Andre_Db66
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Posts posted by Andre_Db66
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I do not remember there being so many red flags regarding asbestos 50 years ago. Nice anekdote, where i lived there was sheet asbestos used for shed roofing. When there was a campfire somewhere i would throw a piece of asbestos on top and after a while it explode with a loud bang. I would also steal lead from the roofing to melt and create tin(lead) soldiers. Both materials being toxic but hardly aware of the fact since i was only 8 at the time...
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2 hours ago, genek said:
Rock wool produced prior to 1980 is likely to contain asbestos. It shouldn't be an issue in a sealed cabinet, but if you're a tinkerer and may open it up again and again...
That is very disturbing to find out... i have been very dismissive of health and safety precaution. In another thread i am talking about why fibre glass is used in the first place as Goodmans and Kloss used foam sucessfully...
OTOH as a child i used to play in building construction sites jumping down floors into this stuff.... pre 1980.
Still here
I will be more careful and search for foam slabs to experiment because of both issues, fibre glass and resonances. I will copy the Advent/Goodmans method.
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Quick check with a tone gen tells me the frequency must be in the 500 to 600 region. This was with the LST with attenuator full open
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Pianos are difficult instruments to record....
Thank you for that video link.
I will let that play asap. When i conclude the flaw, i shall try diferrent speakers consecutively to eliminate upstream issues or possibly even room gain. It will take some time so probably sunday earliest i can commence. In the meantime when listening i shall refurbish my Sansui AU919.
I do know class D is something else... i am finding this a whole new way of listening to music. It makes AR speakers sing in a very different and distinct way. It is also very unforgiving. Most recordings apparantly are not mixed with this in mind as a lot doesnt sound right, but is the flattest uncoloured sound i have ever heard. There is amazing control of the woofer, which given the acoustic suspension is a major plus. It sounds extremely tight and much less boomy/woolly. My LST are now on class D, driven by a neutral Bryston. I have not yet tried a tube pre though...(paradox)
Andre
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25 minutes ago, Aadams said:
At 17:38 to 18:24 there are some obnoxious sounds emanating from that piano. I think it must be the way it is miked. I listened on AR3as and AR9. It was more apparent on the 3a. If your 3a mid pots are turned up past the mid point it would be awful. The LST mids are running at max all the time IIRC.
Gee.. thanks! I will dig into this a bit deeper when i have opportunity to find out if there are other examples i can muster. As i said there have been more occasions when i was surprised by this nasty sound. So it just became obvious that it was AR after i last heard it on my LST. They are hooked up to a class D that i only have a week. The last time i heard this was from a yamaha class a/b amp. I think I also noticed it with a modern tube amp. Problem is i have not noted down any specifics. I just disliked it. Since i have a lot of gear (GAS head), i shall have to focus on the problem. This will take more time than just emphasizing the last music piece i heard on AR, performing in this manner
(BTW... i tend to have tweeter pots opened up and mids tempered.)
First i might simply try a tone generator. It will pinpoint more precise i guess... I will try to find other examples.
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9 minutes ago, genek said:
For the AR-3a, the stuffing should be fluffed up and fill the cabinet right up to the front opening. The only space behind the woofer should be whatever is created by the magnet depressing the crepe or fabric barrier.
Fair enough...
I have plucked it apart completely putting small fluffy pieces in to make it more voluminous. It is not how i encountered it in virgin cabinets. Where indeed it was like you describe. I am using very thick constructiin fibre glass that i tear apart. I was wondering to place simply thinner layers in the manner as i encountered. That would be the way you describe it behind the woofer, but i cannot recall how it was behind the mid and high driver. Anyway, i think somehow it is playing a big role in my concerns...
It seems that it is either the mid or woofer not the tweeter. IMHO...
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17:38
That is around the region. Sorry lacking of time to find a music piece exacting more precise...
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43 minutes ago, Aadams said:
Solo piano? Which piano key? Or what frequency?
I yet have to test this with a tone generator as i have no clue which piano key it is exactly. However there is always the same note region that seems to be overamplified and stings the ear as it becomes very abundant and aggresive compared to the rest of the music piece. Judging by watching youtube piano music it is somewhere in the mid section of the piano, if that helps any...
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57 minutes ago, Aadams said:
Four speakers with an identical distortion flaw,in the same room, connected to the same source path, is an improbable speaker problem. The most likely source is dirt or a slightly loose connection upstream, especially if you are using vintage electronics before fader controls or digital circuitry.
I am not referring to the same hardware upstream. The speakers are producing this flaw with different electronics in that position, different room aswell. However, they have all been opened up and emptied of damping material at one point. There are undoubtedly cavities behind behind mentioned drivers and my suspicion is that the free resonance of those drivers against the backside of the baffle is causing this. At least, this is what i suspect because it sounds that way. I know that damping of mid and high drivers is crucial to avoid this kind of behaviour maybe i should just try what i mentioned myself. I have noticed seeing in either Goodmans or Advent speakers where the resonance chamber of the woofer is empty but the foam is only around the cabinet lining and behind the mid and high stuffed tightly.
I have opened up virgin AR speaker cabinets and there were slabs of fiber glass instead of torn up fluffy as i have replaced it. It is also only with the very specific frequency mentioned, otherwise playing terrific.
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I have discovered a very annoying fact about AR speakers i have. 2 sets of AR3a and LST perform the same way.
On certain piano notes or specifically that same frequency it becomes a honky sound as though there is a strong resonance added. It is very annoying and can become quite loud especially in case of piano music as that particular note can be emphasized by playin it louder on the piano. I dont know how to tackle this and if this is familiar to anyone here.
My best guess would be the glass wool has been in and out of the cabinet and needs to actually be placed in a specific way. The weight is known but is it for example that it should be mostly be stuffed behind the mid and tweeter leaving a cavity behind the woofer? It is now all fluffy spread in the cabinets and perhaps wrong approach.
Please any help is welcome as i almost find them annoying to listen to. The focus of attention is drawn too much here so it becomes unenjoyable. The drivers perfom well btw...
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That list is long. Philips here in the netherlands can be added.
compact cassette was their invention but Sony patented the walkman... 🤔
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.....🤐
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The fact that i am building speakers at home experimentally both sucessfully and unsuccesfully doesnt mean all the techniques have not been implemented before. If my outcome is great i can not patent it because i am toying with something which was invented long ago.
In the pioneer days however those boundaries were less clear or well defined. The persons applying the suspension first most likely also had a problem describing and patenting because otherwise Olson would not have stood a chance. That is my take on things. Olson did not invent something completely new but simply put, described it better and had that description officially acknowledged.
Vilchur otoh lacked the time and will to engage legal battles because he was probably skating on thin ice, and as mentioned before had already obtained public credit anyway, why bother.
Searching internet for Goodmans returns very little and as we are talking about a company founded 100 years ago, likely its close to impossible to retrieve the correct info. The company ceased to exist also. It also merged with Tannoy at one point. The name Tannoy being synonymous with the term speaker to the british for in every train station nationwide they would hang for PA objective. So not well known perhaps in the USA but both companies were majjor league. Tannoy now is chinese as many things unfortunately. That is how things dilute in the end...
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On 5/11/2024 at 4:48 PM, ReliaBill Engineer said:
Very little difference between the 2ax and the 5, other than the dome midrange vs paper cone midrange. And that’s easily solved.
I know, but i meant unbridging the xo on the 2ax, stacking them under the ar5 and changing the value of the inductor on the 10" 2ax woofers. So they become sustaining bass with lower cutoff under the ar5 which can then have the pots fully opened.
Placing this stack parallel it will be 4R so on a solid amp no problem. Today i bought a purifi class D amp 425 per ch@4R. It gives 450@2R so no sweat there.
I have tried this with active xo in the 3a stack and lst. It sounds quite nice. I made the cutoff very low on the ar3a's. Opened the attenuation switch more on lst and that sounds quite right. Mind you they are being triamped with equal amps.
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Fishy...
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I have an RCF 18" complementing the 2 sets of ar3a and lst with a dynacord digital xo, manipulated in windows. So bass is plenty.
I also have for sale a few 2ax speakers. As i prefer the ar5 perhaps i will first try uncoupling the 2ax with larger coil in combination with the ar5. Pots full open obviously. Problem when opening the pots is the abundance of mid and high and lack ing bass. I just love experimenting...
10 hours ago, ReliaBill Engineer said:I use my 2 Velodyne active 15” subs. Each has a remote for dialing in phase, cutoff, volume from my listening position. I have them set for 35 Hz low pass, 0 phase. Compliments the 2ax very well.
A very nice setup indeed!
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Just curious, does anyone know of a speaker that has been produced with the Olson designed patent applied? Brand, model?
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Someone said that the Philips dont give high frequencies, Quad esl57 also lack those higher range frequencies. Are they missed? No... i have reverted to eliminatin the tweeter and have reduced the 21.5mH to about 17mH. Now it seems the roll off became longer and there is more mid from the JBL. I will increase the amount of parallel uF by changing the capacitor to 533uF instead of 340uF. Listening tests will show if i am on the right track. Basically i indeed want the Philips full range without addition of caps or tweeter and an improvised sub running underneath up to approximately 50hz with second order butterworth.
I built a 832a single end amp with no feedback of approximately 3 watts p ch. I want this to go in the ring with the 2 x 300 watt SS. Bass units need a lot of damping factor especially in open baffle mount and stiff suspension is also required. The Philips drivers are high efficiency so it should match quite well.
I am thinking of abusing 3a speakers with bigger value inductors to work as sub woofers below an LST speaker. It would make a great match when the attenuation of LST is fully opened up. 4 tweeters 4 mids 3 12" woofers of which 2 would only reach until say 120hz. Much like an AR9.
I guess that is what those binding posts are there for... 😁
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But what about the key features?
If they are not properly described in a patent because in fact it is experimental and evolving datawise then someone performing an academical study on it, will always improve someone elses idea. This is in essence what happened with the mm and mc cartridges. Somebody invented the first system, because initially there was only a needle scratching the bakelite surface grooves and gradually that evolved into different suspensions and motors for pick up elements. Obviously it was in some way inventing the wheel over and over again up until the point that it almost becomes subjected to taste. Why do we prefer one cartridge or system over the other...? (I prefer MC 😁)
With air cushion suspension i believe it was no different. When you think about how Goodmans speakers work, their performance is almost a one on one copy of AR and i should imagine Olsons take on it. I have no idea at this point which speakers i have to look at for that. Failing to describe it in detail can spiral you into oblivion, but commercially, Goodmans were a succes. Vilchur probably obtained credit because it was better documented and commercialised to a greater extent. It all relies on the same physics principle though, thus reinventing the wheel. Probably memory serves those who claimed the invention last?
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And it also makes me wonder if Olson knew about the theory Goodmans applied without patenting and made a study out of that and then received a patent #
With inventors and inventions and the general public it is an obscure relationship. Tesla being one of them...
Tesla invented everything we associate with radio -- antennas, tuners and the like -- but an inventor named Guglielmo Marconi was given the actual credit. In 1943, the U.S. Supreme Court ruled that Tesla's patent had precedence, but the public already considered Marconi the father of radio [source: TAMMY].
Goodmans started back in 1923 producing speakers and earphones. Has many patents as well. I can not find any articles on the company founder though...
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I hope you got these speakers for free considering the extensive elbow grease you invested... 😁
Wonderful job, very admireable. I love people who spend the effort to fix things, thrown out by others as trash(ed).
Splendid work, enjoy!
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You should try stacking a pair of these in series. Easier load on a vintage amp and most impressive performance... i tried it with 300b push pull tube amp, i was blown away by the small footprint and size of the big sound. At only 30 watt 8R. Very affordable also
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Ok so this shows that the patent was applied earlier. It still doesnt prove or show how come Goodmans used this under a different name with the same purpose in the 1930's. Intelectual property theft before a patent was acnowledged i believe has been very common in some very great inventions. Earlier was mentioned the secrecy of working on an invention and therefore preventing this theft. I am only completely in the dark about Goodmans, there is no documentation i can find anywhere.
This discussion however does prove the inventors claim of AR of acoustic suspension to be false. The Goodmans brochure shows the system, be named differently, implemented commercially much earlier yet it was not patented.
I will experiment on a set of AR6 with the same type of foam as in the Goodmans and Advent cabinets, as i find the fibre glass horrible stuff... I wonder what type of material was used in the 30's.
BTW this type of foam is also applied in closed KEF speakers, so it is likely a myth to have to use that awful material for suspension purpose in AR cabinets. Here on CSP/AR, i only read about other specific acoustic material but foam isnt mentioned.
@Pete B
I read your topic and know your opinion of closed speakers vs ported and to great extent i have to agree. I own a set of First Watt F6 class A mono amps driving a set of KEF LS50 meta, which are very late tech, ported speakers with 5" bass drivers. The degree of stage and dimensionality is astonishing. Blind test i would swear i am listening to much bigger speakers. However, a set of Rogers LS3/5a closed cabinet speakers does the same, provided it uses room acoustics properly, it also returns 30hz audibly. Hence the approval of so many enthusiasts. My point being that first and foremost, placement in real life dictates performance and not anechoic measurement or anything like that (most listening rooms are acoustic nightmares, including my own). Human ear perception plays a great part in deciding if the sound is right or not. AR speakers sound right. But, so do many other brands... i will not start to name everything i have for this A/B comparison. It all remains subjective.
Electrostatic technology for example, Quad esl63, surpasses AR in clarity by far, yet beams a lot, hence the sweet spot. The perfect speaker does not exist, one has to listen to the artist performance live for that... (the sound engineer can screw that up though)😁
Cheers
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Old oak dining table, 2.5 inch thick, hollow and filled with bird cage sand. 100 pounds per speaker approximately.
Alnico JBL and Philips drivers
As you can see i am into reusable materials and technology. That also sparked my love for AR and Advent...
Potential critical load and deadly phase rotations, very severe descriptions for an open baffle system speaker that is used as nfm. I understand what you are saying and under normal circumstances where the speakers would be asked to deliver maximum power like in a computed box which is made with t&s parameters accordingly, this would certainly be an issue. As my open baffles are only used near field at 7ft, and the usage of drivers that are suitable but not specifically meant for this purpose i am mainly dependant on visual and auditorial inspection of the system. Read.... correction of the filters. When i play too loud the xmax limit becomes a problem for the K145 anyway, also for the AD1255. The latter being only 30 watt and highly sensitive will only allow moderate input from any given amp, tube or SS. The bass is turned up only so far to keep the balance right and carefully monitoring the xmax. The amplifier used for this is a professional amp which delivers a low impedance load without problems and also has clipping warning lights and overlaod protection. So i do not feel there is much to fear, i am safely playing music. A bump in the frequency range can be heard as it is unnatural and therefore eliminated simply by careful listening. The room is very small actually and the speakers are comparable to headphones this way, so anything that is not right will pretty soon give listening fatigue. I am on the right track, only need to tweak the lot a bit more...
As the philips is playing full range, the tweeter and 15" bass is only there to add the missing frequency ranges.
Annoying resonance in more than 1 type of AR
in Acoustic Research
Posted
Exactly what i omitted to do as i worked on the AR during fall and winter indoors... quite a few have been opened up. 21 cabinets to be exact.
Better late than never...