Oldies Integrated Amps

[Desmond82]

Hi, I had 2 oldies different types of Stereo Integrated Amplifier, a TEAC BX-500 and a KENWOOD KA-50. Did anyone know what is the Class category (A,AB,B or C) of both amps? And how well is their audio quality?

 

[Seth=L]

Hi, I had 2 oldies different types of Stereo Integrated Amplifier, a TEAC BX-500 and a KENWOOD KA-50. Did anyone know what is the Class category (A,AB,B or C) of both amps? And how well is their audio quality?

They are both most likely some derivitive of Class A/B. I would say both will be decent, just don't expect fantastic results with very high end speakers.

 

[fmw]

Why not? High end speakers don't have any particular requirements just because they are high end. I've found that many of the toughest speakers to drive are in the pro audio world and usually fairly inexpensive. I do agree that the integrateds will most likely have Class AB amplification.

 

[Joe Schmoe]

I just gave away an old Carver integrated. The new Cambridge Audio integrated I replaced it with sounds vastly better. Lower distortion, more detail, better imaging, better bass control, and lower noise floor.

 

[gus6464]

I just gave away an old Carver integrated. The new Cambridge Audio integrated I replaced it with sounds vastly better. Lower distortion, more detail, better imaging, better bass control, and lower noise floor.

Which Cambridge model did you get?

 

[Desmond82]

Does it says class AB is 1 grade lower than Class A? Cux I do know that Class A amp has high heat dissipation where it effiency is about 30%. So do Class AB amps?

 

[fmw]

Does it says class AB is 1 grade lower than Class A? Cux I do know that Class A amp has high heat dissipation where it effiency is about 30%. So do Class AB amps?

A class A amp by definition will have lower distortion. An AB amp will still have inaudible distortion but higher efficiency. In this day and age, there would be no audible difference because of this. There is no reason to make a class A amplifier at all like there was many years ago.

These days, efficiency has been raised to new heights still with inaudible distortion with switching amps like classes D, G and H. The H amps even modulate the rail voltage based on the power draw so the output biasing changes constantly. Extrememly efficient, still inaudible distortion. AB amps are now becoming as rare as class A amps.

 

[Desmond82]

A class A amp by definition will have lower distortion. An AB amp will still have inaudible distortion but higher efficiency. In this day and age, there would be no audible difference because of this. There is no reason to make a class A amplifier at all like there was many years ago.

These days, efficiency has been raised to new heights still with inaudible distortion with switching amps like classes D, G and H. The H amps even modulate the rail voltage based on the power draw so the output biasing changes constantly. Extrememly efficient, still inaudible distortion. AB amps are now becoming as rare as class A amps.

Anyway, Classes D, G & H nowadays used in which type of amplifier? A/V receiver? Does it provide less audible distortion than class AB?

 

[Seth=L]

Why not? High end speakers don't have any particular requirements just because they are high end. I've found that many of the toughest speakers to drive are in the pro audio world and usually fairly inexpensive. I do agree that the integrateds will most likely have Class AB amplification.

The noise floor is likely to be higher and those older integrated amplifiers are probably most comfortable with 6 ohm to 8 ohm loads. I wouldn't put inefficient hard load speakers with those amplifiers.

 

[Seth=L]

Anyway, Classes D, G & H nowadays used in which type of amplifier? A/V receiver? Does it provide less audible distortion than class AB?

Most receivers still use Class A/B. Some smaller receivers and home theater in a box systems use class D amplifiers. Some examples of companies that use Class D primarily are JVC and Panasonic for their receivers, most others stick with Class A/B. Class H is a derivitive of Class A/B that is more efficient but maintains the heft of Class A/B amplifiers (someone correct me if I am wrong on that). Class A amplifiers can have lower distortion, but tube amplifiers typically don't (not because they can't, but because the distortion on tube amplifiers is a desired result for that "warm" sound they have). Class A transistor amplifiers are typically very large and exibit massive heatsinks to displace the massive amounts of heat they produce. Class A amplifiers are typically very expensive, tubes and transistors.

 

[fmw]

Anyway, Classes D, G & H nowadays used in which type of amplifier? A/V receiver? Does it provide less audible distortion than class AB?

No, they produce higher distortion but I think you are missing the point. The distortion is low enough to be inaudible in all of them. A good example of this type of amplifier is the Pioneer Elite A/V receivers such as my VSX-92THX. It runs as cool as a cucumber thanks to the efficiency of the amps and sounds just like every other amp with inaudible distortion and a flat frequency response.

The advantage of switching amps is that they are quite a bit more efficient. That provides a longer life thanks to less heat, less expensive manufacture since it doesn't require as hefty a power supply or as much heat dissipation, and usually more output power since it is easier and less expensive to achieve. The downside is distortion but the distortion is inaudible anyway. That's why you see such a rapid change to this type of design.

Just a few years ago switching amps produced audible distortion and you saw them mostly in applications like subwoofer amps. But they've overcome that problem. There is much to gain with switching amps now and not much to lose.

 

[fmw]

The noise floor is likely to be higher and those older integrated amplifiers are probably most comfortable with 6 ohm to 8 ohm loads. I wouldn't put inefficient hard load speakers with those amplifiers.

Neither would I but my point was that all high end speakers are not necessarily inefficent and designed with a low nominal impedance. A good example are the B&W.

 

[Desmond82]

No, they produce higher distortion but I think you are missing the point. The distortion is low enough to be inaudible in all of them. A good example of this type of amplifier is the Pioneer Elite A/V receivers such as my VSX-92THX. It runs as cool as a cucumber thanks to the efficiency of the amps and sounds just like every other amp with inaudible distortion and a flat frequency response.

The advantage of switching amps is that they are quite a bit more efficient. That provides a longer life thanks to less heat, less expensive manufacture since it doesn't require as hefty a power supply or as much heat dissipation, and usually more output power since it is easier and less expensive to achieve. The downside is distortion but the distortion is inaudible anyway. That's why you see such a rapid change to this type of design.

Just a few years ago switching amps produced audible distortion and you saw them mostly in applications like subwoofer amps. But they've overcome that problem. There is much to gain with switching amps now and not much to lose.

Oh ok I get your point. But as compare to oldies amps is it better than the modern amps? Anyway have you heard before KLH speakers?

 

[fmw]

No, I don't think old amps are better than modern ones. Older ones were made with discreet components while modern ones use integrated circuits but the results are about the same sonically. One disadvantage to using old equipment is that the discreet components from which they were made can be aged and fail.

When KLH started in the 1960's they were a high end audio manufacturer and made first class speaker systems. They soon switched in the 1970's to the mass market. The old originals are dead, suffering from rotted surround foam. The younger ones are cheaply made. Personally, I wouldn't fool with them.

 

[Desmond82]

No, I don't think old amps are better than modern ones. Older ones were made with discreet components while modern ones use integrated circuits but the results are about the same sonically. One disadvantage to using old equipment is that the discreet components from which they were made can be aged and fail.

When KLH started in the 1960's they were a high end audio manufacturer and made first class speaker systems. They soon switched in the 1970's to the mass market. The old originals are dead, suffering from rotted surround foam. The younger ones are cheaply made. Personally, I wouldn't fool with them.

As my prediction amplifiers circuitry built with ICs may not serve as good as discrete components right? But the disadvantages is it may be failed due to aging and affect with electromagnetic interefernce easily.(correct me if i'm wrong) By the way, how do you think of DENON PMA1500R which is 8 yrs ago model?

 

[B3Nut]

An advantage of discrete transistors is the ability to use multiple pairs to increase the amount of current they can safely pass into the load. This is useful for amplifiers that need to drive low-impedance loads (the Onk 805 is one of the few AVR's to use doubled pairs of output transistors, this practice is common in standalone power amps with two or more pairs per channel.) IC power amps can offer theoretically superior thermal stability however, since the output devices and bias circuits share a common thermal substrate.

Newer units like the VSX-92 don't appear to be switching designs (I would be surprised if it was, their "Direct Energy" moniker appears to be yet another cute name for a direct-coupled power amp stage like they've been making for over 30 years...were they using switching amps they'd have written no end of press blurbs to trumpet them...wait until they start marketing their upcoming flagship!) The Pioneer Elites are superlative units, to be sure...I'd take one in a minute. Most of their line from the 1017 up appear from gazing under the lid to be standard class AB bipolar designs (I wish they had schematics on their website!), though some recent Pioneers have used MOSFET output transistors. Pioneer tends to run their output stages conservatively to keep heat down and increase dependability...they've been that way since the 70's. The 917 on down use their IC power amps, they work fine but are limited in the amount of current they can pass (standard for the breed.) They do perform better than they have a right to on the bench. The IC amps are typically AB or B. A class AB amplifier can certainly run cool or run hot, depending on where the idle current is set, or if it's in spec. They shouldn't idle too hot, however.

Class AB is far from rare, it is still the norm rather than the exception. Pioneer will be introducing switching amps to their receiver line with their upcoming flagship which uses ICEPower modules. It is a beast of a receiver, bigger than the Denon 5805. 10 channels of ICEPower amplification. Did I mention that it was a beast?

Denon has made solid integrateds for years, I wouldn't refuse a well-cared-for older unit, especially if it can be had for cheap. Then again, I've long had a soft spot for vintage gear, I love the way a lot of that equipment was built. They're fun to work on, too.

 

[fmw]

As my prediction amplifiers circuitry built with ICs may not serve as good as discrete components right? But the disadvantages is it may be failed due to aging and affect with electromagnetic interefernce easily.(correct me if i'm wrong) By the way, how do you think of DENON PMA1500R which is 8 yrs ago model?

I consider 8 years old to be a modern amp. I think we've been talking about 25 and 30 year old amps.

 

[fmw]

An advantage of discrete transistors is the ability to use multiple pairs to increase the amount of current they can safely pass into the load. This is useful for amplifiers that need to drive low-impedance loads (the Onk 805 is one of the few AVR's to use doubled pairs of output transistors, this practice is common in standalone power amps with two or more pairs per channel.) IC power amps can offer theoretically superior thermal stability however, since the output devices and bias circuits share a common thermal substrate.

Newer units like the VSX-92 don't appear to be switching designs (I would be surprised if it was, their "Direct Energy" moniker appears to be yet another cute name for a direct-coupled power amp stage like they've been making for over 30 years...were they using switching amps they'd have written no end of press blurbs to trumpet them...wait until they start marketing their upcoming flagship!) The Pioneer Elites are superlative units, to be sure...I'd take one in a minute. Most of their line from the 1017 up appear from gazing under the lid to be standard class AB bipolar designs (I wish they had schematics on their website!), though some recent Pioneers have used MOSFET output transistors. Pioneer tends to run their output stages conservatively to keep heat down and increase dependability...they've been that way since the 70's. The 917 on down use their IC power amps, they work fine but are limited in the amount of current they can pass (standard for the breed.) They do perform better than they have a right to on the bench. The IC amps are typically AB or B. A class AB amplifier can certainly run cool or run hot, depending on where the idle current is set, or if it's in spec. They shouldn't idle too hot, however.

Class AB is far from rare, it is still the norm rather than the exception. Pioneer will be introducing switching amps to their receiver line with their upcoming flagship which uses ICEPower modules. It is a beast of a receiver, bigger than the Denon 5805. 10 channels of ICEPower amplification. Did I mention that it was a beast?

Denon has made solid integrateds for years, I wouldn't refuse a well-cared-for older unit, especially if it can be had for cheap. Then again, I've long had a soft spot for vintage gear, I love the way a lot of that equipment was built. They're fun to work on, too.

You are probably right. The reason I believed they are switching amps is that they generate almost no heat to the top surface of the case. I owned a 1017 once and it was fairly cool-running but not like the 92. The 92 is barely above room temperature when in use - certainly cooler than the temperature of the skin on my arm. The amps are therefore certainly very efficient and, from my experience, moreso than any AB amp I've ever encountered. If it is an AB design then others should emulate it. Keeping the temp down can only help the longevity of the product.

 

[B3Nut]

AB amps can indeed run quite cool at idle depending on how it is designed. I have noticed perusing the latest Onkyos on the shelves that an inordinate amount of heat seems to be produced by the DSP board more than the amplifiers. Apparently the "popping" issue that plagued the 605 was related to an overheating DSP chip...any processor chip will begin to produce errors if it gets too hot, this is what causes your PC to lock up if the processor starts to overheat. It makes me wonder if they're trying to overclock their DSP chips... Why didn't they just go all the way and add watercooling and neon lights...

 

[Seth=L]

The IC in my Teac stays super cool, I like it a lot. Maybe the TX-SR805 and up produce so much heat because of their configuration.