'AK Mods' SC Class A 15W Amplifier

[Deleted]

Jun 4, 2013 23:09:15 GMT drymdrum said:

au.element14.com/on-semiconductor/byw80-200g/diode-rectifier-8a-200v-to-220b/dp/2101175

Hi Alan
I only Googled BYW88- 200 and there was an Element 14 ad for them. I entered the part number and it came back with 2 of the MUR devices.
I got the same morning when I tried again a few minutes ago. I will see what happens when I go directly to my usual element 14 link.
The ON.data sheet for the BYW88-200 doesn't show it as soft recovery though.
Regards
Alex

P.S.
When I go directly to element 14 and enter the part number, it gives 4 results. However, the 3rd and 4th are for MUR820 !

[Deleted]

Some people should be aware that, if you encourage someones silly idea by telling them how good it was, they will do it again...

Twins!

[Deleted]

Hi Chris

A nice pair

Great work

Are they both using the Pioneer honeycomb heat sinks?

I have one of those that I use for testing stripped out of a not working A400.

Just the main event to go

Take care

[Deleted]

Hi All

After discovering that what goes on behind the reg really does matter and checking out a few diodes with interesting results I decided to try one more before settling.

With a heavy nudge from Will I decided to give the Cree SiC schottky diodes a try and was headed in the direction of Cree.

These 8A diodes.

www.cree.com/~/media/Files/Cree/Power/Data%20Sheets/C3D08060A.pdf

So nope not soft recovery diodes.

OK looking at the forward voltage drop for these diodes @ 8A it’s typically 1.6V but drawing much less current with 1A I was hoping for less. The Data sheet indicates 1V @1a which looked OK and would still leave enough over the reg to allow correct operation.

So voltage over the regs with the BYW80-200 was measured at 6.7V with full load.

And

The voltage over the regs was measured at 6.7V again with full load so it looks like Cree’s Data sheet is a little conservative in that respect.

TBH the first thing I thought when I looked them up at Digkey was GULP those are expensive.

So anyhow I ordered some anyway as the SQ I have from Alex’s class A for what I’ve spent on parts is an absolute bargain so well worth pushing the boat out to see just how good it gets.

Well I fitted them to the experimental diode boards and had a listen.

So IMHO. to my ears and in my setup

The first thing I noticed was that they sound really smooth but at the same time detailed and very musical. On further listening it became apparent that the sound stage had become much deeper and more focused with vocals extending well out from instruments. This seemed almost like turning the volume up a few notches.

So to some up in a word

Musical

Worth the cost

Hell yes

For the increase in musicality, focus, sound stage stability and dynamic contrast they are well worth the cost for the benefits that they deliver.

It’s been a fun learning curve for me and nice to have a few ideas altered in the process.


Thanks for the nudge Will.

a truly great sounding diode

and also

I’ve been having a play with this

www.belden.com/techdatas/english/19364.pdf

Its nice stuff if a little on the large side diameter wise so a large entry MK plug is useful or you could just buy a kit from here.

www.ebay.co.uk/itm/AUDIOPHILE-DIY-MAINS-LEAD-SET-FOR-UNDER-20-BUY-NOW-LIMITED-STOCKS-BELDEN-/150963875838?pt=UK_Computing_Sound_Vision_Power_Cables_Connectors&hash=item232625effe

So anyone who may want to experiment with such things whilst not breaking the bank then this could be a good place to start. I’ve had it connecting Alex’s PA power supply box to the mains and now I think that I may try rewiring the PSU internals with also. It may also be good for the umbilical from PSU to AMP box.

I’ll give it a try and let you know.


Take care

[Deleted]

Now stop right there Shaun!

I haven't even finished the standard build yet, I'll be pulling it to bits before first switch on at this rate

BTW, the 2nd psu is using a smaller 'sink. Just about to power that up again after some problems with naff SIL pads caused some pyrotechnics, quite impressive actually

[Deleted]

Hi Chris

Noooooo

Build it as standard first and then get a handle on how it sounds.

Then if you like to experiment a little then that’s OK.

But

Putting the new bits in first deprives you of the chance to learn and find what suits you (sir).

It's not just the having it's also the learning.

I’ve had over a year with Alex’s superb amp so I have a great deal of respect and understanding for what this amp can do.

Build it as standard and get it all working as it should. Then get to know it a little and enjoy.

Remember some of those parts cost a little more than the standard and going up in smoke will be more expensive.

With my builds I’ve always tried to go for the minimum cost first to see what it sounds like and then if I feel the need have a little play with components.

‘’15W only good for background music’’ AND ‘’the more power the better’’ (how many Watts is it guv?)

Yup hard to believe isn't it Chris that people still have those kinds of ideas in 2013.

Nope Quality is everything

You’re in for a real treat Chris with those speakers.

I can’t wait to have your thoughts on the SQ.

Take care

[Deleted]

Jun 11, 2013 17:17:29 GMT @shaun said:

Hi Chris

Noooooo

Build it as standard first and then get a handle on how it sounds.

Then if you like to experiment a little then that’s OK.

Do not worry my friend, I learnt that lesson on the HQ SCDAC. A very bland sounding DAC lifted to beguiling heights, each mod listened to carefully before progressing.

Yes, a great learning experience coupled to a fab final result.

p.s. did you that joker on £bay asking £21 a pop for those Cree diodes

[Deleted]

Hi Shaun
Those diodes do look interesting, but at around $52 a set (Element14) I will be passing on them for now. It would be interesting if someone with a CRO that has much wider bandwidth than my 6MHZ old clunker had a look at this area to see what difference there is in the EMI area especially. That Belden mains cable looks like it would be interesting to try between the PSU and the mains socket if you aren't already using heavy duty mains filters.

Hi Chris
Has the next "Houston, we have lift off" been put on hold ?


Kind Regards
Alex

[Deleted]

Yeah!

A last minute attack of chicken-shitness

I'll bring in my light bulb voltage reducer thingy wotsit and have a controlled blast off with that, one board at a time....

[Deleted]

Jun 11, 2013 21:49:39 GMT @cjarchez said:

Yeah!

A last minute attack of chicken-shitness

I'll bring in my light bulb voltage reducer thingy wotsit and have a controlled blast off with that, one board at a time....

What's the fun in that ? The aluminium cans of reversed electros reach a higher terminal velocity at higher voltage !

[Deleted]

Hi Chris

Yes I did notice that crazy price for those diodes on ebay.

Makes the ones that I have look quite errrr cheap.

Hi Alex

Maybe another GB for the Diodes would make things a little less expensive for anyone interested.

I’ve listened to the Amp all day now and it really has taken a noticeable step forward not so much in the more detail kind of way but in presentation, depth and separation.

Things seem much more real and natural without any of the softness or added warmth Usually associated with such words. Extended top and bottom with a real wallop and ultra tuneful Bass when needed with everything seeming more solid and focused.

A real all around improvement that would be hard to miss even from the most cynical scientist (or maybe not ).

Farnell have an in stock 650V 8A Cree which has pretty much identical specs which could be worth looking at.

For a GB the economics of scale would help the price come down a little. The in stock items would avoid paying the extra £15 we have here for US orders.

I have the Belden hooked up to the mains ATM but not internally or between PSU and Amp which look like another good place to try it out.

It’s good, not too expensive and a good place to start experimenting.

No filters used except an isolation transformer on the Buffalo.

Take care

[Deleted]

A real all around improvement that would be hard to miss even from the most cynical scientist (or maybe not ).

Hi Shaun
Try telling that to "Archimago" and someone we know .
I crossed swords with Archimago in C.A. where he tried to get a lot of members to engage in his stupid MP3 tests.
He is just another E.E. that listens with his test equipment !!!
He even tries to do a demolition job on jPlay ,and attempts to prove that their claims of improved audio playback are BS.


archimago.blogspot.com.au/

[Deleted]

Hi Alex

MP3? Is that a format that needs at least 200W of power (with the go faster stripe on the side) to make it a little better than background music?

Archi who?

That blog was funny

He should think about a stage act with it.

Yup he could call his act ‘’ a trip back to the dark early seventies with Archi’’

Chris

Yeah!

A last minute attack of chicken-shitness

I'll bring in my light bulb voltage reducer thingy wotsit and have a controlled blast off with that, one board at a time....

Check everything at least twice.

Take care

[Deleted]

Hi Shaun
It would appear that the dangling red herring may have distracted from further investigations into another area.
Regards
Alex

[Deleted]

In the 15W Class A using Will's PSU PCBs, has anybody experimented with different values of C1 across the secondary windings ?
Regards
Alex




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[Deleted]

Those diodes do look interesting, but at around $52 a set

That's double to me!

Farnell have an in stock 650V 8A Cree which has pretty much identical specs which could be worth looking at.

If they perform the same that's a good saving.


Someone say MP3? Wash your mouth out! Isn't it that funny format that lets you have a basic listen to music for free so you can decide whether to buy a proper copy or not


Ref. the chart above;

I went for 6n8 for my 22-0-22 160va jobbies. On previous occasions I've chosen nearest "under" value but then experimented with nearest "over" value. I could swear there is just that little something of improvement to my shell-likes.

[Deleted]

Hi Chris

These are the ones that I’m thinking of which look at a glance to be identical to the ones that I have. Just a slightly higher voltage rating.

www.cree.com/~/media/Files/Cree/Power/Data%20Sheets/C3D08065A.pdf

at Farnell

uk.farnell.com/cree/c3d08065a/diode-schottky-8a-650v-to-220/dp/1864929

worth a go?

Take care

[Deleted]

And another place to think on

Mouser UK

uk.mouser.com/Search/ProductDetail.aspx?R=C3D08060Avirtualkey57280000virtualkey941-C3D08060A

At an even better price and for 16 diodes it's free delivery to the UK

Take care

[Deleted]

Jun 12, 2013 22:03:05 GMT @shaun said:

And another place to think on

Mouser UK

uk.mouser.com/Search/ProductDetail.aspx?R=C3D08060Avirtualkey57280000virtualkey941-C3D08060A

At an even better price and for 16 diodes it's free delivery to the UK

Take care

Hi Shaun

I have a sneaking suspicion that the optimum value for C1 may vary with the type of diode used in the bridge rectifier.
Ever since the soundstage billowed and sounded too diffused with the JLH PSU for the X-DAC V3 , causing me to remove it,
I have been wary of the cap across the secondary winding. Presently, I am still using the original 470pF. in my 15W.
It shouldn't be so critical in a PSU for a PA though.


Kind Regards
Alex

[Deleted]

Typical PSU implementation using Will's PSU PCBs.
I have added a photo of a completed version of Will's very nice, and highly useful PSU PCBs.
As it has many possible future uses, perhaps some of those interested in the Preamp GB organised by Marc should consider adding a couple of these to their GB order if Marc agrees ?
With components as shown, they are capable of supplying up to 3A maximum per supply rail.
For use with a 3 wire output cable, instead of 4 wires, a 3mm hole can be drilled at the 0 volts location between the main PSU electrolytic capacitors, and a couple of spade lugs fitted underneath the PCB .If the copper around that area is revealed, by scraping, the locking nut could then be soldered to the PCB.
This will also facilitate a connection to the metal chassis and I.E.C. earth.
Alex



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[Deleted]

It seems an age since I last even looked at getting these amps moving along from just a bunch of boards in a cardboard box!

A little bit of metal work this morning produced the first, rough cut, home for Amp No.1.
Just sizing things up ready for hole drilling...


(excuse crappy photo)

[Deleted]

Hi Chris

the last time I looked you where almost finished

and now you are errr still almost finished.

any news on you build?

my HA/PRE PA is still sounding superb and you are just a few hours away from the same super sound.

no time to stop IMHO.

[Deleted]

A tad embarrassing really Shaun! In nearly three months from that last post I've achieved, erm, the square root of bugger all.
Amp 1 is in exactly the same state, amp 2 not started!
The only ground I have made is nearly sorting the PSU for the active XO. I may soon be contending for the slowest build ever

A few renovations starting soon here too so I'm really not sure when The Enlightenment of Buddha Chris's Amplification is actually going to happen

It WILL happen though!

[Deleted]

Dec 2, 2013 17:05:37 GMT @cjarchez said:

A tad embarrassing really Shaun! In nearly three months from that last post I've achieved, erm, the square root of bugger all.
Amp 1 is in exactly the same state, amp 2 not started!
The only ground I have made is nearly sorting the PSU for the active XO. I may soon be contending for the slowest build ever

A few renovations starting soon here too so I'm really not sure when The Enlightenment of Buddha Chris's Amplification is actually going to happen

It WILL happen though!

haa

I know the feeling

My DIY has slowed to a standstill.

Most of the house is about to be ripped and redesigned so it’s going to become almost UN livable.

But no rush on the amp.

Just remember

I’m watching you sonny.

Take care

[jc]

I've hit a slight case construction problem/dilema.

With the heatsinks I have for the ouput devices I cannot get the devices to line up perfectly on gaps between fins! If I have one lined up the other MUST fall directly under a fin 

Before I go in and attack, are there any bright ideas on how to create sufficient room in a sink-fin to fit a nut on its mounting screw, or t'other way around? Apart from an over-sized hole!

Ta