View Full Version : Help choose and build an AMP
I ask your help.
I want to build an amp and I was reading about Sure TK2050, hifimediy, Arjen Helder, etc. when I found your site. You have good references (and in Europe) but I didn't find yet much data about your products.
I have soldering experience and some electronic knowledge but I work with computers, not audio.
I liked the Item # 41 (AMP11-LV). I prefer quality and safety to power. I am thinking to buy 2 AMP-11LV, only one SMPS (Meanwell S-350 W 27V DC 13A SMPS switching power supply?) and I need also a volume control because I want this stereo amplifier to work directly with sources (line level input).
1-Can I use that SMPS? Give alternative links and models please.
2-What is the maximum voltage I can supply?
3-Where can I foun more detailed data about AMP-11?
4-Is this the AMP11 model more suited to me?
what kind of data are you looking for?
That SMPS is a good choice and AMP11-LV is too, it's got ready made inductors, so that saves some time and blisters on the fingers. On the other AMP11 models you have to wind the toroidal inductors by hand.
The max voltage on the -LV is 32Vdc. There is also a 36V version, but then with the toroidal inductors. And there is now the -HV which is usable up to 55Vdc, but since you say you don't need max. power this is not necessary.
Data about the speakers (can I use 4 and 8 Ohm? what is the power if I use 30V DC?).
Data about the input/sensitivity (If I give Line level input ~0.7V what is the power I get? or how much i loose in %?)
Data or graphics about frequence, etc.
Data about tests against the other class-D.
The schematic, I think I will get when I buy.
I think that I am going to buy that model. But you can guide me.
Now I don't have good sound at my home. I think that if i like the amp I will get nice speakers later. And maybe a pre. Now I want this like a generic project (for any speakers, without pre).
Thank you for the answer.
I am now in holydays, I will come back soon.
- that smps, 350W, 27Vdc is plenty for 2x 1mp-11-LV, on 4 or 8 ohm
- 0.7V (rms) is higher than line-level, but amp needs about 1.4Vrms for 100% (depending on gain chosen during build)
- so for 0.7Vrms I'd set (input-) gain to about ~2, during build (see AI=Assembly Instruction, under HOME)
- half the voltage = quarter of power = 25%, ballpark
- basic schematic plus some graphs on datasheet (google for 'TK2050' and choose the Tripath sheet)
- TK2050 = set of TC200x plus TP2050
- 41hz amps have better PCB's and parts
- tests against other class-D.......on the internet: search and find
- these amps have very good drive, dynamics etc. your current speakers will sound better!
And DO browse all the articles under HOME, lots of additional info!
ok, thank you for the answer.
I am still reading and learning and now I think different:
1-Try to buy all equipment from 41hz and if not possible from european sources (RS, etc.)
2- buy Amp11 x2 (maybe the 32 model) and the PS1 and make a case and close them (I was thinking before to use an "external" and "generic" SMPS).
Can someone tell me a good transformer to buy, preference from 41hz or european shop, and the adequate model you think better from Amp11 range? And while I solder I will have time to learn and think better about all this.
I like quality, not power.
I would take the AMP11-LV if you feel you don't want to wind toroidal inductors yourself, but they are just two per amp, so that's not too bad. Then the -LV has a polarity protection diode and polyswitch fuse. The latter is nice to have when you operate it on batteries and don't use a fool proof connector to connect the power. The normal AMP11 doesn't have this, which means the supply voltage reaches the chipset without any components in between, this might be a tiny bit better for the sound. But these components can also simply be bypassed on the -LV and you will have both advantages. The -HV model has a bit nicer output stage chip, but this will not sound any better, just be able to supply more current at a higher voltage = more power. And this model has higher voltage capacitors, which are smaller in value because they are the same size.
I would take the -LV or 32V model and get a PS3 along with it if you want to build monoblocks, a PS1 if you want to put them in one box. Then get some R-core transformers from Selectronic in France, they are great quality. I would say a 120VA is sufficient for one AMP11 monoblock, or a 250VA for a stereo in one box. This should get you plenty of quality...
My cart has:
#37 AMP11 kit (Standard 32V) 2
#48 PS1 Power supply kit 1
I found this at http://www.selectronic.fr/upload/produit/pagecatalogue/9-05.pdf :
300 VA coefficient x 1.13
Tension secondaire: 2 x 30 V
Dimensions: 160 x 121 x 68 mm
€ TTC: 77,00
I will put all the boards in one box.
Can you say if this R-Transformer is good for me? Other options?
Can you say if I will get 2x30V DC with this transformer and the PS1?
And for volume control, what do you thik I mus buy?
TRANSFO TORIQ.300VA 2X30V
74,50 € TTC
How do you compare the first r-transformer with this one?
More 10% when resting ... (• La tension à vide est sensiblement égale à la tension nominale +10%).
Well...amp11-32 is for 32Vdc, so 30Vac (which is the '30V' mentioned for the transformer) is definitely too high.
2x24V (AC) seems just on the edge: one glitch somewhere and .....
So, next one down is 2x21Vac in that 300VA range. It's 'The One' then , I suppose.
Or, 2 transformers of 120VA, with paralleled (in-phase!) 21Vac secondaries if you want to keep the 'mono' idea up a bit bit more. But you'll be OK with one big tranny.
R-core seems better Quality than a Toroid type, according to V-bro. I have no experience with them.
But if you want to save a couple of Euro's and the Toroid is more convenient for you, mechanically (1 big bolt or 4x small) or otherwise: the Toroid is OK too.
You could give the R-core a try, it's only 3 Euro's more, looks nice and V-bro gave recommendation (so it should be good).
But NOT the 30Vac version!
You can use a real pre-amp/tone-control for volume-control for the/this power-amp11, but a good quality potmeter, log-type will often suffice. Depends on your setup.
Usually the 50k pot in the shop is OK and simple.
For convenience and more to show-off:
You could use a thingy from eBay: remote control (nice), pga2311 chip (pretty good), LCD display.
(it needs 2x6Vac, but that will be converted to about 2x9vdc, which you can get from the main PS3 output with a neg+pos regulator)
http://shop.41hz.com/shop/item.asp?itemid=688&catid= PLUS http://shop.41hz.com/shop/item.asp?itemid=690&catid=
so many words again.....
Like FFF mentioned 30Vac is too high, with a full wave rectifier you will get 1.41 times the AC voltage as DC voltage.
So for 32Vdc you should get a transformer of 32/1.41=22,69 Then there is a margin necessary for the load regulation of the transformer, the unloaded voltage is always higher and a 22Vac transformer can easily measure 24-26 when not loaded.
Now this is not much of a problem with the AMP11 because the chipset is rated quite much higher and the capacitors surge voltage is also quite much higher, so I think it is safe to say you can choose a 22Vac transformer.
Then it is said that the load regulation on the R-core transformers is better than toroidal, which means the voltage is more stable with varying load. And what are we using them for here?? Music, a highly varying load.
I also like the construction of them quite much, with the very steady mounting flanges that easily lend themselves to place grommets in, so the acoustic contact with the casing is very low. This will make it less likely to produce irritating humming from the case.
There is one big but though... You can't add extra windings very easy. But with the 32V version there is no need for funny 5V solutions, this works fine straight out of the bags...
About the input level I will see later what I need.
Line levels and their nominal voltage levels from (http://en.wikipedia.org/wiki/Line-level):
Use..............................Nominal level.....Nominal level, VRMS....... Peak Amplitude, VPK
ARD, Germany..............+6 dBu..............1.550 (approximate)........2.192 (approximate)
USA professional audio..+4 dBu..............1.228 (approximate)........1.737 (approximate)
Consumer audio...........−10 dBV..............0.316...........................0 .447
About the voltages I realized now that the usual are the RMS voltages, I was thinking at peak voltages. Sorry.
The transformer I need, with 33.46V peak when idle and 29.6V at full power, is:
300 VA coefficient x 1.13 (1.13*21*1.41=33.46V peak)
Tension secondaire: 2 x 21 V
Dimensions: 160 x 121 x 68 mm
€ TTC: 77,00
Thank you all, I will post the pics as soon I begin bulding it.
The 0805 SMDs are really little. I asked a friend help for the soldering...
Now I am trying to understand a few things about AMP-11. Help me.
1-In the AMP11 Rev 1.05 schematics U10, the MCP101 485DI, has RST available at J4-3 (for what?) and doesn't control the power up of the chips. Is the schematics correct?
2-In the AMP11 Rev 1.05 schematics the MUTE of TC2000 (2001) has a jumper symbol near the AGND. Does it really exists? Is the schematics correct?
3-In the AMP11 Rev 1.05 schematics sheet 3/3 there is a U5. I can not find any reference to it.
PS1 is ready to test.
The 2 AMP11 boards are coming soon.
Don't weigh the info in the schematics too heavy because Jan makes his first drafts as schematics and then sometimes doesn't change revisions, often component numbers don't match perfectly and often he draws components like U5 to symbolise an external voltage source which is not really on the board, but just as a reminder for himself of the function. Look upon them as scrap book drawings. 98% on them is correct, but just not the full 100%...
Trust mostly on the BOM and component placements drawing and AI....
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
Changed R11 (220R) in PS1 to MRS16 Resistor A/P,0.4W,1%,330R
Changed C40 and C41 (390pF) in one board to C0G 50V 330pF because I lost the capacitors and didn't find 390pF at RS
Changed R52 and R54 (220k) to Met thin film 0805 0.125W 270kR 0.1%
Choose 12k for R114 and R103 (10k)
The 4 toroids I received seem different: I put all the turns I could and I got one pair with 16.5 and the other with 15.0 uH. Less 2 turns and they was with 15.5 aprox.
Their resistance is 0.115 Ohm aprox.
The PS1 seems OK. The DC voltage I get is 32.6 V with the PS1 alone (picture). I didn't test the AMP11.
The Galaxy case paint is non conductive and to guarantee a good earth I had to remove some paint near the mechanical contacts.
I will come back soon.
The AMP11 are almost finished. I will mount them vertically.
I will check the capacitor polarities again...
This is the original case layout for space avaliation.
With circles you can see the height: The case has 80 (310x230x80), the transformer 70 and the PS1 60 (a little more with the feet).
The dimension are almost correct, I was worried with the heigths...
The heat sink are ref. 11.6985 from selectronic. With 8 ºC/W they dissipate 7.5 W for delta T= 60ºC (if I understood well this heat theory).
The AMP11 boards are ready to mount vertically. One more year and I will finish this project :(.
The rear panel is ready (almost).
For the speakers I can use Neutrik or Vbro connectors. :)
Nice job Fernando!
It's nice to see you taking your time to complete this amp in a professional manner.
These amps really deserve the treatment you are giving them.
Let us know how it sounds when you get this operational.
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