(AK) classA HA/Preamplifier.

[mrarroyo]

I have not bothered reading this long thread, so what is the purpose of this new board? Thanks.

[Deleted]

Jan 19, 2011 23:14:14 GMT mrarroyo said:

I have not bothered reading this long thread, so what is the purpose of this new board? Thanks.

Hi Miguel
Will designed the new PCB, with a little input from Jon as well in the area of the different pinout of the dual transistors,
to incorporate modifications made to the original PCB design.
It also now has onboard, the originally separate offset corrector PCB.
Will's idea was to make the HA construction more user friendly for less experienced members.
Will deservers a huge vote of thanks for all his time and efforts.
Regards
Alex

[jeffc]

Will deservers a huge vote of thanks for all his time and efforts.

I'll second that Alex !!!!!!!! and as I haven't checked in for a while now, a formal hat's off on those great lookin' PCBs Will.

Still waiting for those Audiowind PSU PCBs to arrive after their epic journey from HK > Austria > HK > Australia. You wouldn't think a missed 'al' could be that important.

cheers.. jeffc

[mrarroyo]

So the outcome is an amp/pre amp? Thanks.

[FritzS]

a short sidestep to resistors ....

whats the difference between the Vishay MRS16, MRS25 (Mouser) and the Vishay MBA/SMA 0204, MBB/SMA 0207 (Distrelec) series?

Which have copper leads? Which are the better choice for HiFi High Audio?

Why ... Mouser dont have all values, so I must buy some from Distrelec too.

Are Nichicon caps good for the PSU?

PS: There are a lot of informations ... which resistors I must change on the Jaycar PSU to get 20VDC?

[FritzS]

Jan 21, 2011 9:48:25 GMT FritzS said:

a short sidestep to resistors ....

whats the difference between the Vishay MRS16, MRS25 (Mouser) and the Vishay MBA/SMA 0204, MBB/SMA 0207 (Distrelec) series?

Which have copper leads? Which are the better choice for HiFi High Audio?

I wrote to rush

Here the answer from Vishay:

Dear Sir,

Technically both series are exactly the same i.e. MRS16, MRS25 is same as MBA/SMA 0204, MBB/SMA 0207.
Both have Cu lead with 100% Sn coating.

You can select from MBA/SMA 0204 or MBB/SMA 0207 as we would like to promote this series .

[XTRProf]

Jan 21, 2011 9:48:25 GMT FritzS said:

a short sidestep to resistors ....

whats the difference between the Vishay MRS16, MRS25 (Mouser) and the Vishay MBA/SMA 0204, MBB/SMA 0207 (Distrelec) series?

Which have copper leads? Which are the better choice for HiFi High Audio?

Why ... Mouser dont have all values, so I must buy some from Distrelec too.

Are Nichicon caps good for the PSU?

PS: There are a lot of informations ... which resistors I must change on the Jaycar PSU to get 20VDC?

Hi Fritz,

If I remember clearly, the MRS25 is the 0.6W in a 1/4W body. The MRS16 will be lower wattage. I think 1/4W version. We need the > 1/2W version. All are copper leads.

There are only 4 resistors that act as a voltage divider for the Vregs on the Jaycar kit. 2 are same value and so are the other 2. I suggest you keep the 2 100R (if they are matched) and substitute the 2 1.1K resistors for around 1.6K resistors to start with. That should bring you to about + side of 20VDC. Best you have 2 or 5K trim pots there for fine tuning. Don't need to be exactly 20 VDC. Only matched +/- DC outputs will do.

Hope this helps.

[Deleted]

I suggest you keep the 2 100R (if they are matched) and substitute the 2 1.1K resistors for around 1.6K resistors to start with.

[Deleted]

Hi MiguelWill designed the new PCB, with a little input from Jon as well in the area of the different pinout of the dual transistors, to incorporate modifications made to the original PCB design. It also now has onboard, the originally separate offset corrector PCB.Will's idea was to make the HA construction more user friendly for less experienced members.Will deservers a huge vote of thanks for all his time and efforts.RegardsAlex

I couldn't agree more Alex, Will's help to me and many others has been invaluable and the boards I've had (and those to come!) have been superb.

Syd

[Will]

Thanks for the kind words here and by email, Guys, it really is appreciated.

Apart from the odd wall falling down, and a missing parcel it's been pretty painless!

All parcels have been posted, apart from a couple waiting on parts, and are winging their ways to you.

The best way of re-paying me is to build them up sharpish, and use them to listen to some lovely music, which is what it's all about!

[Deleted]

Fine tuning the regulator output voltages.
IF the regulator output reference voltage was exactly 1.25V, and the 100 ohm and 1.6K resistors were exactly the marked value, just reducing the value of the 100 ohm resistor to 99 ohms will give you an extra 200mV or thereabouts to help counter the effect of the voltage drop through the JLH CL section..
This could be achieved simply by soldering a 10K resistor across the 100 ohms under the PCB . Get the general idea ?
Alex

[XTRProf]

Jan 21, 2011 10:55:08 GMT @sandyk said:

I suggest you keep the 2 100R (if they are matched) and substitute the 2 1.1K resistors for around 1.6K resistors to start with.

Great! The more technically accurate method ..............

[Deleted]

Hi Will

My Boards and components arrived this morning so great news.

to say that the quality is superb does not do justice to them ''fantastic'' work Will

many thanks for all of the hard work you put into them, they are going to be a pleasure to use.

THANKS!

just a quick question

i did notice way back in this thread that Alex suggested using NON low ESR caps in the build. I'm curious to know the reasoning behind this and where they should be used.

take care

[Deleted]

Hi Shaun
I only use low ESR electros in the JLH. Even then, it MAY be an advantage to use one of each type in parallel for the 2,200/4,700uF
That will depend also on your system balance.
What I have presently should sound identical to what we will end up with.
Regards
Alex


www.diyaudio.com/forums/solid-state/142166-new-amplifier-uld-extreme-43.html posts 429 and 430

[Deleted]

Hi Alex

thanks for the reply

i have been wondering on what caps to use for the signal board.

so far i have used Panasonic fc for the PSU and JLH and was going to use them for the signal board also.

but

i have some general purpose ones on order from Jaycar and will probably end up using those instead. i just need to wait for the order to arrive.

i have been working on the input relays boards for the pre.

I've gone for two of those audiowind ones to allow switching for signal and ground. i did end up removing the reg and powering with a regulated switcher wall wort to allow them to be stacked and squeezed up nice and close to the input RCA's (yes i know but switchers are useful sometimes). I've also wired the two boards to the same switch.

it works so now i just need to get it fitted into the case

pictures to follow

take care



take care

[Will]

Hi Shaun,

Glad you like the PCB's and thanks for letting me know that they've arrived. That's two sets safe and sound so far.

Looking forward to the pictures

[jonclancy]

Hi Will,

Make that 3 sets!!! mine were waiting for me when I got back home this afternoon. And some other stuff as well. A BIG thanks to you for all your efforts!!!

The boards are, well, a work of art, tbh. I have never seen FR4 so thick!! This should be fun!!

Cheers

Jon

[Will]

Hi Jon,

Excellent! Glad they got there ok. They are pretty meaty, aren't they!

[Deleted]

Hi All

DC offset unloaded 16mV
DC offset loaded uV (yup so low my multimeter runs out of resolution)
TP1-2 set to 200uV ish(again so low my multimeter runs out of thinking power)
100ma set

well done Alex and Will

stunt transistors in

NO HUM, a smidgen of hiss

even on the crap forlorn hope headphones it sounds great

i think it's time for the nice transistors

so halfway there just the pre to do now

come on you lot

[Will]

Jan 27, 2011 12:58:49 GMT @shaun said:

Hi All

DC offset unloaded 16mV
DC offset loaded uV (yup so low my multimeter runs out of resolution)
TP1-200 uV (again so low my multimeter runs out of thinking power)
100ma set

well done Alex and Will

stunt transistors in

NO HUM, a smidgen of hiss

even on the crap forlorn hope headphones it sounds great

i think it's time for the nice transistors

so halfway there just the pre to do now

come on you lot

You beauty!

So it works then? (my layout, not your assembly skills )

Have you tried the balancing yet (just to try it out)

DMM to mV range, a probe at tp1 and 2, and adjust trimpot for 0v.

Top stuff, Shaun!



Oh, and we want pictures!!
rockgrotto.proboards.com/index.cgi?board=general&action=display&thread=4876

[Will]

Sorry Shaun, was the TP1 measurement (0.2mV) the result for the balancing?

Good luck with putting the LS devices in, I nearly broke my eyes doing that!

Check your email before you do

[Will]

[glow=red,2,300]Ensuring the 1n5819 is installed correctly.[/glow]

Nestling warmly between T3 and T2 is one of the things that makes this amp the superb amp it is. The LTP thermal balancing mod, and it's associated diode. This diode is mounted standing upright. To ensure that it's mounted in the correct orientation, there is a '-' symbol on the pcb, indicating which way around it should go.

Hopefully the picture attached should help, but if you are unsure, please do ask

Attachments:

[Deleted]

Hi Will,

For super novices like myself, is this what you mean?

Chris

edited 'cos of unknown alt. meaning of slang, good grief, never realised that

Thanks for the alert Shaun.

Attachments:

[Will]

Perfect Chris, much better than my effort!

[Deleted]

Sorry Shaun, was the TP1 measurement (0.2mV) the result for the balancing?

yes W ill it was as close as i could get it. then i noticed that my meter measured that when it was not connected so maybe even better than that.

take care