Lamplighter

Hi Chris You don't need to worry unduly about matching to the 100 v line to identify your circuits. A 100 to 200 w amplifier at 8 ohms will easily give you enough level without a matching transformer. If it is easier then a 10 w amp with a speaker transformer in reverse will suffice. I would tend to use pink noise as it is easier to locate a speaker where there might be more than one in earshot. Music works well but you always get a quiet bit at the wrong time. Brian

Does anyone have a Trantec S5.5 receiver service manual ? Thanks Brian

I would rewire with the two pots joined in series, that would give 0 to 100% attenuation

The Sennheiser quick guide to XSW2 shows a minimum of 5 metres between Transmitter and Receiver. The other consideration is to run an intermodulation check across all channels in use.

A short term solution would be to cover the boom and capsule with heatshrink. RS do a darkish brown. The other solution which has been mentioned previously is to paint the boom and mic.

Hi Steve That sounds as if the memory battery needs replacing. Brian

Update Eventually found this after a bit of searching. https://www.sennheiser-sites.com/responsive-manuals/XSW_IEM/EN/index.html#page/XSW_IEM/XSW_IEM_02_Instructions_EN.3.13.html Simple when you know what is there.

Has anyone worked out how to remove the belt clip from Sennheiser XSW 2 belt-pack? First appearances suggest that the pack may need dismantling to release it. I always use them in a pouch so the clip is redundant. Brian

The later Yamaha models use "back" or " previous" to return to the previous scene. I'm not sure if that works for AH.

My 2018 - 2019 paper catalogue is still current, though quite a few items have disappeared or been replaced. It still makes a good starting point when looking for most things. Brian

Richard You can choose any 3 from 173.8, 174.1, 174.5 and 174.8 and add 175.0 for intermod free operation. External noise is a separate problem which is not so easily overcome. I haven't looked at the new frequencies as my S3500 kit hasn't got them loaded. A quick look says that they are a disaster waiting to happen with 200KHz spacing all the way. The old 5 channels give 300, 400, 300, 200 KHz spacings so you only require to loose 1 channel from the first 4 to be intermod free. All 5 of the old channels are intermod free of 3rd and 5th order products but only for 2 transmitters in close proximity The 4 channel scenario works for 3 transmitters, and is generally considered best practice. Brian

CPC MF12 range £1.32 for a pack of 50 resistors. 10k = RE04068 2k2 = RE04074

And now we are on the same wavelength (pun intended)

Ray We are referring to the circulator in the transmitter aerial path, this reduces the level of other transmitted signals getting into the output stage and mixing with that transmitter frequency. The reduction in spurious output is pretty dramatic, it can be as much as 60 dB if well engineered. The first 30 dB is directly due to the isolation given by the circulator the rest by the reduction of mixing products. As previously mentioned the main source of intermod problems in radiomic systems is interaction between the transmitters.

That makes sense, fitting circulators in the transmitters will drastically reduce the intermods between them, the major source of the problem. It is interesting that they have developed them to be small enough to do this.

Possibly referring to IEM transmitters?

Hi Simon Improving the receiver front end is always a good thing, however it cannot sort out the intermods caused by linear frequency spacing in analogue systems (assuming that means that each channel is spaced the same from its adjacent channel). This only works in the digital realm. In the world of radio microphones most intermods are transmitter related, so intermods generated by equally spaced transmitters will still fall in the centre of the receiver passband. Improved receiver filtering will certainly assist with adjacent channel problems and possibly allow more channels in a given spectrum. Currently I am only purchasing 2 channels of 1.8 GHz equipment, until I have gained enough experience to see if larger numbers are viable. The EW-D range looks interesting, but are currently beyond any foreseen budget. Brian

The official answer pre purchase "usually the available channels in a single back are the channels with the less interferences. Unfortunately one unit was damaged on arrival, the other works. They have actually got 16 banks of 12 channels. I checked bank 1. 1795.650 1796.050 1796.750 1797.250 1797.650 1799.000 1799.400 1775.700 1786.100 1786.950 1787.450 1788.300 Life is too short to read the remaining 15 banks! looking at the separation between channels we have 400, 700, 500, 400, 1350, 400, miss the gap between channels 7 and 8, then 400, 850, 500, 850 all in KHz, then 7. 5 MHz between channels 12 and 1. so a very strange combination. Taking the first 7 channels we have very obvious 3 transmitter 3rd order intermods. However taking all 6 even numbered channels we have good spacing and free from 3rd order intermods. I set a transmitter to channel 1 and receiver to channel 2, the minimum spacing in the bank and even with Rx and Tx aerials touching and Tx audio driven did not get breakthrough on the receiver. A crude test but seems to indicate a reasonable adjacent channel performance. The accompanying booklet gives the deviation as +/- 55KHz. It is frustrating that all my test gear only goes to 1500 MHz so I am not able to do any precise measurements. I cannot fathom the logic of the preprogrammed channel/ banks and the 6 channel recommended limit. I can easily arrange 12 channels in the available bandwidth with a minimum separation of 400KHz and 100Khz deviation, clear of 3rd order 3 transmitter intermods. It's as though there is a hidden trap somewhere. It will be some time before I can fully explore the practical limitations on some real world site, so anyone actually used 1.8 G in the real world? Brian

Hi Dave I have a couple of the T-Bone 1.8 GHz units on order. They claim 6 channels in the band out of 16 preset frequencies. When they arrive I will put them through their paces and report back.

Hi Dave To clarify, the group already has maxed out on channel 38s, 64/65 and 70, largely due to using older, fixed channel systems. There are plans afoot to replace this but funds are currently very limited due to investments in building infrastructure. I am looking for a cost effective way to increase their channel count whilst not blocking the future improvements in the existing bands. 1.8 GHz seems to meet this requirement. Sadly the current price of the XSW 2 seems to be around £400 per channel. Brian

Hi Matt The LS 9 supports 300 scenes , all selectable using Midi. Attached is a list of required program change values. Above scene 127 change to bank 2 then bank 3. I don't use Q-lab but it should be able to cope. Brian LS9-Midi.docx

Has anyone used any of the cheaper offerings in the 1.8 GHz band. I am looking for any practical experiences. I am trying to sort out a local theatre group with some additional channels and 1.8 GHz seemed a possible solution. I have found one model with 16 channels and a statement that up to 6 simultaneous channels can be used. I enquired of the supplier what were the 16 channels, what was the minimum frequency separation and also maximum Tx deviation. This seemed to me the basic information required to have 6 channels co-exist. The reply was "usually the available channels in a single back are the channels with the less interferences" so no help there. The second unit claims 8 banks of 12 channels so I assumed I would be ok to use 12 channels together. I enquired if this was so, no it's a maximum of 4 channels. The same questions as before Frequency separation and deviation gave me "400 Minimum" and then " Please understand, I just can offer you official Data from us. U518 // 1785 – 1800 MHz // four systems can be used simultaneously " To be clear I wasn't expecting miracles at sub £300 channel but 4 channels in a 19 MHz bandwidth seems ridiculous when quoting a minimum separation. I did a quick calculation and easily fitted 12 intermod free channels in the band using 100 kHz as the TX deviation. Any real world observations welcome.

Phil you could try these https://cpc.farnell.com/pro-signal/mp33750/microphone-lavalier-beige/dp/MP33750?ost=mp33750 though you would need to change the connector. Or these if you have some slack on the back order date https://cpc.farnell.com/stageline/ecm-501l-sk/microphone-mini-xlr/dp/MP33611?ost=mp33611 If you need more headroom then try these https://cpc.farnell.com/jts/cm-201if/microphone-omni-lavalier-beige/dp/MP33730 though you would need to change the connector and the stock situation is not so good. I have used the first type for both hairline and upper cheek mounts without problems. The cable is not the best but for the price ?? Brian

I would be looking for a 50% trade discount. Still expensive but more realistic. Brian

Whoops The values shown actually give around 15dB attenuation. It works well for me, originally a quick fix with available bits. If you desire 10dB then change the 10k resistor to 4k7. Brian