I enjoy electronics, building DIY projects and repairing things. Most videos will be electronics related, but I will toss in something random here or there. Enjoy!
Hi and thank you for this extremely helpful tutorial From what i understand the best mains transformer for a dual power supply is a center tapped one ? i have seen in the web some schematics to get a dual power supply from a single secondary winding What kind of issues i will have from not using a center tapped one ? i like the single transformers best I do not know why
Another thing that can be done to assist stability is to increase the value of the resistor going to signal ground through the series capacitor, which is there to shunt some of the negative feedback. Choose a value that gives only as much gain as is required.
Excellent series John! Unfortunately we didn’t spend much time in my Electronic Devices class on JFETs. Most of the class was spent on BJTs and MOSFETs. Thx for your presentation!
At 9:43 you state that Vc = Vcc / 2 = 6V. Correct me if i'm wrong, but for a midpoint bias, it is Vce = Vcc / 2 = 6V and Vc = Vce + Ve so if only Rc = 4.7K is known, you don't know if Vc = 6V.
I experimented with a Pi filter in my power supply and came to the conclusion that a 2mH inductor between the 10000uF reservoir bank and a 8000uF bank almost completely eliminates the power on pop as well as the mains hum. Yes, that's a lot of capacitors, but it's worth it and the sound is more dynamic as well. I did also add a back emf diode across the inductor bank. The power supply plays a very important role in dynamics and noise filtering.
Hey John, I ordered a simple 36V 5A power supply "brick" for this. You were saying the 32 volts setting would make the unit last longer. Is there an easy way to just keep the input turned down or something to help if I still use the 36V supply?
If you want to go budget, buy an old one. I have a Technics and is spot on. Belt driven, 0.045% W&F RMS and it is just one of the cheaper models. New can't beat the past with experience and construction in mind.
And I thought I might be getting the Dual back! Nice looking unit. A better cartridge, a little better servo motor, maybe a slightly improved preamp and they could improve this model or make a second model with these additions for a little more.
The Dual with the 8 pole synchronous motor, better arm, cartridge, stylus and pretty much everything else would take a lot of $$ to beat with a new table.
Hi John My last turntable was some 50 years ago. I really have no thoughts of going back to the poor S/N ratio, inner grove distortion. Poor dynamic range etc etc. Was the platter really made of steel?? I thought it should be of a nonmagnetic materiel like aluminum. It was a long time ago; my memory is as distorted as that phono preamp. Regarding the low output voltage, in the OLD days the RIAA preamp needed to amplify the 3mV up to only 100-150mV a similar level to a tuner or aux input of an integrated amplifier. These days most items have a much higher output, so such low-cost items struggle. I expect such a RIAA preamp does everything on a single chip, that's asking quite a lot. Very high gain and RIAA EQ. I also thought the tracking weight of 3.5 grams was a little on the high side. Most conical budget cartridges of the day Goldring G800, Audio Technical AT66 would track well at 2.5 grams. Just a thought!!
I'm going to give the Dual table my friend gave me a go w/ the ESP phono preamp. It has a higher end cartridge and hyper elliptical stylus. Back in the day, I recall most of my records having a unique sound that wasn't all that good, though my equipment was budget. I want to see what I can get, though I know it can't beat digital.
Nothing wrong with your English, I feel that all of those 'con's' could be sorted quiet easily by them. Cold you put a brushless motor with an ESC on it and set it up ? anyhow if they did fix it up it looks great....cheers. EDIT: just noticed that they use a cheap arsed mains switch to switch speeds and that's naff :)
I made one from a corvette water pump. With the big 14" × 1/2 " metal water pump stabilizer weight. And a long tone arm. It sounded pretty good. But my brother said it looked like crap. So I got mad and pitched it in the scrap. Now I miss Frankenstein. 😅
Hi! Quality components matters more than their number. I own a pair of Infinity Primus 153 and the sound was shut in and dynamically constipated. The crossover had nine parts ( if I remember correctly ), a third order attenuation for both woofer and tweeter plus and impedance/Zobel device. I changed it for a simpler second order filter with better parts, not to expensive, but much better than the iron core inductors and electrolytic caps. The quality of sound jump quite noticebly. Sometimes too many parts choke the sound. With quality drivers, you don't need so many parts to compensate for a bad choice of drivers. I'm now a subcriber!
LED elements fail, because of cost cutting measures. They put too much power into too few modules. If they doubled the number of elements, and applied half the current to each, you could run these CONTINUOUSLY for 10-13 years, with no more than 10% degradation in light output. At that point, the failures would be limited to the power supplies. With the increased efficiency, the bulbs could run on slightly less power, and the cooler operation would greatly increase the life of capacitors, inductors, and other power supply components. I'm happy to pay the extra few $'s for the extra LED modules!
hola ,que raro mucha diferencia de 150w a 50 w reales ..pienso ,no sera q te mide 50 w por que salteaste el preamplificador inversor y por eso no te dio por lo menos 100 w ? mm
Just use Class H amplification, it's a great balance between efficiency, heat, voltage, amperage, and power output.. The RAIL CATCHER! The newer Class H amps. have hardly any crossover distortion..
Hey John, I have a couple questions. 1. have you tried the Hifiberry Amp4? I've been using this and I like it a lot. I power it with a 15V audio grade power supply, and use it on 8 ohm speakers. It does not seem to get hot. 2. why do you prefer 4 ohm speakers?
Sir very nice videos I have learned lots from your videos sir I have a request please make a video about how to select transformer voltage for audio. Amlifier boards.thank you so much for making good video a.
You can use solid state relay and trusty UTC1237 (uPC1237) or other similar "speaker protector" but then again it still added complexity, maybe it's safest to just couple it with "old school" audio trafo and be done with it.
I would never dream of using any amplifier without a delayed start and possibly more important a DC monitor. Changing a relay after 5 years is a small price to pay rather than replacing the bass drivers on a pair of speakers. 30-60 volts across any speaker is never good.
I bought 2 of these preassembled from aliexpress. I opened the first one and connected it to a 12v-0-12v AC transformer. as soon as I turned the power on the tda7293 chip fried. smoked the thing. I believe the chip was bad from the start. I took a few pictures of the amp before I tried to hook it up, and the TDA7293 had several of the legs that looked burnt.. they were darker than all the others. and guess what, that is the side the fried. I'll try the other one later.. it looks ok,, but who knows with these Chinese sellers. there is a few differences, the board I got, has a rectifier built in.
nice to see this often ignored topic , came across a known issue with quad amps where they break into oscillation (405 i think) within the audio spectrum at switch off, a high midrange squeal, i was never impressed with the whole current dumping complexity already then that on top! and no mute circuitry is a bit obsesssive on something consumer grade, ditched that and made my own amps since my own amps just have a 2 second turn on mute and any switch off noise is something that needs fixing. now asus motherboard windows boot up pop is something i need a solution for , a driver update caused it!
@@bobisyouruncle1 yes never meet your hero's, I used to love Aston Martin till my job means I work on them, held together with duct tape and stacks of washers under panels to get the height right, and led headlights (the sidelight bar) where if one led fails the whole lot go out, and anteque sat nav lifted straight out of volvo that's the db9
Back in the mid 80s, i had a little class ab amp with 2x35 watts from poland, called ALTUS V60. The power up/ down pop this thing produced was out of this world, it made the voicecoil of my 8" speakers hit the poleplate more than once. And it killed several tweeters as well. "funny" little amp that was.
Its possible to eliminate the power on pop using a speaker coupling delay circuit with a relay? I saw this in speaker protection circuit when the amplifier powers up puts itself in the protect mode for 1-2 seconds.
