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Using 4 pin XLR balanced output vs. 1/4" single-ended of Topping L70 for low impedance


Addicted to Fun and Learning
Aug 5, 2021
So I've got an L70 which I purchased along with my E70 Velvet. Awesome

Now, because "why not", I've decided that in addition to headphone duty, driving my passive studio monitors would also be in the L70's purview. Don't worry, they're not huge and far away in a massive room - they're currently set up in a 10x8 foot space with an 8 foot ceiling, and some treatment on side walls/behind listening position. To connect them, I made myself a solid copper, gold plated, quarter inch adapter -> 14 gauge copper wire. The copper wire is short, so I stuff the strands of its ends into the interestingly shaped (semi-circle) hollow ends of my banana plugs attached to 8 feet of 8VS wire, for a surprisingly solid connection. It's so solid you can even move things around and there's no crackling! The connection could obviously be better, but I'm convinced it's satisfactory - the balance and imaging are phenomenal.

OK, so, I was looking at the product page for the L70 and came across a bigger version of this chart:

As well as this:

Fun fact: I also have the L30 II, and it has also been connected to these speakers via the 1/4" adapter I made.

Fun fact 2: The above image isn't AI's imaginings of the specifications of what a single-ended balanced L70 would measure (if it could exist...)
It's the L30 II's specification!

I take issue with these specifications, at least the L30 II's, because the L70 can definitely drive my speakers louder than the L30 II, and not just slightly. I didn't go so far as to measure SPL before clipping, but I'm pretty good at guessing, and I guess it could drive them +2.5 to +3.0dB.

I did some math with their other numbers, too, and it came out interesting:

I VIR'd 3500mW and 16 ohms. Answer? 0.46A !
6000mW with 16 ohms? 0.61A !!!

Granted, the current rating is for peak and the power rating is for (I believe) 0.1%THD, which, in the L30 II/L70's cases, due to the extremely clean nature of their outputs, is a little way's in to clipping, but not a lot.

Maybe the "peak" rating by definition is exactly double continuous? That can't be right though - it's peak power that's double continuous power, not double current (because voltage doesn't remain the same, which it would have to if both power and current doubled --- the resistance isn't changing, so)

Anyway, this situation is confusing to me because Topping seems to be all about measurements. Well, not all. But looking at their products, they do appear to strive for them to be as high as possible). I can't think of a single time I saw a review of a Topping device - one here or l7, or at any other place that takes [proper] measurements, and the results didn't closely match what Topping themselves claimed. These two, Mr. L30 II and L70, rated the same, and not performing the same... it just kind of flies in the face

I was wondering if/how the performance of my L70 might change if I switched from the 1/4" adapter I made, to balanced. 4 pin XLR is a VERY oddly sized connector, and I haven't been able to find one nearby or in the rainforest (Amazon). If I'm to go through all the effort of procuring one, I'd like to be in the position to benefit from it afterwards (lol obviously... said everywhere by everyone who ever purchased anything...). The speakers to be driven are rated 8 ohms nominally. The low/mid frequencies are done by an 8 ohm rated mid-woofer in a sealed, 20L cabinet. The tweeter itself is 6 ohms, but being 6.5dB/W more efficient than the woofer, it's padded down. In the bass, the lowest impedance is right around 6.2 ohms and with the sealed cabinet, there's minimal junk getting thrown back at the L70 out of phase. At the higher frequencies (approaching and at/above 2.1kHz), impedance is probably quite a bit higher than the 6.2 ohm minimum of the woofer (from the 6.5dB attenuation).

Although speakers are a more difficult load than most headphones, these speakers aren't most speakers - they're easier. They're sealed, 2 way, 3rd order Butterworth crossovers, air coils, etc. And the L70's output impedance is low enough, and remains low enough, after the required connections are made to the speaker (resultant damping factor is ~35, or "pre-e good!")

What should I expect? Should I find one of those elusive, 4 pin XLR ends? Or should I leave it single-ended?
(pun intended)
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