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Old 6th April 2010, 10:52 PM   #1271
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Thanks Sendler, but will be will stay put with the 24v, at 14amps that should be ample I think. Also I am biamping, so having bought 2x 24v Meanwells would be costly to replace !
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Old 7th April 2010, 04:26 AM   #1272
v-bro is offline v-bro  Netherlands
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Quote:
Originally Posted by Drakmin View Post
I ran the amp only one speaker connected since I don't know what a dummyload is. About the fan I remove it now. Maybe 2x100 requires a fan but I need max 1x40 so my heat prodction should be less than a fourth?
This is not a conventional amplifier, this amplifier is ALWAYS switching. The difference between running at full output or at idle is fairly little. I have seen T-amps that run hotter at idle than at full output...
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Old 7th April 2010, 04:35 AM   #1273
v-bro is offline v-bro  Netherlands
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Originally Posted by thierry38efd View Post

noise is comming from the fan ,it's obvious
the best and easy way is to connect the fan ground dirctely to the 0 V supply.to avoid common impedance.
Connecting it elsewhere will not block the emission, this is not guaranteed to get rid of the noise. Your passive solution is rather sound though, not very elegant, but if it works it works...

But, what on earth did you place on the outputs? Are those gigantic zobels? Why?
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Old 7th April 2010, 03:42 PM   #1274
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Originally Posted by sendler View Post
The 4 channel amp is worse in reliability because the heat sink doesn't contact the chips well and the dc off set adjustment circuit doesn't give enough range of adjustment without a mod to jump some resistors. I would rather have the other, 2 channel board without the crazy piggyback output board but it looks like Sure is determined to get rid of the 4 channel boards. If the dc can't be adjusted to less than 5mv per leg, tell Sure you demand the other board.
Scott, with all due respect to the contributions you've made to the forum, I feel you're being a little hard on the 4 channel amp. First, the 8 surface mount resistors surrounding the 4 DC offset trim pots can be fixed in about 5 minutes, by unscrewing the heat sink, then painting them over with a small paintbrush dipped in conductive paint. Second, surely we can devise some better heat sink solution, I mean how hard can it be compared to prying out the inductors, and replacing them with hand-wound inductors for example?

Anyway I wanted to talk about batteries. I have a line on some novel Lithium Iron batteries (LFP-NCO) (see here)that I'm guessing may be worth testing out as an alternative to SLA batteries. Because they have a discharge c-rate of perhaps 4, I'm guessing that they could deliver power effortlessly and that this would improve the sound. Do you think it would be worth trying, string 8 10mAh cells together to hold 80mAh and provide 26.4V. I suppose the board wouldn't draw 320 amps, but my intuition is having it available for transients can't be a bad thing. Plus FWIW these batteries are more eco-friendly than having lead and acid in your house even if its sealed.

Last edited by temp123456; 7th April 2010 at 03:55 PM.
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Old 7th April 2010, 04:05 PM   #1275
wwenze is offline wwenze  Singapore
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Talking about cooling for the 4-channel board, when trying to cool multiple components with a single big heatsink thermal pads between each component and the heatsink are recommended to avoid bad contact.
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Old 7th April 2010, 04:58 PM   #1276
sendler is offline sendler  United States
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Originally Posted by temp123456 View Post
Scott, with all due respect to the contributions you've made to the forum, I feel you're being a little hard on the 4 channel amp. First, the 8 surface mount resistors surrounding the 4 DC offset trim pots can be fixed in about 5 minutes, by unscrewing the heat sink, then painting them over with a small paintbrush dipped in conductive paint. Second, surely we can devise some better heat sink solution, I mean how hard can it be compared to prying out the inductors, and replacing them with hand-wound inductors for example?

Anyway I wanted to talk about batteries. I have a line on some novel Lithium Iron batteries (LFP-NCO) (see here)that I'm guessing may be worth testing out as an alternative to SLA batteries. Because they have a discharge c-rate of perhaps 4, I'm guessing that they could deliver power effortlessly and that this would improve the sound. Do you think it would be worth trying, string 8 10mAh cells together to hold 80mAh and provide 26.4V. I suppose the board wouldn't draw 320 amps, but my intuition is having it available for transients can't be a bad thing. Plus FWIW these batteries are more eco-friendly than having lead and acid in your house even if its sealed.
Sure arbitrarily substituted a 4 channel board with two channels disabled so they wouldn't just immediatley burn up without telling him after he ordered from a listing with a picture of the two channel board with the fan. Very devious. I personally have 13 of the fanned type amps and wouldn't want any of the 4 channel boards.
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Did you miss type the 80mAh rating? AA NiMh cells have 2200mAh each. An 80mAh battery will only last 15 minutes powering the amp. 10Ah would be enough capacity between over night charges. Battery power is a slight improvement over a MeanWell SMPS but for me it is not enough of difference to bother with.
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Old 8th April 2010, 01:51 AM   #1277
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Quote:
Originally Posted by sendler View Post
Sure arbitrarily substituted a 4 channel board with two channels disabled so they wouldn't just immediatley burn up without telling him after he ordered from a listing with a picture of the two channel board with the fan. Very devious. I personally have 13 of the fanned type amps and wouldn't want any of the 4 channel boards.
.
Did you miss type the 80mAh rating? AA NiMh cells have 2200mAh each. An 80mAh battery will only last 15 minutes powering the amp. 10Ah would be enough capacity between over night charges. Battery power is a slight improvement over a MeanWell SMPS but for me it is not enough of difference to bother with.
I didnt' realize Sure was doing that. I meant the 4 channel board ordered as a 4 channel board and delivering 4 channels. I use it to bi-amp my speakers. Though I agree setups where a 2 channel board is mounted right on the back of the speaker are nice.

I did miss something in my haste, the batteries are 10Ah, not mAh! That is going to be overkill. I should try their 40g 1.7Ah (1700mAh) cells instead.

But my larger question is if anyone thinks the C-rate will help the sound. They have a C-rate of 4; not sure what the C-rate is for SLA but its less than 1. I had to look it up here http://www.valence.com/technology/glossary "C-rate – A notation of current magnitude, expressed relative to the time required to discharge the rated discharge charge capacity of a cell or battery. A 1C rate corresponds to a current magnitude that would discharge the rated discharge charge capacity in 1/1 hour. A 2C rate would correspond to a current magnitude twice that of the 1C current, i.e. the rated discharge charge capacity divided by 1/2 hours. A 0.5C (C/2) rate would correspond to a current magnitude half that of the 1C current, i.e. the rated discharge charge capacity divided by 1/0.5 (=2) hours." Of course we're not running at the full c-rate, my idea was just that a high c-rate meant a battery that was eager to deliver power on demand.

My friend is kind of a beta tester for these batteries, I think they even have a 1000mAh 3.2V unit for less than $2, so I could string together 10 of them for 32V. The 1000mAh should then last about 3 hours. Have I got the math right this time? How much does the amp draw? How would by battery driven plans affect the other typical board mods, some would be un-needed with battery power?

Last edited by temp123456; 8th April 2010 at 02:10 AM.
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Old 8th April 2010, 02:52 AM   #1278
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Originally Posted by wwenze View Post
Talking about cooling for the 4-channel board, when trying to cool multiple components with a single big heatsink thermal pads between each component and the heatsink are recommended to avoid bad contact.
That makes sense to me. I think what happens is its hard for Sure, on a $50 board, to get all 4 amp IC's on the same exact horizontal plane and same height. Sure tries to solve this with big globs of thermal paste. But thermal paste is not all that efficient in thick layers. See 80 Thermal Pastes Tested I would try 4 separate "northbridge" heat sinks originally for PC motherboard.
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Old 8th April 2010, 10:01 AM   #1279
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@temp123456
I've tried LiFePO4 batteries - non-doped, less capacitance and C rating than the ones you're looking at. I was running a 2.6Ah 12.8V pack into an Amp11 ... and it was quite simply excellent. Looooong running time, fautless sound. I was using batteryspace.com LiFePO4's.

Here's a mildly rambling writeup I did on 41hz.com: LiFePO₄ batteries
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Old 8th April 2010, 10:56 AM   #1280
sendler is offline sendler  United States
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Originally Posted by kristleifur View Post
@temp123456
I've tried LiFePO4 batteries - non-doped, less capacitance and C rating than the ones you're looking at. I was running a 2.6Ah 12.8V pack into an Amp11 ... and it was quite simply excellent. Looooong running time, fautless sound. I was using batteryspace.com LiFePO4's.

Here's a mildly rambling writeup I did on 41hz.com: LiFePO₄ batteries
How do you charge them?
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