Introducing Directiva - An ASR open source platform speaker project

[sigbergaudio]

I think in your design though each driver plays a particular range right? resembling a proper 3-way instead of an MTM configuration.

It's 2.5-way (powered by three individual amplifier channels and active crossovers). And obviously not conventional MTM as such, since it's a coax + a midbass driver. But it would certainly fit the "small, loud and with a flat frequency response" definition.

 

[tuga]

I have question related to this one. I am fully conversed with cabinet design (as a commercial speaker designer) but I wondered if there is a website or a simple program that has a database of the drive units on the market and calculates the expected low frequency response guide of the speaker for vented and closed box cases. There are calculators using the TS parameters and outputs the f3 and possibly the FR plot (and one can use a calculator to do that) but it is a long process to look up the TS parameters and calculate each driver one by one.

A simple page where there is a drop down menu of drive units with a search function and the enclosure volume field. Select vented or closed box and see the FR plot. Wouldn't it be nice?

Dominique Pétoin's website, but it's in French:

Dôme acoustique : Page d'accueil d'un site sur la conception des baffles DIY

petoindominique.fr

 

[sarumbear]

How often do you need to search thousands? Maybe I don't understand the starting point. I don't treat all brands equally nor do some brands have accurate T/S params. So now I am down to a handful of manufacturers.

It seems to me that you are experienced in designing speakers. I am trying to find a tool for people who are not, yet. I am not asking help on how to use a program or how to do find a driver suitable for a loudspeaker design. I am trying to find a tool that I think will help a hobbyist who does not yet know the driver/enclosure interaction.

@HammerSandwich is spot on. Just update the vcad database with what you want. The window for typing new T/S params stays on top so you can enter it while manufacturer specs are open.

I guess it would be cool to setup some web scrapers for some manufacturers to keep VCAD up to date.

The open Loudspeaker Database lists 3806 drivers. It is as concise as it gets and the owner is willing to update it if you email them the driver data page link. However, even when doing a search by limiting the drives suitable for a 2-way bookshelf speaker using a rough TS value filter (as it is suggested above by various posters), you have 100 drivers available to choose. You still have a high hill to climb to decide which one to use.

Wouldn't it be nice if the selection is more precise by actually calculating the f3 (on the given volume and speaker type) and feeding the results to a favourite list. It can be done either at a web page or via common CSV export. You can then start adding preference data like price, availability, word-of-moth reviews. Once you reduce your selection to a manageable number of drivers it is possible to plot all of them on the same chart with option to enable disable each. This will allow you to speed your selection extremely.

I will approach the Loudspeaker Database owner to see if he is interested to implement my suggestion or he is willing to someway collaborate.

 

[sarumbear]

https://www.petoindominique.fr/php/mysql_multihp1.php

That is TS calculator. If you read my posts you may see that I am not looking for that.

 

[boXem]

That is TS calculator. If you read my posts you may see that I am not looking for that.

It is not a ts calculator. Heard about online translators?

 

[sarumbear]

It is not a ts calculator. Heard about online translators?

Why is everyone so rude? Of course I have translated it to English!

I have simply entered 40,000 - 50,000 to the Vb fields and click on the button. It came up empty. The default setting was to search all makes & models for all types of speakers for a 21cm diameter driver. It’s not logical to accept there is no 8” driver suitable for a 40-50 litre enclosure. If I am doing something wrong maybe you will be kind enough to show me my mistake?

Meanwhile, I cannot see f3.

 

[WesParker]

I hate to be that guy, but is there a summary of the final output of the build anywhere? I've read quite a bit of this thread, but haven't read all 42 pages yet.

 

[mdsimon2]

It is a bit hard to keep track of all the threads but the search below has all 4, you want the review thread.

https://www.audiosciencereview.com/...5445/&q=directiva&c[title_only]=1&o=relevance

Michael

 

[abdo123]

It's 2.5-way (powered by three individual amplifier channels and active crossovers). And obviously not conventional MTM as such, since it's a coax + a midbass driver. But it would certainly fit the "small, loud and with a flat frequency response" definition.

While your design would definitely fit the "small, loud, and with a flat frequency response" definition, a speaker with two Purifi woofers and 2* 500W of amplification would be small, LOUD and with a flat frequency response.

Edit: we're talking 116 dB @ 1m max output from 80Hz up, probably 122dB @ 1m max output from 300Hz up (if the tweeter can keep up) all below or about 1% THD.

 

[sigbergaudio]

While your design would definitely fit the "small, loud, and with a flat frequency response" definition, a speaker with two Purifi woofers and 2* 500W of amplification would be small, LOUD and with a flat frequency response.

Edit: we're talking 116 dB @ 1m max output from 80Hz up, probably 122dB @ 1m max output from 300Hz up (if the tweeter can keep up) all below or about 1% THD.

That would indeed be loud. Is that from one speaker? What is the maximum excursion you've simulated with to get that?

 

[abdo123]

That would indeed be loud. Is that from one speaker? What is the maximum excursion you've simulated with to get that?

I couldn't get the simulation to do 2 drivers without bringing the impedance down, so just add 6 dB to get the maximum output of 2 drivers. Looks like i was 3 dB off. maybe because i used the sensitivty @ 2.83V instead of @1W in my earlier calculations. it would still be an unbelievable amount of output for its size. I'm also not sure if this simulation takes into consideration baffle-step loss, my guess is that it doesn't.

 

[sigbergaudio]

I couldn't get the simulation to do 2 drivers without bringing the impedance down, so just add 6 dB to get the maximum output of 2 drivers. Looks like i was 3 dB off. maybe because i used the sensitivty @ 2.83V instead of @1W in my earlier calculations. it would still be an unbelievable amount of output for its size. I'm also not sure if this simulation takes into consideration baffle-step loss, my guess is that it doesn't.
View attachment 157611

I don't think you will have 1% THD at 10mm excursion either, if I'm not mistaken I saw a review where the actual linear xmax was 6.9mm or something on this driver? And at that point you're often already way higher than 1%.

EDIT: Ah, it's the W04. That's not even rated at more than 5.9 mm xmax. Your simulation is over 10mm.

 

[abdo123]

EDIT: Ah, it's the W04. That's not even rated at more than 5.9 mm xmax. Your simulation is over 10mm.

I don't think you will have 1% THD at 10mm excursion either, if I'm not mistaken I saw a review where the actual linear xmax was 6.9mm or something on this driver? And at that point you're often already way higher than 1%.

I ... don't believe you ?

 

[sigbergaudio]

View attachment 157617

I ... don't believe you ?

Sorry, misunderstood which driver you were considering to use. If I understood you correctly you were looking to create something intended for separate subwoofers(?) since you talked about 80hz, but I may have misunderstood that as well. If that were indeed the case, I would choose drivers more suited for midbass, and with much higher sensitivity than this so you don't have to worry about the cabinets literally catching fire from all the power you have to throw at them, especially if you're looking to create very small cabinets as well.

 

[fluid]

I ... don't believe you ?

Erin Klippel tested the 6.5" Purifi and the compliance was the limiting factor at 6.9mm excursion for 10% thd. The excursion is needed to produce lower frequencies at the same level which is why the thd takes off there.

 

[abdo123]

Erin Klippel tested the 6.5" Purifi and the compliance was the limiting factor at 6.9mm excursion for 10% thd. The excursion is needed to produce lower frequencies at the same level which is why the thd takes off there.

are we reading the same review?

Because the THD graph is missing

But the parting thoughts say this

This is the best speaker I have tested (I don’t have the same distortion data for the Scan 18wu I mentioned above). An incredibly low 1% THD above 70Hz at 100dB output!

 

[Juhazi]

Original source has gif images of distortion

Purifi Audio PTT6.5W04-01A 6.5 Inch Woofer Review

Purifi Audio PTT6.5W04-01A 6.5 Inch Woofer Review

www.erinsaudiocorner.com

 

[abdo123]

Original source has gif images of distortion

Purifi Audio PTT6.5W04-01A 6.5 Inch Woofer Review

Purifi Audio PTT6.5W04-01A 6.5 Inch Woofer Review

www.erinsaudiocorner.com

I still can't see the graphs, @hardisj could you please have a look at it?

 

[sigbergaudio]

I still can't see the graphs, @hardisj could you please have a look at it?

The THD graph is animated, it hits the 1%@100hz at around 100dB. So 106dB@100hz with two drivers is probably roughly accurate.
Also: "this drive unit’s linear excursion is limited to 6.9mm due to exceeding the Cms displacement limit of 75% for the distortion limit of 10%."

 

[abdo123]

The THD graph is animated, it hits the 1%@100hz at around 100dB. So 106dB@100hz with two drivers is probably roughly accurate.
Also: "this drive unit’s linear excursion is limited to 6.9mm due to exceeding the Cms displacement limit of 75% for the distortion limit of 10%."

thanks for the input, I guess i was the one mistaken, I apologize.

If we plug in Hypex F253 values ( ~6dB louder than Amir's 96 dB measurements, staying somewhat strictly in linear excursion limits) we would have 110 dB max output 300Hz and up (one driver, 116 dB for two). The Low frequency behavior would be LR 24db/oct at 80 Hz, however values are likely signficantly lower due to baffle step loss. It looks like I over-estimated the driver a bit, my mistake. you mentioned that there would be better choices for a LR 24db/oct at 80 Hz speaker. Can you mention them? Would love to run some simulations.