Friday, May 27, 2022

DLK Model 1 1/2 Loudspeaker Restoration

Unit: Loudspeaker System
Manufacturer: DLK
Model: 1 1/2
SN: 12994 & 13463

I bought these speakers a year ago from the original owner. The cabinets and grills are in excellent cosmetic condition. According to the owner, the woofers were re-foamed several years ago at Midwest Speaker Repair in Roseville, Minnesota. I didn't get a chance to test them before buying, but the seller claimed these speakers sound great. After some negotiations, we made a deal.

DLK_Model 1 1/2_After Restoration

I have read a lot of good reviews about DLK speakers on various audiophile forums but I have never owned them. DLK speakers were designed by Don L. Kliewer and built in Minnesota. To the best of my knowledge, there were many variations of the 1 1/2's over the years of production. This pair has woofers with rubber surrounds, DLK dust caps, phenolic ring tweeter, black foam padded grills, and solid wood cabinets.

There are also two versions of the 1 1/2 model with an impedance of 4 ohms and 8 ohms. This pair of speakers have a 4 Ohm impedance. 

I believe this is the 1st generation of DLK 1 1/2  speakers with the round terminal plate. Below is a specification for model 1 1/2 from the DLK brochure.

Woofer: two 8'' high compliance with low-mass cones
Tweeter: one 1 1/2'' direct-radiating
Frequency response: from 40Hz to 18.5kHz
Crossover network: 1st order series type. 6dB/octave slope. The 3000Hz crossover point is above the most critical midrange frequencies
Impedance: 4 Ohms
Recommended minimum amplifier power: 15 Watts
Recommended maximum amplifier power: 80 Watts
Cabinet dimensions: 24'' (H) x 14 1/2'' (W) x 12'' (D)
Weight: 38.5 pounds

So, before hooking up, I measured the impedance of each speaker to make sure there weren't any surprises. The measured impedance was about 4 Ohms. I then hooked them up to my Pioneer SX-770 receiver that I had recently restored, and... And I was very disappointed! The sound was coming only from the woofers but the tweeter was silent. I twisted the L-pad back and forth a few times but didn't notice any change. I pulled out the tweeter from each speaker and tested it. As expected, both tweeters are blown. I also pulled out the woofers and tested them as well. Fortunately, all woofers are still good.

I decided to restore these speakers and bought new tweeters from the Midwest Speaker Repair. The replacement part number is MT-4107-4. This is an exact replica of the original tweeter for this model. 

The original L-pads and capacitors in the crossover were also upgraded. I bought new L-pads from the Parts Express. The replacement part number is 260-255 (50W Mono, 1'' shaft, 8 Ohm). 

The original bipolar capacitor (10uF/50V) was replaced with a new MPT (metalized polypropylene film) cap made by SuperTech. This is a self-healing capacitor, rated from -40°C to 105°C with a capacitance tolerance of +/- 10%. 

Finally, all original wires were also replaced since I noticed the oxidation on several crimps. I used the 18 AWG stranded wires. I believe the original wires are 20 AWG stranded wires (no marking on them). New crimps are TE Connectivity, the part number is 42710-2.

The cabinets are still in perfect condition, with no scratches or dents. So, I just treated the cabinets to some Restore-a-Finish and Feed-n-Wax.

Below are some photos I took during my restoration process. The final result is amazing! The sound is smooth, with great detail, strong and tight bass, good midrange, and clear highs. These are very underrated speakers from the 70's. Please watch a short demo video at the end of this post. Thank you for reading.

DLK 1 1/2 Network wiring schematic

DLK_Model 1 1/2_Network Wiring Schematic

Both tweeters are blown

DLK_Model 1 1/2_Twetter_Blown

Original woofer with green frame and green cone - still in excellent shape

DLK_Model 1 1/2_Woofer_Original with green frame

Original crossover

DLK_Model 1 1/2_Crossover_Original

Crossover with new L-Pad and MPT capacitor

DLK_Model 1 1/2_Crossover_New L-Pad and MPT capacitor

Round terminal plate

DLK_Model 1 1/2_Terminal Plate

Replaced parts

DLK_Model 1 1/2_Replaced parts

DLK Model 1 1/2 - after restoration

DLK_Model 1 1/2_After Restoration

DLK_Model 1 1/2_After Restoration_with grills

DLK_Model 1 1/2_Back Side

Demo video after repair & restoration


  1. Very nice! I pulled a pair of these out of the closet where they had been sitting for many years. My wife bought them brand new back in the late 70s and she had them in her living room when I met her. One of the reasons I fell in love with her, probably! Anyway, I hooked them up to an old Harman/Kardon AVR20 II I had lying around and man, oh man, I had forgotten just how great these things sound. I pulled them out of the closet thinking I was going to try to sell them along with the HK but now I am having second thoughts. I think we are going to try to find a room to put them instead.

    1. Hello John, I totally agree with you, these speakers sound amazing. I was skeptical about their performance but read a lot of good reviews online and bought them when I had a chance. IMHO, these are very underrated speakers from the 70's.

  2. Have a pair waiting to restore, very good condition, series 1. plan to rebuild the crossovers as well. just finishing a pair of Klipsch KG2s, then these are next. Glad to hear I'm not alone!

    1. These should be very good bookshelf speakers after restoration.

  3. Having a hard time finding the replacement tweeters (I have te same 1.5 model) The PN listed does not come up on their site. Can you link me please?

    1. Hi Andrew, the link for the replacement tweeters is below. Just make sure that you are ordering the same impedance (4 or 8 Ohms) as your original tweeters. https://www.midwestspeakerrepair.com/shop/home-audio/tweeters/cone/mw-audio-mt-4107-phenolic-cone-tweeter-2/

  4. I worked for Schaak Electronics from 1977 - 1980, and the 1 1/2 was by far my favorite speaker to sell. At the price point there was little to compare them to. Nice, if not extended, highs. Exceptionally good midrange, and lots of punch. Put them with a high quality amp and they really sing. I'm thrilled to see someone bring them back to their full potential!