An audio ground is an audio ground. It is always not recommended to connect audio ground and chassis ground which may be connected to earth! The earth of the electrical circuit must still be good...
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https://www.parts-express.com/Dayto...rd-with-Tone-and-Volume-Co-325-501?quantity=1
Not eBay or Aliexpress
But under 50$
Sold by a trusted etailer.
Not eBay or Aliexpress
But under 50$
Sold by a trusted etailer.
This one is the same board, before it was made Bluetooth. As the one with Bluetooth seems to have noise problems, it should be better if you don't need, which is a little cheaper as well.
The thing to notice: You can (don't need to!) drive it with a symetric signal. Seems to be the only cheap board with this feature.
It is marketed as Wondom/ Sure board too.
https://de.aliexpress.com/item/1005....0.0.6d3a4ae4iOKS6O&mp=1&gatewayAdapt=glo2deu
The thing to notice: You can (don't need to!) drive it with a symetric signal. Seems to be the only cheap board with this feature.
It is marketed as Wondom/ Sure board too.
https://de.aliexpress.com/item/1005....0.0.6d3a4ae4iOKS6O&mp=1&gatewayAdapt=glo2deu
I meant on bare (no volume or tone controls) TPA3255 board.
Does adding passive preamp like this one degrade the sound by large margin?
Is active preamp better idea?
Does adding passive preamp like this one degrade the sound by large margin?
Is active preamp better idea?
Do you listen to Radio Eriwan? "Yes it degrades sound quality, but if you need the bass/ tremble for better sound, it is the opposite."
Personally I prefer an amp with a reasonable input sensitivity and no pots at all. The are always a cause for trouble.
Let the preamp do the work. Done right it has a buffer on the input and output, if there has to be a tone controll, you should be able to switch it of.
Those "passive preamps" can work if the input signal is strong enough and the main amp has an input buffer.
Maybe change the speakers if they need a bend signal to sound right.
Personally I prefer an amp with a reasonable input sensitivity and no pots at all. The are always a cause for trouble.
Let the preamp do the work. Done right it has a buffer on the input and output, if there has to be a tone controll, you should be able to switch it of.
Those "passive preamps" can work if the input signal is strong enough and the main amp has an input buffer.
Maybe change the speakers if they need a bend signal to sound right.
Maybe I should describe context in more detail. It is an instrument/guitar amp - more akin to a PA box. Treble and bass are welcome options when you have to tailor sound to different rooms/clubs/venues ... where amp is sitting. Tone controls are not necessary, but the volume pot is. I would like to keep it simple ... and small ... it will be very compact.
Line input --to-- active preamp module or passive volume control --to-- TPA amp module --to-- full range speakers ... with power supply in the box.
Line input --to-- active preamp module or passive volume control --to-- TPA amp module --to-- full range speakers ... with power supply in the box.
OK, that is a different thing. You need some option to adjust sound. I have no idea how such a construction should work.
Maybe look for a preamp made for this. Instruments have very different output impedance compared to Hifi. Why don't you integrate something like this in your build? https://www.aliexpress.com/item/1005006326421017.html
If you need an instrument pre, better use one.
For use with instruments the symetric input of this board is a huge advantage. You need to use a decend power supply, at least 48 Volt 10A to have enough clean headroom for short peaks, even if you play not very loud on average.
The distortion of an A/B or D amp is nothing you want in your case (the desired distortion is from valves only!).
Maybe look for a preamp made for this. Instruments have very different output impedance compared to Hifi. Why don't you integrate something like this in your build? https://www.aliexpress.com/item/1005006326421017.html
If you need an instrument pre, better use one.
For use with instruments the symetric input of this board is a huge advantage. You need to use a decend power supply, at least 48 Volt 10A to have enough clean headroom for short peaks, even if you play not very loud on average.
The distortion of an A/B or D amp is nothing you want in your case (the desired distortion is from valves only!).
That's conventional wisdom for a portion of the audio community, but my own theory is that this notion of keeping AGD and earth separate on an amplifier is linked to the apprehension that some other device in a user's (unbalanced) audio chain may have its AGD connected to earth - and of course this will result in a ground loop. But the counterpoint to this argument is -
it's OK (even beneficial) to have AGD connected to earth in an unbalanced system, provided it's only done at one device in the chain.
It's my preference (encouraged by other members of this forum) to have this AGD-to-earth connection at the amplifier, all other devices in my chain to have floating GND.
So how does Texas Instruments feel about this matter? The TPA3255 evaluation module (which I purchased in 2018) comes supplied with 5x metal standoffs (image attached) for which TI obviously wants the end-user to mount to the chassis. And guess what - all 5 standoffs make contact with the circuit board's GND plane.
Attachments
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... and better look for class A on the headphone output and analog split supply, that is no DC-DC power supply. Even if fed by batteries.
Hello everyone, this is my first post here.
This is about an issue with my first DIY audio project.
I read through a lot of pages in this thread and a similar one on the TPA3255.
It is amazing and impressive to see what everyone is working on and hopefully I'm right here with my newbie project.
I'm currently trying to fix an all-in-one 2.1 speaker.
The internal receiver/amplifier board is broken - so I was gifted the speaker to try and repair it with something new.
My idea was to order an amplifier board which fits into the slot of the broken one.
After reading a few good things about the TPA3255 online I ordered a chinese 2.1 amplifier board with the chip.
The exact listing no longer exists, but there is exactly the same board here.
As I'm mostly clueless I hoped someone in this forum might know what problem I have here.
With or without a source connected, the speakers make a very weird noise. I never heard anything like this.
I made a short video of the setup here. Turn up the volume and you can hear the weird sound.
The only thing I really did so far is to solder some terminal blocks to the board's empty holes so I could connect the speaker/subwoofer cables.
Speaker impedance matches the board - 4 ohms.
I tested the board with two different 48V 5A power supplies, both are from other audio equipment, one is grounded, the other one ungrounded.
The noise is a bit better with the ungrounded one.
I would very much appreciate any hint what the issue here is or how I could approach this.
Thank you very much!
This is about an issue with my first DIY audio project.
I read through a lot of pages in this thread and a similar one on the TPA3255.
It is amazing and impressive to see what everyone is working on and hopefully I'm right here with my newbie project.
I'm currently trying to fix an all-in-one 2.1 speaker.
The internal receiver/amplifier board is broken - so I was gifted the speaker to try and repair it with something new.
My idea was to order an amplifier board which fits into the slot of the broken one.
After reading a few good things about the TPA3255 online I ordered a chinese 2.1 amplifier board with the chip.
The exact listing no longer exists, but there is exactly the same board here.
As I'm mostly clueless I hoped someone in this forum might know what problem I have here.
With or without a source connected, the speakers make a very weird noise. I never heard anything like this.
I made a short video of the setup here. Turn up the volume and you can hear the weird sound.
The only thing I really did so far is to solder some terminal blocks to the board's empty holes so I could connect the speaker/subwoofer cables.
Speaker impedance matches the board - 4 ohms.
I tested the board with two different 48V 5A power supplies, both are from other audio equipment, one is grounded, the other one ungrounded.
The noise is a bit better with the ungrounded one.
I would very much appreciate any hint what the issue here is or how I could approach this.
Thank you very much!
I'm currently trying to fine a 48V external power supply for use (probably) with some 3E mono TPA3255 boards - it needs to have an RCM electrical safety compliance mark for Australia/NZ though. The last bit seems surprisingly difficult - most of the chinese adapters seem to have CE compliance and maybe UK or US compliance but no RCM. I guess that makes sense due to our small local market.
I was looking at some of the meanwell products - is this one single supply and suitable for these boards? https://au.mouser.com/ProductDetail/MEAN-WELL/GST360A48-C6P?qs=rSMjJ%2B1ewcT%2BWQ0Ja8HtVA==&utm_id=10903657381&gad_source=1&gclid=Cj0KCQjwv7O0BhDwARIsAC0sjWM2OCOYnHgZ7lHm_66AAN7cWwEoz_VIgR8pjcI1iCCNFi4EkWpaK1AaAtb2EALw_wcB
I was looking at some of the meanwell products - is this one single supply and suitable for these boards? https://au.mouser.com/ProductDetail/MEAN-WELL/GST360A48-C6P?qs=rSMjJ%2B1ewcT%2BWQ0Ja8HtVA==&utm_id=10903657381&gad_source=1&gclid=Cj0KCQjwv7O0BhDwARIsAC0sjWM2OCOYnHgZ7lHm_66AAN7cWwEoz_VIgR8pjcI1iCCNFi4EkWpaK1AaAtb2EALw_wcB