Wi Digital JM-WAL35 successful use so far.

[Jay Massengill]

I have recently been using the Wi Digital JM-WAL35 audio link for a number of short-range audio transmission tasks.

One of which is monitoring the headphone output of a tripod mounted camera, allowing me to step further away while using the wireless boom rather than be tied to the camera with a headphone cable.

The second use was transmitting the output from a Sound Devices MixPre (Tape Out), to the Wi receiver connected into my Canon XA10 camera audio input #1 with an XLR adapter cable.

The Sound Devices MixPre was powering a mic on the lectern to catch the introductory remarks from the host, who then took a seat in the audience. The main presenter was wearing a wireless lav which was connected to my camera's audio input #2, and they usually roam the front of the room while speaking.

Previously I had been using a mic and an H4n on the lectern to catch the intro remarks but was operating "blind" and then had to get accurate lip-sync in post. Not a big deal since I was clapping it before the host begins, but having it recorded directly into the camera gave me assurance as to the levels and didn't require syncing.

Basically the Wi Digital can turn any audio device with a monitor output into a short-range high-quality wireless mic or monitoring system. So think of converting any small recorder, camera or mixer into a short-range DIGITAL wireless audio device.

The last use I've tried was sending the output from my main mixer for a small event to a house sound system input, without having to run cables through a high-traffic area when there was no time to tape them down due to double-booking of the facility.

This also worked very well, but I did take extra time to rig the transmitter and receiver for good line-of-sight. I had a very-light-duty lightstand in my collection that allowed a perfect fit of a 48-inch wooden dowel in place of the top aluminum section and stud. This let me elevate the Wi transmitter well above head height without having any metal near it.

I haven't had any problems with this system in actual use. In testing I put lots of obstacles in the way and kept moving more distant until the sound started to break up. This testing was in a high 2.4Ghz office environment, so I felt it was reliable enough to use at the short distances of 5 to 50 feet with clear line-of-sight.

I have previously mentioned that I tested for latency and found my system had 3/4 of 1 frame delay at a 29.97 frame rate.

[Jay Massengill]

I used the Wi Digital JM-WAL35 again Friday as the wireless headphone monitor from the camera for a 2.5 hour shooting session. I wore it the whole time with Sony 7506 headphones and sound was perfect with no noise or dropouts of any kind.

[Jay Massengill]

I have now also purchased the Wi USB transmitter to go with my standard set of TX and RX.

This USB TX gives high quality stereo audio transmission from the USB output of devices like notebook computers and tablets.

My initial test with a Windows 8 laptop was problem free.

The standard receiver also has limited buttons to control media player software (Play/Pause, Track Advance/Retreat).

I've also noticed some online vendors have recently started selling the 3-piece kit with the USB TX included at the same price as the standard set of regular TX and RX used to be.

These devices have been very handy and I've had no complaints with their audio quality or reliability of signal transmission.

[Jay Massengill]

On Sunday I purchased the WI Digital JM-ALP55 Pro system to have a second complete set, and to receive the free items that were being offered.

This system has additional capabilities my original model 35 set doesn't.

Mainly, it can do bi-directional wireless USB interfacing without anything extra needed, in addition to the regular transmission of uncompressed digital 16-bit stereo 48k, converted from the analog audio input signal.

The free WI-SEMI5 in-ear monitor buds are very good! Unfortunately they are no longer being offered by the vendor I used, I'm glad I ordered when I did.

In addition, it appears the free USB-only transmitter they were also (and still are) giving away, only works with the model 35, 45 and UI systems, not with the 55 Pro. It works well with my first 35 system, but won't pair with the new 55 Pro system. And I already had one of them that I added to my original system, so I guess I just have a free spare USB Tx...

I also tracked down another model 35 system from an electronics liquidator and took a chance ordering one of the 5 they had left because the price was so low. We shall see how that turns out.

I have found these sets so useful, I won't have any trouble finding ways to employ all of them during multi-cam shoots or simple music video production.

[Greg Miller]

That looks like a very interesting family of gear!

After looking over their website, I'm a bit confused about the various combos that they offer. Perhaps I will figure that out.

Meanwhile, I have two specific questions:

1.) Does the WAL35 accept stereo mic inputs? Clearly it has a "stereo line input" mode, but that's not enough gain for mics. They say it accepts "passive guitar" which is approximately mic level, but is that a mono or stereo input mode?

2.) Is there a USB receiver that pipes the 48kHz sampled data directly into a PC, without first converting it back to analog? It seems to me that would be especially useful for high-quality audio recording, as it would eliminate the "analog hole" in the chain.

[Jay Massengill]

I agree, despite their website having a lot of information and nice photos, the kind of technical data and clearly defined model numbers and sets of Tx and Rx that we would like to see is lacking. The same has been true from most of the vendors selling these sets, mostly copying and pasting the website info.

1: In a round-about answer to your first question, I haven't tried a mic or guitar level signal with the model 35 set. See more explanation below:

The model 35 set, which is getting harder and harder to find, doesn't accept true mic-level signals at all as far as I know. It will accept guitar, instrument, line-level (all in mono or stereo) and even headphone-level signals. The LED on the front, and a small listing of modes printed on the back indicates what type of signal the Tx is set take in. It's very tolerant to hot signals, the specs say maximum input is 3Vrms!

I'm not using it for guitar transmission, only for sending stereo line-level and headphone level signals into the Tx for transmission and then use from the Rx as either line-level or headphone level outputs.
All Tx use from fixed locations, not with anyone wearing or walking around playing an instrument.

Each unit can do either level independently. For example, if you want to transmit the headphone out from a small audio recorder, then you can use the output from the Rx as either a line-level or a headphone monitor, it doesn't really matter on either end, it just works. And there are volume controls on both the Tx and Rx.

To use an XLR mic with the 35 set, I've used my Sound Devices MixPre 3.5mm tape output, and also recently broken out my two Sound Devices single XLR preamps that were in the supply cabinet, to act as a front end for this transmission system (as well as for my Tascam DR-05 recorder that lacks XLR inputs) using an XLR adapter cable from the preamp output.

On a side note, you can also use any small recorder that has built-in mics or a mic jack and attached mic, as the "front end" for these transmitting systems. You can turn a Zoom H1 into a stereo plant mic, or just have assurance through monitoring wirelessly that small recorder the groom is wearing. How often is it stated when discussing wireless versus a worn recorder, that you can't monitor the worn recorder? Now you can have both and either double-record the signal from the planted recorder or just monitor it live!

2: See below for a round-about answer to your second question:

Only the sets being sold with microphones, as well as the Pro 55 set in one limited use, can handle mic-level signals as far as I understand it currently and send that to USB.

The receiver in the Pro 55 set is actually a "transceiver" when the transmitter is connected to a USB jack. In that case, you can return a mic signal from the receiver to the transmitter and into the USB jack without a digital to analog conversion. However I haven't determined what kind of affordable lav or headworn mic would work correctly with the receiver. You use the included 3.5mm TRRS to 2x 3.5mm "headphone out and mono mic input adapter" to accomplish this connection to the Rx's I/O jack.

The Pro 55 system is designed in this case to allow both monitoring and talkback at the receiver, when using a computer connection. The instructions mention this in a Skype/VOIP scenario. I would like to experiment to see if this signal is good enough quality to actually record, but I'll have to find a mic to use first.

The Wi systems sold with mics are much more expensive, and look to be very nice, but there are no actual reviews to be found anywhere.

So to sum up, the Pro 55 system is capable of direct USB connection and sending a mic signal to the computer as described above.

The 35 system is NOT capable of direct USB data connection. The Tx and Rx can only be charged or powered by USB 5-volt power.

The USB-only Tx that is available for this system allows you to transmit audio from a computer or tablet to the receiver. I could envision that being used for guide playback in a DIY instruction video, for a dance or music video shoot, or to simply stream music to the receiver connected to an amp and speakers or wearing it on your belt with headphones. I've done both and it works very well. It's noticeably better audio quality than BlueTooth. You also have track pause/advance/reverse and mute controls on the receiver. There are no controls on the USB-only Tx, just a small USB pass-through jack and a button to initiate the pairing sequence.
The Mute and Volume controls on both the regular Tx and Rx work simultaneously. For example you can mute the Tx, then the wearer with the Rx can unmute when needed. The devices are paired and communicate these type of commands to each other.

The hard case, selection of cables included, and the AC to USB charger included, all round out these packages in a nice fashion.

[Greg Miller]

Jay,

Thanks a million for the detailed info. Yes, the mfg. info is terrible. Written for musicians, I guess.

I remember back in the day of vacuum tubes, guitar amps could be used with unbalanced mics, and unbalanced mic amps could be used with guitar pickups. I think at least the levels were similar. Not sure how today's "consumer" mics ~~ 1 kohm would work with the WAL35, but IMHO it's worth a test.

The important thing is that in "guitar" mode the input is still in stereo, and not just a mono input. Worst case, I might need to build an interface box to provide one stage of gain to boost level going into the WAL35.

Thanks again for the info ... sorry I didn't pay more attention to this back when you first posted, but I didn't have a use for this back then ... now I do.

Happy Trails!

[Jay Massengill]

You're welcome!

These sets do come with a selection of both Mono to Stereo and Stereo to Stereo input cables in both 3.5mm and 1/4-inch. Other than needing some RCA and XLR adapters to go along with the supplied cables, it's pretty easy to interface as long as you're supplying enough signal level into the model 35 set.

I'm looking forward to trying out the mic input on the 55 Receiver's I/O jack, returning to the 55 Transmitter connected to USB.

I also need to read about the other available low-cost set, the so called Ui with 30-pin Apple connector and regular USB connector devices, paired with a normal looking Rx. It appears it doesn't do anything special other than connecting to older iPhones and iPads. The receiver only has an output.

Monday I will experiment with sending my Sennheiser K6/ME64 equipped with an internal AA battery and an adapter cable into the model 35 Tx set to guitar level input. It's a hot mic, perhaps it will be enough signal? If it is enough signal, that would open up even more uses. The only thing possibly needed as a "front-end" is a hot self-powered mic. I'll report back.

Briefly, what's your anticipated use?

[Greg Miller]

I'm looking at a project to record some acoustic folk music, from solo up to perhaps three or four performers max, each possibly singing and/or playing an acoustic instrument. It's a small venue with very tight seating, I'm not allowed to have any floor mics. They are very concerned about visual impact of any mics whatsoever since they market the "acoustic" nature of the performances.

I can hang one stereo mic, and then I need to get the sound to my recorder at the rear of the audience with no wires on the floor. I have been looking at some way to gerry-rig hanging the wires from ceiling light fixtures, etc., but anything would look at least slightly tacky if not worse. If I could use a wireless link from the hanging stereo mic to my recorder, that would be ideal.

The only "gotcha" is getting the transmitter gain set correctly. Of course I can do an empty-house sound check with the musician(s) but I need to set the gain so applause or audience singing doesn't cause the system to clip. (OTOH I don't want to set the gain unreasonably low, because I will then need to crank up gain at the receiver, and noise from the receiver's analog stage could become objectionable.

I think I should record at least one show with a wired connection from mic to recorder. That will allow me to see the difference in level between typical performance and worst case (probably applause). Then if I know the voltage where the transmitter clips, I should be able to set the gain appropriately.

Of course the pro model would be best, if I could input digital directly into a PC, thereby bypassing the "analog hole" with the receiver's output stage and a recorder's input stage. Just one more situation where a wire is really the best option from a technical perspective.

[Jay Massengill]

My guess is you'd really need a good stereo preamp or recorder to accomplish this at a higher quality level than using the Wi as both a preamp and transmitter.

I've had great success transmitting line-level signals. I've done essentially nothing with the Wi using guitar level or hot mic level signals.

Until I experiment tomorrow, I won't even know if it can get enough signal from a hot mic to be useful at all.

I can say though, with the upper limit the Wi can accept when using line-level and headphone level signals, if your preamp can handle the applause, the Wi should be able to handle it too.

At the moment that would be my recommendation, use the Wi to transmit a preamped stereo signal back to a recorder, or use the Wi to transmit the monitor output from a good planted stereo recorder so you could monitor it from the back of the room.

[Greg Miller]

It will be interesting to test it and see how it performs with low level inputs. As far as a adding a mixer, all the gear will basically be hanging above the audience, between a chandelier and an eye bolt. I've tried hanging a mic and that's OK (except for the ugly dangling wires, which I hope to elminate). Adding a Wi link might not be too bad, since it's so small. Adding a mixer as a third piece of gear above the audience might start to get crazy, and I'm pretty sure the venue would object to the visual impact if nothing else.

If the Wi preamp is bad, I could conceivably build an unbalanced stereo preamp on a perf board and end up with something about the size of two film cannisters. But I'd rather not have to dedicate the time to making such an thing if I can avoid it. I wonder if anybody makes an ultraminiature battery-powered extra clean mic preamp.

For now I'll be optimistic about the transmitter's integral preamp, and not lose any sleep over it. Maybe I'll feel differently if your tests are discouraging. Or maybe I'll have to break down and buy the Pro model.

[Jay Massengill]

Today I tested a hot self-powered mic connected directly to the transmitter inputs of both the model 35 and the model 55 Pro, each set for passive guitar level.

This worked and there was plenty of level from the receiver output. Quality seemed fine but I didn't do extensive testing or recording.

This setting on the transmitter input only allows a mono signal to be sent.

To transmit stereo, the stereo line-level setting on the transmitter input must be used. That requires an external stereo preamp to use a stereo mic with these devices.

However, being able to use a hot self-powered mic directly with these transmitters does open up uses I hadn't tried yet. I had always employed a line or headphone level signal, requiring a preamp or the output of an audio device like a camera, recorder, iPhone, etc.

I don't have a mic that is directly compatible with the breakout adapter for the Pro 55 receiver, for use in transceiver mode communicating a mono mic back to the transmitter connected to USB of a computer.

This jack uses a 3.5mm TRS connector and has power, but I can't find info on the proper wiring. Perhaps it matches Sennheiser? I had read one clue that it might work with Sony 3.5mm TRS lav elements, but it didn't.

I have one more idea I need to try on Tuesday and will report back.

I could tell the signal is transmitting, with nothing plugged into the jack the noise floor in the recording software on the computer was around -60db. Pressing mic mute on the receiver would drop this to nothing.

So that holds some promise for recording wirelessly to USB if I can work out the jack details.

[Greg Miller]

Jay,

Glad to hear that the audio quality seemed OK at first glance, using a hot mic directly!

Disappointing to hear that the "guitar" setting transmits only a mono signal. I assume you still used a stereo breakout cable, and that the transmitter either takes just the left channel or else sums both channels to mono?

I'll have to look over their non-descriptive descriptive literature again. I'd swear I saw something that said the system could accommodate passive instruments with stereo pickups. By "accommodate ... stereo" I assumed they meant it would transmit the two pickups as a stereo pair.

If I can find the specific verbiage I'll copy it and post it.

[Jay Massengill]

The transmitter input jack always uses a 3.5mm TRS connector.

The supplied cables have on the opposite end from the 3.5mm TRS either: one TS 1/4-inch, two TS 1/4-in, or one TRS 3.5mm (with TRS 1/4-inch adapter) for connection to other devices.

The three input modes listed on the back of the Tx and indicated by the flashing blue portion of the multi-colored LED are worded slightly different on the model 35 and model 55 but essentially are:
Passive mono guitar preamp,
Active mono guitar or mono line-level,
or
Stereo line-level.

Today I used a Sennheiser K6/ME64 with internal AA battery, connected to a female XLR to male RCA adapter cable, connected to a female RCA to male 3.5mm TRS adapter.

Since I didn't intend to use these sets with instruments, I haven't paid much attention to their descriptions of guitar and keyboard connections. And I also hadn't thought about a passive guitar input and a hot XLR mic being roughly similar enough to use a mic directly with just an adapter rather than a preamp and line-level. Thanks for the suggestion!

[Greg Miller]

Jay,

I'm sorry my memory of guitar pickups is rather rusty ... that takes me back about 40 years in my checkered past. Seems to me they were similar to hi-z mics (we're talking a range of perhaps 10 kohms to 50 kohms). If that's accurate, then you might get even more level (and a better S/N) if you use an in-line mic impedance matching transformer, with the lo-z side fed from the mic, and the hi-z side feeding the transmitter. I apologize that I don't recall this with more specific detail.

Meanwhile, just to clarify what you tried ... Your mic was eventually adapted down to a single RCA? You had some sort of cable feeding into the transmitter, with a 3.5mm TRS on the transmitter end? Was that adapter cable a breakout cable, with two RCAs on the other end (one to tip, one to ring)?

And then assuming all the above is correct, if you tried the mic separately on each of the RCAs on the breakout cable, what came out of the receiver? Identical mic audio on both receiver channels?

My order supposedly has been shipped, so holding my breath here ... praying for the right mix of hardware, and hopefully the desired functionality.