Re: Bass guitar amplifier
I have Wilson Audio Watt/Puppy 6 speakers and my usual amp is a Threshold S/500 II. I wrote a short review about my experiences so far with the Zappulse amps and various PSU configurations here:
http://www.diyaudio.com/forums/showthread.php?postid=554984#post554984
Joep Zonnebloem said:
I have Wilson Audio Watt/Puppy 6 speakers and my usual amp is a Threshold S/500 II. I wrote a short review about my experiences so far with the Zappulse amps and various PSU configurations here:
http://www.diyaudio.com/forums/showthread.php?postid=554984#post554984
Sync board?
I'm in the process of building a 6-channel power amp (or maybe 2 three-channel blocks) for my monster speakers (see my thread on dipole line arrays).
I've already bought 6 2.2SE modules through the Italian distributor and I was waiting for a suitable sync module before starting the actual building of the amp.
From what I've been able to see on the LC site, if you use more than a couple of modules in the same enclosure (or even in the same house, for that matter!) you are "strongly recommended" to use some sort of synchronization of the modules.
For a short time LC had a module for sale on their site but, besides the cost being outrageously high, apparently it created more problems than it solved (some high-frequency ringing or harshness of sound), so that it has been withdrawn.
However, I definitely need to find a way to synchronize the modules (at least so I'm told) before even starting to build my amp.
Has anybody here a good solution for it?
Lars, what is the status of LC on designing the new module?
What are the issues of using a "traditional" oscillator like the one that is suggested somewhere on the LC documentation?
While I wait for this issue to be solved, I'll start experimenting with Karsten Madsen's (CadAudio) modules. I have to build a small amp for my kids, I'll give them a try.
I'm in the process of building a 6-channel power amp (or maybe 2 three-channel blocks) for my monster speakers (see my thread on dipole line arrays).
I've already bought 6 2.2SE modules through the Italian distributor and I was waiting for a suitable sync module before starting the actual building of the amp.
From what I've been able to see on the LC site, if you use more than a couple of modules in the same enclosure (or even in the same house, for that matter!) you are "strongly recommended" to use some sort of synchronization of the modules.
For a short time LC had a module for sale on their site but, besides the cost being outrageously high, apparently it created more problems than it solved (some high-frequency ringing or harshness of sound), so that it has been withdrawn.
However, I definitely need to find a way to synchronize the modules (at least so I'm told) before even starting to build my amp.
Has anybody here a good solution for it?
Lars, what is the status of LC on designing the new module?
What are the issues of using a "traditional" oscillator like the one that is suggested somewhere on the LC documentation?
While I wait for this issue to be solved, I'll start experimenting with Karsten Madsen's (CadAudio) modules. I have to build a small amp for my kids, I'll give them a try.
Big Power Supply: GregD
Hi Greg, I read your findings and my jaws hurt from smiling, you're really a freak! I like the way you talk about sound. And so far I had only read about capacitors for the Zap module of around max 33000 mF, so you decided that it had to be some 10 times as much, that is cool, same as the 1500VA PSU's. And, while I think of it : the only thing a digital "amplifier" has to do is to control the power by means of the processed signal (sound); it has nothing to do with amplifying the signal itself.
So it makes sense to look at a PSU as a basic starting point, instead of just a component.
Hi Greg, I read your findings and my jaws hurt from smiling, you're really a freak! I like the way you talk about sound. And so far I had only read about capacitors for the Zap module of around max 33000 mF, so you decided that it had to be some 10 times as much, that is cool, same as the 1500VA PSU's. And, while I think of it : the only thing a digital "amplifier" has to do is to control the power by means of the processed signal (sound); it has nothing to do with amplifying the signal itself.
So it makes sense to look at a PSU as a basic starting point, instead of just a component.
Re: Big Power Supply: GregD
In the project that I am working on (using the 2.2SE modules for subwoofer power) it was recommended by Lars at LC that for low frequency and low impedance loads (2-4 Ohms) that the PS be able to handle 400VA per module and large caps. I used 82,000mF for the caps. I haven't been able to put the amp through a serious work out due to a mysterious 100K oscillation in the modules but it seems like it can produce an output and sound that will make anyone smile.
Now if we only get a SMPS to replace the boat anchor torroidal transformer and the beer can size caps we would really have something.
tgb
GregD said:
Joep Zonnebloem said:
In the project that I am working on (using the 2.2SE modules for subwoofer power) it was recommended by Lars at LC that for low frequency and low impedance loads (2-4 Ohms) that the PS be able to handle 400VA per module and large caps. I used 82,000mF for the caps. I haven't been able to put the amp through a serious work out due to a mysterious 100K oscillation in the modules but it seems like it can produce an output and sound that will make anyone smile.
Now if we only get a SMPS to replace the boat anchor torroidal transformer and the beer can size caps we would really have something.
tgb
Re: Big Power Supply: GregD
Jaap, modify/upgrade any audio equipment....90% of the upgrades involve the power supply section. Also plenty of commercial available upgrades concentrate on power supply. This is the case with digital sources, amplifiers, phono pre's....anything.
Class D is not a Digital amplifier, it is analog! (a TACT milenium is an example of a digital amplifier)
Joep Zonnebloem said:
Jaap, modify/upgrade any audio equipment....90% of the upgrades involve the power supply section. Also plenty of commercial available upgrades concentrate on power supply. This is the case with digital sources, amplifiers, phono pre's....anything.
Class D is not a Digital amplifier, it is analog! (a TACT milenium is an example of a digital amplifier)
I recently ordered two zap pulse modules and a predator power supply that I am still waiting for... and now I am getting worried.
I was thinking of using two 40V 500VA transformers which should be ok?
Could I add four capacitors after the predator supply? Two on each channel? Do you think it would make any difference?
I am not the biggest hi-fi guy, but I have been working in recording studios for quite a while and been building my own high end compressors and mic preamps, so I know what sounds good.
I love good sound, but my stereo is not the best, but it still sounds good. That is bassically what I am looking for in the zap as well, a good sound without spending too much money.
So, what is worth investing in
Thanks
Robert
I was thinking of using two 40V 500VA transformers which should be ok?
Could I add four capacitors after the predator supply? Two on each channel? Do you think it would make any difference?
I am not the biggest hi-fi guy, but I have been working in recording studios for quite a while and been building my own high end compressors and mic preamps, so I know what sounds good.
I love good sound, but my stereo is not the best, but it still sounds good. That is bassically what I am looking for in the zap as well, a good sound without spending too much money.
So, what is worth investing in
Thanks
Robert
A couple of things that I am sure of at this point are to separate the modules and give each one its own power supply. Since you already plan to use two transformers, all you'd need is four bridge rectifiers, say 4 10,000uf electrolytics, and if you like, 16 68nf capacitors for the bridge rectifiers for noise reduction. All of this combined should cost much less than one Predator power supply, and is pretty easy to wire up point to point. The 4 electrolytics aren't too expensive, will give you double the capacitance of the Predator PSU, and are at least a good place to start. You can always parallel more capacitors later.
I'd also stick each Zappulse in its own box as well. I really didn't like having the two modules next to each other on the Predator power supply. Channel separation was poor, and they made annoying whiny noises when turning off.
Beyond that, hopefully I'll have a better idea in the next couple of weeks.
I'd also stick each Zappulse in its own box as well. I really didn't like having the two modules next to each other on the Predator power supply. Channel separation was poor, and they made annoying whiny noises when turning off.
Beyond that, hopefully I'll have a better idea in the next couple of weeks.
That's completely normal behaviour and nothing wrong with that. See below (from earlier in the thread):GregD said:
michaelab said:
...and in response:
Lars Clausen said:
In fact, Lars recommends you don't build monoblocks at all:
From this page on the LC Audio site:
Michael.
Michaelab is right, the LC site strongly discourages from building separate monoblocks and/or using separate non-synced modules on the same power line.
They say that the interference could travel through the live/neutral/earth wires and that there's no sure way to prevent this from happening.
Hence my previous post about synchronization modules: they claim that the best s/n ratios are obtained when all the modules work in sync.
The added benefit of using an external synchronization module is that it is possible to change the oscillating frequency of the module from the approx. 400KHz standard setup up to almost 1MHz. I' would be interested in finding out what are the sonic effects of such a change.
Has anybody tried it?
They say that the interference could travel through the live/neutral/earth wires and that there's no sure way to prevent this from happening.
Hence my previous post about synchronization modules: they claim that the best s/n ratios are obtained when all the modules work in sync.
The added benefit of using an external synchronization module is that it is possible to change the oscillating frequency of the module from the approx. 400KHz standard setup up to almost 1MHz. I' would be interested in finding out what are the sonic effects of such a change.
Has anybody tried it?
I also read the posts by Lars about not building monoblocks, but when I had the two modules right next to each other I found the channel separation to be unacceptable with a very flat soundstage. Connecting the ground planes together on the modules made no difference for separation, and I don't remember if there was any difference regarding the whiny noise on shutdown. Also, even though the whiny noise is normal, it still bothered me a bit.m.parigi said:
To prevent the power line issues, I put Schaffner FN9222 IEC filter sockets on the amps primarily to prevent switching noise from getting out of the amps as well as any noise from getting in. I figured that we're basically trying to filter out the same kind of noise that switching power supplies generate.
I would also be curious about the sonic effects of moving the oscillating frequency up to 1MHZ, but without changing the output filter to take advantage of this, I don't see why the sound would change.
There is no need to change the output filter as it will 'take advantage' of the increased switching frequency by having more attenuation of the switching frequency.
However, increasing the switching frequency is not automatically a good thing as it results in more losses and the driving stage has to be up to the task of the increased charge/discharge requirements. I believe Lars recommends to leave well alone here.
However, increasing the switching frequency is not automatically a good thing as it results in more losses and the driving stage has to be up to the task of the increased charge/discharge requirements. I believe Lars recommends to leave well alone here.
michaelab said:
How far apart are the modules from each other? When I tried this the modules were only separated by a few millimeters to a couple of centimeters. Or maybe the difference is in the power supply. I only tried the Zaps in this configuration with the Predator PSU. A couple of other people who listened to the amps weren't bothered by the lack of separation, but it bothered me from the moment I started listening.
As a fair approximation, as the filter is 12dB/oct and you are roughly doubling the frequency, the attentuation will be roughly 12dB more than at the original frequency.
I say again however, that increasing the frequency could actually worsen performance due to increased losses and tighter rise/fall time requirements.
I say again however, that increasing the frequency could actually worsen performance due to increased losses and tighter rise/fall time requirements.
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