It reminds me of 15 years ago, when I used micro porous concrete, the one that comes in big white bricks. I mean, I used it for the boxes! Also the sawdust ( you would use a hand saw to make the curves ) mixed with acrylic glue makes sealant .
You can add some light filling in hornresp to stimulate losses, that will reduce the peakiness in the simulated response and make it a bit closer to the end result. And also look at where room gain starts in your room and see how that affects the response in-room. The Dallas is more modern, has more theoretical underpinningband will probably have smoother response, but older enclosures can still be really good.
Best IME to consider based on musical instrument's responses, impact on our hearing, i.e. lower for lower's sake depends on the range of music one prefers and always need to use a separate sub system for HT, any recordings with VLF such as some pipe organ symphonies with up to +30 dB of dynamic headroom = 1 kW - (driver eff., loss over distance) = $$ class A/B amp $$ required otherwise.
https://alexiy.nl/eq_chart/
https://alexiy.nl/eq_chart/ear_sensitivity.htm
I'm very much a musical omnivore, so anything from classical to tech slam goes. Not a high-headroom pipe organ kind of man, though. Main reason why I'm dead set on horns is because of the transients and presence that they repudetly have.
That being said the Duelund does have potential, still. Like Ivo touched on, stuffing does even out the peaks a bit. It's also more efficient by a few percent, and smoothing the dip around 70Hz requires about half the power that an equal boost in the 50Hz region would for the Dallas.
Additionally it seems to be less sensitive to placement, which is relevant since I will most likely be moving places a few more times in my life and not always get to decide how my listening space looks.
Yeah, it's rather tight. ATC is smaller than Sd, which seems to affect the response negatively.
Still, against my better judgement, I'm going to see if I can't tune the Duelund enclosure a bit. It's mesmerizingly space efficient, so if I can finagle the earlier sections to better suit the Corals I'd be chuffed.
'Preaching to the choir' as my Avatar implies! 😉
FWIW, the pioneers taught me to use acoustic solutions for acoustic problems, so not a believer in EQ boosts, only dips, especially down low where driver power handling is ~nil.
I assume so to some greater or lesser extent, though first need to know your tube amp's output impedance (Rs) and preferably using driver measured specs, adjust Qts: (Qts'): (Qts) + any added series resistance (Rs)
For tubes, best to tune to actual Fs to maximize LF gain BW, i.e. equal impedance peaks.
The box only loads the driver to its upper mass corner (Fhm) where T/S theory peters out = 2*Fs/Qts' and its inductance shapes the rest.
Have yet to read MJK's BLH design doc, so no clue how it compares to the pioneer's (Scott?).
Fair point! Much like in music production, subtractive EQ is preferable. Plenty of available SPL, so dropping a high shelf filter @70 to comparatively bring up the lower frequencies a smidge would probably do fine.
With the risk of sounding dumb (as if I haven't already), how do I tell if the horn is accurately tuned to Fs? Seems so many factors play into it. If it means having a smooth response down to Fs I'd have to enlarge the Dallas something fierce to achieve such a feat.
And with "equal impedance peaks" you mean roughly the same size, or spacing?
Going with an RH84, but I've yet to purchase the OT's so impedance has yet to be determined. Corals sit at ~6.6R.
Really nice redrawing of the Duelund horns.
Practical experience from quite some time ago: Quite a lot can be achieved by playing with the stuffing, raw wool worked really well, and playing with how much you use made a difference. I had wonderful results with the Radford STA 15 amplifier, if anybody can remember that one.
Practical experience from quite some time ago: Quite a lot can be achieved by playing with the stuffing, raw wool worked really well, and playing with how much you use made a difference. I had wonderful results with the Radford STA 15 amplifier, if anybody can remember that one.
Thanks! I'll be posting the files once I've given them a proper look, for posterity. Same goes for the Dallas horns.
With any vented alignment it's when the impedance peaks are at equal amplitude (height in ohms), so has to be measured.
Attached is a Coral example in 1pi space and note its impedance changes with the pi space, i.e. normally design/build and allow some tuning flexibility in its final resting place, which of course is done by adjusting the vent; so for a horn this means either shortening the axial length (not normally an option) or shrinking its CSA, i.e. add a phase plug and now you know why many old horns have them and not primarily for polar response as most believe.
edit: please make a Dueland and your variant in Hornresp and export
Ah. In that case it's not even close
Here's yours vs the modified Dallas in 1/pi space. Seems to be tuned to ~68Hz.The Duelund seems to be doing better on the impedance front, coming out to about 54Hz tuning-wise, and the peaks deviate ~25% rather than the ~50% of the modified Dallas. The stock Dallas is looking pretty nice impedance wise, but then the response has that fat 6dB trough around 90Hz... Lotta numbers to consider!
How critical is it that the impedance is fairly consistent? I realize that it matters a fair deal from an electrical standpoint - but provided the peaks aren't absurdly large or mismatched, where does it place on the list of priorities? Since my listening environment is most likely going to vary for the foreseeable future, I'm assuming 1/pi radiation to kind of average things.
Keep in mind that equal peaks is not always the best choice, and impedance peaks will be different.
dave
dave
Assuming it's a SET amp, it will track the impedance, so will follow any peaks, dips and the inductance rise will EQ the horn's HF roll off to the point where you may have to do a bit of impedance correction to flatten it and of course you can somewhat shape its LF response by tuning them to different height peaks, but you're sacrificing precious power handling for the music's fundamentals, so historically design for max acoustic gain and use EQ to shape (preferably the pioneer's $$ variable DF $$).
When is this the case?
Okay -- So a smooth frequency response isn't really the primary goal, but rather the highest possible averaged acoustic gain so that it can be tamed after the fact?
Also, what's variable DF??
Historically, yes and a 'must' with low power, i.e. no different than having little/no Xmax, so only do 'dips'.
Base (bass)/treble tone controls on tube preamps, receivers.
Base (bass)/treble tone controls on tube preamps, receivers.
Ahhh. Gotcha, good to know! On the subject of amps, I was torn between the Zen triode and RH84, but think I'm locking in the Zen. People seem to like it a lot, and I already have most of the necessary tubes.
But -- back on topic. It's been a long round trip, but so far it's looking like the stock Dallas horn is the safest bet. Decent averaged power, most even (and lowest) impedance curve, and the easiest to build.
Going to read up on horns for a bit, so you folks better not suddenly remember some obscure and intriguing horn variant out of the blue and mess up my plans for the weekend
But -- back on topic. It's been a long round trip, but so far it's looking like the stock Dallas horn is the safest bet. Decent averaged power, most even (and lowest) impedance curve, and the easiest to build.
Going to read up on horns for a bit, so you folks better not suddenly remember some obscure and intriguing horn variant out of the blue and mess up my plans for the weekend
We went thru (real) ZEN (a pr), our clone (as good) thru 6 more iterations ending up with a variation on RH84. You can do better than the ZEN, but do note tht you hace to work realy hard to make a bad EK84 amplifier. The best one we made was a PP Class A triode based on Eli Dutton’s El Cheapo.
dave
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Which variation was that, then? Figured there are so many variants of the RH84 with varying degrees of praise that it was easiest to go for a known "good" with the Zen. But I defer to the professionals!
The triode strapped El Cheapo sounds intriguing, maybe be a future build. Assuming it's the one you're talking about in this post.
We tired a few starting with as close as we could get to the RH84 original. We ended up with a monoblock design using parafeed and a triode EF86 up front. And no elco caps anywhere (that likely makes one of the biggest differences).
I have been thinking that this could go further. Simplier, it doesn’t need to be parafeed, 6N6P as the driver.
RH84 seems to provide the finesse of triode and the beef (a whiole 5w) of a pentode.
dave
I have been thinking that this could go further. Simplier, it doesn’t need to be parafeed, 6N6P as the driver.
RH84 seems to provide the finesse of triode and the beef (a whiole 5w) of a pentode.
dave