Hi,
I am trying to find a good value budget amplifier for a DIY multiroom audio project based on a Raspberry Pi, HifiBerry (Raspberry Pi specific DAC which takes I2S straight from the CPU) and Volumio (Linux distro designed purely for audio playback especially on the RPi).
Some Googling first led me to the Lepai LP-2020A+, a bit more Googling and reading this forum indicated that the Sure 2 X 15Watt Class D Audio Amplifier Board - TA2024 might be just as good (if not better) and cheaper. I have no problem with this not being in a case because I would eventually like to build it into either a case with everything in or into the wall.
I'm just looking for some guidance as to whether I am on the right lines or not with regards to this amp.
Links:
HiFiBerry | HiFi for the Raspberry Pi and more
Home - Volumio - audiophile music player
2 X 15Watt Class D Audio Amplifier Board - TA2024_Class D Amplifier Board_Audio Amplifier and other Audio Boards_Audio_Sure Electronics' Webstore
This is my first DIY audio project so any help would be very much appreciated.
I am trying to find a good value budget amplifier for a DIY multiroom audio project based on a Raspberry Pi, HifiBerry (Raspberry Pi specific DAC which takes I2S straight from the CPU) and Volumio (Linux distro designed purely for audio playback especially on the RPi).
Some Googling first led me to the Lepai LP-2020A+, a bit more Googling and reading this forum indicated that the Sure 2 X 15Watt Class D Audio Amplifier Board - TA2024 might be just as good (if not better) and cheaper. I have no problem with this not being in a case because I would eventually like to build it into either a case with everything in or into the wall.
I'm just looking for some guidance as to whether I am on the right lines or not with regards to this amp.
Links:
HiFiBerry | HiFi for the Raspberry Pi and more
Home - Volumio - audiophile music player
2 X 15Watt Class D Audio Amplifier Board - TA2024_Class D Amplifier Board_Audio Amplifier and other Audio Boards_Audio_Sure Electronics' Webstore
This is my first DIY audio project so any help would be very much appreciated.
Hey Jaycee, thank you for that tip, much appreciated.
Working on the assumption that this forum helps those who help themselves I have just spent 2 hours on Google looking into Gainclones and have, what I hope are constructive, questions.
I get the impression that this site is a good source for boards and they are made by an active member of DIY Audio:
LM3886 Amplifier Kits | Product Categories | Chipamp Electronics
Which led me to the question of which is better, the stereo kit or the mono kit? I get the impression that if you do it properly a mono kit is better, the reasons I found made a lot of sense. But then I found this sentence:
One rule of thumb I stand by (except on Gainclones.......they're just wierd) is to use the largest, most heavy duty power supply I can practically use.
From here: http://www.diyaudio.com/forums/solid-state/21925-dual-mono-vs-stereo.html (final post)
So just what is different about Gainclones? =S
The question I have is just wanting to check that I have interpreted things correctly, can this transformer be used with the kits linked above in the UK (230v)?
Toroidal Transformer 100VA | 120-235V-in | 2x25V-out | Velleman TR8040
Working on the assumption that this forum helps those who help themselves I have just spent 2 hours on Google looking into Gainclones and have, what I hope are constructive, questions.
I get the impression that this site is a good source for boards and they are made by an active member of DIY Audio:
LM3886 Amplifier Kits | Product Categories | Chipamp Electronics
Which led me to the question of which is better, the stereo kit or the mono kit? I get the impression that if you do it properly a mono kit is better, the reasons I found made a lot of sense. But then I found this sentence:
One rule of thumb I stand by (except on Gainclones.......they're just wierd) is to use the largest, most heavy duty power supply I can practically use.
From here: http://www.diyaudio.com/forums/solid-state/21925-dual-mono-vs-stereo.html (final post)
So just what is different about Gainclones? =S
The question I have is just wanting to check that I have interpreted things correctly, can this transformer be used with the kits linked above in the UK (230v)?
Toroidal Transformer 100VA | 120-235V-in | 2x25V-out | Velleman TR8040
A Gainclone is really just a term used for a power amplifier using the chips I mentioned. It stems from the 47 Labs "Gaincard" amplifier.
The stereo kit is just two mono amplifiers, plus a single power supply board. "Dual Mono" usually refers to two separate power supplies for each amp. Personally, I think that's unnecessary extravagance.
I'd personally recommend at least a 250VA transformer for stereo use. As long as the transformer primary matches your mains voltage, and it has 2x 25VAC secondaries, it will work.
Remember, you will need to mount the two LM3886 chips to a heatsink.
The stereo kit is just two mono amplifiers, plus a single power supply board. "Dual Mono" usually refers to two separate power supplies for each amp. Personally, I think that's unnecessary extravagance.
I'd personally recommend at least a 250VA transformer for stereo use. As long as the transformer primary matches your mains voltage, and it has 2x 25VAC secondaries, it will work.
Remember, you will need to mount the two LM3886 chips to a heatsink.
Even though I have many amps that use LM3886TF chips in my active three way speakers(and I do like them), they do need some skill in the assembly of electronics. Using a class D amp does remove a lot of work AND danger. While a chip amp MAY sound better (and I would be hard pressed to tell), it does require a lot more work and knowledge.
If you are comfortable with wiring mains voltage, by all means go with the LM chips. If, however, you aren't quite at home, the Class D amps offer a very good solution, without potentially killing ourself.
Abs
If you are comfortable with wiring mains voltage, by all means go with the LM chips. If, however, you aren't quite at home, the Class D amps offer a very good solution, without potentially killing ourself.
Abs
If you kill yourself building an amp then you should not do anything any time at all. Also don't know why class D any safer? Every amp is plugged into mains. As he linked kits, it will remove the most of knowledge part. So I would also go with gainclones.
About the linked kit. The dual mono has more supply caps. For lm3886 I would also suggest to go with the dual mono setup. You still can have 1 transformer. But the stereo kit has less capacitors. It is needed if you use the amp at higher volume. Also suggest at least 200VA-250VA trafo. 1 chips can handle 135W peak.
About the linked kit. The dual mono has more supply caps. For lm3886 I would also suggest to go with the dual mono setup. You still can have 1 transformer. But the stereo kit has less capacitors. It is needed if you use the amp at higher volume. Also suggest at least 200VA-250VA trafo. 1 chips can handle 135W peak.
I assume Abs is saying Class D is safer because the current being used is so much lower (it is in the chips I linked in my first post at least).
Would it be better to use two transformers in two separate chassis or one larger transformer? Looking at some of the builds I found having two separate systems seems like a good idea.
Would it be better to use two transformers in two separate chassis or one larger transformer? Looking at some of the builds I found having two separate systems seems like a good idea.
Well, 2 separate PSUs, and even 2 separate 1-channel chassis each with its own PSU are good in terms of signal separation between the channels, if you're looking for a really high quality and normally make sense for relatively high-power amplifiers. This reminded me Accuphase M60 amplifier - 27 Kg, 450W monoblocks. Ultimate amplification devices.
Accuphase M60
Looking at the options you memtion at the initial post, I would say, 2 transformers would be a little bit of an overkill...
Accuphase M60
Looking at the options you memtion at the initial post, I would say, 2 transformers would be a little bit of an overkill...
Yeah I think the Gainclone idea is quite a lot more excessive than I was looking for in the original post but having now looked into them I think I quite like them.
I'm still thinking of using a T amp for a low powered system (e.g. two small ceiling speakers in a bathroom) but I also rather like the idea of building a really good hifi from scratch, monoblock Gainclones seems like a pretty awesome start to such a project.
So in the interests of no half measures (within reason, I don't think I'm quite ready to go off and design my own circuit just yet), is monoblocks a good idea?
I'm still thinking of using a T amp for a low powered system (e.g. two small ceiling speakers in a bathroom) but I also rather like the idea of building a really good hifi from scratch, monoblock Gainclones seems like a pretty awesome start to such a project.
So in the interests of no half measures (within reason, I don't think I'm quite ready to go off and design my own circuit just yet), is monoblocks a good idea?
Awesome!
Now I'm just trying to work out which transformer to get. This instruction manual says that a 2x25VAC output "should work best for a wide variety of loads".
It also says that plenty of people have used 160VA transforms but that 220VA doesn't strain the transformer.
http://chipamp.com/docs/lm3886-manual.pdf
This project uses 1 160VA transformer for a small stereo amp.
Nanoo - DIY LM3875 IC Non-Inverting Chip Amplifier (Gainclone)
So my question is do I need two 220VA transformers or would two 160VA be good?
Specifically would two of these be good?
http://www.amazon.co.uk/Multicomp-M...qid=1388699186&sr=8-8&keywords=160VA+Toroidal
And then just how the hell do I work out what sort of speakers this will be able to drive?
Now I'm just trying to work out which transformer to get. This instruction manual says that a 2x25VAC output "should work best for a wide variety of loads".
It also says that plenty of people have used 160VA transforms but that 220VA doesn't strain the transformer.
http://chipamp.com/docs/lm3886-manual.pdf
This project uses 1 160VA transformer for a small stereo amp.
Nanoo - DIY LM3875 IC Non-Inverting Chip Amplifier (Gainclone)
So my question is do I need two 220VA transformers or would two 160VA be good?
Specifically would two of these be good?
http://www.amazon.co.uk/Multicomp-M...qid=1388699186&sr=8-8&keywords=160VA+Toroidal
And then just how the hell do I work out what sort of speakers this will be able to drive?
For 2 monoblocks, 2 160VA transformers will be enough.
The one at Amazon looks good. When you mount it to the chassis, make sure there is a rubber plate not only at the top, under the metal disc, but also at the bottom, between the transformer ant the chassis. It makes the build safer and reduces possible short-term vibration at the moment of power-on, when the big capacitors initially charge (may be the case evem with soft-start in place).
The one at Amazon looks good. When you mount it to the chassis, make sure there is a rubber plate not only at the top, under the metal disc, but also at the bottom, between the transformer ant the chassis. It makes the build safer and reduces possible short-term vibration at the moment of power-on, when the big capacitors initially charge (may be the case evem with soft-start in place).
That transformer will be fine. Incidentally "Multicomp" is a brand of CPC/Farnell - http://cpc.farnell.com - so you can buy direct from them.
160VA for a monoblock would be plenty. You can get by with that for a stereo amp too - in fact this is what's typically in a lot of hifi amps around the £200-300 mark.
The gainclone shouldn't have any problems driving typical speakers even down to 4 ohms. Make sure you've got a decent heatsink. I built mine using a 160mm wide, 75mm High, 25mm fin depth heatsink I got quite cheap on eBay, with quite thick fins, and in a stereo amp I could only just get it warm blasting into two 4 ohm car speakers.
edit: http://www.rapidonline.com/ is also a good supplier. They also stock a good range of fischer elektronik heatsinks which are perfect for making amps
160VA for a monoblock would be plenty. You can get by with that for a stereo amp too - in fact this is what's typically in a lot of hifi amps around the £200-300 mark.
The gainclone shouldn't have any problems driving typical speakers even down to 4 ohms. Make sure you've got a decent heatsink. I built mine using a 160mm wide, 75mm High, 25mm fin depth heatsink I got quite cheap on eBay, with quite thick fins, and in a stereo amp I could only just get it warm blasting into two 4 ohm car speakers.
edit: http://www.rapidonline.com/ is also a good supplier. They also stock a good range of fischer elektronik heatsinks which are perfect for making amps
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Right so that's the transformer and the kit sorted.
Is this the correct potentiometer?
1pcs Japan ALPS 27 type blue potentiometer 2 X 100K --Gear shaft | eBay
It's a lot cheaper than the one on the Chip amp page and doesn't come with a PCB (logic tells me that soldering the potentiometer directly into the circuit should be better for audio quality than going via a PCB). Alps Potentiometer + PCB for Volume Control | Chipamp Electronics
And this heatsink seems large enough, but in the interests of being sure.
100*69*36mm New HeatSink Aluminum for LED & Power IC Transistor Module PBC | eBay
I had seen ALPS potentiometers discussed already but I haven't come across ideas for either RCA or speaker cable connectors, any ideas which brands I should be looking at?
Is this the correct potentiometer?
1pcs Japan ALPS 27 type blue potentiometer 2 X 100K --Gear shaft | eBay
It's a lot cheaper than the one on the Chip amp page and doesn't come with a PCB (logic tells me that soldering the potentiometer directly into the circuit should be better for audio quality than going via a PCB). Alps Potentiometer + PCB for Volume Control | Chipamp Electronics
And this heatsink seems large enough, but in the interests of being sure.
100*69*36mm New HeatSink Aluminum for LED & Power IC Transistor Module PBC | eBay
I had seen ALPS potentiometers discussed already but I haven't come across ideas for either RCA or speaker cable connectors, any ideas which brands I should be looking at?
I just finished my Chip Amp and used boards from Chipamp.com I was really happy with the boards and would recommend them to any one. Here is a link to see some pictures of my completed amp.
http://www.diyaudio.com/forums/chip-amps/248524-my-new-chip-amp.html
Im only using a 1.8 amp transformer for BOTH channels right now and it's working great. I think I'm going to up grade it in the future, but for now it sounds good. The heat sink I'm using is way too big and it doesn't even get warm when at full volume. I could have used the original heat sink that came with the case, but I had the larger one laying around and wanted to put it to use.
I found a good source for amp parts such as heat sinks is to post a message on Craig's list for broken or un wanted stereo receivers. I have been able to pick up some nice ones for just a few dollars and pull out some nice heat sinks and transformers.
Also the chip amp says to use a 25K pot switch and your link is for a 100k pot switch which is a pretty big difference. I'm using a 50K because that was already in the case I bought, but if I were to buy one I would go with the one chip amp suggests and get a 25K. I did some searching and it was hard to find a 25K alps pot that was cheaper after shipping costs than what Chip amp is asking for his.
Good luck with the build, make sure to post lots of pictures.
Dale P.
http://www.diyaudio.com/forums/chip-amps/248524-my-new-chip-amp.html
Im only using a 1.8 amp transformer for BOTH channels right now and it's working great. I think I'm going to up grade it in the future, but for now it sounds good. The heat sink I'm using is way too big and it doesn't even get warm when at full volume. I could have used the original heat sink that came with the case, but I had the larger one laying around and wanted to put it to use.
I found a good source for amp parts such as heat sinks is to post a message on Craig's list for broken or un wanted stereo receivers. I have been able to pick up some nice ones for just a few dollars and pull out some nice heat sinks and transformers.
Also the chip amp says to use a 25K pot switch and your link is for a 100k pot switch which is a pretty big difference. I'm using a 50K because that was already in the case I bought, but if I were to buy one I would go with the one chip amp suggests and get a 25K. I did some searching and it was hard to find a 25K alps pot that was cheaper after shipping costs than what Chip amp is asking for his.
Good luck with the build, make sure to post lots of pictures.
Dale P.
Awesome, is that green PCB which is connected to the outputs and the silver heatsink just there to power the LED UV meter? I thought you could just connect the inputs and outputs straight to the amp's PCB, is that wrong? If I'm not using a UV meter of any kind do I need to attach anything else to the heat sink or is it just the amp itself?
That's a cunning plan for sourcing components, I might just give it a go.
Ah I see what you mean, the manual says to get a 25K pot and yet the pot for sale on their website is a 100K pot. Should I go with the manual or the one they offer for sale?
Thank you, I will
That's a cunning plan for sourcing components, I might just give it a go.
Ah I see what you mean, the manual says to get a 25K pot and yet the pot for sale on their website is a 100K pot. Should I go with the manual or the one they offer for sale?
Thank you, I will
The circuit with the silver heatsink is the original amplifier that was in the case, which he's removed and discarded (just as well, judging by the look of the circuit!)
The main important thing is that the volume pot is logarithmic. The resistance value is a tradeoff between input impedance and noise. Higher impedance values are easier for a source to drive, but have higher noise (due to "Johnson Noise").
47K is the "de facto" standard for input impedance so often a 47K or 50K potentiometer is used. Modern sources will be fine driving as low as 22K.
Rapid have a 50K ALPS pot, if you are ordering parts from them. The Piher 47K Log pots they sell are also good. I've also used their Omeg 16mm pots with good results.
The main important thing is that the volume pot is logarithmic. The resistance value is a tradeoff between input impedance and noise. Higher impedance values are easier for a source to drive, but have higher noise (due to "Johnson Noise").
47K is the "de facto" standard for input impedance so often a 47K or 50K potentiometer is used. Modern sources will be fine driving as low as 22K.
Rapid have a 50K ALPS pot, if you are ordering parts from them. The Piher 47K Log pots they sell are also good. I've also used their Omeg 16mm pots with good results.
So the lower the number the better the audio quality but the more energy it takes to push the signal through the resistor?
Given I'm planning on using such large transformers for each block would it not give me better quality to use higher resistance pots? I'd like to build some valve preamps at some point down the line for volume and source selection (as well as experimenting with the valve sound) so I'm not so worried about it being hard to drive.
Given I'm planning on using such large transformers for each block would it not give me better quality to use higher resistance pots? I'd like to build some valve preamps at some point down the line for volume and source selection (as well as experimenting with the valve sound) so I'm not so worried about it being hard to drive.
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