What's a 'DC integrated amplifier"?

[davidro]

G'day all

I couldn't find the answer on googling so I holler here. What's a 'DC integrated amplifier" and how is it different from other amplifiers? Or is it different at all? My Teac amp is 'High Speed DC Integrated Amplifier". Fancy. But what's that supposed to mean? :scratch2:

 

[Hyperion]

High speed = Largely marketing hype - from the days when 'slew rate' was all the rage.

DC= Direct Coupled = using no capacitors in the audio path.

Integrated = Power amplifier and Pre-amplifier 'integrated' together in one box.

 

[catman]

G'day mate, I presume that 'DC' refers to 'direct coupled' amplifier stages (no capacitors), which was all the rage a good while back.

They can work extremely well, but the big hassle is trying to fault find a DC coupled amp. Not easy. Regards, Felix aka catman.

 

[davidro]

Using no capacitor - implying 'purer' signal transmission?

 

[Watthour]

That's the implication, and it might be valid if you were a retriever or spaniel and had any kind of aural acuity above 18KHz. If that were the case, however, you'd have a pretty tough time connecting the speaker terminals.

It's what's sometimes referred to as an "impractical truism" since it is technically correct but practically meaningless. It's akin to comparing the "500HP" from a turboed Honda V-6 to a 535 Mk IV. Sure, it's 500HP, but at 45 ft/lb of torque it's pretty meaningless since it won't last long at 12K RPM. 500HP @ 500 ft/lb is a lot more practical, just like capacitance-coupled amp stages.

 

[whoaru99]

It's what's sometimes referred to as an "impractical truism" since it is technically correct but practically meaningless. It's akin to comparing the "500HP" from a turboed Honda V-6 to a 535 Mk IV. Sure, it's 500HP, but at 45 ft/lb of torque it's pretty meaningless since it won't last long at 12K RPM. 500HP @ 500 ft/lb is a lot more practical, just like capacitance-coupled amp stages.

Actually, the Honda would be 219 ft/lb of torque @ 12k.

 

[Oilmaster]

Using no capacitor - implying 'purer' signal transmission?

Yes, but the disadvantage is that the two stages being direct connected must have/maintain identical DC voltage levels, and adequate impedance matching, which imposes often a more complex circuitry to keep things together as opposed to capacitor-coupled design. Thermal effects in individual components offsetting DC levels to call one. In the end, both design topologies have their plusses and minus.

 

[davidro]

Yes, but the disadvantage is that the two stages being direct connected must have/maintain identical DC voltage levels, and adequate impedance matching, which imposes often a more complex circuitry to keep things together as opposed to capacitor-coupled design. Thermal effects in individual components offsetting DC levels to call one. In the end, both design topologies have their plusses and minus.

Does that mean it could only drive one type of impedance? My Teac is supposed to do 55wpc at 8 ohm but there's no info on its output at 4 ohm.

 

[EchoWars]

When a mfgr. says 'DC Amplifier', it very very rarely means zero caps in the signal path...that goes triple for an integrated amp with lots of preamp functions to deal with. What it does generally mean is that the output stage of the power amp is powered by +/- DC supplies and is sans a big DC blocking capacitor at the output. The 'DC Amplifier' looks nice in front panel lettering, but it hasn't exactly been a 'feature' in a power amplifier since 1972.

Does that mean it could only drive one type of impedance? My Teac is supposed to do 55wpc at 8 ohm but there's no info on its output at 4 ohm.

It should be able to power most 4 ohm speakers just fine.

 

[SoCal Sam]

When a mfgr. says 'DC Amplifier', it very very rarely means zero caps in the signal path...that goes triple for an integrated amp with lots of preamp functions to deal with. What it does generally mean is that the output stage of the power amp is powered by +/- DC supplies and is sans a big DC blocking capacitor at the output. The 'DC Amplifier' looks nice in front panel lettering, but it hasn't exactly been a 'feature' in a power amplifier since 1972.It should be able to power most 4 ohm speakers just fine.

EW, so taking this one step further, is this true:

DC amps are complimentary.
Cap coupled are not.

??:scratch2::scratch2:

 

[davidro]

It should be able to power most 4 ohm speakers just fine.

Thanks. Is it possible to guess the 4 ohm output?

 

[grateful]

In the purest sense the DC amplifier will amplify down to DC or 0 HZ. ImHo they sounded great but tended to fail with a lot of semiconductor damage. The principal was discontinued because of the high warranty service rates to manufacturers.

 

[sax6]

Really liked this thread b'cause i have so many , so-called dc int amp
and i like electronic

thanks

 

[bman22]

Thanks. Is it possible to guess the 4 ohm output?

From a purely mathematical standpoint, if it can do 55wpc into 8 ohms, it can do 110wpc into 4. Half the impedance, double the power. I highly suggest you don't ever try pushing it that hard into four ohms though, as most likely the output devices won't be able to widthstand that.

 

[steerpike2]

When a mfgr. says 'DC Amplifier', it very very rarely means zero caps in the signal path...that goes triple for an integrated amp with lots of preamp functions to deal with. What it does generally mean is that the output stage of the power amp is powered by +/- DC supplies and is sans a big DC blocking capacitor at the output.

^^^ Agreed with that, in most cases. There are some esoteric expensive amps that are true DC, but generally in 80s-onward far-east amps, it's just the output stage that's DC.

EW, so taking this one step further, is this true:
DC amps are complimentary.
Cap coupled are not.

No, you can build a fully complementary amp, and run it from a single-ended power supply (0...+50V). It will then idle at +25V above ground, and need an output capacitor. Its internal 'ground reference' would likely be a 50/50 voltage divider across the power supply.

 

[guiller]

My Teac is supposed to do 55wpc at 8 ohm but there's no info on its output at 4 ohm.

What is the model number?

 

[ghamilton]

My Sansui AU-919 & Kenwood L-05m amps should be true DC all the way. No problems except maintainance. Very reliable! The purest sound. I love DC with bi-polar outputs.:yes:

 

[EchoWars]

The 919, strictly speaking, is not, since it includes a preamp section with lots 'O caps. The pwr amp is all DC.

The L-05M, being only a power amplifier, uses a DC coupled FET input (similar to the amp section of the 919), and has no caps in the signal path.

 

[ouimetnick]

So there is a regular amplifier, then this,and also one that has caps on the outputs, so you can't measure DC offset in the regular way?

 

[davidro]

What is the model number?

It's BX-550. A strenuous googling didn't reveal the full specs!