Documenting: My SDA-1c upgrades from start to finish

F1nut

There's an aspect about doing modifications that hasn't been addressed yet and should be given serious consideration, reversibility.

Crossovers - can be easily reversed or the hack jobs that some do can be redone properly.

Spikes - easily reversed.

BH5 - easily reversed.

Rings - can be reversed by changing the mounting hole locations.

Gaskets - stock is still best, but damaged ones must be replaced. Avoid Mortite.

Binding posts - cannot be reversed, but there's no real reason to do so. Can be changed to ones you prefer.

Dynamat Xtreme - unless one has unnecessarily covered every square inch it can be removed with little effort.

Tweeter plates - easily reversed.

Gluing the magnets - should never be reversed.

Phase plugs - cannot be reversed.

Foam lining the basket - good luck getting that crap out. BTW, that foam will turn to dust one day and make a big mess.

External cabinet mods - may or may not be reversed depending on what was done.

Reasons to consider reversibility. You may not like the results and they don't make these anymore. You may wish or need to sell the speakers at some point and potential buyers may be put off by what you've done resulting in a serious negative impact on the value.

Gardenstater

plastic_avatar wrote: »

Gardenstater wrote: »

Is that a Technics SA500 and a Dual CS606? If so, you have my college budget setup right there.

Ah, close.

Realistic STA-960 and a LAB-420

Realistic made some solid stuff at one time, and I wanted that turntable for AGES. Found it for $35 in Pittsburgh 2 years ago. MINT, with an Audio Technica Signet stylus and a couple of nice Stantons. The Signet lives on the no-frills Ariston Q Deck, and I put one of the Stantons on my Luxman PD-272. Annnnnd I put my nice Shure on the Dual 1219 I put in my GE console... The remaining Stanton is on the LAB. There's your TMI for the day.

And yes, let's talk more about how proudly thrifty I am.

https://www.vinylengine.com/library/realistic/lab-420.shtml

I'll check those out. I like reading about vintage gear. I paid $50 for my Crown D150 lol lol. So I understand needing to watch the budget. I saw that my Technics SA500 sold for over $300 on eBay not to long ago. That was a shocker. I still have it in the box. I used to blow fuses on the Polks with that, probably from clipping 🤣. I just looked up my receipts and it turns out I paid over $1000 for my gear in 1979. That wasn't exactly cheap back then ha ha.

plastic_avatar

That's a good start on the mod list caveats, @F1nut.

I changed it a little for my purposes.

---

A list of mods for ye olde Polks!

Reversible:

- BH5 to rear inner wall of cabinet
- crossovers
- gaskets (you just need to keep the originals)
- outer cabinet mods (like felt around drivers or extensions/changes to edges for diffraction)
- rings (metal pieces to brace the rear of where the midwoofers mount)
- spikes (but you'll have holes in the bottom of the cabinet...)
- tweeter plates

Hard (or just tedious) to take back, but not impossible:

- lining the inner basket of midwoofers with Armacell or similar
- using your choice of aluminized rubber to cover the outside of midwoofer and passive baskets

Mostly, practically, not reversible:

- gluing magnets
- installing hurricane nuts/bolts
- phase plugs (though there's a thread of someone who did so to fix)
- replacing binding posts and/or SDA connectors (unless you make your own replacement mount and save the original in a box for future generations)

---

OH! I forgot I was going to design a replacement mount for the terminals and SDA cable!

To Tinkercad, Boy Wonder!

ken brydson

Gardenstater wrote: »

@plastic_avatar AFAIK you are on track to be the very first person to do the phase plugs AND the foam inside the basket mod on an SDA model! How does that feel? 😉

Gardenstater

Stay away from Kelly, Al ! Personally I would prefer a picture of your daughter Kelly next time, although Mr. Bean is a riot.

plastic_avatar

plastic_avatar

'Mark the time, ensign.'

'Aye sir. Time of thread death. 17:59 hours.'

xschop

Once you hear the SDA soundstage in those phase-plugged towers, you'll be digging in the crates for all your old material.

The foam frame mod has NOTHING to do with, or affect what the BH5 does, because it is the FIRST LINE OF DEFENSE against frame-to-rear-cone reflections as Gstater spelled out.

P.S. @F1nut

You spoke too soon...The phase plugs ARE reverseable. I've reversed a set and will reverse another set soon to design a copper shorting ring pole-piece for the vintage MWs...a real LEGEND driver if you will.

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Gardenstater

And I would like to add, actually in reference to the unproven statement that the Armacell inside the baskets "will turn to dust someday", that nobody is concerned about the foam in BH5 or Sonic Barrier turning to dust......er uhh.....are they? Armacell is marketed as pipe insulation and needs to hold up over time. I think the 3 things that will degrade polymer foams the most are: Heat, Ultraviolet Rays, and Ozone. Being inside of a speaker enclosure will do a pretty good job of protecting against all 3 of those.

We will all turn to dust someday but that shouldn't stop us from enjoying life.

Unknown

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F1nut

BH5 and SB are completely different materials, actually a combination of materials, compared Armacell.

Gardenstater

I'm not losing any sleep over it. I'll report back here on the condition in 5 years. I think what I said stands unrefuted regarding UV and ozone and heat exposure. Not all foams are created equal either. Armacell, as I said is probably more robust than many foams that are not for heat and cold pipe insulation. Solid company. Solid product.

Has anybody reported crumbling of their often touted Armacell speaker gaskets yet?

plastic_avatar

@pitdogg2 I'll look at that in just a few minutes. Thank you!

Side notes on other things, just since I'm thinking:

My reasoning for putting the Noico/insert-aluminized-rubber-mat-of-choice-here on the interior passive walls on my Monitor 12 is for the same reason as the backing on No Rez. Just to go back and touch on something here. It very much helped tame the boominess, and I don't feel a reduction in the low end where it matters (clean tone and tight bass).

I very much would like to try a BH5-like material in lieu of matting.

I can see how the BH5 could be detrimental to sound (and the link explains that a little bit) if we use too much.

I do want to do (at least) the Noico-type covering on the passive chamber of the 1C. I don't see how it would affect it in the negative, *for me*, since I like the difference in tone on the 12. It might not be anyone else's cup o' tea, but I am super pleased with the results. I am out on whether or not I would , Sonic Barrier, No Rez, or diy something to use anywhere by around the mids and the tweeters.

Since I'm on the diy train, I'm curious about a No Rez approximation.

Now off to look at Sonic Barrier

plastic_avatar

Oh! The link I forgot to add!

https://www.youtube.com/watch?v=uDXC6TkaQ1E

xschop

This iteration currently serving in my XS-8TL's and my last set of Billet 5Jrs. Best sounding version to date with the foam frame inserts. I even took out 1/3 of the Dacron with no detrimental effects. Mids are phenomenal and the bass hits hard and articulates every detail of the notes. No "life" lost out of the music...

plastic_avatar

You've been holding out on us... Do tell about the mass you've added to the bottom!

xschop

I posted it somewhere here before and I built a set of CRS+ with the stand-offs.

These have white hard-foam stand-offs that attach to 2 ea 1/2" opposing layers of open-cell Soundcoat encasing a layer of butyl mat and 1/8" layer PVA foam.

VR3

I have used no rez, sonic barrier, bh5

All of them are extremely detrimental to your sound if you use to much and to much is very easy to do

Gardenstater

I listen with my ears, not my eyes. Steven, I checked my small horde of shim stock that I have again, and now I am getting 0.0065", the same as the stuff I used to make my 4 shims I used for the phase plug install.

If you want I will part with enough of this to make 8 laminated shims. I'll even make them for you. Just send me your address in our PM.

xschop

Toolfan66 wrote: »

I will admit I like the phase plug idea, but I don’t like the way it looks on these MW’s, I don’t like the transition from where you have to cut the dust cap to the phase plug, and as it has been said these MW’s are becoming more scarce every year.

I fully agree with Jesse, this thread is what not to do, it seems we have a few threads like that..

I'm strictly in it for the sound, secondarily for the aesthetics. Steven can always go back and add the very small foam ring to that area for looks if he pleases. Ive found that sonically, it's unnecessary.

Gardenstater

plastic_avatar wrote: »

Oh! The link I forgot to add!

https://www.youtube.com/watch?v=uDXC6TkaQ1E

I had seen this before. What is missing is mention of passive radiator speaker applications, where the reflection off the enclosure walls may be a key element of low bass response. He talks about a vented enclosure with a fully driven woofer only. We should try to ask him to address this in a future video.

I think it is perfectly fine to try to dampen your panel resonances though. I think this stuff (acoustic absorption foam) should stay out of the passive chamber completely and I would stick to what you have used previously which is the Noico. That and some additional bracing might be the way to go. 3/4" hardwood dowels are something I want to experiment with in my speakers in a couple key places. Just my 2c.

plastic_avatar

Well, this escalated quickly.

WARNING! WARNING! Danger, Will Robinson!

To put things in perspective for late-comers and participants alike...

Accepted mods/upgrades done or in-progress

-crossovers (caps and coils (though people get sporty about cap brands))
-SDA cable
-new gaskets
-Hurricane nuts/bolts
-metal braces (rings) behind midwoofer mounts
-removable felt diffraction pad for exterior around tweeters
-aluminized rubber on exterior of baskets (though how applied and how much is in question)
-create custom tweeter plates (though there are doubts from some about my 3D printed variants)
-custom terminal/SDA cable mounting plate
spikes
-the DreadKnaught or DreadKnought or Dreadnought or...

Contentious mods/upgrades done or in-progress

-Wuhan tweeter dome upgrade
-created custom tweeter dome backwave diffuser
-adding bevel to tweeter plate around dome
-phase plugs for midwoofers
-Armacell on interior of midwoofer baskets
aluminized rubber on interior of passive baskets
-additional material on back wall behind midwoofers (BH5, No Rez, Sonic Barrier, my crucified body)

Asked-about and thought about or previously done mods/upgrades not yet in-progress

-different open cell foam products in different parts of the cabinet (side question: don't passives act more like reflex than sealed enclosures?)
-dowels for bracing interior front face around passive
-extra sound-trapping material behind/attached to midwoofers
-aluminized rubber on interior walls of passive area (I am 100% pleased with how it affected my Monitor 12, so I'll likely do it to my 1C,)
-stands to get speakers to the appropriate height for a given listening area)
-altering or adding to cabinet edges to address diffraction

----

I *think* that covers it.I wrote this after I got out of bed this morning. I may have forgotten something .

Though, I didn't list freshly sacrificed chicken blood as a substitute for Murphy's Oil Soap.

Coils and a Dread are on the 'waiting to see if I can justify another $600+ on a pair of speakers I already have $1100 invested in', not because I'm cheap, but because I have a family I put ahead of myself.

And no, I don't care if I get even a third out of these if I have to sell them. That's not why I'm doing this.

I'm not exactly an idiot when it comes to all of this, but I am really low on the scale from just-a-guy-who-loves-audio-who-got-a-grant-to-start-a-speaker-business that never took off back-in-the-day, to the incomparable @DarqueKnight and the rest of you really knowledgeable (and astonishingly thorough) folk, though others have called me otherwise.

Side note: Anyone know who at Polk oversees the forums? Anybody have an idea who's in charge of actually approving the funds to keep this active and assigning mods/admins? I'm grateful for the resource, and the friends I've made. I'd like to send him/her/them a msg about the support, instruction, data, positive experiences and help I've gotten from almost everyone

I tried sending a general email once, but no response.

If it wasn't for this forum, my pair of Monitor 12 would still be rockin' original tweeters and *maybe* a $50 crossover re-do. But now I'm a Polk person fixing/modding 2 more pairs of vintage kit. That makes me happy.

lawdogg

plastic_avatar wrote: »

Well, this escalated quickly.

WARNING! WARNING! Danger, Will Robinson!

To put things in perspective for late-comers and participants alike...

Contentious mods/upgrades done or in-progress

-Wuhan tweeter dome upgrade
-created custom tweeter dome backwave diffuser
-adding bevel to tweeter plate around dome
-phase plugs for midwoofers
-Armacell on interior of midwoofer baskets
aluminized rubber on interior of passive baskets
-additional material on back wall behind midwoofers (BH5, No Rez, Sonic Barrier, my crucified body)
-using hanger bolts to spike your speakers

Thought I'd add one that this thread hasn't mentioned. I'm maybe a little guilty of pot-stirring a few years ago. But maybe spiking would come up here at some point?

https://forum.polkaudio.com/discussion/172908/budget-spikes-spike-your-sdas-for-under-3/p1

lightman1

Best mod ever

plastic_avatar

@lawdogg Stir that pot! STIR IT!!!

I had spikes in the accepted part, but missed bulleting it in my pre-ambulatory thumb typing this morning =P

[reads your thread]

Glorious

I was looking for cheap spikes.

I used dome-headed bolts for my RTi10... When I got them, the spikes were missing and a foot bracket was broken.

@lightman1 I thought about braiding some coathangers for another user. Don't tempt me.

Right now, I'm thinking about printing a blank board to use for my crossover, rather than the stock setup... but nit sure what kind of wire to use for the connections... because I know there are opinions from people who know a lot more than me on this point.

The coathangers would be to stiff [laughs].

audioluvr

lightman1 wrote: »

Best mod ever

Is that the OCC version?

plastic_avatar

@Toolfan66

Meaning the number of participants and the number of comments since my ringing basket update. And a reference to the arousal bits.

Given how escalate is used in meme-dom, I can see the confusion. I should've used a different intro.

I'd change it to 'All this was a lot to catch up on!' or 'So many comments to go back and make sure I keep track of!' or 'Hit the brakes, I need to collect my thoughts!' or 'O.k., let's take stock of what I have here, because, going back through and reading, some people think I'm an idiot, or cheap, or disrespectful because I'm trying something non-standard or off-the-wall (or even just tossing ideas out to see what people think).'... or something, to avoid confusion.

I did say I wrote that long-**** thing when I woke up... and the thoughts cross 3 or 4 different threads.

I certainly wasn't complaining about anything you said! You're helpful!

plastic_avatar

No problem!

My essays are prone to errors/typos/things I wish I could fix.

More words = more chances for [insert unintended consequence here]

plastic_avatar

Now.

Printing a terminal plate and putting a few things up for sale to fund coils