James main logo black


10" Subterranean Subwoofer (70V)

Technology header click

With the ST10-70 subterranean subwoofer, outdoor entertainment has never been so complete. Having mastered the mix of excellence in design, technology, and superior sound this direct burial subwoofer is built to preform and astound. Designed with motion in mind James outdoor systems provide consistent sound levels in multiple stereo listening areas: by the pool, next to guests mingling at the bbq or surrounding tennis courts. James’ subterranean subwoofer’s direct burial, 10” compression bandpass design creates an earthshaking performance. External hooded port, Aircraft aluminum enclosure and marine grade hardware allow for protection in extreme weather conditions.

Frequency Response

24-140Hz +/-3dB

Nominal Impedance

70 volt


88dB 2.83V/1m



70V Power

200W Toroidal Transformer

Recommended Amplifier



(1) 10" (254mm) Aluminum


Aircraft Marine Grade Aluminum


Black buried enclosure, Standard Verde exposed port (Custom finishes available for a nominal upcharge)


11.125 in (282.57 mm)


18.5 in (469.90 mm)


14.375 in (365.12 mm)

Product Documents

Related Documents

Click photo for download image options


ST10-70 - Available downloads

Title: 101ST70 front

Size Resolution (Right-click: Save link as...)
83.57 KB 900x900 101ST.jpg
At sub install art

ST10-70 - Available downloads

Title: ST series installation

At sub install art
Size Resolution (Right-click: Save link as...)
435.31 KB 1224x900 AT-sub-install-art.jpg
70v test equipment 2

ST10-70 - Available downloads

Title: 70V testing options

70v test equipment 2
Size Resolution (Right-click: Save link as...)
116.69 KB 960x720 70V_test_equipment_2.jpg

James Loudspeaker Helps Expand Maverick Integration's Outdoor Audio Business

Dennis Jaques of Maverick Integration in Nashua, N.H., explains how the 70V Landscape Series line of speakers from James Loudspeaker enabled the company to expand its outdoor audio business.

Category FAQs

Traditional 70V speakers will have a transformer as the load.  Because tranformers react differently to DC and AC signals, an ohm meter reading will measure the DC resistance (DCR) of the transformer and will not provide any info on the actual rating of the speaker when passing audio, and might even read near 4 or 8 ohms which might indicate incorrectly, it is a 4 or 8 ohm speaker.  In the audio band, the impedance presented by the transformer will be much greater than the DC resistance.

Unlike traditional 70V speakers, James Landscape sats, the AT series, also feature an additional low frequency roll off via a built-in network to protect the speaker as well as allow running the sats on the same line as a subwoofer.  These features block all DC signals, making an ohm-meter useless for testing as it will measure "open circuit" on both 4 ohm and 70V speakers.

So the speaker must be measured with an 70V IMPEDANCE METER which characterises the IMPEDANCE at 1kHz, not at DC RESISTANCE.  Examples follow the table.

Below is a table which shows impedance and DCR reading to be expected on AT sats and ST subwoofers.

Table1 - AT and ST loudspeaker impedance data
32AT4 9 ohms open  
32AT70 300 ohms open  
42AT4 7 ohms open  
42AT70 150 ohms open  
62AT4 11 ohms open  
62AT70 105 ohms open  
81ST4     Bi-amp only
81ST70     Bi-amp only
81ST70-X     Crossover for fullrange systems
101ST4     Bi-amp only
101ST70     Bi-amp only
101ST70-X     Crossover for fullrange systems
121ST4     Bi-amp only
121ST70     Bi-amp only
121ST70-X     Crossover for fullrange systems
151ST4     Bi-amp only

Bi-amp only

Fig 1 shows three examples of 70V impedance measurement tools; the TOA  ZM-104A, the TENMA 72-6948, and the Dayton Audio DATS2 speaker testing software.  The two impedance meters test at only 1kHz which can give you readings which may appear out of spec, where as DATS2 gives you a full 20Hz to 20kHz impedance curve so you see all the data and read the frequency of interest.  DATS2 is our favorite as it works with a laptop, is small and also the cheapest of the options.

Fig 1 - 70V mesurement tools

To show the versatility of DATS2, Fig 2 below shows a DATS2 curve run on a 32AT70 loudspeaker.  To get the same reading as an impedance meter, you would read the impedance at 1kHz o the graph, but as you can see, there is a wealth of information in the curve.  In this example, DATS2 is calling out about 281 ohms at 1 kHz, close to the 300 the impedance meters will read.

For those with an understanding of the math, the power at 1kHz will be 5000/281 = 18W.  The lowest impedance is around 450 Hz at about 190 ohms, giving 5000/190 = 26W.  So as you can see, even though the transformer is rated at 30W at 4 ohms, when used with a speaker the real power is quite different. 

When this same transformer is loaded with a 4 ohm resisitive load, the reading is 140 ohms which is 5000/140 =3 5W, typical for a 30W rating.  So all contant voltage transformers, regardless if they are 25V, 70V or 100V, only have a nomial power rating at a nominal load impedance - results will vary in use!


Fig 2 - DATS2 curve of 32AT70

Welcome! Admin Login
Ph: +1.775.461.7500 | Fx: +1.775.461.7599
Ā© Copyright 2022 James Loudspeaker LLC