Almi's Logitech Z-5500 Mod (High-End upgrade for the speaker system)

[ramachandra]

The same thing, you just need one more cable, and find a way to connect bot to the sound card. I suggest to use 3 jack adapters like this:

 

[jayjayuk]

ok... just checking back in with the story thus far... i have been playing around with op-amplifiers making them operate in different ways and generally getting to know them. i had the idea that if i use a board i have (the original blown board that i fixed) i was going to try and cut pins 2 & 3 on the tda amp to invert the signal... this is easier said then done as there is not much space and possibility of short... plus the tda may of need to be setup differently for an inverted signal... so that idea stopped when i thought to use op-amps to invert the signal first... they then go to the non inverted tda amp and the end result is still an inverted signal.... so i have had to use little PCB adapters (soic20 to dip20) as the boards to put the op-amps on and the components... the design is like the original op-amps but is now inverted.
 
The first test i did was on my test board... i used both the rear channels for the test... left one as standard and used an op-amp to invert the signal of the other rear channel... i then put a speaker on the left channel (red+black) and the right channel (red+black) to make sure they sounded the same which they did... i then put the speaker on the red terminal of the rear left and the red terminal of the rear right... straight away i could tell the sound volume increased straight away and it sounded alot clearer and detailed sound... i like this mod alot. i have also kept the 0.47uF capacitors in the original post (third mod) which is after the op-amp and goes to the input of the tda amp. this setup is just like the original but like i say inverted. i still have more work to do as i have only done the rear channels and the front... i need to wait for more boards to finish the center channel... i will then (have someone else) cut a hole in the side (or top) of the sub so the plate amp can go on... then i will mount the transformer and do all the necessary wiring to tie both amps together... at that point i will have both plate amps... one will be inverted to the other so i can have all 10 outputs separate... or i can use all the red terminals between the two plate amps so they are bridged and have more power. i will also be looking into a bridged & parallel configuration for the sub... so the subs load will be spread across 4 tda amps instead of two... this will keep the heat down a bit more... or i might just put speaker terminals on the back of the plate amp and give another sub output... i could even use a switch to change between the two. another good thing about bridging these amps is will get double the slew rate from the tda amps when they are bridged.
 
here is a couple pictures so far... it does not look great (like most of my mods on this system lol) but i am aiming for the functionality rather than visual appearance (good job really lol) i got the board epoxied onto the other board last night and soldered all the wires into place then did alot more epoxying as i needed to secure the wires... will be good when it is done... i also bought another working sub/amp from ebay for £15 (+£15 P&P) so i will have one sub with two plate amps on to bridge them to drive more load... and also i will tie the second sub/amp in parallel with the control pod..... anyway... here is the pics.....
 


 
 
i have not tested this yet as it has been on the main board like this... but i did test each op-amp right before i did this and all outputs was fine and had no noise when the volume was turned down so thats a good sign so far... i am going to wire it into the other sub/amp temporarily just to see how things go... the main thing is getting the sub box cut... i dont want to cut it because i am not good with wood and i want it to be rite first time... i will report back in when i have done some more mods/testing ... things are progressing very well with this at the min... after i have done this i will eventually change the main filter caps and stuff like that... just this mod has had me intrigued for a while now and it is finally coming together
 
Cheers

 

[A-Force]

HEY guys PROBLEM Only the stereo op amp (the 3 pins as you can see)...the other op amps + caps are working perfect!!! And by the way after the mod the sound is....AMAAAAZIIIINNNGGGGGG!!!! I cant believe my ears!!!! I m looking forward to start the woofer mod now to improve it even more!!!! This was my first time to do this stuff so i make a mistake (hopefully the last). So what s the solution to this situation? if i fill the holes with solder is it going to work? And something else...if i do the 3rd mod can i bypass the control pod or the 3rd mod works only with the control pod?

 

[ramachandra]

Check the other thread "Fix for damaged PCB". The third mod working with or without the pod.

 

[sanscorp]

Hi all,
 
Quick intro: I'm Sander, 28, from the Netherlands.
I'm not an audio enthousiast and the mods on the first page go way beyond my scope, but I do like some bass and the Z5500 packs quite a punch.
I also do like a free sub and upgrade, p.s. I allready owned a Z5500 set but that's currently occupied by my girlfriend who studies and spends more time behind the pc then I do.
 
I'm sorry to bring this old topic up again.
I have a headless Z5500 sub, I got it from the dump for free, changed out the fuse and created a simple cable to be able to play audio with a 2.1 setup.
 
I have a 100k lin stereo pot but I'm waiting on my order to arrive: stereo 10k log pot.
The sub is controlled by a 22k mono lin pot.
 
I'd like to control the master volume but can't find the "6 channel potentiometer" mentioned in post 59 on page 4 (bottom).
Is there a simple and most of all cheap way to control the main volume?
And if so, is there a schematic available how to wire it up?
I do have plenty of electronic shops arround, but none of them are "specialized" in audio components.
I'm also not willing to spend a 100 bucks on wire wound pots or whatever Looking for a cheap fix (10 euro, 15 dollar range)
 
thank you in advance!
 
Sander.

 

[A-Force]

hey guys is it possible to the op amp to be half broken? i mean from the front channel of the audio card i hear only right channel and the left channel is dirty and lower volume. is it posile that the op amp is faulty or i make mistake to the bridge of the broken pads?

 

[ramachandra]

Hi Sander, this is all i found on eBay at the moment:
http://www.ebay.ie/itm/6-Way-Pot-Six-Gang-Potentiometer-Linear-and-Log-Types-Splined-Shaft-Various-/120789129838?pt=UK_BOI_Electrical_Components_Supplies_ET&var=&hash=item1c1f97da6e
 
I had seen 6 channel ALPS volume control with remote control in the past like this. Try to contact the seller maybe he know something:
http://www.ebay.ie/itm/2-channel-Remote-Motor-ALPS-Volume-Potentiometer-Control-Adjust-50KA-12V-led-/400777575280?pt=US_Amplifier_Parts_Components&hash=item5d50347b70
 
Now the only problem is you still able to control 5 channels and the Sub need a separated pot, because the volume will be not in balance with the rest. At least that is happened with the 50K pot i used, 20K maybe better still i doubt it will work out as expected for 6 channels together.
 
 
 
A-Force I suspect a contact problem, use the diode tester function on a multimeter to be sure the bridge is working and the pins connected to the next component. If they are connected still no luck use a new OpAmp.

 

[A-Force]

Thank you for the answer!!! I don' t know which tcxo to choose...can you help??
http://www.ebay.com/itm/1pcs-Vanguard-TCXO-0-1ppm-24-576MHz-Ultra-precision-Golden-Oscillator-AQ-/121321461708?pt=US_Amplifier_Parts_Components&hash=item1c3f5297cc
http://www.ebay.com/itm/1-pcs-TCXO-0-1ppm-24-576MHz-Ultra-precision-Golden-Oscillator-for-DAC-audio-DIY-/141408940110?pt=US_Amplifier_Parts_Components&hash=item20eca1304e
http://www.ebay.com/itm/Low-jitter-TCXO-24-576MHz-Phase-Noise-135dBc-1KHz-Tentlabs-compatible-/301229184989?pt=US_CD_Players_Recorders&hash=item4622a897dd
or should i choose something cheap like http://www.ebay.com/itm/ONE-PIECE-PRECISION-0-3ppm-24-576MHz-DIP-TCXO-/141421463859?pt=LH_DefaultDomain_0&hash=item20ed604933
I don t know what s more important...phase noise or ppm.

 

[ramachandra]

I suggest the the second link. The first is more expensive, the 3. is only 1ppm and 4. is not reveal enough info about the precision and can be above 24ppm

 

[A-Force]

whats the phase noise of the jyec tcxo? i thimk that is worse than the -125db of the vanguard that's why they didn t write it. what do you think.

 

[ramachandra]

The phase noise is the imperfection of the generated signal (jitter). I do not find the datasheet, the seller maybe know something.

 

[A-Force]

he knew you were right he sent me pdf!!! anyway... between the tda chips and the heat sink there is a white paste and some plastic... whats the real use of these plastic pieces? is it necessary in order to work?

 

[ramachandra]

The small sheets called mica insulators, the white stuff is thermal paste to fill the gaps. The Mica is a mineral, not related to plastics. The purpose is to insulate the TDA Amps and voltage regulator from the ground and each other, and let the heat pass to the sinks. Misplacing or leaving them out is a smoky mistake.

 

[Kuro-Neko]

  So, no feedback about crossover frequency?
I hope someone will comment about it, I would really like some opinions.

 
I am too searching for a way to get around this problem. I really like the pod so getting rid of it isnt an option.
 
I have been studying the chips too and from what I can tell the most logical place to start is the NJW1150. According to the datasheet the chips tone control could be bypassed by simply making a bridge before the tone control input on the chip to the output side, and you will get to keep the volume control ability. However I am not confident enough in my soldering to try this yet due to the need of desoldering smd components so if anyone could test this theory it would be great!
 
The NJW1150 has two tone control inputs and outputs, one for left channel and one for right. This is great because one can test the difference between the right and left speaker!
 
The datasheet can be found here: http://pdf.datasheetcatalog.com/datasheet/newjapanradio/de05058.pdf
 
Looking at page 2 you can see the RTIN and RTOUT (pin 4-5) that need to be bridged. This should disable tone control for the right channel.
 
Also there is a very suspicious feature on this chip (look at page 9) that suggests that one could change cut-off frequency by replacing 2 (right/left channel) smd caps, what kind of cut-off this is i dont know but it is certainly interesting!
 
"There has to be a way!" Right?

 

[Kuro-Neko]

I successfully removed the two smd components and bridged the input and output on one channel using the old resistor, and after fading between the channels and trying different inputs and settings i came to the conclusion that there was no difference AT ALL!!
 
It's as if i never changed anything in the first place, which is very odd! I expected at least a difference in volume but there is nothing, I'm not even sure if I should try and solder the components back as i can't tell any difference between the channels.
 
It's still sending all the low frequencies going to the fronts, center and back (using 6 ch direct) straight to the sub. Almost as if theres a frequency splitter rather than a crossover. I also discovered that when lowering the volume for either R or L front the sub is fading a bit, this kind of makes me believe that the frequency cut is not in a chip but somewhere on the signal path on the board for each channel. Just a theory though.
 
This unfortunately rules out the NJW1150 as the culprit, unless it does it in the volume part (which i think is highly unlikely) the crossover is somewhere else. Any ideas?