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 Post subject: Heil AMT resurrection
PostPosted: February 28th, 2013, 4:16 pm 
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With ESS beginning to produce Heil AMTs again and Parts Express selling them I decided to resurrect an old pair of speakers I built years ago to be the basis of an article I plan to write for "AudioXpress". They have original Heil AMTs for the top, Eton 7" Hexacones for the mid and currently HSU 12" woofers.

The Heils and Etons are excellent if you use them properly. Both are great within a certain range but get very nasty if you get too far out of their prime bandwidths. Using an electronic crossover with LR 48 dB/octave slopes fills the bill.

The HSUs are good drivers, but PE has a new 12" driver that looks very interesting. It is called the Ultimax DVC and has some very interesting specs. the Xmax is 19 mm which is very good for a reasonably priced 12". The two voice coils are 2 ohms each so you can get 1, 2, or 4 ohm impedances. They have lots of other design goodies which can be found on the PE website. I have a pair on order and hope to get them soon.

Electronics I'm using for test include a Sony DVP-NS500V SACD player, an NAD 1300 pre-amp (this is the discrete old version that is quite good), a Behringer DEQ2496 digital equalizer, a Behringer DCX2496 digital crossover, a modified QSC USA1300 amp for the lows, a modified Hafler DH500 amp for the mids and a Parasound HCA 800II for the top.

I have started voicing the system using the HSUs and after a lot of work the results are very promising. The sound stage is exceptionally deep, the transient response is excellent, and the detail is great while not being etched. The bass is good but limited in performance compared to the mids and highs. Crossover points are 200 Hz and 1 KHz. The 1KHZ is no problem for the AMT with the 48dB/octave crossover slope. I'll continue the voicing when the new woofers arrive. Photos are enclosed.


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Heil electronics_small.jpg
Heil electronics_small.jpg [ 70.31 KiB | Viewed 34030 times ]
Heil prelim_small.jpg
Heil prelim_small.jpg [ 106.23 KiB | Viewed 34030 times ]
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PostPosted: March 4th, 2013, 8:39 pm 
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The woofers arrived today from Parts Express. Here are some photos of them and the HSU woorers they will replace.


Attachments:
File comment: UM12-22 cone with Nomex honeycomb and fiber glass
UM12-22 top_small.jpg
UM12-22 top_small.jpg [ 644.24 KiB | Viewed 34016 times ]
File comment: Tinsel leads as part of the spider to reduce chance of breakage at high excursions
UM12-22 tinsel leads_small.jpg
UM12-22 tinsel leads_small.jpg [ 993.17 KiB | Viewed 34016 times ]
File comment: Side view showing heavy duty terminals. Note "Tall-boy" surround
UM12-22 terminals_small.jpg
UM12-22 terminals_small.jpg [ 372.9 KiB | Viewed 34016 times ]
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PostPosted: March 4th, 2013, 8:44 pm 
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Woofer photos 2


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File comment: Bottom view
UM12-22 bottom_small.jpg
UM12-22 bottom_small.jpg [ 440.2 KiB | Viewed 34016 times ]
File comment: Top cone intermediate fastening to voice coil
UM12-22 Cone rear fastening_small.jpg
UM12-22 Cone rear fastening_small.jpg [ 1.27 MiB | Viewed 34016 times ]
File comment: Under spider vents
UM12-22 under spider vents_small.jpg
UM12-22 under spider vents_small.jpg [ 598.61 KiB | Viewed 34016 times ]
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PostPosted: March 4th, 2013, 8:47 pm 
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HSU photos


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File comment: HSU top view
HSU 12 in top_small.jpg
HSU 12 in top_small.jpg [ 573.31 KiB | Viewed 34016 times ]
File comment: Side view showing flocked paper cone
HSU 12 in side flocked cone_small.jpg
HSU 12 in side flocked cone_small.jpg [ 395.93 KiB | Viewed 34016 times ]
File comment: Terminals and free floating tinsel leads
HSU 12 in terminals and tinsel leads_small.jpg
HSU 12 in terminals and tinsel leads_small.jpg [ 618.22 KiB | Viewed 34016 times ]
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PostPosted: March 12th, 2013, 12:19 pm 
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Joined: March 12th, 2013, 11:45 am
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Location: Glen Burnie, MD
Tom, What a cool project. The new PE woofers look killer. I look forward to getting a chance to hear them after you have voiced the new woofers into the system.
Regards,
Kemper


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PostPosted: March 15th, 2013, 1:33 pm 
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The voicing is going faster than expected. This should be finished in a short time. Here is what it looks like now.
Attachment:
File comment: Complete speaker showing drivers
complete speaker oblique_small.jpg
complete speaker oblique_small.jpg [ 375.39 KiB | Viewed 33998 times ]


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File comment: Complete speaker with grille
Speaker with grille oblique_small.jpg
Speaker with grille oblique_small.jpg [ 454.69 KiB | Viewed 33998 times ]
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