Maybe it's because I haven't tried every amp in the world.... But IMHO, for bass, when individually optimized, tube has no advantage over sand. (mid-high is another story and I love tubes on that, too)
For bass, limited size and ultra high sensitivity just don't come together, period.
I think it depends on what frequency range you define as "bass", but around here, regardless of how you frame the argument someone will disagree.
I saw these at 6moons recently and thought they were cute:
ENHome
Speakers like my NaO and the Orion are capable of about 110dB from the midrange/woofer crossover point up (~120 Hz) with a 60W amp.
I guess I should have told the entire story about how this system came to be... Of course, someone would accuse it of being a Macho ting anyway.
Well, the background is that this small place called Vevring, at the west side of Norway, is in danger of getting a big titanium mine, which will mine away an entire mountain over 40 years, and dump the debris into the fjord, in addition to generating lots of noise (the mine would be just a few 100m from the nearest house). Some folks in Vevring came up with the idea of making an audible protest against this, something like a big trumpet. They contacted an artist, Geir Hjetland, who came in contact with me through a mutual friend. We then set out to design a visually impressive instrument that should look like it could produce lots of sound. So in this context, it is about size, and not so much about quality.
It was intended as a piece of art and an instrument to play Maja Ratkje's composition. This piece will not be played on any other speakers. The horn was not intended as a sound reproducer, and I was surprised how well it worked for reproducing music. And in this context, as an instrument, it is not an absurdly extreme design. An 8 ton chuch organ is considered small...
If I had built this horn for my own use, just to show off, it would be a 'Mine is bigger than yours' kind of macho ting. I didn't. I aided in the design of an instrument used for an environmental protest.
Regards,
Bjørn
This will start looking like Romy's system, not that that is bad. I think the line for the bass isn't such a bad option. It will load the room more smoothly than "point source" monopole bass, averaging out vertical peaks and nulls.
The line is big though and has relatively low WAF. Then again any high efficieny system is going to have pretty low WAF, if their wife is anything like mine, who doesn't want a bunch of hi-fi stuff in the living room.
Sorry, I meant 100W amp. And I add the cavate that I am referring to the midrange/tweeter panel and based on my experience with the Orion I am estimating it to be about the same as the NaO. The Orion is complicated by the need for multi-amps.
Kolbrek - not to worry! Don't let the grumpy few get you down.
What you have done is great. And a lot more fun than most of us are having.
As you said, you mostly built a musical instrument. And for a very good purpose. Hat's off to you!
What tends to get forgotten around here is the title of the forum. diyAudio - not diyUltraHiFi.
What you have done is great. And a lot more fun than most of us are having.
As you said, you mostly built a musical instrument. And for a very good purpose. Hat's off to you!
What tends to get forgotten around here is the title of the forum. diyAudio - not diyUltraHiFi.
Okay, here's a quick stab at a baseline in Hornresp:
Driver: GPA 515-8G
Cabinet volume: 4.3 cu. ft.
External Cabinet dimensions: 24" wide x 24" tall x 20" deep
Slot Port: 22" wide x 1.4" tall x 6" long
+/- 2dB from ~70Hz to 500Hz (top end likely more extended in real world)
~104dB/2.83v
Attachments
It's 'raw' enough for comparison purposes for the BW under discussion. As for the rest, I just posted some plots I have and make no claims otherwise about them. Note there's Freddy's I linked to in a more recent post to consider as a better one for comparison.
GM
I haven't followed this thread before I posted some response plots LO wanted, but if this is where it's headed, buying/building under license John Tucker's/Jeff Markwart's Exemplar bass bin as outlined in Sound Practices #9 seems the goal, then it's just a matter of determining a 'sub' system solution.
FWIW, if using an expo with the 515 rather than the Exemplar's tractrix, then whacking off an 825/828 to a ~75 L net rear chamber tuned to ~75 Hz worked well for me with a 500 Hz XO, so converting it to round with a well damped mouth might audibly improve it enough to be worth the extra effort. Mine were dual stacked for local PA apps to create a more portable/compact '50s era A6, so subtle SQ improvements weren't a concern.
GM
Last edited:
Here is an idea for midbass region. In the thread it is mentioned that the horn is roughly 4' in length and a bit more than 2' in diameter.
New Cogent 100Hz Conical Horn
In other threads it is mentioned that Jonathan Weiss ended up using an 8" cone driver on a similar horn in his AC2s. That is probably the angle I would look at if persuing due to economics.
New Cogent 100Hz Conical Horn
In other threads it is mentioned that Jonathan Weiss ended up using an 8" cone driver on a similar horn in his AC2s. That is probably the angle I would look at if persuing due to economics.
An externally hosted image should be here but it was not working when we last tested it.
Its a dilemma - at least *all* options are clear.
Though I can see you're heading towards the monopole camp more and more, I'd like to bring up again the dipole alternative.
Arrange four high eff. 15" below your Azura horn in a diamond array and use the shunt trick in two steps to balance roll off.
http://www.diyaudio.com/forums/multi-way/90804-large-midrange-ob-scott-g-9.html#post1955645
Compact, easy load (best done with an active mix of your valve-amp plus a stereo ss), simple to build – relatively cheap – plenty of headroom and sensitivity -and not such an ugly looking and boxy sounding disco-Murks (excuse me Bill) you seem to be seriously thinking about right now....
I know you love the SPL gain by floor mirroring – forget – sound will improve *not* to use it
Check out my suggestion with SL's spreadsheet and you easily should see it *is* an option
########
Bjorn you built a great assembly for a great reason!
The second video which seemed to be the record of the whole composition sadly ended after a short time every time I tried.
Not been right up there but relatively close to – its a great landscape of inspiring naturalness and devoutly silence worth to have our protection.
Michael
Last edited:
Lynn, I don't think this has been posted here yet, but I thought you might be interested, especially the mid bass application.
The Octagon
I had Khorns for many years. Once I started working on the limitations, bit by bit, I had replaced every part of them and they went into storage. Whilst they had their faults, they were fun.
The Octagon
I had Khorns for many years. Once I started working on the limitations, bit by bit, I had replaced every part of them and they went into storage. Whilst they had their faults, they were fun.
In a real room, my previous model's 2-pi space sim probably isn't the full story. Here's how it looks in 1-pi space with a bit more cabinet volume and lower tuning. Adds another half octave to the bottom and raises efficiency. In a corner (0.5-pi), it would go deeper still.
Attachments
Last edited:
Yeah, you don't realize how big that is just looking at the pics until you read that those small-looking drivers in 4 columns of 3 are 15" woofers.
The folks at decware have developed a couple of versions based on the Jensen Imperials for subwoofer and woofer use. They will see the plans and could be another hi efficency solution.
DECWARE IMPERIAL S.O.
DECWARE IMPERIAL S.O.
An externally hosted image should be here but it was not working when we last tested it.
Last edited:
You possibly should carry out a prove of concept – will take you a day or two maximum
Take four of the woofers you have laying around – cut a baffle not bigger than needed to arrange them in a square – wire two and two (diagonale ones) in parallel and the twins in series – calculate a suitable capacitor and shunt one of the couples.
Now give it a listen with your valve amp regarding SPL and do measurements (polars preferably).
In case you haven’t used 15” woofers go to SL’s SPL-max spreadsheet and correct with the figures there.
Pretty confident you don’t have to look for alternatives.
Michael
Thanks, GM, for posting the Hornresp sims, much appreciated. I'll be contacting Bjorn Kolbrek (the co-developer of the AH425 horn, along with Martin Seddon) and trying various ideas for bass/vented horns and curved horns in the 70~100 Hz to 800 Hz region. Anything below that is natural subwoofer territory, and the region where Class D transistor amplification performs at its best.
I've listened to eXemplars in the local area and in the Northwest, and they weren't for me - I heard very little below 150 Hz, much less 60 Hz. Conversely, the Blue Thunders in Zurich were very well-balanced through 50 Hz, and there was no audible transition between the short horn and the (forward-facing) vents - so it can be done. The big problem appears to be getting the transition region correct - and taking steps to avoid panel resonances if the rear box has large panel areas.
I'm wondering if the choice of bass horn profile isn't making the transition to the broad Helmholtz resonance of the box more difficult - a sharp cutoff is the last thing you'd want in this application. If I understand this stuff correctly, the desired horn profiles that would provide a gradual rolloff would be straight conicals, quadratic-throat conicals, high-T-ratio (above 5) JMMLC profiles, or Dr. Geddes' OS. Sure, low diffraction would be nice, but first, you have to get the in-room response halfway flat. Booms and thuds, or octave-wide holes, do not sound very good (of course, this is a description of the sound in many rooms at the RMAF and the CES).
The one thing that gives me pause about a vented shorthorn is the how much the room is going to affect the transition region - the 120~250 Hz region is where typical listening rooms are at their worst. The vents are small in relation to the box frequency, so they are omnidirectional. The polar behavior of the horn through and below the cutoff region is more complex. Something as apparently minor as the choice of vent location might make a big difference in the listening room. All of my instincts tell me that keeping the vent exits and the horn mouth fairly close together might be a good idea, so differential room-loading effects wouldn't throw off the system tuning.
Last edited:
If you haven't already seen it, our friend "Freddyi" has made a wonderful series of postings from the pages of Audio League Reports magazine, covering the years 1954 and onward. Reading the show report of the 1955 Audio Fair is hilarious - here we are, more than fifty years later, and exhibitors are still chasing away audiences with clipped, distorted amplifiers and industrial shop-floor sound levels.
1954, Volume 1, Number 3, Heath WM4 Amplifier
1955, Volume 1, Number 8, Tonearms
1955, Volume 1, Number 9, Karlson and REL Precedent FM Tuner
1955, Volume 1, Number 10, G.A. Briggs Carnegie Hall Demo, National Catenoid Horn, and a Response to Consumers Union on Cartridge Testing
1956, Volume 1, Number 11, Audio Fair Show Report, AR1 and JansZen 130
Thanks again, Freddyi, for doing this massive job of scanning and reposting!!! Great job!!!
1954, Volume 1, Number 3, Heath WM4 Amplifier
1955, Volume 1, Number 8, Tonearms
1955, Volume 1, Number 9, Karlson and REL Precedent FM Tuner
1955, Volume 1, Number 10, G.A. Briggs Carnegie Hall Demo, National Catenoid Horn, and a Response to Consumers Union on Cartridge Testing
1956, Volume 1, Number 11, Audio Fair Show Report, AR1 and JansZen 130
Thanks again, Freddyi, for doing this massive job of scanning and reposting!!! Great job!!!
Last edited: