TDA2030A Audio Amp

I have just finished repairing my muso mate's Marshall Valvestate 2000 AVT150. Both of the TDA7293 amp chips had fried, apparently a design fault as Marshall soon upgraded to the AVT150X. Replacements were shipped quickly from **LINK** great service btw.

Interesting design, uses a RCA 12AX7 dual triode in the output (made in Russia).

I like the soft sound and suspect that the valve stage does not pass the higher frequency harmonics that can make an all transistor output stage sound a bit harsh.

As for live recordings, The Eagles 'Hotel California Live' is what I tested the amp on after the repair and the sound is awesome.

* Danny M *

Very valid points.

There's also the recording chain, which almost certainly is crammed full of things like power supplies with LEDs on and mixing desks powered through bog-standard multiplugs

Many years ago a friend of mine made a recording (one of many) .It was remarked that the unusual high pitches on guitar were "intriguing ". Much later a pair of underpants was found inside the sound box wrapped round the pickup.

What always amazes me is how live music venues keep the different shows separated.

yes Neil but noise is a different beast.

You have a signal say a finger plucking a string, a transfer function defined by the response of the system (everything between the finger and the ear) anf the output (motion of the eardrum). Fidelity is the delivery of the input signal to the receiver (ear) with no loss of information. Noise from power supplies for example is just unwanted extra input signal.

regards Martin

Studios are very aware of the effects of the room on the sound, mostly they go for well damped surfaces but they also seem to use rooms that are brighter as required. A studio mixing desk is capable of modifying a sound once recorded so starting with the cleanest possible sound is probably a good place to start as it is easier to add than subtract a lot of effects. I think Deep Purple once put the drums in a hotel corridor as they sounded best there, I don't know whether it was just to get Ian Paice in the corridor though

I suppose that the end result of an artists labours could be considered to be a CD and so a sound system that makes the best of what is on the CD is hifi. Some music has the very heavy hand of the producer in evidence especially pop music. The trouble with too much production is it is difficult to reproduce live and can be disappointing if you expect your favourite song to sound like the recording. Pink Floyd use a lot of production in their work but used to make a good fist of playing it live, they used many more musicians on stage and made no bones about how they get the live show done. Playing along to a backing track is not where they were at. Bands caught miming should give the money back in my opinion. Perhaps we should consider a live performance and a recording to be two different products and one will never be the same as the other, thank goodness! A good band will often deviate from the recorded version and this is usually very welcome and makes the band more than just session players paid to reproduce a song, that is not meant to be a dig at session players as they are usually outstanding musicians and often produce excellent work of their own but as a gun for hire they play what is required.

Mike

Surely music is subjective? If it sounds good to you, it's OK. Everything else is psychology.

It's easy to show that the human ear is rather poor at detecting distortion; you place chaps who think they have a good ear in an anechoic chamber and play them sequences of pure sine waves randomly distorted with electronic filters. The listener's job is to grade how good or bad the sound is just by listening to it - no other clues. You've guessed it , most people can't detect distortion in sine waves below about 10%.. They think they can, they can't.

But how people feel matters. Placebos work. Peer pressure works. So, if you're the type who enjoys spending money on 'quality' it's not wasted. But you make a bad mistake if you think expensive kit is essential to proper enjoyment of music. Dare I suggest Tamla Motown sounds better on a cheap transistor radio than it does on a HiFi?

Most recorded music is technically better than the real thing. Very often it is a carefully edited assemblage of segments from multiple multi-track recordings. It is not necessary for the base material to be recorded at the same time, or in the same country, or with the same artists, or using the same instruments. Much processing and editing is done, for example a device called an Autotune automatically corrects off-pitch singing when the star is having an off day. Some music is improved by deliberately adding more distortion, noise or effects.

Even though live recordings are technically inferior it's curious that many people prefer them to studio perfection. Perhaps poor quality and noises off suggest that live recordings are "honest" whereas studio versions are too good to be true. I suggest what goes on between our ears is more important than the equipment.

Dave

I had exactly the same experience at the first le Mans 24 hours I visited in the mid 80's - I arrived about 1/2 hour before the start and saw the cars trickle around on the parade lap. The first lap when they were all going full tilt was just so uncomfortable thanks to the volume and frequency of sound from the engines and exhausts that I ended up moving a distance away - from the <10 feet on the inside edge of a corner.

Sorry to OT a bit though!

Edited By Simon0362 on 16/02/2018 13:42:07

Hi, overall I prefer to listen to recorded music, however, Danny M2Z you mention the Eagles, well there's group that sounds just as good on live recordings as they do on studio recordings in my opinion. Their Eagles Live CD is just brilliant and so is their hell freezes over DVD, which I first watched on video. The loudest live gig I ever went too was Wizzard, man they were so load it hurt my ears, even as far back in the hall I could get, I think I left before they had finished, though their performance was very good, although I did see Roy Wood at an open air gig locally several years later and it was a much better volume level and he was a very good entertainer and sung most of his hits, even the ones when he was in the Move.

Regards Nick.

I remember reading many years ago of someone building an amp and getting a hi-fi enthusiast friend to listen to it. After several sessions of listening to a violin solo and then redesigning the circuit he got the friend to listen to his latest effort. On being told it was still not right, he pulled back a screen and introduced the violinist who had been playing the piece live

Now, if you'll excuse me, I must go and dig out the sub-bass speaker unit and the sound activated disco lights I built in the early '80s from Maplin plans . . .

A late arrival at this discussion. For many years now, I've had a Technics deck on standby waiting for a preamp so I could connect it in to my home entertainment system. Over Christmas the Jaycar pre-amp kit was acquired and assembled. With a new cartridge it was all systems go. After the earthing was sorted, no hint of hum.

The box of LPs from the 60's through 80's was dug out from the back of the garage and a day spent reminiscing. I grew up with those albums and they are ingrained in my brain. However, after such a long time it was now clear how production standards had improved over the years. Sgt Peppers from the 60’s was good but nowhere as good as Relax from the 80’s. The Pink Floyd and James Gang albums had noticeably different production standards as the years progressed.

I spent years working with Jet engines, and the compulsory rifle firing as well as attending many F1 races pre and post turbos. Technically I’m deaf but not at the hearing aid stage yet. Music is in the ear of the beholder, that’s the variable that can’t be tweaked.

Pete

Skin effect is the reason (!) the colour of the insulation makes a difference. Apparently. It's because the pigment molecules from the insulation migrate slightly into the copper where all the signal goes due to the aforementioned skin effect. I'm not making this up - this really was the "rationale" behind the claim... Hilarious.

Jez.

P.S. Grey was best because - get this - it has no pigment in it. Unbelievable. Quite literally, actually!

Apparently Neil Young got very shirty with some younger vfans who complained he didn't play some of his songs like the records. "They're my songs and I'll play them teh way I want to play them".

> Much processing and editing is done, for example a device called an Autotune automatically corrects off-pitch singing when the star is having an off day.

I hate the current trend for using heavy autotune as an effect!

Neil

I once crossed swords with a supporter of Neil Young because I was not immediately smitten with his pet bit of equipment. He sent me a large file of information, and was irked when I didn't read it at once. I think it was when I said that I listened to the music rather than the imperfections that we went our separate ways...

Geoff