(AK) classA HA/Preamplifier.

[pingu]

May 27, 2015 9:54:54 GMT @sandyk said:

[quote source="/post/138734/thread" timestamp="1432720088" author="@pin

Martin

Hi Martin

 Don't forget that you need 2 PSU PCBs for this dual mono HA/Preamp

I have emailed Bill re your PCBs

Regards

Alex

[/quote]

Thanks Sandyk yes just ordered one to see if they were ok. I'll get another one when this one comes.
Please put me down for two pairs of the semi conductors LS devises if there is a GB on them

Martin

[pingu]

Oops better make that eight in total (enough for the four boards)
Martin

[Deleted]

May 29, 2015 20:45:32 GMT pingu said:

May 27, 2015 9:54:54 GMT @sandyk said:

[quote source="/post/138734/thread" timestamp="1432720088" author="@pin

Martin

Hi Martin

 Don't forget that you need 2 PSU PCBs for this dual mono HA/Preamp

I have emailed Bill re your PCBs

Regards

Alex

Thanks Sandyk yes just ordered one to see if they were ok. I'll get another one when this one comes.
Please put me down for two pairs of the semi conductors LS devises if there is a GB on them

Martin

[/quote][/p]

Hi Martin

 The LIS devices are essential for the best performance. I  would suggest that all interested send Bill a PM with your requirements to make sure that he can send out the PCBs and the LIS transistors in the same package. Bill is getting the best possible price for these devices from a major U.S. distributor.

Incidentally, with the JLH PCBs, I don't recommend the use of Panasonic FC 100uF in that location. Use normal 100uF electros there as the very low impedance of the FC tends to harden sound a little. The Panasonic FC 2,200uF 35V are great in the PSU PCB though.

Kind Regards

Alex

[jeffc]

Hi Alex/Chris/Bill,

AWOL for far too long....... Just happened to look in at RGF on a whim and was interested to see 'another' AK Class A amp adventure about to start. I have quite a few parts leftovers from the previous builds, so too good an opportunity to let slip by for an AK pre- to match the AK power amp.

so
2 x Amplifier PCBs
2 x LS transistor pairs
JLHs?? - Alex, if you have any of Greg's older dual JLHs, I have one of these stuffed but idle, so 1 to match would help. Otherwise I'll be happy to go into a GB for some more RG singles or Greg's updated duals, whatever gets decided.

cheers.. jeffc

[Deleted]

May 29, 2015 23:48:50 GMT jeffc said:

Hi Alex/Chris/Bill,

AWOL for far too long....... Just happened to look in at RGF on a whim and was interested to see 'another' AK Class A amp adventure about to start. I have quite a few parts leftovers from the previous builds, so too good an opportunity to let slip by for an AK pre- to match the AK power amp.

so
2 x Amplifier PCBs
2 x LS transistor pairs
JLHs?? - Alex, if you have any of Greg's older dual JLHs, I have one of these stuffed but idle, so 1 to match would help. Otherwise I'll be happy to go into a GB for some more RG singles or Greg's updated duals, whatever gets decided.

cheers.. jeffc

Hi Jeff

I will shove a couple of Greg's latest JLH PCBs in the mail next time I am near a P.O.

 (You may need to remind me though, as these days I don't get to a P.O. too often due mainly to mobility reasons ,

so I have run out of stamps.) I think that I may have 1 only of the previous non black underside JLH PCBs too for matching purposes.

I will send you all the updated info via Filemail a little later. This build will be with a normal thickness PCB with 2oz copper instead of the original 3mm thick with 1oz. copper .

 Whatever you do, don't use Suntan electros if Jaycar is still selling them, after I gave them a blast via the editor of Silicon Chip magazine about their domed tops and leakage from using that pirated electro formula that stuffed so many PC motherboards a few years ago.

 If you have any Suntans in JLHs or PSU PCBs (2,200uF or 4,700uF) please check them for domed tops.

They do however work well and sound good before they prematurely fail.

 I hope to obtain a few more updated PSU PCBs from Greg, so if I do I will send you a couple of them too.

Otherwise, the original Jaycar PSU PCBs could be used with a couple of extra 1mm holes drilled to accept the fatter Panasonic FC 2,200uF 35V electros.

Kind Regards

Alex

P.S.

Is your email address still the same, as you should have received RG emails about this provided that you didn't opt out of receiving them.

[jeffc]

Gee whizz Alex...

That's way too may generous offers.... thank you..

Re the Suntan low-ESR JLH caps... yep.. most of mine have popped their lids long ago and have had me worried enough to pull and bin them. I really like the Nippon KZEs here. It's interesting how these can alter the sound flavour. The really-low ESR Panasonic FR are OK too although a little too much in your face used alone, and mixing of the 2 I've found to be a good compromise.

Re +/- PSU PCBs, I have a couple of Will's design unused so was planning to use these, nice and compact and I have heat sinks to suit, so I'm OK for these. Should be OK to durry-rig those fast SMD diodes. On these, is the 50V rev voltage 'A' type OK..? cheaper ATM at element 14 or RSC, although I think I have some 'D' types hiding somewhere too.

JLHs, although singles are nice for close connection, some time back I nabbed a couple of nice aluminium scientific instrument cases discarded at work. These by serendipity are going to be close to perfect for this project, but width will suite dual JLHs positioned close behind the amp PCBs better.. so duals are it, and the one spare of Greg's that I have stuffed is green... I've got home-etched ones and singles stuffed too but I'm a bit OCD with neatness and symmetry :-), as you know..

And yes.. a normal thickness PCB will be just wonderful.. I would still be hiding in the shadows otherwise..

cheers.. jeffc

[pingu]

Hi Alex,
Thanks I have mailed Bill my details and request for bits
Regards
Martin

[malrdaw]

Please add 2 pairs of the trannys and 2 of the JLH PSRR "ripple eater" boards for me also.

Regards Malcolm

[Deleted]

May 30, 2015 6:59:13 GMT jeffc said:

Gee whizz Alex...

That's way too may generous offers.... thank you..

Re the Suntan low-ESR JLH caps... yep.. most of mine have popped their lids long ago and have had me worried enough to pull and bin them. I really like the Nippon KZEs here. It's interesting how these can alter the sound flavour. The really-low ESR Panasonic FR are OK too although a little too much in your face used alone, and mixing of the 2 I've found to be a good compromise.

Re +/- PSU PCBs, I have a couple of Will's design unused so was planning to use these, nice and compact and I have heat sinks to suit, so I'm OK for these. Should be OK to durry-rig those fast SMD diodes. On these, is the 50V rev voltage 'A' type OK..? cheaper ATM at element 14 or RSC, although I think I have some 'D' types hiding somewhere too.

JLHs, although singles are nice for close connection, some time back I nabbed a couple of nice aluminium scientific instrument cases discarded at work. These by serendipity are going to be close to perfect for this project, but width will suite dual JLHs positioned close behind the amp PCBs better.. so duals are it, and the one spare of Greg's that I have stuffed is green... I've got home-etched ones and singles stuffed too but I'm a bit OCD with neatness and symmetry :-), as you know..

And yes.. a normal thickness PCB will be just wonderful.. I would still be hiding in the shadows otherwise..

cheers.. jeffc

Hi Jeff

 I have had to mix and compromise too with the big electros in the JLH. It's amazing how much they can affect the ultimate sound quality. The combo that works well in the digital area of the SC DAC doesn't sound quite right in the Preamp or 15W.You need one low ESR and one normal ESR in parallel. It's even harder with the DAC that doesn't use the Current Limiter but uses 4,700uFs which are often either too tall or too fat.

I would use the ES1D if you can find them. I got mine off ebay originally. Through hole types SF11 or SF12 would also do but not quite as good there.

Kind Regards

Alex 

[videoguy]

Hi All: Finally back after 16 days. I have received two of the ceramic input selector switches used by Sandy K. & others. I have decided to go another route & not use them. They cost $6.95 USD for both switches. Just want to recover the purchase price,as they are now excess in my inventory.

[Deleted]

Jun 15, 2015 4:53:09 GMT videoguy said:

Hi All: Finally back after 16 days. I have received two of the ceramic input selector switches used by Sandy K. & others. I have decided to go another route & not use them. They cost $6.95 USD for both switches. Just want to recover the purchase price,as they are now excess in my inventory.

Hi Bill

If you intend going with relay switching, remember that most as seen cheaply on ebay will reduce channel separation. 

Also, they do not switch the earth side of the inputs, which will degrade S/N if one of the inputs is used with a device powered by SMPS, even if it is on standby.

Note also, that channel separation is maintained in the selector switch by having the hot side of one channel opposite the earth side of the other channel on the other wafer.

Regards

Alex

[videoguy]

Hi Sandy K.
I will not be using the cheap stuff on flea bay. Going to lay out my own board & switch both hot & gnd. There will also be a 6.8k terminating resistor across every unused input. Will be using good Omron dpdt relays, for switching.

[Deleted]

Jun 18, 2015 4:12:22 GMT videoguy said:

Hi Sandy K.
I will not be using the cheap stuff on flea bay. Going to lay out my own board & switch both hot & gnd. There will also be a 6.8k terminating resistor across every unused input. Will be using good Omron dpdt relays, for switching.

Hi Bill

That's good to hear as we had another listening session yesterday where a Laptop using USB Out with an external JLH PSU into an expensive and very good Bricasti DAC  went into a >Au.$40K Gryphon Pandora,  then a pair of Pass 100W Class A monoblocks into big (tall) Revel Speakers.

After that we tried the new server made by RG member david2vk into the same chain, and it clearly outperformed the laptop. It was quite a small server with an i7 processor inside  , using JLHs in the external PSU, as well as inside the server (IIRC)  which used only an 80VA toroidal for 2A max. 

I wanted a reference to see how the Server, which sounded very good, compared with a hardware configuration, so we tried a PSU modified PWT (Perfect Wave Transport) into my heavily modified S.C. DAC via supposedly inferior Coax SPDIF , and the Class A Preamp which have both been constructed by quite a few members.

This combination was by far the best on the day, and I was asked how much they both cost to make.

The instrumental track "Sumiyaki Coffee" from the Jheena Lodwick -Feelings Vol.2 HDCD" sounded sensational.

I.M.E drums simply have more impact through a fully D.C. coupled Preamp !

Regards

Alex 

[videoguy]

Hi All: Hoping the AKHA PCB's will be arriving state side in the next two weeks. I am sure we all are set & ready to build as soon as they arrive.

[videoguy]

I have sent everyone who is due AKHA boards & transistors a personal message. I need your mail to address so I can get the correct postage for your shipment as soon as the parts arrive & send a bill.

bill W.

[Deleted]

Jun 29, 2015 0:25:38 GMT videoguy said:

I have sent everyone who is due AKHA boards & transistors a personal message. I need your mail to address so I can get the correct postage for your shipment as soon as the parts arrive & send a bill.

bill W.

Hi Bill

email sent.

Kind Regards

Alex

[jc]

Decided to finally whip my first pre (the thick board type) out of its slot and sort the SF12 diodes by changing them to ES1Ds and then rebalance. While I was there I noticed I hadn't done the paranoid-android procedure of passing pins through all of the vias and soldering them so this is now done. While under inspection I was also surprised to find several dry joints, one had even came adrift once gently probed!

Hoping to sort a new front panel soon (existing is a cheap plastic affair) and slot the pre back in its home.

(the integrated I'm trying to finish is still only boards but I have decided to buy in a chassis, sooner rather than later, to get that puppy finished too.)

[Deleted]

Hi Chris
I am surprised that you found a couple of dry joints.
I have never bothered with pins or offcuts through vias, but perhaps when assembling, it may be a good idea to drop a tiny amount of flux from a Flux Pen into each via, then solder from the bottom ?

Jeff has still to report back with his progress too.

Kind Regards
Alex

[avtrouvaille]

Hi,

Back in 2015/16 I have participated in the GB with transistorset for the AKHA Class A headphone amplifier.
Now I finally have time to built, but the schematic (and possibly build instructions?) are not in my archive.
In this thread the schematic should be on page 4. Do I have to join Photobucket to see the images?
Can someone please get me started?


Arjen
email: [e-mail]

[pingu]

Sept 16, 2019 21:09:22 GMT avtrouvaille said:

Hi,

Back in 2015/16 I have participated in the GB with transistorset for the AKHA Class A headphone amplifier.
Now I finally have time to built, but the schematic (and possibly build instructions?) are not in my archive.
In this thread the schematic should be on page 4. Do I have to join Photobucket to see the images?
Can someone please get me started?


Arjen
email: [e-mail]

Hi Arjen
I think they are all gone when Dropbox started to charge for hosting some time ago and the forum moved pix hosting. Pink Floyd will know
Your best bet for help with your amp is video guy on here try a PM to him, he’s been quite helpful to me and posted a few notes about end of life bits
I have a BOM if you need it but no diagram or build notes so when I get to finish mine I’m going to struggle too.

Good luck

Martin