Auracle Posted August 14, 2017 Share Posted August 14, 2017 Looks like I've made a rod for my own back. Running an educational GTG as compared to a show-and-tell (and drink) format. Does anyone in SNA land know if a gtg has been run along similar lines, or will this be the first? If anyone has a suggestion for formats, let us know. Does SNA also get a portion of my apples? Link to comment Share on other sites More sharing options...
Upfront Posted August 14, 2017 Share Posted August 14, 2017 Looks like I've made a rod for my own back. Running an educational GTG as compared to a show-and-tell (and drink) format. Does anyone in SNA land know if a gtg has been run along similar lines, or will this be the first? If anyone has a suggestion for formats, let us know. Does SNA also get a portion of my apples? I haven't seen one. Lots of informal educational talk but not what your suggesting. Link to comment Share on other sites More sharing options...
Rob181 Posted August 14, 2017 Share Posted August 14, 2017 4 hours ago, Auracle said: Does SNA also get a portion of my apples? What variety are the apples... Link to comment Share on other sites More sharing options...
Upfront Posted August 14, 2017 Share Posted August 14, 2017 What variety are the apples... More importantly, can they be made in to cider before the GTG! 1 Link to comment Share on other sites More sharing options...
shaky Posted August 14, 2017 Share Posted August 14, 2017 Cider? Did someone say cider? 1 Link to comment Share on other sites More sharing options...
Auracle Posted August 15, 2017 Share Posted August 15, 2017 Maybe I should start another thread on "how to make alcohol whilst listening to background music class". -this is Brian's thread afterall, and we really should get back on topic. Link to comment Share on other sites More sharing options...
Upfront Posted August 15, 2017 Share Posted August 15, 2017 Maybe I should start another thread on "how to make alcohol whilst listening to background music class". -this is Brian's thread afterall, and we really should get back on topic. [emoji13] Link to comment Share on other sites More sharing options...
Rob181 Posted August 15, 2017 Share Posted August 15, 2017 7 hours ago, Auracle said: Maybe I should start another thread on "how to make alcohol whilst listening to background music class". Really looking forward top this one...give me a yell when you do start it... 1 Link to comment Share on other sites More sharing options...
BioBrian Posted August 15, 2017 Author Share Posted August 15, 2017 1 hour ago, Rob181 said: Really looking forward top this one...give me a yell when you do start it... May I respectfully suggest you start it yourself, and leave this thread to those who don't need to be yelled at. A closer reading might reveal that Sam, who has been in consultation with me over this build, has more serious intentions in life, as do I. Link to comment Share on other sites More sharing options...
Rob181 Posted August 15, 2017 Share Posted August 15, 2017 4 minutes ago, BioBrian said: May I respectfully suggest you start it yourself, and leave this thread to those who don't need to be yelled at. A closer reading might reveal that Sam, who has been in consultation with me over this build, has more serious intentions in life, as do I. May I respectfully suggest you look at who made the comment to which I referred... That you have chosen to be a SP over a "throw away" line posted by @Auracle... And my response to that line is your problem...no one else's... I highly recommend you Google "sense of humour"... Link to comment Share on other sites More sharing options...
BioBrian Posted August 15, 2017 Author Share Posted August 15, 2017 You totally missed the thrust of Auracle's line. React if it pleases you. I have a very busy sense of humour, but you might want to observe, as I've had to, that when a joke gets no response, it can be assumed that it was not at all appreciated. I'm actually more concerned with future readers who, like me, might get very sick of the crap that invades threads and drains the good energy and direction that they can generate. Link to comment Share on other sites More sharing options...
Upfront Posted August 16, 2017 Share Posted August 16, 2017 So what's the next step Brian? Are you still contemplating which drivers you will use? Link to comment Share on other sites More sharing options...
BioBrian Posted August 17, 2017 Author Share Posted August 17, 2017 Well another little package came from Nigel yesterday: 3.9 mH C-coils, which are to try as ' first entry' to the 3-Way crossovers. That means dropping the DCR to the woofer, which I'm hoping might even up the balance again. The previous inductor was 3.9 mH, with 0.66 Ohm DCR; these drop to 0.08 Ohm. I'll try to get them in today and have another go with just one amp running the lot - it would be great to keep it that simple. For the last couple of days, I've had your Pre 1 and Parasound running the big woofers, and Cyrus on top, which I could balance, power-wise, and gave the clearest sound I've had yet. (Quite pleasing, really). I still have odd tweeters, and have been playing with the balance between them - for some reason the Scanspeak one sounds more out-of-the-way and more dynamic than the SB Acoustics, but this still may be due to attenuation levels. With attenuation, I've found the gap between 4.7 and 6.8 Ohms too big, so have had to calculate resistor pairs, using the formula R1 x R2 over R1 + R2. I tried 10 + 18 = 6.43 Ohms, but will go to 12 + 15 = 6.67 for the SBA tweeter.today. The SSpk one's pretty right on 3R. I had a mail from Per Skaaning last night with more info on the lusted-after drivers. Plan had been to use the (23 cm diameter - 8") 23 I 52 in the 30 litre sealed box, but he said it needs vented, as its EBP is about 140. EBP is Fs over Qes, and I don't come across this as an important design consideration very often. Troels seems to ignore it when doing his 100-200 Hz sealed boxes for tight punchy upper-bass/lower-mid. I'm hoping the EBP thing is only important in getting efficient bass out of a driver, which I don't need, but would like to hear from any readers here, who may throw some light on it. Link to comment Share on other sites More sharing options...
lusk Posted August 17, 2017 Share Posted August 17, 2017 HI Brian, Been trying to follow where your at the moment, 15" bass driver active + 3way troels (8" SB acoustics?? or Jantzen??) is this correct? So the new inductor 3.9mH with lower DCR is for the 8" to get slightly more output? Re:AT drivers Will you be using the sealed box to act as the high pass (like Troels design) or using a crossover filter? The driver will be different for each, EBP will need to drop so driver pushes lower in sealed box so then you add your crossover filter. Link to comment Share on other sites More sharing options...
BioBrian Posted August 17, 2017 Author Share Posted August 17, 2017 (edited) On 17/08/2017 at 12:32 PM, lusk said: HI Brian, Been trying to follow where your at the moment, 15" bass driver active + 3way troels (8" SB acoustics?? or Jantzen??) is this correct? So the new inductor 3.9mH with lower DCR is for the 8" to get slightly more output? Re:AT drivers Will you be using the sealed box to act as the high pass (like Troels design) or using a crossover filter? The driver will be different for each, EBP will need to drop so driver pushes lower in sealed box so then you add your crossover filter. Hi Lusk, and anybody with else with the patience, it's been a long day in the chariot for a recently-dissected specimen (I meant me, but the speakers too). Quite a few changes, quite a few loose ends sorted: The new 3.9 mH C-coils went in, as inductors for the 8" woofer. These have done the job of raising the sensitivity of the upper 3-ways, better matching the bottom 15" woofers. I put the Scanspeak tweeter back in its little L-frame to return for duty as part of my Centre speaker, in the 7.1 system at the house. Fitted the other SB tweeter back in the 3-ways, so they're now symmetrical again. Put the 12 + 15 R = 6.67 R resistor parallel pairs in, as tweeter attenuation. This worked: it sounds more like a proper working system with the symmetry. May need to go back to 6R8 if it stays this bright, but will wait till it's played in a bit more. Fitted new 39 uF Cross Caps to the bottom 4th Order passive LP filter. It had been a bit of a bird's nest with paralleled caps, so is now one level neater. The upper 3-way is still based on Troels' SB 3-way crossover. This remains all 2nd Order, with no HP woofer filter, other than acoustic roll-off by the sealed 40 litre box. Main changes to the design are: - SBA TW29RN tweeter, instead of cheaper SB29RDC-C000-4. - SBA SATORI MW13P-8 mid, instead of smaller SB12MNRX25-4. - Troels Gravesen/SEAS JA8008 woofer (94 dB, as opposed to 88.5 for the original SBA SB23NRXS45-8). - 8" Woofer C-coil has much lower DCR, and nearly double the mH, due to using the JA8008 driver. Also to cut its mid-range output to suit XO to mid. - Mid gets 50% more uF in HP section to lower crossover point to woofer. Also a CR across its LP coil, to tame upper roll-off and XO point. - Attenuation adjustments, and placement of resistors within filters. - And of course addition of the bottom SBA SB42FHC75-6 15" woofer below, in its 240 litre vented box. It has 4th Order passive filter. Today I re-wired the whole caboodle to run as a 4-way passive again, all off Linc's Bel Canto Pre 1 and the Parasound A 21 power amp. (I think the A 21 enjoys having something to do for a change). Sorry, pictures might be a better way of presenting all that, but I'm not skilled in doing hybrid photos with text added. The upshot of all that is a pretty nice speaker system. I ran a few of the usual CDs through - Prokofiev, Stravinsky and Mahler, but look forward to getting the Server plugged in to deliver some Hi-Def files. Just in case there was a good drum track, I played some bits from Abbey Road, but it didn't have what I expected. But quite a shock - I've never heard such separation, such clarity, such a raw '60s sound, and all the lyrics so clear. Just goes to show how attitudes, presumptions, and memory, change over 2 years - I really need to go back to previous speakers to get this in contrast. I've created something pretty different, and I'm getting to accept that it's a big step up from what I've had in the past. The voicing sort of works, with, as I mentioned above, maybe a bit too much brightness from the tweeters. The prototype tweeter 'wings' are still on, which does brighten the treble. What bothers me is a kind of 'cuppy' sound from the mids. I had this complaint with the original 4" mids, but maybe this EBP thing, mentioned in my previous post, might just have the clue. Both drivers are sealed in accordance with WinISD - correct volume for Qtc of 0.707, but both sound wrong to me. I've checked their EBP numbers, and guess what? - they're both about 140, which is what Per said needs vented enclosures! The new AT 8" would be expected to have as little bass as possible, so I can keep the sealed (it would reduce to about 30 litres) box and not have to make an expensive HP filter for it. Another puzzle is that the 15 H 52 06 13 SDKA mids that I'm talking about with Per have an EBP of 130, and he says 4-5 litres sealed would suit them. I have a note here saying "Glasswolf Pages", so I probably need to look that up again and try to work out something. For this mid, Troels uses an aperiodic vent in 4.9 litres, so I can build that in, with some difficulty (vent might have to be out one side). Fitting a vent and doubling the inner box size for the present mids would be a major rebuild. So I'll keep considering the AT drivers, which would need a rebuild, but would be (more?) permanent. Yeah, that sounds good. Give me more of this transparency thing I keep hearing about, please Universe? So @lusk, please spell it out for me simply, if you can advise on EBP - and anything else that comes to mind of course. As usual, I welcome comments or advice from all readers. If you're shy, please PM. It could save a lot of dollars! Edited October 12, 2020 by BioBrian driver correction Link to comment Share on other sites More sharing options...
lusk Posted August 17, 2017 Share Posted August 17, 2017 11 hours ago, BioBrian said: What bothers me is a kind of 'cuppy' sound from the mids. I had this complaint with the original 4" mids, but maybe this EBP thing, mentioned in my previous post, might just have the clue. Both drivers are sealed in accordance with WinISD - correct volume for Qtc of 0.707, but both sound wrong to me. I've checked their EBP numbers, and guess what? - they're both about 140, which is what Per said needs vented enclosures! EBP is a guide to show weather a driver is suited to sealed or ported when considering the drivers low end frequency response. Efficiency Bandwidth Product, eg. value of 50 = more bandwidth less efficiency, 140 = less bandwidth more efficiency Using a midrange driver with EBP of 140 in a sealed enclosure doesn't matter because you may not require the driver to go low but you want reasonable efficiency. Its difficult to offer suggestions on your issue with mids without seeing measurements of each driver and total response. Link to comment Share on other sites More sharing options...
BioBrian Posted August 17, 2017 Author Share Posted August 17, 2017 Thanks, lusk. I need to learn more about Qes. Relieved - it sounds like sealed will suit what I want from both new drivers. Using the box to control/suppress bass, but not damping dynamics too much. I'll try to do a set of measurements as you suggest - the cupiness may well be due to the JA8008 going too high into the mid's territory. I haven't spent much time on it, as I'm pretty desperate for them to go back to their proper homes. But I think listening to the mids on their own shows the same uncomfortable sound. I thought it might be because either the 2.6 litres is too small, or there's a reflection off the flat back wall of the mid box. I do have a hard foam shape there to dissipate it, but it did seem a bit crazy to put this Satori driver in a box it only just fits in. Link to comment Share on other sites More sharing options...
BioBrian Posted September 2, 2017 Author Share Posted September 2, 2017 Another couple of improvements today - sounding best yet. The 2.7 mH C-coil inductors arrived from Jantzen (via Speaker Bug), so they went into the bottom woofers' 4th Order LP filters. These C-coils are 12 and 14 AWG, meaning 2 mm and 1.63 mm diameter copper wire - nothing else directly in the signal path, and only 0.12 Ohms DCR for both of them. Bass music through the woofers took on another level of clarity and space. Also 2 new supercaps: I'd been using 2 Jantzen Superior-Z 15 uF capacitors in the mid-section HP filter, supplemented by 1 'ordinary' 15 uF Standard-Z. This had gone to some forgotten vault in my mind, as I'd thought "well it's probably nearly as good as 3 Sup-Zs", but I was wrong. 3 Sup-Zs immediately sounded quite different from the mid-driver. A kind of haze was lifted, the sound is silky smooth, and the image is more focussed. Oddly, that cuppy-ness from the mids that I described in the last post seems to have gone. I let them play for a few hours, then came back to listen again. The outrageous athletic tympani and bass-drumming, near the end of Stravinsky's Rite of Spring (Minnesota Orchestra HDCD) had a new freedom and overtness, and there was no sense of phase or timing problem between upper and lower woofers. It's so nice when something goes right. 1 Link to comment Share on other sites More sharing options...
Upfront Posted September 2, 2017 Share Posted September 2, 2017 Good to hear you've had some luck mate! Well done! Link to comment Share on other sites More sharing options...
BioBrian Posted September 2, 2017 Author Share Posted September 2, 2017 Thanks Linc - your lovely Pre might have something to do with it! Link to comment Share on other sites More sharing options...
Upfront Posted September 2, 2017 Share Posted September 2, 2017 Recon your speakers have more to do with it mate. Beautiful things Link to comment Share on other sites More sharing options...
BioBrian Posted September 10, 2017 Author Share Posted September 10, 2017 (edited) Still stewing over the extravagance of ordering AT drivers and crossover kit. It's all falling into place though, so pressing the button is close. Aesthetically, the upper 3-ways "Beops" are too small for the giant lower woofers "Bel Giza". At their base, they are 6 cm narrower than the big woofers. They sound great up close, but there's something not right in the imaging, when you have such a large vertical structure bringing music at only 2.6 m distance: the triangle (in orchestral music) always comes from upper left (half-way up the wall in a concert hall), and the basses are lying on the ground when playing low notes, and stand up again when in higher ranges. I need to sit further away, which means more air needs to be moved, and the image should sharpen and present more naturally (if the room's OK of course). The 3-ways need a sensitive woofer, more area for the tweeter, and, I think, a mid-range driver that can move more air, more easily. This is a large speaker system that would suit a large room, so I think the AT (155 mm diameter) 15H52 is going to just do a whole lot more than the 132 mm Satori one here at present. Present and Projected: There's another thing. The crossover between the AT 23I52 (8") and 15H52 (5") would be around 300 Hz, and with the above projected baffle, this neatly corresponds to the baffle step F3 of around 300 Hz with this wider baffle. The sensitivities of the 2 drivers are 94 and 89, which looks awfully close to equalizing the baffle step, which would happen around crossover frequency. As can be seen from the above photo, the wings that proved to measure best with 2 different tweeters are still visible out the sides, but the top extension has been incorporated in the box dimensions. I could make a separate box for the tweeter, which would also allow alteration of the baffle size, angle, and "Z-offset", or fore-and-aft adjustment. Edited September 10, 2017 by BioBrian typo 2 Link to comment Share on other sites More sharing options...
davewantsmoore Posted September 20, 2017 Share Posted September 20, 2017 (edited) On 17/08/2017 at 7:16 PM, BioBrian said: What bothers me is a kind of 'cuppy' sound from the mids. I had this complaint with the original 4" mids, but maybe this EBP thing, mentioned in my previous post, might just have the clue. Both drivers are sealed in accordance with WinISD - correct volume for Qtc of 0.707, but both sound wrong to me. I've checked their EBP numbers, and guess what? - they're both about 140, which is what Per said needs vented enclosures! The frequency response of the driver is what you hear. If you have nothing else but the box / vent to control the response.... then that is what will dictate. If you have other things, like crossover filters, or other EQ - you can tailor the response to whatever you want. So, is the "EBP the cause of the cuppy sound" ..... Yes, if you let it be. Does this mean that a certain EB driver, in a certain box with have a certain sound ..... No - that's a misnomer. It's the specific frequency response curve, which has the specifc sound. Edited September 20, 2017 by davewantsmoore 1 Link to comment Share on other sites More sharing options...
BioBrian Posted September 20, 2017 Author Share Posted September 20, 2017 (edited) Just to prove that not all this is 'over the top', I finally finished the chassis/trolley things, so I can move these 130 kg monsters around. It took a hefty ceiling bracket, a half-tonne chain block and a bit of nervous energy to bolt the chassis things underneath, but the lever-thing with castors worked better than I'd hoped. It's easy to lift the fronts, and the rears are on fixed wheels, so with a fair wind, they can be put (sort of!) out of the way, or in different positions for listening. Of course, the sharp-eyed will notice the audiophile-standard fly-wire mesh fitted to the vents, to keep out rodents and the dreaded mud-wasps! Unfortunately, and this may be too subjective, on 1st listening, they sounded a bit vague, the image deteriorated a little. I think there may have been a benefit from them sitting on their bolts, directly on the concrete. Never mind for now*. * Rubbish! See next post. Edited September 24, 2017 by BioBrian 2 Link to comment Share on other sites More sharing options...
Upfront Posted September 20, 2017 Share Posted September 20, 2017 A very clever idea mate. Hopefully it will save whats left of your back! Link to comment Share on other sites More sharing options...
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