DQ828 Posted June 14, 2015 Posted June 14, 2015 I normally spray the Duratex on & then spray colour over the top, I'm after a finer texture for the things I do with it, it's great stuff & sets like a rock after about a week. It's a water based paint that can be sprayed or rolled on, I buy the roller version & water it down for spraying, I end up getting about 15% more that way, rather than buying the spray version.
zog Posted June 14, 2015 Posted June 14, 2015 A small Class D amp build, with a little bit more effort that I usually do with the enclosure: This is a "Wiener" TPA3118 Class D amp board with a 50K stepped attenuator. Powered with a 50W 20VDC SMPS (laptop brick type, but fairly good quality one). The "Wiener" boards were made as a high quality (as in reasonable Mouser sourced parts rather than no-name Chinese) version of the TPA3116 boards with dip switches for DIY types to play with the options available on these ICs, e.g. modulation frequency, etc. more info: http://www.diyaudio.com/forums/group-buys/269855-wiener-tpa3118-amplifier-card.html 4
Guest Posted June 14, 2015 Posted June 14, 2015 What's the other wooden box on the left in the first pic? Also someting home made?
mwhouston Posted June 14, 2015 Posted June 14, 2015 It looks like a low power amp module. I have found even the 100W modules when pushed distort early. Also all my Ds so far have linear PSs. I think it's the secret to getting the best from Ds.
davewantsmoore Posted June 15, 2015 Posted June 15, 2015 (edited) Upper-bass horns. Slow progress...... Still unsure whether these will be the final prototype or not ..... slapped a bit of varnish on them over the weekend before the damp winter weather gets into them too much.... and they look better than expected (I had low expectations). They still need their lids on .... but first some final tweaking with the internal lining / bracing (more) .... and a brace on the rear chamber cover which will press against the driver magnet. Then I'll drag them over to the park next door for some measurements .... and then get to in-room tweaking. I suspect they will need some vertical braces near the horn mouth .... although I'll be using a thick rubber matt on top, in between them and the midrange horn. The plan for the mid horn eventually is to hang it from the ceiling, or make a suspension arm from the side wall for it (so it doesn't touch these upper bass horns at all). We'll see. I had a lid clamped on to one briefly yesterday, and just a quick crossover filter (no other EQ) ..... and the initial impression was a "velvet sledgehammer". The texture and detail in a bass guitar or low brass was just beautiful .... but the attack of something like an action movie or percussion could nearly take your head off.... and then stop on a dime. Details: Acoustic Elegance 15" (TD15M) driver in 1.7m long horn. Horn is an (approximate) hyperbolic exponential expansion T=0.8, with a fairly low compression ratio 1.75 to 1) Bandwidth = +/- 1dB from 60 to 300Hz Sensitivity = 112dB @ 1m from 2.83v in a room corner Impedance = 10 ohm, +/- 2 ohm Target frequency response = -6dB @ 50hz and 280hz... with 48dB per octave slopes. Excursion (cone movement) = 0.25mm for rated output (!!!) Edited June 15, 2015 by davewantsmoore 9
zog Posted June 15, 2015 Posted June 15, 2015 What's the other wooden box on the left in the first pic? Also someting home made? No, just an LED digital clock, one of those fake woodgrain plastic ones. It looks like a low power amp module. I have found even the 100W modules when pushed distort early. Also all my Ds so far have linear PSs. I think it's the secret to getting the best from Ds. Yes, these type of chips are on Ebay with all sorts of fanciful wattage claims that shows they were probably using it as a fuzzbox when they made the measurements, but I'd say its a 30W amp at full voltage (24VDC) , and I'm running at 20V so maybe 20W/ch is closer to the mark. from: http://www.ti.com/product/TPA3118D2/datasheet/specifications#SLOS708544 This is being used in a bedroom with 94db sensitive speakers (12" woofers, waveguides) at low-moderate volume so more than enough power.. I've also happily used my 8W class A, 15W chipamp, etc in there. My two "best" class D amps do have linear power supplies so perhaps an outboard 24VDC PSU is a future enhancement for this one, I could stick it in another matching pine box. 1
hochopeper Posted June 15, 2015 Posted June 15, 2015 Then I'll drag them over to the park next door for some measurements .... and then get to in-room tweaking. I suspect they will need some vertical braces near the horn mouth .... although I'll be using a thick rubber matt on top, in between them and the midrange horn. The plan for the mid horn eventually is to hang it from the ceiling, or make a suspension arm from the side wall for it (so it doesn't touch these upper bass horns at all). We'll see. Seems ... elaborate. How heavy is mid-bass horn? Where does PSE144 fit in this ? I had a lid clamped on to one briefly yesterday, and just a quick crossover filter (no other EQ) ..... and the initial impression was a "velvet sledgehammer". The texture and detail in a bass guitar or low brass was just beautiful .... but the attack of something like an action movie or percussion could nearly take your head off.... and then stop on a dime. Was this inside a room? (and was it A/B switched )
davewantsmoore Posted June 15, 2015 Posted June 15, 2015 I have had this idea floating around in my head of this pair of floorstanders. That would work quite well.
davewantsmoore Posted June 15, 2015 Posted June 15, 2015 Seems ... elaborate. How heavy is mid-bass horn? Where does PSE144 fit in this ? Sorry... by "mid horn" I mean the PSE144. For now, the mid-horn (the PSE144) will sit on these upper bass horns ..... if that's a (vibration) problem which can't be cured, then I'll suspend them on some type of arm or platform, or hang them up (?! maybe) Was this inside a room? (and was it A/B switched ) It was both in my driveway, and in the listening room.... and yes, it was A v B v A+B switched between my rear speakers - although nothing was positioned particularly well (the room is being renovated right now). The space "inbetween the notes" was what was really nice. I played a stem of my mate on drums.... very very snappy. This design is the highest efficiency woofer solution I've ever had the opportunity to tinker with. I need to find some charts which can demonstrate this.... but I will need to dial the measurement setup in further first before I bother taking a bunch of measurements of different speakers (it's more work than it sounds). 1
davewantsmoore Posted June 15, 2015 Posted June 15, 2015 PS - I used the amplifier you built me to test them 1
Equaliser Posted June 20, 2015 Posted June 20, 2015 http://www.stereo.net.au/forums/index.php?/topic/84580-stax-sra-3s/ Working on the Unison Research SR-1 amp now. Follow full details in the lids and schematics threads. 1
mwhouston Posted June 27, 2015 Posted June 27, 2015 Moving ahead with the tube preamp build. The Kit section was completed a few weeks back and now the rectifier and smoothing cct. brd. is complete. Gaps on the brd are for external 5H choke and onboard limiting resistors. Filtering on the HT is; C-L-C-R-C. The filament section has a 12V regular. Also the 1U enclosure has been mostly drilled and RCAs and power cords etc mounted. More drilling ahead but this project is starting to take shape. 3
Guest Posted June 28, 2015 Posted June 28, 2015 No, just an LED digital clock, one of those fake woodgrain plastic ones. :lol: Fair enuff
TMM Posted June 30, 2015 Posted June 30, 2015 Experimenting with a small waveguide for a 2" dome midrange (Jaycar CM-2092/Dayton DC50F-8). Started making a positive MDF mold, needs bodyfiller then I can make a fibreglass negative mold from it and then the finished fibreglass waveguide. It's going into this (probably not what you were expecting!): I've had these for pretty much forever so they have some sentimental value. Jaycar 8" poly woofer and some cheap Jaycar 1" silk tweeter. Originally it was built as a 2-way which I remember being awful and having to EQ the breakup node of the woofer down like 10dB! Then at some point they were converted to 3-way with Jaycar 5" sealed back cone midranges and prebuilt 3-way crossovers. With a couple of L-pads that miraculously worked out to be somewhat tonally flat. Picked up the 2" domes NOS off ebay recently. The baffle layout is not the best but i can't be arsed to change it now. I swapped the positions of the tweeter and port because the edge diffraction on the tweeter is awful in the corner.
blakey72 Posted July 1, 2015 Posted July 1, 2015 Not a big project but just ordered some RG213/U cable and banana plugs to make up some bi-wire speaker cables. Need something to play with
Owen Y Posted July 1, 2015 Posted July 1, 2015 Good concept. It may be a bit late, but maybe you could roll the outer edge too - again to minimise baffle step-edge irregularities. Cheers, Owen Dark Lantern blog - http://darklanternforowen.wordpress.com/ Experimenting with a small waveguide for a 2" dome midrange (Jaycar CM-2092/Dayton DC50F-8). Started making a positive MDF mold, needs bodyfiller then I can make a fibreglass negative mold from it and then the finished fibreglass waveguide.
TMM Posted July 1, 2015 Posted July 1, 2015 (edited) Good concept. It may be a bit late, but maybe you could roll the outer edge too - again to minimise baffle step-edge irregularities. Cheers, Owen Dark Lantern blog - http://darklanternforowen.wordpress.com/ I'm going to flush mount the waveguide in the baffle, driver will be mounted from the rear, that's why i made it exactly the same diameter as the driver's faceplate. Ideally it should be a bit bigger but hopefully it gives me the gain I want from ~1-4KHz to get the non linear distortion down (this drivers achilles heel). If it turns out to be an acoustical failure I can just use the driver without a waveguide . Edited July 1, 2015 by TMM
Guest Posted July 1, 2015 Posted July 1, 2015 Converting this into (hopefully) this I can't see the pics
awty Posted July 1, 2015 Posted July 1, 2015 Neat project betocool. I reboxed some old celestion speakers once, made a huge improvement, better once I recapped the cross overs and did a better job of bracing. Are you using the same internal volume?
Guest Posted July 1, 2015 Posted July 1, 2015 Gaaaaah, what is it? Tried cutting the link from beto's post and pasting it in to browser and it tells me I need to sign in to Google
betocool Posted July 1, 2015 Posted July 1, 2015 Neat project betocool. I reboxed some old celestion speakers once, made a huge improvement, better once I recapped the cross overs and did a better job of bracing. Are you using the same internal volume? Yes, pretty much the same with some error here or there. I might change the caps in the future, but it really is only a low budget project to keep me busy and entertained. The reasoning was, I liked the sound of them (verge rubbish treasure) but I don't like the looks at all! Gaaaaah, what is it? Tried cutting the link from beto's post and pasting it in to browser and it tells me I need to sign in to Google I'm enjoying this! Ha ha ha! Very funny! However, I will put you out of your misery and repost the pictures:
Guest Posted July 2, 2015 Posted July 2, 2015 Nice boxes for sure. Those speakers remind me of some I have somewhere.... New boxes should make a difference. Also.... I see your marked workbench and raise you a few cuts and nicks :lol:
mwhouston Posted July 2, 2015 Posted July 2, 2015 Nice boxes for sure. Those speakers remind me of some I have somewhere.... New boxes should make a difference. Also.... I see your marked workbench and raise you a few cuts and nicks :lol: image.jpg image.jpg image.jpg Cleverly framed and with the right lighting, you have an interesting photo here.
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