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Post by videoguy on May 20, 2015 3:02:26 GMT
For complete information see the (AK) Class A HA/Preamp thread; go to page 83 & read all of the posts on that page. The ordering information for the printed circuit boards is listed there. The amp. takes 1ea. pcb's; one for each channel.
A word of warning; this is not an inexpensive build & the builder needs to have prior experience with a couple of DIY builds.
rockgrotto.proboards.com/thread/3977/ak-classa-ha-preamplifier?page=83 |
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FritzS
Been here a while! 
Sound of Blue Danube
Sound of Blue Danube
Posts: 1,364
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Post by FritzS on May 22, 2015 12:53:36 GMT
For complete information see the (AK) Class A HA/Preamp thread; go to page 83 & read all of the posts on that page. The ordering information for the printed circuit boards is listed there. The amp. takes 1ea. pcb's; one for each channel. A word of warning; this is not an inexpensive build & the builder needs to have prior experience with a couple of DIY builds. I hope for a summarization of all all modifications of all electronic devices (power supply, JLH, amp self).  To read all mods hints on all of the 83 pages are a hard work  |
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Post by videoguy on May 23, 2015 0:39:13 GMT
Agreed Fritz: Am working on completing the JLH & Power supply part list. The part list for the AKHA is nearly complete & will be posted on completion. My wife & I are in the midst of rearranging the house to suit the realtors.
Hoping for a quick sale to be able to move to a condo in Clearwater, Fl.
Want Sandy K. to edit all of the updates, before posting them.
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Post by videoguy on May 24, 2015 0:31:43 GMT
OK: This will be the new AKHA build thread; as the original is too long & complicated.
Those signed up for new AKHA circuit boards; these will be 1.6 mm thick (standard) & have 2 OZ. copper traces.
Sandy K. 1 set
Pink Floyd 1 set
C.J. 1 set
Bill W. 2 sets
Freddy Pippsqueak 1 set
Malrdaw 1 set
Arjen 1 set Plus interest in the proposed group buy LS 313 & LS 352
Pingu 2 set
Jeff C. 1 set
We have already reached a total quantity of 26 boards. The quote I received from the manufacturer for 16 boards was $148.00 USD delivered to my address in Fla. Each board at that quantity would be $9.25ea. in USD.
If we get to 20 or above I expect the price per board to be a little lower.
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Deleted
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Post by Deleted on May 24, 2015 0:42:49 GMT
OK: This will be the new AKHA build thread; as the original is too long & complicated. Those signed up for new AKHA circuit boards; these will be 1.6 mm thick (standard) & have 2 OZ. copper traces. Sandy K. 1 set Pink Floyd 1 set C.J. 1 set Bill W. 2 sets Freddy Pippsqueak 1 set Malrdaw 1 set Arjen 1 set Plus interest in the proposed group buy LS 313 & LS 352 Hi Bill Mike cancelled in a previous post. What is the expected price for a set of LS313 and LS352 ? Somewhere around $26 perhaps ?
Kind Regards Alex
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Post by PinkFloyd on May 24, 2015 8:24:52 GMT
OK: This will be the new AKHA build thread; as the original is too long & complicated. Those signed up for new AKHA circuit boards; these will be 1.6 mm thick (standard) & have 2 OZ. copper traces. Sandy K. 1 set Pink Floyd 1 set C.J. 1 set Bill W. 2 sets Freddy Pippsqueak 1 set Malrdaw 1 set Arjen 1 set Plus interest in the proposed group buy LS 313 & LS 352 Hi Bill Mike cancelled in a previous post. What is the expected price for a set of LS313 and LS352 ? Somewhere around $26 perhaps ?
Kind Regards Alex
Hi Alex, I'm back in again!! Mike. |
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Post by videoguy on May 24, 2015 19:10:48 GMT
The pricing from the dealer comes to $24.20 USD, per 2 pairs; 2 of ea. transistor for two boards; plus $0.25 USD, to cover shipping to my location. The only additional cost would be postage from myself to the end user.
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jc
Fully Modded
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Post by jc on May 24, 2015 21:33:20 GMT
This seems to have gathered some momentum, excellent! I think we have as many builders as the first time around?
I would also be interested in a pair of the "LS" devices.
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Deleted
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Post by Deleted on May 24, 2015 22:14:13 GMT
This seems to have gathered some momentum, excellent! I think we have as many builders as the first time around? I would also be interested in a pair of the "LS" devices. Me too. 2 pairs for spares.(there are 2 PCBs) Beats trying to glue together matching BC560C and MPSA18!! |
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jc
Fully Modded
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Post by jc on May 25, 2015 12:16:59 GMT
Aye, my wording was a tad vague! A pair for each board is more correcter-er-est...
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Post by videoguy on May 28, 2015 14:40:59 GMT
As of this morning we have 13 sets of boards spoken for; that comes to a total of 26 boards. We will be closing this order Sunday night; any orders after that will need to wait until there are a minimum of 8 boards total for a second order. Those participating are: Freddy Pippsqueak 2, Maldraw 2, Sandy K. 2, Mike 2, C.J. 2, Radius 2, Pingu 4, Bill W. 4,Arjen 2, Jeff C. 2, emtech 2.
This leaves the present total at 26 BOARDS.
NOTE: The LS 352 & LS 313 matched transistors are the key to this circuit working as designed. I will open another list for these devices.
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jc
Fully Modded
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Post by jc on May 28, 2015 15:29:21 GMT
As of this morning we have ten sets of boards spoken for; that comes to a total of 20 boards. We will be closing this order Sunday night; any orders after that will need to wait until there are a minimum of 8 boards total for a second order. Those participating are: Freddy Pippsqueak 2, Maldraw 2, Sandy K. 2, Mike 2, C.J. 2, Radius 2, Pingu 4, Bill W. 4. This leaves the present total at 20 BOARDS. NOTE: The LS 352 & LS 313 matched transistors are the key to this circuit working as designed. I will open another list for these devices. Have we lost Arjen and ematech? Good point on the LS's, I have one set in-da-box but if I intend to finish the second power amp I should keep a set for that. Soooo, Me x1 set. |
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Post by videoguy on May 31, 2015 18:25:58 GMT
No CJ: They are on the list. It is Monday June 1st. The group buy for the AKHA PCB Boards is now closed!
The following members will be receiving boards:
Ematech 2 boards
Jeff C. 2 boards
Sandy K. 2 boards
PinkFloyd 2 boards
Freddy Pippsqueak 2 boards
Maldraw 2 boards
Arjen 2 boards
CJ 2 boards
Pingu 4 boards
Bill Wilson 4 boards
Total Order: 28 boards
June 6, 2015: as of this date the order for pcb's have been ordered & paid for; only those on the list will receive boards. Now everyone needs to decide how many dual transistors they will need & get on the list that follows. NOTE: each set of two boards will need a total of 4 transistors (2ea. LIS 313 & 2ea. LIS352}
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Post by videoguy on Jun 4, 2015 17:39:55 GMT
As soon as the orders are complete for the transistors, they will be ordered.
Those already on the list are: CJ 1 pair (4 transistors)
Arjen 2 pair (8 transistors)
Jeff C 1 pair (4 transistors)
Pingu 2 pair (8 transistors)
Sandy K. 2 pair (8 transistors)
Bill W. 1 pair (4 transistors)
pINKFLOYD 1 PAIR (4 TRANSISTORS)
IF YOU ARE NOT ON THIS LIST YOU WILL NOT RECEIVE ANY TRANSISTORS!
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Post by PinkFloyd on Jun 4, 2015 20:37:49 GMT
As soon as the orders are complete for the transistors, they will be ordered. Those already on the list are: CJ 1 pair (4 transistors) Arjen 2 pair (8 transistors) Jeff C 1 pair (4 transistors) Pingu 2 pair (8 transistors) Sandy K. 2 pair (8 transistors) Bill W. 1 pair (4 transistors) IF YOU ARE NOT ON THIS LIST YOU WILL NOT RECEIVE ANY TRANSISTORS! Oh go on Bill....... put me down for a pair (4 transistors) I may as well get them from you. Mike. |
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Post by PinkFloyd on Jun 4, 2015 20:50:22 GMT
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Deleted
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Post by Deleted on Jun 10, 2015 2:20:32 GMT
Bill has a very annoying health problem at the moment which makes it difficult for him to compose a post.
Bill has asked me to request that everyone on both the transistor & board list send him their email & home address via a P.M. so he can send them the amount owed, once he knows what it is, and of course forward the PCBs and Transistors.
" Thank You.
Best Regsrds
Biil W." |
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Post by PinkFloyd on Jun 11, 2015 21:08:51 GMT
Doing that right now mate  |
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pingu
Been here a while!
Reallising what has been taken on with the GB
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Post by pingu on Jun 11, 2015 23:07:54 GMT
Bill has a very annoying health problem at the moment which makes it difficult for him to compose a post.
Bill has asked me to request that everyone on both the transistor & board list send him their email & home address via a P.M. so he can send them the amount owed, once he knows what it is, and of course forward the PCBs and Transistors.
" Thank You.
Best Regsrds
Biil W." Done Alex Thanks |
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Post by jeffc on Jun 12, 2015 11:44:33 GMT
Hi Alex,
OK to have my PCBs and transistors sent via you? If so I'll pay Bill direct for the parts minus postage and fix you up later for this including additional postage to Bris.
cheers.. jeffc
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Deleted
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Post by Deleted on Jun 12, 2015 12:09:32 GMT
Hi Jeff No problems. I will have some bits and pieces to send to you anyway.
Kind Regards Alex
P.S. Another listening session again on Wednesday, when the modified SC DAC and Class A Preamp will be again compared against the expensive Bricasti M1 DAC , and an almost $50K Gryphon Preamp through big Pass 100W Class A monoblocks. Last time the others were only a smidgin better, but since then a few domed top Suntan electros have been replaced, and the cap across the 1M in the Preamp's Offset Corrector increased from 2n2 to 4n7.It does sound even better through my speakers now. |
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Deleted
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Post by Deleted on Jul 15, 2015 1:46:01 GMT
The photo of the Preamplifier version shows the most recent JLH PCBs designed by Greg Erskine, as well as the presently discussed new PSU PCB design from Greg. (The new PSU PCBs should come in black as well)
Note that due to layout considerations, the LHS Channel has nuch longer power supply leads than the RHS channel.
That is why there are 2 green leads going from the JLH PSU for this channel to it's earth terminals.
Note also the much heavier gauge white lead used to supply -20V to the LHS PCB. Yes, they do result in a further improvement in SQ.
I also have on order a couple of very low noise LT1115 I.C.s which will be tried in place of the existing OPA134 in the Offset Corrector section of the PCBs. Changing originally from TL071 to the lower noise OPA134 did result in an improvement.
www.ebay.com.au/itm/180973861640
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Deleted
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Post by Deleted on Jul 16, 2015 10:48:50 GMT
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Post by Deleted on Jul 16, 2015 11:04:27 GMT
In the above PSU schematic, if only the + and - adjustable outputs are required, VReg. 3 and 4, and associated components are not installed. R1 (330 ohms) is not installed either. The PCB will accept either through hole, or Surface Mount diodes in the bridge rectifier section. The inexpensive ES1D very low capacitance, and low Forward Voltage Surface Mount diodes are recommended at this location. Panasonic FC 2,200uF 35V or Elna Gold 2,200uF 35V are recommended for the main filter capacitors, but normal 100uF 35V types at the voltage regulator outputs. (not low ESR types) With the later trimpot version, R3 and R4 are replaced by 2Kohm multi-turn trimpots.
With the HA/Preamp, a high quality 50Kohm stepped attenuator is recommended for use as a volume control. The Output resistor value is chosen to suit the main headphones used,(it can be as low as 10 ohms with low impedance headphones if required) or 100 ohms when used as a Preamplifier. With headphones such as the AKG K701 and many others, 120 ohms is the preferred value.
Due to the height of the Panasonic and Elna 2,200uF 35V capacitors, you will need to mount the PSU PCBs using very short spacers to avoid them fouling the top cover if you use a 1U rack case. 2 x 3mm nuts will give adequate clearance if used as spacers.
The external PSU case uses 2 x 20VA (or higher) 18-0-18 transformers . A non fused I.E.C. mains socket should be used in conjunction with a separate M305 fuse holder for each of the 2 channels. A 0.5A fuse should be fitted in each. The IN side of each fuse holder is connected together, and to the Active tag of the I.E.C. mains socket .The OUT side of each fuse should go to each side of a DPDT switch, then to each transformer. The neutral wires of each transformer Primary winding are connected together at the Neutral tag of the I.E.C. mains socket. If toroidal transformers are used, they may be mounted on a piece of aluminium or copper clad PCB, with the metal, or copper side of the PCB connected securely to Earth at the I.E.C. mains socket.
Alex
P.S. Please let me know of any posted errors or other suggestions . |
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Post by jeffc on Jul 16, 2015 11:46:06 GMT
Hi Alex,
These various schematics get a little confusing between the 15W poweramp and the preamp/HA. For example, the 15W has matched 200R for the LS352 compared to 150R in other preamp schematics. Just in kitting up, I've bought some 0.1% 150R. Are these now superseded by 200R in the preamp or OK to use the 150R? Also what's the latest diode type recommended for connection to the 3K3/BC547? SF12/ES1D? Just getting keen :-). I have the PS PCBs built using the suggested ES1Ds, Vishay 038RSU normal 63V/100uf used. Working on fitting the 18-0-18 transformers into their box now.
cheers.. jeffc
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