Turning on light switches, or my house AC turning on, generates a popping sound in my speakers. Is this due to a ground loop, the electronics not being in an enclosed case, or due to signal wire being just twisted (i.e. not shielded).
Btw, what is the best shielded wire to buy for wiring signal internally?
Btw, what is the best shielded wire to buy for wiring signal internally?
hard to say exactly, as it could be one or more possibilities, as mentioned, so the idea is to use method of elimination,
test with the input signal grounded first, to determine if it is generated externally and coupled through the input signal. Could try grounding at your input connector and then ground right at the amp input on the pcb.
try to power from another a/c receptacle, to see if it is conducted.
Figure out source first then we can try to make a fix.
If you have a scope, monitor the supplies, signals looking for the noise spikes.
For shielded wire, foil plus copper braid works okay. keep lengths to a minimum and keep away from strong radiators like the a/c line.
test with the input signal grounded first, to determine if it is generated externally and coupled through the input signal. Could try grounding at your input connector and then ground right at the amp input on the pcb.
try to power from another a/c receptacle, to see if it is conducted.
Figure out source first then we can try to make a fix.
If you have a scope, monitor the supplies, signals looking for the noise spikes.
For shielded wire, foil plus copper braid works okay. keep lengths to a minimum and keep away from strong radiators like the a/c line.
At one point I had no hum nor noise from switches (or the nearby paper shredder).
I was using a 100k alps pot I bought from chipamp.com with the PCB.
Using a 10k alps pot now with DIY pcb from perf board.
One difference between the pcb's is that the one from chipamp.com has the left and right in/out grounds all tied together as one ground. On mine I isolated the grounds. I just tied in/out together but kept the grounds for each channel separate.. is this my problem?
I was using a 100k alps pot I bought from chipamp.com with the PCB.
Using a 10k alps pot now with DIY pcb from perf board.
One difference between the pcb's is that the one from chipamp.com has the left and right in/out grounds all tied together as one ground. On mine I isolated the grounds. I just tied in/out together but kept the grounds for each channel separate.. is this my problem?
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It is a bit of trial and error.
I'd say isolate the ground at the rca i/p from the chassis. Carry the ground, (in a shielded wire along with the signal), from the rca i/p jack, through to the pot ground and then terminate the ground at the power amp input ground. Then at that point, run your ground wire to the common point ground, where the trans center tap meets the big ecap grounds.
Also get yourself a metal enclosure, asap, a cardboard box is not a safe way to prototype live circuits. With a metal box you have the option of using chassis ground for your a/c earth ground.
I'd say isolate the ground at the rca i/p from the chassis. Carry the ground, (in a shielded wire along with the signal), from the rca i/p jack, through to the pot ground and then terminate the ground at the power amp input ground. Then at that point, run your ground wire to the common point ground, where the trans center tap meets the big ecap grounds.
Also get yourself a metal enclosure, asap, a cardboard box is not a safe way to prototype live circuits. With a metal box you have the option of using chassis ground for your a/c earth ground.
I can't remember your schematic.
Did you have RF attenuation filter at the input?
I run most of my gear as uncased temporary lash ups and I don't get any symptoms of interference either radiated through the air, eg mobile phone, or wirelesss landline, nor through the cables from unattenuated or badly attenuated switching of motors etc, eg washing machine, or fridge/freezer.
Did you have RF attenuation filter at the input?
I run most of my gear as uncased temporary lash ups and I don't get any symptoms of interference either radiated through the air, eg mobile phone, or wirelesss landline, nor through the cables from unattenuated or badly attenuated switching of motors etc, eg washing machine, or fridge/freezer.
Andrew, I don't have any filters. I just run the dac rca's to diy passive 10k preamp in cardboard box. I split from there to the lm3886 and to the powered sub. Then I run into rca's that are isolated from the chassis until it gets to the amp pcb which join together all input and output grounds along with the neg and pos grounds from the power supply.. under the pad CHG... which runs from there to chassis ground.
6 ohm is perfect from POV the LM3668 data sheet (makes sense right)
8 ohm would be ideal for a full ranger 1) you don't need or cant use the full power and 2) IMD will be better.
4 ohm would be reaching for max power, but your V rails means current or some other SPIKE protection could kick in 1st.
full ranger a FF85xx would be something I would like to hear, but Im afraid couldn't live on it, all by itself cept maybe some simple tunes. I reckon your music to be the final judge on that.
8 ohm would be ideal for a full ranger 1) you don't need or cant use the full power and 2) IMD will be better.
4 ohm would be reaching for max power, but your V rails means current or some other SPIKE protection could kick in 1st.
full ranger a FF85xx would be something I would like to hear, but Im afraid couldn't live on it, all by itself cept maybe some simple tunes. I reckon your music to be the final judge on that.
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I guess I meant a 3-way not a full range. When I said "full range" I meant I wanted a speaker that could handle the bass beyond what my 6 inch bookshelf speakers are putting out. Like a 10" woofer or something.. Are those speakers called 3 way speakers? I see "full range" is one loudspeaker that handles a full range of frequencies (just googled it) -- don't want that.
the speaker impedance determines the maximum voltage of transformer that the chip can use reliably.
If you use 8ohms speakers then you can use a 25+25Vac transformer, or even a little bit more, but not as high as 28+28Vac
4ohms speakers can allow use of a transformer up to about 22+22Vac, but I have never built one so that's based on what I read here.
6ohms speakers are a bit unusual. They would allow an intermediate transformer voltage.
But, some speaker manufacturers referred to their 4 to 8ohms speakers as 6ohms. This way of specifying a speaker impedance is misleading. Most of the power delivered to a conventional 2way speaker is sent to the bass/mid and if to get a flattish frequency response they have used a 4ohms bass/mid with an 8ohms treble then the amplifier is predominantly being loaded by the 4ohms driver.
The transformer should be selected to suit the 4ohms driver. Not to suit 6ohms.
If you use 8ohms speakers then you can use a 25+25Vac transformer, or even a little bit more, but not as high as 28+28Vac
4ohms speakers can allow use of a transformer up to about 22+22Vac, but I have never built one so that's based on what I read here.
6ohms speakers are a bit unusual. They would allow an intermediate transformer voltage.
But, some speaker manufacturers referred to their 4 to 8ohms speakers as 6ohms. This way of specifying a speaker impedance is misleading. Most of the power delivered to a conventional 2way speaker is sent to the bass/mid and if to get a flattish frequency response they have used a 4ohms bass/mid with an 8ohms treble then the amplifier is predominantly being loaded by the 4ohms driver.
The transformer should be selected to suit the 4ohms driver. Not to suit 6ohms.
That will work with 8ohms speakers and probably work with real 6ohms speakers.
It will work with 4ohms speakers but you will need a bigger heatsink and you must be carefull to never overload beyond what the chip can self protect from abuses.
A 4 to 8ohms speaker probably falls into the same category as the 4ohms. With care you may get away with it if you ensure the chip is never abused and is always kept cool.
No parties with drunken operators.
It will work with 4ohms speakers but you will need a bigger heatsink and you must be carefull to never overload beyond what the chip can self protect from abuses.
A 4 to 8ohms speaker probably falls into the same category as the 4ohms. With care you may get away with it if you ensure the chip is never abused and is always kept cool.
No parties with drunken operators.
What fun is that
I always thought that it should be designed to take a bit of a abuse.
I am using a few class "D" amps (TPA3100D2 & TPA3118) these days for most of my low power stuff and it is near impossible to blow them up. If you overload them all they do is distort basically or shutdown.
As for speakers
So many options. I have expensive Dynaudio Gemini and some that I got at a garage sale for 20 bucks, Altec Lansing model 3's. They both sound fine. I did tune up the model 3's with some morel mdt32s tweeters however, which made a really cheap speaker sound like a fine speaker.
For the outside speakers I am using the 6" coax speakers in a cheap plywood box. The only thing left of my old Ford F150 truck
I'd stick with 8 ohm nominal speakers, 6 ohm is fine too. Look around on craigs list or locally for old stuff but check the rubber surrounds as they tend to rot after 10-20 years.
I like to visit partsexpress and madisound for speaker ideas if you want something new or to refirb old stuff.
Have fun
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Only if the correct, or lower voltage, transformer is being used.What fun is that
I always thought that it should be designed to take a bit of a abuse...............
Where the transformer voltage is too high for the chip and speaker impedance combination, then some abuse may push it into destruction, or at least irresversible damage.
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