Dual 721 turntable - opinions/advice?


I just picked up a Dual 721 for under $20. Seems to run fine. Looking at the strobe, it looks like it is maintaining speed. It has a "supposedly" new AT120E cartridge. Maybe new 20 years ago? Dust cover is thrashed.

I thought I might have someone put new RCA cables on it, a little oil on the bearings, and put my Sumiko Pearl cartridge on it.

• Any advice? Thoughts?
• How does this TT compare to others?
• How does this compare to my Akai AP-Q80 direct drive TT?
• Any ideas where to get a dust cover in decent condition?

Thanks,
Craig
craig_c
Ekobesky,
Actually, I paid $10.

The dustcover is cracked all the way across the middle, side to side. And I know cosmetics are not critical to function, It would be nice if it looked better.

I don't understand "high compliance" or why the brand new Sumiko wouldn't be a good fit. I'd appreciate whatever you can do to educate me on this topic of matching tone-arms with cartridges. I was worried that the Shure or AT would be too bright for me in the highs. What is a "ULM" arm?

Craig
Phono cartridges have suspensions, just as cars do. If you were to put a very stuff suspension on a very lightweight car, the ride quality would be stiff and unbearable. Conversely, if you put a very compliant suspension on a heavy car, it would be squishy and prone to bottoming out.

The same is true for phono cartridges. The Dual ULM arm is Ultra Low Mass -- very lightweight. So, you need a cartridge that has a very compliant suspension so that is can be loaded properly. A low compliance cartridge will be too stiff, and it will introduce audible resonances.

Today, most tonearms are medium to high mass, and most cartridges are accordingly designed with stiffer suspensions. The Sumiko is best matched with medium mass arms. The Dual arm will likely not have enough mass to properly load the suspension...the cartridge will just sort of ride on top of the grooves. At best, it could sound like crap. At worst, it could possibly damage your LPs. Now, you could add extra weight to the headshell...but that defeats the purpose of the ULM concept.

Therefore, it would be best to stick with one of the cartridges I recommended. If you have a cheap phono stage, the Ortofon OM10 would be an appropriate solution as would the Shure M97xE. If you have a decent phono stage, then I would recommend the Ortofon 2M Red or a new stylus for the Audio-Technica. And if you have a better-than-average phono stage, it would not be unreasonable to suggest the Ortofon 2M Blue. I'm using one now on a Dual CS-505-3 and it sounds great.

In any event, the Audio-Technica AT120E is a more resolving cartridge with a finer stylus unit than the Sumiko so regardless of compatibility issues, replacing the AT120E stylus would be the cheapest path.

As far as the dustcover....it keeps the dust off, right? It's best to remove it anyway when listening. If you leave it up, it acts as a "sail" for resonances. If you put it down, it can allow static electricity to build up. Remove the hinges and rest it on top of the table so you can easily remove it during use. If you think of it as a dustcover rather than an aesthetic part of the turntable's design, then you can buy virtually any replacement that rests comfortably on top.

I really think you made a fine buy there. The fact that your Dual is still functioning as intended 30 years later speaks to its enduring quality. Like an old car, you have to put a little bit more effort into replacing parts (in this case, the cartridge) but assuming you use properly suitable replacements, there's no reason why the Dual can't sound good even by modern standards.
Thanks, very clear information.
Since the owner claimed that it "had a new needle", how can I evaluate the condition of the stylus?

My phono stage is a Proton 1100 preamp. It likely doesn't stack up against preamps in the multi-hundred dollar range, but my understanding is that the innards are essentially identical to a NAK of the same class. So, from what I gather, not a bad little pre.

Now what to do with the Sumiko cartridge.

Craig
I misspoke. My Proton 1100 is pretty much identical to a NAD 1130.

Is there a thread here to help a newbie evaluate the condition of a stylus?

Craig
Just replace it. A new stylus is about $60 for the Audio-Technica. Cheap insurance. There is really no way -- aside from gross mistracking -- for someone without a microscope and experience to effectively evaluate the condition of a stylus. Besides, even if the stylus is fine, the suspension bits may be dried up and damaged. A new stylus unit insures against both possibilities.

Your Proton has a pretty good phono stage. Like NAD stuff, it can sound a bit 'dark.' So, provided your speakers aren't overly bright, I would go with the Audio-Technica AT120E you already have or the Ortofon 2M. Both have detailed enough treble to counteract the preamp's tendencies.