Wanted: Crown K2 service manual or schematics

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len_scanlan

Member
Joined 2004
Maxxarcade said:


The amp will draw over 150 watts at idle and decrease the life of components due to heat. Of course if you're using these at home, where continuous use will not happen, this may be ok.

Also, for anyone replacing the output FETs with Fairchild FQP16N25C parts, there are some components that need changing on the main board if you have an older amp. Let me know if you need it and I will send.
Click to expand...

Hi Maxxarcade,

Thanks for all your advice so far - I did consider the effect of heat ageing electros on the board over time. So I'll be replacing ALL small electros on my units as a precaution. Only a few dollars for peace of mind.

Can you give any further details about changes on the main board when using the Fairchild FETs? I checked On-Semi's site and the original Motorola MTP16N25E mosfets are now obsolete. I did find a possible replacement from STM which is available from Digikey: STB16NB25

Increasing the standby delay is certainly of interest as at least one of these will be used for Sub duties at home. I think something like 1 minute delay before power down would be more appropriate in the home.

cheers,

Len.
 
M

mrx23

Member
Joined 2004
HERE IS THE K1/K2 SCHEMATIC!!!!!!!!!!!!!!!!!!!!!!:)
Everybody can download directly.
http://onlany23.atw.hu/k1k2.zip
10MB zip

So we can start rebuild it!!!!
Its way better than ClassD, the FETs have got
separate Drivers with NO deadtime.
(you also have to use 2 coil like in ClassD,
but the only drawback is that you MUST use symetrical supply, you cant use H-bridge with asymetrical.)
Thank to NO dead time the THD will be very low!!!

Its really unbelievable that the whole amplifier's
heart is 2*2 LM361 precision comparator! (you can replacet with with other precision (whis HAS got differential output).

I will rebuild it (in a 100W version) with only using few parts:
4Mhz clock (divided to 250Khz), integrator, 2 precision comps, fet drive+fet,filter,overcurrent protection,temperature protection,and an input buffer, and some SMPS supply (for car).
So it have about 10 ICs (not 200+) :)
Feel free for using the circuit :D:D:D
You can build a powerful Profesional amp!!!
(you can build it BUT you mustn't sell it!!!)

You have to wait about 20minutes, I have to upload it first.
 
M

Maxxarcade

Member
Joined 2005
len_scanlan said:


Hi Maxxarcade,

Thanks for all your advice so far - I did consider the effect of heat ageing electros on the board over time. So I'll be replacing ALL small electros on my units as a precaution. Only a few dollars for peace of mind.

Can you give any further details about changes on the main board when using the Fairchild FETs? I checked On-Semi's site and the original Motorola MTP16N25E mosfets are now obsolete. I did find a possible replacement from STM which is available from Digikey: STB16NB25

Increasing the standby delay is certainly of interest as at least one of these will be used for Sub duties at home. I think something like 1 minute delay before power down would be more appropriate in the home.

cheers,

Len.
Click to expand...


Details are in the zip file that was just uploaded to the site by mrx23. If you can't find it, let me know. There are 3 or 4 componenets on the main board that need changing to use newer FETs. It's called a compensation mod. Use the instructions under using new output modules with older main boards.
 
M

mrx23

Member
Joined 2004
Please explain me how does the feedbacks work in the k2/k1!

So there is an I monitor at the output
the signals from it gos to an error amplifier (that varies the sound input), and goes to the triangle generator.

The second feedback is the "FO" and its goes to the
triangle generator and the DC servo (the dc remover).

But the feedbacks are after the coils so the signals from them are phase shifted?

What does happening when the I monitor recognises
normal currents? How its modifing the sound signal, and the triangle?

There are a lots of R-s and C-s on the feedback line what do they do? Do they correct the shifted phase?

If DC servo circuit sees DC on the output what does it do?

What doese the response EQ circuit do?

The I monitors output is 1V/5A, so the maximum is about 2,5V.

What kind of diode do you recommend?
The service manual only says: 4x300V ultrafast TO-220
nothing else:(

I read the service manual many times but there are some things that not mentioned.

So please help me to understand these feedbacks,
I only need that to redesign the amp :)
 
V

Vek

The idea of designing a smaller version (say "K0") of this amp sounds nice to me also ...

I think it would be a good idea to open a new thread in the class d forum concerning this concept. :nod:

There might be the right people to answer your questions and you may raise some interest in this topic!

Please leave a message if/when you do so, I'm very interested in the findings!

Cheers
 
lumanauw

lumanauw

Ex-Moderator
Joined 2002
facebook.com/valveaudio
The point where input (from preamp) and output (from output node) are compared is at junction of R100 (4k99) and R106+R105+R104. It makes an inverting amplifier byU100D(33079). The gain factor is determined here.
From U100D, the signal is splitted to normal (R124) and invert (R110). Then they are modulated by triangle at U101 and U103.
T100 is for detecting current, maybe it is also used for overcurrent protection.

Why is the input has tobe filtered by 7th order gaussian filter, also the output has to be filtered so much order?
 
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