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β24: A discrete, cascoded, fully-differential power amplifier - Page 9

post #121 of 309
10/7/08 at 1:36pm
Quote:
Originally Posted by rhys h View Post
To all you gents who are building the b24, how much is it costing you to just populate the boards?
I don't mean this to sound the way that it's going to and you probably aren't thinking along these lines anyway but I'll say it anyway with the hope of avoiding someone getting in way over their head. Populating the PCB's for this project is a very bad way to try and estimate the total project cost and complexity. There is so much beyond the PCBs I'd be surprised if populating the boards got you 1/3 of the way there in either case.
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post #122 of 309
10/7/08 at 2:52pm
Quote:
Originally Posted by rhys h View Post
To all you gents who are building the b24, how much is it costing you to just populate the boards?
I've made my BOM already, in case anyone wonders where I pulled these numbers from.

Populating the two ß24 boards will run over $400. This is not including any transformers, power supply parts or case parts.

Including the unregulated supply and one σ22 board, the cost is at least $600 in parts. This figure can inflate very quickly if you go for expensive transformers or opt for two power supplies. Again, this is not counting any parts for the chassis, including heatsinks.

I wouldn't be at all surprised if this project broke 4 figures for many builders.
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post #123 of 309
10/7/08 at 3:08pm
The biggest expense for me is going to be transformers and casework.

My Front Panel Express work alone is going to run close to $400.
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post #124 of 309
10/7/08 at 3:27pm
Quote:
Originally Posted by MoodySteve View Post
I wouldn't be at all surprised if this project broke 4 figures for many builders.
I'd be surprised if it didn't break that threshold by a good margin. I know when I started running estimates when I was thinking of building one I broke $2k without trying very hard. This is not your run of the mill DIY amp build.
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post #125 of 309
10/7/08 at 3:37pm
Do you think this amplifier is completly over the top to power some b&w 686 loudspeakers? $1000 is pushing it just a little bit for me!
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post #126 of 309
10/7/08 at 3:49pm
Quote:
Originally Posted by rhys h View Post
$1000 is pushing it just a little bit for me!
No idea about the overkill question but if at the onset the budget feels tight I'd run away from this build. There's just too many ways to spend a lot of $$ building this project. In commercial terms (a comparison I generally loathe) you could easily expect to pay in the high 4 to low 5 figures for an amp of this caliber.
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post #127 of 309
10/7/08 at 4:01pm
Agreed. This is not the amp to build if you're on a budget.
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post #128 of 309
10/7/08 at 4:02pm
FWIW, I have not built one of Ti's amps yet, but just about half way through a SE Dynahi build with only a few thing left to do, or buy, I would say that it will easily surpass $1100. I have spent more on materials and tools to build a case than all the pcb's and components combined, the power supply not being much cheaper to build than the amp itself.
I agree with Nate, pcb's and components to populate them would not be 1/3 the way there, for me it was not even 1/5.
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post #129 of 309
10/7/08 at 4:09pm
Ok, i think i will pass on this one! Back to the multiple LM3886's for me...
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post #130 of 309
10/7/08 at 4:16pm
...I must add, and without reservation, it is the most enjoyment I have had in a long long time. I am already planning the next build, even bought some parts here and there.
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post #131 of 309
10/24/08 at 10:13am
This is SUPER impressive work! Though in my opinion a balanced B22 is already as good as it gets for a speaker amp regarding my own tastes, I'll build a B24 just to scare the neighbors.
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post #132 of 309
10/28/08 at 12:16am
what is the lowest impedance speaker that the Beta24 can drive?
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post #133 of 309
10/28/08 at 1:16am
Thread Starter 
Quote:
Originally Posted by cotdt View Post
what is the lowest impedance speaker that the Beta24 can drive?
There is no cut-and-dry answer to that. For a certain output voltage level, halving the impedance results in doubling the output current. The output MOSFETs used in the β24 are rated for >30A, but things like how much heatsinking, how efficient the speakers are, how large and the acoustic characteristics of the room, how loud you listen, how complex and reactive the speaker load is, all play into the overall equation. My own home speakers are about 4-6 ohms nominal, but my listening space is small and these speakers present a fairly benign load to the amp.
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post #134 of 309
10/28/08 at 1:39am
Quote:
Originally Posted by amb View Post
There is no cut-and-dry answer to that. For a certain output voltage level, halving the impedance results in doubling the output current. The output MOSFETs used in the β24 are rated for >30A, but things like how much heatsinking, how efficient the speakers are, how large and the acoustic characteristics of the room, how loud you listen, how complex and reactive the speaker load is, all play into the overall equation. My own home speakers are about 4-6 ohms nominal, but my listening space is small and these speakers present a fairly benign load to the amp.
My speakers are 0.05 ohm (I made it myself from flat strips of aluminum), and I couldn't find any amp that could drive them.

But yeah, 30A WOW! Looks like I am going to watercool my Beta24 with a garden hose.
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post #135 of 309
10/28/08 at 5:42am
Thread Starter 
0.05 ohms is essentially a dead-short. Very few, if any, amplifiers are going to be happy with such a load. You need a transformer.
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