125asx2 in btl ?

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bubuchef

Member
Joined 2009
#1
Hi everybody,


i bought a icepower 125asx2 from a friend .

i plan to use it in btl with asymetrical ( mono cinch) input.
i ordered a cable set from ghent, china.
but now , i am not shure how to connect the right input to get the correct btl

output !
can anybody help me, my wife fears the house is burning down, in case of wrong connection !😱


thank you for your help !
jochen ( germany )
 
#3
I'm too considering building a stereo amp or monoblocks using a pair of 125ASX2 units in BTL mode, and I could use some advice from someone with some electronics expertise, (which I definitely lack).

The 125ASX2 date sheet illustrates the correct wiring for BTL but I'm confused on a few points -- please refer to the picture from the datasheet, below.
  • Is the little triangle with "-1" implying an external phase inverter device? Or something else" -- I think 'Yes'
  • Does the phrase "pulled low" mean that the BTL Sync connector ought to be connected as shown? -- I think 'Yes'
  • If one had a balance source, (preamp, whatever), would it be correct that the external phase inverter, (as above), would be unnecessary given the the balanced '-' signal is inverted? -- I think 'Yes'
The other problem, of course, is procurement. One fears that the items available from eBay or AliExpress are fake.

An externally hosted image should be here but it was not working when we last tested it.
 
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#4
You are correct on all counts. One of the inputs must be 280 degrees out of phase with the other to achieve BTL and a preamp with a balanced signal output output will do that perfectly. It will Elwood without pulling the TL line low but as far as I know, that line synchronises the oscillators. If you do not do that there will be a small offset between the two carriers and as the offset is quite small, there is a chance that it will occur outside the filter bandwidth and pass through to the speakers.
 
#6
Ideally class D amps in the same box should be synchronized, to prevent switching beat notes getting in anywhere (even if the amps are separate). This might also mean there's only one place to set the frequency for AM interference defeating, for some chips.
If this can't be arranged and different amps share a power supply, filtering the power supply leads for switching frequencies may need some attention.
 
#7
Mark Tillotson said:
Ideally class D amps in the same box should be synchronized, to prevent switching beat notes getting in anywhere (even if the amps are separate). This might also mean there's only one place to set the frequency for AM interference defeating, for some chips.
If this can't be arranged and different amps share a power supply, filtering the power supply leads for switching frequencies may need some attention.
Click to expand...
That sync. is exactly what the BTL-sync pin does for the two channels on a board. Sync between the two BTL boards should not be necesasry and in any case the ICEpower amps have load-dependent switching frequencies.

@feanor: Remember that "pulled low" here means connected to the power supply ground, either the mid-point of the AUX-supply or the mounting pad directly next to the connector.

Also, I've said this before but I have yet to see (even) a picture of a fake 50ASX/125ASX module despite many claims that they may be out there. I wouldn't be too concerned to be honest. The "fakes" I have seen of the A-series were so easy to spot that I hope noone would ever mistake them for the originals.
 
#8
Nisbeth said:
That sync. is exactly what the BTL-sync pin does for the two channels on a board. Sync between the two BTL boards should not be necesasry and in any case the ICEpower amps have load-dependent switching frequencies.

@feanor: Remember that "pulled low" here means connected to the power supply ground, either the mid-point of the AUX-supply or the mounting pad directly next to the connector.

Also, I've said this before but I have yet to see (even) a picture of a fake 50ASX/125ASX module despite many claims that they may be out there. I wouldn't be too concerned to be honest. The "fakes" I have seen of the A-series were so easy to spot that I hope noone would ever mistake them for the originals.
Click to expand...

Thanks to you and the other responders. I'm glad to understand the BTL Sync aspect better.

I'm also glad to be reassured that the eBay and AliExpress are (very likely) genuine. While Chinese fakers are perfectly capably of copying complex circuits if theY set their minds to it, the economic payback would be dubious in cases like this IMHO.
 
#11
hi,
please excuse bad english !
if you want to connect your single source preamp to the 125asx in btl, you need this device :
NE5532 Unbalanced to Balance Converter Board ​
Match Differential Input Amplifier​

Description:

Using original NE5532 chip designed unbalanced to balance board, single power supply input, can match the differential input (balanced input) of the power amplifier board, can also be used as a two-channel amplifier board to change BTL output. AC or DC power supply dual-use, DC input does not need to distinguish between positive and negative polarity.

Operating Voltage: AC 6-16V or DC 8-24V

Board Size: 50mm * 33mm

Board Height: about 22mm

Channel: Mono

i bought it from ebay for appr. 5 $
the single input signal will be changed into two signals, one of them is turned
to 180° .
so you have a symmetric signal, in doing so, you can connect both signals to the icepower inputs.
the supply voltage can be taken from "aux" of the board.
please read the advices written above, what to do with the ground pin !
i hope, i could explain to you, what is necessary to get full power in btl mode !
greetings from germany
 
#13
no i could`t finish my projekt because of a serious mistake i made :
some tin-solder drops fell from my soldering iron on the board, while it was powered up !
thunder and lightnin' !!

my dog Eddie jumped under the bed, my wife cried and i threw the burning icepower-board in the garbage can !
few days later, i bought from connexelectronic (china) a IRS500smps.
it was about 120 $, delivers 550 W into 4 ohm and i can use symm. or unsymm. !
very happy with it !
good luck with your project !
bubuchef
IRS500SMPS.jpg
 
#14
no i could`t finish my projekt because of a serious mistake i made :
some tin-solder drops fell from my soldering iron on the board, while it was powered up !
thunder and lightnin' !!

my dog Eddie jumped under the bed, my wife cried and i threw the burning icepower-board in the garbage can !
few days later, i bought from connexelectronic (china) a IRS500smps.
it was about 120 $, delivers 550 W into 4 ohm and i can use symm. or unsymm. !
very happy with it !
good luck with your project !
bubuchef
IRS500SMPS.jpg
 
#15
bubuchef said:
no i could`t finish my projekt because of a serious mistake i made :
some tin-solder drops fell from my soldering iron on the board, while it was powered up !
thunder and lightnin' !!

my dog Eddie jumped under the bed, my wife cried and i threw the burning icepower-board in the garbage can !
few days later, i bought from connexelectronic (china) a IRS500smps.
it was about 120 $, delivers 550 W into 4 ohm and i can use symm. or unsymm. !
very happy with it !
good luck with your project !
bubuchef
Click to expand...
Which model did you buy, the one with a heatsink or with a heat slug? What are you impressions of the quality?
 
#16
i chose the one as shown above, put it in a case, added volumne control and a small heatsink.
i am very satisfied with it, no hum no noise, very stable !
i use it together with a small Behringer tube preamp to power up my set.( bassplayer in a rockband)

i bought several different modules fro Connexelectronic, allways recommendable !
sorry, no pictures of my works available !
greetings
bubuchef
 
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