Bottlehead Forum

Other Gear => Speakers => Topic started by: Doc B. on October 15, 2009, 02:24:13 PM

Title: Straight 8 - the original Bottlehead speaker kit
Post by: Doc B. on October 15, 2009, 02:24:13 PM
This was great bang for the buck speaker, but difficulties with the supply of various parts forced it onto retirement. Perhaps the coolest part was the cabinet kit that assembled like IKEA furniture. Unfortunately the original plans disappeared when we lost an old hard drive and somehow we never backed them up! If anyone has the original instructions and can send scans we will post them here.

http://www.bottlehead.com/straight%208/straight_8.htm (http://www.bottlehead.com/straight%208/straight_8.htm)
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: Geek on October 15, 2009, 03:33:06 PM
Sure is a sharp looking unit.

Sorry to hear of your data loss.

Cheers!
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: Wrinkles on October 15, 2009, 03:53:10 PM
Doc,
Could you post the last crossover designed for the straight 8s? I still love these speakers.
Michael
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: Doc B. on October 15, 2009, 04:06:56 PM
Quote
Could you post the last crossover designed for the straight 8s? I still love these speakers.

Actually I did, sort of - at least for the stock tweeter. Follow the link to the Straight 8 page, and it will direct you to a page with info on the last crossover.

We did a couple of other iterations, one with a horn tweeter and one with an Aurum Cantus ribbon tweeter. I think the info is probably in the old forum archive. It would be great if someone tracked it down. I would be happy to post the info here if you send me a link to the original post.
Title: The ART Array seems to be a cousin
Post by: booangler on October 16, 2009, 02:10:38 AM
Hi all,

I have been thinking about building the ART Array (http://fredt300b.smugmug.com/gallery/2046580/1/105115855#106644141_6xpLK-A-LB) as a Winter Project. I was surprised to see how similar the Straight 8 and the ART seems to be. I am wondering if the Climax crossover might work in the ART?

Alan
Title: Art array
Post by: Doc B. on October 16, 2009, 05:10:25 AM
Possibly a cousin, but I'm afraid the DNA of the drivers is enough different that it would need it's own crossover design. The Straight 8 crossover addresses some warts that are peculiar to the drivers we used, and thus an optimized crossover for the ART array would need a crossover that addresses it's drivers' peculiar warts. Might be close, but not optimal.
Title: Re: The ART Array seems to be a cousin
Post by: Paul Joppa on October 16, 2009, 07:00:55 AM
...I was surprised to see how similar the Climax and the ART seems to be. ...
(Of course you mean the Straight 8, not the Climax.)

Towards the end of the development chain of both designs, I wound up targeting the same acoustic crossover for both Straight 8 and Climax - fourth order Linkwitz-Riley at 3150Hz. In all cases (tweeters and woofers, Straight 8 and Climax) the individual drivers have responses that are not flat so the crossover electrical response plus the driver response works out to the target acoustic response. Therefor none of these crossovers are suitable for different drivers.

Here's a rundown on the various drivers:

Straight 8 midwoofers - the original drivers had a curvilinear cone; they were replaced without warning by the supplier with straight-sided cones at some point. This made a difference in the treble response. Various thin coatings were used on the woofer cones to damp the very high frequency ringing (an octave or two above crossover); the best of the coatings was discontinued - again without warning - by the manufacturer. The most recent published crossover is the best we have come up with.

Climax midwoofers - again, the original Eminence driver was discontinued. It had great promise, though the small excursion meant it needed a subwoofer like the SEXy Speaker design. The published crossover was quite good, matching the L-R amplitude and phase remarkably well to more than an octave past the crossover point. These were tough drivers and needed extensive break-in to perform at their best.

Straight-8 dome tweeter - this titanium dome has some problems with limited excursion (making it more fragile than the very sturdy woofer array) and a 20kHz resonance, but was otherwise very clean. The most recent published crossover included a 6dB trap to kill the resonance. The limited excursion makes it a little rough when pushed too hard, but at normal levels it works quite well. (Normal levels means Mahler is OK but Nine Inch Nails is not.)

Climax horn tweeter - This little Selenium is very tough, but it needed a lot of help. The response is far from flat, and the horn mouth reflections and cabinet scattering are quite severe. The crossover is fairly complex, and very different from a classical theoretical crossover. And the horn modifications described in the published design are essential to use in conjunction with the crossover; neither one alone is suitable. But combined, the amplitude and phase response is remarkably close to the design target.

Aurum Cantus ribbon - we tried many times to make this work, mostly in the Straight 8 but with the intention of using it with the Climax as another option. The difficulty was a huge resonance around 1700Hz (if I recall correctly) which is quite audible because it is right in the middle of the midrange where the ear is most sensitive. The last crossover design I made for it had a big notch to correct teh resonance, but it did not work as intended and did not alleviate the sonic problem. In addition, the ribbon was very easily damaged by testing (we blew out a number of them) and a half hour of Nine Inch Nails through a Paramount was enough to make the ribbon sag visibly. So I gave up on it, there is no crossover I can recommend. A very airy tweeter, I would not hesitate to use them as a supertweeter crossed at 8kHz or higher, second order or steeper.
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: Doc B. on October 16, 2009, 07:59:46 AM
I think the resonance of the Aurum Cantus G2si (is that right?) was higher than 1700. I want to say it was more like 2200. Or maybe that was just what we accidentally designed for and why the notch filter didn't seem to work too well... Anyway when it comes to ribbon tweeters, even at 5 times the price I would say the RAAL ribbon is worth the difference.

Title: Straight 8 kit cabinet assembly
Post by: Doc B. on October 16, 2009, 08:32:11 AM
Thanks to Michael for digging up this nugget on Straight 8 kit cabinet assembly

http://www.bottlehead.com/straight%208/cabinetassembly/straight8cabinetkit.htm (http://www.bottlehead.com/straight%208/cabinetassembly/straight8cabinetkit.htm)
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: glynnw on October 18, 2009, 11:01:03 AM
I still have the original plans and will try to shrink them from 11x17 to 8 1/2 x 11 so I can scan and email them.  I won't know if they will be legible at this smaller size until I try it.  FYI, the woofers, MCM # 55-1870, are on sale at MCM for 8.95 each for the next week or so.  I have been in the process of comparing 3 speakers;  Straight 8 w/Selenium tweeter, Basszilla and Klipschorns.  Have already decided the Klipschorns come in last place, but still trying to figure out the other 2.  The Basszillas are by far the bass champs of the 3, not because they are overpowering, but because the bass notes are very distinct and accurate. You can really dissect drum recordings because you hear the skin as well as the boom.  But the vocals are another story.  I listen to the basszillas for a couple of days and then swithch to the Straight 8s and just relax more while listening.  Perhaps it is simply that I am more familiar with the sound, but I really think the Straight 8s just do something that is musically right that has nothing to do with detail retrieval or tone quality.  I should also point out that by now the crossover parts in the Straight 8 are almost all higher quality than those I used in the Basszilla.
Title: Re: The ART Array seems to be a cousin
Post by: dbishopbliss on October 19, 2009, 03:11:29 AM
Hi all,

I have been thinking about building the ART Array (http://fredt300b.smugmug.com/gallery/2046580/1/105115855#106644141_6xpLK-A-LB) as a Winter Project. I was surprised to see how similar the Straight 8 and the ART seems to be. I am wondering if the Climax crossover might work in the ART?

Alan

I will be cutting the panels for my ART Array's on Tuesday night.  Then, starting on cutting all the holes!  I'm very curious to listen to an array speaker.  Hoping to have them complete for the next local meet.

David
Title: Glynn's ST324 crossover
Post by: 2wo on October 22, 2009, 06:13:01 PM
This needs to go here, 

http://db.audioasylum.com/cgi/m.mpl?forum=bottlehead&n=135255&highlight=crossover&r=

Doc, what is the best way to submit something like this?

...John
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: Rick Rigler on October 23, 2009, 03:44:02 PM
I have been in the process of comparing 3 speakers;  Straight 8 w/Selenium tweeter, Basszilla and Klipschorns.  Have already decided the Klipschorns come in last place, but still trying to figure out the other 2. 

Wow! Wanna trade the Klipschorns for my Straight 8s with the V3 crossovers? With all due respect to the S8. It is a great speaker!

Rick
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: Dr. Toobz on October 23, 2009, 06:10:15 PM
I wish I had gotten into Bottlehead stuff before the Straight 8 kits went extinct. The idea of tube-friendly speakers that don't require woodworking (for those of us with no place or tools to do so) and assemble like Ikea furniture is very appealing. I'm really running into problems finding speakers that look nice, sound good, and will present an easy load to my 2W S.E.X. amp. Klipsches seem to bleed my ears, single-drivers seem like over-glorified midranges being asked to play bass and treble, and anything else is too expensive for my budget. I listen almost 100% through headphones as a result.

How much was a pair of Straight 8's as of 2004 when they were discontinued?
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: Grainger49 on October 24, 2009, 02:47:22 AM
I wish I had gotten into Bottlehead stuff before the Straight 8 kits went extinct. The idea of tube-friendly speakers that don't require woodworking (for those of us with no place or tools to do so) and assemble like Ikea furniture is very appealing. I'm really running into problems finding speakers that look nice, sound good, and will present an easy load to my 2W S.E.X. amp. Klipsches seem to bleed my ears, single-drivers seem like over-glorified midranges being asked to play bass and treble, and anything else is too expensive for my budget. I listen almost 100% through headphones as a result.

How much was a pair of Straight 8's as of 2004 when they were discontinued?

You have hit many of the shortcomings on the head.  But those are generalizations.  Not all full range drivers are glorified midranges, not all horn speakers shout at you.  To get really deep bass you need a sub woofer.  That is pretty much true regardless of the power you have available. 

With no woodworking available (me too) and a limited budget there are only a few speakers out there.  Since this is the Straight 8 thread you should start a thread just for suggestions under this heading?

Doc's old site had a list of tube friendly speakers but I can't seem to find that now. 
Title: Straight 8 plans
Post by: Doc B. on October 27, 2009, 10:23:20 AM
Thanks to Glynn W for sending me scans of the old plans for the Bottlehead Straight 8. This design is owned by Bottlehead Corp., and we are granting you permission to build one copy for your own use. Anyone caught trying to sell speakers built from these plans for commercial gain should first be measured by a tailor to see what size lawsuit they wear.

http://www.bottlehead.com/straight%208/Straight8.pdf (http://www.bottlehead.com/straight%208/Straight8.pdf)

mid woofers are MCM 55-1870
tweeters were MCM 53-325 which are no longer available.

A search through the archives will show some alternatives. One good choice is a Selenium ST324 slot loaded horn tweeter. It requires a 4.25" mounting hole. PJ has designed a crossover for that tweeter in the Climax design (use the woofer part of the version 3.0 Straight 8 crossover for the woofers). With this tweeter I dubbed the version the P8, because it works well for PA. It will handle a ton of power, we have run them with 150W amps. Though I didn't do it in my prototype, use PJ's recommended acoustical treatment from the Climax article around the tweeter.

Glynn W has some notes about his implementation of the ST324:

Unless the laws of physics change, this should be my last post about searching for a suitable crossover to exchange a Selenium ST-324 tweeter for the stock tweeter and crossover. The woofers are still using version 3.0 of the Straight 8 crossover. Initially I installed the crossover as outlined for the Climax speaker in the community section, adding an adjustable L-pad to cut the tweeter volume a bit. After deciding I liked the sound of a .56 uF capacitor (I could not find a .62 uF as called for in the Climax crossover) I removed the adjustable L-pad and found the sound clearer, but the tweeter was still too loud for my tastes. Using the formula for driver attenuation found here - http://www.diyaudioandvideo.com/Calculator/LPad/ - I purchased a slew of Mills 12W resistors and began listening. It should go without saying that I don
Title: Re: The ART Array seems to be a cousin
Post by: AudioFred on October 28, 2009, 09:05:00 AM
I have been thinking about building the ART Array (http://fredt300b.smugmug.com/gallery/2046580/1/105115855#106644141_6xpLK-A-LB) as a Winter Project. I was surprised to see how similar the Straight 8 and the ART seems to be. I am wondering if the Climax crossover might work in the ART?

The Climax crossover won't work. This thread is about the Bottlehead Straight 8, and I don't want to hijack it, so here's the link to a thread about the Art Array with an updated crossover designed by Pete Schumacher:
http://techtalk.parts-express.com/showthread.php?t=209376

And here's the link to a recent thread with a parts list. The parts "kit" is available from PE for about $285, which means you can build a pair for about $400 total. http://audioroundtable.com/forum/index.php?t=msg&th=12188&start=0&
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: Mudhiker on May 06, 2010, 04:48:19 PM
If I use my Straight 8's on my desk, should I flip them upside down so that the tweeters are still sorta at ear-level?  Otherwise they'd be up by the ceiling which would be bad I'm guessing.
Title: Re: Straight 8 - the only Bottlehead speaker kit
Post by: Grainger49 on May 07, 2010, 12:45:12 AM
No, absolutely not!  Turn them sideways with the tweeters in the center.

(What? Still no tongue-in-cheek smiley face)
Title: Re: Straight 8 - speaker grills??
Post by: Mudhiker on October 09, 2010, 09:16:30 AM
I want to bring my Straight 8's out of storage but I have a little dog now, and sometimes he scratches things.  Has anyone used the speaker grills from Parts Express?  I'm specifically looking a the 5.25" 2-piece one.  They aren't cheap, so I'd probably just do the lower 4 on each speaker at first, if they fit.  Or if someone has a solution from another source...

Thanks

Isaac Gorton
Richland, WA
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: robertod on October 13, 2020, 07:11:27 AM
tried link to straight 8, page not found.  would like to update my straight 8's.  Is page available?
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: morris_fl on January 04, 2023, 05:56:33 AM
i have scans of the original plans that i made of my Straight 8s if anyone at Bottlehead
would like them for the forum.  (Still have my pair and they still sound great) :)
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: 2wo on January 04, 2023, 05:26:35 PM
I have used 3/8 hardware cloth (chicken wire) mounted with some adhesive backed Velcro dots so it doesn't buzz. I sprayed it black to match the speakers I used it on. I have cats, for some reason they never bother my 8's, just like to sit on top...John
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: Ken on January 07, 2023, 01:06:22 PM
I have the complete set of 16 mid-drivers, 10" sub drivers and tweeters, all new in the box if anyone is interested.  Ordered, received and never built, for reasons that involve a long, sad story.

Located Vancouver Island, Canada.
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: Paul Birkeland on January 07, 2023, 03:37:33 PM
I would purchase those parts from you if you ever find yourself across the border!  I ran into my pair some years ago, and someone had hacked up the cabinets pretty badly to add some variety of ribbon tweeter or another. 
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: Ken on January 07, 2023, 04:09:12 PM
I would purchase those parts from you if you ever find yourself across the border!  I ran into my pair some years ago, and someone had hacked up the cabinets pretty badly to add some variety of ribbon tweeter or another.

I"m never going to use these and build the speakers.  Let me know your town and zip so I can figure out the shipping cost.  If it's not too high, I will "sell" the components to you for the cost of shipping.
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: Doc B. on January 07, 2023, 06:35:55 PM
The Straight 8 didn't use 10" sub drivers. Presumably those were intended for separate enclosures. The Superwhamodynes that preceded the S8s by a couple years used some inexpensive 10" drivers in bandpass subwoofer enclosures. Very, very different design. Regarding the substitution of ribbons for the original metal dome tweeters in the S8, I wouldn't necessarily have considered that a bad thing if the tweeters were good ones and the cabinets hadn't been hacked. One of my pairs of S8s had ribbon tweeters. Maybe Aurum Cantus G2si? Recall that I modded my cabs to fit them with a little careful router work. Another pair (my last, IIRC) had the selenium ST324, which may have been the best blend of all with those MCM 5 inchers.

You guys asking for links to 20+ year old projects do make me chuckle a bit. I can't even remember what I had for dinner last night, let alone where some of those ancient files might be. Some of that stuff may have gone by the wayside when we switched servers and rebuilt the site about 10 years ago. What's left can be found below - possibly with many dead links. At some point someone sent me copies of the original printed S8 cabinet plans, but I'm afraid I haven't a clue where they ended up. Kind of a moot point - pretty sure none of the drivers for these old designs are made anymore.

https://archives.bottlehead.com/community/index.html (https://archives.bottlehead.com/community/index.html)
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: Paul Birkeland on January 07, 2023, 07:28:46 PM
I"m never going to use these and build the speakers.  Let me know your town and zip so I can figure out the shipping cost.  If it's not too high, I will "sell" the components to you for the cost of shipping.
I definitely wouldn't ship those, especially if you have the aluminum MCM woofers that Doc sprayed.  If one gets damaged in shipping, a replacement can't be recoated.  Feel free to drop me an e-mail at pb(at)bottlehead(dot)com and possibly we can figure out a time and place to meet closer to you.
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: Ken on January 08, 2023, 07:12:50 AM
Ah ha!  Superwhamodynes, of course.  Far back in the "good old days".  I stand corrected.

I seldom travel to the mainland these days but if/when I'm planning a trip, I will let you know and perhaps we can arrange a meeting somewhere near Bellingham or Blaine.
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: Doc B. on January 08, 2023, 07:46:44 AM
Quote
the aluminum MCM woofers that Doc sprayed

At some point Lord Adhesives stopped promoting that BL-100 stuff as a speaker cone and surround coating and started marketing it as a liquid (bodily fluid) resistant coating for bedsheets and gowns in hospitals. I can't even fathom how that sticky rubber stuff would feel sprayed on your hospital gown. Gross. Looks like they still make it. PJ talked them out of a pint or quart that I used for a couple years before it finally got too thick to use. I recall a gallon was very expensive and the shelf life was only 6 months.

https://www.lord.com/products-and-solutions/specialty-chemicals/aqualast-bl-100-butyl-elastomer-emulsion (https://www.lord.com/products-and-solutions/specialty-chemicals/aqualast-bl-100-butyl-elastomer-emulsion)

https://www.adhesivesmag.com/articles/86502-butyl-emulsions-offer-new-options-adhesives-formulators (https://www.adhesivesmag.com/articles/86502-butyl-emulsions-offer-new-options-adhesives-formulators)

RE Superwhamodynes vs. Straight 8s - same tweeter, different 5" drivers. The Superwhamo drivers were very high Q and I put 4 of them them in a box with a big triangular "vent" hole. More or less an open baffle. They only went down to around 110Hz IIRC. They were not coated. The 10" woofers used in the Superwhamos were inexpensive and worked pretty well in a band pass box that went from 110 down to maybe 45Hz? Can't recall exactly. Should say in the archived article.

Not too long after I made those one of the new product guys at MCM and I had a talk and a while later they came out with a 5" driver with a different aluminum cone and a much bigger magnet that had a lower Q and a resonance around 55Hz IIRC. That is the 55-1870. That is what was used in the Straight 8s, in a vented box with real tubular vents and 8 of the drivers per side. Those S8 5" drivers and the tweeters were all coated on the front with thinned BL100 using an airbrush. The woofer frames were coated with a silica loaded latex paint for a while (very messy) and later they were damped with some super trick rubber backed aluminum tape that PJ suggested. I recall having to buy a $$$ case of that tape as the minimum order.
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: Tim G. on January 09, 2023, 03:02:53 PM
Being a big fan of the S8’s I have to post this link, it appears the drivers are still available:

https://www.newark.com/mcm-audio-select/55-1870/woofer-5-aluminium-cone/dp/39C2182  (https://www.newark.com/mcm-audio-select/55-1870/woofer-5-aluminium-cone/dp/39C2182)

And I seem to recall the last version of the crossover eliminated the need for the coating on those drivers?  I’m running mine with a ribbon tweeter and they still sound great!
Title: Re: Straight 8 - the original Bottlehead speaker kit
Post by: Doc B. on January 18, 2023, 05:14:18 AM
Well whaddya know. Good find.