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Great information, need to watch this several times.

This is an Amazing little sub. I have 2 of them. One stopped working just before covid and took it to a repair shop. This guy lost it or sold it. He asked for proof, so I showed him a photo I took of the serial number of the sub......sitting on the floor of HIS shop. A week later i gave him the original Box with the same serial number. He then gave me $450 for it.

I just got the mt21 as well... Hooked it up to an oscilloscope. And switching noise is really there. The way they implemented the filters is truly inadequate... I got it somewhat looking good by adding my own filters. But it sill looks quite horrible

Why didn't you use the secondary voltage for the soft start circuit, instead of using the primary and creating a specific RC timed circuit that isn't really universal for different projects? Just curious. Switch the primary of the circuit, based off of the secondary voltage rising to a certain level.

Would this be adequate for testing tube amps?

as a "known dead" test: Is it safe to say that if any two pins are shorted (via continuity test), the transistor is fried?

AMEN, 🙏 🙏 🙏 🙏 🙏 🙏 🙏 🙏.

Even at 1 ohm nominal load it drives my 2600w quad 6 inch subwoofer to its absolute limit indefinitely all drivers and the twin ten inch passives reach full excursion. The only heat is the power leads running to the 12.6v batteries. For mids and tops I use 4 150w jbls running at a nominal impedance of 2 ohms... phenomenal little amp. Because of its analogue gain it is substantially louder than its big brother the 760w SY-S350H requires twice the voltage.. I wouldn't do what I do with it at any higher voltage tbh.

This is not from the original recording. The drums on the record are acoustic, these are electronic. Sounds like a bass and drum cover

Sir, is it ok to use 19v laptop power adapter?

check all caps !!!! one or more may be short

I'm messing with a Cambridge Audio 640A. Had a shorted output transistor. Replaced both on that channel. Worked fine till I turned the volume up and a power resistor combusted readily. It's back in a cupboard.

True, but you don't mention any of the downsides. In moderate amounts (below 15db), NFB actually increases harmonic distortion above 3rd order. So you need lots of NFB to reduce the higher order harmonics, which necessitates adding more gain stages... which increases open-loop distortion. And due to phase shift and gain of the NFB loop changing with frequency, you get intermodulation distortion (IMD) which is particularly nasty, and transient IMD on percussive sharp attack sounds. Also the NFB loop essentially doesn't work at very low and very high freq, causing instability at those extremes due to the high gain, unless compensated. These things were not well understood in the 1950s when guitar amp topologies were set in stone. You definitely don't get something for nothing. I've yet to hear an amp that sounds better designed with NFB. The average guitar player may not notice, but when you build your own amps and listen, you start to hear the differences.

"Oh, sorry, I guess I'm the only one here with dead things inside me." -Smart IIIs

I also purchased a 2.1ch amplifier that uses an IC called "CS8673E". This amp also adds a lot of noise to the music. I understand how you feel. Let's throw this thing away! !

I must say I like your style sir! Also your video was quite informative.

Jag önskar att den där tamburinen kunde ha mixat bort. Då kunde man ha fått sig en bättre lyssning, men man kan inte få allt 🙂

Hey, thanks for inspiring me to do that double sided pcb. Came across your channel and had a couple of those SC115 originals I got 2nd hand years ago... hadn't been able to find the schematic before finding this clip. If you're interested, I have some spare boards. It's a wee bit modified and happily running at +/- 62V, needs a really big heatsink into 4 ohms lol, cheers

And who is the Bassist?

Are you effing kidding me? WOW! DEVASTATING.

I've never been this angry about earraep before. Why you do this.

easy amp to fix

there are replacement modules made from discrete components that are pin compattible .. you just need to use google !!!!

This is an awful - witist did very well to keep up with the dumpster fire(s) he was up against

Are those M3.5 screws for Jaycar's right-angle standoff brackets by chance?

15000uF caps? You don't see those too often! Looks like a nice unit that was well worth repairing (even if not for a huge profit).

the real scene

It is cold over there? I can see that you have the electric heater on!

Always nice to see you at work.

The way it is done is reversed normally Normally open contact is in the output of the amp. Then normally closed is grounded. And the common is connected to the speakers That way the speaker is protected.. it also does not destroy the relay.. ...

@ 14:15 If you only want the circuit to amplify ac signals & not dc, then insert an electrolytic cap in series with the 4k7 resistor to ground. Around 100uF. This will give a gain of 1 at dc [1 + (10k/infinity)], ensuring that the output of the op amp sits at half rail. At audio frequencies the capacitor will be bypassed giving a gain of 3.

@3:30 Dividing by zero does not result in zero. It results in infinity. The smaller the denominator, the higher the result.

its a bit How Ya Goin .

Notice there's no ounce of bass in this song (ie. bass guitar, synth, etc).

Why padding on the back of the speaker wire terminals? I've seen subs with built-in stereo amps for the mids/highs with those terminals on them. On those, the padding prevents air leaks in a carefully designed cabinet.

How are you mate Is Siliconchip SC480 amplifier is High Fidelity or is it a Public Address amplifier IF it is High Fidelity how is the audio quality. My taste is Warm British sound. Please reply. Thanks

I use a passive high quality attenuator ballanced XLR with short cables for the sig gen with no noticeable deterioration. Can pull it down to 50 mv RMS no probs.

In the reference circuit diagram of datasheet, I can see an inductor in the speaker output line, but I can't find an inductor in that product pcb. Is it possible to output from the Class DMP without an inductor?

Wheres skeptic now lol

Looks like a noise loop

Not worth the $2

Well as you said, it may have been a time waster, but it is good content for the channel. I am considering to buy one of these and I was checking if it is robust (switches, input selector, etc) and it seems this Nak is built rock solid.

It is a song from my youth, I would have liked you to play it first and then teach us the fingering, greetings.

I suggest you to don't put in a preamp. Better if you build a preamp separately in other chassis. Like that the preamp you can used with different amplifiers.

You also have made a mistake, the capacitor connected to pin4 is a 10uF why did you write on the schematic 100uF ?

Did you get the fake one?

Any interest in making your own beefed-up microphone to fit inside the existing case, to take advantage of the design and stand? I'd be curious to see you make your own microphone.

The fact you both think you won this is hilarious. 😂

great video it looks like that is the top panel? personally would have had the bottom panel the top. but its looking good...

you should fit the heatsink where is the ventilated area like that the heat will be dissipated much easy