AudioCircle
Audio/Video Gear and Systems => Open Baffle Speakers => Topic started by: Æ on 9 Oct 2011, 05:24 am
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John Busch has been building them for quite a while. I had the opportunity to personally audition them at one of our NorCal DIY group get togethers. You can read about it and see the prototype at: http://www.positive-feedback.com/Issue31/lonestar2.htm (http://www.positive-feedback.com/Issue31/lonestar2.htm)
Scroll down a bit and look for "The John Busch Room"
Here is a pic of the finished project.
(http://ncdiyaudio.claub.net/image/obj229geo230pg12p13.png)
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Interesting rooms, and gear.
Did John Busch publish his diy plans for these small open baffle, especially the x-over schematics?
That might be a nice project for next year.
Lyndon :thumb:
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Interesting rooms, and gear.
Did John Busch publish his diy plans for these small open baffle, especially the x-over schematics?
That might be a nice project for next year.
Lyndon :thumb:
From what little I know, yes. He has displayed others too. Take a look at this, http://ncdiyaudio.claub.net/Meet-Spring2010.html (http://ncdiyaudio.claub.net/Meet-Spring2010.html) scroll down and look at project #14, a brief description is included with three pics. While you are at it, take a look at #13. Tell me if you know who/what those are?
Pic of the backside, from our DIY in 2009.
(http://www.audiocircle.com/image.php?id=52242)
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Interesting rooms, and gear.
Did John Busch publish his diy plans for these small open baffle, especially the x-over schematics?
It's all in the Manzanita thread: http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project.html (http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project.html)
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Thanks, Rudolf. All I got from AE's references were more photos. I did see the the manzanita reference when I did a search on Busch.
Lyndon
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LOL. I wondered what the speaker would be and there they are, the little Manzies. :thumb:
They are indeed very good. And there is a new version with a 3" fullrange as the tweeter.
The Peerless woofer is the heart of the system, it's a great driver. These do need a good bit of power, but that's the trade off for good bass out of a small open baffle speaker.
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Thanks, Rudolf. All I got from AE's references were more photos. I did see the the manzanita reference when I did a search on Busch.
Lyndon
I only listened to them, never inquired much about them. I had brief conversations with John Busch at the get togethers but never beyond that. Like most bipoles/dipoles his open baffle loudspeakers absolutely need to be pulled out away from the wall at least five feet, maybe even more to sound optimally. That is why I was never particularly interested in building a pair. I just don't have the space, large enough room for listening to them. But they really did sound good, very good.
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No problem, AE.
But the size of the room also stopped me. I would still like to hear them.
I keep thinking I would like to build the Metronome, or a version of the Fonken.
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No problem, AE.
But the size of the room also stopped me. I would still like to hear them.
I keep thinking I would like to build the Metronome, or a version of the Fonken.
We had a pair of "Metronomes" displayed at one of out DIY get togethers too.
http://ncdiyaudio.claub.net/Meet-Fall07.html (http://ncdiyaudio.claub.net/Meet-Fall07.html)
(http://ncdiyaudio.claub.net/image/obj475geo477pg11p13.png)
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Hello All...
Nice to see Bill's Metronomes again! So well done. Great build and sonics!
AE, thanks for the positive comments on the Manzanita. They continue to evolve and now I use a Vifa 3.5 inch as the HF driver. $12 instead of the $180 for the Scan Speak D3800. I am now in Texas and because of that was unable to attend the latest NC DIY.
Miss the group. Great folks.
I have been super busy during the last year or so, but now getting more free time. Working on an update post on the current Manzanita configuration. Think on balance, the current system is the best overall and at the lowest build cost to date.
So, stay tuned.
John
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Keep us up to date, John! With that price reduction on the HF driver, I may HAVE to build a set.
Lyndon
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Hello all.
In response to Lyndon's request to pass along more info about the current Manzanita, I have been posting over on the original DIY multi-way speaker thread "Fast, Fun, Inexpensive OB Project originally started by Pano 4 years ago. Wow, 4 years!!
Anyway, you can go there to review the latest. If members here would like me to also copy this link with all the Info over at DIY, would be happy to do so. Just let me know.
John
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If members here would like me to also copy this link with all the Info over at DIY, would be happy to do so. Just let me know.
Yes, by all means, please do so.
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AE
There have been several recent posts on the updated Manzanita over at the DIY Post. I thought about trying to cut and paste and re-post here, but there is just too much to do it in a practical way. So think it would be best to provide the link and keep things as comprehensive as possible.
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project.html
You can of course cut and paste elements you find interesting back here to help keep this thread going.
John
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The cost of the Manzanita, even with it's simplicity continues to increase, so I have been working on a new "Ultra" low cost OB two way of a similar size, and, hopefully performance. The "Ultra" uses a $26 woofer and the current and or sister Vifa FR for the high end. My goal is to get back to an under $100 OB with over all performance equal to the Manzanita. Have produced a couple of mock up versions and the project is good enough to cut some wood.
Will post the project here as it evolves.
:D
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Thanks, John. I had the privilege of hearing some of your designs at this years LSAF. The SQ convinced me that OB is the way to go for my next project. I look forward to the new design.
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Hello All
Here is the parts list for my most recent effort. I have completed the card board prototype stage and have started to build the first pair with real wood. I was trying to stay around $100 material cost each, but with inflation being what it is, I am at about $130.00 each including everything but the hand tools needed to build these. Most of the cost increases lately are coming from the Woofer and large inductor.
This OB is basically a continuation of the original Manzanita theme, but in a floor standing version with minimal fabrication requirements and lowest possible cost. It is, in some ways better than the Manzanita, but much larger. I should complete the baffles this week and will post pictures as I go. One advantage this design has is that it is less sensitive to rear wall distance than the Manzanita and performs quite nicely at 30" and even less depending on the room.
You may want to wait to purchase parts until I have completed the final build. Just wanted to get this out to show I am moving forward. A bit more to follow later today.
Economical Two Way Single Woofer – Floor Standing Open Baffle Speaker Project Parts List
2 Each, ¾” X 24” X 48” Birch or Pine plywood panels. Home Depot
2 Each, ¾” X 6” X 96” Pine boards (Ripped in half) Home Depot
3 Each, 2” X 2” X 96” Pine studs (Ripped in half) Home Depot
1 Each, ¾” X 12” X 48” Pine board Home Depot
2 Each, 15” GRS Woofers. (PE 292-415) Parts Express
2 Each, 3-1/2” Vifa Mid-tweeters TC9FD18-08 (PE 264-1062) Parts Express
2 Each, Iron core inductors, 16 Mh Erse 16 ga. (PE 266-960) Parts Express
2 Each, Resistor, 10 Watt audio grade, 4.7 ohm (PE 004-4.7) Parts Express
2 Each, Resistors, 10 Watt audio grade, 8 ohm (PE 004-8) Parts Express
2 Each, Metal film capacitors, 6.2 MFD (PE 027-236) Parts Express
2 Each, Air core inductors, 2.0 Mh, 18 ga. (PE 266-834) Parts Express
50 Each, Sheet rock screws, 1-5/8” (no. 6) & 26 each cable ties 8”Home Depot
1 Each, Elmer’s wood glue, 6 Oz.? Home Depot
1 Each, ¼” X 24” X 24” Pine plywood panel (No router required) Home Depot
Tools:
Small electric or battery operated power drill, drill bit (3/32”- 1/8”) & Phillips bit.
“C” or standard wood clamps, 3” span or larger, 2-4 each.
Saber saw, electric or battery operated with suitable (fine cut) blade for plywood.
Router with ½” – 1” flush trim bit.
Layout tools including “T” square, tape measure, pencil and makeshift layout compass fabricated from light weight (cereal box or equal) cardboard.
Soldering iron, solder & hook-up wire (18 ga. Or larger)
Wire cutter – Stripper
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One of the main considerations for this design (was - is) minimal fabrication cost and effort. Keeping the woodworking at an absolute minimum. To meet this goal, I based the project around a standard 24" X 48" X 3/4" plywood sheet. This item is available from Home Depot or Loews. Both usually keep Pine and Birch pre cut to this size in stock for small home projects. There is one good side that will accept stain and or paint with minimal sanding prep. The advantage of getting this pre-cut plywood is that it is easy to transport in most cars, low cost and you do not require a table or power saw. This is important for a lot of potential builders.
As per the previous post, only two very common power tools are required, a saber saw and power drill. For a cleaner look, and some improvement in performance, add a router.
The wings can be inexpensive 6" X 48" X 3/4" pine boards. Sometimes you can find this length in stock, but 96" long is always available. Both Home Depot and Loews will rip the 96" in half for a nominal or no charge. Or you can upgrade to white pine or the super expensive (but gorgeous) New Zealand knot free pine. If you take some time and care selecting your boards, you can usually find a nice pair of standard pine boards for the wings.
I will post some dimensional layout drawings soon. This will help show how the baffle comes together and help clarify the following general construction comments.
A router is a great tool if you have one. If not, you can still build the project. The router is used to allow for the flush mounting of the woofer and to provide a large rear countersink behind the Vifa to improve rear radiation. If you do not have a router, you can use a power saber saw to make the woofer cut out and front mount it. There is an added diffraction penalty, but not enough to seriously detract from the over all system performance.
For the Vifa (again assuming no router) we cut a 6" diameter cut out on the main baffle board . Then you need a small sheet of 1/4" X 24" X 24" pine plywood to fabricate a Vifa baffle plate. The 1/4" ply sheet is also available from Home Depot or Loews as a standard item. ($3.00 I think?) You then do a standard cut out for the Vifa on the 1/4" ply (as shown on the forthcoming layout drawings). The 1/4" ply baffle plate is glued and or screwed to the front of the main baffle with the Vifa centered over the 6" cut out. The 1/4" plywood sheet will have to be reduced in size of course, but this is quite easy with a saber saw. The Vifa baffle plate is not very elegant, but works just fine. The edges of the 1/4" plywood can be easily rounded with course sand paper and finished to suit prior to mounting on the main baffle. The Vifa baffle plate ends up around 7" high and 8-10" wide.
That's about it for now. Again, when the layout drawings are posted the above will show what I am up to. A 2" X 2" sub frame need to be built to hold it all together. The 2" X 2" can be cut with a simple hand saw or saber saw. More on the sub frame later. Total project time is 4-6 hours depending on wood working skills and so on.
More thoughts and technical info will be posted as I complete the first demonstration pair.
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A router is a great tool if you have one. If not, you can still build the project. The router is used to allow for the flush mounting of the woofer and to provide a large rear countersink behind the Vifa to improve rear radiation. If you do not have a router, you can use a power saber saw to make the woofer cut out and front mount it. There is an added diffraction penalty, but not enough to seriously detract from the over all system performance.
My router was stolen, but they did leave my Jasper Jig. I have the privilege of using a large cabinet shop but it was recently broken into and everything of value that could be carried out quickly was stolen, including a few of my own personal power tools. Bummer. They didn't steal the table saws because those are too big, heavy to easily move, too big to carry.
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OK, I am back with more info on the New GRS 15" woofer based Low cost OB Project. Sorry for the delay, have been fighting the flu and other crud now for nearly a month!
I have decided to name this project the "Ultra" as I believe it to be a viable "Ultra Low Cost" design especially considering it's simplicity and the wide frequency band it can cover. (35-18K +/- 3 db or so).
I have completed the initial baffle and crossover fabrication and will post a few pictures shortly. The above noted frequency response is obtained with the Ultra placed between 27" and 38" from a sheet rock rear wall surface and measured on axis at about 8' from the front baffle surface. (ARTA - True RTA & Holm) The crossover assumes a 32"-34" rear wall distance and offers excellent tonal balance. As best I can measure a typical "in room" net mid band efficiency is 83-85 DBW and is a bit dependent on rear wall distance. I bit higher efficiency with less distance, but at a cost of bass extension. And, conversely, as the distance from the rear wall increases you get a bit lower efficiency but with better bass extension. With out the rear wall reflection - return, (measured out doors away from rear reflective surface, the intrinsic efficiency is about 82 dbw).
You can drive the speaker to usable levels with 10 - 20 wpc, however 35 - 100 wpc allows the system to reach it's potential. So a PE Dayton chip amp (300-383) or the very low cost Sherwood stereo receiver 252-125 will do quite nicely and both are available for under $ 100.00 each delivered. The Sherwood RX-4105 is surprisingly good. Will it challenge my class A or SET tube units, no. But for $100 driving the Ultra it works amazingly well. It clips at around 110 WPC in to an 8 ohm load. BTW, the power handling of the Ultra is about 100 watts, so the Sherwood or similar mate up well. Assuming 84 db per watt as a basis for the Ultra, a Sherwood - Ultra combo can easily reach the mid to upper 90 db output level at a 8-12' listening distance. So for just over $360 and some sweat equity you can have a very capable system. Just add a CD or other line level source. Heck, FM of the Sherwood can be quite enjoyable!
As for the final crossover, I am still auditioning the ultra with various amplifier and CD player sources trying to reach a balance the works well overall. Most of this is balancing the high pass crossover point, trap and pad. FYI, I see Zaph has measured the Vifa and found it to have a very linear on axis frequency response. The Vifa for the price is a remarkable driver!
Pics and more info to follow!
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OK, trying to post a few pictures of the Ultra to help fill out the project. The views are self explainatory.
(http://www.audiocircle.com/image.php?id=54849)
(http://www.audiocircle.com/image.php?id=54850)
(http://www.audiocircle.com/image.php?id=54851)
(http://www.audiocircle.com/image.php?id=54852)
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Thanks for the photos. Can you review the crossover for us? It looks pretty simple.
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OK, trying to post a few pictures of the Ultra to help fill out the project. The views are self explanatory.
Any reason why the tweeter cannot be closer to the woofer?
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The driver locations on the baffle are based on a combination of factors. The tweeter is offset from the center line to help with imaging, diffraction smoothing and proper OB loading. The position on the baffle provides part of the low end roll off slope and frequency knee. Also, I set it 38" off the floor to be on axis for a seated listener. The woofer location is just off center vertically to help minimise rear standing waves, maximise OB loading (lowest possible F= for the baffle - wing combo) and high enough off the floor to minimise floor bounce. One could move the woofer upward closer to the Vifa. You would want the final woofer position to remain off center vertically, above center if it is moved closer to the Vifa. There may be some modification required to the crossover if it is moved. The crossover is optimized for the current driver vertical separations. Hope this all helps.
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The woofer location is just off center vertically to help minimise rear standing waves, ... and high enough off the floor to minimise floor bounce. One could move the woofer upward closer to the Vifa.
Funny. Is moving the woofer to the floor no longer the best way to minimise floor bounce? Was Allison wrong?
Rudolf
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There are many aspects to any given design. With the ultra's design, if the woofer were mounted as low on the baffle as possible, the woofer - tweeter vertical separation would become a major issue. Maintaining the Vifa at around 38" above the floor for me IS very important to the overall performance and power response of the system. There is a limit to crossover correction capability relative to vertical separation of the two drivers. Somewhere around 15" of center to center separation seems to be the limit. Otherwise major lobing issures begin to degrade the SQ. The accoustic crossover point is centered around 550 Hz, but the up woofer contribution reaches over 1 KHz, although it is down about 18 DB at that point. The Vifa is contributing down to about 175 Hz. (Down about 24 db at that point in overall power response).
Larger separation was not possible when maintaining a simple crossover topology - cost. So the best trade off was to mount the woofer up higher. With the woofer contributing well into the mid range, mounting it higher gets it's mid range output closer to the overall speaker axis. And with an OB woofer that is playing into the mid range, one has to deal with rear radiation issues including absorption than can occur with residential carpeted surfaces, front also.
Bottom line is the woofer is up where it is for a number of reasons. Mr. Allison is just fine when operating in a traditional monpole environment..
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There are many aspects to any given design. With the ultra's design, if the woofer were mounted as low on the baffle as possible, the woofer - tweeter vertical separation would become a major issue. Maintaining the Vifa at around 38" above the floor for me IS very important to the overall performance and power response of the system. There is a limit to crossover correction capability relative to vertical separation of the two drivers. Somewhere around 15" of center to center separation seems to be the limit. Otherwise major lobing issures begin to degrade the SQ. The accoustic crossover point is centered around 550 Hz, but the up woofer contribution reaches over 1 KHz, although it is down about 18 DB at that point. The Vifa is contributing down to about 175 Hz. (Down about 24 db at that point in overall power response).
Larger separation was not possible when maintaining a simple crossover topology - cost. So the best trade off was to mount the woofer up higher. With the woofer contributing well into the mid range, mounting it higher gets it's mid range output closer to the overall speaker axis. And with an OB woofer that is playing into the mid range, one has to deal with rear radiation issues including absorption than can occur with residential carpeted surfaces, front also.
Bottom line is the woofer is up where it is for a number of reasons. Mr. Allison is just fine when operating in a traditional monpole environment..
I still don't like the tweeter separated so far from the woofer.
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At a crossover frequency of 550 Hz, the driver spacing looks manageable. While one might prefer closer, the impact of other factors would probably supercede that of the drivers being as close as possible.
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You can move the woofer closer by around 2". Any more you will over lap into the Vifa counter bore on the rear of the baffle. You can barely see the dotted layout circle surounding the Vifa on the pic I posted a couple of days ago. The rear counterbore is 7" diameter IIRC. Not as much un unused baffle space as one would think!
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By introducing the GRS woofer the 'Manzanita' is approaching the normal 'MJK' type of OB speaker: http://www.quarter-wave.com/OBs/OB_Design.pdf
No more relying of 'Phantom' sounds in the deep hollow between bass and treble, and frankly I don't think the second version was really on target.
For bass quality I think it is a step down from the Peerless unit, for quantity it might be OK but you can't really approach any bass heaven with the GRS, 90 dB will not be attained at 40 Hz for instance in X-max limits.
No doubt the Vifa unit is a real find and it is also about 5 dB more efficient than the single GRS so two bass speakers might be more appropiate for matching.
I have been a bit famous for chasing MJK's Alpha15 recommendation for quality OBs. Judging from email and other support I may be right, So it is the question of the GRS sound quality. Not compared to quality units it will be OK but I certainly doubt that the real high quality will be there. For very little money anyway you certainly will be enjoying uncomparable OB sound.
/Erling
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Interesting comments Scorpion. What, or should I ask which "second version" are you refering to?
As for comparing the Peerless to the GRS, today the Peerless is over 3 times the price and is still a bargain! However, the GRS is every bit the sleeper-performer for the money as are the Peerless or the Vifa. I think once a few of the Ultra's are built, most builders will be more than satisfied with the performance it provides, especially when one factors in the simplicity & cost. As for "channelling MJK" with the Ultra, that was not what is intended. When working up a viable low cost, bang for the buck OB capable of extened bass response, you are limited to large diameter, small motor woofers. Simply a cost reality. And the GRS can deliver around 93.5 db (96.5 FOR A STEREO PAIR) at 40 Hz in a typical 1/2 space residential setting. This is assuming 0.4 meter path difference, 860 sq cm cone area and a usable PP xmax of 9 MM. The 9 mm value is based on listening and test measurements. Not bad for $130 speaker! The Manzanita will play a couple of db louder at 40 Hz. It is capable of 18 mm p-p, but the 12" Peerless has less cone area on a way smaller baffle.
For most users and most music, a pair of GRS-15's will be very usable. And, you must remember the Vifa is pretty much reached it's clean peak output in the around 95 db or so on the lower end of it's operating range.
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John,
Quick question. I did a quick check on the BOM and it appears PE 266-960 is a 20mH inductor, not 16mH. Can you clarify?
Also, can you connect 18ga inductors in series to arrive at the same inductance? Would the DCR matter much in this case? Maybe cheaper this way.
Thanks,
Duc
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Thanks for noticing. Typo on my part. 20 Mh is correct. You can use an 18 Ga. if you wish. You may have to adjust the Vifa pad resistor to bring the Vifa output down to match. Difficult to predict exactly how much. I need to experiment a bit to see if it is enough to mater.
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I won't argue details about your speaker because I do think it very good value for money.
The second version I am referring to is with Peerless and Vifa and this I think had too far crossover values to really be able to sound anywhere what it really could have been with better crossover values !
Now with nothing presented, only 550 Hz hinted, most is in the air. :)
/Erling
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Yes, the Manzanita Vifa version crossover values do look strange. However, after hundreds of hours of listening, measurements and god knows how many configurations, the current values are what work. Very flat on axis and power response. A lot of reasons for this. Do not have the time today to fully discuss. One reason I demo my creations at DIY and LSAF and similar venues is to get as many opinions as possible. Gut check if you will. Good & bad. Learn the most from the bad, what little there has been.
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Now this is OK !
If you believe my honest will I won't argue yours !
It works and that's it ! :)
/Erling
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:banghead:
Trying to upload a couple of Ultra dimensional pencil drawings but not having much luck. Have reduced them to under 50K so size should not be the issue. Any suggestion?
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John emailed me the sketch, let's see if I can upload it here.
(http://www.audiocircle.com/image.php?id=55025)
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Did I miss the schematic for the cross over? I see the BOM but not the layout for the Ultra.
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I am working on the final crossover diagram with notes. I hope to post by this weekend. John
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OK, here is my crude pencil sketch schematic for the Ultra OB. I will try to talk Pano into posting something way more professional looking after he returns from his swamp trip!!
The configuration shown has been listened to extensively with a wide variety of music and amplifiers. The amps included a 5 wpc KT88 SET, 15 wpc KT88 SEP, 30 wpc class A PP EL34, 30 wpc Virtue II chip, 38 wpc PE Dayton chip, Rat Shack 75 wpc receiver, Sherwood 110 wpc receiver and 200 wpc Musical Fidelity A308. The stated out put power values are what I have measured into a static 8 ohm load and do not necessarily jive with advertised ratings. After all of that, I arrived at what you see. For most of the above, in a 20' X 25' x 8.5' room with carpet and furniture, the tonal balance is fairly neutral except with the PP transistor receivers. The receivers are a bit dull and can benefit from a lower pad resistor, say 4.5 to 5.0 ohms. One of the fun parts of this design is you can play all you want! Some may want to experiment with attaching felt strips in various places, like on the inside of the wings adjacent to the Vifa and or the GRS. Or on the baffle face.
This speaker has excellent and very full lower midrange. Clarinets and such have a lot of body while maintaining surprising clarity. Some may feel TOO much body. To adjust this, a reduction in the high pass capacitor to around 5 MFD or so may be what you may find preferable. I have made some previous comments concerning positioning distance from the rear wall. I prefer about 36". Some may find a bit of toe in toward the listener will have a positive effect imaging.
Make very sure your baffle structure is tight. If you have a signal generator run it up and down until you eliminate all rattles. Seems that the 45-70 Hz region is most prone to producing unwanted baffle noise. Those with out a sig gen can use a test CD (warble tones and the like).
I will be interested in hearing back from those who build this project. I truly feel most will be surprised at how good this speaker is with in it's out put and efficiency limits. It is very revealing of amplifier and source quality. What I found interesting during the audition process is that the Ultra easily demonstrated amplifier quality differences. Very uncommon for a speaker of this simplicity and low cost.
Good luck and ENJOY!!
(http://www.audiocircle.com/image.php?id=55178)
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And this is a MJK model simu with correct crossover values, not counting with the BSC-circuit and not corrected for the Vifas higer sensitivity:
(http://img52.imageshack.us/img52/6631/grsvifa.jpg)
/Erling
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Scorpion....
Thanks for running the simulation! Pretty ugly isn't it!!! But the world of the OB can be surprising....
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To me you are wasting the Vifas capacity now and I would rather have that unit play than the probably 'sloppy' woofers like the high Qts Alpha15s. I could understand the coupling between the Peerless and the dome tweeter in the MK I because the tweeter could not be crossed lower. Now with other woofers and another fullranger I think the MJK type of construction is more rewarding also soundwise.
/Erling
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I will see if I can put together some acoustic measurements from Arta & True RTA and post them. Needless to say the spectrum at the listening position is radically different from the simulation.
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If I have done this correctly here is a snap of the Ultra Impedence and phase characteristics via WT3.
(http://www.audiocircle.com/image.php?id=55293)
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Here is a marginal resolution ARTA measurement taken on tweeter axis at approximately 8'.
I will work on a higher resolution snap tonight. There is a bit of noise on both ends of the spectrum and anything above about 16K is not representive, same thing below 40 Hz. You can see some baffle face reflection issues around and just above 2K. And you see some wall reflection - room issues right at 50 Hz as well as some baffle buzz suck out at 60 Hz. Will work on eliminating the Baffle noise before I take any more data. But all and all flater over all than it has a right to be. Will work on some Holm measurements next.
(http://www.audiocircle.com/image.php?id=55298)
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Here is the True Audio sweep. 1/3rd octave is what my version does and makes things look a bit better than they usually are. But, I have found the rounded True Audio frequency curves tend to jive with what one hears in the listening chair. True with mono or dipole sources.
Will be interested in what others measure in various venues.
Working on a couple of holm frequency and phase plots.
(http://www.audiocircle.com/image.php?id=55305)
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Thanks for posting actual FR plots. The only thing I enjoy more than measurements matching listening impressions is when reality (i.e. measurements) disproves a bad simulation.
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More observations.
Some may prefer the running the Vifa in reverse polarity. This does provide a flatter on axis response. However, it is a bit hotter to my ears on the upper end so for some listeners a little more pad may be in order, say 6.2 ohms or so. There is some improvement in the area of midrange detail, but the mid bass seems to fatten up just a bit. Need to experiment with Vifa polarity VS. rear wall distance and report back on that.
BTW, Jarome, thanks for sending your sim data via PM.
Each polarity has it's own sonic signature. Both sound great which, givin the simulation differences is quite surprising. It will be interesting to get feed back as to which polarity is most popular.
Using the Holm measurements you can really see quite a difference. Will post some snaps later as I have the time.
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Thanks for posting actual FR plots. The only thing I enjoy more than measurements matching listening impressions is when reality (i.e. measurements) disproves a bad simulation.
The ultimate is when a simulation matches the measurement and the listening impressions are favorable.
(http://www.audiocircle.com/image.php?id=55329)
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Hmmm, very interesting. How did you arrive at a different simulation than scorpion?
The ultimate is when a simulation matches the measurement and the listening impressions are favorable.
(http://www.audiocircle.com/image.php?id=55329)
(http://img52.imageshack.us/img52/6631/grsvifa.jpg)
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Martin. Thanks very much for the simulation. It's looks very close to the measured responses. What do you think accounts for the 20dB rise in the bass and mid bass your simulation? Wall distance?
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Hmmm, very interesting. How did you arrive at a different simulation than scorpion?
I modeled the actual crossover layout as shown in the sketch and reset the SPL plot scale to match the measurement plot scale. The measurement plot scale and the smoothing applied compresses the peaks and dips so the response looks much flatter, Erling's plot looks much worse because of the scale and lack of smoothing. I set up the simulation to match John's description of his measurements.
I have reverse engineered hundreds (if not thousands) of speaker designs over the past 25 years and have usually been able to get my simulations to match the measurements if enough information is provided. You learn a lot by reverse engineering a speaker design.
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What do you think accounts for the 20dB rise in the bass and mid bass your simulation?
The 20 dB difference between the bass and the mid bass is a result of driver selection and the crossover, nothing to do with the room. It appears to be inherent in the design. I have found that I like my OB's performance better if I boost the bass a couple of dBs but not as much as shown in the measurement plots.
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Thanks Martin. I 'm curios because your sim is very close to the measured results, except for the extra ~10dB simulated in the 40-50Hz region. John's measurements show about 10dB of boost there, yours about 20dB. John puts this down to noise, but I'm not sure it's all measurement noise, I think a lot of it is real content. Measuring bass in a room isn't easy.
I've been helping John with measurement hardware and software and have seen many of these come across my desk. It's nice to see the sim so close thru the midrange and above, just wonder what new info would useful to get sims and measurements closer in the bass.
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I 'm curios because your sim is very close to the measured results, except for the extra ~10dB simulated in the 40-50Hz region. John's measurements show about 10dB of boost there, yours about 20dB. John puts this down to noise, but I'm not sure it's all measurement noise, I think a lot of it is real content. Measuring bass in a room isn't easy.
If I try and read the plot values at 50 Hz and 300 Hz and calculate the deltas I get the following.
ARTA = 17 dB difference
True RTA = 14 dB difference
MathCad = 18 dB difference
Measuring low frequencies in a room is difficult, but I have found that the problems start below 40 Hz. I have always had good results above 40 Hz if I am very careful.
One source of error in the simulations is created by my using manufacturer's data for the T/S parameters (we know that is a big assumption). If I were using measured values, I believe the simulation would be even closer to the measurements. If I were doing the design myself I would also use measured values for the crossover components.
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Truer words have not been spoken.
The ultimate is when a simulation matches the measurement and the listening impressions are favorable.
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Thanks to Martin, Pano, Scorpion and AE for your comments and sims.
Nearly all the crossover layout decisions for the Ultra were made based on SQ. Just wanted to see where my ears would take me. Found out long ago using most of traditional monopole crossover layout theory with OB designs to be a waste of time.
As far as my measurements go, as we have come to know, getting OB in room measurements that reflect what one hears at the listening position can be problematical. What I have posted thus far is more or less typical of what I am getting at 8'-12' of distance, on tweeter axis. There does not seem to be much side wall reflection information getting to the mic at that distance.
If I move closer or father away from the baffle, things, as you would expect, can change considerably. The usual stuff, like the low end extending deeper with a more up shelf output as you move closer. Mid room tends to have a bit of a mid bass null - lumpy-ness and way back the extreme bottom end comes back up and the bass overall smooths out. Some of this is typical OB behavior and some is due to room interaction.
I think all will find the Holm measurements of interest. I am optimizing a reverse Vifa polarity version based on listening. The two polarities show very different measured behavior, but as I said before, not all that much SQ difference. I will post the reverse polarity Crossover hopefully later today.
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Hello all
Here is the Ultra Holm combo plot of Vifa in phase (showing the classic crossover frequency summation dip) and out of phase exhibiting classic phase correct flat summation band pass behavior. Looks like we have a classic 2nd order response. There are of course room behavior artifacts, as well as compromised measurement technic issues.
But... I think it shows the crossover component values to be spot on. How did we end up with what looks like 2rd or 4th order roll off symmetry on the woofer low pass with just a single inductor? Same goes for the Vifa with it's single cap high pass element.
This data was taken at 9' prox on Vifa axis at a couple of volts input. Baffles toed in about 5 deg. relative to rear wall with baffle to rear wall separation at 36".
Again, I must emphisize that both solutions sound quite nice and reveiling. In phase, overall, especially in small rooms or at listening distances under 8' sound more coherennt.
(http://www.audiocircle.com/image.php?id=55361)
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Thanks for posting that, John. Nice to see the reverse polarity plot. The circa 2.5K glitch is odd and may be a baffle artifact. What do you think?
Martin, right. Published specs. I believe that John has measured T/S parameters for the actual drivers and may be able to post them here. It's will be interesting to see what difference that makes.
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Here is the PE GRS 15 WT3 sweep taken with the driver on the baffle.
(http://www.audiocircle.com/image.php?id=55373)
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Here is the Vifa WT3 plot mounted on the Ultra baffle. No crossover with the Vifa or the previous GRS 15 post.
(http://www.audiocircle.com/image.php?id=55374)
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Some more measurements...
Here is the first of more Holm in room snaps for the Ultra. This one shows the GRS 15 on baffle at 8' on axis with a MLS Sq noise sweep (reddish brown trace) and standard log sweep. No crossover inductor. The lower end below about 100 Hz is not acurate, as in too smooth.
(http://www.audiocircle.com/image.php?id=55382)
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Here is the Vifa on Ultra baffle, no crossover. Again, the very low end is not representive of reality. Blue trace is log sweep, Redish brown is MLS Sq noise. The spikes at 450 & 1.8K are anomalous noise.
(http://www.audiocircle.com/image.php?id=55383)
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Thanks John for the graphs. It would be nice if you could repost them not gated, but maybe at 1/12th octave smoothed. The gated measurements always confuse me. :?
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Hi,
I was away with my 99 year old mother for Christmas so I didn't send any comment during that time.
Regarding Martins reverse engineered speaker and my sim. There is a close resemblance, both about 20 dB down for a hole in the response. Martin is much more near the thruth by beeing able to take into consideration both the step down resistor value and the BSC-circuit, also in step down duty for the VIFA. Martin is of course able to enter such values in his software, where he knows the entries. But that we should be thankful for. I would be extremly surprised if the new Manazanita speaker would sound any where equal, with its Phantom Sounds reliance, to a more traditionally (ie in the MJK-style) constructed OB speaker.
To me this is not taking care of the fine virtues of the surprisingly good VIFA engine. I shall not speak over the GRS woofers, I have done that once alredy and that's enough. :)
/Erling
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She's 99? Very cool! Hope she has a happy 100th. :thumb:
I would be extremly surprised if the new Manazanita speaker would sound any where equal, with its Phantom Sounds reliance, to a more traditionally (ie in the MJK-style) constructed OB speaker.
Then why does it measure so flat? John has shown several raw measurements and it's pretty darn flat. No hole, unlike the sims. Why? Is he measuring wrong, or the wrong thing?
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Thanks Pano, I hope she will last until the 28th of June this year for her 100th birthday. I think she will.
Regarding the Manzanita I will not give any more comment. I think whats given is enough. :)
/Erling
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Then why does it measure so flat? John has shown several raw measurements and it's pretty darn flat. No hole, unlike the sims. Why? Is he measuring wrong, or the wrong thing?
I thought the measurement and the sims aligned very nicely considering all of the assumptions required. The first set of measurements look very flat because the scale is so large. The original measurements and the sims seem to both show a wide 15 - 20 dB dip in the mid range. Correlation looked really good to me.
Martin
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Yes Martin, better agreement with your sim, for sure. I would be nice if John could post the T/S parameters of the actual drivers for another, better pass of simulation.
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Pano
Do you want the T/S values with the drivers mounted on the baffle or free air? T/S values or complete WT3 sweeps & info?
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I think for Martin's sims free air is needed. I don't know if he needs the impedance curves (or numbers) but I guess it couldn't hurt. The exported numbers could be zipped and posted.
Post the free air T/S and let's see what Martin says. The DCR of your coils might help, too. Thanks!
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Posts 61 and 62 contain T/S parameters for the drivers. I checked them for consistency and everything matched. Putting these values into my original sims did not change the results significantly. The dominant contributor to the dip in the middle of the SPL curves is the fundamental crossover design, not the driver T/S parameters. I don't think this set-up will sim or measure flat, but if it sounds good who cares.
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Pano & Martin
Thanks for you input. I am still tweaking negative and positive polarity crossovers. Mainly working the HF trap - pad values. Balancing what measures good with what sounds good and trying to understand crossover - accoustic relationships. Once I have taken things as far as I can, will post updated crossover(s) and measurements.
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My new Manzanita Ultra build.
Hello John and fellow diy builders. I have had the great fun of building the Manzanita Ultra's the last couple of weeks. I hooked up the speakers to my tube pre-amp and B&K ST202+ power amp yesterday night. First impressions are very good, with a very impressive bass and homogenous overall sound. Very low and clean bass notes. This is only my first listening impressions with new drivers, no proper burn-in period done. Thank you so much John for sharing this exciting and elegant design with the diy community! \Hans in Holmsund, Sweden.
(http://www.audiocircle.com/image.php?id=75525)
(http://www.audiocircle.com/image.php?id=75525)
(http://www.audiocircle.com/image.php?id=75526)
(http://www.audiocircle.com/image.php?id=75527)
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Nice looking build! Keep us posted on hoe you like the sound.
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very nice build indeed
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Here comes an update after 150+ hours with my Ultras. I'm VERY pleased with the performance of the Ultras. I've becomed addicted to the smooth and open sound and the very powerful, low octave bass. I heartily recommend building or buying these excellent speakers from John (www.manzanitaaudiosolutions.com).
\Hans in Holmsund, Sweden.
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Hans....
Thanks for sharing your opinion of the Ultra build! Know it was a lot of work to obtain the GRS in Sweden.
I fear a lot of potential builders have difficulty believing how good such a simple design and build can be. And they worry about the intrinsic low efficiency. However, if you run the numbers and measure most designs that can really play flat into the upper 20's, you will usually find one of two outcomes.
1) The enclosure is the size of a double door refrigerator, or... 2) The true efficiency is similar if not less than the Ultra. As best I can measure, the Ultra is around 84-85 dbw. And that is all the way down. No roll-off!
Provide a clean 20-40 watts per channel in a typical domestic setting.... for most music, you have more than enough output.
Funny thing about the Ultra is the tonal purity of the bass. It's all most creepy to hear true fundamentals with out the usual doubling nearly ALL speakers regardless of design produce below 50 Hz or so. That is why the Ultra low end is SO addictive... as you observered.
__________________
Commercial Website: http://www.manzanitaaudiosolutions.com/index.html
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First, thanks John Busch for posting this design.
I've been looking for some time at these two drivers to attempt an open baffle design of my own, so when I came across this thread I thought that I might gain some insight into designing an OB passive crossover.
I've always found that researching and reverse engineering on my own provides the greatest rewards in understanding. However, after spending hours with Edge and researching OB and crossovers, I have reluctantly come to the conclusion that I am not going to understand this particular crossover without help. In particular, I am completely baffled by the full-pass filter. On first look, it appears to be a 1st order bandpass filter, but I don't understand why you would want to roll off the high frequencies in this application.
So, my questions are:
1. What is the full-pass inductor and resister in parallel doing?
2. Is the full-pass capacitor and inductor in series a 1st order bandpass crossover, or is it something else entirely?
3. How are the resistor values used to calculate crossover points (i.e. sum both resister values plus the speaker impedance and Inductor DCR)?
4. Are the resisters more then just attenuating the full-range driver?
Any help would be appreciated. Regards.
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:D
Hello P-10
Thank you for your interest in the Ultra!
Will try to answer your questions in order presented.
1. This is a simple trap that compensates for the rising response of the Vifa which begins around 5Khz. Including the rear radiation, the overall rise is considerable. The trap will yield a flat on axis response in most rooms with the Ultra 30"- 50" away from a wall.
2. The large inductor does three things. It corrects for the rising response created by the open baffle and the naturally rising response of the woofer. It also help create a defacto 2nd order acoustic 700 Hz crossover point when it combines with the woofers natural upper roll off. The cap in series with the Vifa combines with the Vifa's natural low end roll off to create a second order crossover, again acoustically at 700 Hz. The calculated electrical values are god knows what. You can reverse engineer if you want to, but with both drivers radiating both directions and adding in the diffraction effects and well as the comb - roll off effects of the large open baffle, standard calculations are not of much value.
3. By ear and measurement. Yes, in the initial design I considered the intrinsic efficiency of the drivers factoring in the anticipated rear radiation. Plus series loses and driver dcr values.
4. The pad resistor is general attenuation. The trap resistor sets the amount of upper end frequency shaping. Smaller values, less shaping, larger values more. FYI, the trap inductor set the frequency at which shaping starts. Larger value, lower start frequency.
Hope this info is helpful.
Best
John
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(http://www.audiocircle.com/image.php?id=102426)
I have a pair of John's Manzanitas and once I tamed the newer Vifa's hotter upper end, they have been marvelous. I listen to a lot of live recordings from large venues and the OB with the large woof really shines with this material. So the Ultra's 15" woof is calling out to me. A build seems unavoidable at this point. And this thread needed a bump anyway......
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motosapien-how did you tame your vifas? Just curious....
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John's original Manzanita design called for a 2 mh coil with a 5 ohm across it. The latest run of these Vifa's was a bit brighter up top and needed a 2.5 mh with a 15 ohm across it. Then 5 - 6 ohm for attenuation depending on the woofer.
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Here are some shots of my Ultras to bump this thread. The fronts are finished and look pretty good but the backs are still unfinished so there aren't any shots of the rears.
Overall it's been a great project. They sound nicer than they have any right to sound for the money spent and they have a very pleasant sound signature. Great recordings shine but you won't get ear bleeds from the poorly recorded stuff in the collection.
The only issue with the build was the quality of my woodworking. The hole for the 3 1/2 inch driver was just a bit too big and there was a very slight gap between the driver and the wood. This did reduce the quality of the midrange and high frequencies but a bit of rope caulk around the gap fixed the problem.
The bass was always good but with a few gear improvements the bass is now really amazing. Tuneful, articulate and plentiful. Folks ask if the subwoofer in the room is on but it's not.
They are a bit laid back sounding with the stock crossover and it's been fun making modest changes to suit the changes in audio gear and mood. In my room I seem to like a bit more output from the high frequencies so there are a few resistors tweaked.
It's a good project.
(http://www.audiocircle.com/image.php?id=108901)
(http://www.audiocircle.com/image.php?id=108902)
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Those are handsome barry - you did good. How are you liking the base response? John's designs are somewhat unigue in that they do not require biamping. This makes life easier, particularly for the entry level builder. It also makes for a more commercially freindly product.
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Thanks Motosapien. They don't quite look that good in person but the light was hitting them just right the other day so it was time for some photos.
Bass is pretty amazing. There is a lot of it and it has real texture. Upright bass has the right tone and texture and the 15" drivers move enough air so you feel it.
There is enough bass that placing the Ultras in the room is sort of critical. The bass can be very loose if the speakers aren't in the right spot so it can take some time to get them setup correctly. Once you hit the right spot and the right toe in they'll really let you know.
Placement of the smaller Manzanitas was also pretty critical but there seemed to be a bit more wriggle room with them. One or two spots would both sound good and it was just a question of personal preference on which spot was "best".
Changing the crossover resistors will also change the bass output of the Ultras so they're easy to tweak. I still haven't quite decided which settings are "best" but have been leaning pretty close to John's specs most of the time.
The Ultras are significantly better sounding than my Manzis but my Manzis are the original version with the 1st tweeter. I suspect your Manzi build with the full range driver is up a few levels from mine. So even though I've got both speakers I can't really do a good comparison between the two builds. But based on my two builds, IMHO, the Ultras do put out more bass than the Manzis.
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I too am interested in these "Ultras". While a strong emphasis on bass and mid bass has been made in these threads I have read very little about the upper end, other than for some it may seem "too hot" and for others, not enough. Some of my experience with small, "full range" drivers, some costing several times more than the TC9FD, is that they tend to sound a bit muted above 15kHz, as if playing behind a veil or something. I enjoy this upper end sparkle on strings, cymbals, bells, chimes and the like, and even the top octaves of a piano doesn't sound right if the driver can't swing those higher frequencies.
Is the TC9FD capable? What sort of changes can be made to the XO to liven up the top end, if needed?
Last but not least this XO uses a lot of serial design, which I read (somewhere) might not be well liked by class "D" amps, which I have. Should this design be pretty amp friendly to class "D"?
Thanks in advance!
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Barry - beautiful work!
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Anybody still using these in 2018? They are intriguing.
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Mine are still here. Just feed them some power and they sound great. A 5 watt amp isn't going to do it but a 50 or 100 watt amp probably will depending on your room and personal need for volume.
John and Pano have posted updates to the stand mounted Manzanitas on the DIY site so that's worth checking out, too. It's also where you can get the latest version of the Ultra crossovers.