BillyBrack

Amagno: welcome to the Klipsch Community. I note that you have commented on the review I wrote for Amazon as well as the stuff I have written here. I have been running the system I have described here and in the Amazon review for a little more than two years. The short answer is the amplifier has plenty of power to drive these speakers. I say this unreservedly based on at least eight hour a week of playing music. When I was contemplating putting together my system, the price seemed daunting, but it has turned out to have been a great purchase.

Yes. There is no TV and far too much furniture. In this room we have a fireplace and a dining room we use in the winter. I read a lot during the day and mostly listen to classical guitar music while reading. Even worse this is California. Ten months a year we live outside. I leave the door open in order to hear music when sitting outside.

Word got out that I was interested in designing a system based around RF-7 floor standing speakers. I found out that a friend had a set stored in his garage. He bought an elaborate home theatre system when he was a bachelor. Does anybody remember DLP TV sets? They were very large! Today DLP is used in projection systems for movie theatres, but in the home they have been replaced by flat screen TVs. His system consisted of a pair of the original RF-7 floor standing speakers and a massive center channel (I don’t have room for it) and a 12” subwoofer. When he got married, the choice was the wife or the AV system. The TV went, but he kept the Klipsch in the garage. My intent was to buy a pair of RF-7 II floor standing speakers, but I now have on loan a pair of original RF-7 and a 12” Klipsch subwoofer of unknown lineage (I couldn’t find it in the “discontinued items” section.). The system came with a Denon AVR-2802 amplifier. This supports 5.1 channels at 80 watts per channel (at 8 Ohms) and could run my RF-7s louder than I wanted to play them. The subwoofer has a 350 watt amplifier. I got rid of the Denon and replaced it with the Teac AI-501DA and a Teac DS-H01 docking station. All of my music is stored on a Windows 8.1 system. I bought the cheapest Dell I could find that had a CD drive and a terabyte disk. This is my audio repository. I don’t own an iAnything, but my guests have iPhones and iPods, and the docking station allows them to play their music when visiting. The nice thing about the docking station is that it supports digital output. You can take bits off your iPod and ship them directly to the amplifier without converting the music to analog form. The bad news is docking station can’t be sold in the US. I was able to find a mail order house in Japan that could sell me my illicit docking station. The AI-501DA amplifier connects directly to the PC via USB cable. In my past life I was one of the authors of the USB audio specification and was instrumental in supporting USB audio at Microsoft. The AI-501DA can source input from the PC via USB or the docking station via optical or RCA S/PDIF connection. In both modes there are no unnecessary digital to analog conversions. The Teac AI-501DA is one of the few amplifiers that is designed to take digital input. As a class D amplifier it uses MOSFETs. These are transistors that were designed for power supplies and power converters. Conventional analog amplifiers (both tube and transistor) have a low power analog input that controls a higher power output. It is an ideal goal that the output is linear in respect to the input. Not all amplifiers are linear, but this is not necessarily considered to be a bad thing. In a class D amplifier, the MOSFET switches on and off hundreds of thousands or millions of times a second and approximates the digital input signal. There are many people who like tube amplifiers and their non-linearity. Class D amplifiers either work or don’t work and are linear. Analog amplifiers have a linear range, but when driven hard, they can distort. Class D amplifiers are always linear. If they are shorted out, they just turn off. Since all of my recorded music is in digital form, I prefer the Class D amplifiers. People regularly tell me how soulless I am particularly after drinking my single malt. I enjoy tube amplifiers with vinyl records. My friends who introduced me to great recorded music are all dead. I hope some people on this list may have inherited their Thorens turntables and Macintosh amplifiers. While I have great memories of days gone past, I don’t own any analog recordings. One reviewer suggested the AI-501DA was an overpriced, but fine amplifier that would appeal to a limited set of fanatics. Since I spent several years of my life making USB audio work on Microsoft operating systems, I qualify as a certified fanatic. With that as a caveat, the speakers sound much better after I replaced the Denon with the AI-501DA directly connected to my PC via USB cables. To answer my original question, the amplifier has plenty of power. The RF-7s are very efficient, and I can turn them loud enough to make it painful to be in the room. I can’t use the subwoofers. Later Klipsch subwoofers support high level inputs as well as a low level LFE input. I now have a 150lb subwoofer sitting by my system. The Teac has no LFE output. I don’t really miss the subwoofer, but I’d like to hear it with the new system to make a decision. It seems a shame to let that much hardware sit idle. The AI-501DA supports 24-bit audio at 196K samples per second. Microsoft only supports 16-bit 48K samples per second audio over USB. Teac has their own USB audio drivers. As former Microsoft program manager for USB audio, this galls me. I was hoping I could hear some difference between HD audio and ‘mere CD’ quality, but I have downloaded some HD audio and played it through this system, but these 66 year old ears can’t tell the difference between HD audio and my CDs that have been ripped into highest quality Windows Media Audio format. The AI-501DA is overpriced at $800 and some change, but it sounds a lot better than the Denon which was connected via an analog cable to whatever audio chip is in my Dell. It is tiny; less than a quarter size of the Denon and very good looking. I love the Vu meters. The volume control and power switch have a great feel to them. If you use the remote control to change the volume, the knob turns. This sort of stuff isn’t supposed to be important, but it is fun. Thanks to all of you who encouraged me in this foolishness. If anybody has ideas as to how to use my subwoofer, I am open to suggestions.

It is not a large room, and has hardwood floors with throw rugs. I am sitting about 8 to 10 feet. I am convinced that the amp will work with these speakers, but a friend has some 10 year old Klipsch in a garage with an amplifier. I will everybody know what they are when I get over there in two weeks.

BillyBob: Thanks for responding particularly for a newbie. I am still researching the system I will be putting together. I was incorrect that the AI-501 DA puts out 90 watts. That was the figure for 4 ohms. The real figure is more like 30 watts continuous and 45 watts max at 8 ohms. As the RF-7 II has 8 ohms input, I must use this lower figure as to how much power I have available. The good news is the RF-7 II is a very efficient speaker at a sensitivity of 101dB. According to the chart on the general-faq page on this website, I should be able to generate around 114 dB of sound pressure with the wattage I have available with my amplifier. This is more than I need to bring to Nora Jones and her piano into my living room. I understand that the RF-7 II is capable of putting out a lot more sound volume, but I think of the “Ode to Joy” chorus is about as loud as I want in my living room. If I open a disco nightclub, I will buy a new amplifier. I don’t own a turntable nor any vinyl records. My music will come from a PC via a USB connection. I am also planning on getting a Teac DS-H01 docking station for IPod and IPhone as my guests like to bring their own music. This docking station provides a direct digital connection to the AI-501 DA amplifier via Tascam or SPDIF RCA jack connection. This configuration should give me ample opportunities to experiment with multiple formats for audio as the amplifier supports 24-bit audio at 192 KHz. I don’t know if more is better in this case, but it will be fun to experiment with different formats and compression techniques.

This amplifier is rated at 90 Watts per channel, but it is type D amplifier. It allows a computer to play 24 bit audio at high bit rates over a USB connection.