[MakeLV] Stereo components

Fri Nov 16 12:49:19 CST 2012

Those are 8 ohm speakers. What I had in my old stereo was Infinity
Reference 6x9's that could run at 100 watt RMS per channel. The speakers
you mentioned will not work without messing with a crossover network. While
doable, not very robust for a work environment.

-Will C

On Fri, Nov 16, 2012 at 1:42 PM, William Weik <wweik at lutron.com> wrote:

> I have multiples of these available to donate if you would like some, I
> know its not really what your asking for but its an option.****
>
> the woofer is capable of going down to around 60hz which is pretty
> impressive for its size.****
>
> ** **
>
> http://www.parts-express.com/pe/showdetl.cfm?partnumber=270-175****
>
>
> http://www.madisoundspeakerstore.com/approx-5-fullrange/aurasound-ns525-255-8a-5.25-paper-cone-8-ohm/
> ****
>
> ** **
>
> -Will W****
>
> ** **
>
> *From:* Makelehighvalley [mailto:
> makelehighvalley-bounces at makelehighvalley.com] *On Behalf Of *Will
> *Sent:* Friday, November 16, 2012 1:20 PM
>
> *To:* Build things for fun!
> *Subject:* Re: [MakeLV] Stereo components****
>
> ** **
>
> Good news! With the help from Jordan (a new comer to the space who shows
> up on open hack nights) we have a working stereo! It's on what will become
> the microcontroller work bench. At this time the amp is not mounted so
> please do no move the stereo system in a computer case if it can be avoided.
> ****
>
> ** **
>
> With that said, some proper speakers are desired at the space. Some 6x9's
> would be perfect (that can run at 75watt RMS at 4 ohms or 150watt RMS at 2
> ohms). I'm looking at some speakers and I will have to build new boxes. If
> anyone has some speakers lying around right now and would like to donate
> them temporarily please do so. What we have sounds ok but we are lacking
> base (yes.... there is a sub woofer design that can be done at a later
> time).
>
> If anyone would like to use the stereo, please speak to me prior because
> there is a 90% chance of failure for people to be unable to turn the system
> on if they aren't given a brief introduction. Afterwards, there will be the
> ability to connect any device via RCA connections or play CD's (regular
> CD's and MP3 CD's). ****
>
> ** **
>
> -Will C****
>
> On Wed, Nov 14, 2012 at 12:04 AM, Will <staticphantom at gmail.com> wrote:***
> *
>
> When it comes to tube amps, the only real application of them are when you
> want distortion. I will admit that they tend to have some fun and
> interesting distortion characteristics that are good for radio, but mostly
> are amazing for guitar amps (if you listen to ZZ top and love the sounds,
> you love tube guitar amps). Tube amps are great project that can be scaled
> down in cost with headphone amplifiers which is another reason to go to the
> Cmoy (it's the gateway audio amp drug/project). ****
>
> ** **
>
> As for a comment stated earlier... you actually do need a pre-amp for a
> home stereo. The high end receivers provide the low noise amplification and
> used to help with proper impedance matching for amplifiers (which are often
> rack mounted). Granted for those system, when people get that serious the
> speaker wire for the front two channels may cost in excess of $600. Now I
> will warn everyone at the space, I don't care how much an audiophile you
> are but if anyone spends over $200 for less than 24ft of wire I will slap
> them. In addition, I don't want anyone at the space claiming the need for
> cryogenically treated wire.****
>
> ** **
>
> Anyway... back to the subject at hand. I will be at the space tomorrow and
> I look forward to working on my stereo. I will say I need to build new
> speakers so if anyone has 2 ohm or 4 ohm speakers they would like to make
> temporarily available I would be most appreciative. ****
>
> ** **
>
> -Will C.****
>
> ** **
>
> On Tue, Nov 13, 2012 at 11:49 PM, <rsjames at ix.netcom.com> wrote:****
>
> ** **
>
> Ah,now I understand better.  You don't need the pre-amp to feed into a
> "home" stereo amp, you need it to feed into a car amp.  Since car amps are
> designed to be driven from the output of  a car stereo, they need a lot
> more juice than your typical microphone pre-amp will drive.  Using the Cmoy
> makes a lot more sense to me now. ****
>
>  ****
>
> Putting the volume control pot in place of the "Rg" in the non-inverting
> circuit is a good way to do it.  If you replace both "Rg" and "Rf" with the
> pot (connecting the wiper to the non-inverting input), you get much greater
> amplification range.  Of course, for this circuit you don't need or want
> that.  The other way to do it is to just hang the pot right off the
> output.  This works great if the impedance of what you are driving is
> substantially higher than the pot value.  That would be the case for a line
> input on a home stereo, but I'd bet that the input impedance of the car amp
> is pretty low, so probably not a good way to do it.  Another point, for
> people who aren't all that familiar with electronics, is that when you turn
> a pot all the way to one end, it has a resistance of zero - a dead short.
> Depending on the circuit, this may cause damage.  The typical solution is
> putting a resistor in series with the pot.  It is not uncommon to see pots
> with series resistors on both sides, particularly in feedback
> loops.         ****
>
>  ****
>
> I consider the skillful use of ferrites to be one of the Black Arts.
> Another trick with computer supplies is to use them to feed a linear supply
> circuit.  A couple of big ol' caps help to tame the high frequency
> garbage.  Add an adjustable regulator on a heat sink, and you have a handy
> variable supply.  But you will still probably need ferrites!****
>
>  ****
>
> My comments about the resistors was more in response to the writeup on the
> Cmoy.  There are a lot of things about that circuit that have a greater
> effect on the output than the resistor tolerences.  You are right on about
> only needing to be close and inexpensive.  I remember the days of carbon
> resistors.  A high quality circuit would use 10 percenters, maybe even a
> few 5 percenters for critical signals.  Everything else was 20
> percenters.  1% resistors were usually wire wound, and very expensive
> (compared to other resistors).  The manufacturers would make the carbon
> resistors, and then measure them to determine the tolerance.  That meant if
> you had a 10% resistor, it was off by more than 5%, otherwise it would have
> been sold a a 5% resistor.           ****
>
>  ****
>
> With respect to tube amps, I happen to like tube circuits.  They glow!
> Also, they keep you warm on cold days.  I can't think of any other real
> advantages.  ****
>
>  ****
>
> RSJ                      ****
>
> -----Original Message-----
> From: Will
> Sent: Nov 13, 2012 4:41 PM
> To: Build things for fun! ****
>
> Subject: Re: [MakeLV] Stereo components
>
> First of all, your response are all great points worth mentioning. What
> bringing up includes the following.  ****
>
> ** **
>
> 1) Need, the goal is to use some amplifiers that are cheap and easily
> attained. In this case, car audio amplifiers. They are robust and make for
> great shop systems. The problem with these amplifiers is that a computer or
> CD player just doesn't have enough power to properly drive the amps to
> acceptable levels. ****
>
> ** **
>
> 2) I like the Cmoy because it is basic and people can get hands on
> some fundamental electronics. I'm all for a wall wart... however seeing how
> the basic design for using car audio uses computer power supplies (of
> which... we have quite a few at the space). Computer power supplies are
> also fun because they can bring a whole host of problems to audio. Much of
> the problems provide a fun learning experience that includes ferrite beads!
>
> I do like the fact that volume controls are separate because it allows for
> a space to be equalized a little better in if working with a mono signal
> (it might work as basic PA system but I won't know until we try). I agree
> with the comment about screwing up input impedance's with putting a pot in
> the input. Ideally I would recommend putting a POT where Rg is in the
> inverting configuration described here
> http://en.wikipedia.org/wiki/Operational_amplifier. That is the best way
> to adjust gain on an amplifier however it will cause distortions.  ****
>
> ** **
>
> 3) I could give a crap about resistors. If people want to sit down and
> change the resistance with a file to get perfection then have at it. I'm
> fine as long as the tolerances are close (which are still inexpensive). #1
> rule about audio, don't fall down the rat hole of audiophiles that point at
> everything that isn't perfect to justify dumping money. (See tube
> amp enthusiasts).****
>
> ** **
>
> 4) Power supplies... however for 9 volts I think we may have a problem and
> would need either a 12 volt power supply line from a power supply or use a
> regulator to drop down the voltage (we might be able to do something with a
> resistor network pending some measurements). I know the 741's could take
> those supply lines but the ones for the Cmoy, no clue and I will have to
> look at the data sheet. ****
>
> ** **
>
> 5) As much as cheaper alternatives are there, the nice part about the Cmoy
> is that the design can be easily taught and constructed. In the end, it's
> something to be proud of in terms of quality which I think is perfect for
> the space. ****
>
> ** **
>
> As far as end purpose, Jonas will need to comment because I was speaking
> in terms of something for the class room. I don't know what Jonas wants
> exactly, he will have to let us know. ****
>
> ** **
>
> -Will C. ****
>
> ** **
>
> ** **
>
> ** **
>
> On Tue, Nov 13, 2012 at 9:37 AM, <rsjames at ix.netcom.com> wrote:****
>
> Looks like your basic generic inverting op-amp circuit, run off
> of batteries.  Not sure why you say we need a pre-amp.  What signals are we
> amplifying?  Do you want microphone inputs to the amp, or are you playing
> music?
> I have a few thoughts about the circuit:****
>
> 1. If you are using it as a pre-amp, you shouldn't need two batteries for
> the supply.  The output doesn't need to swing that far.  If it doesn't need
> to be portable, use a plug in supply.  (Use a wall wart with some extra
> filtering caps.  You could even throw in a voltage regulator, but probably
> not needed.)****
>
> 2. There are separate volume controls for each channel, but no common
> control.  Okay if not using it for stereo.  Otherwise you have to adjust
> two controls every time you change the volume.****
>
>   2A. Putting the volume control on the input is wrong for a pre-amp.  It
> really messes with the input impedance.     ****
>
> 3. In the parts discussion, he talks about using precision resistors.  If
> you want, you can use precision resistors, build the circuit, connect a
> high quality signal generator to the input, put the correct load on the
> output, and connect a dual trace oscilloscope on both the output and the
> input.  You can then adjust the volume control pot to get exactly the level
> you want at the output for a given input.  Or, you can just use cheap
> resistors, and adjust the volume to the level you like.  Your money.  ****
>
> 4. He also talks about using better resistors to avoid problems with the
> resistance changing due to temperature.  The alternative would be to not
> build the circuit in a metal box!  Also, the output of the 9 volt batteries
> change with both temperature and age.  The power is unregulated, so this
> will have more of an effect than the resistor tolerances.****
>
> 5. The recommended op-am is a very nice, rather expensive part.  If you
> are building a true audiophile quality circuit, it would be a good choice.
> If you are looking for a low cost solution, there are many better
> choices.  Heck, you could even use an audio amp IC, or is that too obvious?
> ****
>
>  ****
>
> A few other thoughts:****
>
> There are pre-amp kits out there that would probably be cheaper.  Most of
> the cost of a low cost audio circuit is in the connectors!****
>
>  ****
>
> If you really want to do this cheaply, hit up thrift stores and yard sales
> (Goodwill, Salvation Army Thrift Shop, etc.).  I was at a yard sale this
> past weekend, and there was a microphone preamp.  It was an a 4 or 8
> channel rack mount unit, and I think the guy wanted $25 bucks.  I though it
> was kind of high.  You can easily get all sorts of receivers and tape
> players for cheap.  They practically give away VHS and CD players, both of
> which have usable circuitry.****
>
>  ****
>
> R. S. James****
>
>  ****
>
> ** **
>
> -----Original Message-----
> From: Will
> Sent: Nov 13, 2012 2:01 AM
> To: Build things for fun!
> Subject: [MakeLV] Stereo components
>
> Hey all,  ****
>
> ** **
>
> Good news! The replacement amplifier has arrived for the space. In the
> excitement of taking a look at the new amplifier.... I found a small 150
> watt Rockford Fosgate stereo amp in the basement. I know Jonas was
> mentioning need for another speaker system for the class room section. To
> that.... I have an answer that requires another hack that has been done
> multiple times (and could use a custom PCB). ****
>
> ** **
>
> To use any amplifier a pre-amplier is needed in a similar configuration to
> my sound system. In high end sound systems a receiver usually performs this
> function (lower end audio on home stereos have the amplifier and receiver
> in a single unit) then sends a low noise signal to the amplifiers. To
> perform the function on of a head unit on my stereo as a receiver  a
> headphone amplifier can be built to act as a receiver.  The best headphone
> amplifier out on the market that audiophiles rave about is the CMOY (
> http://tangentsoft.net/audio/cmoy-tutorial/) can be produced for around
> $20. ****
>
> ** **
>
> I am willing to build a new stereo system when I can, however if someone
> like to expedite the project by taking ownership feel free to contact me.
> ****
>
> ** **
>
> -Will C. ****
>
>
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>
> ** **
>
>
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>
> ** **
>
> ** **
>
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