You mean wintermute's? Yes it's a great background reader.
You think I should just append to his thread, and finish it up (with his permission, of course)
My idea was just to document a recent design.
I'm not going to do a construction/build thread full of beautiful construction photos.
This will be a design process thread.
You think I should just append to his thread, and finish it up (with his permission, of course)
My idea was just to document a recent design.
I'm not going to do a construction/build thread full of beautiful construction photos.
This will be a design process thread.
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Yes no point reinventing the wheel- mine will follow Kimmo/VituixCAD2's Checklist:There has got to be numerous threads here already. So how do you make this one stand out?? There are general rules to follow but there are differences in technique as well as methods so I don't think there is any one best solution. Depends on what tools you have access too.
Rob
Checklist for designing a loudspeaker
Investigate acoustic parameters, dimensions, materials and speaker placement possibilities of the listening room. It is wise to fix issues of bad environment (the room) first rather than trying to handle everything with massive and complex speaker design.Basic engineering
- Decide acoustic design; type and amount of directivity, radiator types, ways, driver size and count.
- Estimate possible sensitivity range and crossover frequency ranges.
- Select initial drivers and directivity components to reach previous targets
- Simulate low frequency radiators with Enclosure tool
- Simulate baffle diffraction and export cabinet impact response
- Design the cabinet.
Construction
- Build flexible prototype or final cabinet depending on uncertainties in the design
- Connect temporary cables to individual drivers (or driver groups) for acoustical and electrical measurements.
Measurements
- Prepare turning table for polar response measurements. Manual turning table is easy to make and fast to use for example with Clio 10-12 or ARTA 1.9 or REW 5.20 beta.
- Choose directions for off-axis measurements. You are not forced to measure full or half circle around the speaker with constant 5 or 10 deg steps, but it is recommended to get correct power & DI result and simulate reflections and rotate/tilt drivers. Simulation is possible with less than 10 directions per axis. Don't waste your chance to get all measured data at once. There is no need to measure vertical axis if vertical measurement would be "equal enough" to horizontal measurement. For example full range driver in the center of square box is symmetrical in both directions.
- Measure polar response of each driver (or driver group) as far field measurement. Use equal off-axis angles for all drivers, though not mandatory. Don't let measuring program to corrupt timing: use semi-dual (or full dual) channel measurement to lock time reference to mic capsule. Measure time-windowed responses from the same or at least known/measured distance to the reference point to maintain common time reference with different ways & drivers. Note! Filenames should include plane (hor/ver) and angle in degrees.
- Measure near field responses of midrange and woofer cone(s) and port(s) if anechoic environment is not available. Arrange radiator to half space to avoid baffle loss. Some amount of baffle loss exists with small cabinets in full space even if measurement distance is less than 8 mm. Use the same output voltage with far field measurement (if possible without clipping or excessive distortion) to help merging of near field and far field measurements.
- Measure impedance responses of each driver or driver group.
Merge and manipulate response data
- Merge far field and near field responses with Merger tool if you didn't measure low frequency radiators (<300 Hz) from far field in anechoic environment.
- Include cabinet impact response (from diffraction simulator) in near field responses.
- Export merged responses as separate txt/frd-files.
Simulate loudspeaker with VituixCAD
- Create new empty project and enter Description
- Add driver types in Drivers tab
- Enter driver names, nominal SPL and Z
- Insert frequency responses. Adjust scaling, delay, polarity and smoothing if needed.
- Insert impedance response. Adjust scaling if needed.
- Outline rough targets for axial response and power response
- Outline rough targets for axial responses per driver
- Design the crossover
- Insert filter blocks
- Adjust parameter/component values of filter blocks manually
- Play with circuit topologies and parameter/component values until axial response, power response, directivity index, polar responses and impedance response meet your targets.
- Save project periodically. Save most promising intermediate results to project file or crossover variant.
Build and install crossover
Quality control
Mandatory QC-measurements- Angled measurements in horizontal and vertical planes, at least 30 deg steps
- Impedance response
- Excess group delay
- Harmonic distortion
- Intermodulation distortion
- Compression
- Acoustic compatibility to your listening room; room response, clarity parameters.
If you are not satisfied return to drawing board.
Reference:
https://kimmosaunisto.net/Software/...20.html#Checklist_for_designing_a_loudspeaker
So using concrete examples and more hand-holding that Kimmo's great (but broad) guidance...
For instance, Open Source Monkey Box is a great speaker, but does the thread allow a reader to design their own? I think that's my goal of documenting best practices in 21st C...
Yeah Kimmo's guide is .. blunt. It's taken me over a year to grasp every corner of VCAD and now I read the guide it all makes sense, but I remember reading it the first time thinking "what the ....."
I vote for finishing Wintermutes thread.
No doubt VCAD and REW (or ARTA) are the two best software tools for the job.
Essential tools for designing and measuring a 2-way bookshelf loudspeaker - Computer (pref. laptop), REW or ARTA, VCAD, 2 channel soundcard with 48V mic input (focusrite solo or similar), 48V condenser mic (soundworks XREF20, Dayton EMM6 or similar), Mic Stand, Turntable, stereo power amplifier or integrated amplifier, Dayton DATS or similar, a garage or empty room with at least 4m x 5m x 2.4m space, cables to suit as XLR or TRS to RCA etc.
I vote for finishing Wintermutes thread.
No doubt VCAD and REW (or ARTA) are the two best software tools for the job.
Essential tools for designing and measuring a 2-way bookshelf loudspeaker - Computer (pref. laptop), REW or ARTA, VCAD, 2 channel soundcard with 48V mic input (focusrite solo or similar), 48V condenser mic (soundworks XREF20, Dayton EMM6 or similar), Mic Stand, Turntable, stereo power amplifier or integrated amplifier, Dayton DATS or similar, a garage or empty room with at least 4m x 5m x 2.4m space, cables to suit as XLR or TRS to RCA etc.
This particular method of measurement is a road that many are looking to go down.
There is a discussion thread for Wintermute's thread here - https://www.diyaudio.com/community/...peaker-from-scratch-discussion-thread.332689/
If you make any relevant posts in that thread they can always be collected into a thread at any time later, and edited as needed.
There is a discussion thread for Wintermute's thread here - https://www.diyaudio.com/community/...peaker-from-scratch-discussion-thread.332689/
If you make any relevant posts in that thread they can always be collected into a thread at any time later, and edited as needed.
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Tick tick tick tick-
These are the prerequisites. Hopefully getting as many people up to speed to this as a bare minimum.
I'm going to document a 3 way box speaker 90+dB/2.83V.
Other essentials IMHO
- Excess group delay
- Harmonic distortion
- Intermodulation distortion
- Compression
- Acoustic compatibility to your listening room; room response, clarity parameters.
Prototyping with DSP
Converting to one box solution (aka passive crossover version)
DRC
Desirable
Not sure if I'm going to cover or document advanced topics like:
Optimal cabinet shapes, constant or controlled directivity
CLD, deadening and damping
integration of subwoofers ie. 4 way
dipoles
(have built them all, just not sure of the scope of the thread- might need it's own thread)
People are always interested in modern drivers Purifi, but I'm not sure if I'll lose too many readers due to concerns of price.
Or should I use good (but NLA) drivers to encourage readers to start their own journey... (learn how to choose your own drivers based on your budgeet)
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I look forward to how this goes!
I'd like the guide to touch on a few things I don't grasp very well and haven't seen many guides:
phase; its tweaking in a passive crossover, solutions for time alignment
aligning acoustic centers and lobing
bafflestep loss and solutions for addressing it
how to size and build a midrange compartment in a 3 way
Thanks.
I'd like the guide to touch on a few things I don't grasp very well and haven't seen many guides:
phase; its tweaking in a passive crossover, solutions for time alignment
aligning acoustic centers and lobing
bafflestep loss and solutions for addressing it
how to size and build a midrange compartment in a 3 way
Thanks.
I applaud your effort. It is a big job, but not so big that it is unmanageable.
Since this will be a design process thread, it does not really matter what drivers you select as your example, in my opinion... as long as they are reasonably conventional. Purifi are very high quality, but still conventional drivers. Everything you present, process wise, should carry over to other drivers, whether high end or low priced...
j.
Since this will be a design process thread, it does not really matter what drivers you select as your example, in my opinion... as long as they are reasonably conventional. Purifi are very high quality, but still conventional drivers. Everything you present, process wise, should carry over to other drivers, whether high end or low priced...
j.
Hello
The drivers are independent of the actual design process as you go through the motions. The possible limitations that driver selection could influence would be distortion levels, power compression and 1 watt SPL as examples. Independent of adjusting for these parameters for the targeted design it should be an almost identical design process.
Drivers do matter depending on what you want. You are not going to get 98db SPL 1 watt out of $10 drivers. As long as you document this well there is no reason another person could not follow along with there own driver set with adjustments depending on differences between the driver sets.
Rob
Good starting place. Buy woofers, measure, simulate, build, measure and do it over and over with a goal of understanding things more and more.. Valuable insight will be gained from the experience!
All you need is a good box program. Win ISD is free. I use Bassbox Pro which gives you more options. All you really need is internal volume and port length and diameter for a reflex enclosure. Many have a library of loaded T/S parameters for the drivers or you can just enter them for your specific drivers. If you already have the wood working skills using these programs is not all that hard to learn . The actual box build is the hardest part.
Rob
Its time to move on from Win ISDAll you need is a good box program. Win ISD is free. I use Bassbox Pro which gives you more options. All you really need is internal volume and port length and diameter for a reflex enclosure. Many have a library of loaded T/S parameters for the drivers or you can just enter them for your specific drivers. If you already have the wood working skills using these programs is not all that hard to learn . The actual box build is the hardest part.
Rob
. VituixCAD has enclosure modeling.
All you need is a good box program. Win ISD is free. I use Bassbox Pro which gives you more options. All you really need is internal volume and port length and diameter for a reflex enclosure. Many have a library of loaded T/S parameters for the drivers or you can just enter them for your specific drivers. If you already have the wood working skills using these programs is not all that hard to learn . The actual box build is the hardest part.
Rob
It depends on your background and skillset. For some people building boxes is a walk in the park- think carpenter, handyman, builder.
but using SpeaD, or ReverseSpeaD, BassBox Pro, Unibox, Speakerboxlite is a challenge.
I needed some hand holding by young fellow mainframe99 recently getting some 3D printing going... but I've built about a dozen speaker boxes...