Any comments/changes on this schematic ? - Page 2

dimitri · 15th July 2004, 03:26 PM

Please imagine voltage source between K5 and K6, which will model your preamp. Or your preamp will have infinite output resistance?

Rudy · 15th July 2004, 03:51 PM

sos , i beleave i made a mistake, i mean R5

that pole you or talking about is outside the amp ?

/edit, amp sounds great now, hights or back, i also removed the series resistors in the supply.

Rudy

dmfraser · 15th July 2004, 04:05 PM

You do realize that because of the turn on voltages of the output devices that you are only going to be able to approach to within about 10V of the supply rails. That is, the output swing will be limited to about ±32V. This also means that if you play it at higher volume levels, the amp will run hotter than it could.

You either have to run the drivers at a higher supply rail voltage or supply a "bootstrap" setup to give the driver stage enough supply voltage to fully turn on the output devices.

The resistors in the DC sullpy rails between the bridge rectifier and the capacitors will also limit your power. They directly impact your damping factor as they slow down the ability for the filters to recharge on each half cycle of the AC. To get tight bass, you have to have as little impedance as possible between the power transformer and the speaker.

However, this does increase the peak current through the bridge which can cause noise. To prevent this, the usual practice is to put a .01uFd capacitor in parallel with each of the four diodes in the bridge.

R4 is fine. It provides a charge/discharge path for the input capacitor. This prevents a big thump from being passed through to the speaker if you plug or unplug the amplifier from the pre-amp with it switched on. The pole is low enpugh in fequency to have no effect on the sound.

Rudy · 15th July 2004, 04:19 PM

the voltage swing is about 35V@8E , witch i find fine
at 4E that will probebly will be a lot less, i know.

about the "bootstrap", that aint so easy with this kind off circuit, other supply was not an option.

about the resisitor ( accept for the fakt that they or gone ), they only limit the continuous power, not very important when just playing music, and they where indeed meant to limit inrush current and bridge noise.

Rudy

MikeB · 15th July 2004, 05:11 PM

@Rudy

"Wat worries me is that the hights or not as clear as i suspected"

Lucky you, with my design i have the problem of having too intense
trebles...

But, now having a cold, i don't hear any trebles, so problem is
temporaly fixed

Mike

15th July 2004, 04:05 PM	#13
dmfraser diyAudio Member Join Date: Dec 2003 Location: Orange County, CA	Comments You do realize that because of the turn on voltages of the output devices that you are only going to be able to approach to within about 10V of the supply rails. That is, the output swing will be limited to about ±32V. This also means that if you play it at higher volume levels, the amp will run hotter than it could. You either have to run the drivers at a higher supply rail voltage or supply a "bootstrap" setup to give the driver stage enough supply voltage to fully turn on the output devices. The resistors in the DC sullpy rails between the bridge rectifier and the capacitors will also limit your power. They directly impact your damping factor as they slow down the ability for the filters to recharge on each half cycle of the AC. To get tight bass, you have to have as little impedance as possible between the power transformer and the speaker. However, this does increase the peak current through the bridge which can cause noise. To prevent this, the usual practice is to put a .01uFd capacitor in parallel with each of the four diodes in the bridge. R4 is fine. It provides a charge/discharge path for the input capacitor. This prevents a big thump from being passed through to the speaker if you plug or unplug the amplifier from the pre-amp with it switched on. The pole is low enpugh in fequency to have no effect on the sound. __________________ Dan Fraser

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15th July 2004, 03:26 PM	#11
dimitri diyAudio Member Join Date: Oct 2002 Location: retired	Please imagine voltage source between K5 and K6, which will model your preamp. Or your preamp will have infinite output resistance?

15th July 2004, 03:51 PM	#12
Rudy diyAudio Member Join Date: Feb 2003 Location: Belgium	sos , i beleave i made a mistake, i mean R5 that pole you or talking about is outside the amp ? /edit, amp sounds great now, hights or back, i also removed the series resistors in the supply. Rudy

15th July 2004, 04:19 PM	#14
Rudy diyAudio Member Join Date: Feb 2003 Location: Belgium	the voltage swing is about 35V@8E , witch i find fine at 4E that will probebly will be a lot less, i know. about the "bootstrap", that aint so easy with this kind off circuit, other supply was not an option. about the resisitor ( accept for the fakt that they or gone ), they only limit the continuous power, not very important when just playing music, and they where indeed meant to limit inrush current and bridge noise. Rudy

15th July 2004, 05:11 PM	#15
MikeB diyAudio Member Join Date: Apr 2004 Location: Gütersloh	@Rudy "Wat worries me is that the hights or not as clear as i suspected" Lucky you, with my design i have the problem of having too intense trebles... But, now having a cold, i don't hear any trebles, so problem is temporaly fixed Mike