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Stacked Advents: Do I need to isolate them from each other?


Norman Nicolai
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I have a question about stacked Advents that I don’t think I’ve ever seen addressed: Should I be concerned about isolating the top Advent from the bottom Advent?

I’ve rediscovered my stacked OLA’s since purchasing a new Power Amp with much more power than my previous amp. I have the cabinets arranged in the recommended way, with woofers top and bottom and the two tweeters close together in the middle. Recently, using the new power amp, I’ve noticed much more vibration from the speaker cabinets, probably because I’m cranking them louder than before. If I leave something on the cabinet of the top speaker it now vibrates which it never seemed to do before. The speakers are in my basement “cave” with vinyl tile over a concrete floor. The bottom speaker sits on large bricks with some felt feet and some cotton fabric between the bricks and the speaker cabinet. There is a thick cotton towel between the top and bottom Advent cabinets. 

Do I need to isolate the two speakers more from each other more? Any Ideas on what I am doing wrong before I start to experiment with different set-ups?
 

 

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I don't isolate mine but the top speaker does eventually displace from the bottom one and I have considered putting some kind of friction material between the two, which is what you need. Cotton towels won't stop the movement.

My vinyl ones aren't a problem because the vinyl provides enough friction, itself, but my Walnuts are. Keeping them absolutely level helps.

My only concern is that whatever I use will mar or discolor the surfaces, which I don't want.

I've known some guys, in my life, who probably would have nailed the two together. The same kind of guys who would use duct tape for surrounds. :D

Doug

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You mean duct tape is not good for speaker surrounds???

Kidding, of course….

Both my sets are walnut OLA’s. I had a set of OLA’s paired with NLA’s originally, but there was a thread here on Classic Speakers about NLA’s really being closer to 4 ohms than 8 ohms, so I D/C’d the NLA’s in the stacked configuration over concerns that it would drop the impedance significantly below 4 ohms. I finished restoring a set of OLA’s about 5 months ago and started stacking them with my, original, older OLA’s. They absolutely sing now that I have them paired to a SS Mitsubishi power amp and a Conrad-Johnson tubed preamp. I now prefer the stacked Advents over my restored AR-2ax speakers. I don’t know what it is with Advents, but more is definitely better…sorry, I digress.

I have to have the speakers elevated off the floor over concerns about basement flooding. I had about an inch of water in my basement 15 years ago, so everything down there is elevated off the floor, thus the stacked bricks.

I made a couple of speaker stands last year out of wooden 8” high wine crates. The wine crates were sanded and finished with spar varnish, then filled with sand. They are incredibly stable and heavy and are the perfect size for my Advents. I think it’s time to move them down to my basement, replace the stacked bricks, although I’m dreading carrying the heavy stands down 2 flights of stairs. 

I have some coarse heavy felt that I may try between the two speakers. And I think I may try to make sure they are perfectly level, which they are not, due to basement floor being off a bit in my 95 year old house.

I’ll post again after those two changes.

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On 12/9/2021 at 3:28 PM, Norman Nicolai said:

They absolutely sing now that I have them paired to a SS Mitsubishi power amp and a Conrad-Johnson tubed preamp. I now prefer the stacked Advents over my restored AR-2ax speakers. I don’t know what it is with Advents, but more is definitely better…sorry, I digress.

Hi Norman

Interesting stuff. I remember the pair of OLAs I restored and I was sadly underwhelmed, much preferring the AR-2ax. Sadly I no longer have the OLAs or the 2ax's but I wonder whether your excellent amp/preamp upgrade is what makes the stacked Advents superior and, just a thought, what stacked 2ax's would sound like in an apples-to-apples comparison. But, like you, I digress....

So I was wondering whether the 2 cabinets were isolated or tied together in the original configuration. Seems to me Sorbothane rings or mats would work well for isolating them. Search ebay for "Sorbothane" and you'll find lots of products. To couple them you'd need spikes or something and that would mess up the veneer. Personally, I'd use Sorbothane.

I searched for the original TAS article and found it. Unfortunatel there is much discussion of fusing and amplifiers but none regarding exactly how to stack the speakers.

Good luck. Hope some other members (with experience with stacked Advents) can give some good advice.

Kent

 

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2 hours ago, JKent said:

what stacked 2ax's would sound like in an apples-to-apples comparison. But, like you, I digress....

Kent, I have to make a little digression too ...
I stacked AR2 on top of AR2a (previously on top of AR2 there was AR1MS as a mid / high section to the AR2 woofer only) and I entered another world! the bass are more than doubled, I did not expect it and the rest of the range accompanies beautifully, never heard the AR speakers with 10 "woofers sound like this, the total sound is very balanced and the speakers disappear ... I thought about it above, I concluded that I got 2 pairs of AR2s with an AR-ST added in the middle of them !!

wall2.thumb.jpg.82e1038c7c5e1f902246a25e58868f8c.jpg

The AR18s don't play with the AR2s

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As per the recommended stacking instructions included with early-1970s Dynaco loudspeakers, I have always achieved good results by stacking them horizontally rather than vertically, so that both woofers & both tweeters are fairly close together.   A small towel placed between them sufficed. 

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On 12/9/2021 at 5:40 AM, Norman Nicolai said:

about isolating the top Advent from the bottom Advent?

Here is Nicolai the cork discs with exact measures of diameter and thickness: personally I put one among stacked speakers (among other things it allows the rotation of the cabinets in a safe and atraumatic way for the veneer), I put two if the cabinets are positioned horizontally, such as under my AR LST stacked on top of the AR3a and AR10TT! Perfect as well as allowing air circulation between the cabinet bases!

wall83.jpg.c1bdc4713b92cc4c0667db3f0250b3fe.jpgwall84.jpg.99360f498e480592912cbee6b00124d8.jpg

 

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  • 2 weeks later...
On 12/11/2021 at 7:00 PM, Martin said:

As per the recommended stacking instructions included with early-1970s Dynaco loudspeakers, I have always achieved good results by stacking them horizontally rather than vertically, so that both woofers & both tweeters are fairly close together.   A small towel placed between them sufficed. 

I typically liked all of my smaller speakers horizontally stacked as well...AR3's, KLH Six's, Advent's.

 

Can't do that with this coupling however. The 3's are toed in dramatically to line up it's tweeter to the Allison One's. I've had them horizontally placed as well on top of the A1's, but this was suggested to me by somebody who's knowledge I trust, and I like how it sounds. Also makes it easier toget to the back of the 3's if I want to adjust the controls.

 

And yes, that is a Xmas tree on the left. Suffice to say we got tired of needles and water, and didn't want the standard fake tree.

 

 

 

 

F7-A8-E793-8512-4-F68-8-CF2-4-FA2-CD6870-C2.jpg

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Sorbothane will 'bleed' and leave a oily like stain on any surface. "Blue-Tack' may be better, although it also will tend to excrete an oily stain though less so than sorbotane. 

Why would you even consider "isolating" as both cabinets are vibrating in similar fashion?  I wouldn't be worried about a cabinet vibrating off of the bottom cabinet unless you are using high volumes and then, you'd see any changes occurring and correct it. Ultimately, if you are unnecessarily worried then, use a cheap smallish metal strap on the back of each cabinet to anchor one to the other with small wood screws.

In my situation, my speakers are heavy enough where I don't worry and again, both cabinets are vibrating at the same frequency.

FM

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  • 4 weeks later...

Based on the feedback I got here, here is my solution:

1.  Solid base. I have an old 1/2 wine case that I refinished to serve as a speaker base. I added about 30 lbs of sand to provide stability. 
 

03260A0C-1F49-4D46-9602-EE7A1066B1B0.thumb.jpeg.8d7bb7250a1db14b38ebecd2cb06ea05.jpeg
 

2. I got square cork board and added two layers between the speaker base and the bottom speaker.

579AA9BB-9460-4B01-8775-8BB71D781DB0.thumb.jpeg.1393f38fd602980ce074e7f43d63b888.jpegimage.thumb.jpg.c6684e8df1dfe497c63dc0454f062387.jpg

3. Lastly, I used the same cork board and added two layers between the top and bottom speaker.

0DD996A7-086D-46D1-804D-99A43247E38B.thumb.jpeg.5700e02e598ad37270ae40614b3adfbb.jpeg

So far, so good. I don’t hear any vibration, and I feel far less movement and vibration from the speaker cabinets.  Not sure if the audio is improved, but I can place something on top of the top speaker now and not have it vibrate and buzz.

I have not done a great deal of listening yet to tell how well this is working, but if there are any problems, I’ll post again.

Thanks for all the replies to my post, and all the input!

 

 

BF733234-94C9-4F7C-AA2C-CED7B0AAE2A4.jpeg

Edited by Norman Nicolai
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  • 2 weeks later...

After listening for a couple of weeks I can’t honestly say that the stacked Advents sound any better with the new arrangement. But as I said in my last posting, I can now place an object on the upper Advent and it does not vibrate like before. I suppose that lack of vibration should translate to better audio, but I just can’t hear it. (68 yr old ears, maybe?)

JKent, one thing I am certain of: Stacked Advents respond to more power! They sound improved now that I have them connected to a more powerful amplifier, in this case, the Mitsubishi DA-A10. The Advents now sound better across all the audio frequencies, but the difference in bass response with the new amp is remarkable. On a whim, I swapped out the Conrad Johnson tube preamp for the preamp in my rebuilt Advent 300 receiver, and to my amazement, it sounded better still. I continue to be impressed by the Tomlinson Holman preamp in that amazing receiver. (Thank you T. Holman and H. Kloss!) The highs were sounding just a bit shrill with the Conrad Johnson and there are no tone controls to knock down the treble just a notch with that preamp. By comparison, the Advent 300 preamp sounded balanced with both tone controls set at the neutral position. Then again, don’t forget that I have 68 yr old ears, and I’m basically a tube guy who responds favorably to slightly rolled off highs…

 

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On 1/19/2022 at 1:34 PM, Doug G. said:

Actually, cork does seem like a viable material. I'll have to see about getting some.

 

Doug

Doug, this is the stuff I ordered from Amazon:

NTReasy Cork Bulletin Board , 12 x 12 Tiles , 1/2 inch Thick Wall Bulletin Board, 4 Pack with a Box of Basics Push Pins Tacks

If you copy the text and paste it into Amazon, you can het the same stuff I used.

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  • 4 weeks later...

I use these springs under some butcher blocks to isolate some turntables. I don't see why they wouldn't work  on stacked Advents.

Audiocrast Speaker Isolation Base Pads, Spring Speaker Floor Protector, Sound Dampening Anti Vibration Non-Slip Speaker Stand Feet Shock Absorber for HiFi Amplifier DAC Recorder 4PCS (Silver) https://www.amazon.com/dp/B08MPBXG6M/ref=cm_sw_r_em_api_glt_i_WRYKEZ3ZBN90R9XPT35S?_encoding=UTF8&psc=1

OgmoigF.jpg

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On 3/6/2022 at 4:04 PM, lARrybody said:

I use these springs under some butcher blocks to isolate some turntables. I don't see why they wouldn't work  on stacked Advents.

Audiocrast Speaker Isolation Base Pads, Spring Speaker Floor Protector, Sound Dampening Anti Vibration Non-Slip Speaker Stand Feet Shock Absorber for HiFi Amplifier DAC Recorder 4PCS (Silver) https://www.amazon.com/dp/B08MPBXG6M/ref=cm_sw_r_em_api_glt_i_WRYKEZ3ZBN90R9XPT35S?_encoding=UTF8&psc=1

OgmoigF.jpg

I'm guessing that those are two very well-isolated turntables...^_^

SL-1210, correct? The record clamps look interesting, too!

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The first table is a 2008 SL-1210 Mk5 that I found in a pawn shop in 2010. It was missing some parts so I sent it to KAB and it came back with mods and like new. I told my self that I would never get rid it. To stay true to my word I ordered a SL-1210GR with a Nagaoka MP-200.

It only took 8 months to get. I have more expensive turntables, but I sure like these. They are the M1 Abrams of turntables. How much better could the G model be?

Lately I have been on a isolation kick. I have experimented with spikes, springs, foam and cork. Now I am compilating putting some KEF bookshelf speakers on stands on top of some powered subwoofers.    

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Yeah, KAB is quite a resource for the SL-1200, and audio accessories/upgrades.  And Mapleshade is another company that's been working with isolation methods for a number of years.

I purchased a NOS SL-1210 MK5 from B&H several years ago, and replaced the arm with an SME 3009 MKII using a very clever stainless steel adapter plate that was listed on eBay. Surprisingly, it seems relatively immune to LF sounds, and I once had a subwoofer positioned directly below the turntable.

I've got to say, I'm really impressed with Technics' modern replacements for the SL-1200 series; price-wise, and in terms of engineering, fit and finish, they are simply outstanding.

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