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Thread: Bgw amp plus eq for free!

  1. #91
    Senior Member RMC's Avatar
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    CORRECTING THE AT PROTRACTOR

    Took some time to correct the spindle hole size on the AT LP5 cartridge protractor provided (post 85). The too large hole = loosely fitting protractor on TT, simply pissed me off for what is an otherwise ok cardboard tool. Initially thought I could get away fixing this thing easily using adhesive looseleaf reinforcements for binders (1rst pic). Well, the center hole on these is too small at 5-6 mm dia. for a 7 mm spindle, plus didn't really want to do another tedious scalpel job to enlarge those holes: enlarging some to decrease another...

    Last resort idea was to put the protractor on the TT then carefully and equally share the loose all around the spindle, followed by covering the loose spaces around the spindle with small pieces of masking tape, doing that on both sides of protractor. Not sexy looking, but it does the job. The result is a 7 mm hole and a now quite usable AT protractor (2nd pic). I double-checked the results I got with it VS two other protractors (Shure's & Stevenson's) and they match. Despite that, most of the time I still use two protractors when adjusting a cartridge to compare/confirm results. Then the cart should be performing at its best.

    PHONO CARTRIDGE OVERHANG ADJUSTER

    The white plastic "L" shape cartridge overhang adjuster, seen on posts # 88 in the box and # 87 with the 408 cart/shell mounted on it, is the one from the old Technics SLQ2 gone to recycling. Because it holds the shell/cart in place while working on it I still use that adjuster for INITIAL cart setup on shell. This reduces handling of the fragile cart/shell/tonearm directly on the TT, therefore minimizing risks of an accident.

    That small tool (3rd pic) remains relevant here, saves some time and potential needle damage. I noted some guys sell their overhang gauge on E-Bay, same for their Technics clear box SH-98 cart holder previously shown.That adjuster, with 52 mm effective length, is for a 15mm overhang. The last three TTs purchased (SLQ2, LP120 & LP5) required needle overhang adjustments of 15, 16 and 17 mm respectively. So I start with the 15 mm setting indicated on the tip (4th pic), then add just a bit more for 16 or 17 mm as the case may be. Checking the cart is parallel to the headshell is also simple using the overhang adjuster: comparing cart's front line vs shell's front line for example.

    Note at the bottom of the second pic here, AT indicates "Perfect Overhang Settings, OK"circled. What is shown there is NOT overhang setting but rather making the cart parallel to the headshell. Overhang is a distance of where the needle should be located for lower distortion, represented on the protractor by the two black dots inside the lines shown.

    My initial settings with the overhang adjuster are about 90-95% correct for 16/17 mm, therefore only minuscule fine tuning is left to do with the cart/shell in the tonearm & protractor sitting on the TT. Most of the work being already done using the overhang adjuster, prior to moving to the turntable for final adjustment, the latter is a breeze with much less handling to do directly on the TT. The last cart pre-adjusted needed less than a parallel line further adjustment based on the protractors. Did that, done deal!

    Richard


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  2. #92
    Senior Member RMC's Avatar
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    The original 1979 crest audio p-3500 power amp




    I 've wanted to post this for a long time and kept forgetting about it. Seems to me quite a few folks here don't know or remember about this amp which was one of the Pro game changers of the seventies, along with Phase Linear and BGW.

    Touring amp with audiophile sound, hence the "Fidelity Sound Power Amplifier" on the front panel. Crest Audio's founder worked with BGW for some time before designing his own more modern Pro amp than others at the time.

    Tested for Modern Recording Magazine (June 1979 P. 67) by Len Feldman and Norman Eisenberg. Their comments about the amp were quite positive. I can indicate where the report can be found.

    In 1999 Peavey purchased Crest Audio and things changed, like with all those audio acquisitions...

    Unfortunately Crown's response to others eating its lunch (market share) took way too long in my view with model PSA 2 (1990, according to spec sheet date), so many years later than other ones.

    Richard

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  3. #93
    Senior Member RMC's Avatar
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    The peerless "evergreen" tweeter



    With regards to nearfield monitor types I mentioned recently on "Back in the 70's" thread, the following contains some info for the Peerless "evergreen" tweeter as pictured from an old catalogue I have.

    The 1978 purchased Polk Audio Monitor 5 with pretty low serial numbers, are among the first models they released, I still own them and they're somewhat larger than typical small nearfields. At that time a trade magazine test compared the Polk's sound to the Spendor BC-? sound but the latter was said to be short on highs (13-14 khz max). I may add that in a Stereophile review seen the Spendor's tweeter limit was assessed to be extending to about 12 khz. Both reviews indicated the Spendor was missing some very high frequencies, but for the rest concluded they sounded good.

    The Polk doesn't suffer from such lower top end having that widely used Peerless model # 810665 hi-fi "Evergreen" tweeter (frequency response graph below shows its relatively smooth). Its still there up to 18 khz then rolls off. Near the top end, it sounds a little incisive since the tweeter has a small but noticeable peak at about 15 khz which is easily cured with -1 to -2 db EQ, if need be. Depending on program material sometimes I don't mind the peak and other times I do. Also, note from the same graph the tweeter's impedance curve is pretty flat at 8 ohms on a wide range of usable frequencies.

    In addition to the 1" dome, it has a 6.5" bass/mid and 8" passive radiator (both rubber surrounds, they last!). Inputs are on standard binding posts and each driver is fused. A pic shows the banana plug type used to feed the speakers. Fusing drivers, as well as use of passive radiators, were more popular in the old days. I guess Polk didn't want its customers to be overly ambitious power wise on the speakers and blow drivers, hence fuses. They're not very high output speakers, will do 105 db with program material, but nice sounding ones.

    The HF driver was discontinued long ago. A number of known hi-fi speaker manufacturers used this tweeter in their boxes, saw a list of these on the Net. The made in Denmark manufacturing was quality but higher manufacturing costs too. Companies like Polk Audio and others made or found lower cost replacement tweeters for subsequent versions of monitor 5 and others. Binding posts and fusing were also changed later, possibly to reduce cost...

    Tymphany purchased Peerless and Vifa some time ago and moved production to Asia. Though NLA, Parts-Express still has it listed with specs. Mid West Speaker Repair has a copy made of this tweeter they sell and Simply Speakers also sells a replacement copy for $50. Cannot comment on the copies, since the drivers in my pair have never been replaced, the speakers are fully original and in good shape after 41 years.

    The 30-20 khz bandwidth mentioned in the Monitor 5 sheet appears overly optimistic at each end, in practice. Moreover, the "nearly perfect hemispherical dispersion" touted by Polk seems more marketing than real life in view of off-axis data indicated on the Peerless 810665 data sheet here. Also the clean usable response down to the 36 hz resonance of the passive radiator referred to leaves me wondering. I suppose the key is one's definition of "usable". In my view, with reasonable output, its probably 10 hz higher. Giving a real life stand alone bandwidth of about 45-18 khz. Biamping the Polks with the 2214H cabs further improves the low end and makes a nice complement...

    Richard

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  4. #94
    Administrator Mr. Widget's Avatar
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    Evergreen

    I know that tweeter well... I used them in several designs back in the late ‘70s and early ‘80s. It had a pleasant if slightly rolled off sound. If I recall correctly it was available in the $10-$15 a piece range while the Dynaudio D21AFs that I moved up to next were in the $40-$50 range back then.

    Both Peerless and Audax made really excellent drivers that were extremely reasonably priced.


    Widget

  5. #95
    Senior Member RMC's Avatar
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    Hi Widget,

    Thanks for your input here. Always interesting to hear from someone who has much wider view than JBL alone. Though I had/still have high respect for JBL's engineering, which made me purchase three pairs, two I still own, it never prevented me to look at other manufacturers as well. There's some nice stuff from others too, as you have already shown. We're not in the same league, equipment and budget wise, but that's fine.

    In fact I have a lot more non-JBL stuff and this hasn't eroded my esteem for that brand. But at time of choices I also consider other non-performance related variables, such as currency exchange rate, manufacturing country, space available, budget, application, my needs, etc. Ultimate WATTS/SPL often sought on LH isn't really part of my list.

    Btw at 9,999 posts you're just one post away from enjoying a big cigar... Probably will keep reading the next 10K considering their usual practical no non sense approach... Regards,

    Richard

  6. #96
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    Some headshell/phono cartridge issues



    AT distributor stretches my patience. Ordered more than six weeks ago two more AT-HS10BK headshells, like the one with the V15 IV. Learned wednesday they're back order, no date in sight. Digging further I found they have only one left in stock, order for two couldn't be filled, so it was put aside, no call no notice... Still want that single one they have, then I'll even take an AT-HS1 (not as nice & silver) for second one to put the Shure/Radio Shack M75 cart on it. And if the lone HS10BK happens to be gone then its two HS1 (they have 10 in stock). That's it. 6+ weeks wait for what?? Want to sell? Make it happen, get proactive, pronto! Did check EBay and others for good used shells, asking prices are simply crazy, unreal. Better buying new then.

    Had to put the round spacers back on between the AT headshell and the V15 cart otherwise the tonearm wasn't parallel to the record surface (post # 89 3rd pic no spacers on; pic # 875 here they're back on, also showing the 45HE after-market stylus installed and next to it a worn-out Shure original, sniff). Undid prior install/re-mounted the cart with spacers, used the Technics overhang gauge another time, but adding a little more for 17 mm. Checking initial adjustment with protractor on TT indicates no further adjustment needed, surprising! Double-checked with another protractor: same result, no fine tuning to do. First time initial and final adjustments for that TT are the exact same, my lucky day, I'll take it. But...

    Trying the V15 IV revealed the original needle on it has reached the end of its life: the two channels aren't at the same level and the sound is distorted. Stopped it there. Haven't used the V15 for a while since the LP5 came with a cart I wanted to try, and the previous LP 120 also had a pre-mounted cart, plus its tonearm was not worthy of a better cart due to higher friction.

    As mentioned, the new stylus put on temporarily is that after-market 45HE shown. Seen with the small 50X microscope (post # 43) the needle on it looks good. However, upon use I noted the small dust brush (also a record warp damper) built into the stylus frame has too short hair to even work, making that device useless! They say a problem doesn't come alone, so that's another with the too short hair-cut. Mfrg country not indicated on the stylus packaging.

    Fortunately, it can be used with brush in up position (out of service). Still prefer having an ok needle with a poor optional brush than the other way around. Since a hand-held carbon fiber brush is used anyway to remove record dust, plus the Bellari phono preamp has a 20 hz rumble filter taking care of record warp sub-sonic frequencies if any. This way the stylus brush issue isn't a big deal in the meantime.

    Haven't risked yet putting the Shure Micro-Ridge VN45MR on the cart pending I get some new VN45HE replacement stylus, since the MR is now the sole and ultimate genuine stylus I have left for the V15 IV. At least not before I secure some other proper one(s). Looked at LP Gear, some Japan made prospects identified as replacements. Need to order some soon, then I may get rid of that no country/no brush 45HE...

    Richard

    P.S. While re-confirming yesterday the details about the headshells I want (A+B, if no A left then two of B, etc.), since there's still some money in this year's budget, I decided to go ahead and ordered the Behringer DEQ 2496, along with the companion mic ECM 8000, mostly for its RTA feature, and considering its about the only affordable hardware unit left on the market...

    P.P.S. The surrounds of the 6.5" bass/mid drivers shown on the Polk Monitor 5 (post # 93 2nd pic) look more grey, like foam ones, than black rubber stuff. They needed some careful dusting/cleaning with a damp rag, which I now had time to do, to bring them back to their original color. They are now black looking except for the lighting reflection on the pic below, surrounds still quite compliant too. Been using them more these days and will comment on that later (e.g. the Peerless tweeter small HF peak hasn't been an issue with a number of records even with no HF EQ correction).


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  7. #97
    Senior Member RMC's Avatar
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    Sound of v15 iv and at 408 cartridges



    The V15 IV is a well balanced cart, pretty much faultless, does everything competently, but has less "personality".

    With Sun Goddess (live), Earth, Wind & fire 1975 Gratitude LP, Engineering by George Massenburg!! the sound stage is better on the Shure than on the AT. Btw You Tube's version of the song, maybe MP3, is a poor rendering of the sounds and effects compared to the LP record. Sun Goddess is one of the rare popular type music song where I actually much prefer the live version to the studio one, by far. Sax & percussions !!

    The details that went in this recording are brilliant (e.g. channel panning). It has many different sounds coming from the left, from right, some center, different intensities, etc. Its quite a mixing job, raise my hat to Massenburg's work. To confirm what I hear I did a small test with the Mackie's output signal level LEDs, adjusting gains so only the first row of LEDs would light according to channel L/R and music signal intensity, no subsequent LEDs going on, just first stereo pair to avoid any confusion. Room light kept at a minimum for LEDs to be seen easily. The result is evident, watching the L/R LEDs blink its crazy, re how often they're alternating from one side to the other, some centered, plus varying intensity. Naturally LED's follow the music but there's no apparent pattern or definite sequence watching them, great sound effects.

    The AT 408 has more character, not as neutral as the Shure, with a little more emphasis at the top end. Listening to Good Friend, Loggins & Messina 1972, the AT's attack, impact and clarity are impressive for drums, percussions, cymbals, electric guitar notes. Nice.

    The 408 was initially developped for pricier Linear Tracking Tonearm Turntables (P-mount), such TT I never owned and they weren't a big commercial success. An audio store owner had two new ones left, willing to deal he said, checked them for possible fit, AT included a simple finely made adaptor for standard half-inch cart mounting, guy made me an offer one cannot refuse for both. Done deal, 2nd one still stored in its box, all Japan made.

    Overall the V15 IV is a better performer, but the AT 408 still has some interesting aspects sound wise. The properly loaded V15 has a very flat response (typical ± 1 db in 1977 owner manual) and doesn't exhibit that little exagerated VHF sound the Peerless tweeter is supposed to have.

    Quincy Jones, The Dude, 1980 LP. Like his 1989 Back on the Block CD, its also recorded and mixed by Bruce Swedien using the Acusonic Recording Process. Sound clarity exemplary. But this time with the addition of Binaural Recording Equipment. Westlake Audio Studios, Bernie Grundman mastering it, top notch artists too, great album, LOT of instruments, great sound! The Binaural effect is more discernable on smoother and simpler tracks (where less instruments), like voices (The Dude, One Hundred Ways, Somethin Special). Also nice Harmonica & whistle on Velas, plus Piano on Just Once).

    Used the same basement living room temporary audio setup as before (not audio room yet, sniff), carpeted plywood floor, Maple wood wall panels, acoustic tiles on the ceiling. Same usual equipment, but now alternate phono carts, as well as speakers on the small speaker stands I made between the Mission nearfields and the Polk Monitor 5 (nice open mid, no boomy bass).

    When that Polk was released it wasn't marketed as a "look at my specs" or "feel the big bass sound" type of speaker. Instead it was presented as a "worth listening to box and then decide for yourself". No regrets since.

    Listening to three Loggins & Messina LPs 1972-1976 none of these sounded overly bright using the V15IV with proper capacitance loading and the Polk speakers having the Evergreen tweeter. 45HE stylus though, as good tracking HF as the real thing? (Did order a few styluses from LP Gear, they should be on their way).

    The AT 95EX (supplied with LP5) and the AT 408 might have a small high-end peak of their own (no response curve provided), even with proper capacitance load by the Bellari phono preamp, since the V15 used in similar conditions doesn't sound that little brighter.

    Richard

    P.S. Some paragraphs may not be in the right sequence here, wrote that spare time over a few days here and there, no time to check text structure before posting it...

  8. #98
    Senior Member SEAWOLF97's Avatar
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    Richard

    V15T3 has always been my "go to" cart ... have a couple of spares.
    currently have a V15T4 mounted on my daily driver , tho still buying LP's,
    just haven't had time to spin any lately.
    Have a V15V (XLM ?) on my big Denon TT, but it will get transplanted to the
    "new to me" Oracle Delphi, if I ever get down the project list that far.

    Do also have some Empire's (cant recall model - ??) that rivaled the Shures.

    Just a while back I picked up a rare dual platter* Sansui XP-99 (?) that has a
    M91ed and it sounds great. Dont know if the nice quality is from the cart or the TT ?

    TOM

    https://reverb.com/item/20158711-san...-99-1988-black

    *It has a counter-rotating sub platter to kill vibrations.
    “If you think that’s the dumbest thing you’ve ever heard,
    just wait a couple minutes!”

  9. #99
    Senior Member RMC's Avatar
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    Hi Tom,

    Thanks for the comments here.

    You never cease to amaze me with all your great finds. Once in a while I look at your thread showing what you found left and right for very little $, at some point my head starts spinning so have to leave. Also a headphone collector maybe? Where do you see all this stuff? That must be a full-time job looking around? I never see/hear about interesting stuff/deals like you pick-up. Don't really have time searching everywhere, but they seem to be falling on YOU all the time like rain does... Why not on ME the odd time?

    Big Denon TT, Sansui, Oracle,... I got space for one TT only that's it, so it has to be the best compromise I can afford. Phono cartridges are small, don't take space, so I have some of those.

    RE "Do also have some Empire's" I remember the Empire name, my father use to have one on a AR turntable, late 60s or early 70s if I remember well?

    RE "M91ed and it sounds great. Dont know if the nice quality is from the cart or the TT ?" Had one of these on a Thorens way back. Liked it. Good bang for the buck, nice sound. The only issue with many older Shures was their required 400-500pf capacitance load, if not met as with many gear, then the VHF gets more peaky. Not a huge issue but noticeable if too far off. A speaker with some VHF roll-off might make this less evident sound wise. See attached pics re Shure SC35C as an example. At 100pf or so response deviation would be even larger.

    Late 70s I bought a Spectro Acoustics 217R preamp (and 2102 EQ), these were made one State above you by former Engineering colleagues of Bob Carver at Phase Linear. It had user set capacitance settings on the front panel for almost any MM cart, nice. Kept the Preamp about 35 years, still working fine, gave it away to try other things. The EQ, and a BGW amp, were given after about 37 years. Haven't heard about their fate.

    The NAD 3240PE integrated amp I kept provides phono capacitance of 100pf. Add a little more for tonearm wiring and you're ok for popular AT carts at 100-200pf. Not enough for many older Shures though (more recent ones 200-300pf). When purchasing the Bellari phono Preamp, not only did I get a better phono Pre but also getting back the capacitance adjustment lost from the 217R.

    RE Sansui XP-99 Never seen this one before, the platter on that is something, looks very good. Another of your incredible finds I assume.

    RE "if I ever get down the project list that far." Well, we're in the same boat I guess. Always something more urgent to attend than audio, which gets bumped down the list... Sniff.

    Btw Avatar pic looks like a Russian spy to me. Maybe you are after all a Russian spy scouring the USA of all the pre-owned audio equipment deals available? LOL Best regards,

    Richard

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  10. #100
    Senior Member SEAWOLF97's Avatar
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    Hi Tom,

    Thanks for the comments here.

    >>You never cease to amaze me with all your great finds. Once in a while I look at your thread showing what you found left and right for very little $, at some point my head starts spinning so have to leave. Also a headphone collector maybe? Where do you see all this stuff? That must be a full-time job looking around? I never see/hear about interesting stuff/deals like you pick-up. Don't really have time searching everywhere, but they seem to be falling on YOU all the time like rain does... Why not on ME the odd time?

    Big Denon TT, Sansui, Oracle,... I got space for one TT only that's it, so it has to be the best compromise I can afford. Phono cartridges are small, don't take space, so I have some of those.

    Richard<<

    we are empty nesters , raised 2 kids here ... now just us two bouncing around. Good income, retired 17 years and I cycle and collect gear ... stuff that isn't up to what I need gets passed on (usually paying for much more than itself) . have more headphones than I can count. A home theatre system , big music system, 120Ti's on the computer and 2 big systems in the living room and a smaller one to demo speakers on. Oh, and 1 in my work area. and about a dozen DAP's , oh yeah, and a Creek amp for headphones on the bedstand.

    http://www.audioheritage.org/vbullet...l=1#post425912

    Quote Originally Posted by RMC View Post
    Big Denon TT, Sansui, Oracle,... I got space for one TT only that's it, so it has to be the best compromise I can afford. Phono cartridges are small, don't take space, so I have some of those.
    5 active TT's ... The Oracle is waiting to be #6 . My son sells records online and so I've gotten into the habit of buying anything interesting ..keep some, ship others to him.

    Quote Originally Posted by RMC View Post
    Late 70s I bought a Spectro Acoustics 217R preamp (and 2102 EQ), these were made one State above you by former Engineering colleagues of Bob Carver at Phase Linear.
    RE Sansui XP-99 Never seen this one before, the platter on that is something, looks very good. Another of your incredible finds I assume.

    Richard
    I have a Spectro Acoustics amp somewhere in storage.
    another minidisk deck yesterday.
    http://www.audioheritage.org/vbullet...l=1#post426010

    Quote Originally Posted by RMC View Post
    Btw Avatar pic looks like a Russian spy to me. Maybe you are after all a Russian spy scouring the USA of all the pre-owned audio equipment deals available? LOL Best regards,
    Attached Images Attached Images  
    “If you think that’s the dumbest thing you’ve ever heard,
    just wait a couple minutes!”

  11. #101
    Senior Member RMC's Avatar
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    Mission small nearfield speakers



    Use these often, the Polks too, for reasons of limited space with temporary audio setup. Bought them new in 1991, vented box, 5.25" bass/mid Plasiflex cone and 3/4" fabric dome tweeter. Response rated 70-20 khz ± 2.5 db, and - 6 db @ 60 hz. Recommended amp 20-75 W /ch.

    Looked quickly at some L series JBL consumer speakers Tech Manuals I have (L7, L15, L100T, L100T3, L101 Lancer, L150A, L212) to see how they rate box frequency response. Only two of those had a response rating with ± db, the L7 and L100T3, and in their case its ± 6 db.

    These small Missions have some common grounds with nearfield monitors: deeper than wide for improved imaging, tight frequency response rating, also with some older nearfields since when the box is correctly oriented the tweeter is down and woofer is up, in order to have the HF unit at ear level when sitting, either at a console or on couch with speakers on higher stands. Correct positioning is confirmed by the Mission name on tweeter, also by Made in England at the bottom of the cabinet (see pic).

    During older days it was more frequent to see nearfield monitors sitting "up side down". Presently, the Missions are on small stands I made, tweeter is up to avoid having it too close to carpeted floor absorption. More recently some nearfields use HF wave guides (e.g. Genelec, JBL). Nearfields are also optimized for flatter LF response with 2 Pi placement or with 4 Pi placement, as explained by Eargle (Handbook of Sound System Design, P. 294).

    The manufacturer here doesn't say specifically in manual if its 2Pi or 4Pi designed (many don't), but the Missions are probably closer to a 4 Pi design, as can be inferred from some mentions below. Plus according to my own experiments they sound too bassy woofer down directly on the floor (2Pi), a clue towards 4 Pi.

    What differentiates the Missions from many others is they're optimized for smooth power response (off-axis), instead of the more usual on-axis: "The loudspeakers are designed for an extremely smooth 'off axis' frequency response performance. This means that they are not to be 'toed in' or angled towards the listener." (re positioning) "... with their fronts facing straight out." Mission adds the model "should not be placed directly on the floor ... or in the corners of your room." (Owner Manual, P.3) But they can be used on stands, bookshelfs, even console top. More clues in the direction of a 4 Pi design.

    Moving to the left or right in the room, not far from the speakers, leads to very little sound difference, up to a point as they're not omnidirectional, but certainly show less difference than with the Polks having the Peerless tweeter. Tried toe-in just for the sake of it, not as good sounding, imaging blurred.

    Their 4 Pi or so and good power response may be what gives the listener an impression of the boxes sounding somewhat larger than they actually are. Like in post # 84 when wife came downstairs saying I was overpowering her own music...

    Before letting go the BGW 100B amp I tested it again prior to shipping to make sure it worked ok. I used it to power these Mission nearfields, which were driven up to the onset of clipping at some point. Then click, nothing. Busted speakers? Thought it wouldn't be such a nice cut-off with no apparent sign of speaker distress. Thermal issue then, amp being warmer than usual!

    Shut it down, waited few minutes, turned-on amp again, played some more music up to about half power this time, amp delivered as if nothing ever happened. That kind of confirmed the theory of a thermal trigger re full power used and warmer amp. Never got this issue before, don't normally go for pedal to the metal power output, but wife was gone shopping...

    At the time I didn't suspect a better reason re protection trigger (dumb me i guess, but didn't launch a "national investigation" for that). Stayed that way up until many months later when looking at Eargle's "Recording Monitor Loudspeakers" section in his Loudspeaker Handbook, P. 200. Broadly speaking he says, Eargle gives a list of monitor speakers attributes: "7. Well behaved impedance characteristic. The DC resistance of the system should not drop below 80% of the nominal impedance value,..." That's where the light turned-on re circuit trigger. Sure failed to check system DCR on the Missions before.

    Pretty confident a lot of folks here may not have done that either (in absence of an issue). Plus on LH forum DCR is way more associated with driver(s) alone, than at system level. Also, many modern amps in use today have pretty low impedance capability, wasn't like that during 100B time.

    The Missions have 6 ohm nominal impedance and a measured system DC resistance of 3.6 ohm assessed with a precise multimeter (1% accuracy). Not so "well behaved" on that aspect, pretty low DCR at 60% of nominal figure, 80% would give 4.8 ohm (Btw the Polks measured a nicer 7.3 ohm). On the other hand, the 1979 BGW has a minimum impedance rating of 4 ohm, and actual factory test at clip was 80 W @ 4 ohm. Being driven at the onset of clip when the cut-off took place, I now believe the amp's sensitive protection circuit triggered because of excessive current draw, also creating more heat, in view of the above DCR.

    But the little boxes survived harmless. Learned from it what they have in the stomac. Sure won't rattle the silver with these speakers, never been the intention anyway, but they do sound good, their power response giving them a little something extra. Bi-amped with LF cabs further increases the pleasure.

    Richard

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