Jack 210

[gilmour]

[quote name='Spacehog' post='965934' date='Sep 23 2010, 06:30 PM']Nice build Gilmour, i'm now starting 2 112's.

what pu adhesive did you use?[/quote]

[url="http://www.screwfix.com/prods/44485/Sealants-Adhesives/Adhesives/Wood-Glues/Polyurethane-Adhesive/Joiners-Mate-Adhesive-500ml"]Joiners Mate[/url] from Screw Fix, you gotta watch which one you use there's two types, they're both fine, the clear needs water to cure properly.

[Spacehog]

[quote name='gilmour' post='966280' date='Sep 23 2010, 11:55 PM'][url="http://www.screwfix.com/prods/44485/Sealants-Adhesives/Adhesives/Wood-Glues/Polyurethane-Adhesive/Joiners-Mate-Adhesive-500ml"]Joiners Mate[/url] from Screw Fix, you gotta watch which one you use there's two types, they're both fine, the clear needs water to cure properly.[/quote]


Thanks

[Phil Starr]

[quote name='gilmour' post='965866' date='Sep 23 2010, 05:40 PM']My biggest concern is still the Piezo array and it's fragility, once it's all glued together an screwed to the wood it's certainly a lot stronger, but still feel like it needs some extra bracing somewhere - I even used solid copper to wire the piezos, definitely overkill for sound, but added a bit of strength.

I'm surprised but just how loud these are as PA cabs, for most gigs I'm doing they will actually be overkill, which I hadn't realised at the start, but two of these, running at 4ohms each, is a 1k rig! I don't need that for 80 people at a wedding lol. Anyway because of his they can cope with just about anything I throw at them, which is nice.[/quote]
I'm really interested in how you find these as PA speakers. What do you put through them? How are they on vocals? I've never managed to squeeze the sound I want out of piezos but they are working hard in my designs. The array means you are working each one much less but there are technical problems when high frequencies come from multiple sources spaced like these. The test of course is what they sound like and vocals are very revealing.

I guess I ought to check up on your gig diary next time I come up to Reading.

[LawrenceH]

[quote name='Phil Starr' post='969100' date='Sep 27 2010, 08:06 AM']I'm really interested in how you find these as PA speakers. What do you put through them? How are they on vocals? I've never managed to squeeze the sound I want out of piezos but they are working hard in my designs. The array means you are working each one much less but there are technical problems when high frequencies come from multiple sources spaced like these. The test of course is what they sound like and vocals are very revealing.

I guess I ought to check up on your gig diary next time I come up to Reading.[/quote]

Hi Phil,
I thought I'd chip in here as my father and I built a set of 4 Jack 110s using Deltalite IIs and the piezo arrays (2 with 12 piezso, 2 with 6, piezos imported from Speaker Hardware in the States). We initially tried them on bass without piezos and found the sound to be very good, smooth and with excellent clarity despite the lack of tweeters.
However.
On PA duties, the piezo arrays to my ears (and my dad's, a relatively experienced sound engineer) sound dreadful, and we spent a long time trying to EQ them and fiddling around with crossover frequencies. The Jack 10s were very boxy sounding overall, and the gap between the speaker cut-off and the piezos kicking in properly (from memory, somewhere like 1-2k is much more audible than the graphs led me to think it would be, and we found impossible to restore with EQ in a way that was satisfactory. I tried a bit of modelling in hornresp using the jack 10 design, and found it behaved pretty similarly to what was predicted, the cut-off is just too low for those piezos. Additionally, overall the mid/upper mid-range response sounded flat and lifeless yet somehow also harsh. Above 2-2.5k it's there, but it's not nice. And yes, although everyone on the BFM site insisted the wiring must be incorrect, we double and triple-checked and basically lots of tweeters together pretty much sounded to us like a phasey version of one on its own. I A/B'ed against an Eminence tweeter (NSD2005 I think? OEM in Yamaha PAs) coupled to a horn and that was significantly better especially lower down, although it's still far from perfect. Much greater clarity across the usable frequency range.

The Jack 10s are very loud though and as I said they did sound bizarrely nice on bass guitar. I actually think they'd work well as part of a 3-way design (although the lower-mid hump does make them very boxy so you'd really want to cross at about 800 max) but that sort of defeats the point of them. BFM insisted EQ was essential for any PA rig, I have to say I don't agree with that philosophy for little portable rigs but it is so for the Jacks as their untweaked response is very uneven indeed. But our experiences illustrated the point quite nicely that there's a lot more to speakers than flat frequency response. This works in the Jack's favour across some parts of the frequency range (I liked the upper-bass/low-mid clarity) but not others (anything 800-ish up).

My 2p, take or leave it! Others say they're very happy with theirs and good for them, this is just our experience although I will say we did try and exhaust possbilities of faults/errors on our part before making up our minds.

[Phil Starr]

[quote name='LawrenceH' post='969448' date='Sep 27 2010, 01:40 PM']Hi Phil,
I thought I'd chip in here as my father and I built a set of 4 Jack 110s using Deltalite IIs and the piezo arrays (2 with 12 piezso, 2 with 6, piezos imported from Speaker Hardware in the States). We initially tried them on bass without piezos and found the sound to be very good, smooth and with excellent clarity despite the lack of tweeters.
However.
On PA duties, the piezo arrays to my ears (and my dad's, a relatively experienced sound engineer) sound dreadful, and we spent a long time trying to EQ them and fiddling around with crossover frequencies. The Jack 10s were very boxy sounding overall, and the gap between the speaker cut-off and the piezos kicking in properly (from memory, somewhere like 1-2k is much more audible than the graphs led me to think it would be, and we found impossible to restore with EQ in a way that was satisfactory. I tried a bit of modelling in hornresp using the jack 10 design, and found it behaved pretty similarly to what was predicted, the cut-off is just too low for those piezos. Additionally, overall the mid/upper mid-range response sounded flat and lifeless yet somehow also harsh. Above 2-2.5k it's there, but it's not nice. And yes, although everyone on the BFM site insisted the wiring must be incorrect, we double and triple-checked and basically lots of tweeters together pretty much sounded to us like a phasey version of one on its own. I A/B'ed against an Eminence tweeter (NSD2005 I think? OEM in Yamaha PAs) coupled to a horn and that was significantly better especially lower down, although it's still far from perfect. Much greater clarity across the usable frequency range.

The Jack 10s are very loud though and as I said they did sound bizarrely nice on bass guitar. I actually think they'd work well as part of a 3-way design (although the lower-mid hump does make them very boxy so you'd really want to cross at about 800 max) but that sort of defeats the point of them. BFM insisted EQ was essential for any PA rig, I have to say I don't agree with that philosophy for little portable rigs but it is so for the Jacks as their untweaked response is very uneven indeed. But our experiences illustrated the point quite nicely that there's a lot more to speakers than flat frequency response. This works in the Jack's favour across some parts of the frequency range (I liked the upper-bass/low-mid clarity) but not others (anything 800-ish up).

My 2p, take or leave it! Others say they're very happy with theirs and good for them, this is just our experience although I will say we did try and exhaust possbilities of faults/errors on our part before making up our minds.[/quote]
wow, thanks a lot. The jacks are just an undersized conical horn with a reflex port, a nice design with some neat bits of improvisation but for me the phase plug needs to intrude into the cone area to avoid cancellation at high frequencies and the horn is a long way short of optimal. I'm open minded however I used to build my version of a horn/reflex hybrid years back for a number of bands and they always sounded sweet I was kind of expecting the sorts of things you are describing from the Jack though. That Yamaha is the horn I'm using for A/B 'ing with piezo's at the moment. The nearest I've got is with a 1" piezo driver with a big moulded horn which sounds pretty good but won't quite handle the power. Using multiple piezo's gives the phasing problems you describe. I'd love to use the piezo's because they are electrically more robust than the coil versions and I hate expensive crossovers. I know I'm going to end up with 'proper ' horns and an electronic crossover in my heart but I just want to try a couple more experiments first.

[LawrenceH]

[quote name='Phil Starr' post='969625' date='Sep 27 2010, 04:19 PM']wow, thanks a lot. The jacks are just an undersized conical horn with a reflex port, a nice design with some neat bits of improvisation but for me the phase plug needs to intrude into the cone area to avoid cancellation at high frequencies and the horn is a long way short of optimal. I'm open minded however I used to build my version of a horn/reflex hybrid years back for a number of bands and they always sounded sweet I was kind of expecting the sorts of things you are describing from the Jack though. That Yamaha is the horn I'm using for A/B 'ing with piezo's at the moment. The nearest I've got is with a 1" piezo driver with a big moulded horn which sounds pretty good but won't quite handle the power. Using multiple piezo's gives the phasing problems you describe. I'd love to use the piezo's because they are electrically more robust than the coil versions and I hate expensive crossovers. I know I'm going to end up with 'proper ' horns and an electronic crossover in my heart but I just want to try a couple more experiments first.[/quote]

I certainly wanted the piezos to sound good. But to me at least they really didn't and I consequently feel a bit sceptical about other people's glowing reports. Maybe some people just don't hear what I hear, or maybe there's some gross distortion using comp drivers that I'm strangely immune to (other than the usual harshness at the lower end of their useable frequency response). It wasn't a subtle difference though.

We fitted the not-really-a-true-phase-plug as recommended in the Jack plans and found the performance difference negligible. I'm interested to know if you'd think a more complex design would lead to a real-world noticeable improvement.

[gilmour]

I couldn't comment on the quality of the Piezos next to such experienced builders but they sound fine to me. I really liked the sound of the Omni 10 piezos and all, but as I've mentioned above the Jacks do require a lot more EQing. As a bass cab they work well, I'm still fine tuning them for PA.

Dave Perry did a good Comp Horn Vs Piezo comparison ages ago that was very informative, but I can't find the link. I'm sure He'll be along shortly...

[Phil Starr]

[quote name='LawrenceH' post='969678' date='Sep 27 2010, 04:59 PM']I certainly wanted the piezos to sound good. But to me at least they really didn't and I consequently feel a bit sceptical about other people's glowing reports. Maybe some people just don't hear what I hear, or maybe there's some gross distortion using comp drivers that I'm strangely immune to (other than the usual harshness at the lower end of their useable frequency response). It wasn't a subtle difference though.

We fitted the not-really-a-true-phase-plug as recommended in the Jack plans and found the performance difference negligible. I'm interested to know if you'd think a more complex design would lead to a real-world noticeable improvement.[/quote]
Hope Gilmour doesn't mind us taking over his thread like this, The problem the phase plug solves is that there are different path lengths in the cavity between the speaker and the mouth of the horn and you get destructive interference at the higher frequencies which limits the top end performance of the horn. in this case the mid range frequencies you describe as missing. Ideally I'd try to make a cross shaped piece extending back towards the cone but obviously clearing it and then extend the phase plate forwards to reduce cancellation across the mouth. If this bridged the gap between the 10" speakers and the horns then yes, it should make a real world difference. I haven't tried this though.

Just as an added point I've noticed that the quoted specs for these size of piezos vary from a bottom frequency of 2kHz to 4.5kHz so I guess they are not all the same.

[gilmour]

[quote name='Phil Starr' post='970186' date='Sep 27 2010, 11:06 PM']Hope Gilmour doesn't mind us taking over his thread like this...[/quote]

not at all, i feel my build diary is done, it's good to get others views and opinions

[LawrenceH]

[quote name='Phil Starr' post='970186' date='Sep 27 2010, 11:06 PM']Just as an added point I've noticed that the quoted specs for these size of piezos vary from a bottom frequency of 2kHz to 4.5kHz so I guess they are not all the same.[/quote]

I did wonder if the UK ones were different to the US ones in performance. I have the US ones, perhaps the UK units perform better. They're certainly more expensive.

Thanks for the plug description btw, I'd love to know if anyone's tried this, sounds a bit convoluted for us to do as an experiment when we're not happy with the HF anyway but in future may well try it.

Gilmour - thanks for letting us sidetrack the thread! Glad you're getting on with yours, would be very interested to hear them sometime and see how they stack up to ours.

Edited September 27, 2010 by LawrenceH

[Phil Starr]

Thought I'd do an update on my latest experiments with Piezo's. I've built a couple of 12+horns for PA and monitor use and my wife is away so I've been fiddling with them.

The speakers have Beyma SM212 12" drivers in a 45l box with cheapo piezo compression drivers with a simple attenuator so the piezo's won't conk out when I put 300W through them.

I've A/B blind tested them (well I didn't tell my daughter/test subject which speaker was which) with the Yamaha S112V's that I usually use as PA. Young people and women have better hearing and I didn't want wishful thinking to colour my judgement so thanks Naomi for being my guinea pig. I was expecting the bass to be better as the Beyma's far outspec the Eminence Deltas the Yamahas use but didn't think the piezo's would be anywhere near the 2" compression drivers and proper crossover in the S112's, especially since when I tried them when I first built them there was a real hole in the midrange. Wrong!

Piano, female vocals (Grace Slick, Joan Armatrading, I'm a bit old fashioned) male vocals all jumped out of the mix with much better detail and the midrange suckout had all but disappeared The bass tone was fantastic, but I knew that anyway since I often use them as part of my bass stack. I think what has happened is that using the Beymas has broken them in allowing the cones to flex more and increasing the midrange so there is no longer a gap. I wish I'd measured them when they weren't sounding so good so I could have a before and after plot.

So, my conclusions are: piezo's can sound OK even in midpriced/mid-performance speakers and speakers really do 'break in' over time. If anyone is interested I'll start a new thread and put up a few details

Edited October 25, 2010 by Phil Starr

[LawrenceH]

[quote name='Phil Starr' post='1000645' date='Oct 25 2010, 11:26 PM']So, my conclusions are: piezo's can sound OK even in midpriced/mid-performance speakers and speakers really do 'break in' over time. If anyone is interested I'll start a new thread and put up a few details[/quote]

Definitely interested in that - what piezos, how many, crossover and frequency if used. Id love to know how to make piezos sound less than awful!