Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => The Fix => Topic started by: Doc B. on November 07, 2013, 02:15:09 PM
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Yup, we snuck a new product in the lineup. This is a passive baffle step corrector and treble compensator kit. The box has a pair of inputs, a pair of outputs and four switches with attendant network components attached.
One pair of switches controls an adjustable baffle step corrector that compensates for the bass rolloff inherent in narrow baffle speakers. One switch is used to set the appropriate bass turnover frequency for the baffle width of the speaker you are using - under 6", 6-12" or over 12". The second switch controls the magnitude of cut of frequencies above that, to effectively create a passive bass compensation which flattens out what is normally a falling frequency response below the baffle step frequency. Magnitude settings are 0, 2 and 4 dB of bass compensation.
The second pair of switches similarly allows the ability to compensate for the treble rolloff often experienced with full range drivers. One switch selects a turnover frequency of 5kHz, 10kHz or 20kHz, and the second switch chooses 0,2,or 4 dB of treble compensation above that frequency (again, since this is a passive device what is actually happening is that the spectrum below the turnover frequency is being cut).
We used this with our pair of Orcas, set to +2 dB at the narrowest baffle setting (6" or less) for bass boost and 10kHz and 2dB boost for the treble compensation. It creates quite a remarkable livening up of the sound without adding any bloat or harshness. There is of course the impression of a bit lower playback volume due to the small loss of the passive networks, which is compensated for by turning up the volume on the amp or preamp. What is the effect? Suffice it to say that this box will be staying in our Orca/Dungeness/Stereomour system, and another will be going into my Orca based home theater setup.
As you can see the kit will be offered in a form similar to the Quickie preamp, built on an acrylic panel with the option of adding one of our wood base kits to your order. Kit price will be a most reasonable $75.
While we used the prototype with Orcas, the kit should be useful for a broad range of speakers. If you have a mid/bass driver in a small box and a separate tweeter, you can leave the treble compensation set at zero to eliminate it from the circuit and just take advantage of the bass compensation. And vice versa - for example if you have a horn tweeter that is great but flagging a bit above 10kHz you can zero the bass circuit and just apply the treble compensation. It should make for a really versatile tool for ekeing the last bit of goodness out of your favorite speakers - and maybe even make some doggier speakers hunt a little better.
The guys should be shooting the assembly manual next week, and I will have an order page up ASAP.
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Another winner! Count me in for one!
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I'm in.
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Add me to the list...it should be interesting to see what it changes on my horns.
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The look of this thing was reminding me of something. I finally figured out what it was, a Genrad decade...
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Faz413224.vo.msecnd.net%2Fimg%2F24784%2Fm_s_p_24784_1.jpg&hash=f2e474f560071c738177aba86caa399f5e097245)
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The technical details on this one are far over my head. Can anyone say whether this would be beneficial to my set up (see below).
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Can this enhance wider baffle speakers like my JE Labs OBs? Drivers are vintage ALTEC 756B and Jensen RP302. Thanks.
Gerry
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Can this enhance wider baffle speakers like my JE Labs OBs? Drivers are vintage ALTEC 756B and Jensen RP302. Thanks.
Gerry
The best answer is, we don't know. Is the speaker rolled off above 5K? or 10K? Does it seem to be lacking below 500Hz? If so, the Fix might do something positive.
The Fix was developed as an assist for full range drivers in narrow baffles, narrow generally meaning 12" wide or less though the effect does not simply stop at greater baffle widths, and full range implying that there is usually a little bit of treble rolloff as a driver characteristic. So if a speaker is rolled off in the upper to mid through deep bass and/or rolled off above 5K,10K or 20K then the Fix might help.
If it's not possible to determine this from listening experience it might be beneficial to measure the response of the speakers so you can make an informed decision.
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I may try it for the WE. They start to roll off around 12/15k I think. My baffles are more than 12" wide so probably not needed down there.
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Some drivers have a slowly rising response between 200-1000Hz - the older JBL D130s, for instance. Also, open baffle speakers loose some bass relative to an optimal sealed or ported box. A bit of boost down low might help in those cases.
You can read a ton of stuff on the web about baffle step. The effect on-axis in an anechoic environment is 6dB, but there is wide agreement that (well-designed) real speakers in real rooms never need more than 4dB. In case anyone wonders why there is no 6dB setting.
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Have already gotten a few questions about the fix. I did get to hear it the other day and I think iits a darned fine solution for those folks who need one.
I've played with EQ extensively in a wide variety of forms and various systems.
The verdict? It depends on the room, listener, the speaker as to whether or not eq is used. I find myself using eq permanently less than 1% of the time in any speaker. My design ethic: It has to cut the mustard with its own acoustics via a good speaker/amp/room pairing or else i just wont listen to that speaker.
However, in our listening space, im able to have total freedom with placement, especially the rear wall distance to accurately tune the bass rolloff, and the room itself is definitely in the "good sounding" category. So I find that no eq on the Orca is the ticket for my daily listening even with as many eq devices I have available to use potentially. However, when I put them in weird places in the room, pull them out pretty far, or etc, (things you probably should experiment with given a speaker that's as small as this is and can be put into so many different room circumstances and still sound good). For the vast majority of Orca users, it seems that the flatness of frequency response is rarely a concern, more that they can only get so loud being a 3" driver and that this limitation in upper colume capabilities either works for you and your listening habits or it doesnt.
If you are significantly challenged in room placement, have a very "live" sounding space, or if you have natural or unnatural forms of hearing loss in the high frequencies you should definitely consider The Fix. The pre level form of eq is synergistic with Bottlehead's pre amps. The treble boost is better sounding than adding most any $75 pair of tweeeters. Its still a point source.
Any eq is a tradeoff in terms of overall sonics but the fix has tradeoffs that i could live with. (very very very slight loss of "energy", but way less coloration than any kind of "in box" speaker level bsc network). I think a cool tweak for alot of commercially available FR speakers would be to yank out the speaker level BSC and instead use the fix...
We will also be releasing some new speakers soon that will have a slightly less relaxed and "young person ears" kind of treble and bass character to them. But they wont be $75 a pair...
Hope this perspective helps!
Clark
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Speaking of coloration, of course at $75 there's no way super boutique capacitors are being used!
I figure that once you find the best settings, you can swap out those caps for something better. In fact, you could simply replace the ones on the unused settings, allowing you to compare capacitors. And of course you are not "stuck" with the baffle width or HF boost frequency settings. I'll probably write up a page with the formulas some day, but by far the best option is to listen, and if you feel you really need an intermediate setting then split the difference on cap values.
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Speaking of coloration, of course at $75 there's no way super boutique capacitors are being used!
For all positions except the widest baffle width setting, we are using polystyrene film caps. There are many, many "boutique"caps that I wouldn't consider an upgrade to these.
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I will be in too!
Nice idea!
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I want to start by saying I did not mean to imply that the Orcas need the fix. They happened to be one of the speakers we use and love at work, and our listening room setup is not optimal for them (Clark's room sounds a lot better) so they were the victim of our experiment. I'm also going to back PB up that the Polystyrene caps are pretty good and I imagine that the changes to other caps might not always be worth it.
There is a fundamental thing that needs to be considered when discussing the change of sound as a loss of detail or whatever. The Fix is designed to increase the level of the frequency extremes. Ipso facto the midband becomes relatively lower in volume. There are two ways to look at this - the Fix has reclaimed lacking deep bass and upper treble, or the speakers have lost midrange presence relative to the un-Fixed system.
The Fix is passive and thus there is no boost anywhere. To get the deep bass and high treble up you do in fact cut the mid band level. So to bring everything back into a condition where you can compare the sound to un-Fixed you do have to turn the volume up a bit to get the midband back up to where it was. In other words if you use the 2dB switch setting you need to increase the volume 2dB.
If you throw the switch to 2dB or 4dB and do not adjust the level accordingly you aren't really doing the most logical comparison.
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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.
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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?
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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.
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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...
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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.
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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.
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Ok Thank you PB, I will leave those particular speaker models well enough alone as they are..
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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
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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
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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
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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.
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Very cool, looking forward to trying this with a pair of Frugal Horns :)
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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.
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.... 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.
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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.
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Paul,
I've purchased one for my Frugal Horns, I also have a pair of SeXy Speakers, will the settings overlap the BSC previously put out for the SeXy speakers so I can remove my inline one?
Alonzo
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I've gotta chime in here one more time to say that I've tried out alot of caps for high frequency tasks like single component tweeter crossovers with some super high end Fostex drivers (FE208ES-R and T90A-EX). I eventually abandoned the tweeters, BSC, or, really, any treble adjustment because I couldn't find a cap, resistor, l-pad, etc. that sounded "right" for the tweeter.
That is, until I heard The Fix with the Orcas. The sound of those polystyrene caps doing their job at the line level was so effortless and transparent that I just don't see a way of getting a tweeter to work out as well unless it was way higher end than even the T90A-EX or something. Paper cone highs can sound really natural and smooth, but are always locked in exactly the same proportion with the rest of the fullrange driver and/or often become directional the larger you go in cone diameter. Metal tweeters just tend to sound, well, metallic to me no matter what, and ribbons are nice, clean and sound really "deep" to me in a good way, but seem to outpace most of the direct radiator woofers that they are mated to. Overall, there are so many compromises out there. I could go on and on, but suffice it to say that I think it is really tough to "tweet."
The Fix is a really compelling tweak for me as an FR guy because I can just get more highs from my favorite driver if I needed to. For that matter, its great for anyone who needs a different frequency response from any old speaker, Orcas or otherwise. For instance, for speakers with the "bad sounding" kind of speaker level HF and LF boosts, you could zero those out, and use The Fix instead... Lots of possibilities. I really wish I had The Fix back when I was listening to Fostex 6" ers - Fantastic drivers in many respects but rolled off in the highs to my ears.
Cheers!
-Clark
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Will this be out (delivered) in December? I anticipate another government shutdown come January so I'm lining up my projects...
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..., will the settings overlap the BSC previously put out for the SeXy speakers so I can remove my inline one?
Alonzo
Yes indeed, it is the same circuit except for having more control. Even for the SEXy, I strongly recommend trying all the settings to find what works best in your room. (Also the Fix has some pretty nice caps, chosen by PB.)
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We are waiting for some parts to arrive and then the guys will shoot the manual. Once that is ready we will begin shipping, probably in a week or two.
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I'm looking forward to the comments from the community when this is released. I'm especially interested in how they work with Orca's. I personally don't think that the Orca's need Baffle Step Correction like my former speakers (SEXy). However I'm currently set up in a "sonically challenged" room. I'm thinking that "The Fix" might be able to correct some of my room anomalies that I'm unable to solve with room treatments. It certainly is a very affordable way to find out.
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Hi,
This seems quite interesting. Somehow, it reminds me a bit of this design used on old Quad preamps. I may be wrong on this though.
So my actual set-up is a SEX purchased and built in 2006 (I suppose that is a 2.0?) which had an iron upgrade (aka "enhanced SEX"). The amp is connected to a pair of Fostex 206 ES-R (http://www.einklang-audio.com/treiber/fostex/fe206esr.pdf).
Now, the lower frequencies of the Fostex are decreasing 'seriously' at 200 Hz (see attached tech document). I have connected a subwoofer driver (an Augie Silver Iris) to compensate for the lack of bass.
So if I understand correctly, using The Fix, I could go as far as changing the cut-off frequency of the Augie to a lower level because I might raise the lower frequencies db on the Fostex'?
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I'd set the Fix on the widest baffle setting and +4dB of BSC. This should certainly help with your setup.
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The linked specifications are probably with an IEC standard baffle, which is a largish open baffle, and driven by an amp with a very high damping factor. If you have an enclosure, it will significantly alter the response below 200Hz; the usual design goal is to make it flat to as low a frequency as possible.
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I'm thinking that "The Fix" might be able to correct some of my room anomalies that I'm unable to solve with room treatments. It certainly is a very affordable way to find out.
Dear Natural Sound; If you got a "FIX" could you report on how your Orcas responded to the corrections available?
Cheers, Hank