Valleyman -
Some real good points and tips as well.
Regards 'test' speakers. I have more drivers in this house than you can count. Am I correct to assume a tweeter is worthless for this purpose ? Reason I ask is I'd rather blow up my cheapest stuff 1st and I bought a boatload of Onkyo buyout tweets from P.E. just because they were 20 cents. I also own a bunch of little FR's that were given to me that would be 2nd. on my list. Next would be my NSB's but I like them things .
Thats funny isn't it? Deciding which of your collection you want to blow up 1st?
Might as well get extra chips right off the bat. Can anybody give me an idea what Digi Key is charging for shipping these here in the States?
Bluto
Some real good points and tips as well.
Regards 'test' speakers. I have more drivers in this house than you can count. Am I correct to assume a tweeter is worthless for this purpose ? Reason I ask is I'd rather blow up my cheapest stuff 1st and I bought a boatload of Onkyo buyout tweets from P.E. just because they were 20 cents. I also own a bunch of little FR's that were given to me that would be 2nd. on my list. Next would be my NSB's but I like them things .
Thats funny isn't it? Deciding which of your collection you want to blow up 1st?
Might as well get extra chips right off the bat. Can anybody give me an idea what Digi Key is charging for shipping these here in the States?
Bluto
Yes, I'd encourage a beginner to start with a kit, or a diy on vero, or even a pre-built.
Pre-built? Is that okay? Yes. Just trust me when I say that the "hard part" is actually putting the amplifier into the enclosure, connecting up the pot, speaker terminals, rca jacks, heatsink, power cord, and optional source selector.
When choosing a kit, its pretty obvious that Audiosector is a good choice. Peter, the owner, has posted much helpful information at this thread.
If I have gathered the specific information correctly, the LM3875TF Audiosector kit's approved configuration for AC coupled (use any source) is:
source. . .potentiometer. . . 4.7uF (he said Blackgate N 50v). . . 15k input impedance resistor (instead of 22k).
I like his "stereo" layout quite well. Its extremely durable, quite elegant, and, like a magic genie, the engineer appears whenever you need help--just rub the side of the amplifier, or, actually, post a question at this forum.
I'm providing another option for if you're short on cash or just want to make your own on phenolic board. The design is complete and is just awaiting proofing. There's not any deliberation or agonizing on design. Its already done.
Pre-built? Is that okay? Yes. Just trust me when I say that the "hard part" is actually putting the amplifier into the enclosure, connecting up the pot, speaker terminals, rca jacks, heatsink, power cord, and optional source selector.
When choosing a kit, its pretty obvious that Audiosector is a good choice. Peter, the owner, has posted much helpful information at this thread.
If I have gathered the specific information correctly, the LM3875TF Audiosector kit's approved configuration for AC coupled (use any source) is:
source. . .potentiometer. . . 4.7uF (he said Blackgate N 50v). . . 15k input impedance resistor (instead of 22k).
I like his "stereo" layout quite well. Its extremely durable, quite elegant, and, like a magic genie, the engineer appears whenever you need help--just rub the side of the amplifier, or, actually, post a question at this forum.
I'm providing another option for if you're short on cash or just want to make your own on phenolic board. The design is complete and is just awaiting proofing. There's not any deliberation or agonizing on design. Its already done.
Bluto said:
Sound cards and other trouble sources:
The majority of PC sound cards, notably quite a few that claim high end, do contain the very cheapest op amp chips.
Also
The majority use a digital gain control volume system, whereby the ouput gets lesser quality as the gain goes up. Now, that's not bad news for relaxing listening, but jamming out could be met with defeat.
However, it should go fine on the updated circuit that I posted, with gain 35, a groundlift resistor, a dc blocker cap, and a cap compensator resistor. Success with modern use is exactly what the design is for. Its 2008 now and CD availability has been falling for some time, so we might as well have a 2008 amplifier design with success on a variety of source devices.
I can't do anything about codec (software) gain; but you can. Discontinue use of Windows Media player in favor of something with the ReplayGain feature. Foobar2000 is scott free and has that feature for all music files. Coolplayer does it manually, with a control, but it can't play wma. Also, check out converting to .WAV (cd) with good quality software on its slowest setting (High Quality), which isn't the default option. Convert to .WAV before making audio CDs (good backups in case of a computer crash). See other discussions about hifi codecs. After all, its your music, and you may as well hear it.
Next topic:
Surround sound, software enhancement, software equalizations, and EAX, CMSS, hall effects, etc. . . the whole gang shreds up and disposes of the natural ambients that are individualized per each individual recording, and then this bit of tomfoolery goes on to replace the natural ambients with a fake. The technology has a great use, but home playback isn't it. In the home, the presentation of every recording coming from the same site, can cause listening fatigue (due to the fakery of one boring "location" all the time).
The natural on-site recorded ambients are part of your music purchase, so please don't waste it.
See this discussion on non-fake surround sound. http://www.linkwitzlab.com/surround_system.htm
It works with a standard stereo hifi running the main two channels, while the surround effects are substituting for room reflections without shredding up the details. This approach, as I understand it, is "replacing your room without replacing parts of your music" or so it seems.
An option to this computerized mess is a hifi USB DAC, which is an adaptor that circumvents the junk on the sound card.
You'll still need good playback software, though. This dandy little device contains a preamplifier, which, hopefully, allows enough headroom so that your "CD era" audio equipment can do a good job on internet music purchases.
Bluto said:
Although the new design is so simple that it should work for quite the variety of applications, I'm waiting on more thorough testing.
My reservation (and additional testing) comes from the polite "non comment" of post #131, where Peter liked the 15k input impedance, but made no comment on other resistor settings.
The possible meanings are:
1). Didn't like the design
2). Doesn't go with the Audiosector kit
3). Would do something differently
4). Wasn't as interesting as the 15k deal
Possibilities 2 and 4 are a sure thing, leaving no information whatsoever about possibilities 1 and 3.
Last time, it was #3, so more "exploration" and testing is indicated.
In the mean time, it would be great to figure out how to get the chipamps into the amplifier enclosure as easily as possible.
Enclosure:
I've just got 3 things here on the enclosure.
1. It would be nice if hot air went up. So, its good to provide a means for air to enter underneath the heatsink. Its good for hot air to exit the top (or top of the back panel) of the enclosure.
Air in, air out. Otherwise hot air doesn't go up.
2. The heatsink represents an opportunity to, A) ground it (chassis neutral), and then B) use it for a sheild. While I've never personally had any trouble with an EI core (square) transformer, the established means to be absolutely sure, is to face the "fin side" of the heatsink "towards" the transformer. Sheilds up, captain!
3. The front and rear panel should probably be thin enough so that your potentiometer dial, power switch, rca jacks, ect. . . can mount to it.
Any other enclosure ideas?
I've just got 3 things here on the enclosure.
1. It would be nice if hot air went up. So, its good to provide a means for air to enter underneath the heatsink. Its good for hot air to exit the top (or top of the back panel) of the enclosure.
Air in, air out. Otherwise hot air doesn't go up.
2. The heatsink represents an opportunity to, A) ground it (chassis neutral), and then B) use it for a sheild. While I've never personally had any trouble with an EI core (square) transformer, the established means to be absolutely sure, is to face the "fin side" of the heatsink "towards" the transformer. Sheilds up, captain!
3. The front and rear panel should probably be thin enough so that your potentiometer dial, power switch, rca jacks, ect. . . can mount to it.
Any other enclosure ideas?
Greg Erskine said:
The Squeezebox is a networking tool, able to transfer data intact; however, its inbuilt sound fares no better, no worse than the common "sound card upgrade" products. An exception is that the Squeezebox has a digital output port where you can plug in a real HiFi DAC to bypass the retail-grade sound mess inside the Squeezebox.
So, for wired/wireless networking of audio with Squeezbox, its:
Computer
Network
Squeezebox
HiFi DAC
Preamplifier*
Amplifier
Speakers
*The preamplifier may not be necessary if the HiFi DAC has sufficient gain when at 2/3rds or lower output.
danielwritesbac said:
Although the new design is so simple that it should work for quite the variety of applications, I'm waiting on more thorough testing.
My reservation (and additional testing) comes from the polite "non comment" of post #131, where Peter liked the 15k input impedance, but made no comment on other resistor settings.
The possible meanings are:
1). Didn't like the design
2). Doesn't go with the Audiosector kit
3). Would do something differently
4). Wasn't as interesting as the 15k deal
Possibilities 2 and 4 are a sure thing, leaving no information whatsoever about possibilities 1 and 3.
Last time, it was #3, so more "exploration" and testing is indicated.
In the mean time, it would be great to figure out how to get the chipamps into the amplifier enclosure as easily as possible.
He simply doesn't like to complicate things, if something works fine for years, why changing it?
Peter Daniel said:He simply doesn't like to complicate things, if something works fine for years, why change it?
Thanks man! I understand.
My only answer to that question is that I would like for the design to outlive CD technology. Of course there are more elegant options than the simple passive buffer that I presented; however, it was requested.
I'd rather. . .
It would be great if Audiosector had a cool little preamp kit for use with chipamp projects, in that would make the whole "preamp thing" to be ever so much easier, because of the durable and elegant nature of your kits. Maybe even a preamp kit with onboard USB DAC (both analog and USB inputs)?
I would like to see the "active" powered options presented. So, if you'd like to advertise them, please do, because it would be highly useful for beginners to know how to get their music purchases into their amplifiers as nicely as possible.
Dan, a buffer is there to match impedances between source (output) and amplifier (input). For that reason, it cannot be "passive" (unless you use a transformer)!
A good example of what you ask for will entail the use of SMD (surface mount) components rendering it unsuitable for beginners. If somebody has been able to complete a chip amp, they should be more than capable of building either a simple buffer or pre amp. Like the chip amp, there are comparatively few components involved, and they can easily be constructed on strip-board.
Dan - have you heard of re-inventing the wheel?
Your assessment of the Squeezebox system is quite correct. In my experience, whether you need that extra gain in a pre-amp is also down to the efficiency of the speakers involved. But even if there is enough gain, you may need a buffer for the purposes of impedance matching.
But I can't help feel this thread is now a long way on (off?) from gychang's original question.
What a Thread !!
This thing is somethin else.
You can't go away for more than a few hours (I just did) or you miss plenty.
Andrew T - Regards your post # 175 . My confusion is now eliminated, I hadn't looked far enough to find the connection, nor had others who saw things the same way. See posts #2 and posts #14. For anyone who has read posts #3 - #13 as well I think the die was cast.
Nuuk - Regards your posts # 174 and #176. Both of these make me wish you had been involved earlier than you were. Excellent points again. The SMD was part of what had troubled Gychang from the onset.
Bluto
This thing is somethin else.
You can't go away for more than a few hours (I just did) or you miss plenty.
Andrew T - Regards your post # 175 . My confusion is now eliminated, I hadn't looked far enough to find the connection, nor had others who saw things the same way. See posts #2 and posts #14. For anyone who has read posts #3 - #13 as well I think the die was cast.
Nuuk - Regards your posts # 174 and #176. Both of these make me wish you had been involved earlier than you were. Excellent points again. The SMD was part of what had troubled Gychang from the onset.
Bluto
Nuuk said:Dan, a buffer is there to match impedances between source (output) and amplifier (input). For that reason, it cannot be "passive" (unless you use a transformer)!
. . .
Dan - have you heard of re-inventing the wheel?
. . .
But I can't help feel this thread is now a long way on (off?) from gychang's original question.
The impedance change is the input filter cap, with the assumption that the cap is the source--a PA alternative. Its no secret that I'd have rather used a preamp. That wasn't wanted. Okay. I'm aware that the term "passive buffer" implies that its a cheat. That's exactly right. Hey, its about 8 cents, very simple, and it has been working well so far. This is, by request, a "no preamp" project.
However, I would like to see some non-confounding preamp options presented. And, where are they?
Gychang's original question? Oh, I'm working on that one. Its going quite well. Waiting on post office.
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