* Super AA exchange *
(alias ALK Jr. == alias SUPER X)
Here is a very cost effective way to improve the sound of your Klipsch Heritage speaker.
If you have a Klipschorn, Belle Klipsch or La Scala that has the "AA balancing network" it can be not just restored with new capacitors but actually upgraded to a far superior design with a few part changes and additions. Simply return your old AA network and I will quickly return a refurbished and upgraded "Super AA" to you!
There is no secret here. All the parts shown in green on the drawing below will change value. Those in red will be added. You could do this yourself if you feel up to the job. You will need to get the parts yourself. I do not supply them. If not, ALK is ready to do it for you!
** The Super AA upgrade **
What kind of improvement can I expect?
You will hear improvement in every aspect of the sound. The Super AA is actually the CSW network with one less part in the squawker filter (it's 1st order rather then 2nd). There is also a fixed 3 dB resistive "L-Pad" attenuator added to the tweeter filter to bring the level back to the level required by the K77 tweeter. The CSW network uses an adjustable pad.
* The woofer filter is unchanged. The single 2.5 mHy inductor of the AA is reused. You might perceive a slight increase in bass caused by the reduced level through the midrange. This might happen due to a natural tendency to turn up the volume a bit to compensate.
* Measured performance of the stock Klipsch AA and the Super AA squawker filter. The modification adds a true bandpass rather then depending on the upper frequency limit of the K55 driver to form the crossover to the tweeter. The squawker level is reduced slightly (about 2 dB) to reduce the harshness associated with the K400 squawker horn.
* Measured performance of the stock Klipsch AA and the Super AA tweeter filter. The stock AA tweeter filter has a very rough response and goes too low. The new tweeter filter creates a true crossover at 6 KHz. The flatter response will result in a bit more highs in the range of 7 - 15 KHz.
In English, all this should translate to a bit more bass and a softer, crisper sound.
* Measured impedance seen by your amplifier using the stock Klipsch AA and the Super AA. As you can see from the plot below, the stock AA network presents a load to your amplifier that varies from less than 10 Ohms to over 30 Ohms. Note that the peak impedance is right in the middle of the squawker range where our hearing is most sensitive. With the Super AA network, your amplifier will now see a true 8 ohm load. This is a significant advantage if you are using a small single-ended tube (SET) amplifier.
How about the price?
The price is tentatively set at $99.00 for a set of two plus your old set of AA networks. This includes all new capacitors (Audyn of Germany) and small inductors (Solen hepta-Litz). The base board, connection block, T2A transformer, zener tweeter protector and large woofer inductor will all be retained. The cost of any of those parts that must be replaced will be additional.
I expect to have a set ready to ship at all times on and exchange basis, but they may not be as "pretty" as the ones you have. Actual turn-around time will usually be time spent in shipping unless I happen to be out of parts.
- At this point, no other Klipsch networks will be considered for this modification. Only the "AA" network.
- Some AA networks have been the victims of unfortunate circumstances turning them into total rust piles. ALK reserves the right to reject these as upgrade candidates. Return shipping cost will be charged to the customer.
Some of the things that will DISqualify a set for the upgrade are:
- Puddles of oil on the board from leaking caps.
- Missing zener diode tweeter protectors.
- Some parts that need to be replaced will be replaced by used and tested parts from salvaged networks. The price charged for these will be adjusted on the basis of their asthetic quality. Be assured that no questionable parts will be reused!
- Blown 1N3996 zener diodes will be replaced with new ones for $10.00 each.
- No variations will be considered. This network is what it is!
- Shipping note: When you return your old AA make sure all the screws on the connection block are down tight. They tend to unscrew themselves in shipping and vanish!