Yes I did try without the blocking cap in the inverted leg to ground (I only tried this in the single ended amp, not the balanced bridged version).
When no signal was connected (floating input), as I recall there was about 0.5 to 1 V DC offset without the blocking cap. When an input was connected, DC offset was about 30-50 mV. Normally there is an input connected with a signal, so offset wasn't too bad without the cap. With the cap, it was only a few mV.
When running single ended, I initially had a 470 microfarad cap without bypass. It didn't sound too good and bass was poor. When I removed the blocking cap, the low end was vastly better. I later used two 1200 microfarad or two 1800 microfarad caps in series, to create a non-polarized cap, bypassed with a PP cap. This setuup sounds very good and has very little DC offset. In the bridged version, I use this latter setup.
As for inverted mode, I have not run the amp purely inverted. I have run it balanced, with a + signal for the non-inverted input and the - signal for the inverted. This sounds very good.
When no signal was connected (floating input), as I recall there was about 0.5 to 1 V DC offset without the blocking cap. When an input was connected, DC offset was about 30-50 mV. Normally there is an input connected with a signal, so offset wasn't too bad without the cap. With the cap, it was only a few mV.
When running single ended, I initially had a 470 microfarad cap without bypass. It didn't sound too good and bass was poor. When I removed the blocking cap, the low end was vastly better. I later used two 1200 microfarad or two 1800 microfarad caps in series, to create a non-polarized cap, bypassed with a PP cap. This setuup sounds very good and has very little DC offset. In the bridged version, I use this latter setup.
As for inverted mode, I have not run the amp purely inverted. I have run it balanced, with a + signal for the non-inverted input and the - signal for the inverted. This sounds very good.
I have used the STK4050V. It is very rugged and cheap. I have been using it at a bar, with the load down to 3 ohms driving about 200 watts. Got to reduce the rail voltage to insure long life. Don't drive more than 200 watts, and keep them cool with a good sink. I'm using a fan on mine. For some reason the STK diagram has too much gain, so I reduced it to normal amplifier gain, using a standard line voltage level out of a mixer. I would go for the complimentary versions, but might not be as rugged. I was going to make a bridged STK model, but have not done that yet.
Where to buy
I recently e-mailed these guys, and they said they
had the 4050V in stock - around $19 a peice.
http://www.ceitron.com/
-herm
I recently e-mailed these guys, and they said they
had the 4050V in stock - around $19 a peice.
http://www.ceitron.com/
-herm
true, the benefits of cascodes in some circuits is debatable. in this case it does not seem to improve the distortion figure any, altho global feedback probably neutralizes any inherent linearity improvement measurement-wise. i'll think about giving the 4050 a shot... who knows maybe it sounds better than the 4048 w/o the cascode 
i dunno if it is powerful enough for DJ use. you will probably want something with even more power, like 300Wpc or greater. you can get that much power out of the STK chips if you bridge them, but in bridged mode the current requirements from each chip double. i'm not sure what the impedance of DJ speakers is like.
the chip will deliver probably close to 200wpc (probably more like 150wpc) if you have a beefy enough power supply... i would say at least 500VA transformer with 50,000uF supply capacitance per stereo unit minimum. if you are multi-amping your system, using several STK units, you could get enough power, but it may be more convenient to have one big amp.
i'm not sure if there are more powerful chips than the 4050, i haven't seen any.
the chip will deliver probably close to 200wpc (probably more like 150wpc) if you have a beefy enough power supply... i would say at least 500VA transformer with 50,000uF supply capacitance per stereo unit minimum. if you are multi-amping your system, using several STK units, you could get enough power, but it may be more convenient to have one big amp.
i'm not sure if there are more powerful chips than the 4050, i haven't seen any.
As I posted earlier in this thread, balanced bridged 4048XI gave 350 W into 8 ohms (53V RMS) and I ran up to about 400 W into 4 ohms before backing off (I didn't have any spare devices at that time and didn't want to fry any more than I already had). This was using a 500VA power transformer with 30,000 microfarads per rail per monoblock (so 120,000 for the stereo amp). The rails are running at +/-50VDC with load.
The 4050V being quasi-complementary is probably best for woofers. When playing at a bar or as a DJ, it probably won't matter as this isn't exactly high-end audio environment with fixed seating.
Regards. Robert
The 4050V being quasi-complementary is probably best for woofers. When playing at a bar or as a DJ, it probably won't matter as this isn't exactly high-end audio environment with fixed seating.
Regards. Robert
all the powerfull amp's.......
STK0080 80w 46v 0.1% THD MAX
STK0105 100w 50v 0.1% THD MAX
STK0080II 80w 47v 0.01% THD MAX
STK401-330 100W x2 45V 0.08% TDH MAX
STK401-340 120W x2 51V 0.08% TDH MAX
STK4044XI 100W 51V 0.008% THD MAX
STK4046XI 120W 55V 0.008% THD MAX
STK4048XI 150W 60V 0.008% THD MAX
STK4050V 200W 66V 0.08% THD MAX
STK4241V 120W x2 54V 0.08 THD MAX
STK3152III 150W x2 or 300W X1 72V 0.1% THD Max
STK3152III (300W) is stronger then STK4050V (200W)
STK0080 80w 46v 0.1% THD MAX
STK0105 100w 50v 0.1% THD MAX
STK0080II 80w 47v 0.01% THD MAX
STK401-330 100W x2 45V 0.08% TDH MAX
STK401-340 120W x2 51V 0.08% TDH MAX
STK4044XI 100W 51V 0.008% THD MAX
STK4046XI 120W 55V 0.008% THD MAX
STK4048XI 150W 60V 0.008% THD MAX
STK4050V 200W 66V 0.08% THD MAX
STK4241V 120W x2 54V 0.08 THD MAX
STK3152III 150W x2 or 300W X1 72V 0.1% THD Max
STK3152III (300W) is stronger then STK4050V (200W)
DJ, the STK3152III only gets 300W because it has two channels you can bridge. two bridged 4050's will probably give you more power. robert squeezed at least 350W into 8 ohms using two 4048xi bridged together. both the 4048 and 4050 are more powerful chips than the 3152, the 3152 just has 2 channels in one unit.