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David Hafler DH-220 versus Modern Threater System

brainless

brainless

Member
Hello all. I'm very much a typical off-the-shelf home audio person, but trying to learn a few more things to improve my system. I have a basic Samsung HT-D5300 home theater system. Over the years I have acquired various Cerwin Vega speakers that have replaced the little plastic ones that came with the system. To my ears it has been a vast improvement. Recently I had the opportunity to purchase a DH-220 stereo power amp. It needed minor repair so I got a really good deal. Connecting it to my turntable via RIAA preamp I was absolutely stunned at the response and raw power it delivered. It made the Samsung sound very weak by comparison.

Here's the question: How is it that the DH-220 delivers 115W per channel, the Samsung 165W per channel, yet the DH-220 far out performs in shear power and sound? Also curious why the Samsung states 70W/120VAC (with multiple 165W outputs for 5.1 surround) and the DH-220 states 840W/120VAC, yet the Samsung specs imply more power to the speakers and sounds weaker? Is this related to the DH being linear power supply and all analog while the Samsung is switching amps and power supply?

Any help in understanding this would be greatly appreciated. Please pardon me if I used any incorrect terms in my descriptions.
 
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Stereo 2-channel gear must meet tougher standards for power compared to multi channel devices and the Hafler was built in a great period for home stereo.

Kinda like Clydesdale horsepower vs. Shetland pony horsepower.
 
There is more than one way to arrive at a power output figure that a manufacturer can claim for marketing purposes. Proclaiming the most amount of power for the least amount of money being the objective.

That Hafler is rated for the least amount of power it will produce at any audible frequency with both channels driven at the same time. It takes a large transformer and higher internal voltages to accomplish that therefore the higher 120V consumption of 840W.

Such a Samsung device is rated a lot more "optimistically". Like on a very good day, with a tail wind and under more closely controlled conditions. Measuring only one channel at a time and at a single certain frequency - one that is easy to reproduce.
 
This should be enough to teach you not to buy on specs, or rely on them for describing sound quality. :)

LOTS of AK'ers are overly enamored with specifications. Some specs are good for determining compatibility or suitability for a purpose, but most do not correlate with sound quality, unfortunately.

The Hafler has had an excellent reputation for 40 years. Of course buying by reputation has its pitfalls too, but only the snootiest audiophiles would diss the Hafler. And they would be wrong.

Congratulations!
 
Thank you very much for the informative replies! This is a very interesting forum. The output impedance of the DH220 is 8 ohms and matches the Cerwin-Vega AT-12 speakers. The Samsung outputs are 3 ohms therefore not a good match for the AT-12's. I probably should have noticed this important difference right way, but I'm very new to the realm of quality audio equipment. I was so surprised that the dusty old DH220 worked I didn't take the time to look at the basic issue of impedance. I still don't understand how the Samsung can be line power rated at 120VAC 70W and yet claim to drive 5.1 channels at over 150W each. I suppose they might be stating based on instantaneous output power versus continuous? Thanks again for the help!
 
The output impedance of the Hafler is not 8 Ohms. Power amplifiers are not rated that way. It is rated to deliver a specific amount of power into a given load. There is no such thing as an 8 Ohm or a 4 Ohm or a 3 Ohm amplifier. Please note, better amplifiers will usually work into lower impedance loads. All of them will work into an 8 Ohm load.
Here's a link to the manual. It gives all the specs.
https://hafler.com/pdf/archive/DH-220_amp_man.pdf
 
@JoeESP9 , I think the Samsung if it has a speaker at 3Ω and that is what the amp is looking for it is more like car stereo gear, looking to get big numbers from a low impedance speaker. This leads me to believe it struggles at 8Ω, not knowing if there is a real rating for the unit. Here are screenshots of the amp and speaker specs, both 3Ω. One more tidbit this unit weighs 7.7 pounds.
 

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According to the Samsung HT-D5300 specs, the total power output of the six channels (5.1) just happens to add up to exactly 1000 watts, a rather suspicious circumstance. A kilowatt amplifier would require a humongous heat sink(s). Hafler amps did have really big heat sinks and really did deliver the claimed power under FTC mandated measurement requirements. There are numerous ways around FTC regulations about power ratings, including outright lying. My very strong suspicion is that this is the case here.

I am reminded of the outrageous MIPS ratings of PCs years back, which were simply mathematical fictions with no relation to the real world. It sounds like the same sort of thing applies here.
 
BTW, welcome to AK! :)

The old FTC regulations for amplifier power claims, enacted in 1974 I believe, were quite strict. The claim had to be for continuous power, not "peak" power or "music power". The claim had to include a bandwidth (usually 20 Hz to 20,000 Hz (20 kHz)) over which the rating held true. It had to include a THD (total harmonic distortion) figure for the claimed power throughout the claimed bandwidth. It had to include the output load in ohms that the test was performed with. The rating had to be per channel, with all channels driven. Perhaps most telling, the equipment had to be 'pre-conditioned' by running it at 1/3 of the claimed power for one hour before the test was performed. That last requirement alone made robust power supplies and sufficient heat dissipation essential to a successful design.

These rules have been loosened considerably in the years since, as multi-channel home theatre systems, powered subwoofers, and active (powered) speaker designs became common. The rules have become much less strict. In particular, the pre-conditioning requirement has been lowered to 1/8 the rated power, from 1/3 the rated power. The old pre-conditioning requirement was impossible to meet with skimpy designs, and is the main reason why older equipment had bigger power transformers, better heat sinks, and weighed so much. There are those who believe that the new, looser requirements allow for more efficient design, but many traditional stereo manufacturers still rate their products using the old rules.

Specs never were any good for estimating sound quality, and now they are much less useful even for just comparing output power capabilities.

Oh, well. :(
 
Imprecise said:
A kilowatt amplifier would require a humongous heat sink(s).
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If it's Class D, it could achieve kilowatt output levels with minimal heat sinking, because Class D is over 90% efficient. I.e., only 10% of the energy from the power socket turns into waste heat that needs to be dissipated via heat sinks, the rest makes the speakers move.

Class AB requires heavy heat sinks because it's only 75% or less efficient. Class A requires even more heat sinking because it's less than 30% efficient. In other words, 70% or more of the power from the wall plug is wasted as heat rather than producing sound.
 
Blue Shadow said:
@JoeESP9 , I think the Samsung if it has a speaker at 3Ω and that is what the amp is looking for it is more like car stereo gear, looking to get big numbers from a low impedance speaker. This leads me to believe it struggles at 8Ω, not knowing if there is a real rating for the unit. Here are screenshots of the amp and speaker specs, both 3Ω. One more tidbit this unit weighs 7.7 pounds.
Click to expand...

Sorry, it doesn't work that way. An amplifiers output impedance has very little to do with the load it's driving. They are related but not in the way you're thinking.

Check this link from PS Audio. It's a very good explanation without being overly technical.
.https://www.psaudio.com/pauls-posts/output-impedance/
 
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The output impedance is not listed. That is the power into a 3 ohm load. That is what I'm getting at. This was a matched set for cheap and now the OP has a real amplifier. He is on the road to great things in an real stereo system.
 
Imprecise said:
According to the Samsung HT-D5300 specs, the total power output of the six channels (5.1) just happens to add up to exactly 1000 watts, a rather suspicious circumstance. A kilowatt amplifier would require a humongous heat sink(s). Hafler amps did have really big heat sinks and really did deliver the claimed power under FTC mandated measurement requirements. There are numerous ways around FTC regulations about power ratings, including outright lying. My very strong suspicion is that this is the case here.

I am reminded of the outrageous MIPS ratings of PCs years back, which were simply mathematical fictions with no relation to the real world. It sounds like the same sort of thing applies here.
Click to expand...

Multi-channel receivers and amplifiers do not have to conform to the FTC standards. That's why most HT receivers have such inflated power ratings. Many of their ratings might as well be ILS (if lightning strikes).
 
Thank you for the replies. At this point I am totally clueless about the technology, just a typical department store shopper. I should probably just lurk for awhile and try to learn the basics before peppering everyone with questions. I'm making the typical newbie mistake. The reason I thought that the impedance difference might be a factor in my situation (i.e. Samsung vs DH-220 perceived performance difference) was due to a statement in the DH-220 manual page 4: "If you have 4 ohm speakers, the maximum cable length for best results is halved." That made me think that mismatched speaker impedance could effect actual volume and sound quality. I really don't have a technical background so I'm way out of my league here. I need to do some homework as I'm probably coming across as a total dumb a*s.
 
That passage in the Hafler manual refers to the maximum length of speaker cables. The statement reflects standard diameter/gauge versus length. Use at least 16 gauge wire for any speaker cable under 20' or so and it's a non issue.
 
JoeESP9 said:
That passage in the Hafler manual refers to the maximum length of speaker cables. The statement reflects standard diameter/gauge versus length. Use at least 16 gauge wire for any speaker cable under 20' or so and it's a non issue.
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Thank you. That makes sense. My brain is the weakest link in in my audio system! What threw me were the statements "Standard 18 gauge lamp cord is satisfactory for distances up to 30 feet for 8 ohm speaker." followed by the statement "If you have 4 ohm speakers, the maximum cable length for best results is halved" I interpreted that to mean that there was a load difference between the 8 ohm and 4 ohm speaker necessitating a halving the distance for the 4 ohm (i.e. half the impedance) load to maintain performance. My cognitive abilities aren't what they used to be. I'm way out of my league here with the technical issues. It's going to be too steep a learning curve for me. I'm going stick with the Samsung and probably sell the DH-220 on eBay. Seems to work really well. It will go to someone who will understand the applications and make better use of it than I ever would. Thank you again for the tips and info.
 
brainless said:
Thank you. That makes sense. My brain is the weakest link in in my audio system! What threw me were the statements "Standard 18 gauge lamp cord is satisfactory for distances up to 30 feet for 8 ohm speaker." followed by the statement "If you have 4 ohm speakers, the maximum cable length for best results is halved" I interpreted that to mean that there was a load difference between the 8 ohm and 4 ohm speaker necessitating a halving the distance for the 4 ohm (i.e. half the impedance) load to maintain performance. My cognitive abilities aren't what they used to be. I'm way out of my league here with the technical issues. It's going to be too steep a learning curve for me. I'm going stick with the Samsung and probably sell the DH-220 on eBay. Seems to work really well. It will go to someone who will understand the applications and make better use of it than I ever would. Thank you again for the tips and info.
Click to expand...

Don't sell the Hafler it's the best peice in your system. If you do, 2 years from now you will be kicking yourself. Set it to the side and take the time to learn about putting a system together. Where are you located? I am sure you can find someone to help you with this.
 
brainless said:
Thank you. That makes sense. My brain is the weakest link in in my audio system! What threw me were the statements "Standard 18 gauge lamp cord is satisfactory for distances up to 30 feet for 8 ohm speaker." followed by the statement "If you have 4 ohm speakers, the maximum cable length for best results is halved" I interpreted that to mean that there was a load difference between the 8 ohm and 4 ohm speaker necessitating a halving the distance for the 4 ohm (i.e. half the impedance) load to maintain performance. My cognitive abilities aren't what they used to be. I'm way out of my league here with the technical issues. It's going to be too steep a learning curve for me. I'm going stick with the Samsung and probably sell the DH-220 on eBay. Seems to work really well. It will go to someone who will understand the applications and make better use of it than I ever would. Thank you again for the tips and info.
Click to expand...
First off welcome to AK a place where there’s vast knowledge from some pretty good people from all over the world so your in good hands here . Secondly, stop thinking so deep into this and sit back and enjoy the music , you can learn on the way . No need to put yourself out just because you don’t understand something, none of us here started out knowing everything there was about stereos and we still don’t know it all but we learn as we go along , so no use in selling yourself short for lack of knowledge.

Audiofreak71
 
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You are well ahead of many here. Hang in there, you don't need special knowledge to put a fine system together.

I recommend you start a thread and tell us what you want to do as far as a stereo goes. Their are many here that use to sell to folks who had no clue and they went away with a nice stereo the enjoyed. You bought the Hafler for a reason, let us know what you thought you might do and folks can recommend a way to get where you want to go. Drop your location because folks will look at your local CL and recommend stuff. Do you want a nice stereo?
 
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