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Our FAQ's page is based on actual conversations that had taken place over a period of time between a very curious customer and Dan Banquer, Designer and Engineer of R.E. Designs. We hope this will help you separate myth from reality and also give you an understanding of what R.E. Designs truly represents. For any questions that we have not answered here for you, please call or send us an email. We'll be happy to answer all your questions!

You may also visit our audio forum for lively debate or try to stump Dan with your technical questions... click here.

Dave: Your power amp specs give your Total Harmonic Distortion (THD) at 0.1% which is pretty high for a solid state amp. Yet I don't hear that usual aggravating solid state distortion.

Dan: Your're right, it is high compared to most solid state amps but there is a reason you can't hear the distortion. The harmonic distortion in the LNPA 150 is all second order distortion!

Years ago a number of papers were written on human hearing and harmonic distortion. What they found was that the human ear is very insensitive to harmonic distortion that is close to the main signal, and increases in sensitivity to harmonic distortion further away from the main signal. The second harmonic, which is an octave away from the main signal, is the hardest to hear, especially when you are driving a loudspeaker.

The best estimates that I can give you is that we can detect somewhere between 1% and 3% of second order harmonic distortion. Which is why you can't hear it. If the sum total distortions were farther away from the main signal you would be able to hear it. Some solid state designs can have pretty low distortion but they can get to be aggravating after awhile. That's because the distortion generated by the amp is further away from the main signal where the ear is more sensitive.

Dave: Didn't The Audio Critic also say you had slewing induced distortion too?

Dan: Yes they did Dave. But this is simply not the case. If they had done a full power frequency response they would have found that this wasn't true. They could have also done a slew rate measurement with an oscilloscope and found that this was not the case. They based their decision on the THD + N measurement. The Audio Precision One is an incredible test measurement system. If people would only take the time to really learn how to use it, they wouldn't make incorrect assumptions, and mislead people, including themselves.

Dave: If you have high harmonic distortion doesn't that also indicate that your intermodulation distortion is high too?

Dan: In most cases yes. But here again The LNPA 150 doesn't follow the norm. The CCIF I.M. distortion reaches to about 0.002% near clipping. This is not only very low but it's insignificant when compared to a loudspeaker. I have this dream that one of these days someone will be kind enough to measure a loudspeaker the way most amplifiers are measured and be kind enough to publish it.

Dave: If I read you right Dan, then your telling me that the THD + N measurement is near useless?

Dan: Not entirely; it's a good start, but it really needs to be expanded. For example: If you take a THD + N measurement in a power amplifier it really needs to be done over the entire frequency range and at different power levels. If the unit is really linear the THD + N measurements should remain the same, and the measurements should overlap each other. The LNPA 150 does exactly that.

I brought one of the LNPA 150's in for measurement to a well known and respected audio firm. The engineer who did this test said he had never seen an audio power amplifier as uniform as the LNPA 150. He kept bringing in other engineers and and pointing to the measurements taken and exclaiming that this is what well designed amplifiers should measure. He also said that he had tested a lot of very expensive, and well known power amplifiers that were no where near the uniformity of the LNPA 150. Note the remarks from Dave Moulton in his review. That uniformity is audible and preferred by intelligent listeners.

Dave: What's all this stuff I hear about high current? I get plenty of power from the LNPA 150's and the heat sinks don't even get warm after I've had the volume cranked for over an hour.

Dan: I'm glad you asked that because this is one of the greatest myths presently perpetrated by poorly informed and under-educated people. I am going to back in audio history a bit to explain how this started.

Back in the earlier days of audio, speaker designers were often not very careful with the crossover design and introduced some very low impedances at certain points in the loudspeaker. This gave birth to high current design of power amplifiers to fill that need.

Today, and for at least the last 10 years, this is more a rarity than the norm. The great majority of loudspeakers today are in the 4 ohm to 8 ohm range. There are a few exceptions. Some of the Martin Logan Electrostatic Loudspeakers impedance dips to one ohm at 20 Khz. Will this require a "high current amplifier" to run this loudspeaker? The answer is no because only the harmonics of music are there, not the main signal. The power needed to to produce harmonic information at that frequency is pretty low. The great bulk of music falls in the range of the piano, which is from 27 hz to 4.8 Khz. If I remember correctly a pipe organ can go up to 8.2 Khz. According to the literature provided by Martin Logan the impedance in the primary musical range is a nominal 4 ohms.

Just to give you a little anecdotal evidence, I have a customer who has a pair Martin Logan CLS IIZ's. He was attempting to "break in" the LNPA 150's and found that after playing them at loud volumes for hours he could not get the heat sinks hot. Nor could he get the LNPA 150's to fail. There are other loudspeakers that go down to the 2 ohm range but the LNPA 150's will deliver at least 220 Watts rms into 2 ohms.

Dave: Does that mean the LNPA 150's will power any loudspeaker?

Dan: No, The LNPA 150's are not designed for very inefficient loudspeakers such as Ohm Walsh 5's or the big Apogee ribbons. For speakers such as this my recommendation is a power amp that will deliver 300 watts plus into 8 ohms and 500 to 600 watts into 4 ohms. For more information on the myth of high current there is an article written by E. Brad Meyer in the Stuart Robinson Home Theater web site.

Dave: What speakers in your opinion make a perfect match with R.E. Designs equipment? Do you have a favorite?

Dan: I do have a favorite speaker. I personally prefer full range speakers, and the best I have ever heard are Fried Loudspeakers. I have a set of rebuilt Fried G3's here and they make far less mistakes than any speaker I have heard to date. This loudspeaker was far ahead of it's time, even though it was designed almost 15 years ago.

Dave: One of the things I notice about your amp is that it doesn't have the "overblown" bass of most solid state amps. If it isn't high current, then what is it?

Dan: This one of the things that I designed out of the LNPA 150. I set a pretty uniform output impedance in the primary music range to get rid of this effect. The result is a more uniform and natural bass that is in good relationship to the rest of the music. In all of my days as a musician that kind of bass is only found in the sound reinforcement equipment one hears at concerts. This does not happen with non-amplified musical instruments.

Dave: I'm confused here Dan, are you on the objectivist side or the subjectivist side?

Dan: I'm a registered independent and proud of it. I've talked about some of the deficiencies in objective reviews. Now I'm going to talk a little about the some of the deficiencies in subjective reviews.

I have noticed a few things that seem to predominate in subjective reviews that I am convinced are questionable. I have also had number of conversations with some of these reviewers that have left me incredulous. One of the most questionable things that some subjectivist reviewers do, is to use what ever loudspeaker they have in house as their "reference". This is all well and good but you have to be very aware of the deficiencies of the loudspeaker you are using. Most subjectivist critics are sadly unaware of this. The problems of loudspeakers in general are well known and well documented. I'll give you a few examples Dave.

One reviewer claimed that I had a "phase" problem in the lower mid range of the LNPA 150. This is not only false but physically impossible in any well designed audio amplifier. What the reviewer is hearing is the crossover changing phase when transitioning from the woofer to the midrange of the loudspeaker. An Impedance vs. Phase plot was probably available from the speaker manufacturer but the reviewer chose not to consult it. The thought occurs to me that maybe he wouldn't have understood it. The same gentleman said that the vocals were too sibilant and again the amplifier was to blame. Well this is getting interesting. Dave I would like you to say the letter "S "outloud.

Dave: "ess"

Dan: Did your hear the sibilance when you did that?

Dave: Yes I did.

Dan: That's from your tongue hitting the roof of your mouth and forming the sibilance.

Now in all fairness some microphones and loudspeakers can exaggerate this effect. Some recording studios use a "de-esser" to decrease this effect and some don't. Amplifiers don't do this. Some will mask this effect with noise or distortion or both. Here again the reviewer was totally unaware of what really causes this problem.

The other thing that seems to predominate in subjective reviews is the continual discussion of subjects such as imaging, and totally ignoring tonality and accuracy. This is music we are talking about and the "cues" in music are auditory not visual. I was talking about this very same subject to a customer of mine. I asked that when he went to hear the local symphony did he concern himself with imaging. He replied "no". I remarked that his eyes were on the orchestra and that provided the visual image he required. Many people appear to require a "visual" image to help them "hear" the music. Most of the serious listeners that I know will close their eyes when listening seriously to limit any visual distraction. So much for the visual effects of stereo. This attempt at this "visual" effect has given birth to equipment that will sacrifice the basics of musical reproduction, such as frequency response, noise and distortion. This is the wrong way to go. What's really needed here is for loudspeakers with better dispersion, characteristics, not overly focused and inherently failed attempts at an unreal "image".

Sausilito Audio Works Loudspeakers have made a tremendous contribution in this area. For those of us who have had the experience of listening to live unamplified music know that it is very diffuse and really has no viable visual image. Remember, music is an auditory event, unless you prefer MTV. For once I would like to hear from subjective reviewers about the tonality and accuracy instead of room placement. When I listen to Itzhak Pearlman I want to hear the beautiful tones that he gets from his violin. I am far less concerned about where I imagine his violin is in my listening area. This is music and the "cues" are auditory.

The other complaint I hear constantly is how the sound of the equipment changes, particularly at night when supposedly the AC electrical lines are "quieter". Well that may be the case but one of things I enjoy about listening to music late at night is that the surrounding ambient noise is far lower than in the daytime. No constant background of cars, trucks, and people. Some reviewers go farther than that to proclaim greater changes over time. I would like to suggest that maybe the mood swings of the reviewer are more a factor here. It's really hard to believe I am reading a supposedly educated adult in some of these reviews. When I am in a foul mood it sure does affect how I hear things, how about you Dave?

Dave: You got that right Dan. When I want the sound of my system to change I just put in a different recording than what I was just listening to. That's a big enough change for me. Let me ask you another question. Do you think that these reviewers who claim they reference live music to what they listen to are sincere?

Dan: Yes and no. I'm convinced that the live music they reference to is live amplified music. I don't get much sense at all that they have experienced enough live unamplified acoustic music.

The other thing that most of these reviewers seem to ignore is what happens in the recording studio. Microphone placement, processing, and the subjective judgment of the recording, mix down, and mastering engineers are rarely discussed. It's almost that they seem to not exist. To paraphrase someone I know, "I used to be an audiophile until I found out what they were doing in the recording studio." The near total lack of education here is a great disservice to the music loving public.

Dave: I've noticed two things about your set up Dan. I see acoustic foam all across the wall behind your speakers and I don't see any of those designer cables. What gives here, Dan?

Dan: I'll explain the acoustic foam first. What you see here Dave is called a "live-end", "dead end" set up. By covering the wall behind the speakers with acoustic damping material, I have created the "dead end" behind the speakers. This drastically reduces back wall reflections from the loudspeakers to give a much more coherent sound. The wall opposite of that is untreated and "live". This technique is used by a great number of studios. Trust me when I tell you what a difference it makes. When I first moved my listening area in here, I could barely stand to listen to it. With the back wall "dead ended" it's created a very pleasurable space.

As far as the cables are concerned I have not heard to date any of these so called designer cables improve much of anything. In fact I generally hear the opposite. Everytime someone gives me a demonstration of the so-called latest and greatest cable versus the Belden cable that I use, I hear anything from diminished dynamics to gross distortion. I remember being at someone's place and getting a demonstration of what different power cords would do to his power amp. The good old Belden won out readily. All the others degraded the dynamics and clarity. I have come to the following conclusion about these so called designer cables. They are really an attempt to reduce the dynamics of the equipment so the system "sounds better" in an acoustically untreated or poorly treated room.

Let's face it; Acoustic damping material is cheaper than the designer cables, and can be cosmetically enhanced for the Wife Acceptance Factor. The reproduction of music is all about preserving the dynamic range of a recording not limiting it. Music without this dynamic range is just a shallow imitation of the real thing.

Dave: I notice that you sell audio interconnect cables, isn't that a little hyporcritical?

Dan: The cable I sell is Belden #8422 microphone cable and I don't disguise it with any shrink tubing or any other covering. This is an excellent shielded cable with low capacitance to boot. By the way; I sent two pair of these cables out to an audiophile critic for a year. I called him and asked him how they were doing. His reply was that they worked fine with just about everything. He has also, to date, refused to review them. I suppose that $50.00 a pair is too low in his market, considering the megabuck cable he has already recommended. I think the shoe is on the other foot.

The R.E. Designs SCPA 1 six-channel Preamp with the matching SB 1 Switch Box is a formidable match for any Preamp on the market regardless of price.

Dave: Touché Dan. One very obvious quality I notice about your electronics is that it's very quiet. Is that an important part of your design philosophy?

Dan: Definitely, and you have touched on one of my favorite subjects. One of the great things given to us from digital audio is far better signal to noise ratio, lower distortion, and greater dynamic range than was possible from tape or vinyl. Reducing the noise in playback equipment yields more information to be heard out of the loudspeakers. This is not immediately obvious to many listeners initially.

With lower noise, in time, one finds that decay is better presented, musical information that was buried comes out more prominently, and harmonics of the musical instruments involved are clearer, and the overall dynamic range is improved. Most of us listen to music in small rooms, typically 15 ft. by 20 ft. sometimes a little smaller and sometimes a little larger. Our average listening level is only 80db spl at the listening position. Typical average amplifier power to the loudspeaker is in the 1 to 2 watt range. These type of numbers mean that if you want greater dynamic range, you must lower the noise floor. Increasing amplifier power levels not only aggravates your neighbors, but it overloads the listening room and, as is the case with most loudspeakers, the distortion rises dramatically.

Noise generally comes from three sources; whatever RFI and EMI is in the air; whatever is conducted through the AC line; and whatever the electronic equipment itself generates. I use an all metal chassis that is earth grounded at the AC line. By earth grounding the chassis, I have "wrapped" a shield around the internal circuitry to protect it from stray external RFI and EMI.

Reducing AC line noise is done in a more "layered" fashion. At the AC input I use a standard common mode line filter that does a great job of attenuating high frequencies that are conducted along with the 60 Hz line frequency. That leaves lower frequencies and stabilization of the supply for a wide range of AC line voltage. Well designed linear power supplies will do an excellent job of rejecting low frequencies below 1Khz, but not the high frequencies. Therefore the "layered" approach is called for. The AC line filter attenuates the high frequencies and the power supply attenuates the lower frequencies. I have had great success in the field with this approach.

I have customers in the New York City metropolitan area and in Taipei Taiwan. Guess what! I'm not getting any complaints, and I'm getting feedback that all those fancy line filters out there don't help, and that the units work just fine on their own. I have not included surge suppression in my equipment but an ordinary surge suppressor outlet strip from your local office supply store will do just fine.

This reminds me of a story of a customer of mine out in the mid-west. When I recommended the use of a surge suppressor. He said that he had heard from other people that these units made things sound worse. I then asked him the following question. What is the sound of a voltage spike tearing apart your power supplies and the sound of your wallet opening to pay for repair bills? Considering the ferocity of lightning storms in the mid-west I thought it was a good question. About a year later we talked again and I asked him if the use of a surge suppressor affected the sound of his equipment. He replied that he had tried it both ways and found that the surge suppressor had no audible effect on his equipment.

Electronic noise that the equipment itself makes is the toughest to explain so I need you to bear with me. Noise of this type can come from three sources: grounding, lack of shielded inputs, and thermal noise. I will start with grounding first. You have probably heard of a star ground, but you don't really know what that means. Right?

Dan: A star ground is configuring the grounds to meet in one central place so in effect the "star" is ground central. This is almost always done at the power supply. Many people claim they do this but the chassis is usually the same ground as the audio signal ground.

Note that the chassis is earth ground for R.E. Designs. Also notice how the grounding is done in the SCPA 1 for example. Each individual channel has it's own ground but the grounds do not meet until they reach the power supply. Also notice that the ground plane is on the top side of the board. This helps to "shield" the components on the board from stray noise also.

The general idea of the "star" ground is to direct all ground currents to one place and avoid "ground loops", or to rephrase that, ground currents going in other directions than back to the power supply. The sum total effect is that it lowers noise and it also helps when other equipment is connected to it by keeping those "ground loops" to a minimum.

Dave: I see a lot of amplifier signal to noise specifications that are better than yours Dan; but they sure don't sound as quiet.

Dan: That's because they rate their signal to noise ratio at full power... instead of at 1 watt where they are supposed to. If you take their signal to noise ratio and crunch the numbers you get signal to noise ratios at or below 90db at one watt. If you inflate my signal to noise ratio to full power you will get close to 120db. Most consumers don't know that.

Dave: This sounds like a manipulation of the numbers to make it look better than it really is.

Dan: You got that one right... and because most of our listening levels is done between 1 and 2 watts on average, the one watt signal to noise ratio is a more accurate and useable measurement.

Dave: Your equipment is so quiet Dan. I'm sure you would always hear the difference in a head to head test. Have you ever done a double-blind test with it?

Dan: I have a great story about that. One Saturday morning I went to this person's studio, who happened to be a very well-known audiophile in the Boston area. I was there to do a field test with a prototype pre-amp and D/A Converter that I had designed.

First, we played some music and listened to his system. You know... the usual. Then I hooked up my two units in his system. Wow! The noise floor fell so low that both of our jaws dropped. It was that blatantly obvious to the both of us. You could hear so much more of the music. Now mind you, this guy was a die-hard double-blind ABX adherent who kept saying that he heard no differences between records and CD's, and he was out to prove it. He invited me to bring back my D/A Converter for the ABX test but not the pre-amp. I'm sure the reason is because if we used my pre-amp, you would have clearly heard the differences between records and CD's. He also made sure to tell me as I was leaving, that I was not to tell anyone that his system was so noisy! Can you imagine what his pre-amp sounded like?

If I have learned anything over the years since I have been in the audio industry, it's that a great majority of business is usually based upon a personal or political agenda which, as far as I can tell, has nothing to do with proper engineering or the accurate reproduction of music. I really detest getting into the politics that surround the audio industry. As far as I am concerned, it has no place in audio engineering.