Amplifier tuning Software????

[Gayan Soyza]

Does any body knows a software that tunes an amplifiers....

Its very hard to tune a amplifier at home (I dont have an oscilloscope & Even no place to buy one).I have made about 25 amplifiers STK 41xx,TDA 20xx,LA 4xxx,LM 1875...& Transistor......etc... Normally I Tunned by giving a Radio inpout (about 30mv) & adjusting the values in the pre amp until I hear a good quality sound.I know its not a quality way to check amplifiers like this....I heard there is a software which tunes amplifiers.. in a much decent way .

Can anybody give a named softwares for this?

I Hope my sound card giving a nice smooth output Its an Creative Live 5.1 output card........Planing to buy a new one Creative Sound Blaster X-Fi Elite Pro

Thanx

 

[Nigel Goodwin]

I don't have the faintest idea what you're on about?. Amplifiers don't need 'tuning', generally the only adjustment is the current through the output devices.

 

[HiTech]

RF power amps require tuning but you seem to be indicating audio amps. As for using those lousyl STK and LM/TDA audio chips, don't fret over "tuning" them for high quality audio. While they may have decent specifications, they aren't much of a match against using vacuum tubes and discrete semiconductors as "the choice" for quality audio amps.

There are special pick-up microphones used in conjunction with a laptop and software to generate a response curve, but often that's for speaker setup and room acoustics, not so much the amp. There are methods to calculate and design low distortion, hi fidelity amps, starting with class type, stage coupling, preferred capacitor types in key locations, shielding techniques, etc.

Using a "radio" input as you mention (i gather you are using a broadcast radio signal) is far from providing a good source for measurements and adjustment. Build yourself a white noise generator instead, or build an audio sweep generator from one of many simple kits cheaply available on the Internet. You'll have low & high freqs. and everything in between to better test an amplifier's response, if that's what you're trying to do. Using your ears in place of an oscilloscope is only as good as the speakers you are listening to! Speakers and room acoustics can be deceptive but a calibrated scope doesn't lie. You can save some money and bench space by using your computer to generate audio sweeps (plenty of applets found on the Internet that do it for free) and you can buy Winscope software to have your 'puter become a scope.

Now go get yourself some 12AX7 and KT88 tubes or some Motorola power mosfets and make yourself a real good amp!

 

[audioguru]

Two volume control knobs are confusing and allow the preamp or the power amp to clip.
"Tuning" the system is adjusting the volume of the preamp so its output doesn't clip. Then adjusting the volume of the power amplifiers so they don't clip.

If he is deaf then he needs clipping indicators, not a 'scope.
A more powerful amplifier would reduce the tendency of clipping for the power amp.

Tuning? Maybe his speakers are crappy and he is changing the EQ of the amplifier to try to compensate. But then he wouldn't need to tune it for each power amplifier.

Not enough power to compensate for his cheap speakers not having any bass? So the bass is "tuned" as high as possible before the speakers bottom out or the power amp clips. Some of his amps have hardly any power.
The speakers don't have enclosures? No bass.
The speakers are wired out-of-phase? No bass.

Vacuum tubes (valves)? Maybe he doesn't like their distortion and is "tuning" their levels so their distortion is minimum. The distortion of vacuum tubes is minimum when they are turned off.

 

[Hero999]

Also how do you know whether it's the speekers clipping or the amplifier.

 

[audioguru]

When a speaker bottoms out, it makes a noise completely different than an amplifier clipping. It is an intermittent loud popping sound. It is half-wave, so bass bottoming out is one octave below the music, like a very low pitched growl.
If you have cheap little 3" speakers then just look for the smoke.

 

[HiTech]

quality vacuum tube and mosfet amps have the lowest distortion specs around... hence why I mentioned KT88 or 6550... better yet... a matched pair of KT88. I happen to have two of them and not the Russian crap glass! They are worth big dollars. I use them in my 1958 McIntosh amp.

 

[audioguru]

I made a Heathkit vacuum tube amp in about 1962. It sounded great!(?) I took it to a McIntosh amp clinic to be tested and it had 12% distortion on one channel and half power with 22% distortion in the other channel. I replaced the tubes then it tested about 0.5%. The same problem next year, and again the next.

My solid state amp doesn't deteriorate and has 1/10th the distortion of my tube amp when it was healthy. The tube amp didn't damp the resonances of my speakers but the very high damping ratio of my solid state amp sure does.
.

 

[Nigel Goodwin]

quality vacuum tube and mosfet amps have the lowest distortion specs around...

You're living in your own little dream world! - valves have the highest distortion figures of any amplifier, by a LONG, LONG way - mosfets are OK though, and offer similar sorts of distortion figures to bipolar designs.

 

[Hero999]

Why anyone bothers with valve amps nowadays is beyond me.

 

[chemelec]

Why anyone bothers with valve amps nowadays is beyond me.

Tube amps Are Not about Quality Sound, They are about a PLEASING type of Distortion. Sound good to the ear, but not good on Electronic tests.

Especially true for Guitar amps.

 

[chemelec]

I don't have the faintest idea what you're on about?. Amplifiers don't need 'tuning', generally the only adjustment is the current through the output devices.

Possibly he is talking about Room Acoustics, With the use of a Pink Noise Generator / Equalizer Combination to attempt to get a True Frequency response?

 

[audioguru]

If you play FUZZ, BUZZ stuff on a good solid state amp then it hurts your ears.
If you play it on a distorted and muffled old tube amp then it sounds like an overdriven electric geetar.

 

[Hero999]

Tube amps Are Not about Quality Sound, They are about a PLEASING type of Distortion. Sound good to the ear, but not good on Electronic tests.

Especially true for Guitar amps.

Can't that be emulated somehow using filters and a non-linear device like a diode?

 

[audioguru]

The guy who invented the Carver amplifier modified his very good amp with EQ and diodes so that it sounded exactly the same (and just as bad) as name brand vacuum tube amps.

 

[Hero999]

I bet it was cheaper than a valve amp too.

 

[Nigel Goodwin]

Can't that be emulated somehow using filters and a non-linear device like a diode?

It can to a certain extent, but if you want a distorted valve sound, then use a valve amp!.

It's really bizarre what idiots will pay for it, you stick a single preamp valve in a guitar amp, plaster 'Valve Amp' on the front, and charge four or five times the price for it!. Quite a few such amps don't even have the valve connected!, just a resistor feeding the heater so it lights up!.

 

[Hero999]

That's even more of a waste of time if the valve isn't even being used!

 

[Nigel Goodwin]

That's even more of a waste of time if the valve isn't even being used!

Not a waste for the manufacturer! - add a valve, a socket, and a resistor, and sell your £100 preamp for £500!. Some others even use a valve strapped as two back to back diodes, just to give clipping, exactly as you would with two silicon diodes. Finally they can use the valve as an actual amplification stage, and overdrive it.

 

[audioguru]

If the guy needs to re-tune the EQ when he changes his amp because it causes the acoustics to change, then his room is way too small or his amps are way too big.