View Full Version : Velleman K4010
Filterlab
04-03-2008, 12:36
Stumbled upon this auction on ebay and did a little digging: Velleman K4010 300w Mosfet mono amps (pair) (http://cgi.ebay.co.uk/velleman-300w-mono-mosfet-amps-two-of_W0QQitemZ130203125914QQihZ003QQcategoryZ14973QQ ssPageNameZWDVWQQrdZ1QQcmdZViewItem).
Anyone built a Velleman amp before, if so how good was it?
StanleyB
04-03-2008, 21:51
That's one of the best power amp kits I know of. It started as a project in Elektor magazine. They also did a 100W version 1st, which called the Cressendo. I actually started collecting some of the bits at one stage, but other projects got in the way. It uses the Hitachi MOSFETs that were also used in the Hitachi HA-7500 power amps. The HA-7500 is one of the best sounding amp to come out of Japan in the 80's, but very much under designed and under powered. The Elektor project was a fast improvement over the Hitachi design and showed what could be achieved with MOSFET. I don't think that the Elektor design has ever been bettered in even a commercially available MOSFET amp. The Velleman kit is the hardware from the Elektor project. If you like building power amp projects, you'll love completing this one. You can get some suitable heatsinks from RS to match the brute and create a gorgeous looking external finish. Forget fitting the VU meters that comes with the kit.
greenhomeelectronics
04-03-2008, 22:05
I have to agree with Sensimilia, we had one in stock a while back, it was a damn fine amp. the one we had used twin toroidal based psu's, the guy that bought it did a few mods and was delighted with it. It's pretty simple but well designed and pretty rugged.
Filterlab
04-03-2008, 22:42
Now that's interesting, may be worth picking up for a few quid and having a bash, not as a permanent amp replacement, but as a DIY job it could be fun and it doesn't look vastly complicated.
StanleyB
04-03-2008, 23:00
Just observe the appropriate anti static precautions when handling the MOSFETs. Don't be fooled by the apparent simple design. The differential input stage and fully complementary design offers some eye watering performance. The dual toroidal power supply for each channel is the most advanced transformer layout and wiring I have ever seen in any power amp. If you take the time to do a good job on the case design that you are happy with you could be in for a treat.
Go to http://www.schaeffer-ag.de/index.php?id=97&L=1 for some great inspiration on your own case design and free software to design your own front panel etc.
Filterlab
04-03-2008, 23:04
Cool, cheers for that. I may just have a go, I have an anti-static strap from when I swapped a load of components in the works PCs. Cheers for the link too, some nice gear on there. Oooo, my DIY juices are flowing. ;)
Vinyl Grinder
04-03-2008, 23:59
Go to http://www.schaeffer-ag.de/index.php?id=97&L=1 for some great inspiration on your own case design and free software to design your own front panel etc.
Those pannels are first rate.I had a load made for a modular synthersizer rig i once made..I think Myst used to use these for there amp facias..tad pricey but worth it.
Filterlab
05-03-2008, 08:46
Yeah they look very nice, and a power amp may demand more than a cherry box and four slices of beech.
:)
StanleyB
05-03-2008, 10:06
My apologies for the cost, time and effort my replies could well be costing you:).
Vinyl Grinder
05-03-2008, 10:31
Yeah they look very nice, and a power amp may demand more than a cherry box and four slices of beech.
:)
Here goes rob Myst pre, i'm positive this is a Schaeffer front pannel
http://i275.photobucket.com/albums/jj292/ELPFAN/a3d5_3.jpg
Filterlab
05-03-2008, 13:04
My apologies for the cost, time and effort my replies could well be costing you:).
I have plenty of reserves for all three. :)
Never been a big fan of mosfets but it would make a decent first time diy project for the price, the price for the components alone would cost must more than what the current bid is
You could build it and probably sell it on for not no loss if you didn't like it, be a good bit of experience for you too
Filterlab
07-03-2008, 10:48
My thinking exactly mate, I'm not a complete novice but I'm nowhere near the same level as you! Would be fun to learn but I won't test it with my £2k speakers just in case I've bodged something. :)
Well no better way to improve experience than getting the hands dirty;)
Could also make an interesting thread, if you struggle with anything I'm sure theres enough on here to give help/advice if needed
What I tend to do with amps is measure for DC offsets, set the bias and then soak test them on a pair of high powered 8ohm loading resistors, plug in the sig gen and have a look at the outputs on a scope etc.
Main thing to do though is check the voltages, DC offset and correct setting of the bias which can easily be done with a multimeter
I'm trying to find the schematic for this amp, seems it has speaker protection on the output too http://www.esr.co.uk/velleman/products/index_kit.htm
http://www.esr.co.uk/velleman/images/k4010.jpg
Filterlab
07-03-2008, 11:53
Indeed, and a soft start too.
Those power fets from Hitachi are marvellous. But the guys designing the Crescendo spoiled the possible result. I think they had a problem with stability and decided to filter it so the bandwidth is rather small.
In the end the design is reliable but it surely is not a High End design. You may find a better one (with the same transistors) at A-50 (http://www.hawkaudio.nl/amplifiers/a50eng.html). There is full documentation available at the download pages of that site.
The bidding ended at £114.55 , reserve not met.
So much for it being a cheap project:confused:
Filterlab
11-03-2008, 15:40
Listed again though, his reserve must be almost as high as the retail price! :confused:
Never been a big fan of mosfets but it would make a decent first time diy project for the price, the price for the components alone would cost must more than what the current bid is
You could build it and probably sell it on for not no loss if you didn't like it, be a good bit of experience for you too
I produced the first non Toshiba application note mosfet output power amp, the Tresham Audio SR402 in 1980. A high powered PA / studio monitor amp, and that in my opinion are the only applications they are suitable for. For high power and endurance applications they are perfect as they self protect, as in instead of decreasing resistance between base and emitter and going into thermal runaway the way a normal bi-polar transistor does when demanded to be used outside its operating envelope, resistance across the gate of a mosfet increases to the point where the device shuts down. So it self protects. But for hi-fi applications mosfets have serious deficiencies. It is impossible to produce balanced pairs due to crystal growing properties and problems, the *on* resistance and other properties are very different between the + and - devices. This makes class B or AB designs have non linear properties that are clearly audible. Class A is a distinct possibility and for single ended class A transistor work they are about the only safe option.
Sorry I am a silly arse, should read Hitachi not Toshiba. Well it was 28 years ago :(
I produced the first non Toshiba application note mosfet output power amp, the Tresham Audio SR402 in 1980. .
StanleyB
12-03-2008, 11:33
Why are some engineers quick to blame the parts when it is really their ability that is at fault? The classic one so often heard is: "if I had a bigger knob I would be a better lover" :mental:.
I use 3 semiconductors in my product that most engineers complain about in terms of performance they are able to extract from those parts. I don't have any problem with getting them to work properly, and bring delight to the ears of many. Does that make me a genius or my fellow engineers a bunch of circuit copiers who should be taking up a different trade?
I got a set of emails stored away from a guy who I asked to carry out a certain mod on something he bought off me. He gave me a whole lecture about why it won't work, and how I was a useless quack pretending to be a designer. He was a top engineer with a big US electronics company and had designed components used by NASA. So I asked him to back up his claims that the thing would blow up if he did it the way I told him to. If it blew up, I would give him a refund and a new unit FOC.
Two days later a had one long apologetic email about how smart I was and how much he appreciated my patience. And he was over the moon big time with the results.
The moral of the story is that some engineers won't know what to do with a bigger knob:smoking:.
Why are some engineers quick to blame the parts when it is really their ability that is at fault? The classic one so often heard is: "if I had a bigger knob I would be a better lover" :mental:.
I use 3 semiconductors in my product that most engineers complain about in terms of performance they are able to extract from those parts. I don't have any problem with getting them to work properly, and bring delight to the ears of many. Does that make me a genius or my fellow engineers a bunch of circuit copiers who should be taking up a different trade?
I got a set of emails stored away from a guy who I asked to carry out a certain mod on something he bought off me. He gave me a whole lecture about why it won't work, and how I was a useless quack pretending to be a designer. He was a top engineer with a big US electronics company and had designed components used by NASA. So I asked him to back up his claims that the thing would blow up if he did it the way I told him to. If it blew up, I would give him a refund and a new unit FOC.
Two days later a had one long apologetic email about how smart I was and how much he appreciated my patience. And he was over the moon big time with the results.
The moral of the story is that some engineers won't know what to do with a bigger knob:smoking:.
You obviously haven't a clue about the basic properties of transistors.
Crystals are grown and different crystals grow differently and have different properties, both advantages and disadvantages. Everything in audio design is setting preferences and making compromises. A power fet amp from the hands of an intuitive and capable of listening designer will clearly out perform a bi-polar design from a designer who isn't. My point is all other things being equal fets have severe problems in terms of linearity and balance. It can be seen quite clearly on an oscilloscope and can be heard quite clearly. This non linearity is endemic and incurable with the present semi conductor state of the art.
BUT things change, we had to start with germanium crystals and really couldn't get going until we grew silicon crystals. Fets will give you the ultimate in transistor linearity if you configure them for single ended class A as long as you put up with the compromises that design inflicts. Very low power levels and need for high heat dissipation. And the shear advantage of a device that doesn't go crack splutter bang and loads of smoke from the burnt out emitter resistors when grossly overloaded or short circuited is well worth having. The manufacturers of power fets have been trying for years to get over these non linearity problems in the growth of the crystals, so far with little success otherwise they would have taken over from bi-polar the same way as silicon took over from germanium.
StanleyB
12-03-2008, 17:37
You obviously haven't a clue about the basic properties of transistors.
:lol:
There we go again. Don't blame the properties of the transistors. Do you complain about the properties of valves as well? Your comments only go to underline what I am stating that many engineers are brainwashed with: blame the tools they have to work with for not being able to produce a better end product. The reasons tend to be obvious in many cases. If you start thinking out of the box instead of trying to build the same structural design day in and day out, new components are not going be be any good to you. You are supposed to use the properties of the new part to your advantage.
In the case of MOSFETS, amplifier designers rushed out and designed class B amps in the believe and hope that it would sound better. How many people outside Japan started from scratch and looked at ways to design new types of audio amps circuitry?
:lol:
There we go again. Don't blame the properties of the transistors. Do you complain about the properties of valves as well? Your comments only go to underline what I am stating that many engineers are brainwashed with: blame the tools they have to work with for not being able to produce a better end product. The reasons tend to be obvious in many cases. If you start thinking out of the box instead of trying to build the same structural design day in and day out, new components are not going be be any good to you. You are supposed to use the properties of the new part to your advantage.
In the case of MOSFETS, amplifier designers rushed out and designed class B amps in the believe and hope that it would sound better. How many people outside Japan started from scratch and looked at ways to design new types of audio amps circuitry?
If you want to be thought of other than a complete idiot perhaps you should be more specific instead of generalising, what audio circuits? what do you do that is different? Name me an amp or designer where he has started from scratch with mosfets and what he has produced. Amp design is like a game of chess, it has to have rules or you can't play. Each of the chessmen (components) has usage rules, otherwise the device wont play or self destructs in a cloud of smoke, good fun but it plays no music. Individuality comes in how you play the game in regards to sequence and pattern. Same with amp design. Anyway in reality all this about output stage configuration is small beer compared with other parameters like power supply as so succinctly put by anthonyTD in another thread, who is not just some pseudo wanna look big knowledgeless prat.
:lol:
How many people outside Japan started from scratch and looked at ways to design new types of audio amps circuitry?
We did!;)
We did!;)
Just about everyone does, otherwise they are not worth their salt, which is why the statement / question was so stupid. Very few people just ape application notes, though they are a good start point, at least you know *that* works.
It is normally in the early days of a new genus like the Hitachi power mosfets in the early 80's that people use purely the application note but as time goes on new things are seen and done and others build on it, like a pyramid of the possible. It is even fun when things go wrong, especially if you are a secret pyromaniac like me, my early teenage fun in components working for G.W.Smith and Co Radio Ltd in Lisle St (which is now part of London Chinatown, I went for meal in my old shop a couple of months ago) as Saturday boy was finding out which components make the biggest bang when wired across a mains block. :mental: good thing I wear glasses, otherwise I would be my avatar.
But to quote Dr. Bunsen Honeydew "who needs eyes when you have glasses".
How much bias needs a SR402b to sound well ?
The Crescendo resp. Vellemans amp is NOT a "High End"design. Of coarse it's fun to make it, but don't expect something better then an average commercial amp (say Onkyo, Harman Kardon, Bryston etc.).
Not yet mentioned in this thread is that there are newer mosfet's from Hitachi which are a lot faster so bandwidth and slew rate both improve in a design.
Some mentioned the "loudspeaker protection" circuit as offered by Velleman. In that circuit there's a relay contact at the output of the amp. IMHO there's no need for that. We deliver mosfet based amps since 1989 and NEVER heard of any problem (blowing up the loudspeakers).
The real fun for an audio amateur is to construct something (an amp) that outperforms most commercial products at a reasonable price. If someone is interested I could publish the circuit of our famous A-18 on these pages. In that amp there even are NO source resistors so the fet's are directly connected with the loudspeaker.
John
Hi John,
Good to see you back. Where have you been old chap, and what's happened to your avatar? :)
Marco.
Hi Marco
I've been very busy. We had quite some orders for class-D and class-A amps. The most remarkable (and enthousiastic one) came from Hong Kong. The guy mentioned our class-D being cheap considering the audio quality.
Also I developed a new phono preamp and now I'm busy on a complete stereo system which will be called the D-303. The "303" being a reminder for some! It's a (3-channel) stereo amp with an extra (filtered) bass channel and it comes with two smallish tube loudspeakers, each with a single full range driver, and a passive subwoofer. So there are no passive filters and all loudspeakers are directly controlled by the power amps.
I uploaded a picture of myself again let's have a look.
Let's enjoy the music!
John
Excellent, John. Good to see you're busy :smoking:
Do pop in whenever you can because I always enjoy your contributions.
Regards,
Marco.
Filterlab
08-05-2008, 09:31
It's been a while John but I'm glad you're still about. Nice that you've been busy with orders too. :)
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