Picked up a set of 3.1tl's, Here I go again

vintage dad

I have had a pair of 1C's which I modded years ago and love. Great bass and soundstage, big warm sound. But something has always been missing for me. A bit too rolled off on the highs, a bit lacking in detail. It isn't possible to tl a 1C. So 2 years ago I tl'ed a pair of 2B's. Rdo 198, Sonicaps up top, Clairity down low, Mills resistors, dynamat, hurricane nuts, sealed cabinets, etc. Great speakers! lots of detail, clarity, more musical. Love them too, but a bit bright and forward for me, somewhat fatiguing. So back to the mellow 1'Cs warmth and soundstage, but missing the highs and detail. I wished I could morph the strengths from both together. Invert the 2's on top of the 1's Advent style? (JUST KIDDING!) I settled on the 1's until I recently caught the fever again. After missing a pair of non tl 2.3's by 15 minutes I stumbled upon a set of 3.1tl's nearby on Facebook Marketplace. They were missing the left dimensional driver and interconnect cable but otherwise in nice shape listed for $600.00. I contacted the seller, he verified (verbally) that all the remaining drivers worked. I offered $450, he accepted. They were only 30 minutes away, so I picked them up immediately. I came home, hooked them up, and instantly regretted not testing them. (Stupid) Both tweeters fried. The good news is that I planned on taking the rdo 198's (and the MW6511) from my 2B's. The bad news is I felt I had been taken. I reached out to the seller. luckily, he responded immediately and refunded me $150.00. Whew. Felt good with the purchase at $300.

My first impressions of the 3.1tl's are very favorable! Just under the veil of the 30-year-old capacitors and complete lack of upgrades I can hear the beautiful sound waiting to be unlocked. They could be my missing link! Having rebuilt/modded several pairs of vintage Polks I am truly excited to tear into them. So here is where I ask a lot of questions.

I don't have a budget, but I am not wealthy. I am hoping the 3.1's are my last pair, but I have said that before. My space really isn't big enough for the 2.3, let alone the 1.2 so I guess I have reached my size limit.

I am pretty much set on Sonicap for the highs, have used them on my last 3 rebuilds. I am planning on stealing the 12uf Sonicaps from the other SDA pairs to save a few bucks. Since I will likely part with them both, I will replace those caps with less expensive ones. Plus, those Sonicaps are already broken in.

I feel like I know the answer but will ask anyway. Low pass caps. In my 1C's I used Daytons. In the 2B's I stepped up to Clairity. The 2B's definitely have more detail top to bottom. From reading posts I am wondering if the Clairity shunt caps could be responsible for the forward, sometimes harsh sound of the 2B's. Would it be well worth it to spend the extra money to go all Sonicap?

I read a recommendation to go with 2 27uf in parallel (54uf) for the 55uf shunt cap. what are the pros/cons of going with a 30uf and 25uf for an exact 55?

I prefer a little warmth. I have gone with Mills resistors in my previous builds but have read that they lack detail and transparency. I have read a lot of Polkies prefer the Dueland graphite silver resistors. Is the consensus that they are worth the additional cost? My recent search was only able to locate one 1.3 ohm. Are they still being manufactured? Any other mills upgrade resistor recommendations?

Lots of recommendations to spike the cabinets. I have been using heavy rubber feet. I have vinyl plank flooring over concrete slab and have some concerns about damaging the floors. Suggestions?

I am planning on giving my 2B's to my son. I am going to un-tl the crossovers and put back the rdo 194's. I robbed a 6511 from them for the 3.1's. A couple years ago there were MW 6511 replacements available online, as well as originals on EBay. That market appears to have dried up. The Speaker Exchange recommends a #6024 6.5 inch 4 ohm butyI surround woofer as a replacement. Has anyone used this? I understand I would need to replace both with a non stock option. there anything else I can use? My son is not a critical listener like I am, so close is good enough.

I will also be doing Dynamat Xtreme on baskets, hurricane nuts, sealing cabinets, replacing binding posts, and welding MW magnets.

Thanks in advance for the help!

F1nut

2BTL's are not a bright sounding speaker. What are you driving them with and what is your source?

1C's are a dull sounding speaker no matter what you do to them.

vintage dad

F-1 nut, You (and others) actually helped me with the 2B's in June of 2022. They aren't overly bright or forward, I am just searching for a sweet spot between the 2 and 1. I have an Adcom GFP555, Hafler DH500, Onkyo7030 CD player, Blue Jeans RCA's generic speaker wire. The onkyo was a budget replacement for my Rotel CD11 which I found to be bright.

F1nut

Try adding a .2 to .5 ohm resistor on the positive lead to the tweeter. That will dull down the top end a bit.

Might try some better RCA/speaker cables.

Consider a Marantz CDP.

MW6511's right here, https://forum.polkaudio.com/discussion/200754/mw6511-mw6510-mw6503-rd-0198-sl3000-blowout#latest

vintage dad

Thanks for the lead. DM sent. Will consider Marantz for next CD player. My Dual 1229 turntable is nearing completion at No Transistors so that and the 3.1's will be draining my bank account for now. I have enjoyed the SDA1 and 2, but am eager to move on to the 3.1tls. I re read my 2022 discussion and found that you answered the all Sonicap and spike questions back then'.

gmcman

When I read that the 2B's were bright, my thoughts also were it's not the speakers, especially with the RDO-198's and Mills.

Is your Adcom and Hafler still original? If so, my guess is your gear is likely in need of a refresh, mainly the caps. I would want to swap a modern integrated to see if the sound quality improves to your satisfaction, or another pair of separates but an integrated might be easier to test.

audioluvr

When you updated the 1C crossovers did you replace the poly switch with a 0.5 mills resistor? You could try going with a 0.2 ohm one which would brighten it up some or upgrade your speaker cables with some with silver in them.

Gardenstater

Try some wool tweeter pads. That cured any brightness issues I had with my 7Bs after crossover and internal wiring were done. I actually enjoyed listening to Breakfast In America after that.

xschop

I have a spare 6502 you can try in place of the 6511. That Speaker Exchange substitute might sound ok, but looks like azz.

It has been a long while since I heard a set of 1C's. They were not dull sounding, but rather peaky with the SL2000's at the time.

"From reading posts I am wondering if the Clairity shunt caps could be responsible for the forward, sometimes harsh sound of the 2B's. Would it be well worth it to spend the extra money to go all Sonicap?"

Simply try foaming the inside of the MW's frames. From my experience, the lower-end Dayton caps are just veiling the cone/basket reflections that cause "shouty" midrange at even moderate listening levels.

vintage dad

audioluvr wrote: »

When you updated the 1C crossovers did you replace the poly switch with a 0.5 mills resistor? You could try going with a 0.2 ohm one which would brighten it up some or upgrade your speaker cables with some with silver in them.

I have a jumper in place of the polyswitch

vintage dad

gmcman wrote: »

When I read that the 2B's were bright, my thoughts also were it's not the speakers, especially with the RDO-198's and Mills.

Is your Adcom and Hafler still original? If so, my guess is your gear is likely in need of a refresh, mainly the caps. I would want
to see if the sound quality improves to your satisfaction, or another pair of separates but an integrated might be easier to test.

I am planning on having gear refreshed at some point. Dont get me wrong, both pairs of speakers sound awesome, I am just making critical comparisons.

vintage dad

xschop wrote: »

I have a spare 6502 you can try in place of the 6511. That Speaker Exchange substitute might sound ok, but looks like azz.
A 6511 for me.


Thank you for the offer, F1nut found

vintage dad

Thanks for the replies guys, but the main purpose of my discussion is updates for the 3.1tl's. After listening to them stock I am confident they will be my new favorites after updates. I have already removed the rdo198's and a 6511 from the 2B's and installed them in the 3.1's.

lawdogg

Congrats on the 3.1TLs!!

vintage dad

I think my questions may have gotten lost in my long post. I am getting ready to order my caps. For the 55uf shunt cap am I better off going with two 27uf (54uf) or one 30uf and one 25uf (55uf)?

vintage dad

Simply try foaming the inside of the MW's frames. From my experience, the lower-end Dayton caps are just veiling the cone/basket reflections that cause "shouty" midrange at even moderate listening levels.[/quote]
I have heard of using dynamat but the foam concept is new to me. What kind of foam do you use.

F1nut

vintage dad wrote: »

I think my questions may have gotten lost in my long post. I am getting ready to order my caps. For the 55uf shunt cap am I better off going with two 27uf (54uf) or one 30uf and one 25uf (55uf)?

Either will work, but if it was me I'd go for the exact value using the 30 and 25.

xschop

vintage dad wrote: »

Simply try foaming the inside of the MW's frames. From my experience, the lower-end Dayton caps are just veiling the cone/basket reflections that cause "shouty" midrange at even moderate listening levels.

I have heard of using dynamat but the foam concept is new to me. What kind of foam do you use.
[/quote]

@Gardenstater idea. Very worthwhile mod.

https://forum.polkaudio.com/discussion/195562/must-try-mod-foam-inside-the-stamped-steel-baskets-yes/p1

vintage dad

I just finished un-tl'ing my 2B's by removing the 5.4 sonicaps and reinstalling the RDO194's. They sound great. I dont know what the issue was with my tl mod, but the brightness is gone. They sound well balanced and musical with slightly less detail. I used a jumper in place of the polyswitch rather than a resistor. I previously had a Mills.68ohm resistor in that spot with the RDO198's and they were still hot. Go figure. My non tl 2B's will occupy the place of honor in my system until the 3.1tl's are ready. Then I will likely gift them to my son.

Tomorrow begins the breakdown of the 3.1tl's. I have everything but the capacitors. I went Clairity CSA all the way but Madisound was out of the 12mfd's so I will be waiting until they are back in stock. Plenty to keep me busy in the meantime. Glue magnets and Dynamat Xtreme the midwoofers, refinish and seal the cabinets, install hurricane nuts, new grille cloth and binding posts. Need to get some spikes as well. I may take some pics as I go, but usually forget to pause once I start rolling.

F1nut

Supposed to be a 5.8uF cap, not 5.4.

gmcman

The 5.4 would allow more midrange or bass into the tweeter, shift the curve for the most part. I assume that was a typo?

Do you also have the 3.2 ohm resistor in place with the jumper?, or a 2.7 ohm with the .5 ohm or .68 ohm?

What was your total resistor value when you had the RDO-198 installed?

vintage dad

I typed 5.4 from memory, it was in fact a 5.8. The .68 resistor was in the polyswitch position and the 2.7 was in parallel with the 5.8 cap. Total resistance would have been 3.38 ohms

Gardenstater

I figured it was a typo because as far as I can tell, Sonicaps don't have a 5.4 value available.

Maybe no point to asking now, since you did away with the tl and the 198s but how did you choose the value of 0.68 ohms for that resistor? Did you measure the resistance of your polyswitches when you took them out? I think when they are new they measure more than 0.68 ohms, or say, when they have been pretripped a few times.

F1nut

The polyswitches measure 0.5 ohm on average. Hence the recommendation to replace with a .5 ohm resistor.

Gardenstater

F1nut wrote: »

The polyswitches measure 0.5 ohm on average. Hence the recommendation to replace with a .5 ohm resistor.

I thought I had read that at some point MP switched Polk policies to pre-tripping them. This shows that for the RXE050, which is the one they used in the early 2Bs according to the schematic, that after tripping the measurement standard is 1.17 Ohms. FWIW.

F1nut

Measured a few over the years, some at .5 ohm and some slightly higher, but none close to 1.17 ohm. At 1.17 ohm the tweeter would be obviously muted to one's ears.

vintage dad

I did a discussion about the 2B's being bright 2 years ago. It was suggested that I step up from the .5 ohm to a .68 ohm, so I tried it. It's sometimes difficult to pinpoint what didn't sound right, but I can use a musical example. I am a fan of the Tedeschi Trucks band. They are from Jacksonville FL where I live. I have been to several of their shows and I have met them personally. On their recordings her voice is rather forward. When the 2B's were tl'd her voice was overbearing, almost harsh. I would fatuige quickly when listening. It wasnt that way on my 1C's, and now that the 2B's have been tl deleted her voice is so much smoother, but missing the detail of the RDO198'S. The 2B's are now a bit more musical with better highs than the 1C's, but I miss the bigger soundstage and bass of the 1C's. I am really hoping my 3.1tl's will pull everything together.

vintage dad

Pulled all the drivers and the crossovers today. I believe I am the first to break into this pair, no stripped screws, everything is pristine. All of the drivers are correct, magnet stickers still firmly attatched. I love that the large coil is attached to the crossover with screws on these, I have always hated those little plastic clips. Someone said in a post here that Polk skipped on the cabinet construction on the 3.1 but I dont get that impression. There are 10 internal braces. Seems pretty solid to me.

vintage dad

New Cardas binding posts

gmcman

@vintage dad while you have the drivers out, I can say possibly the single best upgrade I did to my 2.3TL's was the internal wire upgrade. I did that last and it really brought all the upgrades together and maybe that was why it was so noticeable.

I would seriously consider it if you are on the fence.

As far as the 2B's, I remember wrestling with a slightly bright setup and that's when I was using an AVR and a Denon 2910 DVD player. Once I changed that to a Marantz SA8004 (later upgraded to the SA8005) and the B&K Ref 50/ 200.2 combo the 2B's really sounded great, the slight brightness was gone.

Toolfan66

vintage dad wrote: »

Someone said in a post here that Polk skipped on the cabinet construction on the 3.1 but I dont get that impression.

I say they did, my biggest issue with the 3.1’s is the top and bottom caps are not removable like other SDA’s, I purchased a set many years ago that was in rough shape, was looking forward to redoing them, when I noticed they were part of the main cabinet, and one of the caps was split, I was done at that moment. I ended up parting them out.. 😔