(AK) Class A HA PCB and parts Group Buy

[Deleted]

Apr 1, 2013 16:43:30 GMT pingu said:

Hi Alex,
I have now copleted 90% of the PSU boards (Will's Dual Reg) that Shaun kindly sent me (thanks again Shuan) but I am about to order the caps for them and I was wondering should I use "audio grade", low ESR types or just whats "in stock" these are the caps C2 to C6.
Also C1 the small 470Nf 100V cap, as I am using fast schotsky doides is it needed?
The PSUs will be used before the ripple eaters in the SC AH projcet and when some PSUs from the GB arrive they will be used to power a +/- 12v Richard Brice HA from an old HFW project.
I have used the SF 14 diodes as no 12's were around ATM and some thin film 0.6wat resists from RS (good pice).
It seems you have the Knowledge so may I pls pick your brains?
Martin

Hi Martin

That’s a really good question re the Tank caps.

In my limited experience with regulated supplies the dominant sound signature of the reg is the regulator device it’s self. I’ve tried swapping tank caps in and out and TBH it has made very little impact on the overall sound.

Hope that makes sense

So I’d agree with Alex on that front with one add on comment.

I do think that using quality (non boutique) tank caps is still a good idea if for no other reason than longevity. Panasonic FM or SA are not too expensive and nice quality/ non low ESR units and not too expensive.

But

I’d not get tooo hung up on that.

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.

Take care

[pingu]

Thanks Alex all clear now.
I couldn't work out from the board how the anode/cathode of D2/D3 were conected if C1 was left out. The pix shows it clearly (my eyes are a bit dim at times). I have bridged the C1 position.
I have all the resist/cap values now thanks
Martin

[pingu]

Thanks Shaun, just read your comments and as I am a bit deaf (as well as dim...lol) often wondered about boutique bits but assumed it was my faulty hearing aids tee hee.
Yes getting some middle of the road long life general purpose caps from local RS for around a quid rather than over £2.00
The project moves on.
Martin

[Deleted]

I have bridged the C1 position.

Hi Martin
Don't do that ! It will put a s/c across the transformer windings.
You can either fit them or leave them out.
I would leave them out initially, then after you are accustomed to how it sounds,then perhaps try fitting them.
Regards
Alex

[pingu]

Don't do that ! It will put a s/c across the transformer windings.

Ooops Thanks Alex I see now. Silly miss reading of the circuit board
I have PM'd you
Thanks again
Martin

[pingu]

Hi Everyone,
Just waiting for the postie to deliver the caps for the PSU Shaun sent me and then it will be complete.
One question about Txs, if I get one of the cheapy 18v 80va txs that Shaun uses can I power two PUS's and two JHL RE's to run a stereo SC HA?
I was just wondering as these Tx's are so over spec'd (but very economical...Sir as the sales assistant says lol) would they be Ok and I could save some space too, or would it be better to use two Tx's?

Martin

PS update Postie just delivered the caps soldering iron heating up
PSU will powered up when Tx's are purchased.
Martin

[Deleted]

Apr 11, 2013 10:29:55 GMT pingu said:

Hi Everyone,
Just waiting for the postie to deliver the caps for the PSU Shaun sent me and then it will be complete.
One question about Txs, if I get one of the cheapy 18v 80va txs that Shaun uses can I power two PUS's and two JHL RE's to run a stereo SC HA?
I was just wondering as these Tx's are so over spec'd (but very economical...Sir as the sales assistant says lol) would they be Ok and I could save some space too, or would it be better to use two Tx's?

Martin

PS update Postie just delivered the caps soldering iron heating up
PSU will powered up when Tx's are purchased.
Martin

Hi Martin

If you want to use one transformer then I’d just use one PSU board and one +&- JLH to power both HA boards but IMHO two transformers in dual mono config is the way to go.

One question on your JLH set up.

Are you planning to use the CL section? Will you be using 2200 or 4700 caps for C4a & b?

From memory the config of the JLH boards may be a little different for the HA/PRE from the way that you have them ATM.

Good luck with the PSU boards

Mmmmm I can smell the flux from here

Take care

[pingu]

Hi Shaun,
Flux what flux? Bakers fluid... tastes much better.
All soldered up now.
The JHL RE has not got the CL in it and the caps are 4700Uf 16v with the 4700Uf 10v in the normal/low ESR as suggested in the previous posts... hope that is OK
Will a single PSU supply enough power for a stereo SC HA BTW?
All coming together now
Martin

[Deleted]

Hi Martin

Ok I think that I know how the confusion may have arisen.

Here is your original question

rockgrotto.proboards.com/thread/8851/ripple-eater-boards-limited-availablilty?page=1#page=4

Unfortunately the JLH needs to be configured slightly differently depending on where it’s used.

For the application that you asked about in the above link Alex is quite right 4700uf no CL.

But the set up that I’m currently using with Alex’s HA/PRE is 2200uf x 2 and CL in place which is what I’d recommend.

Alex had a similar discussion with Chris re the same question here

rockgrotto.proboards.com/thread/7461/ak-mods-class-15w-amplifier?page=46#page=46

So using them as you have them may not be out of the question.

But Alex may have another way so let’s wait and see on that.

Hope that helps

Take care

[jonclancy]

Chaps, briefly:

PSU caps and 3-pin regulators can be picky.

See some excellent guidance at Acoustica. Page 3 refers, but it's all worth a read.

[Deleted]

Apr 11, 2013 16:52:33 GMT jonclancy said:

Chaps, briefly:

PSU caps and 3-pin regulators can be picky.

See some excellent guidance at Acoustica. Page 3 refers, but it's all worth a read.

Hi Jon

good point and especially on their OP's but i think that martin is asking about the JLH caps.

take care

[Deleted]

But Alex may have another way so let’s wait and see on that.

Hope that helps


Read more: rockgrotto.proboards.com/posts/recent#ixzz2QC1zL1b1

Martin
Shaun's replies have covered this pretty well.
Alex

[pingu]

Apr 11, 2013 21:37:58 GMT @sandyk said:

But Alex may have another way so let’s wait and see on that.

Hope that helps


Read more: rockgrotto.proboards.com/posts/recent#ixzz2QC1zL1b1

Martin
Shaun's replies have covered this pretty well.
Alex

Thanks Everyone, (Alex, Shaun, Jon)

I shall reconfigure the REs to use 2200Ufs and a CL for the SC HA and leave the ones on the Brice HA with the 4700Uf no CL as earlier suggested because it uses about 200/250ma @ +/-12v.

I have read the site Jon pointed me to and "think"( ) I have an idea now.
Thanks Jon.
No doubt there will be more probs/questions when the SC Ha build starts.... so pls be gentle with me .
All the Best
Martin

[Deleted]

Hi All

any news on an ETA for the GB.

take care

[gommer]

Hehe, the files for the HA came in only recently-ish. Will and I both seem to be busy.

I'll kick my butt and make the summary of this thread, then start ordering soon. No fixed date promises though.

Cheers, Marc

[Deleted]

Hi Marc

No worries just had my curiosity running away with me.

No rush on my part.

Take care

[asdiasx]

Hello all!!! Unfortunately I'd only did heard about this forum and GB today... Is it possible to join any GB still running?
It's difficult to find some parts here in Brazil...
If somebody have the main parts to sell (input and output transistors, SF12 and CI) its welcome... Paypal preferred


Thanks in advance and best regards!


Adriano Dias

[Deleted]

Hi Adriano

And welcome to RG

The GB is just about ready to get going so I’m sure that we have room for one more.

If you feel like having a read around this fabulous HA/PRE then Will’s set up info post is a great place to start.

It can be found here

rockgrotto.proboards.com/thread/3977?page=40#

Third post down

And if you’d like to look further then this thread is well worth looking at.

rockgrotto.proboards.com/thread/3977?page=40#page=1

It’s long but interesting.

And of course any questions that you have just ask away as quite a few have built this amp and are coming back for seconds.

Take care

[asdiasx]

Thanks Shaun for the welcome!

I'm trying to read everything... at least trying...

So, I plan to build only a 2 ch HA to use with my AK701.

Will follow here..  Count on me in the group for the PCBs and other parts for this building...

Regards,

[Deleted]

Hi Adriano

Quite a few of us here are using Alex’s HA/PRE with K701 and really like the sound.

Have a read through and if you have any questions along the way please feel free to ask.

Many of us here have experience building this lovely amp and will be only too willing to pass on what we know to you.

Looking forward to building with you

great avitar by the way

Take care

[asdiasx]

Thanks again Shaun! I was "googling" for "best headphone amp for k701" and... that's how I arrived here

K701 is known here as "love or hate it" and this is due to the critical role of the amp and source... People states that although it doesn't have a too high impedance, it demands a "strong feeder" to shine and is very commom to see tube amps recommended...

I love tubes' sound (mainly in power amps), but in this case, I'd like to have something with the physical characteristics of ss and this project, by the comments here,  seems to be a high quality solution!

Hope I can enjoy it's sound soon...

Rgds,

[Deleted]

Hi Adriano

Google gets it right

I was a dyed in the wool tube man before I heard Alex’s amp and it broadened my horizons quite a bit.

IMHO Alex’s Class A HA/PRE seems to have a special synergy with the K701 which none of my other HA get anywhere near. It has the drive ability coupled with a balanced but musical sound which goes beyond the Tubes or solid state thing. With this HA and the K701 I get proper bass which I think is one area that the others fall short on.

Good is good whatever the devices used.

I have the original GB1 build which I love and also a self-etched ‘’ mule’’ which I’m using for a little light tweaking so my third build coming up.

It’s going to be fun so stay tuned .

Take care

[Will]

Apr 18, 2013 18:06:47 GMT gommer said:

Hehe, the files for the HA came in only recently-ish. Will and I both seem to be busy.

I'll kick my butt and make the summary of this thread, then start ordering soon. No fixed date promises though.

Cheers, Marc

Last Sunday even! My fault for the delay, but at least it's Marc who got the hassle now!

[Will]

Hi Adriano,

As Shaun says, Welcome aboard!

I own K701's as well and the AKHA is match made in heaven! I posted a few years back at HeadFi stating this, and never had much feedback from there.

[asdiasx]

Thanks Will, good to know all this...
If I have some time, I'll try to do a prototype with local parts only to have a small taste... 

Rgd