Portable Record Player Upgrades Incl. Cartridge/Platter/Retrofit Counterweight

Needing a self-contained record player with a very small footprint for use on a cluttered desk, I considered the Coturn CT-01 and the reissued Audio Technica Sound Burger. However, these rechargeable models lacked features I wanted - no speaker/s (however basic), no standard battery option etc. - and, though excellent, seemed rather expensive for occasional casual listening. Instead, I acquired a few pre-owned budget alternatives at rummage-sale prices (a Crosley Revolution and some others) for possible modification. All were fitted with the screechy ceramic cartridges, sapphire styli and heavy Skywin-type tonearms common on low-cost units. Some also rotated at hopelessly erratic speeds. However, the Ion Duo Deck (it doubles as a cassette player), didn't exhibit the latter fault and had all the features I required, including a speaker. It did, however, have the same cartridge/arm issue, which I wanted to avoid.

I therefore had to upgrade a cartridge without a standard fitting and also devise a counterweight for a tonearm that wasn't meant to have one. Here's how I found some advice about the first problem and then solved the second with a wire clothes hanger and a computer motherboard standoff! As these modifications worked well I added a few off-the-shelf accessories as further enhancements.

[A brief aside: this is a case study relating to this particular model. There are simpler ways of making a counterweight for other Skywin-based designs, such as using self-adhesive tire weights (https://www.youtube.com/watch?v=2gKhLTaKUY8 - nice idea!). However, the Duo Deck doesn't have enough space behind the tonearm pivot to allow this, hence the need for some lateral - or more accurately vertical - thinking.]

Here's a full (I think!) list of all the tools and materials I used. You may find you don't need all of them. To avoid clutter I've just included the less common items in the photo (marked *).

Tools

• A measuring tape or rule.
• A pair of robust wire cutters.
• An aerosol can or similar to use as a wire former.
• A heat gun or other heat source.
• Some digital calipers for measuring gauges accurately.*
• A miniature drill or reamer.*
• A mini-wrench, nut spinner or some small pliers for tightening the standoff.*
• A stylus balance, ideally digital, for adjusting the counterweight.*

Materials

• A wire clothes hanger. The one I used had a wire gauge of 2mm, but there may be some leeway.
• A standard computer motherboard standoff. A 10mm shaft length is ideal. Slightly longer may also work, but anything shorter than 10mm won't provide enough support. They come in various thread lengths, of which 5mm is best for providing enough anchorage without undue intrusion. If you've ever worked on desktop PCs you may well have one in your box of screws and oddments.*
• About 10"/26cm of sleeving to cover the wire (optional). Pulling the wires out of a piece of scrap cable is an easy and cost-free way to obtain this.
• A small ferrule that will fit over the above sleeving (also optional).*
• About 1"/2.5cm of heat-shrink sleeving of a gauge to suit the wire.*
• Additionally, some off-the-shelf items are described in the first step. Of these, the upgraded cartridge is essential (the counterweight won't work with the standard model fitted to these units). The other items are useful but optional.
• A very small amount of epoxy adhesive.

A few more optional extras will be suggested as we go along.

[This step is more about buying stuff than proper Instructablism, but bear with me...]

I'll start by sending you somewhere else!

A YouTube video uploaded by VWestlife, expert optimizer of otherwise unlovable audio equipment, describes a suitable cartridge upgrade that will in fact fit this non-standard headshell. It's a clone of a classic BSR model that's also ceramic but is far superior. Rather than plagiarize his content I'll let him tell you all you need to know about identification, sourcing and installation (but see the note about cartridge options in the following step). Go there, do what he suggests and then come back here for the next step!:

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

The very small platters on players of this type can mean poor stability, so I replaced the Duo Deck's 4.25" silicone platter mat with a full-sized rigid acrylic mat as seen in the introductory photo, thus effectively installing a full-sized platter. This may seem perverse given the unit's ultraportable nature, but the 12" mat is of course removable and in any event dealing with one more 12" disc-shaped object is hardly an issue when playing a stash of LPs. Adding a record clamp or weight also helps. Audio dealers, Amazon and eBay can provide these items at various price points. Being optional I didn't cost them against this project specifically, plus I could of course also use them on other turntables. Additionally, I attached a self-adhesive handle (there's actually no obvious way to pick this player up!) and some extra feet on the opposite side to allow suitcase-style parking. I also added a spirit level.

While the new cartridge will be much better, the non-adjustable tonearm/headshell/cartridge assembly still weighs far too much - mine came in at 6.3g! This is necessary for the rather crude original cartridge/stylus to stop it from skipping but absolutely not for the upgrade model. While no weight is specified for the latter (implying that you just use whatever weight the arm foists on you), it will happily track at something like 3.5g or even considerably less (see step 6), so we now need to devise a counterweight to allow this to happen. 3.5g is a significant figure as it's within the range of the Audio Technica moving-magnet cartridge fitted to the Sound Burger, the Coturn and many other worthy turntables, so in this respect we're already in the realms of improved quality.

[More asides: some say that a cartridge should be loaded at its maximum weight because this is the weight actually specified by its designer. The lowest possible weight is a factoid inserted for marketing purposes because people tend to be impressed by a low tracking force. Sounds very plausible to me.

Also, branded and unbranded clones or unbadged versions of the suggested replacement cartridge are now available and tend to be cheaper. Check Amazon or eBay for lookalikes or search on the Hangsu brand and/or the trips-off-the-tongue model number, which is 4NB405307. I've tested one and it seems identical in all respects.

One final interruption: don't try the following DIY counterweight design or any other on a Skywin arm (they all look very similar to this one) unless you've upgraded the cartridge. The original cartridge will be either a Chuo Denshi CZ800 or a clone of this very cheap model, requiring a very heavy tracking force (see above). This or any counterweight will just make it skip uncontrollably.

Sorry, where were we? Oh yes...]

So, shopping over, it's time to get the tools out! As with various Skywin-armed models, the Duo Deck has a small slot at the rear end of the plastic pivot cover. This has no obvious purpose on the finished unit, so I surmise it has something to do with the factory assembly process. You need to enlarge this very slightly with a small drill or reamer, to the point where you can screw the standoff directly into the resulting round hole (it'll self-tap its own receiving thread). As the standoff will be subject to a certain amount of stress after the counterweight is installed, a tiny drop of epoxy adhesive applied to the standoff thread (use a pin or toothpick) is recommended; take care not to foul the pivot mechanism with the adhesive. Ensure the standoff is installed firmly to its full thread depth and is perfectly vertical, as it'll be acting as a receiver socket for the counterweight. I wouldn't recommend using anything more substantial than a standoff (e.g. a flanged spacer) as this could move the downward force nearer to the fulcrum, thus reducing the counterweight's efficiency.

Cutting and shaping.

Now that the standoff is in place, cut a section of wire from the straight crosspiece at the bottom of the clothes hanger to make the counterweight. I found that a length of 9 3/4"/25cm produced a good initial weight (it'll be adjusted after installation), but be prepared to experiment. If you find you need more rather than less weight, given the negligible cost involved you can just grab another hanger and start again. Sliding some sleeving onto the wire will give it a neat appearance. This is best done at this point if you choose to do it, as it can be tricky after the next stage unless it's very loose. This sleeving is purely cosmetic; you could also paint or polish the wire afterwards or just leave it as it is.

You then need to curve the wire into a shape that looks very much like a curved croquet hoop. An easy way to make a good, clean curve is by forming the wire around an aerosol can; the flange on the can's top rim provides an ideal guide channel.

Finishing touches.

Next, slip about 3/4"/2cm of the heat-shrink sleeving over one end of the counterweight so that about 3/8"/1cm covers the end (strip off an equivalent amount of covering sleeving if used), leaving about the same length of excess. Shrink it into place with a heat gun or other heat source, then snip the excess off so that the sleeving is flush with the end of the wire. This is important, as any overlap or underlap will result in a less secure installation.

In practical terms the other end of the wire can stay as it is. However, adding something to give it a finished appearance doesn't hurt. I used a small plastic ferrule bought on eBay.

The tip of the wire hoop with the heat-shrink sleeving attached now needs to be inserted into the standoff so that it's installed firmly. Use an initial left-and-right twisting action not unlike using a bradawl, followed by a few screw-in rotations; you may need to lift the tonearm upwards to prevent the counterweight from tripping up on the player's casing. Do this carefully but firmly.

The standoff will cut threads into the heat-shrink sleeving that will hold it in place, so stop once the counterweight is firmly held without any vertical wobbling. It'll still rotate stiffly if you nudge it, but that's fine as this allows it to be repositioned or detached for transportation or storage if required. Overtightening will cause the threads to shred the heat-shrink sleeving (try saying that with a mouthful of gobstoppers), which you don't want, but if it does happen simply renew it and start again. Once installed, align the counterweight with the shaft of the tonearm.

You can now gradually adjust the counterweight by snipping bits off it with your wire cutters and checking the results with your stylus balance. I found that increments of 1/8" to 1/4" worked well. Bear in mind that this process will make the tonearm heavier, not lighter! You may find it useful to have a sacrificial 'punishment record' - something with a loud, cutting bass line and a wide dynamic range that would be more inclined than average to skip - to help you determine how low you can take the tracking weight.

Before adjustment the weight will probably be something like 1.5g, which for this cartridge is too light to be reliable, so you now have two options:

(i) Aim for 3.5g, which is the same weight as that required for the Audio Technica cartridge described above and therefore perfectly acceptable, or...

(ii)...see if you can get away with even less! Be aware that if the weight is too low the stylus will either skip out of the groove or coast along its upper edges without settling into it properly, which will produce distorted sound and degrade your records, so while this small challenge provides a degree of nerdy fun it requires care and patience.

If you add a ferrule or similar to the end of the counterweight, bear in mind that it will add a very small amount of weight (in this case 0.19g!) to the total, so take this into account if necessary.

Just for the record (sorry...) I went for the nerdy fun option and stopped chancing my arm (sorry again...) at 2.6g, which generally works perfectly (see the next step for a short-term plan B if required). This also happens to be the recommended tracking weight for the Ortofon Windfeld cartridge, the price of which I'll let you look up...

I leave this with you!

Once you've got your counterweight installed and adjusted you can just use the player in the usual way. You'll notice when lifting the tonearm that its reduced weight feels much more like that of the tonearm on a respectable turntable, which is pleasantly disconcerting.

If you've gone for my 2.6g weight or something like it but subsequently discover that this is too light for some records (I've found exactly one such instance to date), you can contrive an easy temporary fix by inverting the stylus guard supplied with the cartridge and sliding it it into place as shown. This will increase the weight to 3.2g, which should tame all but the worst skippers while also stlll being lighter than the recommended weight for the Audio Technica model described above.

As the tonearm has to be placed and lifted manually I recommend using the lifting device featured in another of my Instructables. You may also find the sweep arm platform I describe in yet another Instructable to be a useful accessory.

Not a further step as the project is now complete, but there are a few notes worth adding.

Most cheap turntables and record players don't merit improving, but given my very particular requirements I found it worthwhile in this case (plus the combined cost of the unit plus its replacement cartridge came in at less than UK£40/US$50, with the counterweight costing virtually nothing).

If you test the speed of the modified player with a strobe and find it's dragging as a result of using the larger platter and added weight/clamp (this didn't happen with my example) both speeds are adjustable using trimmers. These can be accessed with a precision screwdriver through the sixth hole in the bottom two rows of vent holes underneath the unit.

Clearly, this Instructable isn't a hardcore audiophile project (although I do think the counterweight has an eccentric quasi-high-end look!). The Duo Deck is a low-cost mainstream consumer product that now has legacy status and no amount of tweakery will transform this sow's ear into a silk purse. Instead, the objective here is to produce a result that's inexpensive, sonically and practically fit for its very specific purpose and much less likely to degrade records played on it, meaning they'll be fit and well when played on a proper turntable.