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Old 4th June 2002, 07:48 PM   #16
mlloyd1 is online now mlloyd1  United States
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I think it was Radio Electronics (RIP) some years ago that featured a power MOSFET based amp that used a switching power supply. I know the guy that did the power supply design. The amp designer's name escapes me at the moment, but he sells kits of the projects. Look in the thread on distortion analysis and you'll see his name with pointers to his web site.
OK, OK I just remembered - reinhard metz
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Old 4th June 2002, 08:08 PM   #17
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Quote:
Originally posted by Aud_Mot
BeanZ,


...In the context of this forum, linear supplies are easier to understand, design, build, test, and repair. They have the reputaion of "sounding" better.
Also this is the forum for sound, not practicality. That explains all the people building high power single ended solid state amps that are 12- 25% efficient.

All of the above points are accurate. In fact, my high power dual mono amplifier uses a huge 1500VA linear unregulated power supply, so I do implement them as well. I am just fishing for people who want to try something new. Good answer Aud_Mot!

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Old 4th June 2002, 08:20 PM   #18
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Scorpion,

Since we are slightly off topic of the thread lets address the original neophyte. It is recommended to choose an amplifier design which you want to implement. There are lots of projects which you can execute yourself and range in all classes of amplification. Not knowing your background a good book to look at is :High Power Audio Amplifier Construction Manual, by Randy Slone and the Audio Power Amplifier Design Handbook, by Douglas Self. These are good references however not absolutely necessary. The next expensive investment after the power supply and the enclosure is going to be the heatsinks. The size of the heatsinks are dependent on the class of amplifier you build. Class-A amplifiers require huge heatsinks, AB require large heatisinks, Class-T requires tiny heatisinks. I assume that quality throughout the entire range is desired so I have eliminated class-D. Class-T is very difficult and quite different to implement. Heatsinks can be found at surplus shops for cheap. Buying them new are extremely expensive. Once class is decided the next investment will be the output transistors. No matter what class you choose or what kind of transistor output )MOSFET or Bipolar, this is the next expensive investment. Complementary pairs are quite often chosen for best quality. Bipolar pairs are MJ15003 /4 pair or the MJE21193/4 pair. Though with most of the available projects online it will tell you the best parts for the application. What are your requirements?

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Old 5th June 2002, 12:31 AM   #19
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Mr Feedback, thanks for that article by Jim Hagerman, very interesting reading indeed. Makes a change from my typical “that looks about right” approach.

Aud_mot, actually Linn use switching supplies on their Klimax amps, regarded as very good amps indeed. Yes switching supplies can be difficult to design and repair, but they have many advantages over a conventional linear supply.

I felt tiroth’s suggestion to build a smaller amp as a first project was a very worthwhile suggestion.

Cheers,

Pete
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Old 5th June 2002, 04:14 PM   #20
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Hi all,

thank to all for you very kind answers. As it is only my second post on this site, I don't know (yet) how to respond personnaly to each and everyone of you therefore my reply will cover many of your comments.



TO TIROTH:

I am not sufficiently skilled or have a great knowledge in DIY stuff. That is why I am on this site to ask pros like you guies.

Money was spent this way: 600$ US (1000$ CAN) for the Plitron LONO transformers (2 at 1KVa ), another 600$ US (1000$ CAN) for the boards, wiring and components and 300$ US for the all-around 5/16 '' thick chassis, machining and anodizing.

I am not looking for exotic stuff but just trying to have tips to maximise my efforts with the components I have. Of course, I will be tweaking and tunning the amp for a year or two (and might change some components along the way). Anyway, it's all about system synergy and more than everything the final product will have to be pleasant to my ears.


TO JOCKO HOMO AND HARRY HALLER:

Of course, good parts does not always mean good sound (altough it might help). To me it's all about synergy. Synergy between the components in the amp and between the amp and the rest of my system and more importantly between the final sound and my level of pleasure !!!

I bought lot of stuff from a surplus store. For exemple, Mallory CGS capacitors cost me a total of 70$ CAN (45$ US) for 4 70V 40 000uf and 8 75V 20 000uF !!!

TO HPOTTER AND AUD_MOT:

I was talking canadian dollars, sorry for the mistake !! . Here are some important details that all of you should know :

This circuits I will use are built here in Montreal by a friend that has over 30 years of experience in the audio field. He personnaly knows the owners (see inventors) of companies like Sim Audio, Classé, Totem (years ago) and especially Tenor Audio (recently)and has sometimes helped or commented on their project (some of the Tenor Audio stuff are now on the market). This guy has been building amps for more than a decade. I listenned to some of them, they are incredibly musical and...they sound true.

The circuits I will use are his. I don't have a great knowledge of DIY and that's why he'll help/supevised me. Here are some details about the boards:

Bipolar boards with 4 outputs per channel mounted directly on board, working in class AB, running at +- 64V, Teflon OFC 4 onces (like in big Levinson) board with a dielectric of +- 2, trace fully balanced, impedance fully balanced, heatsink and output transistors mounted directly on board so it is fully operationnal even without a chassis, each electrolytic can is bypassed by a prolypolen cap (Solen for now) directly on board. These boards will be my starting point but any comments on how to improve them are truly welcomed. I might try to scan them and provide a picture.

As far as LEDs are concern, I am wondering why companies that build big and expensive amps (like Gryphon, Burmesteer for exemple) seperate the LEDs from the audio path if they're are no differences in the sound or why display can sometimes be turned off. It might just be a marketing strategy. I'm inclined to think that LEDs might make a difference in sound, even slightly but again (as someone once told me) some golden ears can hear flies fart....;-)


TO HPOTTER, HARRY HALLER AND ALL:

It seems like there is no consensus on wether IXYS bridges are the way to go (at least it seems to be the opinion of BeanZ). Comments on the sound of Digikey diodes and/or IXYS bridges would be appreciated.

After reading your posts I have no doubt that 2 bridges per channel are the way to go. That's exactly what I am going to do. I'll just have to select the proper one.

I will use 4.5% silver AND 3% solder (? brand ? it will be provided by my friend). Both are better sounding than anything eslse I have tried this far. Now wich will go where is another story. I'll have to experiment. In my experience Cardas solder gives weight and ambiance but at the detriment of pace and rythm. It muffled a little too much the sound for my taste. The 3% solder I am using has IMHO the qualities of the Cardas but offer a more natural and transparent presentation of the stage . The 4.5% solder (while lacking in body and warmth) is clean, fast, transparent, vivid and has superbe detail retrivals and do the pace and rythm thing extremely well. It sounds better to me than any 4% I've tried.

In my experience putting the solder in that order give the best results: 4.5-3-3-4.5 (in my speaker`s crossover).

Again, thank to all for your kind answers

Best regards to all,

Sincerly,
Marc-André Rodrigue
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Old 5th June 2002, 04:40 PM   #21
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Quote:
Originally posted by Scorpion

It seems like there is no consensus on wether IXYS bridges are the way to go (at least it seems to be the opinion of BeanZ). Comments on the sound of Digikey diodes and/or IXYS bridges would be appreciated.

After reading your posts I have no doubt that 2 bridges per channel are the way to go. That's exactly what I am going to do. I'll just have to select the proper one.
Marc-André Rodrigue
When you use two bridges and two windings (for plus and minus supply) you won't load the transformer so much. If you use only one bridge you half wave rectify the current in each winding and this creates more losses in the transformer but you get half in rectifier losses. You win also a volt or two. I gather the losses thing is not important in your case....

Correction: My statement is true (or more true) if the load is unsymmetrical, not likely in an amp....) It's very true if you connect the windings in parallel. You can then get losses due to not equal voltage...

My recommendation is that it's no harm to use two bridges if you can afford it and/or have the room them.

My bridge type recommendation is a slow ordinary type with 4 caps. Use 10-100nF film or ceramic, good HF performance. 100 nF polyester 63V or 100V is quite alright.

You can also use a faster bridge but beware of the emission and decouple it carefully.
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Old 5th June 2002, 08:01 PM   #22
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Default We'll cross that bridge

"My bridge type recommendation is a slow ordinary type with 4 caps. Use 10-100nF film or ceramic, good HF performance. 100 nF polyester 63V or 100V is quite alright.

You can also use a faster bridge but beware of the emission and decouple it carefully"

Use RC snubbers instead of just caps.

High speed soft recovery diodes generate MUCH LESS RFI noise. That is the point of using them.

Two bridges are worth using to keep the charging current out of the finite impedances of the power supply ground wiring.

The load on a power amplifier is asymmetric during large bass transients and music signals are also asymmetric.

I suggest all interested do a search since this has been discussed in some detail in the forum.

H.H.
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Old 5th June 2002, 08:46 PM   #23
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Default Alloys Alliance

IMO lead and silver sonically do not go well together.
96%tin/4%silver is quite ok.
60% lead/38%tin/2%copper is quite decent, and tins/solders very well.


Regards, Eric.
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Old 8th August 2002, 09:47 AM   #24
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I know this is an old thread, but I was surprised that nobody mentioned the Chord Electronics amps (UK, nothing to do with with Chord interconnects). All of their amps have used SMPS for at least a decade, possibly two. These are very highly regarded-and expensive-units.

Check out this site: www.chordelectronics.co.uk

They look gorgeous too!
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Old 8th August 2002, 12:26 PM   #25
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Hi Persig

The Chords are indeed an exception. They don't have an SMPS for cost reasons but because they are convinced that their power supply is better than a conventional supply.
But there is much effort put into the development and construction of their SMPS compared to a PC grade powersupply, i.e. it is definitely NOT cheaper than a conventional power supply.

I once heard a real beefy Chord amp connected to a newer Tannoy Speaker (I think the name was "Dimension 12"). And I can confirm the combination sounded clean and pleasing. And when cranked up it sounded still that clean and unstrained but quite brutal !

Chord amplifiers are the ones that are recommended for use with the larger Dynaudio Acoustics Studio Monitors.

Even though I once developped an SMPS, I would strongly recommend generously designed conventional powersupplies for DIY.

Regards

Charles
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Old 8th August 2002, 12:57 PM   #26
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Quote:
...In the context of this forum, linear supplies are easier to understand, design, build, test, and repair. They have the reputaion of "sounding" better.
Agreed, it's the route of choice for pretty much all of us. PSU for my A75 is to be PI filter, traditional but sound (sic!).

A question for Scorpion:
Quote:
I bought lot of stuff from a surplus store. For exemple, Mallory CGS capacitors cost me a total of 70$ CAN (45$ US) for 4 70V 40 000uf and 8 75V 20 000uF !!!
. Where is this surplus store please? A website would be most helpful, but an address will help.

Thanks
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Old 8th August 2002, 04:29 PM   #27
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Default IXYS

The IXYS high speed soft recovery diodes are excellent. I have also used RC snubber on hign speed diodes and seen reduction of high frequency noise. The only reason I can think of to use regular slow diode bridges is to save money. I have changed to high speed soft recovery diodes on dozens of audio circuits with great results.

http://www.gensemi.com/appnotespdf/quik108.pdf

http://www.ixys.com/

http://131.109.59.51/images/pdf/Calculatin_%
20Optimum_Snubbers.pdf

http://www.gensemi.com/appnotespdf/quik108.pdf
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Old 22nd January 2004, 11:32 PM   #28
Luke123 is offline Luke123  Canada
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Default Scorpion...

Scorpion

You said :" He personnaly knows the owners (see inventors) of companies like Sim Audio, Classé, Totem (years ago) and especially Tenor Audio (recently)and has sometimes helped or commented on their project (some of the Tenor Audio stuff are now on the market)."

What is the name of this guy?

Luke123
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Old 12th January 2008, 02:38 AM   #29
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Hi all,

I know it was years ago but should you guies be interested in how my dual-mono power amp looks, here are a few pictures. It weights 140 lbs !!!

This is the MKII version as I modified a few things along the way.

Should you have any questions, please don't hesitate.

Regards

Marc-André alias ''Scorpion''
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Old 12th January 2008, 02:40 AM   #30
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another pic
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