Anything from 15deg to about 45deg is ok with Tannoys as they have a 90deg conical horn although some are 60deg (some PA drivers and apparently Reds).
They work surprisingly well when you stand right between them too, very much like huge headphones.
That said I always preferred mine with their back to the wall and no toe-in, you can move my 12" up to 13ft apart before the dreaded stereo hole forms in the centre (I'm very much a near-field listener, I also like them somewhat above ear height).
The response is actually better off-axis than on, as previously mentioned.
I don't think there is an in series option with DMT215s or FSMs; it's either parallel or the secondary woofer does bass up to 250Hz or so and the DualConcentric takes over from there. Both woofer and DC are 8Ohm.
I do wonder how your friend influences the dispersion by changing the crossover.
I would have thought you'd have to change the horn to do so.
That said dispersion was never a problem for me, if I'd start from scratch 90deg is what I would choose anyway. Any wider and one starts to get nasty in-room reflections.
Friend of mine works in a studio were they use DynaudioAcoustics with a rather wider dispersion and you have to be really careful that EVERYTHING in the room is perfectly symmetrical otherwise judging left-right balance precisely becomes a gamble. A carelessly placed folder once ruined many mixes before they traced the problem.
I'd never use a dome tweeter without a waveguide to limit its dispersion to about 90deg.
From what I hear UREIs are rather like the poor cousins of Tannoys: similar but not the same. Tannoy even made the FSM-U which fits into soffits designed for UREIs. FSM-Us sold quite well in North America as many engineers preferred them but balked at the building work which would otherwise be required to fit Tannoys in existing studios.
They work surprisingly well when you stand right between them too, very much like huge headphones.
That said I always preferred mine with their back to the wall and no toe-in, you can move my 12" up to 13ft apart before the dreaded stereo hole forms in the centre (I'm very much a near-field listener, I also like them somewhat above ear height).
The response is actually better off-axis than on, as previously mentioned.
I don't think there is an in series option with DMT215s or FSMs; it's either parallel or the secondary woofer does bass up to 250Hz or so and the DualConcentric takes over from there. Both woofer and DC are 8Ohm.
I do wonder how your friend influences the dispersion by changing the crossover.
I would have thought you'd have to change the horn to do so.
That said dispersion was never a problem for me, if I'd start from scratch 90deg is what I would choose anyway. Any wider and one starts to get nasty in-room reflections.
Friend of mine works in a studio were they use DynaudioAcoustics with a rather wider dispersion and you have to be really careful that EVERYTHING in the room is perfectly symmetrical otherwise judging left-right balance precisely becomes a gamble. A carelessly placed folder once ruined many mixes before they traced the problem.
I'd never use a dome tweeter without a waveguide to limit its dispersion to about 90deg.
From what I hear UREIs are rather like the poor cousins of Tannoys: similar but not the same. Tannoy even made the FSM-U which fits into soffits designed for UREIs. FSM-Us sold quite well in North America as many engineers preferred them but balked at the building work which would otherwise be required to fit Tannoys in existing studios.
I was never a big fan of UREI but they did make an excellent variable active crossover many years ago. I had one and sold it to someone with a studio that paid me more than it cost new. I thought that you were intimating earlier that some of the Tannoy's were wired in series. People think that this is okay, but it not something to do.
On the use of a waveguide in front of a dome tweeter I understand what you are saying but this also comes with some real headaches unless you are using an active crossover. The waveguide will boost the apparent output at the cutoff frequency and start to roll off as the frequency increases. I am working on a desktop design, on the large size let's say and I have seriously considered with or without a waveguide. With an active crossover which I am going to use I can correct for this but otherwise it would be a detriment to the sound. I wouldn't do it with a passive network, by the time you add all the components to a high order crossover and include a slope in the network the power requirements go up quite a bit. One of the reasons I am here on this forum and another is to learn more about the correct implementation of active crossovers. Not just a straight from the book or data sheet implementation, but a matched design. Since I will be producing the drivers I can match exactly what I need. I have an easier time on the driver side but it was time to move over to the electronic side to go along with them.,
On the use of a waveguide in front of a dome tweeter I understand what you are saying but this also comes with some real headaches unless you are using an active crossover. The waveguide will boost the apparent output at the cutoff frequency and start to roll off as the frequency increases. I am working on a desktop design, on the large size let's say and I have seriously considered with or without a waveguide. With an active crossover which I am going to use I can correct for this but otherwise it would be a detriment to the sound. I wouldn't do it with a passive network, by the time you add all the components to a high order crossover and include a slope in the network the power requirements go up quite a bit. One of the reasons I am here on this forum and another is to learn more about the correct implementation of active crossovers. Not just a straight from the book or data sheet implementation, but a matched design. Since I will be producing the drivers I can match exactly what I need. I have an easier time on the driver side but it was time to move over to the electronic side to go along with them.,
I use modified BSS FDS360s since I'm not that good at all with electronics, they are cheap s/h these days and use plug in cards to change xover frequencies rather than those adjustable thingies. BSS has long stopped making them but they did publish tables to make your own cards. The advantage is that one can use 1% components while those variable ones are around 20%!
I don't think I'll ever build passive speakers unless forced at gun point! ;-)
Passives are just too fundamentally flawed in many respects IMO.
I had the chance to compare a few active v passives which were otherwise identical and it really is no competition at all.
Also an extra amp or two can work out cheaper than using boutiquey low resistance inductors and caps these days.
Another advantage of waveguides is that it brings the respective voice coils closer to each other in the vertical plane without resorting to electronic trickery like digital delays and I like to avoid unnecessary conversion steps. This might be a hang up of mine from the analogue era though as phono cartridges and the speakers which do the analogue conversions were always clearly the weak points.
To my ears having the tweeter coil in front of the woofer coil is more detrimental than vice versa.
Do you really make your own drivers?
There is one other guy here who does this but I forgot his name/moniker. I believe he is from India and his drivers looked very good indeed.
I don't think I'll ever build passive speakers unless forced at gun point! ;-)
Passives are just too fundamentally flawed in many respects IMO.
I had the chance to compare a few active v passives which were otherwise identical and it really is no competition at all.
Also an extra amp or two can work out cheaper than using boutiquey low resistance inductors and caps these days.
Another advantage of waveguides is that it brings the respective voice coils closer to each other in the vertical plane without resorting to electronic trickery like digital delays and I like to avoid unnecessary conversion steps. This might be a hang up of mine from the analogue era though as phono cartridges and the speakers which do the analogue conversions were always clearly the weak points.
To my ears having the tweeter coil in front of the woofer coil is more detrimental than vice versa.
Do you really make your own drivers?
There is one other guy here who does this but I forgot his name/moniker. I believe he is from India and his drivers looked very good indeed.
Charles Darwin,
To answer the last question, yes. I am producing the cone itself from a material that I developed as a challenge by someone else that was working with Dupont on a speaker development job. They couldn't create two that measured the same using their own process and I was asked if I could do something. One of my specialties is in product and material development and I took up the challenge. The company that wanted the technology went under before they really took off and I had a new material on my hands. I also developed my own magnetic circuit for a long throw motor with an umderhung voice-coil. I wasn't after max efficiency, I wanted lowest distortion numbers and have gotten there. I am in the midst of a beryllium dome tweeter development project to go with my cone loudspeakers. Put them together and you have a two way system. The cone driver goes 35hz to about 2.5khz but I prefer to cut at about 1.5khz. Right now it is a 6 1/2" but I also have done initial work on 3", 5 1/2". 8" and 10". Just a matter of optimizing each size.
I don't disagree with anything you said about passive crossovers. The cost of just large gauge copper magnet wire is out of site and the cost of multiple polypropylene caps isn't cheap either even if they are not so call boutique names. That I have seen with my own eyes is a fraud. I know someone, name to remain anonymous who makes caps and I watch them make those caps, they were made on the exact same lines with the same materials as there normal caps and just made to be pretty. They were in truth identical to production caps. One difference for one customer was that they used multistrand leads instead of standard leads and they looked nice but otherwise the same. I used to but these by the bag full with their names on them and I paid $1.00 for a cap. Sometimes he would just give me bags of them for nothing. I would mix and match caps and used 1% values as my final crossover in passive units. All were as good as you get in a passive network. The coils were the same way, precision wound. I even had made a winder to make them in-house when I needed a value we did not have pre-made.
On the waveguide on dome tweeter I do and don't always agree. Yes getting the voice-coils to vertically line up is nice this can also be done with a stepped baffle also. That has its own issues but everything is a tradeoff. If you use a waveguide on the dome and not on the cone driver then you have two devices with very different polar responses. If they are not close at the crossover point then that is a new issue. I can change the shape of the cone to modify the dispersion angle, but only to some extent before other issues crop up. Loudspeakers are a mixed bag of compromises, there is no ultimate answer there.
This is what brings me to this forum. I aim to use active electronics and create self powered systems that are created as a system and not as a conglomeration of parts. I can optimize the system by creating a synergistic electronic package and using my designs in loudspeakers do something that most do not do. If you close your eyes and listen to this 6 1/2" speaker you would swear that it is a large format speaker such as a 15" driver on the low end. It isn't like anything else I have heard, and I am being serious about that. Sometimes things just all balance out and work, this is one of those times.
To answer the last question, yes. I am producing the cone itself from a material that I developed as a challenge by someone else that was working with Dupont on a speaker development job. They couldn't create two that measured the same using their own process and I was asked if I could do something. One of my specialties is in product and material development and I took up the challenge. The company that wanted the technology went under before they really took off and I had a new material on my hands. I also developed my own magnetic circuit for a long throw motor with an umderhung voice-coil. I wasn't after max efficiency, I wanted lowest distortion numbers and have gotten there. I am in the midst of a beryllium dome tweeter development project to go with my cone loudspeakers. Put them together and you have a two way system. The cone driver goes 35hz to about 2.5khz but I prefer to cut at about 1.5khz. Right now it is a 6 1/2" but I also have done initial work on 3", 5 1/2". 8" and 10". Just a matter of optimizing each size.
I don't disagree with anything you said about passive crossovers. The cost of just large gauge copper magnet wire is out of site and the cost of multiple polypropylene caps isn't cheap either even if they are not so call boutique names. That I have seen with my own eyes is a fraud. I know someone, name to remain anonymous who makes caps and I watch them make those caps, they were made on the exact same lines with the same materials as there normal caps and just made to be pretty. They were in truth identical to production caps. One difference for one customer was that they used multistrand leads instead of standard leads and they looked nice but otherwise the same. I used to but these by the bag full with their names on them and I paid $1.00 for a cap. Sometimes he would just give me bags of them for nothing. I would mix and match caps and used 1% values as my final crossover in passive units. All were as good as you get in a passive network. The coils were the same way, precision wound. I even had made a winder to make them in-house when I needed a value we did not have pre-made.
On the waveguide on dome tweeter I do and don't always agree. Yes getting the voice-coils to vertically line up is nice this can also be done with a stepped baffle also. That has its own issues but everything is a tradeoff. If you use a waveguide on the dome and not on the cone driver then you have two devices with very different polar responses. If they are not close at the crossover point then that is a new issue. I can change the shape of the cone to modify the dispersion angle, but only to some extent before other issues crop up. Loudspeakers are a mixed bag of compromises, there is no ultimate answer there.
This is what brings me to this forum. I aim to use active electronics and create self powered systems that are created as a system and not as a conglomeration of parts. I can optimize the system by creating a synergistic electronic package and using my designs in loudspeakers do something that most do not do. If you close your eyes and listen to this 6 1/2" speaker you would swear that it is a large format speaker such as a 15" driver on the low end. It isn't like anything else I have heard, and I am being serious about that. Sometimes things just all balance out and work, this is one of those times.
Kind,
that is very impressive indeed!
I'd love to see some pictures of your driver and so would everyone else on here I'm sure.
That said I'd be **** scared working with beryllium considering how poisonous it is supposed to be but I'm sure you know what you are doing provided you are not posting from an intensive care unit! ;-)
Personally when it comes to conventional cones and domes I'm an old-fashioned guy and generally prefer paper cones and silk domes but that's just me.
Do you plan on selling drivers commercially (or otherwise) at some point?
When it comes to cones and dispersion I like to pick ones that allow use up to where they start beaming at 90deg so no real problems there.
I like your thinking regarding motor design. Originally I was after some ATC woofers because of the underhung coil but eventually cheapened out and went for Volt radials instead. I was helped along by a subwoofer test I found online in which the PMCs using radial Volts were the only ones together with some huge Genelecs which never exceeded 10% THD at any SPL level.
that is very impressive indeed!
I'd love to see some pictures of your driver and so would everyone else on here I'm sure.
That said I'd be **** scared working with beryllium considering how poisonous it is supposed to be but I'm sure you know what you are doing provided you are not posting from an intensive care unit! ;-)
Personally when it comes to conventional cones and domes I'm an old-fashioned guy and generally prefer paper cones and silk domes but that's just me.
Do you plan on selling drivers commercially (or otherwise) at some point?
When it comes to cones and dispersion I like to pick ones that allow use up to where they start beaming at 90deg so no real problems there.
I like your thinking regarding motor design. Originally I was after some ATC woofers because of the underhung coil but eventually cheapened out and went for Volt radials instead. I was helped along by a subwoofer test I found online in which the PMCs using radial Volts were the only ones together with some huge Genelecs which never exceeded 10% THD at any SPL level.
Charles,
I just got home and my main desktop computer decided that it doesn't want to start. I hope it isn't one of the hard drives but probably will turn out that is the issue. It is dual boot with both Windows 7 and linux so which drive will it be.... I will post a picture of the speaker when I get a chance, I don't really feel like messing with the computer right now.
On the beryllium you are right and wrong at the same time. Beryllium is very toxic when it is powdered form or broken into small pieces that can get in your lungs. The way that Brush Wellman supplies it, it is a finished dome shape cut to the final outside dimensions that you specify so you really aren't working the material. My cousin is a PHD in metallurgy and used to work for the Air Force as a crash investigator. He works on Star Wars applications now but is a ready source of information. You are only doing s sub-assembly of the voice-coil former joint and the surround you are using. I am going to probably create my own surround and not use a standard surround unless I can find one with the material properties that I desire. The surround that I will use on the 6 1/2" speaker I know I have to redesign as I can not purchase one that allows me to reach maximum excursion before running out of physical distance. That is the current limitation of the device. I have designed a new surround and it is not a standard 1/2 round or M-roll design. I just can't get where I am going with either design. My design will be highly unusual.
I just got home and my main desktop computer decided that it doesn't want to start. I hope it isn't one of the hard drives but probably will turn out that is the issue. It is dual boot with both Windows 7 and linux so which drive will it be.... I will post a picture of the speaker when I get a chance, I don't really feel like messing with the computer right now.
On the beryllium you are right and wrong at the same time. Beryllium is very toxic when it is powdered form or broken into small pieces that can get in your lungs. The way that Brush Wellman supplies it, it is a finished dome shape cut to the final outside dimensions that you specify so you really aren't working the material. My cousin is a PHD in metallurgy and used to work for the Air Force as a crash investigator. He works on Star Wars applications now but is a ready source of information. You are only doing s sub-assembly of the voice-coil former joint and the surround you are using. I am going to probably create my own surround and not use a standard surround unless I can find one with the material properties that I desire. The surround that I will use on the 6 1/2" speaker I know I have to redesign as I can not purchase one that allows me to reach maximum excursion before running out of physical distance. That is the current limitation of the device. I have designed a new surround and it is not a standard 1/2 round or M-roll design. I just can't get where I am going with either design. My design will be highly unusual.
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