ULD Extreme
Terry
Many recent amplifiers have an extended low frequency response to minimise the source impedance seen by the input transistors.
This is also explained in the SC article. (August 2008 p.25)
Very few CDs, except some audiopile types have any real LF content below 20HZ. Infrasonics from warped LPs etc. may be better dealt with by the phono preamp?
Alex
Terry
Many recent amplifiers have an extended low frequency response to minimise the source impedance seen by the input transistors.
This is also explained in the SC article. (August 2008 p.25)
Very few CDs, except some audiopile types have any real LF content below 20HZ. Infrasonics from warped LPs etc. may be better dealt with by the phono preamp?
Alex
Thanks Alex, I agree with your comments until you get to Home Thearter at which time all bets are off.
It is very easy to think in terms of "what I want should be what everyone wants." As a counsellor I know that this is part of human nature. I would like, just once, for a more generic approach to an amp design, something that almost anyone could use for whatever purpose. Imagine for example that someone wishes to use this board for active multiway speakers, oh, and we have the ability on board to set xover points by adjusting the components at the input.
I just think a more generic approach has much wider appeal. As far as I can see it has not been done before.
Terry
It is very easy to think in terms of "what I want should be what everyone wants." As a counsellor I know that this is part of human nature. I would like, just once, for a more generic approach to an amp design, something that almost anyone could use for whatever purpose. Imagine for example that someone wishes to use this board for active multiway speakers, oh, and we have the ability on board to set xover points by adjusting the components at the input.
I just think a more generic approach has much wider appeal. As far as I can see it has not been done before.
Terry
Carl,
Nice drafting, looks real good. What's the software, Carl?
I oppose Terry's suggestion of a high pass filter. They introduce needless phase shifts. They were important once with LP records, to remove rumble, but no longer since sub 16Hz signals are never recorded on CD/DVD.
However, I do like the low pass filter, to stop EMI getting into the amp from the input. I have noticed Magneplanars make a very effective radio antenna, and a 3.3nF cap across the output of the amp prevents radio stations entering the amp through the speaker and its interconnects.
This assumes the amp can tolerate 3.3nF across its output. This cap introduces some phase shift; my limited contact with this amp, however, demonstrates it may not like this cap.
The 6dB corncer should be around 160KHz, though, where phase shifts at 20KHz are not marked. 820pF and 100R are a bit low; 6dB is at about 1.9MHz!! The 100R should be amended to 1K.
Hugh
Nice drafting, looks real good. What's the software, Carl?
I oppose Terry's suggestion of a high pass filter. They introduce needless phase shifts. They were important once with LP records, to remove rumble, but no longer since sub 16Hz signals are never recorded on CD/DVD.
However, I do like the low pass filter, to stop EMI getting into the amp from the input. I have noticed Magneplanars make a very effective radio antenna, and a 3.3nF cap across the output of the amp prevents radio stations entering the amp through the speaker and its interconnects.
This assumes the amp can tolerate 3.3nF across its output. This cap introduces some phase shift; my limited contact with this amp, however, demonstrates it may not like this cap.
The 6dB corncer should be around 160KHz, though, where phase shifts at 20KHz are not marked. 820pF and 100R are a bit low; 6dB is at about 1.9MHz!! The 100R should be amended to 1K.
Hugh
ULD Extreme
Terry
There is nothing stopping anybody from reducing the value of the Input capacitors. .Many people will opt to replace the higher value bipolar caps with much lower value polypropylene capacitors anyway. We also have to be mindful of the additional costs involved in PCB manufacture, and the possibility of either needing more real estate, or cramping things up to make additional room.
Alex
Hugh
I strongly disagrree with your suggestion to reduce the input filter bandwidth. I have been able to hear clear benefits from much wider bandwidths than 6dB down at 160kHZ.
Alex
Terry
There is nothing stopping anybody from reducing the value of the Input capacitors. .Many people will opt to replace the higher value bipolar caps with much lower value polypropylene capacitors anyway. We also have to be mindful of the additional costs involved in PCB manufacture, and the possibility of either needing more real estate, or cramping things up to make additional room.
Alex
Hugh
I strongly disagrree with your suggestion to reduce the input filter bandwidth. I have been able to hear clear benefits from much wider bandwidths than 6dB down at 160kHZ.
Alex
Carl_Huff said:
Hi Carl, thought you may be in bed by now.
Does it hurt to put such provision on the board. Having a dedicated device increases costs due to duplication of PS and enclosures, is more prone to impedence mis match and has low wife factors.
As a speaker designer I know filters are capable of so much when dealing with typical speakers. IMHO every amp should have such a provision especially when the DIY guy can set the amp and speaker combination up to be a perfect symbiotic relationship.
Terry
This is amp design, guys, not carving up Europe after a war........
Most of our evidence, including my own, is ancecdotal, and up for challenge regardless.
My opinion remains my opinion, and it is up to the listener to decide if he agrees or not. Nothing more obvious than that.
Terry,
Speaker designers who routinely design for sub 2 ohm impedances show little regard for the laws of physics. Amps designed to handle these loads with safety almost never sound good. I'm with you, cooperation would be marvellous, but it's likely not going to happen.
Hugh
Most of our evidence, including my own, is ancecdotal, and up for challenge regardless.
My opinion remains my opinion, and it is up to the listener to decide if he agrees or not. Nothing more obvious than that.
Terry,
Speaker designers who routinely design for sub 2 ohm impedances show little regard for the laws of physics. Amps designed to handle these loads with safety almost never sound good. I'm with you, cooperation would be marvellous, but it's likely not going to happen.
Hugh
Re: Re: ULD Extreme
Terry
My old DCM QED speakers supposedly go down to 25HZ, and with these speakers which have a minimum impedance of 8 ohms, and a sensitivity of 87dB/1W/1M, I find they sound better with a lower amplifier rolloff point. Only a couple of my CDs go much lower than 20HZ
Alex
pheonix358 said:
Terry
My old DCM QED speakers supposedly go down to 25HZ, and with these speakers which have a minimum impedance of 8 ohms, and a sensitivity of 87dB/1W/1M, I find they sound better with a lower amplifier rolloff point. Only a couple of my CDs go much lower than 20HZ
Alex
Re: Re: Re: ULD Extreme
Alex, then for you this may not be necessary, although a 15 Hz 2nd order filter may do wonders. The point is why not accept that others may be able to make good use of such a filter. Not every one owns speakers with real output at 25 Hz.
Why stop others who may want such a provision.
Terry
sandyK said:
Alex, then for you this may not be necessary, although a 15 Hz 2nd order filter may do wonders. The point is why not accept that others may be able to make good use of such a filter. Not every one owns speakers with real output at 25 Hz.
Why stop others who may want such a provision.
Terry
Hugh,
I am using SPlan 6.0 from http://www.abacom-online.de for schematics and I use Sprint Layout 5.0 from the same vendor for PCB layout. Both programs are very inexpensive and fully featured. The only downer is that netlists are not supported. When PCBs get busy and dense I have to fall back on Protel.
I am using SPlan 6.0 from http://www.abacom-online.de for schematics and I use Sprint Layout 5.0 from the same vendor for PCB layout. Both programs are very inexpensive and fully featured. The only downer is that netlists are not supported. When PCBs get busy and dense I have to fall back on Protel.
UJLD Extreme
Terry
Perhaps it may be better for some talented designer to come up with a nice little auxiliary PCB, which could perhaps be mounted inside a diecast aluminium box inside the amplifier case, AND include niceties such as larger ,quality polypropylene or teflon input capacitors, as well as the input tailoring you are proposing ?That 47uF bipolar input capacitor really is a limiting factor, and there simply isn't room on the PCB for something much better.
Alex
Terry
Perhaps it may be better for some talented designer to come up with a nice little auxiliary PCB, which could perhaps be mounted inside a diecast aluminium box inside the amplifier case, AND include niceties such as larger ,quality polypropylene or teflon input capacitors, as well as the input tailoring you are proposing ?That 47uF bipolar input capacitor really is a limiting factor, and there simply isn't room on the PCB for something much better.
Alex
Re: UJLD Extreme
Thanks Sandy, that is usually what has to be done, but it sucks
Why is it so hard to listen to the requirements that should apply to all amps. After all, what are amps used for ..... yes, to run speakers. Listen to the speaker guys, it is important so we can get the best sound possible with our individual and much loved set ups.
I feel like an apple tree in a banana plantation.
Terry
sandyK said:
Thanks Sandy, that is usually what has to be done, but it sucks
Why is it so hard to listen to the requirements that should apply to all amps. After all, what are amps used for ..... yes, to run speakers. Listen to the speaker guys, it is important so we can get the best sound possible with our individual and much loved set ups.
I feel like an apple tree in a banana plantation.
Terry
Terry,
Not to 'poo-poo' all your ideas but it would appear that you are the only party interested in a 4th pair of outputs. To that end my suggestion is that I supply you with the '.LAY' PCB file and you add the output pair yourself. Don't forget the 5W emitter resistors. Does that sound good to you?
Not to 'poo-poo' all your ideas but it would appear that you are the only party interested in a 4th pair of outputs. To that end my suggestion is that I supply you with the '.LAY' PCB file and you add the output pair yourself. Don't forget the 5W emitter resistors. Does that sound good to you?
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