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COMPONENTS

Peerless Speakers

Peerless drivers for the AKSONICS are available from the following US distributors:

Madisound Speaker Components; 608-831-3433;
info@madisound.com; www.madisound.com

Parts Express; 800-338-0531; www.partsxpress.com

Speaker City USA; 818-846-9921; www.speakercity.com

Locations for other international distributors can be found at
Danish Sound Technology

HARDWARE

Wire Monkey

This company is a boutique manufacturer of enclosures for tube equipment. Wire Monkey products are exceptional, and the premium product, the 'Box Seat', appears suitable for the GK-1. (The GK-1 preamplifier will require flying leads from the pcb to the tubes, but care has demonstrated hum problems can be minimised using this approach.) The Box Seat is priced at $US139.95 plus S&H.

The solid walnut front panel on the Box Seat is hand sanded and finished with four coats of Varathane® Satin Diamond™ wood finish. This chassis comes fully assembled with gold tube sockets, IEC power socket, 16AWG 10 foot power cord and 3AG fuse holder. Also Included is the black aluminum wrinkle powder coated front panel so you can interchange if you like. A GK-1 built by Dale Herman of Harvard MA has been built using this box and looks sensational!

 

Allied Electronics

This company have various aluminium chassis, and the rack-mount selections seen at Page 66 of their on-line catalogue appear most suitable; either the Rak-Mount Chassis series or the Valu/Line Series. While a 2RU (2 Rack Units = 3.5" high) type will accommodate the AKSA, an experienced standard of constructional technique is required to do so. A 3RU ( = 5.25" high) unit gives a lot more freedom of layout and positioning, and greater constructional flexibility. So, for example, from the Rak-Mount Chassis line-up, one might typically select;

Stock No. Quantity Description Cost
       
736-4212 1 3RU chassis $54.10
736-4242 1 internal chassis $18.38
736-4360 2 handle $10.40 per pair
736-1426 2 ventilated top/bottom $66.20 the pair
       
    Total $149.08 plus shipping etc.
 
From the Value/Line Series;

Stock No. Quantity Description Cost
       
736Q4159 1 3RU case w/o handles $121.65 plus shipping etc.
or
Stock No. Quantity Description Cost
       
736Q4453 1 3RU case with handles $162.60 plus shipping etc.
 
Allied's contact details are;
ALLIED ELECTRONICS INC.
7410 Pebble Drive
Fort Worth, TX 76118
Tel 817-595-3500
Fax 817-595-854

 

Newark Electronics

Newark carry a substantial range of case/enclosure hardware products, although we have yet to evaluate these from their extensive catalogue.
Newark's contact details are;
NEWARK ELECTRONICS
4801 N. Ravenswood Avenue
Chicago, IL 60640
Tel 773-784-5100
Fax 773-907-5211

Mouser Electronics

Mouser lists the BUD rack mount "Value/Line Series" 3RU rack mount case in their catalogue;
 
Stock No. Quantity Description Cost
       
563-HC14103 1 3RU case with handles $162.60 plus shipping etc.
 
Mouser's contact details are;
MOUSER ELECTRONICS
2401 Hwy 287 North
Mansfield, TX 76063
Tel (800) 346-6873 or (800) 34-MOUSER
Fax 817-483-6899

Digi-Key

This old favorite is another well recommended and major supplier of suitable cases/enclosures and hardware.  Pages 555~560 of their catalogue detail the various project cases that they have available.
Digi-Key's contact details are;
DIGI-KEY CORP.
701 Brooks Avenue
Thief River Falls, MN 56701
Tel 218-681-6674
Fax 218-681-3380

 

POWER SUPPLIES

Transformers

Avel Lindberg

Avel Lindberg manufactures toroidal power transformers and is represented in the US, the U.K. and in Singapore.
A suitable toroidal transformer is the Avel Lindberg D4040, a 230VA 25-0-25Vac 4.6A component with 8% regulation and diam./height of 120/51mm.  A 5% version is also offered in the model F5040. Two of their 160VA D4032 of 113/45 are also suitable.
The D4040 is suitable for a single, stereo supply, providing the AKSA is not used at very high levels. However, with an average drain of around 70W maximum, the D4040 should deliver better than 4% regulation. We have found that the regulation of the power transformer has a strong influence on the sonic performance, and would suggest that it is better to spend more on the transformer than going overboard with too much reservoir capacitance, which should not exceed 10,000µF per rail per channel and is quite satisfactory with 4,700µF. Too much capacitance will perceptively slow the amplifier; and is therefore not recommended.
Avel P/No. Y236600 is for a 25-0-25Vac 230VA toroidal from their Y23 range is also suitable for application to an AKSA stereo pair power supply. Primaries are 115V + 115V and the units are rated for either 50/60Hz operation and have a a polyester tape finish. Mounting hardware comprises a metal dish, two foam pads, bolt, washer, and nut which are included with each transformer, and the leads are 150mm/6" stranded, PVC insulated.

 

Toroid Corp

Toroid Corp of Maryland is another toroidal transformer manufacturer as is evident from their name, and they also offer suitable products. Toroid Corporation of Maryland have a 24-0-24Vac 180VA toroidal, which is suitable for the AKSA amp. Their number is 617.242 and details are here.
An alternative option is to use their 22-0-22Vac transformer, designated 713.222. This will give you 32-0-32Vdc rails, which is shy by four volts, but sounds fine. This drops power to 44 Watts, this is not detrimental.

A variety of mounting hardware is offered;
* The "Poly-Mount" which replaces the metal washer and two rubber pads. It is shipped as an integral part of the transformer, and is intended to save labour time to mount the transformer and eliminate the handling of separate mounting washers and pads. The Poly-Mount adds slightly to the height of the transformer.
* An L-Bracket for vertical mounting of the transformer.
* An "omega" shaped bracket also intended to facilitate vertical mounting. "The circular steel bracket, open at the top, envelopes the circumference of the transformer which is securely held in place inside the bracket by tightening two screws through the ends at the top. The bottom of the bracket is welded onto a rectangular footplate with screw slots at each end to assure firm mounting onto the chassis".
* The conventional mounting washer and rubber pads.

Plitron

Plitron is a third highly respected toroidal transformer manufacturer.
The best option here is to go for Plitron's standard power series, which is 25-0-25Vac rated, and the number is 057016201.
This is a toroid with the centre filled with potting compound and drilled for a supporting bolt. The one without the potted centre and a metal disc for support is 057016001.
Both these 160VA transformers will give you +/-36Vdc rails and 56 Watts.
"All standard units are dual 115Vac primary windings. These allow for parallel or series connection to either 115Vac or 230Vac at 60Hz or 50Hz. Units also include stranded leads and potted and drilled centre for ease of mounting. All units in this series are supplied with a potted centre and an integral neoprene washer base. Alternate mounting: supplied with steel cup disk, two neoprene washers, a bolt, nut and flat washer."
AKSA constructors who have purchased Plitron's have advised us that there typically is quite a wait between ordering and supply; possibly Plitron manufacture after your order is received, rather than holding stock on a shelf. We are advised that the lead time can be six or more weeks, and you should make allowance for this accordingly.

 

Diodes

Ultrafast soft recovery diodes are now included stock in the AKSA kits, and their difficult sourcing is thus no longer an issue for AKSA constructors. However, the following information is offered advisedly.

General Semiconductor's

"UG" series is ultrafast-soft recovery, available at ratings up to 200Vrrm and beyond.
* UG4D 20nS 4.0A 200V (this series ranges to 200V Vrrm, with the suffix "D" = 200V; UG4A, UG4B and UG4C are NOT suitable).
* UG5JT and UG5HT 25nS 5.0A and Vrrm = 500V/600V
* UG8D and UG10D series "D" (or better) suffix (= 200V and above) are suitable.


Newark Electronics carries the General Semiconductor UG4D as Newark stock no. 14C7762 @ US$0.77ea
General Semiconductor's SBYV28-200 is a 3.5A, 200Vrrm, ultrafast, soft recovery rectifier diode, intended originally for high speed switching applications. The 200V Vrrm version is the highest Vrrm version available, so check for this when you're purchasing; there are other versions with lower Vrrm, and these are NOT suitable for your AKSA power supply. The rating for recovery time from an average forward current of 0.5A is 20nS, and junction capacitance is rated at 20pF (at 4.0V 1MHz). The prefix "S" indicates a premium speed version; the General Semiconductor BYV28 series has a slightly slower recovery time at 30nS rather than 20nS.
The SBYV28-200 has similar parameters to the UG10DCT. It delivers a very similar performance, but is rated at lower current and so carries more risk of failure under heavy, 4 Ohm loading. When the 55W AKSA is used with 4 Ohm loads, you should use the UG10DCT/BYQ28E.
General Semiconductor include a most readable and informative discussion on the suitability of their diodes for audio applications as a .pdf hereThe SUF30(G or J suffix, both) Shottkey rectifiers suggested (albeit for valve amplifier applications) in this article are marginally suitable we think, although we ourselves haven't tried them. Ratings are 400Vrrm If = 3.0A (a tad low, the SUF15 is NOT suitable due to If =1.5A), a trr rating of 35nS and a recovery characteristic we can take as eminently acceptable by virtue of the Shottkey nature.
A selector for the appropriate General Semiconductor sales office may be found here. Most of the main North American parts distributors are listed as distributors for their semiconductors;


* Allied Electronics
,
* Newark Electronics,
* Mouser Electronics
* DigiKey


as well as several others at least), but our on-line searches on their sites for the SBVY28-200 and the BYV28 series specifically have yielded few if any hits.  You may have to pursue these specific parts directly by email, fax or phone.


Microsemi's

Microsemi's application note "MicroNote Series 302" covers diode recovery characteristic very well, and isrecommended and interesting reading.

We are not aware of suitable Microsemi rectifier diodes, and certainly have not trialed any. There may well be some candidates though; the 1N6626 look interesting; the speed appears suitable although the recovery characteristic isn't specified, suggesting that it is "snappy" rather than "soft".

Philips Semiconductor

BYV28-200, (-300 and -400) ultrafast-soft recovery diodes are available from Philips Semiconductor. There are higher (500V and 600V) Vrrm rated types in this series, but these are NOT recommended as the If rating is lower (at 3.1A rather than 3.5A). 
While the junction capacitance is rated at around 60pF (at 4.0V 1MHz), somewhat higher than the General Semiconductor SBYV28-200 at 20pF, we can guess that the former is probably a lot easier for you to source for your AKSA power supply than the later, and consequently should not be ignored or overlooked. All in all, Philips, though a creditable manufacturer, are not friendly to the DIYer as their minimum order quantities are very high. We offer their range, in fact, but the time delays and MOQs are have been, well, substantial!

 

Capacitors

Nichicon

Nichicon electrolytics are eminently suitable for use in a power supply for your AKSA and the KMH series is now supplied stock in the kit. The Nichicon K-G Series is a premium part, optimised for high grade audio applications. A directory service for finding sales distributors and representatives etc. for Nichicon products is found by following this link.
In our kitset we now supply three of the four requirements for the power supply to suit the AKSA. While we avoid supplying the transformer, we are able to supply the rectifier diodes, (which are almost made from "unobtainium", even in North America, we understand, and certainly our efforts in Australia have been stonewalled until quite recently), the power supply's own PCB (printed circuit board), and thirdly the capacitors.
There are two Nichicon's which are suitable; the KMH industrial grade 1050C rating, part number is KMH50VNSN4700M25B (22mm diameter, 45mm height, snap fit), the KMH63VNSN4700M30B (30mm diameter, 50mm height, snap fit) and the KW50LGSN4700T (35mm diameter, 80mm height, screw top). All are rated at 2000 hours, 105C and all are industry-standard capacitors, but the KW series is very much more expensive, but quoted only 10 milliOhms ESR at 20kHz, which is pretty impressive.  Our power supply PCB is suitable for the KMH series which have snap on connections and no more than 30mm diameter.  These are the less expensive capacitors and they sound marvellous. The PCB measures 86mm x 61mm and mounts all the rectifiers, the spade connectors and the capacitors;  you have only to hook up the transformer and the rail leads and the job is automatically done.

Mallory

Mallory electrolytics are made by The North American Capacitor Company (NACC), which is headquartered in Indianapolis, Indiana.
"Formerly the Capacitor Division of P.R. Mallory, Inc., the company was purchased in 1990 by a management-led group of investors. Today, NACC continues to manufacture and market Mallory products at its modern manufacturing and warehouse facilities located in Greencastle, Indiana and Glasgow, Kentucky."
The Mallory TKA series is 105degC rated, long life, very low impedance, with values to 4,700uF maximum it appears. Other Mallory ranges would be suitable; the SXR and VPR ranges also feature low impedance and suitable ratings, albeit in radial lead cases.

Rifa

Rifa is originally a Swedish company, but having gone through a sequence of mergers and ownership changes in its long history, is now very much a global operation, called Evox-Rifa, with manufacturing plants all over the world.
Their PEH200 series is a high quality, standard can electrolytic range, and we have tested it for the AKSA power supply.  These are very good capacitors, but a tad 'cold' to our liking at the top end of the audio range.

Elna

Elna offer considerble technical explanation of the technology of their Cerafine electrolytic capacitor range, on their website, concluding that;
"the addition of ceramic particles produces sound reproduction that cannot be achieved with conventional electrolytic capacitors for audio."
Despite this our own opinion is not in favour of Cerafines in the AKSA power supply application at least. We think they sound under-rated in the bass, although the midrange and top end are marvellous.  Our judgment is also based on the cost;  these are very expensive components.

Vishay 's

Vishay's website suggests that the Sprague arm of Vishay now only produces tantalum cap's. We understand however that the Vishay/Sprague "Powerlytic" 36DX series is available from Allied Electronics (1-800-433-5700) and Newark Electronics and we think this brand and range quite suitable for AKSA amplifier power supplies.