Bi-amping and power supply elco's

edm · 14th February 2003, 07:22 AM

Normally for an amp the rule for power supply elco's is buy as much as your wallet allows you to, right?

But i was wondering if this 'rule' also holds for the amp that drives the high section. The amount of power that needs to be delivered is substantially lower, so my guess would be that the total capacity could also be lower.

Can somebody shed some light on this matter why I should or should not lower the amount of capacity in the high section.

Emiel

Jay · 14th February 2003, 11:54 AM

I think you get it right. But not all amplifier PS expects high capacitance. For some circuit, the capacitance may harm the transistor or create unwanted voltage on the bridge diode. For all amplifiers though, there is a point where capacitance addition will give no benefit.

It relatively doesn’t need high voltage or current to amplify high frequencies than to amplify lows. But, are you talking about bi-amping, Emiel? I think the amp specs should have been different from the beginning.

edm · 14th February 2003, 02:33 PM

Yep I am talking about bi-amping. Why should the amp specs be that different?

tiroth · 14th February 2003, 02:48 PM

Well, since we expect to drive only higher frequencies we might choose an amp design with higher slewrate, Class A vs. AB, etc.

Since the output power is lower, certainly the max current and possibly the bias is lower, which means the power supply need not be as robust.

It all depends on the design, though. A 20W Class-A design might need a better supply than a 100W A/B, especially depending upon the impedances targeted.

Bobken · 14th February 2003, 03:56 PM

Hi,

In addition to what the others have already said, it is usual to need a fairly hefty bank of reservoir caps to give plenty of 'wallop' at the lower frequencies, but it is also important to have a good smooth supply for the HF amp, as this will otherwise be more readily noticed as a harsher and less smooth sound at HF.

Therefore, even if you try to get way with less capacitance in the HF amp, good quality low ESR (at HF) caps are a good idea here.

Regards,

djmiddelkoop · 15th February 2003, 04:45 AM

It also depends on the way the output device is connected:

with collector/drain to power-supply you need a lot, like 20kuF.

with emittor/source connected to power-supply you need less, like 4700uF.

14th February 2003, 07:22 AM	#1
edm diyAudio Member Join Date: Nov 2002 Location: The top of the Netherlands	Bi-amping and power supply elco's Normally for an amp the rule for power supply elco's is buy as much as your wallet allows you to, right? But i was wondering if this 'rule' also holds for the amp that drives the high section. The amount of power that needs to be delivered is substantially lower, so my guess would be that the total capacity could also be lower. Can somebody shed some light on this matter why I should or should not lower the amount of capacity in the high section. Emiel

14th February 2003, 03:56 PM	#5
Bobken diyAudio Member Join Date: Dec 2002 Location: UK	Hi, In addition to what the others have already said, it is usual to need a fairly hefty bank of reservoir caps to give plenty of 'wallop' at the lower frequencies, but it is also important to have a good smooth supply for the HF amp, as this will otherwise be more readily noticed as a harsher and less smooth sound at HF. Therefore, even if you try to get way with less capacitance in the HF amp, good quality low ESR (at HF) caps are a good idea here. Regards, __________________ Bob

15th February 2003, 04:45 AM	#6
djmiddelkoop diyAudio Member Join Date: Feb 2003 Location: Noord-Holland	It also depends on the way the output device is connected: with collector/drain to power-supply you need a lot, like 20kuF. with emittor/source connected to power-supply you need less, like 4700uF. __________________ Music is the best F.Z.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Nippon elco 12.000/63V - Interesting?	Tarasque	Swap Meet	7	23rd September 2007 10:44 PM
OPTs and power for bi-amping	jnb	Tubes / Valves	2	5th June 2007 07:46 AM
RAIL power supply / BI Amping question	Bifi01	Solid State	4	24th August 2004 06:02 AM
Fischer & Tausche Elco's	cHoc	Parts	1	5th June 2003 09:15 PM
PHILIPS BC Elco's	Piersma	Parts	48	2nd June 2003 12:29 AM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

14th February 2003, 11:54 AM	#2
Jay diyAudio Member Join Date: Feb 2003 Location: Jakarta	I think you get it right. But not all amplifier PS expects high capacitance. For some circuit, the capacitance may harm the transistor or create unwanted voltage on the bridge diode. For all amplifiers though, there is a point where capacitance addition will give no benefit. It relatively doesn’t need high voltage or current to amplify high frequencies than to amplify lows. But, are you talking about bi-amping, Emiel? I think the amp specs should have been different from the beginning.

14th February 2003, 02:33 PM	#3
edm diyAudio Member Join Date: Nov 2002 Location: The top of the Netherlands	Yep I am talking about bi-amping. Why should the amp specs be that different?

14th February 2003, 02:48 PM	#4
tiroth diyAudio Member Join Date: Dec 2001 Location: Pittsburgh, PA, USA	Well, since we expect to drive only higher frequencies we might choose an amp design with higher slewrate, Class A vs. AB, etc. Since the output power is lower, certainly the max current and possibly the bias is lower, which means the power supply need not be as robust. It all depends on the design, though. A 20W Class-A design might need a better supply than a 100W A/B, especially depending upon the impedances targeted.

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read