You're welcome! Yeah, higher math is literally Greek to me, so use well proven rules-of-thumb based on basic math.
Forgot to post my fave website for the basics and maybe a primer for you before delving into MJK's docs: Resonances of open air columns
GM
Forgot to post my fave website for the basics and maybe a primer for you before delving into MJK's docs: Resonances of open air columns
GM
I've skimmed through this entire thread now. This design seems well made and produced in a number of different versions. There's even an aluminum version!
I've been looking for a new project for a while.
My current setup
Nad356BEE
Frugel-Horn Mk3 (18mm MDF, fostex fe126en) they cannot fully drive the room they are in since the room is quite large. I also think they match the amp poorly.
Room size is about 4,7m* ~6m
So I was hoping to get some tips on what would match the amp and better be able to drive the larger room.
I was thinking of buying a volt+ D with DAC and hooking it into my raspberry pi (which has all of my Flacs mounted) as an alternative amp if that changes things.
What I am hoping for here is a suggested design out of the many metronomes. I was also hoping I could bribe someone to produce a cutout plan so I can have the speaker cut out at a woodshop. I think 19mm is readily available here. Whether I go for MDF or plywood depends on if I can actually find high quality plywood. Not sure about that .
I've been looking for a new project for a while.
My current setup
Nad356BEE
Frugel-Horn Mk3 (18mm MDF, fostex fe126en) they cannot fully drive the room they are in since the room is quite large. I also think they match the amp poorly.
Room size is about 4,7m* ~6m
So I was hoping to get some tips on what would match the amp and better be able to drive the larger room.
I was thinking of buying a volt+ D with DAC and hooking it into my raspberry pi (which has all of my Flacs mounted) as an alternative amp if that changes things.
What I am hoping for here is a suggested design out of the many metronomes. I was also hoping I could bribe someone to produce a cutout plan so I can have the speaker cut out at a woodshop. I think 19mm is readily available here. Whether I go for MDF or plywood depends on if I can actually find high quality plywood. Not sure about that .
I try to avoid suggesting one design (since even within the metronome sub-type, all the different versions are different designs) over another as I'm not keen on taking on that kind of responsibility. However, as an observation, your amplifier certainly isn't optimal for the FE126En, or to put it another way, the 126 was designed with a view toward a different type of amplifier. I don't know what your current speaker wire is, but as a temporary measure while you decide on a new loudspeaker, try replacing with a single strand of 24ga for each leg. Over, for example, a typical 3m run (6m loop length) it will add about 1ohm of series resistance, artifically raising driver Q and some LF output from the speaker which at present is probably over-damped electrically speaking. There's a limit to how far this can go of course before the wire simply can't handle the current demands on LF dynamic peaks and 'clips' them (for want of a better word). However, it's very inexpensive to try as a temporary measure and can help a little in such cases.
Another alternative is to replace the 126 with, say, an Alpair 7 variation. The 4in MA units were the baseline for FH3, the 126 an option, and while they have less sensitivity, they have superior LF potential in that encosure. In a room that size a 4in - 4.5in driver even in a horn is not likely to drive it to particularly high levels, but they should do a bit better than what you're currently using, until you get something a bit larger / more to your requirements.
Another alternative is to replace the 126 with, say, an Alpair 7 variation. The 4in MA units were the baseline for FH3, the 126 an option, and while they have less sensitivity, they have superior LF potential in that encosure. In a room that size a 4in - 4.5in driver even in a horn is not likely to drive it to particularly high levels, but they should do a bit better than what you're currently using, until you get something a bit larger / more to your requirements.
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Right. The thing is I do not know how to figure out what would be good enough for the room, matches the amp. (I can just buy a class D amp if the one I have is difficult to suggest something for) I want to build the metronomes because of simplicity of the design and how they can scale easily to different configurations and speaker sizes. The reason I built the FH3 is because of the number of builds and the seriousness of the calculations and evalutions behind them. Some people give audiophiles a bad name by buying too much moonrock or trinkets. I found none of that around the FH3. I see a similar trend all over this forum and the metronome in particular.
Dave said the same thing but I haven't had time to do anything about it. I am thinking about ordering a Volt+ D with DAC.
Will,. that be better for my fostex?
My current speaker wire is a thick braided copper wire. Dave suggested the same thing here. Still haven't gotten around to fixing this.
I uuuh. "slipped" and order a pair of alpair 7.3
I won't be baited here...
However, one using a larger driver with a middling[ish] Q will likely suit. Possibly. That's a relief, because FH3 was designed by little old me, Dave & Chris, and we're not into moonrocks. Not for audio anyway, although I'd love to have one 'just because'. We also did some of the early metronomes too, which lurk on the FH site. The metronome is basically a mass-loaded Voigt horn; it happens to expand in two dimensions rather than one, although functionally it makes little difference; the aesthetics however offer something a bit different. As an alternative, FHXL might suit. Like FH3 but bigger and with more LF & general output capacity.
Unlikely. The 126 likes & was largely intended for use with an amplifier with a higher output impedance e.g. a SET valve design, so I doubt most class D amps would qualify in that sense, whatever their other merits (not knocking them -I have a pair myself that get daily use).
It's not a 'fix' as such, just something to try out; the electrical engineering aspect in terms of resistivity and driver behaviour are solid, so for the minimal time involved you may find it worth a shot. Either extract a twisted pair from a piece of CAT5 network cable, or two-core copper bell wire is also often 24ga or thereabouts, so should do the same job. Terrible for most loudspeakers but in this particular case with your amplifier and the 126 possibly worth trying for the reasons mentioned. If it helps, great. If not, it probably only cost about £5 to try.
I uuuh. "slipped" and order a pair of alpair 7.3
I suspect you'll prefer them to the 126 given your current setup.
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Some instructions on what to read up on would appreciated. I am an engineer, I've got a master of science in biotechnology and I am a self learned systems architech within software (this is actually the area where I excel), but this area here is new to me so some help is appreciated.I won't be baited here...
Some moonrock would be so nice to have on a shelf somewhere.
What is it really made for then? Remember, I am a novice when it comes to audio.
I do like the idea of it. I probably have some cat5 somewhere.
It is worth mentioning that I really love my FH3. Since I moved in september I haven't been able to listen to them as much as before. Before I got my NAD I had a Rank Arena 1020R. early 1970ies but it works ok.
See here:
YouTube
So what do I do with my fe126en then? How about a kongo spawn? And what do I drive them with
When I built my FH3 they really taught me the nuances of music. I listened to a lot of "2 cellos" and some "vitamin string quartet" for the purity of sound.
I also re-listened to some of the stuff I usually listened to and started hearing how bad the recordings were.
Addendum: my pc has a Music streamer II 2 DAC with a pair of Sennheiser HD 570 headphones. I changed the drivers a few years back. They have served me well.
The amp may be better (the NADs tend to be good), but it will not likely be a good match. Most (but not all, i have seen 1 Japanese hi-Z amp — big bucks thou) Class D amps pride themselves on low output impedance output stages (as if it is considered an advantage) so not what you are looking for. Good for bass thou.
The kind of amp the Fostex FExx6 tend to like are single ended tube amps — DHT triodes being the leading candidtaes, but SE pentodes with no feedback (they usually have some) are almost pure current amps (HiZ). There are a few SS current amps, the Firstwatt F1 & F2 for example. The ACA used as mono-bloks with thin wire tends towards hiZ and is a cheap entry.
Notes on the Volt amp: The 60w rated power is not FTC and is very dependent on the power supply voltage. !0w / channel is probably more realistic. Why an acrylic case. Class D amps, by their very nature, have a lot of RF emission, a class D should to be in a metal case to block the RF.
dave
I have a pair of TB W4-1320SJs and 1320SIFs (SJ is 89db, SIF is 88db, QMS and Vas are a little different between the two) and am wondering if I can make a bipolar metronome with them. Maybe even bipolar tweeters too, using maybe the tiny 3/4" Daytons, just for experimentation. I read where the design for the FE108 is similar enough for one 1320, but I do not know how to make them into bipolar or whether even the slightly different models will work in bipolar setup.
Thoughts? Suggestions?
Thoughts? Suggestions?
An interesting dilemma. Usually you want the same drivers, but if the bass loading is similar it may well work. You would need to sim them and see what an appropriate Met would be. If it ends up that the lines are similar then it may well work. On 1st blush i would point the less sensitive one towards the back, but you would have to listen both ways.
If you have 2 of the same driver, the formula is easy, double the cross-section, and use 2 vents (or one that is equivalent),
dave
If you have 2 of the same driver, the formula is easy, double the cross-section, and use 2 vents (or one that is equivalent),
dave
An off topic question. The use of the apostrophe here is wrong. It implies ownershup not more than one. Is this an auto correct thing or is it a deliberat thing. This is not the only instance, it seems to happen more often than not, or is it just that the anal side of me wanting to keep the forum tidy means these errors stand out more?
Also, a lot of extra carriage returns and excess use of quotes.
It makes for a lot of janitor work.
dave
diyAudio moderation team.
BTW i fixed the original post removing the superfluous punctuation.
PS: my personal errors are usually bad typing or spelling, but i do try to fix them (ie i am not without my shortcoming either)
W4-1320SJ - 4" Paper Full Range - TB SPEAKER CO., LTD.
W4-1320SIF - 4" Paper Full Range - TB SPEAKER CO., LTD.
I went and actual look at these driver’s data.
TB has the bad habit of mix & natch to create a huge range of simialr drivers as they burn thry parts (what we see in diy is just a small fraction of whatthey make, and are often runs based on left over parts). Looks like the same maoving parts in a different basket and different kinds of magnets.
The only spec that might have significant impact is a small difference in Vas (18% or so). Given the variance i have seen in TB QC and the variance in T/S depending on the weather (mostly temp & air pressure) this number is within the error bars of the data.
So i suspect that it could well work out when you ad din that Mass Loaded lines tend to have a good tolerance for differences in drivers (ie box tends to swamp driver, unlike a typical BR). Average the Vas (ie just add them together) and do a sim. Qt, Fs remain the same, MJK uses BL (so average that too).
Scott?
dave
You are indeed correct, it wasn't exactly deliberate, just me in a rush typing at work.
Thank you for the fix
I do not know how to sim them - is there a recommended tutorial to learn from or does whatever sim used have a starting guide? I started looking into this but as I am at work, it's only here and there. On the FH site the link to Steve's Metronome page doesn't work.
Thank you for the fix
I do not know how to sim them - is there a recommended tutorial to learn from or does whatever sim used have a starting guide? I started looking into this but as I am at work, it's only here and there. On the FH site the link to Steve's Metronome page doesn't work.
Why i pinged Scott. He can do a sim in his sleep (almost). He will also have a better take on whether my guess that it could work is correct.
There are simulators, bu tthe best one is NLA, the next is no longer supported (stil usable but seems hardish to install, but only on those damn Windoz boxes) and the supported one, no-one but the authour seems to know how yo use damping and the sims you see are hard to interpret. All are also only windoz which i avois as much as possible.
dave
There are simulators, bu tthe best one is NLA, the next is no longer supported (stil usable but seems hardish to install, but only on those damn Windoz boxes) and the supported one, no-one but the authour seems to know how yo use damping and the sims you see are hard to interpret. All are also only windoz which i avois as much as possible.
dave
Just average the specs to design with; this can even be done with somewhat different sets of specs, i.e. the "Compound Driver" approach: https://web.archive.org/web/2012031...ndell/xentar/1179/theory/dddllqd/dddllqd.html
GM
I kinda figured it would be something like that - the specs on the TB drivers are close enough and the unit variations are wide enough that they would be averaged together. I have not found a speaker/metronome simulator called NLA using google. I found a graphics design package called NLA. I have seen XRK on here do some simulator work for the metronome.
He is referring to No Longer Available MJK's Quarter WL MathCad worksheets and Leonard Audio's frustrating to install LA_TL program: Transmission Line Modelling Software
Original Installation Guide: Installation Guide | Leonard Audio
New Installer: https://www.diyaudio.com/forums/sof...n-line-modelling-software-17.html#post5160274
HELP File: Help File | Leonard Audio
GM
Original Installation Guide: Installation Guide | Leonard Audio
New Installer: https://www.diyaudio.com/forums/sof...n-line-modelling-software-17.html#post5160274
HELP File: Help File | Leonard Audio
GM
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FWIW, I've had a quick gander. Using the compound driver approach to derive a spec., & assuming 1/2ohm series R for wire, connection resistance, then this should work acceptably:
L = 52in
St = 4in x 4in
Sl = 10in x 10
Zd = 21 3/8in
Dv = 4in
Lv = 2in
All internal walls lagged 1/2in - 3/4in acoustic fibreglass board, SAE-F13 felt, jute, Ultratouch or similar (avoid acoustic foam). Duct fires out the base in usual Metronome fashion. This is more or less a flat anechoic alignment; the down-firing duct may provide some damping, but adjust as desired.
Fb = 51Hz
F3 = 46Hz [nominal anechoic]
F6 = 42Hz [nominal anechoic]
L = 52in
St = 4in x 4in
Sl = 10in x 10
Zd = 21 3/8in
Dv = 4in
Lv = 2in
All internal walls lagged 1/2in - 3/4in acoustic fibreglass board, SAE-F13 felt, jute, Ultratouch or similar (avoid acoustic foam). Duct fires out the base in usual Metronome fashion. This is more or less a flat anechoic alignment; the down-firing duct may provide some damping, but adjust as desired.
Fb = 51Hz
F3 = 46Hz [nominal anechoic]
F6 = 42Hz [nominal anechoic]
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From looking at the other plans detailed on the FH Metronome page, most designs include only lining on panels behind driver. In the bipolar design, is that the back panel only or the front and back? Something about these drivers make it suggested to have full lining on all walls?
Can the aspect ratio still be adjusted in this design?
Does it have an internal brace like other bipolar designs? Full length or partial?
Thanks for the replies and the quick sim Scott! I am excited to begin!
Can the aspect ratio still be adjusted in this design?
Does it have an internal brace like other bipolar designs? Full length or partial?
Thanks for the replies and the quick sim Scott! I am excited to begin!