Using Airport Express to extend wi-fi range

Is your AirPort Extreme Base Station (AEBS) the newer 802.11n or older (dome-shaped) 802.11b/g version? How to configure these base stations to extend the wireless range is different based on their versions.

Here are the basic steps ...
o If practical, place the base stations in near proximity to each other during the setup phase. Once done, move them to their desired locations.
o Open AirPort Utility and select the base station that will connect to the Internet.
o Choose Manual Setup from the Base Station menu, or double-click the base station to open the configuration in a separate window. Enter the base station password if necessary.
o Click AirPort in the toolbar, and then click Wireless.
o Choose “Create a wireless network” from the Wireless Mode pop-up menu, and then select the “Allow this network to be extended” checkbox.
o Next, select the base station that will extend this network, and choose Manual Setup from the Base Station menu, or double-click the base station to open its configuration in a separate window. Enter the base station password if necessary.
o Choose “Extend a wireless network” from the Wireless Mode pop-up menu, and then choose the network you want to extend from the Network Name pop-up menu.
o Enter the base station network and base station password is necessary.
o Click Update to update the base station with new network settings.
(ref: Page 46 of " Designing AirPort Networks Using AirPort Utility.)

Is the AirPort Express Base Station (AX) the newer 802.11n or older 802.11b/g version?

The 802.11n version came out in March 2008, so it sounds like you have the earlier model. To double-check the 802.11n is model# A1264; the 802.11b/g is model# A1084.

Since you will have a "mix" of AirPorts, you will not be able to take advantage of the "extend a network" feature of the newer AirPorts, instead you will need to configure these base stations for a Wireless Distribution System (WDS).

AEBSn - WDS Setup
(Note: To facilitate the WDS set up, place the base stations within near proximity of each other during the set up phase, and then relocate them to their desired locations when complete. Also, jot down the AirPort IDs (MAC addresses) for each of the base stations to be used in the WDS. The AirPort ID and is printed on the label on the bottom/side of the base station.)

Main Base Station Setup - AEBSn
o Click the AirPort status menu in the menu bar and choose the wireless network created by the AEBSn.
o Open AirPort Utility (located in the Utilities folder in the Applications folder on a Macintosh computer, or in Start > All Programs > AirPort on a computer using Windows).
o Select the AEBSn, and choose Manual Setup from the Base
Station menu, or double-click the base station to open the configuration in a separate window.
o Enter the base station password if necessary. If the base station is using the
default password of public, you will not be prompted for a password.
o Click Wireless in the toolbar, and then choose “Participate in a WDS network” from the Wireless Mode pop-up menu.
o Click WDS and then choose “WDS main” from the WDS Mode pop-up menu.
o Select the “Allow wireless clients” checkbox if you want client computer to connect to this base station.
o Click the Add "+" button and enter the AirPort ID of the AX.
o Click Update to send the new settings to the base stations in the WDS.

Remote Base Station Setup - AX
o Click the AirPort status menu in the menu bar and choose the wireless network created by the AX.
o Open AirPort Utility.
o Select the AX, and choose Manual Setup from the Base Station menu.
o Enter the base station password, if necessary. If the base station is using the default password of public, you will not be prompted for a password.
o Enter the same network password as the AEBSn, if necessary.
o Click AirPort in the toolbar and click Wireless. Choose “Participate in a WDS network” from the Wireless Mode pop-up menu, and choose the same channel as the AEBSn from the Channel pop-up menu.
o Click WDS and choose “WDS remote” from the pop-up menu.
o Enter the AirPort ID of the AEBSn in the WDS Main field.
o Click Update to transfer the settings to the base station.

(ref: Pages 42-46 of " Designing AirPort Networks.)

The model A1084 AX will be returned to its old duty which was hooked up to my stereo set as an iTune "receiver". In this case, do I still have a mix Airport setup?

Yes, but only in the sense of connecting any 802.11b/g wireless client to your 802.11n network will reduce the overall bandwidth of the 802.11n network, but not necessarily down to the max. bandwidth of that non-"n" client. The bottom-line for performance? If you want 300+ Mbps bandwidth all of your wireless devices must support (& be operating) in the "802.11n only (5 GHz)" radio mode.

If I set up the gExpress to stream iTune to my stereo but power it down for the time period that I don't play the songs from iTune, would the new nExpress in the guest room be operating at the higher speed or not?

Yes ... but remember if any other 802.11b/g wireless client (not just the AX) connects to your 802.11n network, it will affect the overall bandwidth performance of that network.

In other words, would setting up the gExpress to be used with iTune degrade the transmission speed between the nExtreme and the nExpress, even when the gExpress is off line?

No. The AX would not affect the 802.11n wireless network when unplugged. It would also not impact the 802.11n network if it was operating its own wireless network ... especially if you are running the 802.11n network in the 5 GHz radio band. So, theoretically, you could leave it plugged in, and then, "switch" networks when you want to stream iTunes.

Even if you were running 802.11b (11 Mbps) your WLAN will be many times faster than your current Internet service. Where you will really notice the difference is between wireless clients on the wireless network ... especially for things like transferring files between them.