Hafler DH-200,220,500,P225,230 Amp upgrade using the DH-220C design , assembled

Description: For Sale, four assembled and tested printed circuit boards, for you to perform final assembly and testNow that we have some extra help, we can offer these as assmebled and tested.Provide a note on purchase what Hafler model you have since the OPS pcb is different.This is for folks who have previous experience in electronics, not suggested for a first timer. This improved design is for upgrading the legendary David Hafler amplifier models, DH-200, DH-220, P225, P230,DH-500. This design by Bob Cordell improves the old design by incorporating additional features to the old amplifier. The new design follows the original full-complementary push-pull topology but improves on it by using a complementary JFET input stage, current mirrors, buffered VAS, O/V drive and rail clamps, VAS buffer to OPS and a DC servo controller. A separate OPS pcb is used, designed for each model, that contains the gate drive resistors, DC filters, Zobel R/C and a bias sensing resistor. It is adaptable to use current production Exicon mosfets in either TO-264(dual die) or TO-247(single die) plastic, since TO-3 can are EOL.When you purchase this set of four assembled boards, at the time of shipping, you are also provided with links to the documents and the Mouser shopping carts as a reference. The design uses all through hole components, except the smt jfets are mounted on a pcb carrier. You will receive,Two populated and tested pcb sets, consisting of 4 boards, for both channels. The AFE (Amplifier Front End) and the OPS (OutPut Stage).Printed documentation, schematics, assembly drawings, Bill of Materials(BOM). Links to the electronic document web pages, including the detailed build guides, schematics, assembly drawings, BOMs, many pictures showing installation steps in detail. Links to the Mouser shopping carts, to order the parts kit, if ever needed.A write up, by the designer, on the theory of operation and performance testing.The DH-220C is designed by Bob Cordell, to replace the original Hafler designs, PC-6 & PC-19, as an improved design.This new design is featured in Bob's latest 2nd edition book release, "Designing Audio Power Amplifiers", available at Amazon. This design was also presented at the Burning Amp Festival (BAF) in 2016. There is a power point slide set available, google search for "The DH-220C Audio Amplifier Design" A youtube video of this design presentation at BAF2016, courtesy of LIS (Linear Integrated Systems)/watch?v=V7-27fDgqco The book is reviewed using this youtube link/watch?v=Q5nO9QZx37w Audioxpress.com magazine article, reviewed By Jan Didden/article/book-review-a-look-inside-bob-cordell-s-designing-audio-power-amplifiers-2nd-edition DIYAudio has threads on DH-200,220,500 modification and builder evaluations. You can also visit the cordellaudio web siteThe features of this new design are many: The design uses all modern day, current production parts which are readily available. Precision thin film resistors are specified in many positions. High grade capacitors are used. A double sided FR4 pcb is specified with LPI solder-mask, silk-screen legends for easy component installation and location.The AFE IPS (InPut Stage) features full complementary dual jfet's, using LIS LSK489 & LSJ689 devices. The jfets are in a cascode configuration having current mirror loads to ensure excellent IPS differential balance. The jfet IPS allows for a very high input impedance at 200K, so there is minimal loading on the pre-amp.The full complementary IPS design allows for a push-pull two transistor (2T) VAS (Voltage Amplifier gain Stage). A buffer stage is used for VAS isolation and to drive to the Mosfets.A DC servo-control circuit is used, so no AC feedback electrolytic capacitor (ecap) is required, nor are there any DC offset adjustments necessary. The DC offset is always within +/- 10mV of zero, assuring no DC drift is possible. A TI OPA2134 jfet opamp device is used for hi-performance in the DC servo circuit.A high wattage low impedance feedback network is used for low noise and resistor distortion.The OPS (OutPut Stage) pcb design uses local bypassing of the power supply voltage rails. 470 uF electrolytic capacitors (ecaps) help to resolve the class-AB half-wave-rectified currents local to the output stage, especially at high frequencies. They reduce the amount of those currents flowing in the power supply leads back to the main amplifier reservoir capacitors. Local Wima polypropylene film caps are used for high frequency filtering.Inclusion of twin Zobel networks in close proximity to the MOSFETs sources and ground with the goal of increasing VHF stability. Twin Zobels also distribute Zobel resistor power dissipation, allowing the use of smaller 3-watt metal oxide film resistors that are naturally virtually non-inductive. Diode clamps for the supplies and outputs.Test points are included at the top of the OPS pcb in order to measure & set the OPS bias current conveniently with your DMM. Notes:This design can be used in amplifier configurations other than the Hafler chassis, using two or three lateral Mosfet output devices, depending the the OPS (OutPut Stage) pcb that is used. The design has been tested with the now obsolete Exicon Mosfets, ECF10N20/ECF10P20. The OPS is designed for use in all the Exicon Mosfet packaging options, TO-247, TO-264 and TO-3.This assembly is for customers who have previous experience in electronics, built, repaired stereos and amplifiers in the past to obtain this experience. You must understand how to read a schematic, assembly drawings, bill of materials. You can should be able to identify components/polarities/markings, be familiar with assembly tools, troubleshooting, have the know how to use the required test equipment. Soldering up and testing these new boards requires a fair bit of skill, experience and patients. We say this because we want to make sure that it is within the capabilities of customers who buy them. We do not want to discourage you but also want to make sure a build is successful. We can offer some support, but if you have problems, it will be in most cases an assembly error for which you need to review and inspect your work very carefully. You have to realize that the original Hafler kits were sold with assembled and tested boards. It was done that way for good reason. These new boards are fairly dense with lots of small resistors and tight spacing. Having good lighting and magnification is required. So are having the necessary tools. It is much more involved vs the originals. We have to emphasize this is a task for experienced constructors. Selling assembled and tested boards adds a huge expense, since it is a very time consuming task. We are not setup for manufacture of large volumes. The savings are made when the boards are assembled by the customer. We will consider selling a kit of hard to get parts and pre-assembled/tested boards later on, depending upon interest and demand.If you are upgrading the DH-500(P500), P230 model, please notify us to ship the DH-500C(OPS) or P230(OPS) pcb instead of the default DH-220C(OPS) that is used for the DH-200, DH220, P225 models.We have run this design in a DH-500. A DH-500C(OPS) pcb was designed. It requires that you drill, tap the heatsinks (M3,4-40) to best secure and ground the OPS. If you want to use in a DH-500, ask for the DH-500C(OPS). You will get printed docs, a link to the documents, pics showing the build and the Mouser shopping cart.I have a beta tester reporting that the P500 chassis can use the DH-500C(OPS), the P505 heatsink is different than the P500, so a new P500C(OPS) was designed for that but never tested.There is a DH-220CR(OPS) that is a mirror image of DH-220C(OPS), it allows one to put both AFE and OPS on the same Heatsink surface and not have wires crossAFE is 115mm square pcb sizes do not include the full width with the mosfets mounted, add ~ 4mm to the widthsDH-220C(OPS) is 66 mm wide x 94mm longDH-220CR(OPS) is a mirror of above, meant for mounting both AFE and OPS on same surface and wires not crossing over. DH-500C(OPS) is 58mm wide x 103mm longP230(OPS) is 66mm wide x 103mm long Bob Cordell and myself designed the BC-1 amplifier as well. It is described in chapter 4 of his 2nd edition power amp design book. We created a reference design using a Dissipante 3Ux300mm chassis. It is a complete design ready for construction. Its possible to use some or all of the BC-1 designs infastructure (AC,PS,protection) for a DH-220C mosfet design but it is a new mechanical challenge to work it out.https://www.ebay.ca/itm/225339175513Thank you for your interest and support in making this fine design available.

Price: 400 CAD

Location: Baldwin

End Time: 2024-10-12T15:17:30.000Z

Shipping Cost: 19.03 CAD