There isn't one "best", but there are definitely "better" -- just my not so humble opinion!
Need An Amplifier That Can Make Any Speaker It's Bitch?
- Thread starter Andre Marc
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There isn't one "best", but there are definitely "better" -- just my not so humble opinion!
Reliability is a key factor in selecting components. There are few things worse than needing two strong people to pack an amplifier in its crate, cart it off to a shipper, wait for it to be fixed and finally having to find that strong guy again (who didn't realize when he accepted the first request for help that it would be such a difficult job) to help you unpack and re-install it in your system. Audiophile amplifiers today are NOT 20 pounds like the Dynaco Stereo 120 was in 1972.
Years ago, I needed service on one of my IRS-V woofer amplifiers. It was a THREE man job to un-install it and pack it up and re-install it. I hope I don't have to do that again. Shipping and insurance is very expensive because of the weight and insured value, and having two service technicians come out to the house to do it (outgoing and incoming) isn't cheap either.
Steve,
Internal built quality and reliability are very different thinks and both too important to be debated lightly as opinions.
The criticism that was made in the thread was not founded in the real operation of the device and IMHO could be misinterpreted by anyone who does not have a solid technological background. I hope that that this forum has more ambitious technological aims than starting a random photographic analysis of equipment internals.
However if people however insist on it I can recommend this site http://www.hifishock.org/electronics/ - it even has an option of showing 100 random photos!
Thank you Andre for reaching out to him. He scores a big point with me for caring to write a response. Kudos to manufacturers who take the time to do that.
Alas, you asked him the wrong question. Everything he is mentioning is on record here and not the issue at hand. This is the issue as posted in the first reply:
As I noted and others agreed, the amp does have oversized heatsinks so we are not concerned about the transistors dying. But rather the elevated temps shortening the life of electrolytic caps. Here is a sample graph showing the lifetime versus temperature:
As you see, there is an exponential drop in lifetime of such capacitors based on temp. It should make intuitive sense as what causes them to go bad is the electrolytic drying out and any liquid evaporates more and more as you increase temps.
Anyway, I am still wondering if the amp lived up to the tag line you gave it for the thread title. You said in your original post that you will be testing it with maggies. Last time I did an amp shoot out with them (going back to 1980s) my friend had a Bryston amp with similar power to this unit. I brought over my Carver receiver with 200 watts and Class H and it substantially increased the dynamic range and bass out of his maggies. So I am curious how with less than half as much power you managed to get them to perform to their potential.
What amp did you compare them to? Have you tested them against much cheaper mass market amps? Any class D amps in its price range or even lower? I don't know what to do with your one and only statement that they were "amazing."
Amir, I will ask this but one time. I don't want you or anybody else to post internal pictures, with annotations, or to post hypothetical design flaws, theories about reliability, or other objective comments pertaining to performance UNLESS you decide to either borrow or purchase that product and conduct all the tests you wish and post all the graphs you want. If you have NO intention of having the product in your own home, and will never listen to it or use, do not do this again. If it is done again, i will see it as a slap on the face, and an immense show of disrespect. Is that clear? And nice move getting your attack dogs to join in. Some very curious posters joined the thread.
To answer your fair question;
I compared the amp to the identically priced Onkyo M5000R ($2500), and to the Simaudio 760A ($8000) on both Maggie MMGs and Maggie .7s.
The Redgum amp was very close to the Onkyo, as a matter of fact, differences may be chalked up to the preamp ahead of the Onkyo. Soundstage depth was
hard to pick between them, midrange was just as transparent. The Onkyo had a bit more ease to the top end. However bass articulation and precision was superior
with the Redgum.
The Simaudio is more refined in the mids and highs than the Redgum, but same as above, the bass was a bit tighter and more articulate with the Redgum.
It drove the .7s to the most satisfying levels of all the amps, and def. got it to open up. The others two were a bit on the mellow side with the Maggies.
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Steve, what do you think of a poster with who has no interest in a $2500 amp saying it is the WORST looking product he has seen in THIRTY years. THIRTY years!!!!!
What purpose does that serve.
Of course there has been little interest..the thread was poisoned from the beginning. I think it is presumptuous to say there is no interest and to talk about reliability. I posted that I have a friend with TWO redgum amps he has been running for ten years straight with zero issues. This fear mongering based on theory and hypotheticals needs to stop.
You can ask anything you want Andre. It doesn't mean we will have an engineering book burning session outside the library to warm your cockles. You bring what you know of a product and the rest of us bring what we know. We are not about censorship of membership under any excuse or reasoning you want to make up.
My fair question remains unanswered. Let me remind you what the title of your thread is: "Need An Amplifier That Can Make Any Speaker It's Bitch?"
In what manner did this amplifier accomplish that objective and how did it relative to the other amps? Or is this a line you are repeating but don't know what it means?
So I ask again who you are addressing if by your own admission no one is interested and you only want to write for the interested.
Theory? There is no theory here. These are practical aspects of engineering that only the people who have lived through it know. I can show you a thousand references on the problems we are talking about. Fact that you don't understand them doesn't make them theory. We know what is good design and what is not. Instead of being emotional and wasting forum bandwidth on rants, how about spending a few minutes to learn what makes these products tick? You know, to be able to open the hood and know where the dipstick is.
Since this product is Australian, how about learning about capacitors from the top engineering webcaster and respected Australian engineer, Dave Jones:
Did you hear it? "Heat can kill them?"
You are reviewing technology products for goodness sake. Don't advocate ignorance of it as if that is the way the world should be. Good grief....
Sorry, Amir your answer is bull ****.
It is the response of an unreasonable person. When I have a product in house that I can interface with, listen to, and evaluate at my finger tips, I KNOW what I am talking about.
You post theories and innuendo about a product you know NOTHING about. Finding pictures and creating graphs is not knowing the product, it is being provocative and forcing YOUR agenda on every one else.
So let's end the lie that you "know" what you are talking about without first hand experience with a product.
My answer to you is the amplifier drove difficult loads with ease, running cool, with tremendous dynamics.
Your condescending, deflective garbage is not worthy of a reply. 21 straight years of continuous production, with continued refinements to the product line, and absolutely no burned out amplifiers the designer is aware of.
But why let the facts get in the way of your argumentative, objective nonsense.
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And maybe you need to open the box and learn what is in it. This person did: http://liquidaudio.com.au/redgum-australian-quality-you-decide/
"The manufacturer even responded, stating that using better parts would not make any difference, an extraordinary claim and one which is factually and technically incorrect. Redgum stated that they used the lowest quality of parts they needed to, to build the amplifier, which is not a great endorsement of the thinking behind production. "
[...]
"I had heard rumours, from people in the know and who I trust, that Redgum gear was overpriced and that the parts used were not the best. I was recently able to fin out for myself, when a customer brought in a Redgum RGi120 amplifier for service.
One of the twin volume controls (more on that later) had come loose and the speaker connectors were also loose. Popping the lid, I was surprised by what I saw…"
[..]
"The Redgum also contained a modest input switching board with selector and volume pots mounted directly to it. This is good, the pots and switches chosen were however very basic. Anyway, it was the other parts inside that had me scratching my head. We are talking about cheap Chinese parts here, the same parts that are sold by Jaycar and Altronics."
[...]
"The capacitors in this Redgum RGi120 were low-spec, 85 degree rated Leylon/Samwa/Suntan/HungLong brand. These are not the sort of capacitors one would expect to find in amplifier that costs over $2,500. The resistors were also Altronics/Jaycar metal film types, with poor temperature coefficient, poor noise specs (guessing here based on similar priced Chinese parts because I could find no specs, not a great sign) and worth cents each.
The main filter caps which are so important were Leylon brand and similar quality to the other small caps. I hate Leylon caps and others like them. In my opinion they do not belong in an amplifier like this, and yes they really DO make a sonic difference, and a difference in terms of reliability. There are lots of greencaps, which are a cheap type of metalised polyester capacitor and MKT types by ERO/Wima/Siemens have better characteristics, but of course cost more too.
The transformer was again an Altronics/Jaycar Chinese toroid. It looked to be around 300VA rated, which would be marginal for the power spec of the amp. Perhaps it was 500VA item, I don’t know for sure. The output transistors were just cheap Exicon types. Exicon is a Chinese brand known to be previously associated with fakes of other higher spec transistors in the past – you can read about this here. They are not what you would hope to find in an amp like this."
[...]
"Everything is quite nicely laid out on the boards, the boards are of reasonable commercial quality at this price, there is some glue used to hold parts to one another and this is good practice in places. Trimpots are locked with sealant to prevent movement, but the mechanical construction of the chassis and the wiring is agricultural."
[..]
"Yes, this amp is made in Australia, which is a great thing. My concern is that with just a small increase in the bill-of-materials cost, this amp could be made from some higher reliability, higher quality parts. Everything about this amp would be better with better parts, especially some low ESR, high ripple current, high temperature Panasonic/Elna/Nichicon/Rubycon caps throughout."
[...]
"Trying to maintain channel balance is hard (almost impossible, not impossible like time-travel, but really hard!) when you have to adjust two volume controls independently. Seriously – who thought that two separate volume controls was a good idea? I have seen rubber bands placed around these dual volume controls in an vain attempt to get them to move in synch with one another! In my very humble opinion this is a really bad design choice, guaranteed to create near-constant channel imbalance and it is not surprising that almost all other manufacturers use one volume control, and a balance control that can be used to correct channel imbalance when needed. As for the amp having a ‘key’ to turn it on – let’s just leave that there…
I’ve seen time and again how premium parts can make a real difference to reliability and performance. Capacitors and semiconductors in particular vary enormously between nominally similar parts based on one spec. Spending a few cents more per part, on better parts, will potentially decrease a manufacturer’s margin, but will usually add increased service life and improved technical performance to a product. This will then add value, long-term. I believe it is false economy to use the cheapest parts you can get away with in a product."
[...]
"As for the loose volume knob I spoke about earlier, these volume shafts with knobs attached are held to the potentiometer shaft by a small piece of cooling hose, the same cooling hose you might find in a car’s cooling system. These have been hand-cut to length and then push-fitted and glued on to the potentiometer shafts. I was surprised, lets just say that. Sure, it works and I am a fan of simple solutions, but there are more elegant and robust solutions to this problem. The volume knob had just been pulled out of the rubber hose because the glue had failed. The shafts didn’t even line up with the potentiometer mountings – perhaps that explains the cooling hose and the flexible attachment it allowed. Because of the slope of the shafts, the knobs are also not parallel to the front panel."
The above was the first link that showed up when I searched for reliability of the brand. As you see it is highly consistent with the view we have presented here. As I said, as engineers we can quickly spot issues from our experience.
You have far, far to much time on your hands. If you have no intention of listening to this product, and are not shopping in this category, i have no,interest in your responses.. See ya.
Yes they are much cheaper. But you need to realize that the NC500 is just the output stage, you also need an input stage to make a complete amp. The Acoustic imagery amp (although probably the best deal in audio for amps) uses a basic IC opamp based input stage.
I think that we may be seeing some confusion as to the beliefs and understandings of some of the posters on this thread. I'm sure that Andre would not be advocating for a badly designed and poorly constructed product if he believed that said product would likely have a high failure probability, and/ or be some kind of sham product. I also believe that Ack and Amir would probably be willing to pull back on their criticism of the inner workings of said product, if they knew that a) the value was more than acceptable and b) the sound was at least as good or better than any competing product for the same price.
As a consumer, and not a professional attached to the hobby, the sound is paramount to me...BUT with the understanding that a product I am acquiring is going to have a) decent enough build quality to allow me to expect and enjoy a long enough reliability factor, to at least not have to concern myself with this issue very often. Obviously, the life of any product varies, but again, as a consumer, I would expect several years of trouble free service. ( Or, at the very least a manufacturer who will stand behind his product now and into the future).
This as a consumer.
IF, as the more technically inclined members here are postulating, that said product's build quality is sub-standard...and therefore likely to lead me to ongoing quality and reliability problems, then I absolutely DO want to know about that. However, I also think that a certain disclaimer by said members needs to be added, that says something like: "We have no real experience with this exact piece and manufacturer and that we have NOT heard said piece. Also, we have no information as to the expected reliability of said piece, but given it's overall build quality, buyers beware."
Simply by looking at the innards of the piece would not preclude me from buying the piece in question, even IF i knew it was built to a sub-standard quality, but it would alert me to the fact that the designer has a certain method of construction. If said piece was superb sounding and I knew the manufacturer/dealer was willing to stand behind the piece, I would certainly still consider it as a possible purchase. As they say, all knowledge is good.
Would any of you gents disagree...???
As a consumer, and not a professional attached to the hobby, the sound is paramount to me...BUT with the understanding that a product I am acquiring is going to have a) decent enough build quality to allow me to expect and enjoy a long enough reliability factor, to at least not have to concern myself with this issue very often. Obviously, the life of any product varies, but again, as a consumer, I would expect several years of trouble free service. ( Or, at the very least a manufacturer who will stand behind his product now and into the future).
This as a consumer.
IF, as the more technically inclined members here are postulating, that said product's build quality is sub-standard...and therefore likely to lead me to ongoing quality and reliability problems, then I absolutely DO want to know about that. However, I also think that a certain disclaimer by said members needs to be added, that says something like: "We have no real experience with this exact piece and manufacturer and that we have NOT heard said piece. Also, we have no information as to the expected reliability of said piece, but given it's overall build quality, buyers beware."
Simply by looking at the innards of the piece would not preclude me from buying the piece in question, even IF i knew it was built to a sub-standard quality, but it would alert me to the fact that the designer has a certain method of construction. If said piece was superb sounding and I knew the manufacturer/dealer was willing to stand behind the piece, I would certainly still consider it as a possible purchase. As they say, all knowledge is good.
Would any of you gents disagree...???
Im just on a mission of gathering and sharing information at the moment. You can either, listen to what I have to say, or blow it off as nonsense. Your choice and everyone's choose. This is what forums are for.
And if you believe that twaddle, I have a very nice opera house for you to buy.
Points:
65 Watts @ 8 Ohms corresponds to an output of close to 23 Volts RMS.
23 Volts RMS across a 0.5 Ohm load = 1,058 Watts.
Trouble is, it can't be done. Such a claim ignores the fact that real output devices suffer losses. Although those losses can be kept small, they are not non-existent.
The other issue is your claim that they employ no negative feedback. Not possible. ALL amplifiers employ NFB to linearise operation. EVERY single one. Even those so-called no feedback SET amps. A triode uses an internal feedback system.
I think that we may be seeing some confusion as to the beliefs and understandings of some of the posters on this thread. I'm sure that Andre would not be advocating for a badly designed and poorly constructed product if he believed that said product would likely have a high failure probability, and/ or be some kind of sham product. I also believe that Ack and Amir would probably be willing to pull back on their criticism of the inner workings of said product, if they knew that a) the value was more than acceptable and b) the sound was at least as good or better than any competing product for the same price.
As a consumer, and not a professional attached to the hobby, the sound is paramount to me...BUT with the understanding that a product I am acquiring is going to have a) decent enough build quality to allow me to expect and enjoy a long enough reliability factor, to at least not have to concern myself with this issue very often. Obviously, the life of any product varies, but again, as a consumer, I would expect several years of trouble free service. ( Or, at the very least a manufacturer who will stand behind his product now and into the future).
This as a consumer.
IF, as the more technically inclined members here are postulating, that said product's build quality is sub-standard...and therefore likely to lead me to ongoing quality and reliability problems, then I absolutely DO want to know about that. However, I also think that a certain disclaimer by said members needs to be added, that says something like: "We have no real experience with this exact piece and manufacturer and that we have NOT heard said piece. Also, we have no information as to the expected reliability of said piece, but given it's overall build quality, buyers beware."
Simply by looking at the innards of the piece would not preclude me from buying the piece in question, even IF i knew it was built to a sub-standard quality, but it would alert me to the fact that the designer has a certain method of construction. If said piece was superb sounding and I knew the manufacturer/dealer was willing to stand behind the piece, I would certainly still consider it as a possible purchase. As they say, all knowledge is good.
Would any of you gents disagree...???
I agree with you Davey
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