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Author Topic: The Fix  (Read 13375 times)

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Offline Paul Joppa

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Re: The Fix
« Reply #15 on: November 10, 2013, 07:44:43 AM »
A small augmantation - I designed the circuit to have a -4dB loss in the midband at all settings. The bass and treble boosts are relative to the nominal -4dB output and are independent of each other.

If you wish to remove the Fix entirely to compare, then you should make the 4dB level adjustment as Doc B described. However, with the Fix in place, you can set both bass and treble to zero dB boost, and make a midband-valid comparison to other settings.

At the flat setting (no bass or treble boost) there are no capacitors in the circuit - only resistors.
Paul Joppa

Offline Chris

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Re: The Fix
« Reply #16 on: November 10, 2013, 08:13:10 AM »
I am a little at a loss with understanding this Fix product..  I have a couple of classics in my collection that I love.. They are immaculate pairs of Acoustat 2+2s (3 pair) and Infinity RS IIIs... The Acoustats have a Big variable resistor for HF level adjustment (would love to remove that if I can for maybe even better sonics) and the Infinity's have an HF level knob in the back... So is the Fix a type of product that could be a better solution?  As Clark said, It may sound better and do a better job than the "inboard" devices built in to the speaker circuit? Or are these speakers the wrong type of designs for the Fix?

Offline Paul Birkeland

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Re: The Fix
« Reply #17 on: November 10, 2013, 08:25:52 AM »
Both of those speakers have internal crossovers.  It's reasonable to assume that both these crossovers have BSC built into them.

You have also stated that both your speakers have HF level control.

Thus your conclusion that this product is probably not useful to you is a correct one.

The Fix is primarily a tool for speaker builders, as well as single full-range driver enthusiasts. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Chris

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Re: The Fix
« Reply #18 on: November 10, 2013, 09:06:30 AM »
The 2+2s are crossoverless, but this doesnt matter anyway because thank you PB!.. you answered my question perfectly.. The Fix is just for the FR single driver type..  Thanks again...

Offline Paul Birkeland

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Re: The Fix
« Reply #19 on: November 10, 2013, 09:17:00 AM »
The Fix is just for the FR single driver type..  Thanks again...

It's not necessarily just for single FR drivers.  If you are deconstructing a speaker to go with an active crossover, this is one of the building blocks that you would need.  Additionally, certain "extremely minimal" 2-way designs will sound way, way better with a line level filter like this than one with speaker level parts inside the enclosure.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Grainger49

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Re: The Fix
« Reply #20 on: November 10, 2013, 10:11:33 AM »
And I was thinking Doc invented the decade box.  But wait!  It has a real audio purpose!

I'm in too! 

BTW, I didn't put you in the group with Dyson who re-invented the air horn, has a fan with no blades (there are 2 million fleas in the base farting to create the air), and advertises it as something new.

Offline Chris

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Re: The Fix
« Reply #21 on: November 11, 2013, 02:59:39 AM »
Ok Thank you PB, I will leave those particular speaker models well enough alone as they are..

Offline Jim R.

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Re: The Fix
« Reply #22 on: November 11, 2013, 01:18:01 PM »
It's probably obvious from the pics, but can I assume that this is a line level device -- between pre and power amps, as opposed to a speaker level device?

Cut-only filters are the way to go, IMO.

I'd love to try this with a buddy's pair of zigmahornets as well as my Nagas.

Cool idea!

-- Jim


Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline Paul Joppa

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Re: The Fix
« Reply #23 on: November 11, 2013, 01:41:16 PM »
Yes indeed - passive, cut only, RC (no inductors).

The impetus for getting involved several years ago was the observation that many home-brew single driver systems needed some baffle step correction, which was (and still is) usually done at speaker level with a choke/resistor parallel combination. This combination reduced the effective midband efficiency to less than half of what it had been, meaning you needed more than twice as much amplifier power. This was a big problem when used with flea-power SET amps, and caused a lot of 45-powered speakers to suddenly need 300Bs. In particular, we were working on the SEXy Speaker at the time, which was being developed specifically to be something affordable that could play loud with a SEX amp. You can still find a very early, non-adjustable version of what became the Fix on that page:

http://www.bottlehead.com/loosep/S.E.Xy%20speakers.html
Paul Joppa

Offline Jim R.

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rRe: The Fix
« Reply #24 on: November 12, 2013, 06:01:05 AM »
So working under the principlle of "there's no free lunch", what are the impedance matching and cabling length considerations with this box between say pre and power amps?

-- Jim
Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline Paul Joppa

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Re: The Fix
« Reply #25 on: November 12, 2013, 09:10:26 AM »
My preliminary spec is the source impedance should no greater than than 4K (the output impedance of Eros, Reduction, and Quickie with PJCCS) and the load should be no less than 100K (the input impedance of most of our amps). Cables on the output are preferably 0.5 meter (1 meter if low capacitance). These impedance restrictions are the price you pay for a passive device.

Final specs will appear with the listing on the product page.
Paul Joppa

Offline HF9

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Re: The Fix
« Reply #26 on: November 12, 2013, 05:54:09 PM »
Very cool, looking forward to trying this with a pair of Frugal Horns :)
My DIY Audio Electronics Blog: DIYAudioBlog.com

Offline Evan

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Re: The Fix
« Reply #27 on: November 13, 2013, 08:27:00 AM »
HF9-
Once you do try it with the Frugal Horns please post your impressions. I am going to be building a pair using Fostex FE126en drivers in the near future and I also thought this might be a worthwhile experiment. Shoot, for the price I could just experiment for myself.
Stereomour => SEOS Fusion 12 Tempest

Crack => Senn HD600

Offline Wanderer

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Re: The Fix
« Reply #28 on: November 13, 2013, 10:03:32 AM »
.... They are immaculate pairs of Acoustat 2+2s (3 pair) and Infinity RS IIIs...

I may be out of my depth but my understanding is dipole speakers do not exhibit a baffle step loss and would not need correction. As I recall Acoustats ae dipoles.   
Kevin R-M

Offline Paul Joppa

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Re: The Fix
« Reply #29 on: November 13, 2013, 10:54:24 AM »
...
I may be out of my depth but my understanding is dipole speakers do not exhibit a baffle step loss and would not need correction. As I recall Acoustats are dipoles.
True - dipoles lose bass for a different reason, and with a different frequency response.
Paul Joppa