Lowther

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midrange

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Joined 2012
In their "limited edition" line, I was intrigued to see that the AudioVector can be bought as a stereo pair, or as a single monophonic speaker. I have heard a couple of older Lowther speakers as a single speaker, and I really liked them like them. Makes me a bit weird I know.
 
planet10

planet10

frugal-phile™
Joined 2001
planet10-hifi.com
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knarfor said:
I have a copy of the original bass horn drawings.
Click to expand...

Some progress… enuff for peopleto at least get an idea.

Screen Shot 2022-08-25 at 11.00.48.png


dave
 
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wchang

Member
Joined 2009
My 15ohm PM6A (does not say silver coil) requires a notch filter at 8.5khz (0.47mH | 0.68uF to +) to be flat and listenable instead of ear-bleeding. Earlier I had tried doing a "Citation 360" facing upward, the bulb-reflector made from wound felt tape finger-moulded into shape. But that only exacerbated the HF peak (a radial slice overweights the whizzer contribution). Somewhere along the way one driver's vulnerable "innie" foam surround opened a trough. I white-glued the slit using a needle but a year later there's now rubbing noise on sustained deep bass. Maybe I need to rebalance the surround by adding glue 180-degrees away? I had carried them to Beijing ten years ago but they never worked out for me. The Fidelio PM2A Ticonal I found in Singapore always sounded fine -- after I rotated one driver to address a bit of rubbing.... Finicky Lowthers.
 
A

audioscene

Member
Joined 2023
Hi, could you supply a copy to me of the original bass horn drawings you mention, I have background in fine woodworking and would love to make a pair of Lowther Hegerman. I am a user of Solidworks and I would look to complete a 3D file from the drawings, I would then make this work available to any one interested.

Kind regards Barry
 
A

audioscene

Member
Joined 2023
For anybody interested, the PDF contains plans for the Lowther Hegeman Bass cabinet, these are my work taken from original drawings, they were in poor state as they had been photo-copied a number of times, I also have available a Solidworks model of the enclosure, again for anybody interested!

I've had no luck in finding any details concerning the plaster of paris assembly used for the Lowther driver, but of course if anybody could help please come back.
 

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Nelson Pass

Nelson Pass

The one and only
Joined 2001
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wchang said:
My 15ohm PM6A (does not say silver coil) requires a notch filter at 8.5khz (0.47mH | 0.68uF to +) to be flat and listenable instead of ear-bleeding.... Finicky Lowthers.
Click to expand...

My experience is that only a minority of FR drivers cannot be improved by some sort of EQ on the top, but I think it's a relatively small price to pay.

:snail:
 
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M

mp9

Member
Joined 2006
Nelson Pass said:
I have several pair of the PM6A with the overhung silver VC. Among the best of FR and certainly the best Lowthers (IMHO)

:cheers:
Click to expand...
^ which impedance option, the Sliver 15Ω or Silver 8Ω ?
wchang said:
My 15ohm PM6A (does not say silver coil) requires a notch filter at 8.5khz (0.47mH | 0.68uF to +) to be flat and listenable instead of ear-bleeding. Earlier I had tried doing a "Citation 360" facing upward, the bulb-reflector made from wound felt tape finger-moulded into shape. But that only exacerbated the HF peak (a radial slice overweights the whizzer contribution). Somewhere along the way one driver's vulnerable "innie" foam surround opened a trough. I white-glued the slit using a needle but a year later there's now rubbing noise on sustained deep bass. Maybe I need to rebalance the surround by adding glue 180-degrees away? I had carried them to Beijing ten years ago but they never worked out for me. The Fidelio PM2A Ticonal I found in Singapore always sounded fine -- after I rotated one driver to address a bit of rubbing.... Finicky Lowthers.
Click to expand...
^ big difference in Lowther's measurments between Aluminium coil and Silver coil and 15Ω and 8Ω

Silver 15Ω has a flat'ish response plot with a little less than 5dB rise beginning @ ~ 1.7K only a steep drop off top end @ ~ 8.5Khz. The Silver 8Ω is flat within + or - 7dB being recessed from ~ 6.5Hz to 1.7Khz and steep drop off starting ~ 8.5 to 9Khz
Aluminium coil options vary from 8dB to 10dB rise in the upper mids to trebble depending on coil option

https://assets-global.website-files.com/60642ec35aaa96e4388753a3/61430eb78ed96a08cf0dc8cb_PM6A.pdf
 
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Richard Ellis

Richard Ellis

Member
Joined 2006
Over Four-Thousand US dollars per ONE eight-inch full-range driver in a front horn cabinet?? ...Never, you can spout all the "Acousta 117" phoney specs all you want...35 to 20K?, utterly meaningless, how far down in DB is that?, what's the variation?, what, where, how is that "specification" derived?. All hail DIY, so we can all put these "puffed up" manufacturers in their place.

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Rick...
 
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W

wchang

Member
Joined 2009
Nelson Pass said:
My experience is that only a minority of FR drivers cannot be improved by some sort of EQ on the top, but I think it's a relatively small price to pay.

:snail:
Click to expand...
I agree wholeheartedly. My first really successful "EQ of a full-range" was to tame the 5khz peak of Hifi-bird/Isred/Michael's Audio "drum paper" 5.5-inch -- I had meant to listen to a track or two of Bach Goldberg (Celine Frisch harpsichord) but stood listening for 70 minutes to all 30 variations, every note/hand-movement/musical-gesture.

A while ago before I took up speaker-diy during Covid, I had come across your mention of a Lowther notch filter. When I needed it I couldn't find the recipe again, but somewhere else you mentioned taking a few LRC bits and playing with filters. Thus inpsired, I experimented and made my own filters, by now a couple dozen at least, for example here (PM6A, F200A, F108eΣ)
https://www.diyaudio.com/community/...le-city-of-22m-laid-flat.393338/#post-7266571

I can listen to a tone-sweep and come pretty close, doing math in my head. My "minimalist method" for XO and notch-filter (which is XO on a single driver)
https://www.diyaudio.com/community/...ge-drivers-and-a-tweeter.391053/#post-7143129

When I decided to challenge myself on Mark Audio Alpair 10.3 (12dB peak at 7.8khz), I didn't want to be biased by the published chart. (Mark Audio's taobao store has audioclips of instrumental voices, that agreed remarkably well with FR charts good or bad.) After much tweaking and headscratching, I settled on a notch centered at 10khz to my surprise. Turned out, the chart showed a wide plateau 7-14khz (geometrically centered at 10khz dead-on). So I gained a lot of confidence :)

Nowadays the most convenient EQ may be the smartphone.... My old Mi 9 has a built-in hearing test function which culminated in a named PEQ profile for use anywhere. I still prefer the sound of my older Huawei phone (the first truly excellent Chinese phone supposedly designed by the Apple China team -- according to my source), EQ if necessary through a copy of vintage Sharp GF-777 or Sanyo M9998K attenuator-based loudness/tone-control. For speaker-diy testing, I cloud-play my own EAC-extracted WAV files (much more precise and realistically nuanced articulation than FLAC files) through a double-TPA3221 (the one recommended on diyaudio, I bought the last units) with heavy-duty power-brick, OCC interconnects etc.

I'd like to build the "FREQ" but last time through China customs (for Vfet) was quite taxing to say the least.
 
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