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Build a pr. of Frankenstein ADS

E

EddieE

Member
I first heard ADS L-710's on a showroom floor in about 1976.
I realized that I found the clarity and depth of sound that felt right for my ears.
Shortly after that I heard them I purchased a used pr. at a much cheaper price than new ones were going for.
No regrets, loved them for listening to rock, prog., classical, folk-rock.

Shortly after buying the beloved L-710's, my a neighbor was having a house sale and was selling a pr of AR-3a's in magnificent condition for cheap.
So I borrowed some $$$ from a good friend to purchase a second pr. of speakers.
Very different sound, less forward, but very detailed when listening to violins in my classical music.
But the ADS just could not reproduce that string sound that I preferred.

At the time I borrowed the $$$ I told him, who was also extremely impressed with the ADS sound, that if I could not pay him back the money in 4 weeks he could have the ADS speakers in exchange. Well he ended up with my ADS and was ecstatic, However, I was now the owner of AR-3a's, which I liked a tad more overall than the presentation of the ADS-710's. My dilemma now is that, although I'm set on keeping my AR's, I miss the depth and projection of the upper end of the 710's.

So, ..., instead of purchasing a second pr. of large heavy main speakers, can I build a proper volume cabinet ( i'm very handy wood worker) and assemble an smaller modified ADS speaker system with only crossover, tweeter, and mid range components using matched parts for a particular ADS model ???
It would essentially be a smaller "pr. of ADS" but sans the woofers.
I see ADS parts available for sale on internet.

I would set this 'aux. unit' on top of my AR's which sit on the floor so I could have option to select (an either/or switch) between the mid & high spectrum of AR's or ADS's.

[ I edited my text above to clarify my original question and goal, after I received a detailed response from Apreggiator]

​

 
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You can do this I guess, but there is way more to building good sounds speakers than just putting drivers in a cabinet. Do lots of research before getting started.
 
Q1: since 710s are air suspension, are the back sides of tweeter & mid-range isolated from the fluctuating positive & negative air pressures from moving woofers ? If they are then volume of built cabinets would not be a factor.

Q2: Can dispersion of waves emanating from tweeter & mid be optimized by duplicating surface aspect of top face portion of the actual source cabinet ? I could also match density of cabinet face material if necessary.

Q3: For the crossover circuity, can the woofer terminals be capped off leaving that circuit open without effecting anything ?

Q4: could volume controls (potentiometers) be included for each of the 4 components (two for each cabinet) ?

Best case senecio would be to find a pr of ADS where the cabinets were compromised, and use all parts, less woofers, and place in smaller construct cabinets for DIY project.
At anytime there after all components could always be put back into constructed cabinets matching original specs.

One goal is to save space by not having two prs. of large floor speakers stacked on top of one another.
 
Two different approaches..

Approach 1: The additional 'tophat'
1. The ADS's mid and high unit are sealed back, so cab volume doesn't matter. You could even do only a baffle on a 'foot'.
2. Recess the drivers into the baffle.
3, Add a radius to sides and top of the baffle. Read this (or something else about baffle step) for the foot of the baffle (that will be standing on the AR cab): Stepped Baffle Study
4. Put the AR's upside down, so woofer close to the 'tophat'.
5. Come up with a wiring scheme that lets you A. Connect all drivers inside the AR to its internal crossover and B. Disconnect the woofer from the AR's crossover but connect it straight to the ADS crossover woofer connections. You cannot leave the woofer part unconnected of the crossover as per your suggestion.


Approach 2: You could bridge the speaker 'behavior' gap through a combination of mods to the 'as-is' AR, no cabinet re-engineering or purchasing parts required..

1. Placement & Anti-Diffraction
~Felt Ring Mod: Line the recessed lip of the cabinet frame and the area surrounding the midrange/tweeter with dense SAE wool felt or carpet felt. This absorbs early cabinet reflections, dramatically cleaning up driver diffraction and bringing the upper-end depth and stereo imaging into sharp focus.
~Aggressive Toe-In: AR-3a domes disperse sound semi-hemispherically, meaning they lose energy if firing straight past you. To mimic the pinpoint projection of the 710, toe the speakers inward roughly 15° to 20° so the drivers cross just behind or directly at your listening position.
~Elevate to Ear Level: Make sure that the midrange domes align perfectly to your ears on the horizontal plane when seated.

2. Electrical/mechanical
~Recap the Crossover: Because the factory wax or Sprague caps drift wildly over 50+ years. Replacing the old capacitor network with modern, fast polypropylene film capacitors will significantly sharpen the transient response and depth of the upper register.
~Rebuild the Tweeter Suspensions: Original AR-3a tweeters have a urethane foam suspension holding the hard dome, which degrades and turns brittle over time. This cuts down on-axis and off-axis output significantly. Having them professionally reconditioned or updated will bring the factory projection back. Or.. Swap them out for HiVi Q1R soft dome tweeters (with a .1 mH parallel inductor coil).
~L-pad Bypass: You can completely bypass or remove the L-pad on the tweeter circuit. Wiring the tweeter directly to its crossover leg removes the series resistance block entirely, adding roughly 0.5 dB to 1 dB of raw top-end energy.
 
Like BmWr75 stated, “Do a lot of research before getting started”.

Yes my AR’s have never been recapped. And Im getting ready for second foam surround replacement.
I want to make sure that what ever i do can be reversed without compromising original AR design.
Thanks for ideas !
 
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EddieE said:
Like BmWr75 stated, “Do a lot of research before getting started”.
+
Q3: For the crossover circuity, can the woofer terminals be capped off leaving that circuit open without effecting anything ?
Click to expand...
=
Indeed.
 
EddieE said:
Like BmWr75 stated, “Do a lot of research before getting started”.

Yes my AR’s have never been recapped. And Im getting ready for second foam surround replacement.
I want to make sure that whatever i do can be reversed without compromising original AR design.
Thanks for ideas !
Click to expand...

Apreggiator said:
Two different approaches..

Approach 1: The additional 'tophat'
1. The ADS's mid and high unit are sealed back, so cab volume doesn't matter. You could even do only a baffle on a 'foot'.
2. Recess the drivers into the baffle.
3, Add a radius to sides and top of the baffle. Read this (or something else about baffle step) for the foot of the baffle (that will be standing on the AR cab): Stepped Baffle Study
4. Put the AR's upside down, so woofer close to the 'tophat'.
5. Come up with a wiring scheme that lets you A. Connect all drivers inside the AR to its internal crossover and B. Disconnect the woofer from the AR's crossover but connect it straight to the ADS crossover woofer connections. You cannot leave the woofer part unconnected of the crossover as per your suggestion.


Approach 2: You could bridge the speaker 'behavior' gap through a combination of mods to the 'as-is' AR, no cabinet re-engineering or purchasing parts required..

1. Placement & Anti-Diffraction
~Felt Ring Mod: Line the recessed lip of the cabinet frame and the area surrounding the midrange/tweeter with dense SAE wool felt or carpet felt. This absorbs early cabinet reflections, dramatically cleaning up driver diffraction and bringing the upper-end depth and stereo imaging into sharp focus.
~Aggressive Toe-In: AR-3a domes disperse sound semi-hemispherically, meaning they lose energy if firing straight past you. To mimic the pinpoint projection of the 710, toe the speakers inward roughly 15° to 20° so the drivers cross just behind or directly at your listening position.
~Elevate to Ear Level: Make sure that the midrange domes align perfectly to your ears on the horizontal plane when seated.

2. Electrical/mechanical
~Recap the Crossover: Because the factory wax or Sprague caps drift wildly over 50+ years. Replacing the old capacitor network with modern, fast polypropylene film capacitors will significantly sharpen the transient response and depth of the upper register.
~Rebuild the Tweeter Suspensions: Original AR-3a tweeters have a urethane foam suspension holding the hard dome, which degrades and turns brittle over time. This cuts down on-axis and off-axis output significantly. Having them professionally reconditioned or updated will bring the factory projection back. Or.. Swap them out for HiVi Q1R soft dome tweeters (with a .1 mH parallel inductor coil).
~L-pad Bypass: You can completely bypass or remove the L-pad on the tweeter circuit. Wiring the tweeter directly to its crossover leg removes the series resistance block entirely, adding roughly 0.5 dB to 1 dB of raw top-end energy.
Click to expand...
In response to Alternative 1 I sketched the wiring concept.
 

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My plan is to incorporate an ADS/Braun tweeters, mids, and x-over in my DIY project.
All would match a single model, or a combination if components were used across models.

However, I am now realizing that ADS/Braun 3-way bookshelf speakers come in both a 3 speaker arrangement (L630, L670, L760) & a 4 speaker arrangement (L710, L780, L810, L880, etc).

So given the rough draft of schematic in previous message do I have to stay with 3 component, or can I combine both leads coming off x-over for each of the dual woofer models ?
 
It appears that ADS replacement speaker components offered for sale on internet sites go for top dollar.

Q: Is the aftermarket product below (MW Audio) an "adequate" replacement for ADS tweeter pn. 206-0116 (orig. # 206-0100) ?
My application is for a DIY project.
MW Audio MT-4115: 1" Dome Tweeter / $44.95 ea.
From their website: MW Audio MT-4115: 1″ Dome Tweeter | Midwest Speaker Repair

4 ohm tweeter is a great replacement for the following models:
– ADS: Works well for many models, but some modification may be needed.
 

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I would like to say yes. These look to be the Peerless type model that Simply Speakers is currently selling (no affiliation). Part# K010DT on their site. They are a plug and play model for a L810 & any other ADS models with the same tweeter that the L810 used e.g., L710. I currently use these in my L810's. I've been burned too many times by sellers pushing burnt out units as good ones or ones that had crappy repairs and sounded like it. These replacements became my no brainier as i listened to both side by side and they were extremely close in sound quality if not identical. I bought 4 so i have spares.
 
EddieE said:
My plan is to incorporate an ADS/Braun tweeters, mids, and x-over in my DIY project.
All would match a single model, or a combination if components were used across models.

However, I am now realizing that ADS/Braun 3-way bookshelf speakers come in both a 3 speaker arrangement (L630, L670, L760) & a 4 speaker arrangement (L710, L780, L810, L880, etc).

So given the rough draft of schematic in previous message do I have to stay with 3 component, or can I combine both leads coming off x-over for each of the dual woofer models ?
Click to expand...
If you want to know what woofer you can connect, just make sure it matches in terms of nominal impedance (load in ohm)

Understanding dual woofer wiring:
Take parallel versus series wiring and how it affects speaker load (in ohms) into account.
Then verify at which nominal ohm load the original speaker was rated (the crossover terminals for the individual speakers has the same nominal ohm load).
Connecting speakers with a different nominal load than the intended load is not recommended to a crossocer without modifying the crossover as it will shift the crossover point up or down and lead to problems.

This is the basic picture:
images
 
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I broke down the concept that would allow me to enjoy the deep rich character of my AR3a’s while playing my classical & opera.

As well as having the ability to add the brighter end of ADS tweeters & mids to enhance the dimensional soundscape while listening to progressive rock.
The goal is to have this flexibility but not have two sets of rather large floor speakers in our (wife & I ) carpeted 15’ x 25’, 9’ ceiling back den that also includes 3 fabric pieces of furniture, 1 sofa and two
chairs. Nice space for sound.

My goal is to be able to brighten up the sound the AR’s a bit for some of my musical choices.
1) Without having two sets of large floor speakers,
2) with only one integrated amp,

One option is to incorporate ADS tweeters OEM 206-0107/206-0117 [Peerless copy 4-Ohm MT-4115-4], and possibly not include mids to not over complicate.

So, 100% of the time all three ARs components will be active with an option for upper end enhancement with ADS tweeters (and possibly mids) emanating from DIY ‘top hat’.

[ edited to correct poor grammar ]
 
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