(AK) classA HA/Preamplifier.

[XTRProf]

Nov 24, 2010 3:00:01 GMT @sandyk said:

Nov 24, 2010 2:36:54 GMT XTRProf said:

For those without the PSU (I mean not the V regulators) + transformer, I think it will be good to recommend the PSU kit + transformer as well. Also, are we going to mass order the closely matched LS transistors here or what? Another thing is how can people have closely matched hfe 450-550 for transistors T4 BC558B,
T5 BC557B, T6, T8 BC547, T7 BC549C, T9 BC337 and
T10 BC327 when they don't have the equipment to do so. I believe many people will want the best for their kits as well.


Thanks.

Chong
The thread has all along recommended the Jaycar KC-5418 PSU kits, which are complete except for the need in this case for 2,200uF 35V electros instead of those supplied.
Due to the weight of the 18-0-18VAC 30VA toroidal transformers, it is recommended that they be obtained locally.
Although most members who will be building the amplifier will not have access to dedicated Transistor Testers, many DVMs do have a transistor test facility.
I feel sure that someone like Will perhaps , may be able to help out with suitable small signal devices for Q4 etc. if asked nicely when the Group Buy dual transistors are sent out, as the quantities needed will be quite small, and some of us buy them in bulk to get very good quantity pricing.
Alex

Oh, the Jaycar PSU for the SCHA. Good! So at least for those who don't know how to build one can carry on with this project.

Agreed with your reasoning for the transformer but perhaps we should put a link to one supplier as an example of what the transformer specs is all about.

I think we should buy in bulk the closely matched LS and everyone into this project will have a good pricing for them. I'm sure many will buy more than the required as backup. So can we combine?

Yes, I'm asking nicely and thank all very much.

[Deleted]

I think we should buy in bulk the closely matched LS and everyone into this project will have a good pricing for them.

Chong
That is what I said in the previous reply. There will be a GB of the LS313 and LS352
Alex

[XTRProf]

Nov 24, 2010 3:23:20 GMT @sandyk said:

I think we should buy in bulk the closely matched LS and everyone into this project will have a good pricing for them.

Chong
That is what I said in the previous reply. There will be a GB of the LS313 and LS352
Alex

Good, now all system go for all ..........

[Will]

Hi Chong,

GB for the LS transistors

www.diyaudio.com/forums/group-buys/177402-linear-systems-ls302-ls313-ls352.html

PM'd you a link for a suitable, local transformer.

As mentioned previously in the thread and bom

Is there interest in set of matched transistors and diodes ? Economy of scale would work well I feel, and can include test transistors as mentioned for start up. I won't do matched LS devices, due to their cost.

[Deleted]

Nov 24, 2010 8:29:59 GMT Will said:

Hi Chong,

GB for the LS transistors

www.diyaudio.com/forums/group-buys/177402-linear-systems-ls302-ls313-ls352.html

As mentioned previously in the thread and bom

Is there interest in set of matched transistors and diodes ? Economy of scale would work well I feel, and can include test transistors as mentioned for start up. I won't do matched LS devices, due to their cost.

Will
The correct type of 3.3V Zener is critical here.
Alex

[Will]

This one, I recall?

uk.farnell.com/fairchild-semiconductor/bzx55-c3v3/diode-zener-3-3v-500mw/dp/9844562

[Deleted]

Nov 24, 2010 9:08:50 GMT Will said:

This one, I recall?

uk.farnell.com/fairchild-semiconductor/bzx55-c3v3/diode-zener-3-3v-500mw/dp/9844562



Yes.

[Will]

Just realised I'd not posted the circuit I'm working from, which is of course taken from the original on page 4 of this thread.

[XTRProf]

Nov 24, 2010 8:29:59 GMT Will said:

Hi Chong,

GB for the LS transistors

www.diyaudio.com/forums/group-buys/177402-linear-systems-ls302-ls313-ls352.html

PM'd you a link for a suitable, local transformer.

As mentioned previously in the thread and bom

Is there interest in set of matched transistors and diodes ? Economy of scale would work well I feel, and can include test transistors as mentioned for start up. I won't do matched LS devices, due to their cost.

Sorry, can't stop the feeling ........ Oh, you are WOODENHEAD at DIYAudio?

Yes, there is a general trend for matched transistors and diodes. So how much is each matched LS devices? Also, is the higher hfe LS302 a better device than the LS313?

I think I will log in to DIYAudio.

Thanks.

[Spirit]

Nov 24, 2010 9:40:03 GMT XTRProf said:

Oh, you are WOODENHEAD at DIYAudio?

Have a look at his 'friends' list (on diyA). I'm sure you'll figure it out

[Deleted]

is the higher hfe LS302 a better device than the LS313?

Chong
Forget that one.
The collector current rating is too low.
Alex

[XTRProf]

Nov 24, 2010 10:01:09 GMT @sandyk said:

is the higher hfe LS302 a better device than the LS313?

Chong
Forget that one.
The collector current rating is too low.
Alex

Thanks. Drop then. As I have not looked at the specs, I thought that's supposed to be an overall uprated version of the LS313.

[XTRProf]

Nov 24, 2010 9:58:01 GMT Spirit said:

Nov 24, 2010 9:40:03 GMT XTRProf said:

Oh, you are WOODENHEAD at DIYAudio?

Have a look at his 'friends' list (on diyA). I'm sure you'll figure it out

Thanks. Having a look now to have more of the cheeky fun feeling.

[Deleted]

Is there interest in set of matched transistors and diodes ? Economy of scale would work well I feel, and can include test transistors as mentioned for start up. I won't do matched LS devices, due to their cost.

Will,

anything that helps is welcome. Just a few more parts to go and we'll have a kit

[Will]

Chris,

Should be no problem, I'll check through what I've got and see how I can help you and Chong out.

I've got no 1930/5171 toshibas left, and have been looking around.

I found this, and was wondering if they look kosher?

cgi.ebay.co.uk/4-X-MATCHED-TOSHIBA-2SA1930-2SC5171-AUDIO-TRANSISTOR-/150511696303?pt=LH_DefaultDomain_0&hash=item230b3239af#ht_921wt_1025

Tubeshunter supplies matched sets of the toshibas, one set would be perfect for the output pairs.

I don't know though

[Will]

Everyone who is having PCBs, please check your email, thanks.

[XTRProf]

Yeah, what's the wattage requirement for the resistors? Also, the voltage requirement for capacitors?

D1 1N5819, what diode is it? Is it Schottky?

Casing what you guys are using?




Thanks.

[Deleted]

Nov 25, 2010 5:14:17 GMT XTRProf said:

Yeah, what's the wattage requirement for the resistors? Also, the voltage requirement for capacitors?

D1 1N5819, what diode is it? Is it Schottky?

Casing what you guys are using?




Thanks.

Chong
I am using normal Jaycar .6W 1% MF resistors which come in packs of 8. The 1N5819 is a low forward voltage Schottky diode.
Mine is in a 1U rack case as per the photo.



Uploaded with ImageShack.us

[FritzS]

Nov 25, 2010 5:48:45 GMT @sandyk said:

Chong
I am using normal Jaycar .6W 1% MF resistors which come in packs of 8. The 1N5819 is a low forward voltage Schottky diode.
Mine is in a 1U rack case as per the photo.



Uploaded with ImageShack.us

Alex,
thanks for posting again, a picture says more than 1000 words

What think you about using »audiophile« resistors (pure copper leads, ....)?

I think about to change from screw terminals to soldering binding-posts.

[Deleted]

What think you about using »audiophile« resistors (pure copper leads, ....)?

Friedrich
Like Frans , I have grave doubts about the advantages of Audiophile type resistors, except PERHAPS at the input and feedback resistors. Things like that are usually the province of those trying to squeeze a little more detail out of a very mediocre design that needs all the assistance it can get , even if the added treble is artificial !
Having said that, Jaycar's replacement stocks of ordinary 1% MF resistor packs now feature copper leads.
Alex

[Deleted]

The differences with the well known 'Dale' resistors in the HF/RF part can only be measured well above 20GHz (that's 20,000,000 kHz !)
Standard MF 1% resistors (like Alex says) are already extremely good.

If you feel using 'audiograde' resistors will help in the sound ... they definitely will.

[FritzS]

Jaycar's replacement stocks of ordinary 1% MF resistor packs now feature copper leads.

I will see (or you can help me) which manufacture / type are behind - I order my parts mostly from RS, Distrelec, Farnell, ... they are locally in Austria too.

I know about this resitors
Dale RN55D (First Watt B1 Buffer Preamplifier, Nelson Pass)
Dale RN60D
Caddock MK-132
TT-Welwyn MFR4 (Solo, Graham Slee)
TT-Welwyn MRS25
Welwyn RC55C 0,25W 0,5% (WNA MKII HA, David White)
Holco H4
MFR4 TT-Welwyn
MRS25 Vishay

Distrelec sells
MBB/SMA0207 0.4W +-0.1%
www.distrelec.at:443/ishop/Datasheets/niMBx-SMA-prec_e.pdf

I think 0.4W are for the most OK, or?

[Deleted]

Nov 25, 2010 7:21:35 GMT FritzS said:

Jaycar's replacement stocks of ordinary 1% MF resistor packs now feature copper leads.

I will see (or you can help me) which manufacture / type are behind - I order my parts mostly from RS, Distrelec, Farnell, ... they are locally in Austria too.

Freidrich
Just order .5 or .6W 1% MF resistors. Order extra ones for matching purposes in critical areas such as the emitters of the current mirror and differential pairs, (or use closer tolerance resistors there) as well as extras for the feedback network resistors so that gain can be more closely matched between channels.
As Frans says, if you think that will make it sound better, then it will!
Alex

P.S.
When soldering in closely matched resistors, ensure that the soldering iron is at the most ideal temperature, because resistor values DO change when soldering for longer than absolutely necessary.

[Will]

The resistor model I've used for the PCB layout is based on the Vishay MRS25, 0.6W body. (207/10mm pitch, full details in the link in the BOM)

I chose these as they are a good GP resistor that are about £2 for 50. They also normally come at the same value (little variance from the stated value) in the same strip.

I've also placed 3.8mm pitch holes on the input, feedback and output resistor, if you fancy trying them naked foil jobs.

Any normal 1% 0.5/0.6 metal film resistor should be good to go. Just ensure that they are not too big, otherwise you'll end up tomb-stoning.

[Deleted]

Is there interest in set of matched transistors and diodes ? Economy of scale would work well I feel, and can include test transistors as mentioned for start up. I won't do matched LS devices, due to their cost.

good idea Will, i would be up for that

take care

oh yes before i forget ;D Last orders for this round of the great Jaycar extravaganza

i have orders from Mr Fritzs and Will so any one else interested let me know by Friday 26th Nov. i will be up for another order after Xmas so anyone having problems ordering from Jaycar will have another chance.