lol. Coincidentally I inquired about the LM4780 boards last night. I have been out of the diy game for some time and missed out completely. They were discontinued before I knew of their existence.
The 3886DR and parallel projects look interesting so I plan to pay attention.
That's great. Where are they planning to get the LM4780 from? If it is not available from a distributor, I can't support the project. I'm not willing to lead people to eBay and deal with the "is this IC fake" support calls. Also, where were all these people during the first nine months of the Parallel-86 project? It was a very, very slow seller until TI decided to discontinue the IC.
Tom
Tom
Are you volunteering to organize one? If you order at least 12 boards, I'll be happy to make another board run. I'll give you 5 % off for the order of 12 boards and 15 % off if you order 20 or more boards. Please contact me via email (through my website) or PM if this works for you.
Tom
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According to TI, the only distributor options available are Newark/Farnell and EBV Elektronik. Both are in Europe. Newark sources from their UK stock, which means two LM4780s will set you back about $50.
Tom
It sounds like I should just bite the bullet for the Modulus-86. I don't plan on making a serious hobby of amp making. I just want to make the one and listen to my Britney and Astake records. It looks like the Modulus-86 is offered as PCBs and then a link to Mouser to get the parts for it rather than a nice neat package of all parts. Also, the PCB prices are "high" because it isn't really the PCB but the price of the PCB + all the work gone into making the design; something I'm totally into paying for.
I still have to figure out my pre-amp needs. Something for volume control and a couple input selections. I think that the Differential preamp is a little more than I need.
Also. I'm touched to have my first thread hijacked. It feels nice to use a forum again.
Correct. Should you get stuck during the build process, I'm always available on email to get you unstuck. That's worth something as well.
Yeah, less will certainly do it. If you need my input, just toss me an email via the Contact Us form on my website. I'll be happy to help out.
Also. I'm touched to have my first thread hijacked. It feels nice to use a forum again.
Sorry...
Yeah, it's still a forum.Tom
I've opened up for pre-orders of the LM3886DR board. I expect to be able to ship the boards around the middle of next week, assuming Canada Post does not go on strike. You can find the LM3886DR here: LM3886 Done Right
Tom
Tom
Did you ever get a chance to run the LM3886 off the SMPS300RE and take some measurements?5 V @ 6 A -> 30 W dissipated. Yep. That'll heat things up. The laws of physics are rather inconvenient that way.
My HP6643A works very well...
I plan to measure the LM3886DR with a Connex SMPS300RE. I suspect some switching noise may filter through, but we'll see. I'm planning to show a plot of the THD+N of the LM3886DR powered by two HP6643A lab supplies, a regular linear unregulated supply, and the Connex SMPS300RE. I need the boards to arrive first, though. They went into production yesterday.
Tom
Pre-amp help
Hello again!
After buying and assembling my pair of Modulus 86s I've been musing on my pre-amp for too long. I've done a lot of reading and a little bit of understanding. Now I've got either a good plan, way too much scope creep, or both!
Attached is a pseudo schematic for my idea.
I realize that all my sources will be single ended. So, I've selected ICs that handle single ended signals. I'm using a pair of MPC508As for switching between signals. From there I'm going to a PGA2310 or PGA2311 for digital volume control. From there I am going to use a pseudo differential signal and connect to a THAT 1606s to buffer the output before sending the signal my Modulus 86s.
Two of my inputs will be internal to my design. One FM reciever & one bluetooth reciever.
Blue tooth: Sure Electronics' webstore Bluetooth V4.0 Audio Receiver Board w APT-X - BRB3
I'm considering this Bluetooth reciever. It's not the highest end receiver, but will do for my purposes. It will need 9-15V (12V typical)
FM Receiver: https://www.sparkfun.com/products/11083
Both the input switching and the volume control will be controlled by an arduino. The arduino will interpret signals from a set of capacitance touch buttons and a rotary encoder.
Open questions
Power: I currently have an SMPS-86 from Tom @ Neurochrome. It provides +-24V for the Modulus-86s.
I think after evaluating my needs, I'll need a second power supply. As I understand it, I'll need +-15V for the PGA2310 and the MPC508A. The Arduino runs on 5V and has a internal regulator to handle 7-12V recommended or 6-20V min/max. A few internet sources say that above 12V for too long is bad, so I'd prefer to have a 12V rail for it. It can produce a regulated 5V and 3.3V(used in the FM receiver & the cap Sense). The neopixels need 5V+ and will draw about 400mA. This is within the ability of the arduino to provide(500mA - 1A) but I'm not sure I love it(https://www.youtube.com/watch?v=6-_AgqpjOiU). So, how can I use a +-15V source like the meanwell RS-25-15(http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkeyRS-25-15) to also provide the 12V DC for the Bluetooth receiver & the Arduino and the 5V DC that I need for the neopixels. If I use the 15V+ to ground with some voltage regulator will it be a problem?
PGA2310 or PGA2311: The main difference for me is the operating voltage. 5 vs 15. Some suggest having the 15V version provides better "headroom", but I don't really understand the implications of this. http://www.diyaudio.com/forums/chip-amps/115684-pga2310-vs-pga2320.html
I suppose that if I'm already going to need +-15V for the MPC508A, I might as well use the PGA2310.
THAT1606 & source/load impedances: Is this the right place to use these? Everywhere I look I see that having a low impedance source for the power amp is the preferable solution. When I suggested I was going to use an ALPs pot as the attenuator, I got the feedback that it would be a good idea to buffer the output. It looks like the PGA231x would be a low impedance source, so maybe this part is uncessary. Perhaps they are necessary between other stages?
Alternatives to the MPC508As: The MPC508A switches mono single ended signals. I looked at other chips in the family, but they all seemed to switch mono sources (either single ended or differential). Does anyone know any suitable chips that would switch both left and right with a single chip?
Datasheet Links:
MPC508A: http://www.ti.com/lit/ds/symlink/mpc508.pdf
PGA2310: PGA2310 | Volume Control | Audio | Description & parametrics
PGA2311: PGA2311 | Volume Control | Audio | Description & parametrics
Neopixel power : https://learn.adafruit.com/adafruit-neopixel-uberguide/power
Hello again!
After buying and assembling my pair of Modulus 86s I've been musing on my pre-amp for too long. I've done a lot of reading and a little bit of understanding. Now I've got either a good plan, way too much scope creep, or both!
Attached is a pseudo schematic for my idea.
I realize that all my sources will be single ended. So, I've selected ICs that handle single ended signals. I'm using a pair of MPC508As for switching between signals. From there I'm going to a PGA2310 or PGA2311 for digital volume control. From there I am going to use a pseudo differential signal and connect to a THAT 1606s to buffer the output before sending the signal my Modulus 86s.
Two of my inputs will be internal to my design. One FM reciever & one bluetooth reciever.
Blue tooth: Sure Electronics' webstore Bluetooth V4.0 Audio Receiver Board w APT-X - BRB3
I'm considering this Bluetooth reciever. It's not the highest end receiver, but will do for my purposes. It will need 9-15V (12V typical)
FM Receiver: https://www.sparkfun.com/products/11083
Both the input switching and the volume control will be controlled by an arduino. The arduino will interpret signals from a set of capacitance touch buttons and a rotary encoder.
Open questions
Power: I currently have an SMPS-86 from Tom @ Neurochrome. It provides +-24V for the Modulus-86s.
I think after evaluating my needs, I'll need a second power supply. As I understand it, I'll need +-15V for the PGA2310 and the MPC508A. The Arduino runs on 5V and has a internal regulator to handle 7-12V recommended or 6-20V min/max. A few internet sources say that above 12V for too long is bad, so I'd prefer to have a 12V rail for it. It can produce a regulated 5V and 3.3V(used in the FM receiver & the cap Sense). The neopixels need 5V+ and will draw about 400mA. This is within the ability of the arduino to provide(500mA - 1A) but I'm not sure I love it(https://www.youtube.com/watch?v=6-_AgqpjOiU). So, how can I use a +-15V source like the meanwell RS-25-15(http://www.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkeyRS-25-15) to also provide the 12V DC for the Bluetooth receiver & the Arduino and the 5V DC that I need for the neopixels. If I use the 15V+ to ground with some voltage regulator will it be a problem?
PGA2310 or PGA2311: The main difference for me is the operating voltage. 5 vs 15. Some suggest having the 15V version provides better "headroom", but I don't really understand the implications of this. http://www.diyaudio.com/forums/chip-amps/115684-pga2310-vs-pga2320.html
I suppose that if I'm already going to need +-15V for the MPC508A, I might as well use the PGA2310.
THAT1606 & source/load impedances: Is this the right place to use these? Everywhere I look I see that having a low impedance source for the power amp is the preferable solution. When I suggested I was going to use an ALPs pot as the attenuator, I got the feedback that it would be a good idea to buffer the output. It looks like the PGA231x would be a low impedance source, so maybe this part is uncessary. Perhaps they are necessary between other stages?
Alternatives to the MPC508As: The MPC508A switches mono single ended signals. I looked at other chips in the family, but they all seemed to switch mono sources (either single ended or differential). Does anyone know any suitable chips that would switch both left and right with a single chip?
Datasheet Links:
MPC508A: http://www.ti.com/lit/ds/symlink/mpc508.pdf
PGA2310: PGA2310 | Volume Control | Audio | Description & parametrics
PGA2311: PGA2311 | Volume Control | Audio | Description & parametrics
Neopixel power : https://learn.adafruit.com/adafruit-neopixel-uberguide/power
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