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SVI2004A

SVI2004A

Member
Joined 2004
Hi There,

you can use any of the abovementioned ICs -

STK4191II - 4192II both are pin compatible 4191II's have a lower distortion - the 4192 is in a smaller casing
4191V is in the smaller casing - HiFi grade (lower distortion)

except the different casing from the 4191II all are identical in pinout and power rating (2x50W MIN)
 
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BlackBLOOD

Member
Joined 2004
Datasheets or shematics

Well i`m geting my self a bunch of STk 4191II tommorow.
They are already ordered.

Anione have a good shematics for them?

I`m going to use the sheme from the 4192II data sheet if don`t find another one..
Any proposes?

PS.Sorry for my bad english.I don`t practice it to much..
 
SVI2004A

SVI2004A

Member
Joined 2004
Convert STK 41XX circuit to Technics new class A

i have recently uncovered that the STK41XX series amplifiers can be upgraded to the (virtually) PIN compatible Technics SVI3000 series (SVI300-3004) the SVI ICS being COMPLIMENTARY SYMMETRY with new class A biasing... simply put IC in place of STK *** PINS 6,7 & 8 are NOT Connected for the SVI (remove components that connect to these pins) - the SVI has alot higher current drive (delivers more power at lower rail voltage)

further Questions - Email :)


- Baily :spin:
 
B

BlackBLOOD

Member
Joined 2004
I`ve just build a STK4191II amp.
It sounds good and it`s not overheating.
I`m very proud of it becouse it`s my first amp.


But got a question.

On the datasheet of the amp there is a diagram.
It says that if my supply voltage is + / - 45V and i use a 4Om speaker the output power will be 130W
130W x 2 or 130W x 1?

becose my curent supply voltage is + / - 46,4 V
and i use 4 om Speakers.
can you tell me your opinion on that question?

10x

ps.I`ve attached the data sheet of STK4191V(pin and power compatilble to STK4191II)
 
B

BlackBLOOD

Member
Joined 2004
BDW can someone explain me this one?


rljones said:
It is interesting that you should make this post, as I was about to start a thread on these hybrid op amps.

A few months ago, I made a pcb for the STK4048XI. [As an aside, this device has full complementary outputs; the 'V' versions, as opposed to the 'XI' versions, are quasi-complementary. A smaller module, the STK4044XI, has 4 output devices and 15 pins; the STK4048XI, 6 output devices and 18 pins. You can ignore the last 3 pins on the '48 if you put a '44 into the same circuit, so design for the 18 pin versions and you can go with either unit.]

Anyhow, I had so many problems that I became frustrated and put them away: horrible oscillation that I could not stop despite trying all sorts of things with the grounding, etc. However, after a friend of mine fried one of my amps, I decided to attempt making a couple of STK modules to put into the damaged unit. This weekend, I finally figured out the problems, one of which is hinted at on the application docs by Sanyo, and another which I accidentally discovered and yet seems very important.

The main secret in stopping oscillation is to keep the gain at 40dB. I don't like amps with this much gain as the input sensitivity is around 0.4 V for full power. This kept me from getting rid of the oscillation as I had initially changed the input resistors from 1K/50K to 1K/20K, and never looked back.

Once you get the gain up, to the suggested 40 dB range, almost all oscillation stops. The amp then looks very good on the scope, except for a little bit of something on the sine waves. (BTW, I used all of the parts suggested on the app docs, various 100pF caps, etc to avoid oscillation as Sanyo warns.) This where the application docs stop. What I found was that there was still oscillation, but at VERY low levels, like 1 mW output into 8 ohms. [And I'm now wondering if this low level oscillation is what has given these guys a back name, particularly with respect to longevity. Any amp that oscillates will overheat and eventually burn-out the output devices.]

At these low levels, the oscillation took off again. I tried all sorts of stuff to fix it: bypassing the feedback resistor with small caps like 10 to 200 pF, changing the input blocking caps, but nothing helped--until the other evening. I was looking at th scope ready to go to bed when I started holding a 200 pF cap across the feedback resistor when the oscillation completely disappeared. But I'd made a mistake, it turns out I'd actually put this capacitor from the amp output side of the feedback resistor to pin 3 going to ground.

In other words, by placing a 200 pF cap from the amp output to ground (but at low current level location; I didn't use the output terminals), the remaining oscillation stopped. The amp then looked absolutely perfect and all distortion dropped 10 dB, especially at low levels. The heatsinks were now cold when idling; before they were warm but this was due to overlooked oscillation.

This STK4048XI produces, with a +/-55 V supply that sags to 50V at full output, 140 W into 8 ohms and 220 W into 4 ohms. Freq response is -0.4 dB at 10 Hz to -2 dB at 100 kHz (limits of my equipment). Distortion (THD) is 0.8mW is 0.08% at 1kHz, 0.025% at 1W, 0.007% at 10W. At 20 kHz and 10W it is 0.035% and only 0.1% at 10W at 50 kHz.

As for sound, it initially sounds very good, not as open or airy as my Rowland amp, but very good. The input needs adjustment: my initially listening was done with an input transformer, which I think may be a mistake on this amp (I was still trying to cut that incredible gain...). Once I get it going, and properly set up, I'll compare it to a Tripath 104, a Rowland, and a homebrew Aleph.
Click to expand...


Will it be good if i put a 200pF cap from the amp output to the ground?And do i must to put a polarised cap or normal cap?
 
B

BlackBLOOD

Member
Joined 2004
Well i see that noone is replyng to my posts..

But i will continue to ask you.

What is the diference between STK 4191II and SKT 4191 ??
I think they are pin compatible but are they the same quality?

I have some STK4191 here and if someone says i may just put them on..

10x

PLS give mio some replays..
 
SVI2004A

SVI2004A

Member
Joined 2004
see post 2 on this thread...

tho again for your benefit,

STK4191II - 4192II both are pin compatible 4191II's have a lower distortion - the 4192 is in a smaller casing
4191V is in the smaller casing - HiFi grade (lower distortion)

except the different casing from the 4191II all are identical in pinout and power rating (2x50W MIN)

- Baily :spin:
 
SVI2004A

SVI2004A

Member
Joined 2004
4191!

oh im sorry - my misread-

STK4191 you say?

mmmm theyre old old old ( as far as my experience goes)
i believe the 4191II is the same speccies as the 4191
(it seems the II was added after some slight refinement or slight change)

however i am impressed you managed to acquire such a rare IC
but the main point is in the sound - if you can hear a difference please post it here :)

- i hope this may be of some help

- Baily :spin:
 
P

p2mine

Member
Joined 2004
hy!

i am also building a surrond system with STK chips. I choosed to use STK4141II for satelites and STK4192 for subwoofer.

the subwoofer amp, with STK4192 bridgeds works perfectly. no oscillation, no buzz, worked perfecly from ther first time powered.

I used for reaction 47k/470.
the input voltage divider was with 1k/22k
the other parts were exactly like in the pdf from sanyo.
(at that time I didn't have the resistors required)
because it worked ok, i never change the resistors values.

a few days ago, i've finished my satelites amplifiers with STK4141II
at the first look, they seem to work ok. but when you stay close to the speakers, you may hear a high-frequency oscillation. the heatsink does not get even warm....

for this amplifiers I used 56k/680 for reaction and the input voltage divider was 1k/47k

the schematic was exactly the one that sanyo recomends.
and still, i'm annoyed with that oscillation.

for the STK4191, they are almost the same as STK4192.
the only difference is that one is made for high-end audio. I have choosen to use 4192 because they are cheaper....

probably you don't need to worry to much about that. just start building... :smash: :smash: :smash:
 
metal

metal

Member
Joined 2004
Hello

STK4191II has larger case that the STK4192II, that is because it can with stand higher operation constaints.

I build it once, it was really powerfull, I liked it more than STK4192II, but its also more expensive. I think it is great for metal, heavy metal, and black metal music.

Two weeks ago, I finished STK4191V, it sounded good, but not as powerful as STK4191II. In deed I don't know why, eventhough Iused the same component values.

Untill now I had no oscillation problems, that sounds good enough for me.

Some thing on my mind, STK4191 in general, how many amperes it needs on each power supply rail when the rails voltages are +36 volt and -36 volt.

Kind Day
 
B

BlackBLOOD

Member
Joined 2004
Add a Resistor/Inductance network befor the speackers...
You will kill the High Freq Oscilaton with it...
:)

Nice Choice with STK 4191V Metal.
I`m not shure if it is less powerfull as you say but it is a realy nice one:)

THD les than 0,08%...

PS.PLS give me the schematics of your Bridged stk 4191II..
10x
 
metal

metal

Member
Joined 2004
Hello

Thank you for the nice reply BlackBlood, you are absolutely right about the distortion of STK4191V, its 0.08%.

Concerning the schematics of bridging STK4191II, there was a thread, in deed the first thread in which I participated, you can search for STK4048XI thread, or the threads I participated, I think you will find every thing you want about bridging the STKs, if you can't find it, we will start it again, no problem.

Kind day
 
P

phantom_zero

Member
Joined 2009
STK4191V Power supply transformer

Hi I have just built the amplifier from the schematic given on the datasheet of the STK4191V but I'm not sure if I'm using the right transformer. When I tested it the transformer heated up and melted the plastic coil former (I'm not sure if that's what it's called :p). The IC's heatsink heated up also. The transformer's secondary is rated at 3 Amperes. I saw on the datasheet of another STK IC which uses same recommended MG-200 equivalent transformer that the recommended bridge rectifier is rated at 4 Amperes. Should I use a 4 Ampere transformer too? Is that where the problem is? or are there any other possibilities of what went wrong? I just wanna add that I ommited the 3 microHenry coil which is connected in parallel to the 4.7 ohm resistor which connects to the load and what would be the effect? Noisier output perhaps?
 
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