Hi Eva
that's very interesting what you are saying about SMD components, While I have found in some of the power area's SMD components do not work very well at all, but in other area's I have used them in, they have performed better that the hole through components, because of been able to have much shorter tracks between active and passive components, making the over all circuit much more compact.
Your comment about the bigger components such as filter caps,
Would you say if the PCB was kept rigid, such as mounting the main PCB with stand off's would this help the SMDs or are you saying that the filter caps could cause stress to the SMD's bacause of acoustic vibration or thermally been heated by the filter caps them self's?
I will keep in mind your extensive experience in this matter, thank you for sharing your knowledge Eva 🙂
Jeffry your chassis so far look's great what are you talking about 😉
that's very interesting what you are saying about SMD components, While I have found in some of the power area's SMD components do not work very well at all, but in other area's I have used them in, they have performed better that the hole through components, because of been able to have much shorter tracks between active and passive components, making the over all circuit much more compact.
Your comment about the bigger components such as filter caps,
Would you say if the PCB was kept rigid, such as mounting the main PCB with stand off's would this help the SMDs or are you saying that the filter caps could cause stress to the SMD's bacause of acoustic vibration or thermally been heated by the filter caps them self's?
I will keep in mind your extensive experience in this matter, thank you for sharing your knowledge Eva 🙂
Jeffry your chassis so far look's great what are you talking about 😉
Thermal cycling happens when you have power resistors or medium power SMD using the PCB as a heatsink and heating it substantially. This causes dilation and contraction. For example, I wouldn't do such a thing as a SMD VAS or output stage driver.
Vibration is a concern mostly in applications where the amplifier has to be moved (PA) or is mounted in a vehicle (car audio).
Heavy components are a concern when the PCB is subject to vibration or suffers any shock because bending can damage SMD. SMD should be placed far from heavy components and from any place where the PCB is expected to bend. Of course, PCB stand-offs can be used to keep bending under control (assuming that the case is rigid enough, otherwise they are a two-bladed sword).
Leads in thru-hole components do a great job protecting them from damage due to PCB bending or dilation/contraction (at least when you leave some lead lenght).
These are pretty obvious considerations, nothing special.
Vibration is a concern mostly in applications where the amplifier has to be moved (PA) or is mounted in a vehicle (car audio).
Heavy components are a concern when the PCB is subject to vibration or suffers any shock because bending can damage SMD. SMD should be placed far from heavy components and from any place where the PCB is expected to bend. Of course, PCB stand-offs can be used to keep bending under control (assuming that the case is rigid enough, otherwise they are a two-bladed sword).
Leads in thru-hole components do a great job protecting them from damage due to PCB bending or dilation/contraction (at least when you leave some lead lenght).
These are pretty obvious considerations, nothing special.
Eva: " ... SMD is fragile and component values drift with mechanical stress. In power applications, I prefer to use SMD only in daughter boards ... " " ... Thermal cycling happens when you have power resistors or medium power SMD using the PCB as a heatsink and heating it substantially ... Leads in thru-hole components do a great job protecting them from damage due to PCB [thermal and mechanical] bending ... "
Say, this is handy information to know !!
If you have links to appropriate reports / articles / postings ... it would be appreciated ...
"What every DIYer should know ..." 😀
Say, this is handy information to know !!
If you have links to appropriate reports / articles / postings ... it would be appreciated ...
"What every DIYer should know ..." 😀
Hi Ed, Eva
On the other hand I have used SMD quite extensively in my new products, from the input stages to the driver stages right before the output stage.
With no apparent problems at all, in fact it solved a number of issues I was having with some of the hole through components.
The other thing is I only use very high quality PCBs, that are very rigid and have at least 3 ounce copper foil and I use quite large amounts of the copper foil as heat sinks where needed such as VAS stages.
I have been using this technique in my NX400, NX500 and NX1000
amplifier modules with great success for over a year now.
and dozens of these modules are now in use with no reported issues.
Just the same I appreciate Eva's input as something to watch out for.
On the other hand I have used SMD quite extensively in my new products, from the input stages to the driver stages right before the output stage.
With no apparent problems at all, in fact it solved a number of issues I was having with some of the hole through components.
The other thing is I only use very high quality PCBs, that are very rigid and have at least 3 ounce copper foil and I use quite large amounts of the copper foil as heat sinks where needed such as VAS stages.
I have been using this technique in my NX400, NX500 and NX1000
amplifier modules with great success for over a year now.
and dozens of these modules are now in use with no reported issues.
Just the same I appreciate Eva's input as something to watch out for.
" ... use quite large amounts of the copper foil as heat sinks where needed ..."
Large copper plains or traces have an added benefit where possible = shielding. 😉
Large copper plains or traces have an added benefit where possible = shielding. 😉
Quite true Ed In my latest NX150 and NX400 module I am using
the bottom layer as a ground plane, directly underneath the SMD components on the topside. Works great and helps to get rid of noise other than generated by the active components them self's such as shot noise from the small signal transistors.
the bottom layer as a ground plane, directly underneath the SMD components on the topside. Works great and helps to get rid of noise other than generated by the active components them self's such as shot noise from the small signal transistors.
" ... [bigger traces & ground plains] Works great and helps to get rid of noise ..."
Ditto with heat (as you all know) and other interesting things like cost of manufacture (from reduced time in the chemical baths = more copper left behind) ... Its all feeds and speeds, don't you know ...
Sometimes with a little careful and judicious use of multiple ground traces (signal ground paths and chassis ground paths & plains, etc.), one can have all the benefits of almost no copper etched off (lower costs), better shielding, better thermal response and a significant improvement in signal to noise = all are win, win, win ... 😎
If you can get it so that the double sided boards have only a few plated through holes, then the "active side" can be done with a mill and the final time in chemicals can be reduced to an absolute minimum = quite ecological to produce as well as cost effective ... 😀
Ditto with heat (as you all know) and other interesting things like cost of manufacture (from reduced time in the chemical baths = more copper left behind) ... Its all feeds and speeds, don't you know ...
Sometimes with a little careful and judicious use of multiple ground traces (signal ground paths and chassis ground paths & plains, etc.), one can have all the benefits of almost no copper etched off (lower costs), better shielding, better thermal response and a significant improvement in signal to noise = all are win, win, win ... 😎
If you can get it so that the double sided boards have only a few plated through holes, then the "active side" can be done with a mill and the final time in chemicals can be reduced to an absolute minimum = quite ecological to produce as well as cost effective ... 😀
" ... Good Picture ..."
Not mine, but, yes they are quite good. Somewhere there should be a UTube video of the sessions as well ... but I don't know that link ...
Not mine, but, yes they are quite good. Somewhere there should be a UTube video of the sessions as well ... but I don't know that link ...
Jeffry
Even if they do go to pro audio which some of my audio modules
already have I will still be offering these modules at good prices.
My NX400 with combined PSU and loudspeaker protection is
going to be used in Chris Pelonis Signature series amplifiers.
due to be released in 1Q of 2008 www.pelonissound.com
So watch out for this as they are mated with his PSS110P loudspeakers.
I have a pair of these speakers here in my workshop.
and I have to say they would be the best sounding loudspeaker I have ever heard. I am not just saying this, it's true.
Chris recently had them with one of my amplifiers at this years October AES in New York.
Chris said that just about everyone that came to his booth were absolutley stunned with the sound quality. He had to get the people to move on so others could sit down and listen to them.
They just did not want to leave as they are that good to listen too.
Even if they do go to pro audio which some of my audio modules
already have I will still be offering these modules at good prices.
My NX400 with combined PSU and loudspeaker protection is
going to be used in Chris Pelonis Signature series amplifiers.
due to be released in 1Q of 2008 www.pelonissound.com
So watch out for this as they are mated with his PSS110P loudspeakers.
I have a pair of these speakers here in my workshop.
and I have to say they would be the best sounding loudspeaker I have ever heard. I am not just saying this, it's true.
Chris recently had them with one of my amplifiers at this years October AES in New York.
Chris said that just about everyone that came to his booth were absolutley stunned with the sound quality. He had to get the people to move on so others could sit down and listen to them.
They just did not want to leave as they are that good to listen too.
I own a Jeff Rowland Synergy II preamp which serves me well (except for the remote control which has stopped working; probably an internal fault in the pre).
The latest version is called Synergy IIi and has SMD components which is said to :
"In December of 2000, a new amplification board utilizing modern "small geometry" surface-mount technology gleaned from the Coherence II Preamplifier was designed and released for the Synergy II, lowering noise and distortion, and shortening signal paths dramatically."
Not much problems with thermal stress I guess and this pre isn´t intended to be moved a lot and no big currents like in a poweramp and it should and is connected to the mains all the time not even a stand by mode but luckily it´s consumption is low. (If the mains "is down" for more than a second, I have to reset a few settings to get the device working). It would be fun to compare my "old" model to the new one to get a cue of the importance of the SMD´s. Some reviews claim that this is a real improvement. Not a diy project to upgrade it though! 😉
http://www.jeffrowland.com/SynergyPreamp.htm
The latest version is called Synergy IIi and has SMD components which is said to :
"In December of 2000, a new amplification board utilizing modern "small geometry" surface-mount technology gleaned from the Coherence II Preamplifier was designed and released for the Synergy II, lowering noise and distortion, and shortening signal paths dramatically."
Not much problems with thermal stress I guess and this pre isn´t intended to be moved a lot and no big currents like in a poweramp and it should and is connected to the mains all the time not even a stand by mode but luckily it´s consumption is low. (If the mains "is down" for more than a second, I have to reset a few settings to get the device working). It would be fun to compare my "old" model to the new one to get a cue of the importance of the SMD´s. Some reviews claim that this is a real improvement. Not a diy project to upgrade it though! 😉
http://www.jeffrowland.com/SynergyPreamp.htm
" ... the Coherence II Preamplifier ... Not much problems with thermal stress I guess ..."
One would hope not = most pre-amps are low power draw and dissipation (as you say: "no big currents"), usually meaning that the components don't heat the boards too much. I would guess that the pre-amp makers are simply updating their technology = smaller can be better = better specs like intrusive noise, etc. " ... Some reviews claim that this is a real improvement. ..." wouldn't be surprised at all, at all ... 😎
One would hope not = most pre-amps are low power draw and dissipation (as you say: "no big currents"), usually meaning that the components don't heat the boards too much. I would guess that the pre-amp makers are simply updating their technology = smaller can be better = better specs like intrusive noise, etc. " ... Some reviews claim that this is a real improvement. ..." wouldn't be surprised at all, at all ... 😎
Yes, and on the other hand my big Class A power amp; LC Audio Patriot V 100 ; 2x100 W in 8 ohm (real Class A) big monster. Some years ago I lift the lid off and there were a few SMD here as well, if I recall right. It gets real hot and there must be much thermal "cycling" or stress in it.
I usually set it to Class AB (15 W Class A)when listening and keep it on in stand by in the meantime. The odd thing I have noted is that although full Class A sounds better, it´s possible to warm it in Class A and when it is hot reduce bias to Class AB ( by the flick of a switch ) and it will sound almost as good as in Class A for a long time.
So, it might be a fact (?) that transistors sound better when really warm. Some say MOS-FET:s should run hot to sound the best.
Resistors should have more thermal noise in case they are hot..
Please note, I can´t prove that eg power transistors should run hot to sound good, and the life of them would shorthen in case they are hot, on duty.
But suppose there is an ideal temperature for the output devices,
Bjt in this case, shouldn´t it be possible to keep them in this temperature range by some adaptive heat sink?
I usually set it to Class AB (15 W Class A)when listening and keep it on in stand by in the meantime. The odd thing I have noted is that although full Class A sounds better, it´s possible to warm it in Class A and when it is hot reduce bias to Class AB ( by the flick of a switch ) and it will sound almost as good as in Class A for a long time.
So, it might be a fact (?) that transistors sound better when really warm. Some say MOS-FET:s should run hot to sound the best.
Resistors should have more thermal noise in case they are hot..
Please note, I can´t prove that eg power transistors should run hot to sound good, and the life of them would shorthen in case they are hot, on duty.
But suppose there is an ideal temperature for the output devices,
Bjt in this case, shouldn´t it be possible to keep them in this temperature range by some adaptive heat sink?
" ... So, it might be a fact (?) that transistors sound better when really warm. Some say MOS-FET:s should run hot to sound the best. ..."
The Saint would know more about this ... but my "book learnin'" and work bench impression and is that most transistors and MOSFETs would certainly work more predictably and reliably when at a uniform long term temperature ... The metal (oxides of aluminum) in silicon transistors and MOSFETs responds predictably to temperature, resistance being uniform and linear at normal operating temperatures (usually from "room temp" up to around 60% of the point of "catastrophic thermal failure".) As for "sounding better", this would probably be more subjective ...
The Saint would know more about this ... but my "book learnin'" and work bench impression and is that most transistors and MOSFETs would certainly work more predictably and reliably when at a uniform long term temperature ... The metal (oxides of aluminum) in silicon transistors and MOSFETs responds predictably to temperature, resistance being uniform and linear at normal operating temperatures (usually from "room temp" up to around 60% of the point of "catastrophic thermal failure".) As for "sounding better", this would probably be more subjective ...
Hi Guys
Regarding Class A and transistors sounding better when they are hot.
I have built a number of Class A amplifiers and lots of AB amplifiers over the years.
And while the Class A designs did sound very good, I have some of my Class AB amplifiers that sound better.
I am not sure that Class A makes any amplifier sound better rather than a combination of good topology and Class A.
In much the same way good topology and class AB can make an amplifier sound equally as good.
It is very subjective and this topic has been debated a lot
over the years.
I have notice on many times that some amplifiers do sound better when they have been left on, most likely due to thermal distortion had settled after the amplifiers thermal cycle had stabilized.
Regarding Class A and transistors sounding better when they are hot.
I have built a number of Class A amplifiers and lots of AB amplifiers over the years.
And while the Class A designs did sound very good, I have some of my Class AB amplifiers that sound better.
I am not sure that Class A makes any amplifier sound better rather than a combination of good topology and Class A.
In much the same way good topology and class AB can make an amplifier sound equally as good.
It is very subjective and this topic has been debated a lot
over the years.
I have notice on many times that some amplifiers do sound better when they have been left on, most likely due to thermal distortion had settled after the amplifiers thermal cycle had stabilized.
Member
Joined 2002
The Saint said:
If you want you can lend me a pair of your aussie modules, and ill come pair them to my Aleph Mini A's 🙂
Hi Jason
Unfortunately I have sold out completely at this time of
NX150 base models and the NX150 synergy models.
I ended up selling heaps of these over the last 12 months or so.
I am currently working on a updated model that will
replace both the basic and synergy units.
I am toying with the idea of adding a loudspeaker protection circuit as well as on board power supply.
In much the same way as I have done with my NX400NL combo amplifier module, that I have been displaying on my web site at this time.
The only difference would be that most of the components would be SMD types and the overall size of the PCB at this stage is looking like 115mm x 55mm. The same current size of the NX150 module.
What do you think guys? What would you guys like to see added or taken away from these modules and what power level do you think is enough for most people? I have my own ideas, but I would like to here from all of you...
Unfortunately I have sold out completely at this time of
NX150 base models and the NX150 synergy models.
I ended up selling heaps of these over the last 12 months or so.
I am currently working on a updated model that will
replace both the basic and synergy units.
I am toying with the idea of adding a loudspeaker protection circuit as well as on board power supply.
In much the same way as I have done with my NX400NL combo amplifier module, that I have been displaying on my web site at this time.
The only difference would be that most of the components would be SMD types and the overall size of the PCB at this stage is looking like 115mm x 55mm. The same current size of the NX150 module.
What do you think guys? What would you guys like to see added or taken away from these modules and what power level do you think is enough for most people? I have my own ideas, but I would like to here from all of you...
Member
Joined 2002
The Saint said:
I think you should leave the speaker protection out 😛 i personally never use them, if the amp is built properly and is not abused no need for it, UNLESS you can find a extremely good relay i hate them 🙂
My amps don't use them. Id like to compare your amps to a aleph mini tho.
J'
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