Open source speaker project - Part II

Design Goal

  • Classic -Amp Friendly- Hi Sensitivity (92db+), Higher Bass Ext (f3 40-45Hz), Cabinet Size 60-80

    Votes: 18 17.8%
  • Classic -Bass Friendly- Deep Bass (f3 35-40Hz), Lower Sensitivity (88db+), Cabinet Size 80-110

    Votes: 10 9.9%
  • Classic XL -Amp and Bass Friendly- Hi Sensitivity (92db+), Deep Bass (f3 35-40Hz), Cabinet size 100+

    Votes: 12 11.9%
  • Tower -Amp Friendly- Hi Sensitivity (92db+), Higher Bass Ext (f3 40-45Hz), Cabinet Size 60-80

    Votes: 13 12.9%
  • Tower -Bass Friendly- Deep Bass (f3 35-40Hz), Lower Sensitivity (88db+) , Cabinet Size 80-110

    Votes: 21 20.8%
  • Tower XL -Amp and Bass Friendly- Hi Sensitivity (92db+), Deep Bass (f3 35-40Hz), Cabinet size 100+

    Votes: 27 26.7%

  • Total voters
    101
  • Poll closed .
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What you say is probably true, that is why we see so many tiny speaker projects that one or two people make with some of the popular ones being built by many. This however does not negate the need for a few large projects for the few that want them.
Indeed but are they suitable for group projects rather than personal projects? From the few you need to find enough people with sufficient design interest and/or sufficient build interest to form a group. Opting for a design with a high demand rather than one with low demand will increase the chances of this happening.
 
Last time I asked her about the looks of the new speakers I ended up covering them with sheets of "rotten" brass. Had to leave the brass in the garden for a few months to get the right level of oxidation. Aurichal | HiFi-Bau Brennwald

Wow, well done! You're on a different level then I, mine will ply boxes with milk paint. I will let the wife and kids pick the color.
 
Indeed but are they suitable for group projects rather than personal projects? From the few you need to find enough people with sufficient design interest and/or sufficient build interest to form a group. Opting for a design with a high demand rather than one with low demand will increase the chances of this happening.

You're always gonna be right on this one, I just want a giant speaker project and don't have the capabilities to design myself.
 
That was painful. I first tried some expensive "high quality" mounting adhesive from a shop that was recommended to me by a professional carpenter. That was crap, even ketchup would have been better. Then I tried the cheap stuff from the DIY store, worked perfectly.

I understand, one of those "I 'll never do that again" projects, but it was worth it, it's unique ;) IMO no matter how an speaker is good sounding and perfect, i can't just overlook the design and just enjoy it.
 
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It is not so much the size that strikes me as the cost to sound quality of using light resonating cones. If you need loud for party or PA use then it is a reasonable exchange for a low cost speaker but it seems a poor choice for high fidelity use in the home. Guess this is why there are so few commercial examples and the ones that do exist tend to come from the high end/audiophile end of the spectrum rather than the high fidelity.

Having said that, many modest sized inefficient speakers are unable to play transients cleanly at standard listening levels and so inefficiency is not particularly good either. If the objective is high fidelity in the home then where the optimum lies between the two has been well established although this shifts with the weighting given to size and bass extension.
 
Hmmm, do you have any robust evidence that light cones sound worse than heavier ones?
Less mass means less material for stiffness and less material for damping. The result is the onset of resonances at lower frequencies in the passband and usually with low levels of damping. This can be seen in the raggedness of an (adequately resolved) frequency response and heard in the typical sound of PA drivers.

These resonances are unwanted in high fidelity designs but they are not necessarily unwanted in high end designs for users of valve or ACA amps and similar. It depends on the objectives and type of speaker being designed which is far from clear at the moment.
 
Less mass means less material for stiffness and less material for damping.

Yes. And there is less mass that needs that stiffness and damping. It's a bit like a spring-mass system; it depens on the ratios of the mass, stiffness and damping.

The result is the onset of resonances at lower frequencies in the passband and usually with low levels of damping. This can be seen in the raggedness of an (adequately resolved) frequency response and heard in the typical sound of PA drivers.

I am not convinced (because of the above). I always thought that PA drivers tend to focus on cost vs. efficiency in terms of SPL per watt. Just compare the Thielle-Small parameters of typical PA and HiFi drivers and you'll get my point. PA drivers don't go as deep as HiFi drivers, but they go loud.

These resonances are unwanted in high fidelity designs but they are not necessarily unwanted in high end designs for users of valve or ACA amps and similar. It depends on the objectives and type of speaker being designed which is far from clear at the moment.

A good speaker design avoids resonances, no matter if the amplifier is big and strong or a whimpy tube amp (or an ACA). Within the scope of the Open Source Speaker, the 3-way approach will help a great deal to avoid resonances from the woofer doing bad things in the midrange because the woofer can be limited to the bass where cone breakup / resonances are absent.
 
Yes. And there is less mass that needs that stiffness and damping. It's a bit like a spring-mass system; it depens on the ratios of the mass, stiffness and damping.
It is a distributed rather than lumped system and the cone is only part of the mass that moves. High sensitivity drivers use the lightest cones that are viable and the resonances are a consequence. High fidelity drivers use stiffer cones with better damping if resonances fall within the passband or else use all the material to gain stiffness (e.g. metal cones) and push the lowest resonances above the passband. Exchanges better control of the resonances for reduced sensitivity.

I am not convinced (because of the above). I always thought that PA drivers tend to focus on cost vs. efficiency in terms of SPL per watt. Just compare the Thielle-Small parameters of typical PA and HiFi drivers and you'll get my point. PA drivers don't go as deep as HiFi drivers, but they go loud.

And the reason they go loud is...?

A good speaker design avoids resonances, no matter if the amplifier is big and strong or a whimpy tube amp (or an ACA).

A good design follows from meeting the design objectives and these vary with the type of speaker. People that choose valve amps or ACA amps are giving high fidelity a low weighting in favour of other things and, not surprisingly, this is reflected in the types of speakers they tend to favour. I linked to a diyaudio article on an example earlier.

Many excellent 3 way speakers have cones that resonate within the passband since this follows from opting for a soft rather than hard cone material.
 
So the poll is over.
  • 60% voted for a tower, 40% for a Monkey Box
  • Both camps (tower and monkey box) prefer a high-efficiency speaker
  • The Monkey Box camp prefers a smaller speaker, compromising bass extension
  • The tower camp prefers a big box without compromising bass. The runner up is the bass friendly speaker, with the amp friendly coming in last.

I think it's interesting that the Monkey Box camp has very different preferences than the tower camp (apart from the common trend for high-efficiency).

Now what? The obvious thing would be start designing a "Tower XL -Amp and Bass Friendly- Hi Sensitivity (92db+), Deep Bass (f3 35-40Hz), Cabinet size 100+", because that got the most votes. However, I have made so many towers that I'd prefer working on a Monkey Box for a change. Who would be interested in joining a design for a "Classic -Amp Friendly- Hi Sensitivity (92db+), Higher Bass Ext (f3 40-45Hz), Cabinet Size 60-80" box?
 
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So the poll is over.
  • 60% voted for a tower, 40% for a Monkey Box
  • Both camps (tower and monkey box) prefer a high-efficiency speaker
  • The Monkey Box camp prefers a smaller speaker, compromising bass extension
  • The tower camp prefers a big box without compromising bass. The runner up is the bass friendly speaker, with the amp friendly coming in last.

I think it's interesting that the Monkey Box camp has very different preferences than the tower camp (apart from the common trend for high-efficiency).

Now what? The obvious thing would be start designing a "Tower XL -Amp and Bass Friendly- Hi Sensitivity (92db+), Deep Bass (f3 35-40Hz), Cabinet size 100+", because that got the most votes. However, I have made so many towers that I'd prefer working on a Monkey Box for a change. Who would be interested in joining a design for a "Classic -Amp Friendly- Hi Sensitivity (92db+), Higher Bass Ext (f3 40-45Hz), Cabinet Size 60-80" box?

Me.
 
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