Who are you??

[gnarly]

As a hobby, I design and build speakers, and am deep into the DSP processing that goes with them.

Got started with building others' designs:
Tom Danley's Labhorn subs
Peter Morris's mains, PM90/60.

Then got the design bug too.
10 modular PA trap boxes, built to splay/array.
8 sub boxes; 2 sealed, 2 ported, 2 double ported push-pull, 2 more ported.
2 Murphy corner line arrays.
2 CBT line arrays.
15" proaudio coaxial, ported.
A few concentric-rings, focused array prototypes (the only boxes I've ever considered outright failures.)
A dodecahedron.
Trying a number of larger commercial horns made for compression drivers.
Approx a dozen versions of synergies/unities/MEHs, all for use with a sub(s). 3 boxes of the latest 4-way version for LCR, 2 stereo pairs of prior 3-way versions, 2-3 single older boxes too good to scrap, & the rest scrapped.

I consider all the boxes to have been at least good. Most have been excellent, to downright extraordinary successes if i may say so myself. (again, with the exception of the focused array types.)
I think a huge/key part of the success has been from using a standard linear phase tuning process on all of them, shooting for flat mag and phase

 

[Glint]

I buy retail gear (second hand) and tinker/refurbish it...pretty decent with a soldering iron, etc, nor do I really fully understand the circuits I'm fixing up, not yet doing full DIY builds though, only a matter of time

 

[Newman]

2 Murphy corner line arrays.
2 CBT line arrays

Which of these measured better?

 

[Andysu]

as young projectionist with UCI cinemas tower park 10 plex , 1989/1990 i came up with designing idea of delightful discovery to improving the stereo surrounds common on 70mm at another cinema Empire Licester square in THX , back then . oh still is today less uncommon with only few cinemas geared up for it . i was frusrtaed with centre-phantom that floated between the left-half right-half surrounds . while listening to the booth monitor at tower park , during late afternoon i came up with that idea that is "!dolby surround ex" . i didn't put the idea into pratcice till 1998 when got first millennium dts 2,4,6 decoder with a yamaha DSR70Pro connected to the stereo surrounds with x9 speakers for surrounds in my home cinema room , two each side and five on the back wall for CBS centre back surround . set up using basic pink noise from the dts demo test disc full-range played "goldeneye" 1995 dts THX laserdisc . wow , wow , oh , it actually works . now i have that centre phantom sounding on New channel of surround arrays behind me .
i made mistake sharing my idea with dolby labs , new york , spoke to guy called , eric kristofferson , who kept bragging he's a movie actor of same "kristofferson" for few minutes . now i made the phone call to , new york as uk offices was closed and this was 9pm uk time and call to new york would be cheaper than dolby labs san francisco main head offices . i was on the phone 30 mins . the guy said that is very interesting and why five speakers on the back wall ? well that was the only amount i gathered from closed down shopping centre small box 8" full-range pa speakers with transformer that i removed . so five on back wall , when usually it's six surrounds on back wall .

so i ended the phone call and 1999 i saw my idea in a home cinema magazine and was red faced pissed hissed mighty off and now i simply hate dolby labs as they are nothing more than backstabbers . i should have patented the idea . i been saying same story now since 1999 . anyway least i came up with the idea had it up and running nearly 2 years before consumer home cinema had the watered down version of dolby digital ex , that doesn't included the extra rear matrix surround channel . i also used that same output for 2 weeks with mismatched speakers dangling from the ceiling around 2000 nearly 2 years before dolby labs used it for "we where solders" "sonic whole overhead surround" ,

dolby labs today stiff around forums like dogs looking for new idea they can steal .

 

[Waxx]

Most speakers used now in my house are my own design and build, amps are a mix of diy-build designs of others and bought, electronics are mostly bought but sometimes modded. The speakers i did not build myself are my old trusted Goodman Mezzo SL's (the first higher end speakers i owned and a kind of reference for me) and a few old philips speakers that i use in my kitchen to listen to the radio when cooking (so in a noisy envirroment). I have no formal education in engineering or so, but do study the subject for 25 years now and know quiet a bit and i like to mess arround with speakers and speaker design. They are my main focus.

I'm a former dj & music producer (very underground styles) and sound engineer (i did that untill my back killed that carreer), now i work as ICT system engineer (also without degree, but with diy knowledge (aka study it yourself) and a good reputation) and as radio broadcaster on a local station. In my dj and sound engineer time i did also do a lot of basic repairs, of speakers and electronics, and i still do that from time to time (more as hobby that earns a little than as job). I'm also a bit trading vintage gear when i find opportunities. But IT is my real job now, the rest is hobby.

 

[gnarly]

Which of these measured better?

The CBT's measured better without any processing. Took considerably less EQ work to bring to flat.
After processing, measurements looked much more alike than not.

I should probably offer some caveats about their processed measurements though.

CEA2034 type measurements, Klippel NFS etc, I don't think have as much meaning for the line arrays as they do for the standard type speakers Amir and Erin usually test.
The lines have so much interdependency in the vertical plane, with both themselves and with the room, it's hard to separate out quasi-anechoic response from in-room response, and even hard to define where on-axis is vertically (especially for the straight lines)
For example, the straight line's image center moves up and down the line along with listener's ear height. Whereas the CBT's apparent acoustic center stays closer to the same distance off the floor.
Also, the CBT's were much more immune to room placement, than the straight lines.

2nd caveat is that for HF/VHF, i think it is necessary to look at the frequency response coherence. The normal transfer magnitude response doesn't tell the whole story as to how it will sound. The frequency response magnitude may look very good, but if it has low coherence, it will sound a little smoothed over, a little less defined, compared to high coherence. My experience ymmv.

I used the same set of 24 TC9 3" drivers for both type arrays, so it was a lot of fun making somewhat near apples-to-apples comparisons.
Also made a number of beam steering, frequency shading, and CBT emulation experiments, with the straight lines.
Had the drivers separated into 6 active sections of 4 drivers each.

here's a pict of them...

 

[Wolf]

I roll my own speaker designs, for over 20 years now. I'm well past the 100 mark.
I have built or assembled many a cable.
I've built amps from modules or other's designs.

 

[dc655321]

i think it is necessary to look at the frequency response coherence.

Define coherence in this context, please.

 

[gnarly]

Define coherence in this context, please.

Sure, here's snips from the ARTA and Smaart manuals...

From ARTA: 3.2 Dual Channel System with Continuous Noise Excitation
The coherence function is a measure of the proportion of the power in y that is due to linear operations on the signal x. When estimating the transfer function, the coherence function is a useful check on the quality of data used. The maximum value of coherence is 1. In ARTA you can display the coherence, so it is possible to check the coherence associated with "double channel" measurements. Practically, we must have γ2 close to 1 to ensure the good estimation, but we must keep in mind that coherence has a sense only if the number of averages is greater than 1.

From Smaart:
Coherence
Coherence is a statistical estimation of the causality or linearity between the reference and measurement signals in a transfer function measurement. Coherence does a good job of detecting
contamination of the measurement signal by unrelated signals such as background noise and reverberation, and it is sensitive to timing mismatches as well. We use it in Smaart to gauge the quality of transfer
function measurement data, frequency by frequency, in real time. Additionally, since the same factors
that affect coherence (mainly noise and reverberation) also affect speech intelligibility, the coherence
trace can also give you a sense of how intelligible a system is.
The coherence calculation essentially asks the question, “How confident can we be that what we are
seeing in the measurement signal at this frequency was caused by the reference signal?” The answer is a
number between zero and one, which Smaart displays as a percentage. A value of 100% indicates perfect correlation between the two signals and zero means there is no discernable relationship between
them.
In nuts and bolts terms, coherence works by comparing the cross-spectrum (the frequency-domain
representation of a cross-correlation) of the reference and measurement signals to the product of their
averaged power spectra. That means it must be calculated across multiple readings of the two signals in
order to be meaningful. If you looked at just a single reading of any pair of signals, coherence would
always be 100% for all frequencies, and so the feature turns itself off when averaging is not in use.
Figure 93: The coherence trace is plotted on scale of 0-100 in the upper half (or quarter) of the magnitude graph.

On the lines, where multiple drivers are producing the same HF/VHF frequencies, and are spaced far enough apart to break a continuous ribbon or planar type summation,
I see that coherence drops more and more above some particular transition frequency.
Which simply means multiple arrivals of the same frequencies; and is what I think causes the less defined sound (vs a single good HF/VHF driver.)

 

[dc655321]

coherence works by comparing the cross-spectrum (the frequency-domain
representation of a cross-correlation) of the reference and measurement signals to the product of their
averaged power spectra.

That’s the definition I was looking for. Thx.
Or here.

 

[EJ3]

more votes will not give you Statistical validity - you will need to read up on polling techniques for that

Ya know... Statistical validity and that.

I took that statement as him having a great sense of humor.

 

[EJ3]

I'm curious for how many ASR members design and/or build their own audio gear (i.e., audio electronics and speakers/headphones). I hope you'll satisfy my curiosity by responding to the poll here.

I've chosen to limit the poll to audio gear. If you build your own furniture for housing your audio gear or build your own home theatre, I think that's really cool, but - to me - that's more in the realm of carpentry and home construction. Both honourable professions, but not so much what I'm curious about.

I realize that some may fit in multiple "yes" categories, e.g., both build gear they've designed as well as that designed by others. In that case, please choose the option that's the best fit or what you do the most of.

Thanks in advance.

Tom

How 'bout a classification for: "I have ideas for my existing audio gear (sound/function improvements) and I collaborate with someone who is a highly well know audio gear restoration specialist and have them do my special projects (several of which have been tested on this sight). I do not have the necessary time & board soldering experience to do it myself but I understand tolerances, etc. and discuss the feasibility of my projects with prospective people that may be able to do them (or can give me solid reasons not to do them)."

 

[fpitas]

I designed and built my own speakers, mainly because I wanted to learn how to design speakers. On the way, I developed a great respect for good speaker design engineers. I'll wire up patch panels with simple filters etc, but generally I just buy amplifiers, cables and other electronics. I get (more than) enough electronic design at work.

 

[mhardy6647]

me?
I have... issues.

 

[fpitas]

me?
I have... issues.

Cool beans. Are those 511s on top of the woofer cabinets?

 

[mhardy6647]

Cool beans. Are those 511s on top?

Nope.



EMILAR EH500-2.
It's kind of a long story. Suffice it to say that I started with 604E Duplex drivers in the cabinets, which I loved -- except for their HF dispersion (small "sweet spot").

 

[fpitas]

Nope.



EMILAR EH500-2.
It's kind of a long story. Suffice it to say that I started with 604E Duplex drivers in the cabinets, which I loved -- except for their HF dispersion (small "sweet spot").

TAD driver, maybe?

 

[mhardy6647]

TAD driver, maybe?

TAD: too rich for my blood.
They're JBL 2441 2" drivers.
I've also been known to use them with EMILAR throat adaptors and 1" Altec 802Ds, though.
I reckon this is a bit abstruse for the content and context of this thread.

 

[Gorgonzola]

I responded, "Yes - I build gear designed by others", because I have done that, and even designed my own speakers on a couple of occasions. But I certainly don't do either except very rarely. Further, I'm not sure whether construction kits consisting of built & tested modules really counts.

My most successful effort was to build Zaph Audio ZRT speakers which, IMO, are stupendous for what they cost mean in dollar terms. Further down the list is the amplifier, (crude but effective), I built an amp with a Class D Audio amp module and a Connexelectonic SPMS800RE power supply, (which power supply was recommended hear at as by our OP, @tomchr, and a sonic improvement, IMO, over the original CDA linear supply).

 

[fpitas]

TAD: too rich for my blood.
They're JBL 2441 2" drivers.
I've also been known to use them with EMILAR throat adaptors and 1" Altec 802Ds, though.
I reckon this is a bit abstruse for the content and context of this thread.

Perhaps. Although others are having fun showing off their stuff.