very confused

soundfreak1

I find the dampening rather important for bass slam. Can't explain in detail just anecdotally I have found it quite telling.

Realistic

Damping factor for the 1500a is 800 at 20hz. Damping factor for the 2250 is over 150 at 20hz. What is this and why is there such a big difference between the 2.

soundfreak1

The way I understand it is the higher rating effects the quickness of the bass, detail and (as I refer to it ) as slam. A low factor seems to result is slow muddy bass less detail and speed. Agreed their is some debate in this ( as far as importance) but just from my personal expierance amps I have owned or listened to extensively with lower factors were muddy in the bass and higher ratings were tighter and more detailed and had more bass "slam". That's just my expierance.

Realistic

Found some info on damping factor on google. Thanks for the replies you all have been great.

F1nut

The fact is the difference between a damping factor of 10 and 1000 is SO small that it has zero effect. I had an amp with a damping factor of 1000, had horrible bass control. Other amps I've had or have with damping factors in the low hundreds had/have excellent bass control.

F1nut

cfrizz wrote: »

And since both amps have plenty of both, he will be happy with either one.

How little you know.

leftwinger57

I'll just take away your confusion on what the 19" is referring to. It's the international standard of measurement for RACK Mounted Devices. For example my '80s vintage Adcom GFA-555 amplifier comes in 2 styles. Biggest draw would be the shelf placed model and mine is the rack face mounted model. Just about ALL pro-concert, touring and recording gear uses this standard. I'm showing examples of both styles. No affiliation w/ any of the listings. Wattage and current draw will be explained by others taking in with it speaker efficiency, length of runs, ohm's ratings etc..


http://www.ebay.com/itm/Adcom-GFA-555-II-Stereo-Power-Amplifier-200-watts-x-2-One-of-the-BEST-/272087457458?hash=item3f59ad1eb2:g:yR4AAOSw5IJWeLnp

http://www.ebay.com/itm/Mesa-Boogie-Simul-395-Guitar-Amplifier-With-Triaxis-Rack-Mount-/181965318210?hash=item2a5dfa6842:g:zTMAAOSwnGJWSp1B


http://www.ebay.com/itm/SAE-2400L-Rack-Mount-Stereo-Amplifier-Tested-Working-/262213598179?hash=item3d0d25fbe3:g:SjsAAOSwSHZWeK22

tonyb

The HCA series of Parasound amps, mainly the 1200 or 1500, are about the best bargains going for quality amplification for around 400 bucks. Maybe they aren't the prettiest, but their beauty comes in the way of current and sound.

As already stated, a high current amp is more desirable than a high wattage amp. Speakers run on current, more the better, especially if you have speakers with multiple drivers. During fast transients in your music or movies, the drivers of the speakers need to start and stop on a dime, or it will sound fat, slow, muddy. Current is what enables them to start and stop quickly while also bringing out more detail, better soundstaging, dynamics, and clearer sound at higher volumes. If any of that is of interest to you, get yourself a quality amp.

westmassguy

F1nut wrote: »

Watts mean squat, current is what counts.

Signature material right there

TennMan

When comparing amplifiers based on the one that has the most Current, how would you determine which one is best when choosing between, for example, a Parasound 1500a and an Adcom 555? Both are rated at ~200 Watts and have a 800 damping factor.

"High Current" now seems to be a selling feature by amp manufactures but they don't specify how much Current their amp has or how much it is capable of. Current is a measurement of the flow of electricity. If Current is more important than Watts when selecting an amp for sound quality (which I agree with) why is it not mentioned in amp specifications?

westmassguy

A good read on Damping Factor:
https://en.wikipedia.org/wiki/Damping_factor

soundfreak1

For my money I'd take the 1500 as I have more expierance with the HCA series. I will not argue damping factors as I'm not an engineer but I have had high and low and high has been better to my ears. The diff in the power between them to me is less important. Current diff is important.

tonyb

TennMan wrote: »

When comparing amplifiers based on the one that has the most Current, how would you determine which one is best when choosing between, for example, a Parasound 1500a and an Adcom 555? Both are rated at ~200 Watts and have a 800 damping factor.

"High Current" now seems to be a selling feature by amp manufactures but they don't specify how much Current their amp has or how much it is capable of. Current is a measurement of the flow of electricity. If Current is more important than Watts when selecting an amp for sound quality (which I agree with) why is it not mentioned in amp specifications?

Most will state it in "amperes peak to peak". The reason some don't state it is because that stat is pretty telling of a robust power supply. If you don't have that, why state it ? Won't be a selling point now would it.

People are sold on "watts" as the determining factor by the marketing gurus. That's why in AVR's all you see is a watts number, never an amperes number. That's because most receivers don't have a great deal of current......which is why we usually recommend adding amplifiers, depending on what you want to drive of course.

Some amps do have the current but simply don't state it. Mainly for reasons I already said, people are fixated on watts. Your average joe consumer has no idea what amperes peak to peak means anyway.

motorhead43026

The HCA-1500 is 60A peak per channel.

soundfreak1

motorhead43026 wrote: »

The HCA-1500 is 60A peak per channel.

One of the reasons I would chose it. Plus production dates are close to more "John curl" involvement in the design (I believe) don't know for sure how involved he was in the years 2000 on. Would have to do more research to confirm this admittedly.

TennMan

The title of this thread is a good one for the discussion of high current amps. The amplifier manufactures seem to all what to say their amps are "high current" and they add all the channels together when advertising their wattage. If you read the specs they tell you the watts for each channel but few of them (none of them I have seen myself) specify the amps they can deliver. I know we could probably calculate the amps ourselves based on other specs but we shouldn't have to that if they advertise the amp as a "high current" amp. They should prove it. Very confusing indeed if you want to select a truly high current amplifier.

transchris

There are so many deals out there for audiophiles...last week I bought a pair of like new rt2000i's for 180.00. The only thing wrong,if you want to call it that,if one speaker had a light brown wood veneer and the other is black....unbelievable! !! 5 months ago I went to Dallas and scored a pair of rta12's for 120.00...perfect condition. ...

Nightfall

B&K lists peak to peak amps, mine is 75.

soundfreak1

Considering most of us live with 20 amp circuit. Thank god they only draw it for milliseconds. Have had dimming of the lights though. LOL

dhart86

I had the HCA 1500 hooked up to my SDA 1c's and it was a perfect combo. I haven't heard the 2250. But from 1st hand experience, I say you can't go wrong with the 1500

BTW....we are hear / here to help you, so you don't need to apologize for what you don't know!

We all had to start at some point and I remember how helpful these guys were in getting my rig sounding better than I could have ever have imagined......

Great dudes on this forum and that is what this place is about

Good luck!

dhart86

BTW...like TonyB mentioned.a good price/value on the HCA 1500a is about $400-$475

Schurkey

TennMan wrote: »

When comparing amplifiers based on the one that has the most Current, how would you determine which one is best when choosing between, for example, a Parasound 1500a and an Adcom 555? Both are rated at ~200 Watts and have a 800 damping factor.

"High Current" now seems to be a selling feature by amp manufactures but they don't specify how much Current their amp has or how much it is capable of. Current is a measurement of the flow of electricity. If Current is more important than Watts when selecting an amp for sound quality (which I agree with) why is it not mentioned in amp specifications?

Because most amplifier manufacturers would be too embarrassed.

Of those that do mention an amperage spec, most of them are deceiving the public. If you see some crazy "ampere" spec, you can bet that the manufacturer is hoping you won't ask to see the test protocol.

motorhead43026 wrote: »

The HCA-1500 is 60A peak per channel.

Using what test protocol?

Nightfall wrote: »

B&K lists peak to peak amps, mine is 75.

Using what test protocol?

soundfreak1 wrote: »

Considering most of us live with 20 amp circuit.

"Most" of us live with 15-ampere circuits. 20 ampere circuits are not unheard of, but far less common than the plain ol' ordinary 15 ampere jobs.

soundfreak1 wrote: »

Thank god they only draw it for milliseconds.

You're onto less than half of the "dirty secrets" that the amplifier manufacturers don't want you to be thinking about..

I don't know the design elements of other amplifiers. I'll use my own "200-watt" amplifier as an example. My stereo amp is advertised as needing a 15-ampere circuit. The transformers (one for each channel) produce 70 volts on their secondary side, which is rectified and fed to the storage/filter caps. Forgetting for the moment about losses, this amp has 70 volt rails that supply the output transistors.

Now for some quick facts and light mathematics.

40 volts into an 8 ohm load will draw 5 amperes.
It takes 40 volts into an 8-ohm load to produce "200 watts" of output power.
40 volts / 8 ohms = 5 amperes
40 volts X 5 amperes = 200 watts

5 amps is a very, very long way from 60 or 75 claimed for other amplifiers.

This same amplifier puts out 400 watts into a 4-ohm load.
40 volts X 10 amperes = 400 watts
40 volts / 4 ohms = 10 amperes

10 amperes is still a long way from the 60 or 75 claimed for other amplifiers.

My "200 watt" amplifier will put out more than 200 watts into an 8-ohm load--but--the distortion goes up. It's not that the amplifier can't produce more than 200 watts, it's that the amplifier begins to lose control of itself, polluting the output signal with distortion as the power goes beyond it's rating.

Let's say we've disregarded distortion and amplifier longevity, were're running this amp flat-out at it's 70-volt maximum.

70 volts / 4 ohms = 17.5 amperes
70 volts X 17.5 amperes = 1,225 watts. This is so far beyond the amplifier rating as to be laughable. Moreover, the household circuit supplying this load probably can't maintain the nominal 120 volts, so at this point the power amp is fighting "brown-out" conditions at the transformer inlet, in addition to the output transistors being grossly overloaded on the other end.

And 17.5 amperes is still a damn long way from 60 or 75 claimed for other amplifiers.

(In the simplification above, I've deliberately failed to discuss the difference between peak vs. RMS voltages, and the effect of capacitance and inductance of a real speaker load on output current.)

At this point you're seeing a trend. The only mathematical way to get 60 or 75 amperes from an amplifier is to either have unusually high voltage by overdriving the input signal, and/or the load being driven must be unusually low impedance--lower than any reasonable speaker system. Either way will quickly overheat and damage the amplifier, so the testing protocol must be done quickly, before that heat can accumulate and raise temperatures.

THERE'S the three dirty secrets about claimed amperage output from an amplifier, and why the manufacturers will never disclose the test protocol involved in getting these astoundingly-high amperage figures that make such good ad copy.

1. The amplifier is run well beyond any reasonable measure of input signal voltage, so as to maximize the output voltage
2. The load impedance is ridiculously low--perhaps in the tenths of an ohm. Maybe LESS--remember that the manufacturers aren't telling us what the test protocol consists of!
3. To prevent damage to the amplifier, the testing is done so quickly (the tiniest fraction of a second) as to be not musically significant.

In short, wildass claims for amperage are a big, fat, lie that the FTC should be taking action on, because they're so far out of the normal operation of the amplifier as to be "science fiction".

When folks ask how much amperage my amplifier will put out, the manufacturer asked "How much do you want it to put out? We can design a test protocol to get you any number you ask for." This amplifier has it's power rails protected by a 10-amp fuse on each positive rail, and a 10-amp fuse on each negative rail. Therefore, within limits of the house-current supply, storage-capacitor size, and output-transistor heat sinking, it will throw 20 amperes per channel. It will also sound good driving ~"1-ohm" speakers, it's not known for being short of output current!

Are you sorry you asked?

RandyCroissant

I like that Schurkey, that's good reading. And it makes sense, not to mention that putting a massive 60 or 70 amp load like that on your speakers even for a millisecond would probably fry them. Burn da dang house down.

soundfreak1

Try sitting in a say 20x20 room 3 feet away from a pair of speakers purring along a 1 watt continuous.

TennMan

Schurkey wrote: »

TennMan wrote: »

When comparing amplifiers based on the one that has the most Current, how would you determine which one is best when choosing between, for example, a Parasound 1500a and an Adcom 555? Both are rated at ~200 Watts and have a 800 damping factor.

"High Current" now seems to be a selling feature by amp manufactures but they don't specify how much Current their amp has or how much it is capable of. Current is a measurement of the flow of electricity. If Current is more important than Watts when selecting an amp for sound quality (which I agree with) why is it not mentioned in amp specifications?

Are you sorry you asked?

Not at all. I enjoyed reading it.

Realistic

There are 2 1500s on ebay one for 575 plus shipping, this one has no feet could these be obtained new or used? The other is a bid deal, there is one more also but that one is 875 plus shipping. I am a little nervous buying on ebay but im sure all will be fine. dhart86 thanks, its nice to have a place to talk to people who are willing to help. Everyone who has replied to this post has been a great help to me. I am not a audiophile like all of you here but I do enjoy my music very much. I am sold on buying the 1500 I am just shitting myself thinking about buying the amp it does not work and now I have a cool black box I can put in the trunk of my car for winter traction lol. Thanks a lot to all of you. Bob.

Schurkey

RandyCroissant wrote: »

I like that Schurkey, that's good reading. And it makes sense, not to mention that putting a massive 60 or 70 amp load like that on your speakers even for a millisecond would probably fry them. Burn da dang house down.

Let us, for the moment, consider putting 70 amperes into a "4-ohm" nominal speaker.
280 volts / 4 ohms = 70 amperes.
280 volts X 70 amperes = 19,600 watts.

Yep, I think the voice-coils might be in danger. That, and your eardrums would probably slam together in the middle of your head.

Nightfall

Could 70 amps be drawn from the reserve in the caps, if even for an instant? Maybe that is how they are claiming it possible?

F1nut

Further insight.

http://www.meyersound.com/support/papers/amp_power.htm

Realistic

I put in a bid so now its a waiting game I guess. I have a feeling that these amps will go for more than I have but I am going to try anyway. The prices have gone up or people are sure they can sell this stuff for whatever price they want because someone with a bigger budget that wants one will buy them, not good for me. I will keep you posted. Thanks again for all the help and guidance.