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nishant's β24+α10 integrated amp build log

beta24

Re: nishant's β24+α10 integrated amp build log

Postby amb » March 3rd, 2013, 10:15 pm

tommarra wrote:...
2. Hammering (okay it was hard tapping) to fit the flat cable on IDC female connector is not a good idea. Plastic breaks!

There are special tools for this, but you can use a vice.

Question 1: About the transformer for B24 - if I build a separate power supply, do I still need a shielded encapsulated trafo from Richard Sumr or could I use a regular toroidal transformer - like this
http://www.mouser.com/ProductDetail/Tri ... 2b3PVWk%3d
This would be about $60 cheaper from Richard.
What are the disadvantages of not using a shielded encapsulated transformer if the power supply is a separate box?

The disadvantage is that the unshielded transformer will emit stronger magnetic fields than the shielded one. If you put the two chassis next to each other, using a shielded transformer will stand a better chance of not causing hum. Since we're dealing with potentially high currents through the umbilical wiring, the two should be fairly close to each other to minimize wire length (to prevent wire resistance and inductance from affecting performance).

Question 2: ...
I was looking at Par-metal - they sell extruded heatsinks - anyone know if they have ones like like HiFi - Pesante type large heatsinks?

Be aware that Par-Metal has recently experienced a fire that destroyed their facilities. It would probably take some time for them to rebuild and get back into business.
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Re: nishant's β24+α10 integrated amp build log

Postby oneplustwo » March 3rd, 2013, 10:28 pm

tommarra wrote:Day 4:

I was looking at Par-metal - they sell extruded heatsinks - anyone know if they have ones like like HiFi - Pesante type large heatsinks?



I've used their heat sinks on a few projects. They'll cut to your length on a few profiles and the good thing is that they'll also anodize which heatsinkusa will not. I think they're prices are good too. Only issue is whether they're available in the short term with the fire as Ti mentioned.
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Re: nishant's β24+α10 integrated amp build log

Postby tommarra » March 4th, 2013, 8:47 am

@amb: got it - will get a shielded trafo. Now wondering if I should also get a shielded trafo for the Alpha 10 power supplies also (s22 and s25)?

It's a pity that par-metal are down they really are a good business hope they get back on their feet soon.

I probably missed it - but what are the dimensions of B24 boards? Will it fit on a six inch heatsink?

I can get black anodized sinks from rapidled.com but they are only six inch wide.
AMB Projects built: B22 (Active ground), S22, S25, LCDunio, D1, D2, A20
AMB Projects in progress: A10+B24 integrated amplifier
http://www.amb.org/forum/nishants-beta24-alpha10-integrated-amp-build-log-t2193.html
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Re: nishant's β24+α10 integrated amp build log

Postby amb » March 4th, 2013, 9:55 am

You can get away with non-shielded transformers for the α10 because they are much smaller and emit much less magnetic field, and you have them also in a separate enclosure.

The β24 PCB is 4.5" x 7.0". But due to the way the MOSFETs are to be mounted you need extra space along both of those edges. It would fit on a 6" tall heatsink (with fins oriented vertically), but it's a tight squeeze.
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Re: nishant's β24+α10 integrated amp build log

Postby dsolodov » March 4th, 2013, 5:28 pm

tomorra wrote:About the transformer for B24 - if I build a separate power supply, do I still need a shielded encapsulated trafo from Richard Sumr or could I use a regular toroidal transformer - like this

http://www.mouser.com/ProductDetail/Tri ... 2b3PVWk%3d

This would be about $60 cheaper from Richard.

What's the thinking about the separate power supply? Is it to build a dual-mono or work around case size limitations?

Par-Panel case with internally mounted heatsinks for b24 & q22 boards makes a reasonably priced option compared to Pleasante Dissipante, but leads to two case setup, and then why not to go dual-mono? The approach also has lower component density, higher capacity caps & larger traffo.

SumR allows to order a transformer with custom windings, which allows for a single traffo, and that saves space. The build manual specs 250VA+ for unregulated PSU, so larger rating can be ordered as well.

What caps have you settled on? I got curious after reading http://www.tnt-audio.com/clinica/ssps2_e.html
Completed AMB projects: M³, σ11, σ25, ε24, γ1, γ2, LCDuino
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Re: nishant's β24+α10 integrated amp build log

Postby tommarra » March 4th, 2013, 9:40 pm

dsolodov wrote:What's the thinking about the separate power supply? Is it to build a dual-mono or work around case size limitations?


For me the primary driver is EMI - when I built a single chasis B22 I faced a lot of issues with EMI even with Sumr' encapsulated transformer and had to redo the enclosure to 2 box. Given the complxity and costs involved in this project I dont want to be in a similar situation.

Also i kind of like the idea of a separate box for power supply - saw a high end system at a colleagues place (think it was top of the line Krell) and it had a separate box for power supply :-)

dsolodov wrote:Par-Panel case with internally mounted heatsinks for b24 & q22 boards makes a reasonably priced option compared to Pleasante Dissipante, but leads to two case setup, and then why not to go dual-mono? The approach also has lower component density, higher capacity caps & larger traffo.


I thought that if I have 2 Sigma 22 tracking regulators, B22 is pretty close to a dual mono amplifier since there are two separate rectifiers feeding each board. Am I right or missing something important?


dsolodov wrote:SumR allows to order a transformer with custom windings, which allows for a single traffo, and that saves space. The build manual specs 250VA+ for unregulated PSU, so larger rating can be ordered as well.



That is the plan - I am going to contact Richard for a large transformer that can supply both the B24 bords as well as the two tracking regulators.

dsolodov wrote:What caps have you settled on? I got curious after reading http://www.tnt-audio.com/clinica/ssps2_e.html


I was hoping to follow amb's refernce build pretty closely in terms of the components. But I am open to suggestions - would you have any recommendations? Or something thats available of Digikey or Mouser. Something like this:
Cornell Dubilier Electronics (CDE) 500C103T050AC2B
http://www.digikey.com/product-detail/e ... -ND/953308

Does ESR really matter in a power supply capacitor?


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AMB Projects built: B22 (Active ground), S22, S25, LCDunio, D1, D2, A20
AMB Projects in progress: A10+B24 integrated amplifier
http://www.amb.org/forum/nishants-beta24-alpha10-integrated-amp-build-log-t2193.html
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Re: nishant's β24+α10 integrated amp build log

Postby amb » March 4th, 2013, 10:59 pm

The concept of a power amp monoblock is to allow the power amps to be situated near the speakers, one on each side, so that the speaker cables can be kept short to avoid reducing the damping factor. It should be used with a preamp with low output impedance in order to drive the long interconnect cables to the power amps. The monoblock configuration also means that the two channels are completely and physically separate entities, which to some people are desirable.

If you like the monoblock concept, and want separate cases for the power supply and the amp sections, then you can do so with four cases -- two on each side. ;)

As far as I know there are no integrated amp monoblocks, because it's more convenient to have one component to connect your sources to, one control to select between those sources, and one knob to change the volume for both channels.

ESR is an important parameter in a power supply capacitor. But you need not get too obsessed with it. The β24 has eight 2200uF caps right on the board across the rails so it already has a good local current storage bank. The external caps are then primarily rectifier filter caps that also serve as supplemental current storage.
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Re: nishant's β24+α10 integrated amp build log

Postby tommarra » March 5th, 2013, 9:29 am

amb wrote:ESR is an important parameter in a power supply capacitor. But you need not get too obsessed with it. The β24 has eight 2200uF caps right on the board across the rails so it already has a good local current storage bank. The external caps are then primarily rectifier filter caps that also serve as supplemental current storage.


So I guess the question is for my B24 build should I just use these:
Nichion LGU1J103MELC http://www.mouser.com/Search/ProductDet ... YskQ%3d%3d for $7.86 per piece vs. these:
EPCOS B41458B8109M http://www.mouser.com/Search/ProductDet ... mRBA%3d%3d for $21.47 per piece? or even some more fancy ones at 30-40 dollars a piece?

What is the benefits of using the higher priced cap?
AMB Projects built: B22 (Active ground), S22, S25, LCDunio, D1, D2, A20
AMB Projects in progress: A10+B24 integrated amplifier
http://www.amb.org/forum/nishants-beta24-alpha10-integrated-amp-build-log-t2193.html
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Re: nishant's β24+α10 integrated amp build log

Postby amb » March 5th, 2013, 1:24 pm

You need to consider the appropriate mounting style to fit your needs. Screw-terminal type capacitors tend to be more expensive.
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Re: nishant's β24+α10 integrated amp build log

Postby tommarra » March 5th, 2013, 4:32 pm

A number of you have messaged me asking for the BoM for B24 and A10.

Attached excel sheet and the links to Mouser projects cover all the parts I needed (except for the transformers, boxes, hook wires etc.)


Hopefully this is helpful.

1. B24 Main power supply:
http://www.mouser.com/ProjectManager/Pr ... 8f91312b10

2. E24:
http://www.mouser.com/ProjectManager/Pr ... 3ed3dd6a42

3. B24 boards and backpanel parts
http://www.mouser.com/ProjectManager/Pr ... 28d812740e

4. S22 for B24 tracking supply (36V)
http://www.mouser.com/ProjectManager/Pr ... ed1b19df55


Building the A10 sans the backplane requires me to build S25, D1, D2, LCDunio, S22 and A20. Here are the mouser projects for these projects.

5. S25 - 5V:
http://www.mouser.com/ProjectManager/Pr ... 715db00b4a

6. LCD Unio:
http://www.mouser.com/ProjectManager/Pr ... 1c8470ce02

7. A20
http://www.mouser.com/ProjectManager/Pr ... 449849ec05

8. D1
http://www.mouser.com/ProjectManager/Pr ... e5a2a5d82a

9. D2
http://www.mouser.com/ProjectManager/Pr ... 7f6885b252

10. S22 15 V

http://www.mouser.com/ProjectManager/Pr ... 36c28f8e89

B24+A10.zip


In the spreadsheet that were ordered via Mouser have been marked in one of the columnn. Parts from AMB shop have been marked separately. Basically most transistors, matched quads and diodes have been supplied by Ti.
You do not have the required permissions to view the files attached to this post.
AMB Projects built: B22 (Active ground), S22, S25, LCDunio, D1, D2, A20
AMB Projects in progress: A10+B24 integrated amplifier
http://www.amb.org/forum/nishants-beta24-alpha10-integrated-amp-build-log-t2193.html
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