Diy Question thread

[3DSonics]

Hi,

Firstly, I wouldn't use a first order. So your assumption that I would is incorrect.

Again, you are mistaken. I do not Ass U Me (assume). I work strictly with the statements you place in the public domain, such as:

"Why would you buy a crossover when you can build a 1st order crossover using a couple parts ?"

Secondly, why would you use a second or third order when you can just use a single cap in series with the tweeter, if you chose the drive units and construction very carefully, and even avoid the phase issues associated with higher order designs ?

Funnily enough, my current speaker (the breadboxes you took so extreme exception to earlier) works exactly like that, however I am a pragmatist, I use what works. I have no religeous attachment to "no crossover", "high order crossover", "low order crossover" or any such stuff. I tend to use what actually suits the job at hand and results bin audibly superior results.

And as it so happens, my fellow countryman Siegfried Linkwitz illustrated that a certain ACOUSTICAL slope, given time alignment MUST result in perfect integration of two spatially seperate sound sources. Which means that an actual "4th order LR crossover" in electrical terms does not work, mainly because the proponents are clearly analphabeths....

In fact, some hi end speakers do.

I am quite familiar with them. However in the vast majority of cases (in fact I am hard pressed for a counter example, something which you no doubt can provide) the actual ACOUSTIC function is anything but first order.

For illumination, my current (potentially commercial) speaker project uses a first order lowpass on the woofer and a 2nd order highpass on the tweeter. Yet the resultant acoustical slopes (and phase et al) makes for a near perfect 4th order LR crossover at 2KHz.

And unsurpringly, the result, even with strictly simulation derived crossover values (we all have to start somewhere) is not at all bad for a true 2-way.

L8er T

PS, our "development" speakers include both ATC conventional small 2-way monitors and Epos "1st order highpass only" speakers, together with the usual selection of really freaky stuff, including Horns, dipoles and fullrangers (including the "breadboxes")....

 

[3DSonics]

Hi,

Could you explain why the MEG RL901K have that particular radiation pattern in the bass frequencies ?

Yes, I could.

Ciao T

PS, anyone reasonably versed in the arts (as they often say in patent applications) can.

 

[3DSonics]

Hi,

Johnny, you deliberatly altered your quote of my writings.

I suggest you take remidial action immediatly, as your actions consist legally speaking of libel. In the UK this is a prosecutable offense.

I suggest you consider remidial action.

Kind regards Thorsten

 

[dean.l]

johnny can I just establish something?

you are kindly offering your help but know hardly anything about digital circuits,

you don't see the point in valves because they use too much voltage? *ask tim aparantly* (deleted post in cd thread)

speakers you are a bit iffy with.

so that leaves anologue ss as your expertise?

in a power amplifier what type of output transistor do you prefer?
mosfet/fet etc

do you think hardwiring is better or pcb? do you make your own boards? what board material do you prefer ?

what components do you favour in any one area, psu etc?

 

[3DSonics]

Hi,

I'm not the J'ster....

in a power amplifier what type of output transistor do you prefer?
mosfet/fet etc

N-Channel IGBT in a circlotron arrangement.

do you think hardwiring is better or pcb? do you make your own boards? what board material do you prefer ?

From experience, hardwiring really is best (though as circuit impedance goes down the distance reduces), Aralon and/or Teflon/Fibre boards are next, FR4 and pertinax are real problems..

what components do you favour in any one area, psu etc?

It so much depends on exact application and context, all common rules are "wrong".

Ciao T

 

[zanash]

And still we wait for any useful DIY information from Johnny !

Here's a question for johnny........I bow down, toss my coin into the font of wisdom .......and wait for an answer!

I make cables as a hobby, so can you tell me why copper sounds so bloated in the upper mid bass, and what would you do to make a more neutral cable ?

 

[dean.l]

Hi,

I'm not the J'ster....



N-Channel IGBT in a circlotron arrangement.



From experience, hardwiring really is best (though as circuit impedance goes down the distance reduces), Aralon and/or Teflon/Fibre boards are next, FR4 and pertinax are real problems..



It so much depends on exact application and context, all common rules are "wrong".

Ciao T

sorry 3d, that was to johnny as was everything else, sorry if it came accross being to you.

good answer though.

 

[ShinOBIWAN]

Hi,

Given your statement that you use PMC Monitors, why do you use speakers designed in direct contravention of the basic requirments to ensure a reasonably uncoloured reproduction of sound in acoustcially small rooms that have not extensivley "passivated" (in other words rooms that are not anechonic chambers and speakers with an excessively wide and variable dispersion)?

Do you not particulary like the way the actual recordings sound?

L8er T

Come on Thorsten.

I take offense to your pushy take on what you *think* a loudspeaker design should be to achieve *accuracy*.

Your statements are riddled with holes the size of my fist. I've challenged your views on DIYA before but I see your still peddling your myth.

Why do I take offense? Because I have explored plenty of avenues and have settled on a system that is the antithesis of what you consider accurate. The real kicker is that, objectively, its one of the most accurate systems on here. I'm quite sure you'll reply with a list of pointless dissections of my post and we'll go around in circles for a page maybe two and then you agree you have your method and I agree I have my mine and both are valid for certain needs blah blah blah.

So why don't you give it a rest.

If you really want to talk about accuracy, why not take a good look at the recordings - I'm betting that over 90% are mastered on systems that you would consider inaccurate and yet you suddenly consider that playing them back through your ideal accurate system makes the whole experience accurate? Forget it, with hifi you've got more variables than I ever care to go into and your idea's are no more valid than the rest so to say something is inaccurate is a bit full of it.

I find it particularly interesting that you talk of accuracy and you use dipoles!?

 

[3DSonics]

Hi,

Why do I take offense? Because I have explored plenty of avenues and have settled on a system that is the antithesis of what you consider accurate.

Which you are welcome to.

You and anyone else is welcome to like what they like.

If you like speakers with a DI varying from 0db to 16db between bass and treble that is fine with me.

Personal preference is simply that, personal preference. If you like a lot of reverb sauce added to your musical meal who am I to tell you should not have it?

However, truthfulness to the actual recording is another thing.

BTW, I use Dipoles because they have a by far less variable DI than conventional speakers and reduced room interaction. You should also be aware that due to the volume behind the driver and the basket opening each cone driver has a build in 2nd order lowpass on the rear response, usually somewhere between 500Hz and 2KHz, the drivers I use start rolling off towards the abck at around 800Hz IIRC (would need to check), so an octave above that frequency the speaker is very much a monopole....

L8er T

 

[dean.l]

in response to the cd thread (locked now so I will post it here) and johnny in general.

I will be honest, talking to johnny really doesn't bother me at all, he can say what he likes and should be allowed to do so, (so long as it is not uncalled for offensiveness, which it has been) it is up to me/you everybody else to choose whether to reply, so in my opinion we get what we deserve.

sorry to be blunt but if you really don't like it don't talk to him it really is that simple.

ps this is not directed at anybody in particular.

 

[3DSonics]

Hi,

sorry 3d, that was to johnny as was everything else, sorry if it came accross being to you.

No, I just thought I'll illustrate a constructive reply....

good answer though.

We try....

Ciao T

 

[Johnny]

Hi,

Johnny, you deliberatly altered your quote of my writings.

I suggest you take remidial action immediatly, as your actions consist legally speaking of libel. In the UK this is a prosecutable offense.

I suggest you consider remidial action.

Kind regards Thorsten

Which quote did I alter ?

I apologize if I have offended you and I hope we can settle any disputes amicably.

 

[Tenson]

I don't doubt what you say about di-poles being less room interactive as I know you are an empirical guy just as much as theoretical so will have real world experience to back that up.... but why are they less room interactive? I realise they have nulls at the sides, but they then just spew all that out the back instead (up to a point). What makes putting the sound out the back any less interactive with the room than out the sides? Do we presume that the listener has less room to the sides of their speaker than at the back?

I'm going OB for less (none) box colouration

 

[sastusbulbas]

This Meg RL901k what is the cost per pair, and have you auditioned it in small and medium rooms ?

I was wondering how the bass performance does in smaller locations ? I felt most large drivers benefited from room size and distance to get the lower frequency balance correct ? (I sort of felt coupled cavity had more leeway in room size and positioning?)

It looks like a nice option over the Tannoy DMT types with their Mid/treble horn colourations ?

 

[3DSonics]

Hi,

why are they less room interactive?

In the modal region of the room a dipole (velocity transducer) will maximally excite room modes when placed at the velocity maximum (middle of room) and minimally when placed at a velocity minimum (near walls/corners).

Compare that to a normal speaker which is a pressure transducer, which will maximally excite room modes in a pressure maximum (which is a velocity minimum) in other words near walls/corners while it will minimally excite room modes in a pressure minimum (velocity maximum) that is in the middle of the room.

As in acoustically small rooms speakers invariably end up near walls a dipole is preferable there.

Secondly, in the diffuse region of the room (usually above around 200Hz) a normal "HiFi" speaker will have a DI (directivity index, a measure how much sound the speaker sends into the room overall compared to the sound radiated towards the listener) starting at 0db (in other words sound is radiated everywhere) and increasing to well past 6db (meaning 6db less sound is radiated into the room compared to the sound radiated towards the listener) by the time we get to a few KHz.

This means the radiation pattern alters drastically in formant range of most musical instruments (Formants are overtones that are major contributors to the tone of the instrument, they "form" the tone) meaning that direct sound and reflected sound have very different timbres and that there is more room reverb at low formant frequencies than at higher formant frequencies.

If we compare a dipole, it starts with a DI of 4.8db and only increases to around 6db across the formant range, meaning reflected sounds and direct sound retain the same timbre and tonality, have the same amount of room reverb AND CRUCIALLY (unlike omnidirectional speakers which also make sure that the timbre is the same between reflected and direct sound) have much less room reverb than Omni's and related designs.

This is not to say that it is not possible to make good sounding conventional speakers, but it is much harder than to make a good sounding dipole or omnidirectional speaker.

As I noted before, my "ideal" speaker would actually be of an "adjustable pattern" type, allowing seperate adjustment of directivity in the sub 200Hz region (to minimise room interactions) and above 200Hz (to suit the recordings style and personal taste/preference/mood).

Ciao T

 

[3DSonics]

Hi,

This Meg RL901k what is the cost per pair?

£ 6000 plus VAT

and have you auditioned it in small and medium rooms ?

No, I have heard the non "K" RL-900 many times in such conditions (Control rooms), but the 901K I only heard at KMR Audio.

However, as the 901K is designed to deal with acoustic iussues in fairly small control rooms and aparently does that well....

This little bit of reading might be of use:

http://me-geithain.de/presse/ppeng/presseppeng.html

Ciao T

PS, relevant to my answer to Simon, the MEG "K" system produces a unidirectional sound souurce, which combines elements of velocity and pressure transduction and is thus somewhere between dipole and monopole bass, however it tends much more into the dipole direction....

 

[Johnny]

Hi,

Johnny, you deliberatly altered your quote of my writings.

I suggest you take remidial action immediatly, as your actions consist legally speaking of libel. In the UK this is a prosecutable offense.

I suggest you consider remidial action.

Kind regards Thorsten

Does anyone have any idea what this man is talking about ?

 

[dean.l]

I can't see anything at the moment *goes to look again*

3d?

 

[Johnny]

And still we wait for any useful DIY information from Johnny !

Here's a question for johnny........I bow down, toss my coin into the font of wisdom .......and wait for an answer!

I make cables as a hobby, so can you tell me why copper sounds so bloated in the upper mid bass, and what would you do to make a more neutral cable ?

What useful diy information ?

''No No No ......

you post your ideas here and then we comment or offer advice, not the other way round.''

is what you said to me.

you use silver instead of copper.It has a higher ratio of direct current to voltage, and you use the appropriate insulation with the correct permittivity.

However, there is no such thing as a neutral cable. A cable doesn't sound like anything. It only completes the circuit between say an amp and preamp, so it obviously depends on the two circuits.

 

[dean.l]

"there is no such thing as a neutral cable. A cable doesn't sound like anything"

what a silly statement.