-speaking of drivers for this design, here is the Test Bench of the Radian 745PB:
Test Bench: Radian Audio Engineering 745PB 1.4” Compression Driver | audioXpress
Other than the typical "hash" at the top of the pass-band, pretty good on a sub-par horn.
Still, I'd recommend the 18 Sound ND 1460 A or ND 1480 A .. and a good efficient ribbon around 6 kHz.
For the midbass section I'd pick the Faital Pro 12PR300 16 ohm x2 wired in parallel with a large volume bass-reflex and a much lower tuning freq. than typical.. (..sort of "sealed +") and a good filter for integration + baffle-step compensation.
Test Bench: Radian Audio Engineering 745PB 1.4” Compression Driver | audioXpress
Other than the typical "hash" at the top of the pass-band, pretty good on a sub-par horn.
Still, I'd recommend the 18 Sound ND 1460 A or ND 1480 A .. and a good efficient ribbon around 6 kHz.
For the midbass section I'd pick the Faital Pro 12PR300 16 ohm x2 wired in parallel with a large volume bass-reflex and a much lower tuning freq. than typical.. (..sort of "sealed +") and a good filter for integration + baffle-step compensation.
If I’m reading you correctly you already have a pair of Ariels. Is it too complex a matter to just measure the DCR of the inductor currently in place?
Lynn talks about the Ariel here: Nutshell Hifi
He recommends using 10 or 12AWG air core inductors from North Creek. North Creek is no longer in business and their inductor data sheet/price list is gone as well. From my own experience, North Creek’s listed DCR was lower than the actual DCR of the product I received. For that reason I started buying the slightly less expensive 10AWG air core inductors from Solen. Parts Express & Madisound also carry 12AWG air core inductors.
Lynn talks about the Ariel here: Nutshell Hifi
He recommends using 10 or 12AWG air core inductors from North Creek. North Creek is no longer in business and their inductor data sheet/price list is gone as well. From my own experience, North Creek’s listed DCR was lower than the actual DCR of the product I received. For that reason I started buying the slightly less expensive 10AWG air core inductors from Solen. Parts Express & Madisound also carry 12AWG air core inductors.
Yes, I bought Ariels second hand, but crossover is mess with budget components and i need to rebuilt it. I cant afford 10 or 12 AWG coils with low DCR at the moment cause budget is tight, shipping to my country is really expensive and we dont have anyone making something like that here. Thx for answer, Brinkman
The DCR of the Ariel inductors are fairly non-critical. Anything less than 0.7 ohm is fine. My first choice would be the Solen Litz inductors, but can be expensive in the larger values. A good alternative are iron-core inductors with transformer-style laminations; I would avoid ferrite-cores because they are prone to sharp-onset saturation problems. Why not keep the inductors you already have? The worst that can happen if the DCR is too high is the bass will get kind of boomy. I do recommend good-quality caps, though, at least for the tweeter circuit.
As for the Beyond the Ariel project (the genesis of this thread), I regard Gary Dahl's build as the definitive version. ScottG's variant, described above, is an excellent alternative. I've heard nothing but good things about the 18Sound ND1480A (aluminum) compression driver, and if ScottG endorses the Faital Pro 12PR300 16 ohm x2 wired in parallel, that sounds promising. The basic concept is a 2-way system with quick decay characteristics (like the Ariel), smooth response in the HF section, high efficiency, and a fundamentally simple design.
If controlled directivity is more important to you, then other horn profiles are a (much) better choice. The HF crossover then gets more complex (in-band EQ is necessary, and possibly a notch filter), and some care has to be exercised to make sure that the time-decay characteristics remain favorable.
As for the Beyond the Ariel project (the genesis of this thread), I regard Gary Dahl's build as the definitive version. ScottG's variant, described above, is an excellent alternative. I've heard nothing but good things about the 18Sound ND1480A (aluminum) compression driver, and if ScottG endorses the Faital Pro 12PR300 16 ohm x2 wired in parallel, that sounds promising. The basic concept is a 2-way system with quick decay characteristics (like the Ariel), smooth response in the HF section, high efficiency, and a fundamentally simple design.
If controlled directivity is more important to you, then other horn profiles are a (much) better choice. The HF crossover then gets more complex (in-band EQ is necessary, and possibly a notch filter), and some care has to be exercised to make sure that the time-decay characteristics remain favorable.
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If cost is really a driver of the project, you can do a lot worse than track down a pair of Klipsch Cornwalls (cabinet in good condition, with all drivers good and a working crossover) and hang out on the Klipsch forums for info on upgraded crossovers and modernized drivers. My take is: this model was Paul W. Klipsch's flattest-response speaker (much more so than Heresies), and not only that, is very responsive to tweaks and modernizing.
The Heresy has a nasty response step ... the MF and HF drivers are nearly 5 dB hotter than the bass driver, while the Cornwall is close to flat (the 15" bass driver is a little bit more efficient, while the MF and HF drivers use a lower tap on the autoformers in the crossover). Upgrading the LaScala, Belle Klipsch, or a full-scale Klipschorn is a bigger job, since the folded bass horn has wacko response at the top of its range, and the MF horn is pushed to its limits to meet the upper part of the bass horn.
Taking on anything Altec is much more ambitious, involving serious crossover work and tracking down better horns than the usual 511 and 811's. The Altec 604 Duplex, although beautiful and a remarkable history in the US recording studios, is really really hard to equalize ... DSP is about the only method I can think of. By contrast, the phenolic-diaphragm Klipsch drivers are more tolerant of simple crossovers and out-of-band energy, and, by lucky coincidence, the MF horn and direct-radiator bass driver of the Cornwall are nearly perfectly time-aligned.
P.S. This mostly applies to enthusiasts in the USA; Klipsch isn't as common outside this country, and they've been made in Hope, Arkansas since the late Forties, so there are lots and lots of them around.
The Heresy has a nasty response step ... the MF and HF drivers are nearly 5 dB hotter than the bass driver, while the Cornwall is close to flat (the 15" bass driver is a little bit more efficient, while the MF and HF drivers use a lower tap on the autoformers in the crossover). Upgrading the LaScala, Belle Klipsch, or a full-scale Klipschorn is a bigger job, since the folded bass horn has wacko response at the top of its range, and the MF horn is pushed to its limits to meet the upper part of the bass horn.
Taking on anything Altec is much more ambitious, involving serious crossover work and tracking down better horns than the usual 511 and 811's. The Altec 604 Duplex, although beautiful and a remarkable history in the US recording studios, is really really hard to equalize ... DSP is about the only method I can think of. By contrast, the phenolic-diaphragm Klipsch drivers are more tolerant of simple crossovers and out-of-band energy, and, by lucky coincidence, the MF horn and direct-radiator bass driver of the Cornwall are nearly perfectly time-aligned.
P.S. This mostly applies to enthusiasts in the USA; Klipsch isn't as common outside this country, and they've been made in Hope, Arkansas since the late Forties, so there are lots and lots of them around.
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Apologies for resurrecting an old thread. I don't know if anyone else ever actually built the Symmetric Reichert circuit? However, I have just completed the build on one of a pair of monoblocks based on it. I made some minor changes - the driver valves are triode connected 6V6's rather than half 6SN7's, both power supplies use 5AR4 rectifiers, and I upped the values of the coupling caps to 0.33uF and 0.47uF for the input -> driver and driver -> output interfaces, and also tweaked the grid to ground resistor values based on the results from a Spice model. CCS's on the 6V6's were from K&K.
The results, even based on listening to just one channel, are pretty sublime so I can definitely recommend trying it out. The clarity and transparency are extraordinary, seemingly even better than the OTL design I was using before.
Anyway, just putting this here in case anyone is interested.
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zigzagflux built something similar:
Testing on latest PP 300B build
NO input transformer (balanced differential preamp required) - 12SN7 differential cap coupled to 46 triode strapped differential - bifilar PP IT - 300PP
Testing on latest PP 300B build
NO input transformer (balanced differential preamp required) - 12SN7 differential cap coupled to 46 triode strapped differential - bifilar PP IT - 300PP
I ended up with no input transformer, 6SN7 differential input LL1692A step down + another 6sn7 LL1692A step down. Both 6sn7 stages shunt VR on the centre tap of the IT. Tried direct coupled 6sn7 first stage and exotic Teflon capacitors but the IT step down sounded better (IMO). If using power tubes as drivers I found triode connected 6550 (Electro Harmonix) sounds better than the 6V6 triode connection.
Frank
Frank
Sure thing, here's the original schematic that Lynn shared in 2015:
This is a link to a PDF of the circuit as I built it: https://user.fm/files/v2-60b696c64599859245915e462f3f844c/Newton_300B.pdf
Hey Lynn, thanks a lot for your suggestion. At time of writing I didn't knew that the Vifa's went out of production, so I was thinking I can easily get some and build enclosures around them. Unfortunately I couldn't get any, was even looking for used ones, but no luck at all.
Hello everybody.
I would like to thank Mr. Lynn for creating and generously sharing the Ariel project. I bought the components in 2005 and they were forgotten for many years. During 2020 I had time to build a pair of ARIEL ME2 and the result was spectacular. In the future I will build a suitable subwoofer. Here's a video of when I made the coating.
I would like to thank Mr. Lynn for creating and generously sharing the Ariel project. I bought the components in 2005 and they were forgotten for many years. During 2020 I had time to build a pair of ARIEL ME2 and the result was spectacular. In the future I will build a suitable subwoofer. Here's a video of when I made the coating.
I'm not sure if these folks are reputable, but perhaps work an inquiry... They show as being stocked. https://www.artsound.gr/product/vifa-p13wh00-08-5½-midwoofer/
Regarding the Beyond the Arial MF/HF horn section. I took a look at some vintage or readily available bi-radial horns, mostly PA inspired available on E-bay to see what might be had inexpensively, or as templates for re-casting a horn with Hi Fi refinements. Only as an approach for learning of basic principles, history and a proclivity for dumpster diving since I am convinced by Jean Michel Le Cleach and others about optimal diffraction free flares.
I found some horns with nice flair shapes in fiberglass, metal and plastic with really nice curves and construction in the body, but all of these types of horns appear to include a 2nd compression section before the first stage of exponential flare occurs. And, often it appears there is section with 4 flat walls until curved walls at the top and bottom begin.
For example, see these images of a Peavy horn for the C22A. This plastic horn is really well manufactured. The horn is made in two pieces of injection molded plastic that are screwed together. The two halves are identical since they designed the top and bottom to be exact mirrors of each other. But, this horn also includes the 2nd compression area, flat wall section then curved section construction. This horn would be problematic for me to copy since it has a .875" throat with screw on mounting, but more fundamental to this horn and the others is that I could not use these horns and follow the strategies for avoiding reflections in the throat as I understand the principles from Le Cleach and Geddes. And, just smoothing the throat would change the expansion rate. There's just too much going on there.
I'm curious about the purpose of these features and what other might think about their contribution to a good sounding horn. Or, maybe more useful are thoughts about the current crop of PA horns. I notice some of the easy to procure PA horns, in particular the HF horns, have nice smooth throats and a construction I think would be characterized as a wave guide or maybe OSWG horn? Also, I've notice that some very experienced horn aficionados like @POOH have recommended some mass produced horns as good options. What's the state of offerings available to the enthusiast for cheap horns that approach the Azurahorn performance?
I found some horns with nice flair shapes in fiberglass, metal and plastic with really nice curves and construction in the body, but all of these types of horns appear to include a 2nd compression section before the first stage of exponential flare occurs. And, often it appears there is section with 4 flat walls until curved walls at the top and bottom begin.
For example, see these images of a Peavy horn for the C22A. This plastic horn is really well manufactured. The horn is made in two pieces of injection molded plastic that are screwed together. The two halves are identical since they designed the top and bottom to be exact mirrors of each other. But, this horn also includes the 2nd compression area, flat wall section then curved section construction. This horn would be problematic for me to copy since it has a .875" throat with screw on mounting, but more fundamental to this horn and the others is that I could not use these horns and follow the strategies for avoiding reflections in the throat as I understand the principles from Le Cleach and Geddes. And, just smoothing the throat would change the expansion rate. There's just too much going on there.
I'm curious about the purpose of these features and what other might think about their contribution to a good sounding horn. Or, maybe more useful are thoughts about the current crop of PA horns. I notice some of the easy to procure PA horns, in particular the HF horns, have nice smooth throats and a construction I think would be characterized as a wave guide or maybe OSWG horn? Also, I've notice that some very experienced horn aficionados like @POOH have recommended some mass produced horns as good options. What's the state of offerings available to the enthusiast for cheap horns that approach the Azurahorn performance?
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Logically speaking, you are asking about reverse engineering to discover the purposes of features of horns, a worthy enterprise but not the same as designing to solve a requirement.
Horns seem to me to be a solution in search of a problem. And for home audio, maybe all the "problems" can be solved better in other ways. Two exceptions are: (1) a bass horn which seems to me a natural home for horns (did I say it had to be feasible?) and (2) control of directionality (but these days, directional control is taking second place to robust ambience) .
Ben
Horns seem to me to be a solution in search of a problem. And for home audio, maybe all the "problems" can be solved better in other ways. Two exceptions are: (1) a bass horn which seems to me a natural home for horns (did I say it had to be feasible?) and (2) control of directionality (but these days, directional control is taking second place to robust ambience) .
Ben
The abrupt change in profile creates diffraction. The purpose of this is to get a wide coverage angle at high frequencies. A constant coverage angle is a requirement in sound reinforcement applications.
For home or studio applications this is not the case. The direct response of the speaker should be flat on the listening axis (with a 15° toe-in, thus at 15°), but the total response (including all reverberations) should be flat from 160 Hz to 1 kHz and then drop above 2.5 kHz at a rate of -1 to -2.5 dB/octave. The corner frequency can be anywhere between 1 and 2.5 kHz and a linear fit of the drop-off of the total response should result in a -6 to -10 dB crossing at 20 kHz. The majority of loudspeakers that sound neutral fulfill this requirement (LS3/5, LS50, Revel ...).
This is achieved in a standard sized living room when a horn is used with a hypex expansion rate (T: 0.5 - 1, includes elliptic expansion rate) and an expansion rate cut-off of 350 - 450 Hz. The AH-425 fulfills these requirements. I would not consider the Azurahorn expensive (without shipping costs), but in Europe alternatives such as the JMLC-400 or a Jabo KH-53 A can be bought at a lower cost.
For a non-axisymmetric horn that has a larger width than height, a lower expansion rate cut-off should be chosen: e.g. 300 Hz for the Iwata type.
Most sound reinforcements horns will sound colored when used in a normal room (vs. in a large venue). But the Faital Pro LTH-142 might be worth a try.
For home or studio applications this is not the case. The direct response of the speaker should be flat on the listening axis (with a 15° toe-in, thus at 15°), but the total response (including all reverberations) should be flat from 160 Hz to 1 kHz and then drop above 2.5 kHz at a rate of -1 to -2.5 dB/octave. The corner frequency can be anywhere between 1 and 2.5 kHz and a linear fit of the drop-off of the total response should result in a -6 to -10 dB crossing at 20 kHz. The majority of loudspeakers that sound neutral fulfill this requirement (LS3/5, LS50, Revel ...).
This is achieved in a standard sized living room when a horn is used with a hypex expansion rate (T: 0.5 - 1, includes elliptic expansion rate) and an expansion rate cut-off of 350 - 450 Hz. The AH-425 fulfills these requirements. I would not consider the Azurahorn expensive (without shipping costs), but in Europe alternatives such as the JMLC-400 or a Jabo KH-53 A can be bought at a lower cost.
For a non-axisymmetric horn that has a larger width than height, a lower expansion rate cut-off should be chosen: e.g. 300 Hz for the Iwata type.
Most sound reinforcements horns will sound colored when used in a normal room (vs. in a large venue). But the Faital Pro LTH-142 might be worth a try.