the measurements become comparable.

Later T

 

The Thunderstone Audio "Magnificat"....., posted on April 6, 2000 at 09:32:56
Thorsten


 
Hi there,

The Details as on my "Systems" page (Photo's to come soon).

"I'm using 140 Liter vented Boxes with one each of Goodmans Axiom 80 and Goodmans Axiom 201 vintage Fullrange Drivers. The resulting Speaker manages 30Hz in room response, over 101db/W/m sensitivity and an extremely undemanding 8 Ohm load. Excellent!"

To add, the Speakers are actually apperiodic cabinets made from Solid Pine and Spruce with extensive Martix Style bracing and a 4mm skin of very hard plywood (both for sound and looks). They are loosely modeled on the Rehdeko RK175, but use much better Drivers (Goodmans Axiom 80 10" Fullrange and a Goodmans Axiom 201 as additional Woofer, whizzer removed).

Both Drivers are nominally 15 Ohm, I have measured in open Air (no enclosure, outside - hence pseudo-anaechonic) on white noise the Axiom 201 at 101db/W/m (or 95db/2.83V/m) and the Axiom 80 alone at 109db/W/m (it's quite tipped up in the Midrange, hence the bigh jump) or 103db/2.83V/m.

Oh yes, both drivers are sadly now out of production since the Mid 70's....

Later T

 

I wish I had your know-how..., posted on April 6, 2000 at 09:37:30
Klipschead


 
that sounds so absolutely cool. I can only imagine how sweet thats going to sound. Your room must be pretty big. I hope it goes well for you.

good luck and crank 'em up!

Dean,

 

seems I'm going to get quite an education here..., posted on April 6, 2000 at 09:40:41
Klipschead


 
Please be patient with me. My learning curve is huge right now. I feel like Alice in Wonderland.

Dean,

 

Re: I wish I had your know-how..., posted on April 6, 2000 at 10:06:58
Mike Bates


 
The best know how I have is finding a reasonable price for the drivers! I have around $2500.00 in them including the drivers and horns. The retail for new ones is over $8000.00.. I'm using Bassbox software for the cabinets. With the quality of these drivers the most important thing is matching them to the proper box. Using the inexpensive but high quality Marchand crossovers makes the crossovers simple. I'm just trying different crossover points, listening, and measuring. I've been buying planers. electrostats, and conventional speakers for years and have owned some pretty good ones, this is my own all out assault at building something better. I've built quite a few speakers over the years but nothing like these... I seem to get greater satisfaction have a lot more fun building and tweeking my own. : - )

Mike Bates

 

Re: Please name a direct radiating design with 101db/1m/1 watt, posted on April 6, 2000 at 20:41:18
Jon Risch


 
I design them all the time. Pro sound speakers run about 96 dB to 102 and up. A 15" woofer with 100 dB sensitivity in a vented box is nothing to sneeze at! How about 6 1/2" midbass unit or a 10" stamped frame woofer at a real world 97 dB ?

Guess what happens when THESE babies get put in a horn!

Most of the highs are covered by compression drivers, which will hit an average of about 110 dB on a typical 90 by 40 degree CD horn.

Audax is supposed to be bringing out a 100 dB direct radiator dome tweeter soon, should be interesting. I'll let you guys know what they sound like once I get samples and check them out.

Jon Risch

 

Absolutely mind boggling..., posted on April 7, 2000 at 06:38:07
Klipschead


 
This is really the true way to hi-end. I feel like I just discovered the Holy Grail.

Dean,

 

Infinity SM-150, posted on April 7, 2000 at 07:25:28
GCM


 
GCM

 

Whole Earth Catalog, posted on April 11, 2000 at 04:44:57
Jussi


 
These remind me of the ultimate speaker review, in the Last
Whole Earth Catalog (which I have here someplace, just need to
um, locate it), speakers looked much like these (maybe were?),
and the review went something like 'sent on a truck, for the
times when you just want to shake') I'll try to find the
article.

They were my dream speakers (and surely would have fit into
my bedroom or dorm room, especially in a Hafler quad config!)

 

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