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[Keith Broughton]

 behaving exactly as one would expect with too many cascaded active components.

Jason Glass
http://cleanwirelessaudio.com

That meaning the active stages can contribute to intermod artifacts?
So the next question is , would a passive initial split to the 3 active splitters  be better even though there is a bit of loss in signal strength?

[Jason Glass]

That meaning the active stages can contribute to intermod artifacts?

Yes. Not only intermodulation, but also received noise,  internally generated noise, harmonics, and spurious signals being amplified at each stage.

Jason Glass
http://cleanwirelessaudio.com

[Jason Glass]

would a passive initial split to the 3 active splitters  be better even though there is a bit of loss in signal strength?

I did that very thing in my Tonight Show rig. You just need to make sure that you choose an antenna with enough gain to overcome the total path loss, including splitter loss, to receive a satisfactory signal level at the receivers.

Jason Glass
http://cleanwirelessaudio.com

[Keith Broughton]

I did that very thing in my Tonight Show rig. You just need to make sure that you choose an antenna with enough gain to overcome the total path loss, including splitter loss, to receive a satisfactory signal level at the receivers.

Jason Glass
http://cleanwirelessaudio.com

Thanks for the info Jason

[Russell Ault]

No notch filters, but two of the expensive options (Axient AXT630 and Sennheiser ASA3000) can do 60Mhz bandpass filters that cover their respective transmitter frequency ranges.
Front panel switch on the Axient, swap-able hardware modules on the Sennheiser. The Axient also has an unfiltered out for cascading.
Good for noisy environments.

Does anyone know, offhand, what RF processing actually goes on "under the hood" in, say, the ASA 1 or the UA844SWB/UA845SWB? Presumably its something like "wide bandpass filter -> amplifier -> splitter" (with a DC injector at the end if you're Sennheiser), but the manuals for those items mention almost nothing about, for example, what filtering is actually happening (the Sennheiser-provided block diagram mentions nothing about filtering at all).

Thanks!

-Russ

[Lyle Williams]

I'd expect that filter/amp/split/inject sequence to be the case.  My splitter is built from minicircuits parts.  Does anyone have an ASA1 and a VNA to see what filtering occurs?

[Russell Ault]

I'd expect that filter/amp/split/inject sequence to be the case.  My splitter is built from minicircuits parts.  Does anyone have an ASA1 and a VNA to see what filtering occurs?

If you don't mind sharing, which Mini-Circuits parts?

Thanks!

-Russ

[Lyle Williams]

Passive 2-way is ZAPD-21, like http://www.akg.com/pro/p/zapd-21 but mine have SMA connectors instead of BNC.

Active 4-way is 2dB attenuator followed by BLP-750 lowpass followed by ZFL-1000 amp followed by ZFSC-4-1 splitter.

Obviously two chains of the above items for diversity RX.

When buying second hand you really just hunt around for suitable parts at suitable prices.  A lot of this used gear seems to come out of Israel, for reasons that escape me.

[Lyle Williams]

For some price context (in my neck of the woods, Australia) 2x ZAPD-21 (used) is $50, a ASA1 is $800.

[Jason Glass]

Passive 2-way is ZAPD-21, like http://www.akg.com/pro/p/zapd-21 but mine have SMA connectors instead of BNC.

Active 4-way is 2dB attenuator followed by BLP-750 lowpass followed by ZFL-1000 amp followed by ZFSC-4-1 splitter.

Obviously two chains of the above items for diversity RX.

When buying second hand you really just hunt around for suitable parts at suitable prices.  A lot of this used gear seems to come out of Israel, for reasons that escape me.

Hi Lyle,

Your Mini-Circuits DA is similar to my 4x4 multi zone DA.  Its input is a ZFSC-4-1 (surface mount on an old Vega PCB) which loops out of my chassis after combining via BNC for inserting external filters and attenuators > ZFL-1000VH > ZFSC-4-1 (duplicate of input PCB) > BNC outputs.  It works well for zoned intercom RX, and it's versatile because I can choose appropriate filters for the desired freq range before the signal path enters the amp.  I usually insert rotary stepped attenuators before the inputs to adjust each zone's overlap.

Just like yours, many of my parts are surplus eBay finds.  Having the flexibility of component parts at a fraction of the cost of dedicated assemblies can be a huge advantage.

BTW, your your DA setup is very close to what was inside 1990's Vega DA's.  Here in the States, the inserted attenuator was 6dB, and the pre filter was a 450 MHz high pass in their UHF units.  When you can find them on eBay for cheap, they are a goldmine of useful components.

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