Help for beginner with L25D amp

[Lumi71]

hi there,

i am new to this forum.
at the moment i am looking for a four channel or two stereo amp to power my active speakers.



so i came across the L15-L25D boards. Since i am an absolute beginner in this area i asked along (ebay shop) if he could also finish/assemble the whole amp. and he would do.
He made me an offer with following parts:

power supply:

http://cgi.ebay.com/ws/eBayISAPI.dll...e=STRK:MESE:IT

trafo-
http://cgi.ebay.com/ws/eBayISAPI.dll...e=STRK:MESE:IT

boards-

http://www.ebay.com/itm/Assembled-L2...item19ce8749dc


before deciding to buy i just want to make sure if these parts are a good combination.- as i really have no idea...

also important is that the amp should be capable of driving at least 3 ohm (imp. min. of the woofer) .


thanks a lot
stefan

 

[Lumi71]

no one to help..?

 

[jogas]

Hello
As I understood from the specs on ebay

- the trafo gives 40-0-40 Vac that means 56-0-56 VDC on the caps.
- the caps on the PS board are rated 50VDC (too low)

The L25D needs min 60VDC recommended 70VDC max 80 VDC, therefore you risk to blow up the Caps and even if they survive you have not enough volts to correctly power your L25 amps, moreover, in my opinion a single 300W transfomer is just enough for one amp, (assuming it has the right voltage)

regards
Giuseppe

 

[exflaco]

Hey Jogas the 50v capacitors are near the l2092 in the zone 5,6v and 12v zeners before the 3k3 resistence 50v are aceptable,sorry my poor english work very well the sound es good as especifications

 

[exflaco]

Lumi 71 your choice l15d works fine 4ohm ,wats woofer you are? 3 ohm very rare

 

[Lumi71]

thanks, so far guys!

the woofer are nominated for 4 ohms, but the impedance minimum is 3 ohm....
the amp boards would be the l25d, not the l15d

 

[exflaco]

Lumi the l25d Dont work 4ohm i have 6 ld25 and 2 ld15 ,only ld15 work 4ohms l25d cut at 4 the oscilator

 

[deChrLam]

Hi Lumi,

The 50 Volt Caps on the power supply are too low voltage. The might explode on you.
The 40 Volt transformer will give after rectification 40 X 1.4 = 56 Volts DC which the capacitors have to handle. 56 Volts is a bit too little for the L25D. The designer recommended to me a 45 Volt transformer and a power supply with 80 Volt capacitors. Stick with the L25D, one guy reported some problems with his 2.5 Ohm minimum speakers with the L15D.

Where are you located?

 

[Lumi71]

i am in germany

 

[jogas]

@EXFLACO

I was talking about the Power supply board to be ordered by Lumi.
The board is showing 50VDc caps.
If you feed the board with 40Vac -> 56VDC you may blow the caps, therefore that board is not usable with 40Vac tarnsformer and moreover, the recommended values for the L25 are 60-70-80 VDC.
regards
Giuseppe

 

[exflaco]

Sorry i dont undestand,off course the power supply is logic 100v capacitors

 

[Lumi71]

thanks guys!
so i assume this kit would not be a good option to choose.

so would you have a power supply/Transformer in mind that would match?
could also be a complete switch mode board ....

think there was some that used a HypexSMPS400A
http://www.hypex.nl/docs/SMPS400_datasheet.pdf


to power up two L25D..
what do you think?
or other recommendations?

 

[deChrLam]

Hoi Lumni,

Germany, somehow I had a feeling that you were in Germany.
A few weeks ago I built an amplifier consisting of:

2 x L25D Amplifier boards
2 x 500VA RKT-500 Secondary: 2x45V Toroidal Transformers
AudioCreativ - Ringkerntransformatoren (Becher)
2 x Power supply 60.000uF / 80V
AudioCreativ - Elko - Netzteilplatine mit 60.000uF / 80V
2 x Stereo soft start, protection circuit modules.( I may change upgrade to two L25D per channel - you will need two mono units.
AudioCreativ - High-End Kombimodul: Lautsprecherschutzschaltung + Softstart
The case is from Italy all Alu Black 3mm eloxiert 10mm front plate - the last one on this page
modushop.biz
Audiocreativ have the cases from this company, but not with a 10mm front plate.

The rest of my stuff was from Thel Audio world:
1 x 2CP-2500M /10
1 x CB-400G ROT
1 x CB-400G SCHWARZ
2 x LT-250G
4 x LS-150G
1 x KGSS
1 x AV-66
1 x AA-300
1 x AD-06
1 x MW40/50
2M BLC-100 s

just google thel and the part number.
Wenn du Bilder gucken willst oder mehr erfahren willst, dann bitte PN an mich. Schöne Grüsse aus der Ostschweiz.

Need pics or more info, then PM me.

 

[pietroruta]

l25d amplifier with Power supply +/- 70v of how much current is needed to pull out 250watt of power ??? I don't understand how to size the transformer or smps power supply .... what is the calculation to know the current needed ??? and how to size fuses protection ????