TDA2030A Audio Amp

[Neil WyattModerator @neilwyatt]

Posted by Peter Spink on 15/02/2018 10:09:06:

Surprised this hasn’t come up in the thread so far.

**LINK**

Discuss!

Pete

Intersting.

The FAQ says they can't explain how it works because it's patented… which is a bit of an odd statement!

[Joseph Noci 1Participant @josephnoci1]

Nuvistor's used in an Audio Front-end? Interesting. At around 11 years old I used 1 Nuvistor each in a set of 'Walkie-Talkies' – On 432MHz, or thereabouts..Regen receiver which transmitted nicely as well. 5 x9volt batteries for HT and 2 penlights for heater..

Someone mentioned 807's being used in an Audio amp as well – Did not think of that, but did use 4 of them in a 80m AM ham transmitter amplifier ( 3.710MHz..) – Actually, I lie–The AM modulator used two 807's as well! So that was an 'Audio Amplifier' of sorts.

Joe

[john swift 1Participant @johnswift1]

 

Hi Joseph

the nuvistor was used in the video amplifiers for the 4 video heads in the Ampex 2-inch quadruplex vt

https://www.revolvy.com/topic/Quadruplex%20videotape

 

the Nutube double triode valve looks like a gimmick using the technology and assembly techniques from the vacuum fluorescent display

john

 

 

 

 

 

Edited By john swift 1 on 15/02/2018 20:20:04

[john swift 1Participant @johnswift1]

Hi Neil

the TDA2030 was good enough to be used in broadcast audio distribution amplifiers like this

 

Edited By john swift 1 on 15/02/2018 21:00:38

[Ed Dinning 1Participant @eddinning1]

Hi Gents, 807's have been popular as amp valves for a long time now. Geloso made many commercial amps on this basis.

Due to the increasing prices for the popular (EL34. KT66 etc) valves, TV line output and similar types are now being designed in. These are valves designed for pulse operation so do not have such a linear response for Vg to Ia.

A circuit technique has evolved for this. The signal is now DC coupled into G2 (quite high level and low impedance) which has a nice linear characteristic. G1 is used to set the bias level on the valve as normal.

Ed

[Martin KyteParticipant @martinkyte99762]

Intrigues me all this talk of sound quality and auditoria. There are two ways of approaching the idea. The first being that the sound is only and wholely the playing of the original instrument and singer and that anything coming after that messes with the sound. The second is  that the entire system is taken into account from the instrument or singer to the final listener ifit be live or recorded.

In the second case it is perfectly reasonable to consider all the steps along the way as being part of the intended sound. The acoustics of a concert hall change the sound in just the same way that the resonances of an instrument do. Therefor the hall becomes part of the instrument and cannot be said to be detracting from the sound quality. There are of course rubbish hall acoustically just like ther are rubbish instruments. In a similar way consideration of the dynamics of sound systems can be factored in to the original recording. This is exactly what the Dolby system does. It modifies the original sound knowing that the sound system will restore the intended frequency response.

There are indeed churches with hollow tuned pillars that work better with music in particular keys than others and resonances that suit some kinds of music better than others.

regards Martin

 

Edited By Martin Kyte on 16/02/2018 09:17:28

Edited By Martin Kyte on 16/02/2018 09:19:12

[Danny M2ZParticipant @dannym2z]

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 *

[Neil WyattModerator @neilwyatt]

Posted by Martin Kyte on 16/02/2018 09:17:07:

Intrigues me all this talk of sound quality and auditoria. There are two ways of approaching the idea. The first being that the sound is only and wholely the playing of the original instrument and singer and that anything coming after that messes with the sound. The second is that the entire system is taken into account from the instrument or singer to the final listener ifit be live or recorded.

In the second case it is perfectly reasonable to consider all the steps along the way as being part of the intended sound. The acoustics of a concert hall change the sound in just the same way that the resonances of an instrument do. Therefor the hall becomes part of the instrument and cannot be said to be detracting from the sound quality. There are of course rubbish hall acoustically just like ther are rubbish instruments. In a similar way consideration of the dynamics of sound systems can be factored in to the original recording. This is exactly what the Dolby system does. It modifies the original sound knowing that the sound system will restore the intended frequency response.

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

[Gordon WParticipant @gordonw]

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.

[Martin KyteParticipant @martinkyte99762]

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

[Mike PooleParticipant @mikepoole82104]

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

[SillyOldDufferModerator @sillyoldduffer]

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

[simondavies3Participant @simondavies3]

Posted by Martin 100 on 15/02/2018 10:40:12:

Absolutely, and just as well as one concert , maybe in the late 80's / early 90's caused me to curl up in a ball and hide behind the seat in front to try and avoid the painful bass that coincided with the resonant frequency of my chest cavity. I must have been around 30 rows from the front so who knows what they were feeling closer to the speakers. If could have moved without vomiting over everyone I would have walked out. P.S. No drink was involved!

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

[Nicholas FarrParticipant @nicholasfarr14254]

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.

[FarmboyParticipant @farmboy]

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 . . .

[doubletopParticipant @doubletop]

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

[JezParticipant @jez]

Posted by Geoff Theasby on 15/02/2018 10:56:23:

I have taken a special interest in 'audiophiles' ludicrous proposals regarding fuses, cables, connectors, etc. Whenever I want a good laugh, I head for the previously mentioned Peter Belt's website, and others, praising oxygen free copper cables (All commercial copper is oxygen free, house wiring, water pipes, steam locomotive fireboxes etc., it's in the nature of the refining process) square wire, skin effect (at audio!) sticky labels or grains of rice resting on top of the speaker cabinets, there is no lunacy which they ignore. And the cost! £25 for a 5p fuse with a label stuck on. It's been 'conditioned' you see, for xx hours and didn't blow…

Geoff

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!

[Neil WyattModerator @neilwyatt]

Posted by Mike Poole on 16/02/2018 12:48:13:

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.

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

[Geoff TheasbyParticipant @geofftheasby]

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

[Author]

Posts