"The Minimus" Project

2

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  • VR3
    VR3 Posts: 27,965
    If you could get me perfect nhung measurements, I can cut that all day 😁
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • F1nut
    F1nut Posts: 49,708
    skrol wrote: »
    I have a friend who used to work for Polk Audio back in the later 80's early 90's (ZSP) and worked on the Monitor Series 2, RTA (TL) SDA (TL) and S series. When I asked him about tweaks for my RTA11TL's he mentioned that they played around with putting felt around the tweeters but didn't get much benefit. Perhaps this material is better suited? It certainly looks more absorptive than regular felt.

    I'm not surprised as the raised bezel on the SLxxxx/RDOxxx tweeters already addresses the diffraction issue. Years ago in an attempt to tame the SL2000 I tried purpose made diffraction pads. They didn't do a damn thing because the real problem lay elsewhere.
    Political Correctness'.........defined

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  • gp4jesus
    gp4jesus Posts: 1,969
    VR3 wrote: »
    If you could get me perfect nhung measurements, I can cut that all day 😁
    you’ve proven again you are bigger and better😊.

    At the moment I’m taking advantage of the gorgeous N GA spring weather doing battery maintenance on my small fleet of cars, vans, and SUVs.

    Taking a close look @ the tweets...

    they’re exactly 1” in diameter, very slightly horn loaded though I’m sure all will agree that tweeter demands we cover those shiny surfaces!

    From your pics I see you can get very precise. I suppose just tiny fraction larger than an inch should do it allowing the felt to appear to horn load the tweeter. In the interest of simplicity I may go basically square*/rectangular** from the baffle top to the mid top*/side edges**.
    *A7s **A6

    Taking a close look @ those mids...

    Before I start measuring, should I allow the silver trim ring* exposed? It* does horn load the driver just slightly. Mostly it makes them look pretty.


    Perhaps I could attempt a template for the center. Either way advise me on the A6 tweeter/port arrangement.

    Both speakers front baffles are, I think, 8 3/4” across (A7) or high (A6). I’ll get back to ya w/the details.

    Please PM an e$timate to me. One day I may do the same for my ‘A3 surrounds.

    1000 thanks in advance for even considering doing this. Perhaps a simple tweak for the so many other speakers using that tweeter
    Samsung 60" UN60ES6100 LED Outlaw Audio 976 Pre/Pro Samsung BDP, Amazon Firestick, Phillips CD Changer Canare 14 ga - LCR tweeters inside*; Ctr Ch outside BJC 10 ga - LCR mids, inside* & out 8 ga Powerline: LR woofers, inside* & out *soldered LR: Tri-amped RTi A7 w/Rotels. Woofers - 980BX; Tweets & “Plugged*” Mids - 981, connected w/MP Premiere ICs Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”. Power Conditioning & Distribution: 4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s *Xschop's handy work
  • VR3
    VR3 Posts: 27,965
    Made a custom mount for a barrier strip (with a little modification) to go external. Will combine the ground to one output

    h5hrnaprmlox.jpg
    deyilfpoghva.jpg
    huf2jnlmy7y5.jpg
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • VR3
    VR3 Posts: 27,965
    edited March 2021
    Dh labs t14 internal wiring, direct soldered
    Filled enclosure with polyfill
    ygoaanhf8hjs.jpg
    0j3mg8qok43q.jpeg
    ge2uu2ucxjzc.jpg
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • VR3
    VR3 Posts: 27,965
    All mods up to this point, with diffraction pads, at the listening position
    pv0rbyie5w6r.png

    No diffraction pads
    eid42fe8zzd9.png

    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • BlueFox
    BlueFox Posts: 15,251
    So it is basically indistinguishable between the two?
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    Three 20 amp circuits.
  • VR3
    VR3 Posts: 27,965
    edited March 2021
    I wouldnt say there isnt a difference, with the pads on it is almost ruler flat from 300hz to 1.5khz versus some peaks and valleys and a reduction in peaks in other parts of the graph

    This is a desk setup so nearfield
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • VR3
    VR3 Posts: 27,965
    edited March 2021
    For comparison sake, this is the Definitive PowerMonitor500 at the same listening position (PM 500 has an 8" powered sub per speaker, 4.5" midrange, 1" tweeter.

    7kv8xcy1a6g6.jpg


    No where near as flat, but also not saying the Minimus 7 sounds better or worse. No comment on that yet haha

    8qzy556kqcnh.png
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • mhardy6647
    mhardy6647 Posts: 32,926
    edited March 2021
    VR3 wrote: »
    I wouldnt say there isnt a difference, with the pads on it is almost ruler flat from 300hz to 1.5khz versus some peaks and valleys and a reduction in peaks in other parts of the graph

    This is a desk setup so nearfield

    I'd expect the smoothing out of that hump from 2 to 4k would be both audible and quite beneficial :)

    Also, it would ;) be interesting to look at the frequency-dependent dispersion pattern sans and avec the baffle matting. That would probably show substantial alteration (I would think) -- again, with significant audible consequences in terms of "transparency" of the sound. I always found the Minimus-7 (and most R/S loudspeakers of the 1970s into 80s) to be quite opaque sounding -- as in "not transparent". The source of the sound, from most of them, was often blatantly obvious; the speakers call attention to themselves "as is".

    The mod, apparently, improves that substantially, based on early posts to this thread.

  • xschop
    xschop Posts: 4,636
    Looks like an improvement for sure. What is the x-over point?

    Don't take experimental gene therapies from known eugenicists.
  • VR3
    VR3 Posts: 27,965
    That frequency response at the listening position is crazy because that's still the stock "crossover". As I am waiting on parts.

    The woofer is full range and the tweeter is a simple 2nd order at 2khz
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • Gardenstater
    Gardenstater Posts: 4,136
    I think without so much smoothing, the differences between w/ diffraction pad and w/o would be even more apparent. That is a very real improvement though!

    What's with the hump in freq. resp. at around 28 Hz? Is that from the fact that you're not testing in an anechoic chamber?
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
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  • VR3
    VR3 Posts: 27,965
    I believe that 28hz is the room doing something. When I listen to music, there is some definite low bass that makes no sense given what they are. One speaker is pretty close to a corner and the other is pretty far away from other boundaries other than the back wall
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • gp4jesus
    gp4jesus Posts: 1,969
    edited March 2021
    VR3 wrote: »
    All mods up to this point, with diffraction pads, at the listening position
    pv0rbyie5w6r.png

    No diffraction pads
    eid42fe8zzd9.png
    I see a small diff/improvement at 4.5 K - one of the frequencies that tends to annoy
    Samsung 60" UN60ES6100 LED Outlaw Audio 976 Pre/Pro Samsung BDP, Amazon Firestick, Phillips CD Changer Canare 14 ga - LCR tweeters inside*; Ctr Ch outside BJC 10 ga - LCR mids, inside* & out 8 ga Powerline: LR woofers, inside* & out *soldered LR: Tri-amped RTi A7 w/Rotels. Woofers - 980BX; Tweets & “Plugged*” Mids - 981, connected w/MP Premiere ICs Ctr Ch: Rotel RB981 -> Bi-amped CSi A6 Surrounds: Premiere ICs ->Rotel 981 -> AR 12 ga -> RTi A3. 5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”. Power Conditioning & Distribution: 4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s *Xschop's handy work
  • VR3
    VR3 Posts: 27,965
    Indeed, I am also using a revised, oval, diffraction pad versus the round one at the start of the thread.

    So the effect is far different, I will cut one with a round cut out next time I'm doing runs to compare.
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • mhardy6647
    mhardy6647 Posts: 32,926
    VR3 wrote: »
    ...
    The woofer is full range and the tweeter is a simple 2nd order at 2khz

    I was gonna ask :p -- although, that was my recollection. Kind of a funny configuration when running a woofer fullrange, i.e., it was more common to use first order on the tweeter with an un-throttled woofer (a la EPI's "Burhoe Modules"). I guess that whomever designed the Minimus-7 was trying to protect the tweeter near its Fs by using a second order XO.


  • skrol
    skrol Posts: 3,330
    edited March 2021
    This is a neat project and I'll probably try some of this on my 7's as I'm kind of into making lowly or old stuff perform better than it was meant to.

    I see you are experimenting with round vs oval cutouts. Have you considered different texturing? For example, rather than a flat felt surface, concentric channels around the tweeter or other patterns. Kind of like acoustic panels to trap the sound as some may still be reflecting off the flat felt surface. I assume this could be done with the laser.
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
  • VR3
    VR3 Posts: 27,965
    I'm trying something like that with my utopias right now

    Getting to fancy with the laser adds considerable time to its operation. It cuts at the size of the human hair, so getting crazy can add hours to a print

    1vj91xf1ge2g.jpg
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • VR3
    VR3 Posts: 27,965
    kncvzwgx9b2h.jpg
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • ken brydson
    ken brydson Posts: 8,638
    VR3 wrote: »
    kncvzwgx9b2h.jpg

    Guessing it needs to be a bit out from the wall? Lol...
  • VR3
    VR3 Posts: 27,965
    😜

    Big ol coil! Sounds excellent though, from 100hz upx it easily outperforms the definitive monitors I have
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • JayCee
    JayCee Posts: 1,474
    Seeing, in the pic you posted, what the LSi "flame" resistor did to the cap it was mounted on....no worries w/the wood board and heat? Duelund's alone...plus, those have to be the most tricked out Minimus 7's on the planet!
    Speakers: Polk1.2tl's (Uber Mods) Pre/Amp/DAC: PS Audio BHK Signature & 250, DirectStream Cables/IC's: MIT S1Bi-Wire/S1 Balanced +Avel Lindberg 1000VA "Dreadnought" Power Conditioner: PS Audio P15 Power Plant Power Cords: Core Power Technologies Gold, DH Labs Power Plus DIY w/Neotech NC-P301 & P311ends Streaming: Roon ROCK on wifi'd NUC, TP-Link WAP, & Uptone EtherREGEN, AfterDark, Emperor Double Crown Clock, Black Modernize LPS, PS Audio AirLens⟿Ω☯☥☮⟿🔊♩♪♫♬♩♪♫♬♩♪♫♬
  • VR3
    VR3 Posts: 27,965
    edited March 2021
    Nah, I don't see it causing any issues. The burning point for wood is around 400 plus degrees.

    The problem with mounting the caps next to the resistors is that the poly film starts to melt and shrink and it just gets nasty from there!

    The cap you see in the photo is enclosed in an aluminum tube

    Thank you! They do sound great too, dissappear well, great staging and neutral tonality. Great for a desk setup
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • skrol
    skrol Posts: 3,330
    Thread resurrection... So my home office has moved from our sun room to a small room where I can freely listen to my music. I've been auditioning different small speakers in my collection for a desktop system including a pair of LSi7. The setup doesn't do the LSi7s justice with a Parasound Zpre2/Zamp2 and they are too close to me and the back wall. I dug out some Minimum 7s and am actually enjoying them. That of course has me thinking that maybe I would enjoy them more with some mods. Also could use a little sub.

    Have you done anything more with the Minimus 7 Project?
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
  • VR3
    VR3 Posts: 27,965
    I sold my set but I sell alot of the diffraction pads.

    The zilch mod is a must!!

    Great speakers for the $$$
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
  • skrol
    skrol Posts: 3,330
    edited August 2022
    I may be interested in the pads.

    I also found a pair of LX5ii with the Linaeum bipolar ribbon tweeters hiding in my basement. The imaging always gets me. I’m getting lost listening to some old Genesis. However, the bass sounds like dung. Helps to stuff the ports. There are mods out there for these but probably better to scavenge the tweeters for a DIY project.
    o6smffvfh169.jpeg
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
  • skrol
    skrol Posts: 3,330
    I received the anti-diffraction pads for the Minimus 7s today and look forward to trying them out.

    Trey, are these things made from hemp? They kind of smell like somebody tokin' B). I thought my son was ordering stuff off the internet or something.
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Benchmark DAC1, Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW110 , Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7, PSW10 (DXi104 upgrade); Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
  • VR3
    VR3 Posts: 27,965
    Lol, burnt hair smell from the laser 😁
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.