Introducing the New HiFi Miser Forum-As discussed by Andre Marc

[amirm]

The objectivists often attempt to prove that the subjectivists are wrong, or they ask, sometmes demand, evidence, proof or verification of the other's observations. Or in the case of that amplifier with the heatsinks on the bottom, they point out that the design is flawed without solicitation for comment. That leads to acrimony and a hostile environment for discussion. The subjectivists often just want to be left alone to enjoy their music or they want to share their experiences on friendly forums without having to prove their opinions. Many have left this forum for friendlier places.

The issues of equipment reliability runs across both camps. In my article on Onkyo AVR, I criticized similar issues to the amp in question here:

Unfortunately we see a recipe for a accelerated failure of a capacitor in this unit. As you see in Figure 4, the rectifier, the large flat device, is touching the capacitor. The large size of the rectifier indicates that it is designed to dissipate fair amount of heat. Due to direct contact, the heat directly couples to the capacitor causing its operating temperature to be much elevated had there been an air space between the two components. While there was an easy fix of simply bending the rectifier away from the capacitor, this is the kind of flaw that should have been caught during assembly or better yet, more distance designed into the PC board that holds the components between capacitors and heat generating sources.

More disappointing though sadly very common is the temperature rating of the capacitor. As I have marked, the capacitor is the common 85 degree C rated type. While this is plenty high for most electronic circuits, it is not in the vicinity of high power devices and inside of a cramped AVR with so many channels of amplification all generating heat. I would like to see capacitors rated at 105 degree C in such scenarios. To wit, next time you are shopping for PC desktop power supply, you may want to peer into its venting slots and see if you can read the temperature ratings of the caps. If they are 85 degrees and not 105, I would walk away from it. High quality ones will always have 105 degree C capacitors given the very close proximity of them to the high power components.

Figure 4: Power supply rectifier and filter capacitor touching, leading to shorter life.


[...]
The biggest disappointment is not the capacitors but the two fans. They are buried under the two metal square boxes one each side of the power supply. They are slanted 45 degrees, blowing sideways onto the heat sink. You don’t need a degree in physics to realize that air blown across the heat sinks is not going to uniformly cool them. The fins closest to the fan will get the bulk of the air movement, and the rest get substantially less. And the air that does get through is turbulent due to obstruction of the fins.

Proper cooling would call for smooth air movement between the fins which would call for the fans to be above or below the heatsink. That would make the unit much taller which was likely the reason it was not used. This compromise means some of the amplifier channels will run hotter than others, and in theory, have shorter life.

To add insult to injury, the fans kick on based on specific volume level rather than heat generated. Better design calls for a temperature sensor to keep the fans off as much as possible if the unit has ample circulation. But no, as soon as you turn up the unit, the fans click on saving a few cents in component pricing, but bringing with it the higher noise of the component, and shorter fan life.

Actually the right design would have called for a much larger heatsink so that no fan would have been necessary. That of course costs more money as heatsinks are expensive as is space to house them and shipping cost to get us the unit from far away manufacturer. So compromises were made, hoping one wouldn’t notice. And probably no one does.

I am being harsh here since there is an unwritten rule that in the home consumer market that amplifiers are fanless and silent. Professional units use fans because they live in much harsher environments of cramped racks and outdoor applications (e.g. for live sound). But home units usually live in homes with less hostile temperature ranges that allow passive cooling if one does not aim to reduce cost. For the $1,000 that I paid for this AVR, it would have been a fair expectation to get an amplifier without fans.

Objectivists are the types that buy these AVRs instead of discrete amps high-end folks use. Yet, there was no protest. Instead, I was greeted by this first reply:

Nice teaching Amir.

So ask again, why do you seek protection for sharing of this technical information while the other camp does not? Why is it that they don't find it insulting but you do?

 

[Andre Marc]

First, this will be my first and last post about the previous Redgum thread.

Now, let us look at the actual facts.

I posted about the Redgum integrated amplifier because I thought others with hard to drive
speakers would appreciate having a look at a product specifically designed to drive hard loads.

-Contrary to what has been posted, I did not contact the either Redgum, or the importer, CCI, to review this amp.

I posted a thread on the Hoffman forum about Ron Brenay/New Record Day’s entertaining video review of the Magnepan
.7 speaker in which he declared that hat all the amplifiers he had in house were inadequately driving the .7, so he
had to resort to pulling out a vintage Carver amp rated at 400 wpc. I posted this video because I was in the process of purchasing a Maggie MMG,
and then was so impressed I arranged an extended in home audition of the .7 and wanted to get a balanced overview what amplifier would be required.

-Marc Phillips from CCI, a Hoffman forum member saw my post and contacted me asked if i wanted to try the Redgum RGi35ENR Black Series amplifier,
which was the first in line in the Black series, costing $2500 that was designed to drive speaker rated even at 2 Ohms. I said sure. This
unit was his personal unit he brought back from Australis to demo, and was impressed enough to want to bring in the line to the
US.

-I was also impressed enough that we discussed a review, but only after he signed a formal agreement to import the line. He did that.
I thought it would be nice post about the product here, as I was sure I was not the only one with a difficult to drive speaker.

-The first response was from anonymous poster from Australia who wrote the following:

"Heat sinks on the BOTTOM of the amplifier!!!???

"Insane. EVERYTHING inside the chassis will reach the same temperature as the output devices. Life-span of every electrolytic caps will be compromised. Bad idea.”

So his VERY first post is filled with phrases like “insane”, and “Bad idea”.

-I later determine that this poster, who claimed he had modded/serviced Redgum amps, said later in the thread they proved to be very reliable, and found the designer Ian Robinson to be
especially easy to work with. On top of that he admits he has not heard ANY Redgum amps designs since 2005.

-Amir, seeing the opportunity, takes it up on himself to join in, digging up internal photos of a similar, but not the same product, annotating it with all sorts of notes.
Then other posters show up, knocking the design. These posters clearly not only have to touched or heard this amp, but have no intention to, ever. Then a feeding frenzy
begins.

Then we get someone who claims it is the “WORST” product design they have seen in THIRTY YEARS.

We see posters speculating about the reliability of the amplifier, and one even having the audacity to discuss safety issues.
This is not only beyond the pale, it is obscene. Somehow, a false story line develops about the amp being prone to failure and
filled with the cheapest parts due the irresponsible and speculative posts. When they say "a little knowledge is a dangerous thing"
they ain't kidding.

In my world, when someone posts about a product, the correct, polite, and accepted way to express interest in the design is to make comments like:

“Interesting, I see the heat sinks are on the bottom, does the amp run hot?”. “Can you ask designer why he put the heatsinks on the bottom, it is possible
it may shorten lifespan of certain parts”.

-Despite the presumptuous attacks on the product, I emailed Ian Robinson, the designer, who by the way was on vacation, who took the time to provide
a detailed response to design concerns.

-Not ONE of the posters who attacked the product responded. Not one.

I realized then that all of the attacks were disingenuous, and the culture here is one that looks for a sacrificial lamb.

Amir, you have created a vibe here that has driven away droves of members. This is a fact. Jkenny, whose USB DAC i had in my system for months,
and really was a special product considering the price, and Tony Lauck, a very knowledgeable poster specifically cited you as reasons they bailed.

You are among the most smug, disingenuous, egotistical, and self righteous internet posters I have ever encountered. You need to look deep in the mirror.

Your MO is endless, circuitous arguments with no end game. When people start to get on to you, you smother them with long, long, multi paragraph posts
that are impossible to wade through. You bait and just chalk up the number of posts. Many posters have tired of the game

I understand you see your self as some self appointed “consumer advocate”. Audiophiles are big boys are not as easily duped as you think. Nobody asked for your help
and you are very presumptuous in your knowledge base.

Not only that, but it seems you pick and choose. What you did to Alex and John at UpTone audio was beyond the pale. Your “consumer advocate” crown leads to witch hunts.
I noticed you did not annotate poor Joshua’s $82,00 DAC, although posters felt free to insult and badger him with impunity.

I posted about the MicroZOTL 2.0 preamp/headphone amp, which actually comes with a clear acrylic cover so you can see all the internals. No notations there.

For the record I am right down the middle. I believe in science and art. When I hear unusual claims from a high end manufacturer, I want to to know more and
I want easy to understand explanations, but I also want to hear the product, if it interests me.

Now to debunk some of the things you have posted in the after math:

-I was NOT upset about being “shown up” by people with more engineering knowledge than myself. That would be just about everybody here.
I am not a technical person. I use my ears. However, I also would tolerate a piece of junk. And having been around hifi gear since I was a young
child, it would take me no more than a few minutes to know that something was junk.

No, I was upset about the lack of any common decency.

-I did not get “caught” hoping for anything. I knew very well there were many pics of the Redgum amps with out their covers on. I also know they
have been in business for 21 years. I know two local audiophiles who have been running their amps for 10 years day in day out.

Now to the amplifier: It has been on 24/7 for 5 straight weeks, driving 4 different speakers..Maggie MMG, Maggie .7s, Bryston Mini Ts, and Harbeth Compact
7ES3s. The first three are 4ohm nominal rated, and the Harbeth is 6 ohm. ALL have mid 80s db ratings. The amp is driving them all with more easy than any other amp I have in the house.
It is not only not warm, it is COOL to the touch.

BTW: I have no business, financial, or personal connection to either Redgum or CCI. In any shape or form.

An interesting note: John Atkinson of Stereophile just reviewed and measured the new Arcam A49 power amp, $5000. Not only does it have heat sinks at the bottom of the unit,
they are INSIDE the unit. There is a cooling vent along the front panel to assist in cooling. Unusual? Yes. Does it work? Yes.

So, the bottom line is, if you have questions or concerns about a product, regardless of the price, high or low, ask questions politely. Express interest or concerns
politely. It is really a very easy concept.

I post on the Steve Hoffman forum virtually about the same products I do here. I have never, ever had the kind of reaction I got here, or that UpTone got here, or that
Joshua from Believe got here. I have had people express polite skepticism, and even, very nicely, offer up alternative products that may be superior or as good for less
money.

Now two final issues:

The use of the term “bitch” in the title: Too bad. This is an adult hobby. I think anyone with a modicum of maturity knows this term was used tongue in cheek
and the fact one person made in issue means it is a non issue. People are under the delusion they have a right never to be offended. You don't. I and nobody else
here should have to walk on egg shells as not to offend ONE person. Sorry, the good of they many overide the needs of the one. If you don't ever want
to be offended, there are still hippie Utopian communes you can join.

Lastly, I DO apologize, sincerely, and completely, with out any hesitation, for the use of profanity. Anyone who was offended I whole-heartedly offer my
my regrets, and I will not repeat these actions.

 

[Andre Marc]

Reading this thread, I'm reminded of one of the rock anthems of my youth:

Battle lines being drawn
Nobody's right if everyone's wrong
People speaking their minds
Getting so much resistance from behind

Yeah, stop children, what's that sound
Everybody look what's going down

Andre, come back. I miss your music suggestions. Espers comes to mind. What a great band!

Ron, if you like Espers, check out Meg Baird solo albums. She is the female voice.

Also, i know you are heavy into progressive. I discovered The Silence, headed up by Masaki Batoh, of the Japanese prog band
Ghost. Their two albums, but especially the new one, Hark The Silence, is a mid blower. Recorded to analog, all live. Think
King Crimson, Soft Machine, Traffic, Caravan...just great stuff.

The Silence, and Meg Baird are all on Drag City..with vinyl, CD , and FLAC available.

 

[DaveyF]

First, this will be my first and last post about the previous Redgum thread.

Now, let us look at the actual facts.

I posted about the Redgum integrated amplifier because I thought others with hard to drive
speakers would appreciate having a look at a product specifically designed to drive hard loads.

-Contrary to what has been posted, I did not contact the either Redgum, or the importer, CCI, to review this amp.

I posted a thread on the Hoffman forum about Ron Brenay/New Record Day’s entertaining video review of the Magnepan
.7 speaker in which he declared that hat all the amplifiers he had in house were inadequately driving the .7, so he
had to resort to pulling out a vintage Carver amp rated at 400 wpc. I posted this video because I was in the process of purchasing a Maggie MMG,
and then was so impressed I arranged an extended in home audition of the .7 and wanted to get a balanced overview what amplifier would be required.

-Marc Phillips from CCI, a Hoffman forum member saw my post and contacted me asked if i wanted to try the Redgum RGi35ENR Black Series amplifier,
which was the first in line in the Black series, costing $2500 that was designed to drive speaker rated even at 2 Ohms. I said sure. This
unit was his personal unit he brought back from Australis to demo, and was impressed enough to want to bring in the line to the
US.

-I was also impressed enough that we discussed a review, but only after he signed a formal agreement to import the line. He did that.
I thought it would be nice post about the product here, as I was sure I was not the only one with a difficult to drive speaker.

-The first response was from anonymous poster from Australia who wrote the following:

"Heat sinks on the BOTTOM of the amplifier!!!???

"Insane. EVERYTHING inside the chassis will reach the same temperature as the output devices. Life-span of every electrolytic caps will be compromised. Bad idea.”

So his VERY first post is filled with phrases like “insane”, and “Bad idea”.

-I later determine that this poster, who claimed he had modded/serviced Redgum amps, said later in the thread they proved to be very reliable, and found the designer Ian Robinson to be
especially easy to work with. On top of that he admits he has not heard ANY Redgum amps designs since 2005.

-Amir, seeing the opportunity, takes it up on himself to join in, digging up internal photos of a similar, but not the same product, annotating it with all sorts of notes.
Then other posters show up, knocking the design. These posters clearly not only have to touched or heard this amp, but have no intention to, ever. The a feeding frenzy
begins.

Then we get someone who claims it is the “WORST” product design they have seen in THIRTY YEARS.

We see posters speculating about the reliability of the amplifier, and one even having the audacity to discuss safety issues.
This is not only beyond the pale, it is obscene. Somehow, a false story line develops about the amp being prone to failure and
filled with the cheapest parts due the irresponsible and speculative posts. When they say "a little knowledge is a dangerous thing"
they ain't kidding.

In my world, when someone posts about a product, the correct, polite, and accepted way to express interest in the design is to make comments like:

“Interesting, I see the heat sinks are on the bottom, does the amp run hot?”. “Can you ask designer why he put the heatsinks on the bottom, it is possible
it may shorten lifespan of certain parts”.

-Despite the presumptuous attacks on the product, I emailed Ian Robinson, the designer, who by the way was on vacation, who took the time to provide
a detailed response to design concerns.

-Not ONE of the posters who attached the product responded. Not one.

I realized then that all of the attacks were disingenuous, and the culture here is one that looks for a sacrificial lamb.

Amir, you have created a vibe here that has driven away droves of members. This is a fact. Jkenny, whose USB DAC i had in my system for months,
and really was a special product considering the price, and Tony Lauck, a very knowledgeable poster specifically cited you as reasons they bailed.

You are among the most smug, disingenuous, egotistical, and self righteous internet posters I have ever encountered. You need to look deep in the mirror.

Your MO is endless, circuitous arguments with no end game. When people start to get on to you, you smother them with long, long, multi paragraph posts
that are impossible to wade through. You bait and just chalk up the number of posts. Many posters have tired of the game

I understand you see your self as some self appointed “consumer advocate”. Audiophiles are big boys are not as easily duped as you think. Nobody asked for your help
and you are very presumptuous in your knowledge base.

Not only that, but it seems you pick and choose. What you did to Alex and John at UpTone audio was beyond the pale. Your “consumer advocate” crown leads to witch hunts.
I noticed you did not annotate poor Joshua’s $82,00 DAC, although posters felt free to insult and badger him with impunity.

I posted about the MicroZOTL 2.0 preamp/headphone amp, which actually comes with a clear acrylic cover so you can see all the internals. No notations there.

For the record I am right down the middle. I believe in science and art. When I hear unusual claims from a high end manufacturer, I want to to know more and
I want easy to understand explanations, but I also want to hear the product, if it interests me.

Now to debunk some of the things you have posted in the after math:

-I was NOT upset about being “shown up” by people with more engineering knowledge than myself. That would be just about everybody here.
I am not a technical person. I use my ears. However, I also would tolerate a piece of junk. And having been around hifi gear since I was a young
child, it would take me no more than a few minutes to know that something was junk.

No, I was upset about the lack of any common decency.

-I did not get “caught” hoping for anything. I knew very well there were many pics of the Redgum amps with out their covers on. I also know they
have been in business for 21 years. I know two local audiophiles who have been running their amps for 10 years day in day out.

Now to the amplifier: It has been on 24/7 for 5 straight weeks, driving 4 different speakers..Maggie MMG, Maggie .7s, Bryston Mini Ts, and Harbeth Compact
7ES3s. The first three are 4ohm nominal rated, and the Harbeth is 6 ohm. ALL have mid 80s db ratings. The amp is driving them all with more easy than any other amp I have in the house.
It is not only not warm, it is COOL to the touch.

BTW: I have no business, financial, or personal connection to either Redgum or CCI. In any shape or form.

An interesting note: John Atkinson of Stereophile just reviewed and measured the new Arcam A49 power amp, $5000. Not only does it have heat sinks at the bottom of the unit,
they are INSIDE the unit. There is a cooling vent along the front panel to assist in cooling. Unusual? Yes. Does it work? Yes.

So, the bottom line is, if you have questions or concerns about a product, regardless of the price, high or low, ask questions politely. Express interest or concerns
politely. It is really a very easy concept.

I post on the Steve Hoffman forum virtually about the same products I do here. I have never, ever had the kind of reaction I got here, or that UpTone got here, or that
Joshua from Believe got here. I have had people express polite skepticism, and even, very nicely, offer up alternative products that may be superior or as good for less
money.

Now two final issues:

The use of the term “bitch” in the title: Too bad. This is an adult hobby. I think anyone with a modicum of maturity knows this term was used tongue in cheek
and the fact one person made in issue means it is a non issue. People are under the delusion they have a right never to be offended. You don't. I and nobody else
here should have to walk on egg shells as not to offend ONE person. Sorry, the good of they many overide the needs of the one. If you don't ever want
to be offended, there are still hippie Utopian communes you can join.

Lastly, I DO apologize, sincerely, and completely, with out any hesitation, for the use of profanity. Anyone who was offended I whole-heartedly offer my
my regrets, and I will not repeat these actions.

Ok, so for me that's the end of it....
BIG KUDOS to Andre for his last highlighted point...BIG KUDOS.

 

[Rodney Gold]

The use of profanity is the red herring , the side sniping hyena attack of the product for no real reason is really what stinks of rotten fish.

 

[amirm]

I posted about the MicroZOTL 2.0 preamp/headphone amp, which actually comes with a clear acrylic cover so you can see all the internals. No notations there.

That's easy to remedy. Here is a quick annotation of that unit:

First observation would be the caps again. Notices as I am showing with arrows they are away from heat producing tubes. There is a black cap near the rear right that is close to what of the switching FETs. The FET (transistors) are not heatsinked and are acting as switches I think so I don't think they generate much heat. Either way, they are years ahead of the other amp that had the caps connected to the same heatsink as the power output mosfets.

Cooling is convection based with vents at the bottom front pulling air in and exhausting to the back center rear. Good part of that is the the path would be through the tube. The 90 degree turn though is inefficient.

Love the nice big annotations on the PCB. Single board for everything and not a bunch of boards thrown around.

There are two inputs on the back. The selector is a switch in the front. The connection to it is through loosely twisted wires traveling from the side of the chassis to the front. If your own interconnects look like those, then you can feel good about it . Mine are shielded coax and that is what I like to see. Likewise the output of the switch is a pair of unshielded wire going to the volume control. The output from that is also unshielded and untwisted. If there is some wisdom in using such wiring, it escapes me. It is a recipe for unneeded noise pick up.

The unit has outboard power. While I hate the bricks myself, from safety and regulatory point of view they are great because the units come pre-certified (assuming they are bought from reputable manufacturer).

This is all I can extract from the top view of the board. I went and looked but could not find a side-view so that I could read the markings on parts.

Overall there is nothing that jumps out here like an upside down heat sink or caps bolted to the same that the other amp had. It is a DIY budget design of course not at all the works of art we see in say, $20,000 amplifiers.

 

[amirm]

The use of profanity is the red herring , the side sniping hyena attack of the product for no real reason is really what stinks of rotten fish.

Some people like me and give me hugs from behind:

 

[kach22i]

I read this whole thread, and I'm bemused that the offenders love to play the role of the offended.

The tradition of professionals; scientists, doctors, lawyers, architects, musicians, engineers and so forth providing critical analysis and peer review of other's works is essential, and should not be censored by "walking on eggshells" as it was ironically stated.

So much drama, and to what point?

EDIT: The other thread is closed so I'll post this here.

http://www.digitalaudioreview.net/2014/07/redgum-black-series-rgi35enr-integrated-amplifier-review/

Far from just a cosmetic concern the heatsink lends this new RGi35ENR a presence that connotes serious business (and physical weight). Pop the lid and you’ll see the MOSFETs thermal pasted directly to its upper surface...........................

To push hard into higher MMG SPLs, the Chinese 35-watter’s hefty heatsink means the fan cooling of the RGi60 just isn’t needed. I can trigger the latter’s protection circuit when pushing The Stone Roses’ “Begging You” to increasingly higher SPLs. The RGi35ENR isn’t tripped up easily. That alone nets the Black Series unit an easy point in the game of quantitative one-upmanship....................

Several good photos of the heatsink in the link, along with the rest of the review (includes Maggies in use).

http://www.digitalaudioreview.net/2014/07/redgum-black-series-rgi35enr-integrated-amplifier-review/

With REDGUM’s permission I’m sharing internal shots of each amplifier.

 

[Blizzard]

I read this whole thread, and I'm bemused that the offenders love to play the role of the offended.

The tradition of professionals; scientists, doctors, lawyers, architects, musicians, engineers and so forth providing critical analysis and peer review of other's works is essential, and should not be censored by "walking on eggshells" as it was ironically stated.

So much drama, and to what point?

EDIT: The other thread is closed so I'll post this here.

http://www.digitalaudioreview.net/2014/07/redgum-black-series-rgi35enr-integrated-amplifier-review/


Several good photos of the heatsink in the link, along with the rest of the review (includes Maggies in use).

http://www.digitalaudioreview.net/2014/07/redgum-black-series-rgi35enr-integrated-amplifier-review/

No doubt. The way I see it is if your going to enter this industry (or any for that matter) you simply need to be able to backup and stand behind your product. If you are able to do that, then what do you have to worry about if you get a little criticism from time to time? You simply just have to explain why you engineered it that way. If your explanation doesn't hold water, then I guess you don't have what it takes to make it in today's highly competitive environment. Lick your wounds, and move on. And if you must, call the Dr Phil hotline for emotional support.

 

[JackD201]

So Redgum does use thermal paste as I suspected. Heat transfer with thermal paste can be, what 10x or more than bolting on? Seems the mystery to their not overheating is solved.

 

[Keith_W]

Big kudos to Andre for his apology. Takes a big man to do that. You have my respect, Andre.

However, Amir also has my respect. I disagree that he is egotistical and has dragged the tone of the forum down. I have found his contributions to be of immense value, and I would hate for him to leave. I think that as a moderator, he is a bit slow to react and is not aggressive enough (in fact, none of the moderators on this forum are!). But his posts, and his technical knowledge ... now here is a guy who is way smarter than I am, or could ever be.

 

[FrantzM]

So now ...
Can we get back to the original scheduled program?

 

[kach22i]

So Redgum does use thermal paste as I suspected. Heat transfer with thermal paste can be, what 10x or more than bolting on? Seems the mystery to their not overheating is solved.

I never heard of thermal paste before, so again I love learning about this stuff.

https://www.dowcorning.com/content/publishedlit/11-1712-01.pdf

Page 5, a section illustration explaining how it increases thermal transfer.

Page 6, illustrations showing heat sinks ABOVE the heat sources (because we all know that heat rises).

This topic sort of reminds me of a gable roof verses a butterfly roof. Both can work if executed properly but obviously there is a practical reason why we see so much more gable roofs.

http://www.houzz.com/ideabooks/2554330/list/dutch-gable-roof


https://rocknrollproblems.wordpress.com/2012/09/21/butterflies-crickets-and-our-roof/


From several years ago, I had some of this paste fail on me, nobody explained to me what it was and how to fix it.............I still need to fix this amp, and now I have an ideal how.

http://s184.photobucket.com/user/kach22i/library/Stereo?sort=3&page=3




From what I've been reading, they applied it on way too thick, thinner is better.

 

[Johnny Vinyl]

So now ...
Can we get back to the original scheduled program?

Let's hope so! I always look forward to the gear Andre introduces, even though he doesn't do vinyl.

 

[amirm]

So Redgum does use thermal paste as I suspected. Heat transfer with thermal paste can be, what 10x or more than bolting on? Seems the mystery to their not overheating is solved.

Hi Jack. Thermal compound is mandatory between the transistor and its heatsink to improve heat transfer as you mention. Even the most novice DIY amp builders know this. And certainly no commercial amp ships without some version of this.

The need for the compound is sharply increased in most amps that require electrical isolation of the output transistor body. The transistor metal tab connects to one of its pins which is usually going directly to power supply positive and negative rails. Without isolation you would simply short out the power supply! Some type of isolation is then necessary there in the form of mylar, etc. Once there, you now you have two surfaces that can reduce thermal transfer. Thermal compound therefore is used on both sides of the electrical isolator making for some messy job replacing the transistors!

I think the only time I have seen no paste was in cheap all-in-one hifi boxes of 1970s.

There was no mystery there anyway. The reason the unit doesn't overheat is due to its large heatsink relative to its modest output power. The concern we had was not that but rather the heat rising into the chassis and elevating the temps of the capacitor and thereby potentially shortening their life.

 

[DaveC]

That pic where the rectifier is supposed to be touching an electrolytic cap looks suspect to me, I do not believe they are touching. If you look down there is no solder pad for the rectifier right next to the cap. And it's not exactly esoteric knowledge that electrolytic caps shouldn't touch parts that get hot. IMO this is a good example of armchair engineering gone bad, and there were many more like it. I think some of the criticism was based on incorrect assumptions and it certainly went way too far, for example the guy who said everything would reach the same temps internally, this is just wrong. I don't think criticism should not be allowed, I just think maybe the people doing the criticizing need to be more thoughtful, and if you're not sure about something or simply aren't that knowledgeable on the subject there's no need to play expert and no need to post criticisms. Keep in mind what you are criticizing is built by a human being who probably owns a business related to it. Think about if that person was a good friend of yours, how would you go about criticizing the design? I think this is a much better approach vs seeing how many points you can make and looking for things to be critical about. People need to remember this is a public forum, say what you want in private, it's no big deal but different standards should be the norm for posts that are public for all to see.

 

[Johnny Vinyl]

 

[Andre Marc]

That pic where the rectifier is supposed to be touching an electrolytic cap looks suspect to me, I do not believe they are touching. If you look down there is no solder pad for the rectifier right next to the cap. And it's not exactly esoteric knowledge that electrolytic caps shouldn't touch parts that get hot. IMO this is a good example of armchair engineering gone bad, and there were many more like it. I think some of the criticism was based on incorrect assumptions and it certainly went way too far, for example the guy who said everything would reach the same temps internally, this is just wrong. I don't think criticism should not be allowed, I just think maybe the people doing the criticizing need to be more thoughtful, and if you're not sure about something or simply aren't that knowledgeable on the subject there's no need to play expert and no need to post criticisms. Keep in mind what you are criticizing is built by a human being who probably owns a business related to it. Think about if that person was a good friend of yours, how would you go about criticizing the design? I think this is a much better approach vs seeing how many points you can make and looking for things to be critical about. People need to remember this is a public forum, say what you want in private, it's no big deal but different standards should be the norm for posts that are public for all to see.

Dave, I could not have possibly been more eloquent than what you just posted. To say you "nailed" would be the understatement of the year.

Indeed, the need for some to flex their engineering muscles for the sake of it is crude. Insecurity can be a powerful thing, and wanting everyone to know
how "smart" you are leads to foolish posts and incorrect assumptions.

As you said, thoughtful, critical, comments are absolutely welcome.

Companies do no stay in business for decades in this hobby producing junk that blows up, overheats, or under performs significantly.

Either they go belly up, or they fix the problems along the way. The market really does work in retail.

 

[Blizzard]

I agree that it's not pleasant to have your products criticized, especially in a public form. However the way I look at it, a situation like this presents the perfect opportunity for the manufacturer to chime in and explain why their products are engineered the way they are. This will clear up any misconceptions from "armchair engineers" as well as reinforce to the public that not only is the product solidly engineered, the designer also stands behind his products.

Once I get my products to market, I can't wait for opportunities like this to arise.

 

[Andre Marc]

I agree that it's not pleasant to have your products criticized, especially in a public form. However the way I look at it, a situation like this presents the perfect opportunity for the manufacturer to chime in and explain why their products are engineered the way they are. This will clear up any misconceptions from "armchair engineers" as well as reinforce to the public that not only is the product solidly engineered, the designer also stands behind his products.

Once I get my products to market, I can't wait for opportunities like this to arise.

In fact, as I pointed out, Ian Robinson sent me a detailed overview of his design for Redgum amps, and it was met with total
and utter silence.