"Bob-Stanton" wrote in message
om
"Arny Krueger" wrote in message
As if high price makes an amplifier necessarily more distortion
free, or low price means it has to have audible distortion. Just
isn't true!
Which of the low priced amplifiers is totally transparent?
A couple of points.
(1) I didn't say totally transparent, I said "more distortion" and "more
distortion free".
(2) At this point there is no formal definition of "low-priced"
Do you have this information on your website?
For example, the near-universal choice to use electronic crossovers
with subwoofers has a lot to do with the costs and inconveniences
related to making a passive crossover at say 50 Hz for a 8 ohm
speaker that is designed to work with a low source impedance.
That's right. For a *very* low frequency crossover (60 Hz), the
component cost is high. However, the cost of components, for a 2kHz
crossover, is low.
Right and at that crossover point, electronic crossovers don't generally
make much sense, except for systems with more dynamic range than a typical
home system.
Potentially problematical given that so many power amps have input
impedances of less than 50 K.
One should check for conventional input impedance (50k to 100K) before
buying.
One then finds a lot of power amps with input impedances in the 5-20K range.
Since the crossover has only four components, (two capacitors, one
resistor, and one pot) it is easy to build. You can build it on a
Radio Shack eight phono jack board. Part# 274-370, (cost $2.19).
IMO if you are going to do something, do it *right*.
What is wrong with building a crossover on a Radio Shack phono-jack
board?
Most the limitations forced on it because its passive.
This crossover has the advantage over active crossovers, in that it
has less distortion.
It has less noise, too but in fact noise and distortion from
reasonably good, modern electronic crossovers just isn't a problem.
Yes, active electronic crossovers have very very low distortion. All I
said was, passive electronic crossovers have lower distortion. OK, it
doesn't matter, but they do have lower noise and distortion.
The we agree.
Here's an example of a good, modern, relatively inexpensive but
comprehensive electronic crossover of the digital persuasion:
*Very nice*, but not for an $800 budget.
Buying twice or three times as many power amps pretty well creams a $800
system budget. Interestingly enough, a $800 system based on better quality
parts from the PC monitor or One Box Home Theater market segment would
probably end up with an active crossover.
Please see my 7/16 post about subwoofers.
Again price really doesn't have that gosh awfully much to do with
it. Once you get past the crappy drivers (which sell for a wide
range of prices ranging from low to high) you can find a lot of
reasonably-priced drivers with good performance including ability to
work with low-slope crossovers.
Again, price doesn't matter if you *know* which cheap drivers are the
good ones. Do you have this information on your website?
Nope, because my knowledge of the area is not up to the standards for my
websites. But I've experimented and looked around enough to have an idea
about what can be done.
Rolling your own loudspeakers and getting good results is far from
simple unless you stick to subwoofers. Doing a two-way
woofer/tweeter speaker system *right* is actually one of the tougher
technical chores around.
Going to an electronic crossover *greatly simplifies* the design
problem.
Well, at the cost of the extra amplifiers, which in a $800 total system cost
for a system assembled by a consumer, makes things pretty tough.
Here is how to design a speaker system using an electronic crossover:
1) Stick to a two-way system. (If you want three-way system, buy a
subwoofer with an integrated amplifier, and make your satellite
speakers two-way.)
Right, and at $800 system cost, it is probably best to stick with passive
2-way speakers.
2) Buy a woofer that is of good quality from Vifa, or Audax or
Scan-Speak. Pick drivers that don't require a compensating network to
be flat.
Again, Rolling your own loudspeakers and getting good results is far from
simple unless you stick to subwoofers. Doing a two-way woofer/tweeter
speaker system *right* is actually one of the tougher technical chores
around.
Most experiences speaker builders agree with this. I admit that I'm working
on a high-performance 2-way design, but it exceeds most
commercially-available 2-ways a number of ways, mostly relating to frequency
response extension and dynamic range. Also, the total system price that goes
with it will be far in excess of $800. I
3) Pick a woofer that is designed to work into a closed box. (Avoid
buying woofers that need to work into ported enclosures.)
????
4) Note what volume enclosure the manufacture recommends, and buy or
build, a *sturdy* enclosure of *that* volume. Fill it lightly with
(acoustic) fiberglass.
Most manufacturers of quality woofers provide T/S parameters and leave the
design up to the purchaser.
5) If the tweeter isn't sealed on the back, mount it in a seporate
enclosure.
Nope, just don't buy it.
6) Solder a series resistor-capacitor across the driver terminals.
------------------------------
| |
R = 8 Ohms |
| 8 Ohms driver. (Woofer or Tweeter)
C |
| |
------------------------------
The value for C depends on the inductance of the driver.
For the typical (8 Ohm) woofer, the value of C = 15 uF.
For the typical (8 Ohm) tweeter, the value of C = 1 uF
Zoebels are for people who don't get it.
Here's your chance to invest in measurement and analytical tools!
The good news is that they are far less costly today than they were
years ago.
I agree. Cooledit for $69 has an excellent little spectrum analyzer.
Been there done that and I wouldn't recommend it to even someone I don't
like. If you want a superior tool for lots less money, check out
http://audio.rightmark.org/ Scroll down the download page to Rightmark AE.
Its better than CEP for the purpose, but I could write quite a bit about its
strengths and weaknesses.
If you want two good small two-way speakers, you will probably save
money (not to mention time!) in the end by looking at speakers from
manufacturers like Paradigm, NHT, PSB. Boston Acoustics, etc.
Are prebuilt speaker system as low cost as similar ones you build
yourself? I doubt it.
The price/performance and time investment is hard to beat.
Again, Rolling your own loudspeakers and getting good results is far from
simple unless you stick to subwoofers. Doing a two-way woofer/tweeter
speaker system *right* is actually one of the tougher technical chores
around.