Maybe I missed it, but why do you include a mid reflex tube?
It will introduce more group delay and eventzal port resonances, considerig the big port shown in the rendering.
Or is it an aperiodic dampened vent?
It is a a fairly low resonance frequency (50Hz) well below the main frequency range this unit is responsible for (approximately 250 to 3k tbd) optionally stuffed as an aperiodic dampened vent indeed and that gives these units some breathing space and will sound smoother. (In my previous design I didn’t stuff the port and sounds fantastic)
Agree active for the woofer is the Way to go (though passive Can Sound fantastic aswell).
I was curious to know comparison, but guess we wont get it this time 🙂
I myself think Sound would benefit from some loss/resistance with passive components in the chain with Hypex Fusion if running fullrange. This is feeling and not knowledge.
Another update as the project is moving slowly due to holidays and the woodshop moving location.
We have been working on some details as the basic structure is defined.
The Plate-amp gets a custom heatsink. It has 2 3-pole screw terminals where a bridge between two crews enables the loop of a speaker terminal into the high level input of the ams, and removing it is used when the XLR input is selected.
Two banana sockets between the terminals are connected to the output of the plate amp so you can dial in the the gain of the plate amp by measuring with an AC volt meter (and get back to that value when the input adjustment attenuator is changed)
This is a picture of the plate amp.
We also defined the aluminum base and stainless steel feet.
Based on the finite elemente feet we decided to make them custom (many variations are available on chinese websites) as none were exactly what we need. Making 16 pieces made the price very acceptable.
The feet cylinder sits in a 10mm cavity of the base extensions and therefore there is some adjustments possible without the cylinder edge is will become visible. The Cylinder and the base edge are connected via an M10 bolt that is fixed to the Cylinder of the stainless steel feet.
Here the inside of the feet:
I plan to make the walnut side panels as separate 90mm high sheets (18mm thick) and mount them on the HDF inner enclosure with 3mm gaps between them. These gaps will be filled with a special kit that is used for teak boat decks.
So next is ordering the amp plate, base and feet so we can start assembling these. Next month the MDF/HDF inside will be CNC cut and we can assemble these then and order the aluminium front and back,
Here some more pictures of the final (inside) design
The green sheets will be some sort of (solid) rubber like EPDM to reduce the stress on the metal rods when temperature changes.
Take care Peter
We have been working on some details as the basic structure is defined.
The Plate-amp gets a custom heatsink. It has 2 3-pole screw terminals where a bridge between two crews enables the loop of a speaker terminal into the high level input of the ams, and removing it is used when the XLR input is selected.
Two banana sockets between the terminals are connected to the output of the plate amp so you can dial in the the gain of the plate amp by measuring with an AC volt meter (and get back to that value when the input adjustment attenuator is changed)
This is a picture of the plate amp.
We also defined the aluminum base and stainless steel feet.
Based on the finite elemente feet we decided to make them custom (many variations are available on chinese websites) as none were exactly what we need. Making 16 pieces made the price very acceptable.
The feet cylinder sits in a 10mm cavity of the base extensions and therefore there is some adjustments possible without the cylinder edge is will become visible. The Cylinder and the base edge are connected via an M10 bolt that is fixed to the Cylinder of the stainless steel feet.
Here the inside of the feet:
I plan to make the walnut side panels as separate 90mm high sheets (18mm thick) and mount them on the HDF inner enclosure with 3mm gaps between them. These gaps will be filled with a special kit that is used for teak boat decks.
So next is ordering the amp plate, base and feet so we can start assembling these. Next month the MDF/HDF inside will be CNC cut and we can assemble these then and order the aluminium front and back,
Here some more pictures of the final (inside) design
The green sheets will be some sort of (solid) rubber like EPDM to reduce the stress on the metal rods when temperature changes.
Take care Peter
Hi Forum,
The building begins .... at last
here the first dry fitting session
the raw internal bracing
after cutting out the CNC holes and rounding the edges
More to follow soon.
Cheers,
Peter
The building begins .... at last
here the first dry fitting session
the raw internal bracing
after cutting out the CNC holes and rounding the edges
More to follow soon.
Cheers,
Peter
@PSchut Looks nice!
Make sure to add a coil to that bottom woofer creating a 1st order rolloff……the distance from it to your top midrange is too far……..you’ll wind up with a downward facing lobe that will be pretty severe in the mid to far field.
Make sure to add a coil to that bottom woofer creating a 1st order rolloff……the distance from it to your top midrange is too far……..you’ll wind up with a downward facing lobe that will be pretty severe in the mid to far field.
We will need to check that, but the two woofers wil be in parallel and the crossover frequency will be around 150Hz. As this is done by the Hypex module a 4th order 24dB/oct is possible.
As it looks now an external active filter (in front of the power amp driving MF/HF) seems the way to go as filtering the two midrange units (@2,7 ohm Re and a resonance frequency peak at around 80Hz) will be a challenge in execution and cost. The preferred capacitor (270uF Silver/gold/oil) is around €700
As it looks now an external active filter (in front of the power amp driving MF/HF) seems the way to go as filtering the two midrange units (@2,7 ohm Re and a resonance frequency peak at around 80Hz) will be a challenge in execution and cost. The preferred capacitor (270uF Silver/gold/oil) is around €700
No Finsa Compac plus HDF (1100kg/m3) way stronger than valcromat
Another update:
We started building the inner enclosure.
Adding felt to the parts that cannot be reached later.
The first enclosure in clamps
The amp plates and heatsink (will be sand blasted and anodized)
The stainless steel feet
The base machined out of a solid billet (will be sand blasted and anodized)
And the Hypex plate amp arrived .......
So we are progressing.
Till next time.
Peter
We started building the inner enclosure.
Adding felt to the parts that cannot be reached later.
The first enclosure in clamps
The amp plates and heatsink (will be sand blasted and anodized)
The stainless steel feet
The base machined out of a solid billet (will be sand blasted and anodized)
And the Hypex plate amp arrived .......
So we are progressing.
Till next time.
Peter
May I enquire about the reason for that? Imho that stuff doesn’t add anything to an enclosure, since the frequencies it is effective for won’t be inside the enclosure anyway.
Most absorbing material doesn’t work for the lowest frequencies. But depending on the crossover frequency and slope a woofer produces frequencies that sits in the range this stuff starts to work. There will also be another layer of damping material (like wool for the midrange and Akotherm Basic D20 for the LF part)
Some tests proved that the material I initially wanted to use (technocell) actually decreases the volume of the enclosure while this felt and Akotherm increase the volume.
Technocell works better to isolate a room from another than actually absorbing the sound.
Some tests proved that the material I initially wanted to use (technocell) actually decreases the volume of the enclosure while this felt and Akotherm increase the volume.
Technocell works better to isolate a room from another than actually absorbing the sound.
Pardon me for the hijack, but I feel I have to debunk some myths about felt… Now this is probably best case scenario, since stemming from a felt supplier.
You are right that low frequencies are hard to tame. In a typical enclosure however, we’re fighting mid frequencies from 150Hz to about 2k max in case of a 2-way. That is home territory for the usual >50mm foam or wool solutions.
No worries marbakk, that is why this forum should be used, share, challenge and learn.
I must admit I was puzzled by the graphs and real results. Influenced by Troels Gravensen who from a DIY point of view has the best website and although I don't like everything he does he has an impressive state of speakers.
When I used tecnocell (and sorry it is called Acousticcell in English but tecnocell in Dutch) in my original design I had the idea that it lowered the volume of the enclosure instead of increasing. So the resonance frequency went up.
Discussing that with a specialist from Merford (the supplier of all sorts of damping and isolation material) he said that to absorb the lower frequency in a speaker enclosure the material should not be too dense as reflections can occur and that is fine to isolate for instance an enclosure to keep the sound inside (like a noisy compressor) but will still scatter.
A much better material is Akotherm and use it as a filling. Troels does something similar by combining Bitumen pads, felt and a Polyester wool.
So for this we decided to do the same, but with less bitumen as a combination of 15mm MDF + 13mm HDF and 20mm Walnut (+ 40mm Aluminium front panels) would be rigid enough and is only used on some internal panels.
A full layer of felt (just recycled cloth and not really felt) on all sides and then this akotherm loosely in the gaps of all the braces is the best of both worlds.
The midrange enclosure will be felt and wool or Twaron.
Please take a look at the graphs provided by the links I shared, it is very interesting.
here you see in real life what the 3D renders looked like in earlier pages of this tread.
By the way. I used the Finsa Compac Plus as internal braces as it extremely rigid, cuts very clean and sharp and uses less volume than plan MDF.
This structure will get a full layer of that material on the outside as well. Compac Plus
take care, Peter
I must admit I was puzzled by the graphs and real results. Influenced by Troels Gravensen who from a DIY point of view has the best website and although I don't like everything he does he has an impressive state of speakers.
When I used tecnocell (and sorry it is called Acousticcell in English but tecnocell in Dutch) in my original design I had the idea that it lowered the volume of the enclosure instead of increasing. So the resonance frequency went up.
Discussing that with a specialist from Merford (the supplier of all sorts of damping and isolation material) he said that to absorb the lower frequency in a speaker enclosure the material should not be too dense as reflections can occur and that is fine to isolate for instance an enclosure to keep the sound inside (like a noisy compressor) but will still scatter.
A much better material is Akotherm and use it as a filling. Troels does something similar by combining Bitumen pads, felt and a Polyester wool.
So for this we decided to do the same, but with less bitumen as a combination of 15mm MDF + 13mm HDF and 20mm Walnut (+ 40mm Aluminium front panels) would be rigid enough and is only used on some internal panels.
A full layer of felt (just recycled cloth and not really felt) on all sides and then this akotherm loosely in the gaps of all the braces is the best of both worlds.
The midrange enclosure will be felt and wool or Twaron.
Please take a look at the graphs provided by the links I shared, it is very interesting.
here you see in real life what the 3D renders looked like in earlier pages of this tread.
By the way. I used the Finsa Compac Plus as internal braces as it extremely rigid, cuts very clean and sharp and uses less volume than plan MDF.
This structure will get a full layer of that material on the outside as well. Compac Plus
take care, Peter
This material looks very interesting. Is it denser than MDF? Looks like plastic but is it a mix with wood fiber like some hybrid decking? I don't suppose it's available outside of Europe... I wonder whether there's anything comparable in Canada?
I agree with mikessi that it looks interesting. What is the price and from where do you procure it? I could not find a quote on their website
We payed 46 euro per square meter and use one sheet of 3,7m2 per 2 speakers
I've had really good luck using neoprene foam sheet gaskets under the midrange drivers and woofers, fastened with floating threaded inserts to decouple the chassis. It makes a massive difference in vibrational transmission between the chassis and front baffle, cleaning up the lower midrange without excessively stiff and unnecessarily thick cabinet walls. The trouble with many larger floor standing speaker designs is the panel resonances landing right around the 200 - 800 hz range. Thats right in the meat of lower midrange and will ruin neutrality in that range.
Sandwiched higher density neoprene foam with MDF side panels creates a highly dampening composite material. I started using this on all my slimmer floor standing designs with great success.
Sandwiched higher density neoprene foam with MDF side panels creates a highly dampening composite material. I started using this on all my slimmer floor standing designs with great success.