Pete B
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Posts posted by Pete B
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I have several 12" Rectilinear III woofers with redish cloth edges and ceramic magnets
that I'd like to sell if you are interested. Where are you located?
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What is the correct woofer for this speaker, make and model?
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I bought a used pair of Vandersteen 2 Ci s years after finishing college in order to
reverse engineer them and hopefully improve my speaker design skills:
Was not impressed with them.
I became interested in the SPICA TC-50 when they came out years ago because of the rave reviews
and linear phase design. I finally reverse engineered them years later, I'm not impressed with them:
http://baselaudiolab.com/MR-TC50-REB.html
I also reverse engineered the PSB Stratus Golds and I do like them, great design but
I never published the work other than the crossover schematic. I also helped a friend
roughly "clone" them in the late 90s - he says he's never letting them go.
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@TheFrugalAudiophile
I've always been interested in anything that can improve the listening experience and
I became interested in "time alignment" and "linear phase" designs, sometimes now
called "transient perfect" or "quasi-transient perfect".
I went to hear the Dahlquist DQ-10 and always thought that they sounded good but
never fully believed the hype about time alignment.
This is a story that should give a laugh and pertains to EPI/Genesis:
When I was in college I became a member and was reading the Audio Engineering Society (AES)
Journal. There was a lot of hype in the press and an AES paper from B&O about their
filler driver method for designing a "Linear Phase" speaker. I was lucky enough to have at least
4 HiFi stores within 15 miles of our home. One had the B&O speakers and I went there to
hear them, in those days they offered an A/B switch and could patch in any two speakers.
The young sales guy said sure I can demo the B&O speakers, here's a mid (high) priced model.
I thought the bass is not even as good as Large Advents, and they were not at all musical.
Then the kid says, do you want to hear some good speakers? I said sure, he patched in the
Genesis 2 speakers on the B side of the A/B switch and said these are half the price. I was
shocked bass significantly better than the Large Advents and a smooth, musical midrange
and top end. I said I don't want to hear anything more from the B&O s and I could listen to
these Genesis 2 s all day long. I never bought a pair, my big TL speakers were better but
suggested them to others:
https://community.classicspeakerpages.net/topic/3874-genesis-ii-rebuild-design-comments/
They are an EPI 100 in a bigger box, with a passive radiator:
http://www.humanspeakers.com/genesis/gen2.htm
I just in the last year or so added a pair of Genesis 2+ to my collection in real wood:
https://www.humanspeakers.com/genesis/gen2plus.htm
They compare very well to PSB Stratus Golds same deep bass but have about 6 dB less
max output in the bass. Much simpler design and probably a sweet spot for cost/performance.
There have been several scientific articles in the AES demonstrating that linear phase is not
important to humans in the home listening environment and this demo drove that point
home for me - B&O vs. Genesis 2.
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@TheFrugalAudiophile
I started building speakers as a very young kid and read everything I could find about them.
I read about IMF Transmission Lines (TL) and was very impressed with their bass performance.
I tinkered around with them, built some that could shake the room with deep bass, and studied
them as a senior project in college. My project advisor suggested that it should be possible to
get as good bass as a TL with a vented system (ported or passive radiator). I did not have time
to explore this but I believe that the Stratus Gold is a good example of how a vented system
can provide as good if not better performance than a TL. The formula is a big box, low port
tuning (Fb) and high port area for minimal turbulance (minimize compression) or a passive radiator.
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@TheFrugalAudiophile
It is interesting that you ask what I listen to at home. I'm a speaker collector but one of
my favorite designs is the PSB Stratus Gold. I always admired KEF 105 s and B&W 801 Matrix
series II which I'll probably add to my collection someday. This is the B&W 801 that I admire but
with the flaws fixed, pg 96 in the .pdf: https://www.americanradiohistory.com/Archive-All-Audio/Archive-Audio/90s/Audio-1990-11.pdf
The main flaws are that one of the iron core inductors in the woofer path saturates,
it should be air core (no saturation), the woofer has DC offset issues "oil canning", all
issues at high power. VanAlstyne also found that one of the woofer inductors couples to
one of the midrange inductors - the simple solution is to desolder and move one of the
inductors.
Here is the Stratus Gold which has all air core inductors and does amazingly well in
the high power testing, note also the very flat frequency response, page 50 in the .pdf:
https://www.americanradiohistory.com/Archive-All-Audio/Archive-Audio/90s/Audio-1991-11.pdf
All of these systems are large and rather complex but take the listening experience to
another level.
I've A/B ed the OLA with the PSB Stratus Golds and while the Advents have deep bass
the PSB s go much deeper and will play about 9 dB louder (a lot).
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@TheFrugalAudiophile I printed out and tried to read Holt's article. I like Holt he
did a lot for critical listening and wrote some great reviews. I actually find that
article hard to read because, in my opinion his logic is flawed. I have a very different
perspective on audio, I prefer an A/B switch and a reference system. If you trust
the reference, you'll quickly hear flaws in inferior systems and perhaps a system
will sound even better than the reference but it makes it easy to remain honest.
It is a very complicated subject due to placebo and expectation bias.
I'll try again to read Holt's paper and see if I can put my objections into concise words.
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Do you have a supply of them or know where to get them, as I don't see them often on ebay?
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Nice work. Wondering about Xmax we could compute the wind height from
the number of turns.
Wire data: https://www.coonerwire.com/magnet-wire/
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That definition is wrong. A rheostat is usually a high power wire wound device, I've never seen
a strict definition but it is what I've learned over the years and I do think that it has only two
connections. I've seen EPI 100s with the level control and it is wired like a rheostat just adding
resistance in series with the tweeter, it is wire wound but not very high power. I also found 25
ohms from the factory.
I used 50W 8 ohm Lpads from PE in my own EPI 100 rebuild, because it is a better way to go
and much higher power.
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Those look great, I was thinking of trying a roundover but that looks nicer.
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http://baselaudiolab.com/ADVENT_LA_XO.html
Figure 5 has the schematic.
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Using the 5002 tweeters in OLA/NLA has been discussed here before. OLA has a 2nd order network
NLA 1st order but the 5002 has a 3rd order and it should be duplicated if you want to use the dome
tweeters. I don't think that the 5002 sounds as good as the OLA and would suggest going back to
the original tweeters.
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If you are up for it the Econowave Mod makes a lot of sense for your application. You
could use one waveguide tweeter with two woofers. I can explain it if you are interested.
If you don't want to do that, then the first question is what revision of the OLA are your
speakers? The first revision with the very light weight red dot inductors were known
to have the wire burn up and possibly short out. There was a tech note from Advent
about measuring the DCR of the inductor when replacing tweeters. I would just replace
the tweeter inductors with 18 or 20 ga air core if you have the dot type inductors.
Some of the tweeter resistors are near the switch and they were probably the source
of heat.
I've been writing this assuming you want to use them as PA speakers, are the Peavy s good
enough so that the Advents are going back to home use? I'll bet that the Advents had
better bass.
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Nice work!
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Poplar should be far easier than stapling into masonite or mdf, it should work fine.
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Is Poplar a Hardwood?
Written by Chris Deziel; Updated October 16, 2019Poplar is a hardwood, but it isn’t a hard wood. The most common species in the United States, yellow poplar (Liriodendron tulipifera), is found throughout the Northeast as well as in Canada, and it’s deciduous. The question may arise in your mind: “But is poplar wood strong?” and the answer is yes, but it isn’t as hard as most hardwoods, with a hardness rating less than that of some species of cedar, which is a softwood.
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I think .75" square poplar cut with the bevel might look better being less bulky looking than Glen's.
But of course measure first to be sure that everything fits and clears.
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Power ratings with speaker drivers are mostly wishful thinking. It is really very simple a 1" voice coil
wound on an aluminum former typical of a tweeter is most often good for about 10W RMS perhaps
15W with ferro fluid due to thermal heating. The average power in music is much lower than the peak
so many companies rate in system "Music" power. It is all a ratings game.
The other limit is displacement at the lower end of the spectrum for the driver, you want tinsel lead in
wires with a tweeter that is driven hard at the lower end of the spectrum and an overall "good" design
so that the wires do not break. You have determined that the Advent Tweeter fails under your use
condition, might as well try the Q1R and let us know how it goes.
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That AR-3a Improved crossover is nearly the same as the AR-11 with the noted use of
Lpads except for the tweeter cap going from 10 uF in the AR-11 to 4 uF. I would probably
experiment with 6 to 8 uF when using the AR-11 tweeter. I measured some peaking in the
stock AR-11 tweeter crossover section with the 10 uF and the level full up. I'd have to check
my notes on the measured crossover frequency.
I would not go larger that 4 uF with the older non-ferrofluid tweeter in the 3a.
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Here's a picture:
1. remove the strap on the red terminals.
2. loosen the screw caps for both red and the top (mid/tweeter) black.
3. connect the 4 ohm from lower red to top red.
4. connect the 10uF from the lower red to the top red.
5. connect the 20 ohm from the top black to the top red.
6. connect the amp connection to the woofer input as shown.
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Check the foam on all the drivers and check to make sure that the mids and/or tweeters are not blown.
I'll try to take a picture of how to set it up when I have a minute.
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They are looking great! What is the thinking behind RAF then Watco over it, isn't Watco Danish Oil
also a colored finish? I have used it but not over RAF.
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Nice work, I'm very pleased that we have another alternative!
AR LST crossover
in Acoustic Research
Posted
Would you please tell us where you got the new domes in case anyone wants to repair an
AR tweeter in the same way?