Any experiences with DLK 2s?

[b1daly]

I’m trying to rescue a pair that I picked in a pile of junk, so they were pretty rough.

I’ve finally got to the point of putting all the drivers back in, and they sound bizarrely lacking in deep bass.

For anyone interested, these are a three way speaker. 12 inch woofer (heppner I think) 5 inch mid (heppner) and a phenolic ring tweeter.

The tweets I replaced with one of the reissues that you can find in various places. I only had one good original, but can compare, and in someways the copies are better...not so bright and little “paper coney” sounding, but more smooth and higher extension.

The Mid’s I got on the auction site from someone who said they were pulled from DLK 2s. But they have much smaller magnets. They are also heppner drivers and drop right in (the basket has more of a square shape, but holes and cutout are fine. )

Again I only have one original, but at least I can compare. They sound different largely in the same way as the tweets, more paper cone sound, but much smoother and less harsh.

The issue comes down to the woofers. They just seem to have a high fundamental resonance, so they are push towards 120 to about 250 hz, there are some deeper lows, but they are relatively attenuated.

The result is, especially with the newer drivers, is very midrange heavy. It sounds like the woofers are overlapping, like all the drivers are overlapping a bit, resulting in a very dull, boxy sound. The old drivers lessen this a bit, but I feel like the issue is the woofers.

I did try switching polarity in the Mid’s, and I’m sure I have it right.

The 12 inch woofers have an accordion style surround, treated cloth or something. And the are very stiff, with much less driver excursion than I’m used to with foam or rubber surround. They are original, they actually have the DLK logo on dust cap.

But pushing in the drivers, they feel very stiff, almost like guitar amp speakers.

The other changes are I recapped, and replace the original electrolytics on tweeter and mid with Dayton film caps, and the woofer with a new non-polarized cap.

The originals had some kind of loose cellulose filling which was gross and deteriorated. I replaced with polyfill didn’t cram it full, but a modest amount.

The cabinet has a port, and after first listen I went back to make sure the filling wasn’t blocking the port.

Anyhow, it blew my mind that a very heavy cabinet with a 12” woofer and a port tube would render such wimpy bass.

I’m now left pondering that age old question “is this how they are supposed to sound?”

There could be various elements but from what can hear the 12 inch woofer just doesn’t generate much deep bass. I wonder if the doping on the surrounds might have stiffened up.

Overall, not a bad sounding speaker, but the voicing is off.

Thanks for reading, if any has any comments I’m all ears

 

[HomerJSimpson]

I wonder if the doping on the surrounds might have stiffened

This is exactly the problem. Those woofers should easily move when pushed in.

 

[crazy-in-az]

Maybe the magnet shifted and the voice coil no longer moves like it's supposed to. That would explain the stiffness and lack of bass.

 

[Lux Man]

You say they don’t generate much deep bass. So that’s a subjective statement. What are you comparing them to? I’ll be open though, my first speakers were DLK 3’s. In my opinion the dlk line was just okay. Shaack sold a bunch locally but I’ve never been impressed. The 4’s might be ok if you’re looking for deep bass.

 

[macgolf]

No experience with DLK speakers but have had success with loosing up 10" drivers, with stiff cloth surrounds, in 2 pair of 3-way speakers. These 10" drivers ran unabated through about 8K so closer to full-ranger than than a woofer. Still they were lacking bottom end and their sensitivity was far below the manufacturers printed claims. They were supposed to be triple digit efficiency but couldn't measure up to my 90db speakers.

After ensuring the woofers were wired correctly, I treated one of the 1st pair with petroleum jelly and played them. It took a few weeks before a channel imbalance developed. Treated the other and gradually returned the balance knob to the center. Picked up another pair a year later with same driver and issues. In the meantime I read a thread from someone who used baby oil. Did both drivers at same time and followed with petroleum jelly. Took less time but normality was restored.

I didn't have much in the 1st (or 2nd)pair so there wasn't a lot to lose with experimenting. YMMV.

Mark

 

[b1daly]

No experience with DLK speakers but have had success with loosing up 10" drivers, with stiff cloth surrounds, in 2 pair of 3-way speakers. These 10" drivers ran unabated through about 8K so closer to full-ranger than than a woofer. Still they were lacking bottom end and their sensitivity was far below the manufacturers printed claims. They were supposed to be triple digit efficiency but couldn't measure up to my 90db speakers.

After ensuring the woofers were wired correctly, I treated one of the 1st pair with petroleum jelly and played them. It took a few weeks before a channel imbalance developed. Treated the other and gradually returned the balance knob to the center. Picked up another pair a year later with same driver and issues. In the meantime I read a thread from someone who used baby oil. Did both drivers at same time and followed with petroleum jelly. Took less time but normality was restored.

I didn't have much in the 1st (or 2nd)pair so there wasn't a lot to lose with experimenting. YMMV.

Mark

Thanks for all the comments. I’m going to ponder treating the surrounds.

One thing I’ve noticed as I’m messing around with the various mids and tweeters, if there is just a hint wider frequency response, or slightly shifted mid point, giving more of an overlap at the crossover point, it can have a surprisingly large subjective effect on the sound.

Especially in a marginal situation. You can have a speaker that is midrange heavy, but confortable, add a touch more midrange to the overall response and it becomes unacceptablely colored.

 

[b1daly]

You say they don’t generate much deep bass. So that’s a subjective statement. What are you comparing them to? I’ll be open though, my first speakers were DLK 3’s. In my opinion the dlk line was just okay. Shaack sold a bunch locally but I’ve never been impressed. The 4’s might be ok if you’re looking for deep bass.

I think of deep bass as 80hz and below... there are two interrelated issues, the quantity of energy below a given frequency, and the frequency response below that cutoff.

To my ear these speakers are generating sound down to 50hz or so, but way to much between 100-200, which to my ear sounds weak and muddy.

These are the first DLKs I’ve heard. I heard a few folks who are fans, so I thought they would be interesting to restore.

 

[Lux Man]

I understand some out there may be fans of DLK, most likely for nostalgia or they live in the Twin Cities which is where DLK's were made. In my opinion, once again don't get caught up into trying to make a silk purse out of a sow's ear. In this case that's what I see being attempted. I had the 3's in 1976 ,thought they were great but I'd take the original large Advents in a heart beat over the DLK 3's.

Have fun experimenting.

 

[mnrocketry]

A few questions, more for my own curiousity...

Do you have 1st-gen (foam grilles) or 2nd-gen (fabric grill, mid & tweet mounted behind a big silver plate) model 2s?

Did you clean and lubricate the L-pads? I've restored a lot of DLK speakers, and the L-pads for the mid and tweeter levels usually need attention. I can usually pop the cover off of them and use Deoxit products. I've also ended up replacing some that I either couldn't get open or that were broken internally.

I own two pair of 1st-gen DLK 2s that I've restored. I honestly haven't listened to them in almost two years (for various reasons). I recall that they have the accordion style surrounds on the woofers. Now you have me curious; I should dig them out and see how easily the woofer cones move.

 

[b1daly]

I have the first generation, with foam grill pads. I did deoxit the L-pads, they seem to be working correctly.

One issue I have is I only have one original midrange...I found a pair on the 'bay that the person claimed were from a DLK 2, but they are quite different. So I wonder if it's from the second generation? I much prefer the original, it has a much bigger magnet, a brighter sound, and the DLK logo. But so far it's been "unobtanium."

The issue with the bass is definitely with the surrounds on the woofers. One is noticeably stiffer, the surround is crustier, and it has less bass.

I'm trying to decide on what might be good for cleaning the surrounds. I'm leaning towards isopropyl alcohol as it seems to clean a lot of things pretty well. It is a pretty strong solvent on some things, so I will try and test on a little area.

The goal at first would be to remove any crusty junk, then evaluate what kind of further treatment might loosen and protect them. The surrounds have the folded accordion style, and are coated with a dark rubbery substance. It attracts debris which sticks to it.

I appreciate all the comments. I decided to try and refurb these speakers mainly because I had them, and I was interested in learning about this era of speakers.

I now have assembled one original speaker, with the tweeter and midrange, and the better woofer, and it sounds pretty good.

It's a different type of sound than I'm used to. At first I was amazed to learn that so many speakers came out that didn't extend to 20khz. Upon listening, I can see one can get a very pleasant sound anyway. At my age, I'm down 15db at 12khz anyway. I can still hear something above 15khz, but not much.

One thing I'm finding out is that the reissue phenolic ring tweeters sound pretty different. I've obtained a hodgepodge of older phenolic tweeters, and they all sound different!