Going to buy a AMP11, preQ's!

[Fizzy]

I'm going to use 2 of these with one PS1 in a case of some sort (the exact one is not decided yet ).

How high is the PS1 unit? How well will it work with 2 AMP11?

What toroid do I need for the normal version of AMP11 (if my calculations correct I need around 22 Vac )? will this do 160 VA , 22 Vac or will I need more power or other Vac (have I got anything right at all:P)?

Heard somewhere about the R-core transformers , are this better then regular or at least take less space?? I want the system to be as small as possible!!

How much cooling do this AMP need (it needs to be cooled on the bottom right?)? Will a aluminium bottom of the case be enough or do i need to add a heat sink??

I have solder some 0603 and a few LEDs in 0402 earlier (just a few devboards for a arm cortex mcu) and a few 100LQFP (if anyone has seen them ) , how small are the components in relation to those , and will I have a chance to complete this board with that beginner skills?

Sorry for all questions and hope to get some nice answears!

/Kristoffer Hansson!

[Fernando]

You can find some data at http://www.41hz.com/forums/showthrea...d-an-AMP/page2

The smd are 0805, too hard, too little for me. I asked help.
Other problem is the termal disspation of the boards with their big ground planes. A good iron (60W or more) is required.

The first thing you must decide is the voltage (and model) of the AMP11. Only after you can choose the transformer and evaluate the power.
I choosed 32V but the transformer is 21V so I get 32.6 with no load. With heavy load maybe 30V.

[Fizzy]

Yea, the Idea was to go with the standard 32v amp11 (that was what my calculation was done with) , SO de recomended for two amp11 is a 300 VA toroid?? wouldnt 160VA (or maybe around 200) be enough??

where did you buy the R-core ?

how mutch cooling does this amps need? Would a decent small alu-case be enough or do i need more?

Yea but the 0805 is a bit bigger then the 0603 atleast and I have a decent iron to borrow at my schools electonics club (maybe around 80w) . So i might handle the size (or atleast get some experience ^^).

Thanks for your answear! Got some of my questions answeard! (and myabe some more questions to ask )

[Fernando]

If you read my thread you find:
"
I have now:
- An autocostruire.com Galaxy case (GX 383)
- A selectronic.fr R-core transformer (300VA, 2x21V)
- A RS IEC (Schaffner FN 284-6/06) with 2 slow 2A fuses
- 41Hz PS1 and AMP11 32V
"
In the BOM you find the TP2050:
FEATURE S
Class-T Architecture
High Output power
35W @ 6Ω, < 1% THD+N
50W @ 8Ω, < 3% THD+N
117W @ 4Ω, < 10.0% THD+N (paralleled outputs)
Audiophile Quality Sound
0.007% THD+N @ 30W 8Ω
0.005% THD+N @ 70W 4Ω (paralleled outputs)
High Efficiency
92% @ 60W 8Ω
85% @ 46W 6Ω
89% @ 117W 4Ω (paralleled outputs)

The datasheet make me think that you could get 80W (4Ω) of good output with 31V. Two x 80=160W. If Efficienty of 85% you need 190W.
And maybe you can use 95% of efficienty for the transformer, if it is good. So 200W is the minimum. If you want a margin you get 240W or more.

But the chip I received was a STA505, not the TP2050. Don't know the difference...

I used 300VA because I didn't find at selectronic a r-core with less. And 120VA is not enough, maybe 2x120VA.

Who can help with this power calculation?

[Fizzy]

hmm maybe Ill go with the LV version then so I dont need that mutch power out (really want an small system and power isnt that important since its going to be a computer audio system).

Is the LV max 24 V or just suitible for that? Is it possible to use it with a 18 Vac (~25.5 V) toroid or do I need to go down to a 15Vac?? And ill guess with this it will be enough to have 160 or better safe then sorry 225 VA.

Do you just screw your boards directly to the case for the cooling? or do you have some other cooling added?

I really appreciate your help! Thanks !

[Fernando]

The power is never too much. You are not obliged to use it all. But if you pay too much for something you don't use at all you must reconsider.
Maybe the LV is easier. One LV difference are the inductors (toroids) that are ready to use. I made mines following the technic I found at the forum (http://www.41hz.com/forums/content.p...idal-Inductors) and they look quite nice. See http://www.41hz.com/forums/content.p...osing-Your-AMP.
After you know the power calculate the eficiency and the termal dissipation. You can use the voltage you want if the capacitors are adequate. I think the capacitors are the big difference between AMP11 LV and the AMP11 32. Ask for different capacitors before you buy if you want to use more than the maximum recomended LV voltage (24V).
If you go with the LV you need a little transformer, a little case, etc. If it is enough you must choose it.
I am bulding my first AMP so I can not give you more useful data for now. But I will write in my thread what I discover and what I do.
The PS1 is screwed to the case with metalic computer motherboard spacers. The two AMP11 will be screwed with an aluminium sheet I will make myself so they become vertically mounted and with space for coolers. I think that 12W coolers are adequate but only after stress tests I will know for sure.

[Fizzy]

Sorry for my late answer.

Thx for the links , so a little aluminium case should be enough for the cooling (or a decent small cooler)? Do you have any link to the cooler you are going to use or is it the case itself? When you have any results please write them here

[V-bro]

Autocostruire cases are just hifi2000 cases, only more expensive... They have an Ecommerce site called http://www.modushop.biz

Unlike almost any other TK2050 amplifier available the 41hz TK2050 amps run quite cool. This is due to good parts choice and a good board design. A small slab of aluminium is more than sufficient to cool this amp at voltages up to 32Vdc. The -HV version needs a little larger heat sink at voltages of up to 52Vdc. This is proof of the extremely good high frequency behaviour in the designs. There are so many bad designs available that can still sound pretty good, but often need a heatsink the size of a truck at voltages where a 41hz TK2050 amp needs no heatsink at all.

[Fizzy]

Thx, v-bro! So a case-bottom that can hold a ps1 2x Amp11 and a toroid should be sufficient to cool them I guess!

Do you have any toroid recommendations for the amp11 (standard and/or LV) ?? Do my earlier calculations fit (if you know anything about this but I guess so)

How to use a pot for adjusting the volume? My guess is to use it as a voltage divider, would that be correct? Or would I use it as a resistor to adjust the amplification of the Amp ??

[V-bro]

A pot should be a simple 20K log voltage divider.

Any toroid will do quality wise. Just take a sufficient VA rating. For two AMP11 I'd take a minimal of 200VA. Taking anything less than 500VA will not need a softstart though... Then take care of choosing the right voltage. 18Vac is already resulting in quite a powerful amplifier. that's 18x1.41 for the DC voltage...