Anyone see these?

[ReliaBill Engineer]

19 hours ago, RoyC said:

I was just responding to Andre, who apparently misinterpreted your initial statement ("I may try a Chinese dome tweeter on my AR-4X speaker project...") before you clarified your intent.

Ok. Makes sense, mostly.

But that is just an experiment in the context of “what if”. In no way am I recommending it as a replacement. I just thought that since I have them, might as well try them. I originally bought them as a possible replacement for a 1992 bookshelf speaker pair I made. It currently sports a German-made polyamide dome tweeter that was popular back then.

Pretty much, this entire thread has more to do with tweaks and mods than anything original AR. Just my 2 cents.

[RoyC]

Just now, ReliaBill Engineer said:

Pretty much, this entire thread has more to do with tweaks and mods than anything original AR. Just my 2 cents.

Agreed.

[RoyC]

19 hours ago, Andre_Db66 said:

I thought the intended use of the vc  was to facilitate a drop in tweeter for any of the older models. LST, 3A/IMPR, 11, 10Pi and ultimately 5 with 8R coil. I do know there are differences between each XO.

I fail to see what should be done in the case of LST implementation though. As far as i know only a resistor has been applied in the craiglist offering.

Overall output and sensitivity are not the only parameters to be concerned with. Increased electrical resistance decreases output, but also affects the crossover point. Suspension compliance significantly affects the crossover point as well. The replacement dome you are discussing in this thread has a higher resistance (dcr), lighter dome, and a much more compliant suspension than any of the original AR tweeters resulting in a different response curve. A parallel inductor coil (not "vc", btw) can bring it closer to original by somewhat compensating for AR's (deliberately) stiffer suspensions. For the LST and LST-2, all the tweeters in the cabinet must be the same before you can begin work on the appropriate modifications.

In my opinion, based on your previous posts, the best you can hope for through trial and error is something personally satisfying. Nobody can do that for you...and your geographic location is obviously a handicap in that regard. Your best bet would be to start a thread in the mods and tweaks section to discuss your project.

[Andre_Db66]

Geographic location or not, paying 80 per tweeter for speakers purchased at the price of 450 is disproportionate. Why does vintage have to become a money pit?

I have responded to this thread because i have currently used these vc and that was the topic question. The result that can be obtained is already satisfactory but i am going to use the xo mods applied to later AR models. The dome is not perse lighter than a Tonegem version, both are linnen. There is resonance wadding present, i will place it also like in the Tonegem. The Tonegem is a generally accepted (improved) replacement driver.

It seems however that it is already decided that these vc are not compliant enough.

I have not seen any pictures or reference to other attempts using specifically these vc in this thread. Where are they?

I contribute here with best possible intentions to keep AR speakers (certain models) functional and have emphasized that this soluton is also applied profesionally.

Making this about me and my personal preference is irrelevant. The general public interested in these models of AR face the same problem of deteriorated performance in the tweeters after so many years, or broken wires. Perhaps all the discussion here gives useful insight in how to refurbish without dwindling on purist attitudes and calling it subjective remedy.

I notice this thread has been read a lot so has attracted at least some attention. Who is to decide what is right or wrong or useless but the audience.

I do not need to start a new thread about this topic as i distill my own information everywhere and apply it for my own benefit anyway. Quoting Frank Sinatra... "i did it my way".

Please remebember, no speaker is perfect...! Having a preference is subjective by definition. It is wonderful enough there is still a fair share of people with great affection for AR, regardless of their heritage, Vilchur, Kloss etc. They all were commercial in the end, one has to eat and pay rent at the end of the month, right?

The SRT i recently sold is a good example, they were not really known on this forum, yet scrutinized. I am a witness that they very much still produced a great deal of old school AR sound. I did not sell them because of lacking sonic quality, but due to their size. Having such an extended history, who or what actually defines AR sound?

Cheers

 

[genek]

Personal preference is pretty much the basis for this entire site. Otherwise, we'd all be listening to new speakers bought off the BestBuy website.

It's been a while now since the question of whether these could be viable restoration components, so it's time to move this over.

[ReliaBill Engineer]

6 hours ago, RoyC said:

Overall output and sensitivity are not the only parameters to be concerned with. Increased electrical resistance decreases output, but also affects the crossover point. Suspension compliance significantly affects the crossover point as well. The replacement dome you are discussing in this thread has a higher resistance (dcr), lighter dome, and a much more compliant suspension than any of the original AR tweeters resulting in a different response curve. 

That’s something I’ve never seen. If the VC is not changed, no change in magnetic circuit, no change in cone/dome material, no change in spider (spring constant), I’ve never seen a change in XO point just from tuning the suspension. The impedance resonance curve may change (Q) from more peaked to less, or vice versa. But the XO point won’t change. Not in my experience over the decades.

[RoyC]

It is often overlooked that crossover/response characteristics are heavily influenced by the mechanical properties of the drivers. Low compliance and high damping of the early tweeters simply resulted in progressively restricted movement of the dome at lower frequencies, yet large magnets were utilized to maintain higher sensitivity at the highest frequencies. Interaction with the midrange is affected accordingly. It's why the unusually stiff and highly damped tweeter domes of the original AR tweeters were used with just a single capacitor and no parallel components to cut them off at lower frequencies. It is also the reason a "crossover" design cannot be based on dcr alone, and why response measurements are required along the way.

When AR adapted the later, more compliant dome tweeter as a service replacement for the 3a, they reduced the tweeter circuit's original capacitance to 2-ish uf from the original 6uf by the addition of a series 3uf cap glued to the back of the tweeter (placing it in series with the cabinet's existing 6uf cap).  In the AR-11, which had the same configuration as the 3a, (same stated high crossover frequency), they used the more compliant cloth dome tweeter with with an added .1mh coil to cut it off electrically in a similar manner to the mechanically rolled off 3a era tweeters.

[Andre_Db66]

Using those methods it seems to me there is no problem implementing the china vc. It is may be even more compliant mechanically, but applying similar adjustments to the xo and batting plus inductor should do the trick to make a suitable replacement tweeter. It only take a scientific approach to achieve the correct result. My question earlier remains, why doesnt anybody with the right skillset and tools try it? Or have i misread and was it Ken who tried and failed to produce a good result?

I feel cornered, because it will remain a personal and subjective result if i go ahead and post my findings. I do not posess the skills and tools even though i am going to do it, just out of curiosity. For the community of AR lovers sake it would be better someone more educated in the matter should try it. Just my two cents...

I have 6 4R domes and 2 spare magnets.

Also i have a set AR5  already with 8R domes.

 

[dxho]

Someone with the skillset did try it and left a couple of comments.
Here's his first post  Here's the thead  , which sort of
stopped any further efforts in their tracks.

I believe this is Chris Vorius, the first one, as far as I'm aware, to
offer repairs on the original tweeters. Prior, there was nothing
close in sound to the originals. No one had succeeded in repair.

[ReliaBill Engineer]

21 hours ago, RoyC said:

 

When AR adapted the later, more compliant dome tweeter as a service replacement for the 3a, they reduced the tweeter circuit's original capacitance to 2-ish uf from the original 6uf by the addition of a series 3uf cap glued to the back of the tweeter (placing it in series with the cabinet's existing 6uf cap).  In the AR-11, which had the same configuration as the 3a, (same stated high crossover frequency), they used the more compliant cloth dome tweeter with with an added .1mh coil to cut it off electrically in a similar manner to the mechanically rolled off 3a era tweeters.

But this was a wholesale, whole scale change in the tweeter. So it required whole scale changes in XO components to allow an entirely different tweeter to “play” with the original XO cap. 
 

In the early tweeter, the VC inductance+XO-capacitor restricted low frequencies from entering into the tweeter’s circuit and response characteristics. High impedance to low frequencies.

A stiff suspension and high damping of the early domes resulted in high mechanical impedance, restricting power response/output.

[RoyC]

3 hours ago, ReliaBill Engineer said:

A stiff suspension and high damping of the early domes resulted in high mechanical impedance, restricting power response/output.

Yes, especially at lower frequencies. This was accomplished electrically (and more consistently/uniformly) with the later tweeter. The other drivers, cabinet volume, and crossover actually remained largely the same with later iterations of this design. The original tweeter's impedance (resistance/inductance vs frequency) is unique and cannot be adequately determined or compared by measuring dcr. The later tweeter was more uniform and reliable, and integration with a simple parallel inductor (not really a huge crossover change) was the beginning of the modern design. In the early days, AR's approach was to design and integrate proprietary drivers to physically work together with minimal electrical modification. The unusual suspension of the early dome was a product of this approach. It should also be noted that the AR 3/4" dome magnet and voice coil gap remained the same. I think we are in the same place with this, just using different terms.

Along with Ken Kantor, former forum member, Carl Richards, provided response measurements demonstrating the above relationships.

Andre...Ken Kantor's first recommendation was to use an AR-12 tweeter with a .07mh coil. The lower impedance Tonegen and AR-11 tweeters behaved similarly with slightly larger parallel inductors. Later work with the HiVi tweeter found a .05mh parallel coil to bring it relatively close to the original response, but dispersion was somewhat reduced. The 3a Limited of the early 90's used a .16mh parallel coil, and 4uf cap. Variable level controls were very helpful in all cases. (Bear in mind that this all had to do with replication of the original AR sound, which may not be relevant to this conversation.)

The replacement dome under discussion can be made to work fairly well. Its primary differences are a lighter cloth dome than any AR paper or cloth dome tweeter, and a much larger/softer suspension...resulting in a stronger and extended low frequency output. The replacement's (4 ohm) voice coil's dcr is a tiny bit higher than the original, and should not be a problem. In the absence of measurement tools, under the dome damping and treatment and suspension modification would have to be determined through trial and error. Crossover modifications may also be required for fine tuning. The good news is the goal is to simply find something subjectively acceptable.  (Bill, Based on your work with other tweeters this could be a project right up your alley.)

Roy

[Andre_Db66]

(Bear in mind that this all had to do with replication of the original AR sound, which may not be relevant to this conversation.)

My goal is not necessarily a change to this original sound, but a substantial increase in output compared to old worn tweeters. You have to admit their age is relevant to this dimise. (Above mentioned link i read about wadding clogging up the vc gap, i have only seen foam underneath which due to age turned to dust. That deteriorates original tweeter perfomance too)

This and the broken wires which often occurs and the low cost replacemnt part makes me look at the asian vc alternative seriously.

As we have discussed one of my 3a sets before, presumably having limited drivers i am now beginning to think that using the ar3a schematic was wrong.

So a recap of my 3 sets would be accurate if i say i own;

1 set improved completely original, rubber surround (old style tweeters)

1 set 3a with original 3a xo rubber surround. (Old style tweeters)

1 set with limited drivers and 3a xo and foam surround.(these drivers seem best)

The last set seems incorrect actually because it has the 3a xo.

I have been pondering on using my spare magnets to initially create a set of asian 4R tweeters to replace the old original tweeters of set #1 and 2.. However, i very much also like the improved fixed setting option as the open switch mode is reliable and cleanest sounding to my taste. Obviously the goal is to keep original AR sound. I am in the dark what steps i would have to take altering each xo accordingly. As a tower stack it is hard to distinguish the differences because it sound amazing but i tend to try and get my gear working the best way i can.

I have seen there are substantial differences in xo in all speakers that appear to have the same tweeters. I am referring to all, lst 3a impr limited 5 11 10Pi lst2. Caps coils resistors yet all differrent setups. Trial and error reminds me of my IT years, plug and play which we used to call F and prey... it would take me a long time to find a definitive answer to my questions concerning xo changes to match all my different 3a's much closer together.

Starting point i think would be the improved version with refurbished asian tweeter. Then match the rest accordingly. (Second set of refurbished tweeters and limited tweeters with necessary xo changes)

Any thoughts would be appreciated

[Andre_Db66]

Found this thread about the limited. There are no resistors parallel to the lpads

Would it be safe to assume that this is my starting point for my "limited" ar3a. Adding the tweeter section for the refurbished vc AR3a version, leaving the rest alone as they are original drivers. Also adapting the improved tweeter xo section to match this in case of a chinese vc tweak?

If yes, then i would only like to know how to eliminate the switches and pads and lpads.... to have 1 setting in all versions

[RoyC]

21 hours ago, Andre_Db66 said:

Any thoughts would be appreciated

-It is impossible to provide specific crossover and attenuation suggestions to accommodate unknown response differences between the original and your rebuilt tweeters...much less your preferences. Once you get your tweeters functional, start by using everything "as is" to begin with.

-The best way to determine your preferred level setting for your rebuilt tweeter is to set up level controls outside the cabinet, and measure the series and parallel resistance values of your preferred setting. You can then replace those values with fixed resistors. You can also try out different capacitor and inductor values in this way.

-It should also be noted that the short-lived AR-3a Improved departed the most from the other iterations.

 

[Andre_Db66]

What is different about the improved drivers?

It seems they are the same only the xo is different.

Judging by above schematic, using a normal 3a xo scheme is not suited for a set of tonegem limited edition drivers, am i right? For this is what i have done.

[ReliaBill Engineer]

On 6/23/2024 at 3:08 PM, RoyC said:

The original tweeter's impedance (resistance/inductance vs frequency) is unique and cannot be adequately determined or compared by measuring dcr.

Hmmm…

Adding a resistor (series or parallel) only adjusts the impedance “seen” by the XO. It doesn’t change the actual impedance curve of the driver itself. 

Padding resistors are commonly used by virtually all speaker manufacturers. They can be used to decrease the power response (sensitivity) of a driver. Using in parallel to a tweeter reduces the impedance “seen” by the capacitor and is used to maintain the intended XO frequency. The actual impedance curve of the tweeter is not changed. A parallel resistor usually also decreases the tweeter’s power response, since resistor bleeds off signal to the tweeter; no free lunch here.
 

When I add (parallel) a resistor to a tweeter to decrease its overall impedance, it’s just to match the intended overall DCR and combined impedance that the XO cap was designed for. It works quite well. It serves to keep the XO frequency as designed. Of course, no VC-magnetic driver is a flat resistive load; it’s a reactive load and it's a curve. 

[RoyC]

On 6/24/2024 at 9:11 PM, ReliaBill Engineer said:

Hmmm…

Adding a resistor (series or parallel) only adjusts the impedance “seen” by the XO. It doesn’t change the actual impedance curve of the driver itself.

Parallel inductors, not resistors, were used with the new tweeters to change the nature of the crossover to match that of the original mechanical roll-off properties of the early tweeters by decreasing/shaping the new tweeter's stronger contribution to the mid frequencies. The dome mass and actual dcr of all AR's 4 ohm 3/4" dome tweeters were very close. The later tweeter's significantly stronger low frequency response was due to different mechanical properties (ie suspension), and was modified primarily through the addition of parallel inductance. The result was a much more uniform, predictable response. As we know, the original AR tweeters were difficult to consistently manufacture.

Regarding resistors, series resistors alone will attenuate overall output but will also affect the crossover point. Parallel resistors can be used to maintain or create impedance characteristics as you described. When parallel resistance is used in conjunction with series resistance it becomes an L-pad. Variable L-pads are used to better maintain the circuit's impedance at different attenuation levels.

[RoyC]

On 6/24/2024 at 6:32 PM, Andre_Db66 said:

What is different about the improved drivers?

It seems they are the same only the xo is different.

Judging by above schematic, using a normal 3a xo scheme is not suited for a set of tonegem limited edition drivers, am i right? For this is what i have done.

The 3a Improved drivers are the same as the original 3a, but the crossover was changed primarily due to the elimination of the pots.

Tonegen tweeters were very similar to the AR-11 tweeter, but both were different from the original 3a and Improved 3a tweeter. The replacement you are planning to work with is different from all of them. Various iterations of the 3a can only serve as general templates or starting points.

[Andre_Db66]

Remember the other thread where i bought these 3a speakers. These have according to your judgment only latest Tonegen drivers implemented. The drivers were introduced by the previous first owner who purchased them through the official dealer network here in Holland. It makes these 3a cabinets very special and i doubt if the original 3a filter should be applied. I am therfore not only talking about different tweeters in this case...

The schematic i found and reposted, i am curious, is that an official copy to go with this driver set?

[Andre_Db66]

Perhaps i should apply the AR11 xo? In the brightest setting and no switches.

[Andre_Db66]

I just read, written by someone who was present at the time and involved with development of the improved version here in Amersfoort/Holland, that the biggest change was indeed the xo but most relevant was the fact they eliminated a lot of mid rolloff to the tweeter which resulted in much cleaner treble section. Also they were developed in Holland and built both here and UK. (UK performing that awful gluegob fixation issue) US department was not really keen on this entire development... They were not sold in the US. The early versions had the same drivers but later on impr also had the soft dome implemented. I dont have that version, mine are paper dome tweeters.

I also read about the changes to the woofer's Fo values, with the Tonegen having as high as 26hz compared to the 14hz first edition. I now uncertain if the Tonegen is the preferred woofer.

Also mentioning the pulverising batting material which entered the vc gap. I have mentioned earlier, that this was probably one of the reason for tweeter demise. Later this was changed to a different material, around 74 it states. I have not been succesful with removing any original vc because they were stuck in the vc gap. Being the reason i had to look for a different refurbishing approach.

I cannot quote any of this as it would take translation and that is a lot of work. All this was written in Hififorum around 06-2008.

[genek]

I would say scan and post the original and maybe someone can do something with it.

[Andre_Db66]

https://www.hififorum.nl/index.php?topic=12437.15

[genek]

Thanks. Google Translate does a halfway decent job on this.

The 3a Improved was indeed an all-Euro effort, and by the time it came out any of the people responsible for the original 3a who hadn't left the company along with Roy Allison were probably all working on the "next big thing," which would have been the AR-9 series. NIH may have been a factor in their disinterest, but it's just as likely that further work on a discontinued model wasn't likely to get budget approval by the Teledyne bean counters.

[Andre_Db66]

Wasnt it so that by that time Advent had stolen a fair share of the pie anyway? Sales were down for AR and huge for Advent... in US at least.

The AR3/a/impr/limited/reissue made a very incomprehensible evolution. All the changes and updates are not easy to catalog. Driver numbers, xo changes etc. Actually very hard to discern which version is best. Very confusing to the point of annoying.

I have 3 totally different version of 1 product.

Last week i bought a second set of Goodmans Magnum K mkI and they are identical twins sounding/looking completely uniform.

Air suspension resonating cabinet speakers which actually sound better or at least equal to AR3a. The same goes for a set of NLA i own. Competition was fierce and sales managers their job is to sell...

See my comment on KLH model 5. They are still at it is all i am saying. Driver/parts import from PRC is a common thing on US products(or Dutch) just to please shareholders. We outsource the tech to have it produced with cheap labour.