Lateral mosfet amplifier schematic. Lineup’s amplifier works 10n20 and 10p20.

Lateral mosfet amplifier schematic This amp uses EXICON ECX10N20 Lateral MOSFET TO-247 in output. This was fixed with one 22pF from base to collector of KSA1381 and likewise 22pF around KSC3503. 3. Desirable features of these devices include a threshold voltage of only a few tenths of a volt and a zero temperature coefficient Figure 4 - Simplified Schematic of Complete HEXFET Amplifier. ) Input power 10 W max. JPG. But I liked to refresh this fine project by Mark Houston ( AUS ) and update it: DIY Class-A 2SK1058 MOSFET Amplifier Project. Using IRFP150N MOSFETs as both the amplifier and current source, In my previous PCB I used Exicon ECX10N20 and ECX10P20 MOSFETs. EBB 150 Mosfet Power Amplifier Module 125W RMS Audio Disco PA | eBay I just designed and built an amplifier using similar circuit as Maplin mosfet amp but using ALF16n16W/ALF16p16W dual lateral mosfets. Joined 2011. Only “Referring to the amplifier schematic, Q1 forms a differential pair, with the amplifier input connected to one side and the feedback point (divided by 16 via R48 and R49) on the other. Ussa 3 fab nice but some parts Please show your schematic. 8mA per JFET (1. Check Details. anyway, the irfp240/9240 twin does have negative temp coefficient throughout its operating range, if i read the chart correctly. 04-26-2014, 12:16 AM. 20np20 and 20p20 look different mosfets about input capacitance and load. The lateral power MOSFETs are presently the most widely used MOSFET in audio amplifiers. Project 101 - High Fidelity Lateral MOSFET power amplifier. Hybrid Amplifier By Andrea Ciuffoli Newbie to DIY audio, looking for a class-A, single-ended MOSFET power amplifier schematic. The amplifier is built around the Hitachi 2SK1058 N-Channel MOSFET. Share. $2 for 1-4 Layer PCBs, Get SMT Coupons: https://jlcpcb. Tags: None. Then vertical types were invented at that time. DJScythe. com here I have attached the downloadable pdf Now I am ready to start over from the beginning with a new design from Bob Cordell book. , maybe 50k on the 1k scale of a passive ohmmeter). 0°C/W ABSOLUTE MAXIMUM RATINGS T Storage Temperature Range -55 to +150°C V Drain – Source Voltage 200V V Gate – Source Voltage +/-14V I Continuous Drain Current 8A I Body Drain Diode Current 8A P Allowable Power Dissipation* T = 25°C 125W T Channel Sure, you can, and have an underperforming or nonfunctioning amplifier. Typically +-35volt rails would work just An input signal of 2 Vp-p is first [highly] attenuated and then amplified (by a factor of ?; could not tell from schematic) to generate an output signal of 0. Efficiency: 57 % - 76 % IMD at 300 WPEP < -26 dBc Load mismatch: 3:1 (all phases) Description The STEVAL-TDR004V1 demonstration board is an RF broadband power amplifier intended Figure 1: Single-Ended Class-A MOSFET Amplifier Schematic. Reed Zieme 06 Oct 2024 . hongrn. P. It uses 2SK1058 / 2SJ152 lateral MOSFETs. 1, and it is about as simple as a high power MOSFET amplifier can get - it is considerably simpler than most, but lacks nothing in I open these thread for these all Hitachi Lateral & Jfet amplifier. 3 to v1. Maybe someone has more details about this ? regards, Tibi . The amplifier operates from a +45/-45 V DC dual supply and can deliver 100 watt rms into an 8 ohm speaker and 160 Picture 1=Single ended v1. Join Date: Sep 2005; Posts: 3028; Share Tweet #2. A Paul Kemble web page - JLH mosfet amplifiers. I want of course reuse them. 0009% 1W 8ohm in SPICE Simulation. 0002% at 1 I took the basic Hitachi MOSFET circuit and added various improvements from the Doug Self "Blameless" approach. So what if we combine the two. Log in. By mistake got some dc from comp soundcard out( have not input cap) and R21-20ohm smdis now open. It uses lateral MOSFETs instead of bipolar transistors for their thermal stability. 4x schematic is compiled of info from this hole thread, it should be close to the shipped copyrighted layout version. 4 schematic, but it is on BOM. I only saw the zeners Is possible to change in the 200 Watt Lateral Mosfet Amplifier the output device 2sj 352 and 2sk2221 with irfp240/9240? If yes, how to do? p. 2mA per side (2. Yes lateral fets are expensive but sound great in a well designed circuit. Changes from published schematics (v 1. A schematic and pin diagram for the 2SK1058 is shown in Figure 2. Today. Figure 2: More then 30 years ago (1985) I build the Elektor AXL class A/AB amplifier, time to upgrade this amplifier using new (= better)components. R. 2022-03-19 7:40 pm #1 2022-03-19 7:40 pm #1 Title mostly says it all. Joined 2021. PMI. P. final. For the simluation to be as close as the original book schematic, I The circuit was inspired by the original amp schematic in the Hitachi lateral MOSFET data sheet. 11. I suspect that the inspiration for the Kemble circuit came from the same place, as the topology is similar. Audio Amplifiers. Save . excuse my Project 35 utilizes the same circuit from the previous project that uses a symmetrical differential amplifier input stage. 4 KB · Views: 130 M1 N Channel Lateral Mosfet (T = 25°C unless otherwise stated)C *Thermal Resistance, Junction To Case 1. 100 Watt Power Amplifier Circuit Diagram Using Mosfet. The previous build of a that run at around 20mA, resulting in an overall amplifier idle power of just over 2W, unheard of for lateral MOSFETs. Attachments. The design was updated with lower noise JFETs for the input stage and This reference DIY project details of an upgrade construction for the legendary Hafler DH-220 lateral MOSFET power amplifier, which can also be used to upgrade other Thanks again to Jeff for sending me the boards and the components to assemble this. sound-au. " What is not well known sa2016_lateral_mosfet_double_die_rev1. the normalized resistance (Rds) goes progressively higher as die temperature goes up - granted, it doesn't seem to go up as fast as those hitachi lateral mosfets. The pre drilled transistor mounting bracket was very helpful. samritatrust. Watch. That project can be problem about bias with 20n20 and 20p20. Mount them straight and against the PCB SK3: 3p "Mains in" SK4: 3p "Mains transformer" SK5+SK6: 2x 2 pole Transformer output * First slide these two connectors in each other. In the original design, lateral power MOSFETs were required that regrettably are no longer manufactured by Hi, For the Baby Huey amplifier (designed by yvesm and gingertube) I have made 3 different PCB, one very simple for two ECL86 or PCL86, a more complicated one for one ECC83 and two EL84 with a MOSFET driver stage and a similar schematic but for EL34 output tubes to have more power ( I setup the circuit from your diagram. Seasoned Veteran. Thread starter DJScythe; Start date 2022-03-19 7:40 pm; Jump to Latest D. AdamZuf. It can be seen from v1. Design and development of the boards by @geoffw1 are in post #1678 Gerber Files and BOM for SMD version ----- Attachments. I hope some guy is willing to draw PCB files, when the time comes. In High performance Audio Amplifiers Circuit 2. 12. Gain is set at 2X. wahab. png. 1-2 Vp-p across your headphones. The current of MOSFET is 1. any body has a schematic with components values for esp project 101 i heard is very musical and extremelly powerfull thanks . Project 101 - High Fidelity Lateral MOSFET This is my new 6 Watt amplifier. The amplifier for which you provided a circuit is a poor example of a MOSFET amplifier, and your speculation Very minimalistic Power Amplifiers. I love the sound of jfet and mosfet. Added shunt compensation to VAS Removed gate resistors Added . The Hitachi Mosfet datasheet (and thinking back, it must Exicon Lateral MOSFETs. W. Here is a link to original article, with a picture of this amplifier & schematic: Specifically designed for audio amplifier applications High thermal conductivity Excellent frequency characteristics Integral protection diode Free from current concentration, resulting in a high resistance to electrical destruction. This is using a +-70 volt supply rail, lower supply rails can be used on this module for lower power outputs. 10. High power mosfet amplifier circuit diagrams Blameless style lateral mosfet amp Amplifier mosfet audio circuit schematic watts circuits diagram power watt diagrams projects electrical electronics student rf wiring gr next. com/DYE 400W Real Power Mosfet Amplifier | Amplifier Testing | Schematic & PDF. I've split this up in to two parts, as the video was getting very long an It seems I made a mistake. Joined I thought all mosfet have negative temp coefficient, but i could be wrong there. A 50W lateral MOSFET amplifier based on David Tilbrook's AEM6000 A 50W lateral MOSFET amplifier based on David Tilbrook's AEM6000. Mosfet power amplifier circuit diagram : first simple mosfet amplifierAmplifier power mosfet lateral audio amplifiers amp upgrade pilih papan project circuit diagram Amplifier mosfet power circuit 100w audio diagram ESP Project 101 Lateral MOSFET Amplifier LM4780 Parallel Chipamp Sonata Soundbar Project The Renditions - Active/Passive Towers. My main goal was to replace the power mosfets 2SK134/2SJ49 with Exicon ECF10N20/ECF10P20. EBB 250 mosfet amplifier module schematic . Use the design from previous post #90, 50w MOSFET amplifier circuit OCL using K1058 + J162 | ElecCircuit. 2012-10-07 1:31 am #37 2012-10-07 1:31 am with the kit, if you bought 2 amplifiers for stereo then one amplifier can be built with red connectors (right amp. Joined 2013. s. 005% and THD1 < 0. The high gain and broadband performance of these devices make them ideal 1500w Power Amplifier Electronic Schematic Diagram. 0005% (if possible in the ppm region 0. RCA connectors. I'm enamoured with my lovely old NAD 3240PE amps (I've gotten a couple working, and they're a nice amp). I remember my first Maplin lateral mosfet amp around 1980. Amplifier mosfet 70w schematic stage I followed the Class A MOSFET Amplifier Schematic with the following exceptions. Lateral MOSFETs are a much simpler structure, where the gate oxide One to two milliamps should flow into this pin to bring the amp out of mute. 3 schematic Picture 4=Single ended v1. ESP Audio Projects - Lateral MOSFET Power amplifier for Hi LC need a help with my VSSA I have bild and everything was ok. Re: Class AB MOSFET Amplifier Build 2. DS20005447A-page 1 LP0701 Features • Ultra-Low Threshold • High Input Impedance • Low Input Capacitance • Fast Switching Speeds Congratulation. You can easily understand why the author called it ZCA: Zero Components Amplifier. Member. Shop. R_Mydlar. g. MOSFET power amplifiers have gained significant popularity in Amplifier mosfet 100w watt transistorsMos fet power amplifier schematic Mosfet power amplifier pdfA lateral mosfet power amplifier design (second try). Therefore each Introduction. 4) that I discovered so far: Input filter frequency changed. org. Discover what Exicon Lateral MOSFETs can do for your audio designs. 6mA total) Stage 2: 1. Sign up. I will be finishing up with the SD2933 N-channel enhancement-mode lateral MOSFETs Features Excellent thermal stability Frequency: 1. Output Device. I be back later with details and schematics. Therefore thermal dissipation of each MOSFET is 24W (16Vx1. Q7 and Q8 form a 5mA current sink to This has the advantage of stunningly low Rds and hence high efficiency, but does nothing for linearity or capacitance. 20 Here we describe the circuit and adjustment of the DH-220C Lateral MOSFET Power Amplifier that was published as a construction project in the July and August 2021 issues of This article offers the first serving of an amazing DIY project from amplifier experts Bob Cordell and Rick Savas with an upgrade for the legendary Hafler DH-220 lateral Lateral Mosfet AdvaLateral Mosfet Advan nnntagestagestages The key advantages of lateral mosfets over bipolar junction transistors (BJTs) and vertical design of the amplifier circuit. I like my lateral MOSFET amps, but I dislike excessive quiescent power consumption. I think I would have rotated the PCB's such that both pairs of MOSFETS are against that heatsink. My choice would be, from his suggestion, the IPS and VAS design of figure 9. The schematic of the amp is shown in Fig. 00000x). 2021-12-29 2:43 am Lateral MOSFET output amp. com. 4x in very small distortion In every type of amplifier, be it vertical MOSFET, lateral MOSFET or BJT, one will always have bad examples of performance and sound that may tempt one to make generalizations about that technology, and this we have to be careful of. The amplifier was designed by Paul Kemble (head of NAIM company) Now for these amplifier the mosfets are Browsing the web looking for interesting amp circuits specifically using lateral mosfets and found this one on electronics-diy. 183. Joined 2009. I am completely new as far as DIY audio is concerned, but I know my way around a soldering iron My recollection is that MOSFETs (lateral types back then) were quite popular when they first came out but people gradually realized problems using those devices and started to cool off. 6 KB · Views: 38,857 M1 1Khz 1 Watt FFT Simulation plus Servo Plus Exicon Models. It worth that extra cost. The purpose of this paper is to demonstrate the level of performance achievable with current technology and to illustrate practical circuit techniques for achieving this performance. It uses a pair Exicon's Dual Die Lateral MOSFET's, the power output from this small module is quite impressive at around 340 watts RMS into 4 ohms. I've attached the most recent schematic to this message. nigelwright7557. PCB's are available. Instead of the 2SK1058, I used the 2SK2221 mosfet which I had on hand. Power Supply: Power is provided by a 800VA 40VAC-0-40VAC Later, Strickland joined Hafler and designed the Hafler 9300 power amplifier: Click on schematic to see enlargement Note the complementary balanced/symmetrical input stage and VAS Hi Abetir, The front-end (IPS+VAS) is fine, but the output stage is a problem for two reasons: 1) No thermal feedback. I compared the datasheets of the 2SK1058 and the 2SK2221 2018 Microchip Technology Inc. The best thing I have done my jfe2140+tda7293 composite feedback amplifier and I think it's one of the best chip amplifier applications I've ever heard. asc. The first thing I noticed is that circuit needs some compensation to be stable. I dont see any 20ohm resistor on ESL0113 rev1. The amplifier is working fine and uses MJL3821A/MJL1302A BJTs as the power output transistors. Had vertical types were first to the market, we might be calling them "audio application MOSFETs". Rather than BJTs in the power output stage this time it’s MOSFETs, arranged in a source-follower configuration. Click to expand 🙂 This is one good mosfet amplifier 🙂 No doubt about it if we have some basic knowledge we can easily figure out components values we probably have 200-300 persons at this forum that can do this As this VSSA Lateral MosFet Amplifier. Perfect for audio projects and DIY amplifier enthusiasts. I did not use feedback and I am not a fan of mosfet relais between speaker. From your description it isn't clear how you have it connected, there is no such thing as a "common emitter" MOSFET amplifier but I think I know what you mean. Bias currents are as follows: Stage 1: 0. Gerber Files and BOM for an SMD version of this amp. co. Class A Mosfet Amplifier and PS and here: ZCA 5 watt mosfet amp. EXICON lateral MOSFETs are designed specifically for high fidelity integrated and power amplifiers. This design uses a high performance audio op amp to provide the gain for a current feedback mode power amplifier and is the basis for the Amplifier Modules shown on page 1. 4x schematic Picture 3=Single ended v1. Now that I have ended LU1014D Small Amplifier. This means you should have very large heatsinks to avoid problems with bias runaway. Designed for broadband commercial and industrial applications with frequencies from 865 to 895 MHz. I used a forced air cooled heatsink for a pair of MOSFET(top and bottom ones). 2017-02-26 4:37 pm This is not a problem with a high bias Lateral mosFET output stage where the devices are virtually self compensating you can't compare with First Watt, they all use Vertical mosfets, which don't have the same unlinear input capacitance problem that Lateral mosfet have, see the ciss curves in the datasheets. Also the medium power transistor BF469/BF470 changed to There are no lateral MOSFETs in the TO-220 case that I'm aware of, and all true lateral high-power MOSFETs use the TO-247 case or a small variation thereof (TO-3 lateral MOSFETs may also be available, depending on supplier). There's this one on eBay which I believe uses the same circuit but with modern Lateral MOSFETS. This amplifier has THD 0. That's why I definitely need help from those who know this job. uk. 2021-12-31 7:03 pm A Lateral MOSFET Power Amplifier Design (second try) My DIY Amplifier has a small sizzling sound; with the HBR resistor added, and a totally new traces strategy. A further modification that a reader (thanks Shaan) has tried and tested is shown above. Op amp based current mode driver. Electronic Schematics. Fully complementary floating JFET input stage biased at approx 3 mA per JFET, Darlington VAS'es, 2Sk1058/2SJ162 Lateral FET output stage biased at 180 mA per Lateral FET. In this schematic, if the source of the +Vrail is on the right of R46, the R10 don't isolate the MOSFET! My understanding of the layout of this schematic is that the +Vrail The output devices are popular Hitachi(now Renesas) Lateral MOSFETs having positive temperature coefficient that inherently protects the MOSFETs from thermal N–Channel Enhancement–Mode Lateral MOSFETs. Then I looked at the We knocked some up and were quite taken aback by how good they were - especially as we were in a 'mode' with our designs to see just how complex we could make them. Lateral MOSFETs as the ones used in this schematic, do not require temperature compensation for idle cuurrents above about 80mA, which is the setting that should be used. Explore the circuit diagram of a high performance lateral MOSFET power amplifier designed for high power and fidelity. Yes I did follow for a while the Fetzilla amplifier great design but how I stated I want higher power amplifier (I have 40-0-40VAC) transformer 700VA. A lateral mosfet power amplifier design (second try) Here is schematic from apex for IPS and VAS example that will add 4bjt to IPS and give hybrid sound to amplifier (try to simulate using jfet as on your schematic and adding bjt ccs but replace zener diodes ccs with 2xbjt with red Without a schematic with numbered components & Test Points, it is impossible to work out what is going on. This is an amplifier for a bass guitar and will be powered from +/- 60V rails. Amplifier mosfet audio circuit schematic circuits watts watt diagram power diagrams projects electrical electronics Figure 4 - Direct Coupled Power Follower Using MOSFET Current Source. 4mA total) Stage 3: 10mA Output MOSFETs: 50mA Compensation is straightforward, with poles provided by C3 in series with R11, I would like to keep these as a high power amplifier, that is the reason for 2pair power mosfet. 5 KB · Views: 4,389 I have never tried it in case the limiter does not work and I blow up a good amplifier. Any difference with your linear psu version ? Too early to tell, ELCOs need some 50-100 h to settle down, so hard work upfront me hehe :cool: Discrete designs are a high-level job for me and I have a lot to learn. My goal is to do My MOSFET amplifier designed for music. Launched in 1993 and improved in 2015, the current range is optimised to offer great advantages to the design of high-end linear amplifiers. It went together well. Joined 2008. 5A). Except for First Watt F7 which uses only 4 actives, including a pair of Lateral Mosfets for the Hooked up both amp modules today for the first time, to some crappy gaming headphones from Sennheiser, but it sounds very promising. We who don't know your schematic has to disassemble and measure smd caps . The output stage schematic is shown in Fig. Reactions: Haze Head, cowanaudio, dliscomb and 1 other person. The DC-offset is very small, 12 mV. 6 - 54 MHz Supply voltage: 48 V Output power: 400 W (typ. 150 Watt Amplifier Circuit. The op amp drives a low impedance load, and the rail currents of the op amp are first voltage working DH-220 or other Hafler MOSFET power amplifier, it is highly recommended to test them for shorts, functionality and operating gate voltage (V The lateral MOSFET has an N-type or P-type channel connecting from the drain observe an open circuit or high resistance (e. 277. Last edited: 2012-10-07 1:31 am. Maxpow should read what I wrote to the last person i quoted. A bias circuit as proposed above will Hi, I want to know what is the selection of high power mosfet (N channel) for audio amplifier purpose. In the typical output stage shown in figure 6 the driver stage can swing to within about 1V of the rail (the If anyone is interested in this subject, I would be happy to share more info, and schematics as well. "R1 and R2 provide some additional stabilizing isolation between the relatively high gate capacitance of the lateral Mosfet stage and the VAS. Please, will you allow someone to post a schematic with component & Test Point numbers? ••• More options. Currently I use 2sk 3911 (Toshiba), seems it has high spec (600V, 20A), but very high input capacitance (around 4nF). 6_schematic. I used his design as a starting point and then went a little further. And don't waste current to get there. The demand for high-power amplifiers is increasing rapidly due to the ever-growing need for efficient audio amplification systems. But; do you really need this potent amplifier [or any ] to do this proposed job? A more Explore the circuit diagram of a high performance lateral MOSFET power amplifier designed for high power and fidelity. So, on post # 4 the amp circuit ( one channel shown ) and the power supply. Lateral Mosfet AdvaLateral Mosfet Advan nnntagestagestages The key advantages of lateral mosfets over bipolar junction transistors (BJTs) and vertical design of the amplifier circuit. Aim to improve on the distortion specs by, say, 20dB. Here is my take at it. and i heard that theyre very good and low thd transistors also at low bias. 5A and voltage is +/-16V. device speed. The THD distortion at 1 Watt is remarkably low for such a simple amplifier: THD 0. Then I looked at the Lineup's Ultra allows for ECW20N20 / ECW20P20: Ultra Amplifier with JFET input and Lateral MOSFET out I designed the PCB's for this and am writing a build guide (just about done). Lineup’s amplifier works 10n20 and 10p20. does anyone have a good My version of the Lateral Amp Tino96, You requested a deisgn based on Anthony Holton's Lateral FET amp. A. Visit. Author Mr. my friend gave me 6pairs of 2sk135/2sj50 transistors. Lateral MOSFETs (as used in P101) have exactly the same issue, but the curve changes from negative to positive at a much lower current (around 100mA), Mosfet power amplifier circuit diagram : first simple mosfet amplifierAmplifier power mosfet lateral audio amplifiers amp upgrade pilih papan project circuit diagram Amplifier mosfet power circuit 100w audio diagram Re: ESP Project 101 Lateral MOSFET Amplifier Looks good. My friend and I who have been working on this project want to try something different, and use the ECW20N20 and ECW20P20 lateral MOSFETs to see if the bandwidth/slew rate/distortion might be improved hi. 0052% 🙂 This measurement was taken with sagging rail voltages from power supply (~ +/-58V) just before power supply current limit: I have used the Maplin original circuit except for 390R gate resistors and ALF16N16W and ALF16P16W lateral mosfets. gannaji. 4x schematic Picture 2=Balanced v1. AndrewT. 2013-10-28 1:26 am #2,712 2013-10-28 1:26 am #2,712 kgrlee said: Without a schematic with numbered A 100W MOSFET power amplifier circuit based on IRFP240 and IRFP9240 MOSFETs is shown here. I. Close to the distortion levels stated in the Hitachi original article. ) and one with the black connectors. I use IRFP240/9240 devices in this. 4 schematic The version 1. Examples of this structure are the Hitachi 2SK-134 (n­ channel) and 2SJ -49 (p-channel). 82. Reverse the Hi everyone, I'm projecting a lateral MOSFET amplifier using BUZ900/905 pair, but my intention is to make an amplifier that can deliver 200 Wrms to a 4 ohm load and 100 Wrms to 8 ohm, with 30 dB of gain, and with THD20 < 0. jpg. You might have differential temperatures as-is, which means "optimal" bias might be too high for the nearest pair and too low for the farthest pair. 2020-04-02 12:15 am #37 2020-04-02 12:15 am #37 MOSFET based amplifiers as we all know are outstanding with their sound qualities and they can easily beat the performance of other counterparts based on power transistors Lateral Mosfet Amplifier Schematic Mos Fet Power Amplifier S. Of course, the overall design of your amp can readily do this. 2SK1058 & 2SJ162. I Hope you like it. Bias is set only with resistors. For comparison purposes, at 10W output power This amplifier design is based on David Tilbrook's 1981 AEM5000 amplifier. Member SA2016: using lateral mosfets ECW20N20 ECW20P20 Test conditions: +/-62V regulated; RgateN 270R; RgateP 180R; overcurrent protection in situ THD20k+N@200W@8R: 0. A Lateral MOSFET version of the 3240. Considering another kind of MOSFET to get more clear, nice sound of my This is one of my latest amplifier modules. murtonpikesystems. It's Built a working amplifier yesterday and the specs are quite good now. Nice amp, I have done also with that current source however that is a tube, and I have the mosfets dc coupled to the tubes, that is possible with a dc servo and a pauze into the speaker protection, I set it on 1 minute so tubes are warm before switch on. . Below are some shots from schematics described. 1 KB · Views: 1,188 R. Joined 2004. Explore. 🙂 I do not know the details of this MOSFET you are asking about. By Guest Suzyj December Schematic R44,45, parts list I remember my first Maplin lateral mosfet amp around 1980. Output inclusive compensation was one notable idea I thought The power supply used for this single MOSFET class A power amplifier circuit is 18VAC and 160VA EI transformer attached to a bridge rectifier of 25 amp to So I began carefully inspecting the newer(~2004) Samson series SX1200/1800 schematic and quickly found that they are essentially the same amplifier without the lateral MOSFET's circuitry complexity, so started tracing the PCB on the Samson S700 and found that I can simplify the amplifier on-place with a simple and clean modification, which also MOSFET is still more expensive than a 150-W bipolar transistor, the premium is small when considered rel­ ative to total amplifier cost and improved performance. I checked the schematic of Holtons symmetric amp and didn't see the Vbe multiplier since it was drawn so far away from the output stage. Setting the bias with a simple trim pot is fine if you use the Lateral MOSFETs (like Hitachi's K1058/J162), but with the HexFETs you use, the spreader, placed on a heatsink with the output devices, is a must. Thread starter Lazy Cat; Start date 2012-12-15 At least you know your schematic. mizkmgsr bah xiaw bwcdrxf car cdro fjn bagpp fjule szzxce