Until recently, toroid chokes having a sharp saturation characteristics were nonexistent. Now they're only hard to get at and a bit expensive (and single-sourced). Most toroids you'll see in class D amps produce a substantial amount of distortion. A normal gapped ferrite design is sublimely linear even if you buy the ferrite from a company called "Happy Sun and Shiny Weather Electrical Goods Trading Co. Ltd." or something of the sort.
Another reason why we don't like toroids is the fact that the windings are external. To get the same level of electrostatic shielding we're automatically getting from closed ferrites (grounded through the clip that holds the thing together) would require an extra metal box round the coil (remember that UcD's secret weapon is its unmatched ultralow EMI).
Also, the length of wire and hence the resistance is greater when using toroids.
For a given current and inductance, there is no size advantage to either toroids or ferrites. Ferrites are more flexible to tailor depending on the actual needs.
As a rule, we match coil current capability with that of the MOSFETs for an optimal design. Neither the coil nor the FETs are a bottle-neck.
Another reason why we don't like toroids is the fact that the windings are external. To get the same level of electrostatic shielding we're automatically getting from closed ferrites (grounded through the clip that holds the thing together) would require an extra metal box round the coil (remember that UcD's secret weapon is its unmatched ultralow EMI).
Also, the length of wire and hence the resistance is greater when using toroids.
For a given current and inductance, there is no size advantage to either toroids or ferrites. Ferrites are more flexible to tailor depending on the actual needs.
As a rule, we match coil current capability with that of the MOSFETs for an optimal design. Neither the coil nor the FETs are a bottle-neck.
Re: Re: Re: Re: Re: Acryl UcD case
Very simple, the spec says 26dB gain, 20db is a factor 10 and an additional 6dB is a factor 2 which gives me a factor 20. So with a 1.5V RMS signal you get 30V RMS which would be 42V peak output. 30V RMS corrsponds with 112W in 8 Ohm and 225W in 4 Ohm. So full power is achieved with 1.5V RMS input voltage.
Best regards
Gertjan
chrisb03 said:
How did you come up with that?
Very simple, the spec says 26dB gain, 20db is a factor 10 and an additional 6dB is a factor 2 which gives me a factor 20. So with a 1.5V RMS signal you get 30V RMS which would be 42V peak output. 30V RMS corrsponds with 112W in 8 Ohm and 225W in 4 Ohm. So full power is achieved with 1.5V RMS input voltage.
Best regards
Gertjan
Tangui said:
Hi Yves
You're wright , i've put back the 10k resistance since i got some power supply pumping effects sometimes
The 10K R has allowed me to bypass interstage caps again with reasonable 150mV max offset at the output , depending on potentiometer position ( at this level of dc offset , there's no pumping effect )
I just have less gain but still enough
in this configuration UCD+AD826with external power supply+no caps , the sound is simply magical
i simply regret to have not tried AD8620 with this power supply but i'm fed up testing op-amps
alain
Re: Which powersupply
Why not buy the softstart module directly from lcaudio? around 40€ and free shipping...
but you're allready ordering stuff from schuro, so maybe it won't make much difference.
Have you ordered things from schuro before? I was wondering what they charge for shipping to belgium...
richardkrol said:
Why not buy the softstart module directly from lcaudio? around 40€ and free shipping...
but you're allready ordering stuff from schuro, so maybe it won't make much difference.
Have you ordered things from schuro before? I was wondering what they charge for shipping to belgium...
Some of us live in shame....
For the past 10 years or so, I've been driving my Martin Logon CLSIIz with "Sample 104" this dear 30W amp was a prototype for Cambridge audio, which got rejected for "Weak Bass". Its retail price would have been about US$150 but featured High current REGULATED supplies, which gives it very good Bass Control and massive sound stage. Unfortunately it did not "interface" well with "Budget" speakers - which require "Loose" amplifier control to achieve their Boomy & bloated Bass.
The morel of this story, Current not "Watts" is need for Panel speakers.
For the past 10 years or so, I've been driving my Martin Logon CLSIIz with "Sample 104" this dear 30W amp was a prototype for Cambridge audio, which got rejected for "Weak Bass". Its retail price would have been about US$150 but featured High current REGULATED supplies, which gives it very good Bass Control and massive sound stage. Unfortunately it did not "interface" well with "Budget" speakers - which require "Loose" amplifier control to achieve their Boomy & bloated Bass.
The morel of this story, Current not "Watts" is need for Panel speakers.
Jocko Homo said:
now those people with their class As will be happy to listen to some guitar tunes, but they will have never heard the genie in Roger Water's "Three Wishes" when it starts rumbling down there in the 20-30hz range. Even at 300W/channel, the 3.5R bass panels weren't quite willing to keep up with it and the old mylar was just flapping in the wind.
Now I have 600W/channel (into 4ohm) and things have firmed up quite a bit - almost to be happy with the amps. There's plenty of current in both amps and 720,000uF of capacitors do their best to feed the bass when its hungy. I know of several owners who have moved to about 1.4kw/channel and they have reported significant changes in performance that made the move worth while.
There are folks out there feeding their maggies an 8 watt tube signal, but they are either running the excuse-maggie MMGs or they don't expect to hear a bass below 100hz
You can power maggies with a 1980s Aiwa 20watt receiver and get them to be "loud" but that's not quite the same as making them sound right. Sooner or later you'll see that having huge current reserves is what makes them sing.
Anyway - if there was a 1000W module available before December, I'd buy two of those plus the 400s for the other two channels.
Peter
UcD400 is available
Hello ,
I do not know if I am aloud to inform everybody this;
The UcD400 is available!!!!
Regards,
Jan-Peter
www.hypex.nl
Hello ,
I do not know if I am aloud to inform everybody this;
The UcD400 is available!!!!
Regards,
Jan-Peter
www.hypex.nl
Jam,
We deliver also the JST connectors with the UcD400 so this would be no problem.
The heavier UcD700 will be our next project, at the end of the year I will know more when this could be available.
For an OEM customer we are designing a Full Bridge version, the first proto is very promising.
Class-D developing needs time..........Please do have some patience
Regards,
Jan-Peter
www.hypex.nl
We deliver also the JST connectors with the UcD400 so this would be no problem.
The heavier UcD700 will be our next project, at the end of the year I will know more when this could be available.
For an OEM customer we are designing a Full Bridge version, the first proto is very promising
.Class-D developing needs time..........Please do have some patience
Regards,
Jan-Peter
www.hypex.nl
Paul:
Just because they "sound better" with a higher power amp does not mean that they actually need it. You can not equate performance with power output capabilities.
And no.......I don't expect to hear much below 100 Hz, as that is the frequency that mine starts to roll off at 6 dB/octave. Won't matter what amp I have.
Unless it is the one that I built with a shelving EQ in it. That one would require more power. Whether or not it would melt the panel is another subject.
Jam:
Zero. Never tried to. You already know that, don't you.
Jocko
Just because they "sound better" with a higher power amp does not mean that they actually need it. You can not equate performance with power output capabilities.
And no.......I don't expect to hear much below 100 Hz, as that is the frequency that mine starts to roll off at 6 dB/octave. Won't matter what amp I have.
Unless it is the one that I built with a shelving EQ in it. That one would require more power. Whether or not it would melt the panel is another subject.
Jam:
Zero. Never tried to. You already know that, don't you.
Jocko
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