Yes, 0.35C/W is huge.
I use the National (Ti) datasheet for the lm3886 and then double it to keep the chip cool and less likley to trigger any temperature dependanrt protections.
For two chips that amounts to a quadrupling of the National guidance, but still far smaller than 0.35C/W for most arrangements.
215x77x130 mm gives you 0.322 from this heatsink:
Heatsinks: 1000 Series - 1670HS | BAL Group Ltd
That's an acceptable size for me
Heatsinks: 1000 Series - 1670HS | BAL Group Ltd
That's an acceptable size for me
The Modulus-286 in MONO configuration is thermally identical to a Parallel-86. For the Modulus-286, I did the math in a bit more depth to see if I could ease up on the heat sink requirements a bit. Here's how the numbers fell out:
Parallel-86/Modulus-286 MONO @ ±35 V: 0.6 K/W (4 Ω); 1.0 K/W (8 Ω), both assuming music signal, 25 ºC ambient, 60 ºC heat sink.
A larger heat sink (lower thermal resistance) will never hurt (other than perhaps your wallet).
The heat sinks on the BZ4309 eBay chassis I used for my 4xMOD86 amp have a thermal resistance of around 0.3 K/W when attached to the (quite thick) top, bottom, front, rear panels.
The heat sinks in the ModuShop/DIY Audio Store Dissipante 2U, I estimate to be about 0.5 K/W. They'll be fine for music signal, but too small for two channels of Modulus-286 to be powering a 4 Ω load with a sine wave at the worst case thermal dissipation. This based on the 2xMOD286 amp I built back in December and stuffed into that chassis.
Tom
Parallel-86/Modulus-286 MONO @ ±35 V: 0.6 K/W (4 Ω); 1.0 K/W (8 Ω), both assuming music signal, 25 ºC ambient, 60 ºC heat sink.
A larger heat sink (lower thermal resistance) will never hurt (other than perhaps your wallet).
The heat sinks on the BZ4309 eBay chassis I used for my 4xMOD86 amp have a thermal resistance of around 0.3 K/W when attached to the (quite thick) top, bottom, front, rear panels.
The heat sinks in the ModuShop/DIY Audio Store Dissipante 2U, I estimate to be about 0.5 K/W. They'll be fine for music signal, but too small for two channels of Modulus-286 to be powering a 4 Ω load with a sine wave at the worst case thermal dissipation. This based on the 2xMOD286 amp I built back in December and stuffed into that chassis.
Tom
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Hey Tom,
I've been listening to my four channels of Mod86 to my bi-amped speakers for almost a year now. They still run cool and quiet with no problems. They brought me a new level of enjoyment in listening to my favorite songs.
I'm thinking of building two more channels of Mod86. I added Dave's Sub to my LX Minis, and it would be cool if all 6 of my amp channels match.
Do you still have any of the previous version boards that use the old rectangular LME47xxx (whatever it is called)? I had gotten a few extra of those parts when they were going out of production. It's cool that you revised the board a little to take the round version, just wondered if you have a couple of the older ones.
Cheers,
I've been listening to my four channels of Mod86 to my bi-amped speakers for almost a year now. They still run cool and quiet with no problems. They brought me a new level of enjoyment in listening to my favorite songs.
I'm thinking of building two more channels of Mod86. I added Dave's Sub to my LX Minis, and it would be cool if all 6 of my amp channels match.
Do you still have any of the previous version boards that use the old rectangular LME47xxx (whatever it is called)? I had gotten a few extra of those parts when they were going out of production. It's cool that you revised the board a little to take the round version, just wondered if you have a couple of the older ones.
Cheers,
I'm surprised at the small size for BAL @ 0.322 C/W, compared to the heatsinkusa size @ 0.40 C/W.
BAL Group C/W rating is based on 60C temp. rise, while heatsinkusa C/W rating is based on 70C temp. rise.
Also Bal Group heatsink is black anodized while the heatsinkusa is not anodized or treated in any way.
Are the different temp. rise above ambient values and black anodizing the main reason for the difference?
I ask because I'm ready to order heatsinks for my Parallel 86 and was only going for two .9 C/W heatsinks. Seems I might be able to get smaller ones, or just one, with lower C/W from BAL Group. Have you gotten their prices?
Thanks,
henrylyjr
Henry
I've requested a price from them. Will post the answer. I think the problem for you will be the cost of shipping to the USA.
I've requested a price from them. Will post the answer. I think the problem for you will be the cost of shipping to the USA.
The DIYAudio store has a page with their heatsink specifications here: https://diyaudiostore.com/pages/40mm-heatsink-information. It depends whether they're 300 mm deep or 400 mm deep (2 x 200mm).
I don't have any Rev. 2.0 boards left. Only 2.1 boards.
TI discontinued the DIP version for a few months. Long enough that I ran out of boards and switched out the footprint. About two weeks after I got my stack of boards from the manufacturer, TI decided to bring the DIP version back. While I'm glad they did, it was rather crappy timing. Oh, well.
Some builders have trouble with the TO-99 metal can package. On the TO-99, pin 8 is marked by a tab. Every other package has pin 1 marked, so a common mistake is to be off by one pin when stuffing the chip. It's quite hard to de-solder, so tears have been shed and frustration expressed in email. Thus, Rev. 2.2 will switch back to the DIP footprint. It'll also be blue and feature my new logo. I'll also adjust the price for inflation. I'm not planning any circuit changes as I can't come up with any changes that'll make a meaningful difference using only leaded components. I have a couple of months' worth of inventory of Rev. 2.1 left, so Rev. 2.2 is some ways out.
Tom
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Thanks for the heads up about the pin 8 marked ona TO-99.
I'll order from your website soon.
I go through the math on my website: https://www.neurochrome.com/taming-the-lm3886-chip-amplifier/thermal-design/#TempLengthCorrection
All you have to do is to read the compensation factor from a table.
Tom
Hi Tom,
As usual, you have the answer! It's no wonder why so many love your amps and working with you.
As usual, you have the answer! It's no wonder why so many love your amps and working with you.
Thus, Rev. 2.2 will switch back to the DIP footprint. It'll also be blue and feature my new logo. I'll also adjust the price for inflation. I'm not planning any circuit changes as I can't come up with any changes that'll make a meaningful difference using only leaded components. I have a couple of months' worth of inventory of Rev. 2.1 left, so Rev. 2.2 is some ways out.
Tom[/QUOTE]
When do u plan to have the rev2.2 boards ready?
Tom[/QUOTE]
When do u plan to have the rev2.2 boards ready?
Folks,
I have one last survey request. This is for my Consumer Psychology class. I would greatly appreciate it if you'd spend about 15 minutes answering a few questions about a handful of Google ads and Facebook ads ("suggested posts") for me by taking this survey: https://ucalgarypsych.co1.qualtrics.com/jfe/form/SV_9Ys8lFknxxawAYJ
Thank you. I really appreciate it.
Tom
I have one last survey request. This is for my Consumer Psychology class. I would greatly appreciate it if you'd spend about 15 minutes answering a few questions about a handful of Google ads and Facebook ads ("suggested posts") for me by taking this survey: https://ucalgarypsych.co1.qualtrics.com/jfe/form/SV_9Ys8lFknxxawAYJ
Thank you. I really appreciate it.
Tom
Within a week or two of running out of Rev. 2.1 boards. So probably sometime towards the end of summer based on the current run-rate and inventory stack.
Note that Rev. 2.1 and 2.2 will be the same circuit, just a different footprint for one IC to make assembly easier.
Tom
Just took the survey. The section where you have 6 ads to rank in order of preference looks unfinished in that there's no instruction what to do and some 'boilerplate' text right at the top. Also you're asking questions about support and also ease of purchase on your website even though I believe there was a question earlier on if you've ever made a purchase. I clicked 'no' on that but still was given questions about support quality and ease of navigation of neurochrome.com for purchases.
Cool. Thanks.
Odd. I'll look into it.
DOH! That wasn't supposed to happen. I did specify to my survey editor that a no response should just end the survey. It must have slipped and I didn't catch it. My bad. We're in pretty hard crunch time mode here. Not due to lack of effort. Just the usual end-of-term thing.
Thanks for your time and feedback. I guess we now know that the precision of my circuits exceed that of my surveys. 😀
Tom
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Price for 130mm width is £34.52. That includes UK delivery but not VAT, which you wouldn't have to pay on exports to the USA. Delivery would obviously be more though . . .
For the US, Heatsink USA is likely your better option. Unfortunately, their profiles are shiny, not anodized, so they're not as efficient as they could be. They're nice profiles, though. If you want them anodized, you can always get that done locally.
I used to build my own enclosures. Now I find myself rather strongly attracted by the ModuShop/DIY Audio Store enclosures. They could be a little bit nicer (like countersunk screws on the top plate) but man... you get a lot for your money there and the heat sinks are nice and large.
Tom
I used to build my own enclosures. Now I find myself rather strongly attracted by the ModuShop/DIY Audio Store enclosures. They could be a little bit nicer (like countersunk screws on the top plate) but man... you get a lot for your money there and the heat sinks are nice and large.
Tom