(AK) classA HA/Preamplifier.

[jonclancy]

Hi Alex,

They are in a separate case. I'm not worried about noise per se - I was looking at LED-referenced supplies for TDA1541A DEM re-clocking (ECDesigns' work). It was one LED calculator that warned that a supply voltage of over 24VDC would cause too much dissipation. I ended up using 4K7 3W resistors. They aren't too big, fit the board reasonably well and get barely warm when on.

Just the stand-offs to go now and I can assemble the PSU, install the JLHRE in the amp box and close the lid and enjoy!!

Then tidy up the workspace - I wouldn't notice is someone had ransacked the place!!

[Deleted]

Mar 20, 2013 9:55:19 GMT jonclancy said:

Hi Alex,

They are in a separate case. I'm not worried about noise per se - I was looking at LED-referenced supplies for TDA1541A DEM re-clocking (ECDesigns' work). It was one LED calculator that warned that a supply voltage of over 24VDC would cause too much dissipation. I ended up using 4K7 3W resistors. They aren't too big, fit the board reasonably well and get barely warm when on.

Just the stand-offs to go now and I can assemble the PSU, install the JLHRE in the amp box and close the lid and enjoy!!

Then tidy up the workspace - I wouldn't notice is someone had ransacked the place!!

Hi Jon
Using ohms law with a 33V supply and a series 4.7K resistor , and 3V dropped across the white LED, (a little over 6mA)
gives a dissipation in the resistor of a little under 200 milliwatts.
As I said previously, a .6W MF resistor would have done nicely, and still only get luke warm.
That LED calculator appears to be in error.
Kind Regards
Alex

[jonclancy]

Alex, it does indeed.

I've just applied Ohm's Law to the figures myself and concur.

That'll leach me to blindly follow the calcs out there.

Still, the boards might or might not take another round of desoldering, so I may just leave them be. The light levels look pretty good to me - too bright could be too much for the effect I'm trying to achieve. That said, the LEDs are only a secondary consideration after the nut-shrouding and mechanical strengthening requirements.

[Deleted]

Hi Jon,
I just love the out and out class of your construction very impressive, makes mine look positively "Rustic".
Can you drop me a link to your perspex supplier as I'm mulling around a few ideas for the face plates for my #2 builds?

It's one-thing to be "Rustic" up here in the "Den" 
but another when you are sending a "SandyK" out into the big world.
After-all you want it to make a visual statement as well as a "Sonic" one.

Regards,

Alan 

[jonclancy]

Hi Alan,

I found these guys:

stores.ebay.co.uk/sheetplasticssuppliers

Their ad mentioned specific sizes, so I rang them and they sent me a PayPal invoice. The plastic was cut EXACLY to my size and was delivered in a timely manner.

In the past I have got acrylic discs made for this project by the Wholesale POS Co. Equally good service.

www.ebay.co.uk/itm/5MM-CIRCLE-DISC-OF-POLAR-OPAL-FROSTED-PERSPEX-ACRYLIC-/170593262351?pt=LH_DefaultDomain_3&hash=item27b8269b0f

You could also see what Trent Plastics could do for you - but I haven't used them yet.

HTH

Jon

[Deleted]

Hi Jon,
thanks the ebay  firm you used looks okay to me I'm sure to get what I want there should I actually decide on an acrylic front, needs a bit more thought first.

Regards,

Alan 

[jonclancy]

Just remember to use a slow speed when machining (drill or whatever). Otherwise the plastic melts!!

Thi s 7-page dociment from Perspex is pretty useful:

www.perspex.co.uk/documents/technical/working-with/Perspex-and-Extruded-Acrylic.pdf

Cheers

Jon

[jonclancy]

I have got the PSU finished.

Photos uploading as we speak. It's taken a while, but I'm pleased with the result.

Just need to reconfigure the amp box for my Ripple Eaters and I'm pretty much complete on this project!

[jonclancy]

Loads of new photos of the final assembly now uploaded to my album.

[Crispy]

Mar 30, 2013 19:02:54 GMT jonclancy said:

Loads of new photos of the final assembly now uploaded to my album.

Bloody hell Jon - that PSU looks ACE

[Deleted]

Mar 30, 2013 17:56:57 GMT jonclancy said:

I have got the PSU finished.

Photos uploading as we speak. It's taken a while, but I'm pleased with the result.

Just need to reconfigure the amp box for my Ripple Eaters and I'm pretty much complete on this project!

Hi Jon
That's a pretty substantial PSU case. I noticed especially the thickness of the base plate.

With the PSU for the HA used with my PC, I elected to save a few dollars by using a black plastic case with front and rear aluminium panels,
That size aluminium panel was on special at the time from Altronics, so I decided to use them, although I could have got away with the supplied ABS panels.
With my preamp though, I have it's 2 x 30VA transformers in the same 2U rack case as the dual winding toroidal for the 15W Class A.
Kind Regards
Alex

[Deleted]

Nice work Jon

just the main case to go

Take care

[Deleted]

Now we see where the Leds and perspex base come into play, that's a nice touch Jon. 
When I feel more like it (temperature rises) I'll experiment with
twin walled perspex front panels and Leds of course.
Regards,
Alan

[Deleted]

As the antithesis to Jons very tidy PSU and case, here's my first in its temporary home...



Fancy a biscuit?





No? Oh, OK then;







The heatsink is total overkill but I had it in-da-box. Anyway, it works! Just need an amp to connect it to....

[Deleted]

P.S.

Where did you, Jon and Shaun, get those tidy but simple cases from for the PSUs?

[Deleted]

Mar 30, 2013 23:35:48 GMT @cjarchez said:

P.S.

Where did you, Jon and Shaun, get those tidy but simple cases from for the PSUs?

What about this for your PSU Chris?  

[Deleted]

Nice Work

A very tidy build and good use of the honeycomb heat sink (pioneer ?)

I’ve had most of my cases from

modu.it/pesantedeng.html

I used the 2U and 3U dissipante for my Class A PA build and various others for the HA/PRE and various DAC builds. For the HA/PRE Transformer Box I just used Maplins cheap Ali project boxes.

A fair price and good service from Modushop with nice looking cases that cover up my bad workmanship well.

Take care

[jonclancy]

Hi Guys,

Thanks for your kind words - I was lucky in that the case, although reasonably priced from Lawrence in HK, was pretty well finished. It is all steel, bar the faceplate, and is only 1mm thick. That's one of the reasons why I went for the Perspex base; the 80VA trafos are quite weighty!!! Why 80VA? As mentioned elsewhere, they were only a quid or tow more expensive than 30VA (or whatever they were) at the time. May as well over-spec and get to use them elsewhere in the future if needs be and just drop in some smaller trafos if they come up on offer. Note that a load of the online suppliers are offering free postage in a price-war at the moment. Nice!!

Chris, your excellent implementation reminds me of the Altoids-box CMoys. I don't know about temporary - I think you should make that permanent! Looks very tidily laid out from where I am viewing!

[Deleted]

Nicely done Chris,

a very well executed build, deserves a choco medal in a gold wrapper.





Regards,

Alan 

[jonclancy]

Here we go:

Powered up with the JLH Ripple Eaters installed (temporarily).



Loads more images uploaded.







Is this finished now? Sadly not. I need to find some longer stand-offs to mess about with the RE placement. I also need to swap the amp boards out as I mod my spare set to Alex's latest spec. Plus, the output resistor could do with being looked at, I feel (R31). Aesthetically, I think increasing the hole size behind the headphone socket to generate a "halo" effect would be worth considering. Not too much work, and details really, but seeing as I spent 20 minutes re-frosting the perspex disc edges today, I think I might as well finish the job!

It's been a bit of a journey to get here, both in terms of hours and £££. But, this is probably the best pre-amp I could ever hope to own - more's the satisfaction that I stuffed it together.

A big thanks to Alex, Will, Greg, SC and a myriad others for making it possible!

[Deleted]

Hi Jon
All you need now is a nice attenuator for the volume control.
Unfortunately, you are now likely to find that some of your source material, and perhaps your CD player needs upgrading to take full advantage.
After hearing how David's Oppo 95 sounded in my system with a Corsair Voyager plugged in, I will never again be happy with my old Oppo 981 SACD/DVD-A player.
Kind Regards
Alex

[Deleted]

Apr 1, 2013 15:41:37 GMT jonclancy said:

Here we go:

Powered up with the JLH Ripple Eaters installed (temporarily).



Loads more images uploaded.







Is this finished now? Sadly not. I need to find some longer stand-offs to mess about with the RE placement. I also need to swap the amp boards out as I mod my spare set to Alex's latest spec. Plus, the output resistor could do with being looked at, I feel (R31). Aesthetically, I think increasing the hole size behind the headphone socket to generate a "halo" effect would be worth considering. Not too much work, and details really, but seeing as I spent 20 minutes re-frosting the perspex disc edges today, I think I might as well finish the job!

It's been a bit of a journey to get here, both in terms of hours and £££. But, this is probably the best pre-amp I could ever hope to own - more's the satisfaction that I stuffed it together.

A big thanks to Alex, Will, Greg, SC and a myriad others for making it possible!

Hi Jon

Superb work and up to your usual high standard.

As that Carpenters song goes

‘’we’ve only just begun’’

Remember we chatted briefly about those Charcroft resistors?

www.hificollective.co.uk/components/car_resistors.html

Well I’m in the process of collecting a bunch of them for the FB/IP/OP locations as curiosity just got the better of me. It’s crazy frog price time again.

How they going to sound? Who knows maybe worse?

Unfortunately only one way to find out.

I think I may try a 47PF polystyrene on the IP also just as an experiment.

So a little light experimenting on the way.

I’ll keep you posted.

take care

[Deleted]

And further to the component experimentation trip I’ve etched I a couple of HA boards with offset correctors with Alex's cap across the FB resistor (my first work with the PCB software). All working well and sounding top banana.

TBH I just could not consider ripping my existing build of Alex's HA/PRE apart every time I wanted to try something so now I have a mule and something to do a direct comparison with.

I’ll post some pictures of the said mule over the next few days.


A super quality piece of kit so good they named it twice.

Take care

[Deleted]

On the 470pf caps well I’ve used them because they worked so well with the SCHA so do so out of habit but I’ve not tried without so who knows.

Hi Shaun
The SCHA used a single transformer though, so you can experiment here to see if they make any noticeable improvement.
I can't see them in a photo of mine though,
I didn't have Will's schematic and 470nF as Martin said didn't sound right.
Regards
Alex

[Deleted]

Hi Alex

Yes point taken on the number of transformers but Will was good enough to leave space for them so I thought why not.

I will try taking them out to hear if that makes a difference though as they are really only in out of habit.

That 470nf cap (should read 470pf) was a typo sorry Martin for any confusion caused. I’ve gone back and edited it but I must take more care when posting component values.

Take care