Coil and caps
Hi Quasi,
My first amp module is near finish and I have two questions
for you:
1. Can you please tell me how much turns to put in coil on the amp output and which wire to use?
2. I'm using MKT caps on input and output of the amp and all other ceramic. How this will afect the sound and what is the best choice of caps for the amp.
Thanks in advance!!!
Hi Quasi,
My first amp module is near finish and I have two questions
for you:1. Can you please tell me how much turns to put in coil on the amp output and which wire to use?
2. I'm using MKT caps on input and output of the amp and all other ceramic. How this will afect the sound and what is the best choice of caps for the amp.
Thanks in advance!!!
Hi Pejinm
I doubt the sound will be affected much. The main reason for using different capacitors is for the right value and for stability. Practical capacitors are resistive and inductive and in some situations can cause oscillations or ringing.
Capacitors C2, C3, C4 & C8 can be ceramic.
Capacitors C1, C5, C6, C9 & C10 should be poly or MKT.
C12 should be high voltage (200v) poly or MKT
I wound my output coil with 0.9mm enamelled wire. Just fit as many neat turns as you can. The actual inductance is not critical as this is just a filter against RF.
Please use inline resistors on the amp board supply leads when you first power your amp up. I start with 100 ohms (3 watt) for the first turn on and rough bias setting. All being well I then switch to 10 ohms for the final setting.
Cheers & good luck.
I doubt the sound will be affected much. The main reason for using different capacitors is for the right value and for stability. Practical capacitors are resistive and inductive and in some situations can cause oscillations or ringing.
Capacitors C2, C3, C4 & C8 can be ceramic.
Capacitors C1, C5, C6, C9 & C10 should be poly or MKT.
C12 should be high voltage (200v) poly or MKT
I wound my output coil with 0.9mm enamelled wire. Just fit as many neat turns as you can. The actual inductance is not critical as this is just a filter against RF.
Please use inline resistors on the amp board supply leads when you first power your amp up. I start with 100 ohms (3 watt) for the first turn on and rough bias setting. All being well I then switch to 10 ohms for the final setting.
Cheers & good luck.
Elso Kwak
Your post is quite detailed so I guess you may have concerns about;
- the slowness of contact closure because of the charge cct on the transistor base
or
- You don't like relays and maybe I should use a triac instead.
In practice the slowness of the contact closure does not seem to be a problem as the amps power supply is sufficiently charged when the contacts close, so the current through the contacts is lower. On power off the relay releases fairly quickly. I wondered about using a trigger to snap the relay in though...maybe one day.
I could use a triac based cct but I chose not to. No real reason apart from simplicity maybe. The relay cct has been in operation in an amp I built about 15 years without problems so far.
Cheers
Your post is quite detailed so I guess you may have concerns about;
- the slowness of contact closure because of the charge cct on the transistor base
or
- You don't like relays and maybe I should use a triac instead.
In practice the slowness of the contact closure does not seem to be a problem as the amps power supply is sufficiently charged when the contacts close, so the current through the contacts is lower. On power off the relay releases fairly quickly. I wondered about using a trigger to snap the relay in though...maybe one day.
I could use a triac based cct but I chose not to. No real reason apart from simplicity maybe. The relay cct has been in operation in an amp I built about 15 years without problems so far.
Cheers
Goodness me...
I am so embarrassed....It is of course spelt Neutral. English is not my native tongue ....but even so. I hope I spelt embarrassed correctly.....do I correct the cct and layouts?
I'm starting to shake ...what to do....the pain...please someone make it stop..!
I guess the 24v relays down under here are much the same as the ones up there.....or at least I think so.
.....still shaking ....
I am so embarrassed....It is of course spelt Neutral. English is not my native tongue ....but even so. I hope I spelt embarrassed correctly.....do I correct the cct and layouts?
I'm starting to shake ...what to do....the pain...please someone make it stop..!
I guess the 24v relays down under here are much the same as the ones up there.....or at least I think so.
.....still shaking ....
I agree with quasi, the circuit is fine in real life. Elso can talk when he posted the following circuit which I cannot even get to delay
An externally hosted image should be here but it was not working when we last tested it.
AC relay
Hi richie, That circuit is not a speaker relay but a delayed power on circuit to limit rush in current. The relay is an AC type, working on 230V AC. It's all original part of a Gas Ampzilla II power amplifier.
Hope this helps!
richie00boy said:I agree with quasi, the circuit is fine in real life. Elso can talk when he posted the following circuit which I cannot even get to delay
An externally hosted image should be here but it was not working when we last tested it.
Hi richie, That circuit is not a speaker relay but a delayed power on circuit to limit rush in current. The relay is an AC type, working on 230V AC. It's all original part of a Gas Ampzilla II power amplifier.
Hope this helps!
anatech said:
Yes this is a good one and a local friend uses it too. Sometimes though if the pre-amp is turned up and then the power amp is turned on, the power supply doesn't come up to enough voltage .....goodnight resistors. This could be resolved by using higher power resistors.
But as you say it does provide protection against faulty modules, short cct output etc. and would work well in intergrated units where the pre-amp can be controlled.
Cheers
V1.4 Board Varients
Hello All,
After quasi posted his V1.4 boards almost a year ago, I decided to take a crack using a graphics program to make two variants of the board. Skipping the long story, suffice to say I never posted them as my phone line, and how I have internet acess, was dead for 3 months in what was a full time job dealing Bell Canada's complete incompetencesoap opera to fix. While this was going on 20 other phone lines in our building were killed by Bell though more gross soap opera incompetence. I am just starting to catch up on thins a few months after the phone line is now working. I never posted those varients as I had no internet access due to my dead phone line.
Fast forward to now and quasi has posted very recently (Post #206 and Post #207) the V1.4 PCB images with DC Protection. Having of course no time =)) and still recovering from the stress and backlog of my dead phone line soap opera I thought I take another crack at making board variants. Well, after three days of effort I have what should be 3 varients of quasi's boards with DC Protection. Something really went strange in the editing of the four output device variant tracks image that resulted in that edit taking 8 hours!!! Oh well, software or operating system will be software and operating system
I wanted to put these in a PDF document either as all the variants in one, or at least each set (Top/Component view and tracks only view), but that has posed some PDF specific technical, and file size issues. So for now I will post 600DPI .PNG images until I have sorted out the technical issues of file size, links and bookmarks in the PDF file creation.
It would be great if other eyes can check these board variants to ensure I have not messed up quasi's fine boards. I have tried to be very careful in my edits, but as always please do your own checking before using these variants.
Regards,
John L. Males
Willowdale, Ontario
Canada
08 December 2005 18:54/19:03
Hello All,
After quasi posted his V1.4 boards almost a year ago, I decided to take a crack using a graphics program to make two variants of the board. Skipping the long story, suffice to say I never posted them as my phone line, and how I have internet acess, was dead for 3 months in what was a full time job dealing Bell Canada's complete incompetencesoap opera to fix. While this was going on 20 other phone lines in our building were killed by Bell though more gross soap opera incompetence. I am just starting to catch up on thins a few months after the phone line is now working. I never posted those varients as I had no internet access due to my dead phone line.
Fast forward to now and quasi has posted very recently (Post #206 and Post #207) the V1.4 PCB images with DC Protection. Having of course no time =)) and still recovering from the stress and backlog of my dead phone line soap opera I thought I take another crack at making board variants. Well, after three days of effort I have what should be 3 varients of quasi's boards with DC Protection. Something really went strange in the editing of the four output device variant tracks image that resulted in that edit taking 8 hours!!! Oh well, software or operating system will be software and operating system
I wanted to put these in a PDF document either as all the variants in one, or at least each set (Top/Component view and tracks only view), but that has posed some PDF specific technical, and file size issues. So for now I will post 600DPI .PNG images until I have sorted out the technical issues of file size, links and bookmarks in the PDF file creation.
It would be great if other eyes can check these board variants to ensure I have not messed up quasi's fine boards. I have tried to be very careful in my edits, but as always please do your own checking before using these variants.
Regards,
John L. Males
Willowdale, Ontario
Canada
08 December 2005 18:54/19:03
Re: V1.4 Board Varients
Top view of the two output device variant ... errrrr ..... shoot, darn... I was not aware the file size limit was just 100K, humm, any suggestions where/how can post or make available? Technology always presents surprises!!!!
Here is the list of files and file sizes in question I wanted to post.
268604 Dec 7 07:26 NchanMos350WithDCDetect-V1.4-1DevicePair-600dpi.png
292555 Dec 7 04:58 NchanMos350WithDCDetect-V1.4-2DevicePairs-600dpi.png
306283 Dec 7 03:32 NchanMos350WithDCDetect-V1.4-3DevicePairs-600dpi.png
318701 Dec 8 18:34 NchanMos350WithDCDetect-V1.4-4DevicePairs-600dpi.png
99356 Dec 7 06:10 NchanMos350WithDCDetect-V1.4-Tracks-1DevicePair-600dpi.png
107894 Dec 8 02:33 NchanMos350WithDCDetect-V1.4-Tracks-2DevicePairs-600dpi.png
103013 Dec 6 23:00 NchanMos350WithDCDetect-V1.4-Tracks-3DevicePairs-600dpi.png
122458 Dec 8 08:49 NchanMos350WithDCDetect-V1.4-Tracks-4DevicePairs-600dpi.png
John L. Males
Willowdale, Ontario
Canada
08 December 2005 19:15
keypunch said:
Top view of the two output device variant ... errrrr ..... shoot, darn... I was not aware the file size limit was just 100K, humm, any suggestions where/how can post or make available? Technology always presents surprises!!!!
Here is the list of files and file sizes in question I wanted to post.
268604 Dec 7 07:26 NchanMos350WithDCDetect-V1.4-1DevicePair-600dpi.png
292555 Dec 7 04:58 NchanMos350WithDCDetect-V1.4-2DevicePairs-600dpi.png
306283 Dec 7 03:32 NchanMos350WithDCDetect-V1.4-3DevicePairs-600dpi.png
318701 Dec 8 18:34 NchanMos350WithDCDetect-V1.4-4DevicePairs-600dpi.png
99356 Dec 7 06:10 NchanMos350WithDCDetect-V1.4-Tracks-1DevicePair-600dpi.png
107894 Dec 8 02:33 NchanMos350WithDCDetect-V1.4-Tracks-2DevicePairs-600dpi.png
103013 Dec 6 23:00 NchanMos350WithDCDetect-V1.4-Tracks-3DevicePairs-600dpi.png
122458 Dec 8 08:49 NchanMos350WithDCDetect-V1.4-Tracks-4DevicePairs-600dpi.png
John L. Males
Willowdale, Ontario
Canada
08 December 2005 19:15
Capacitor Questions
Hi,
I like to understand a bit about the capacitors. It seems there is some myth about capacitors and I like to have some help to clarify.
Of interest to me how the actual capacitance value of the bypass caps for the output devices is determined? Is it by math, trial and error and/or a designer's preference? I am not questiong the design value chosen, just the how it is determined. I have seen different N-Channel designs that will use 330uF, 100uF, 47uF et al for the bypass caps, and in some cases paralleled with a standard capacitor much like often used in digitial circuits. Some designs even use a set of bypass caps at each end of the output device rail. Can poepl enlighten me what factors, design considerations and /or formulas are used to determine what the values to suggest the ball park value or the actual value based on design criteria. Part of the reasoning for these questions is in case I find it useful to "tune" or experiment with values if an amp will be dedicated to a frequency band aka active crossover based system.
With respect to C11 and C13, could I use 120uF, 220uF, 470uF, 590uF or 680uF instead? If so any sonic impact and/or amp/power supply impact considerations?
It is clear the output devices are connected to the +-V rail which already have large filter caps. Why are C11/C13 type ca[acitors on the output device rails needed on the board? Is there not any need for the C11/C13 having to have the same current specifications as the power supply capacitors? Sorry for the questions, but I am trying to understand the why. I am not questioning estabilshed design practices.
If one had a choice in make of electrolytic capacitors to use for the amplifier proper (power supply is excluded from scope of question) from a list of Rubycon, Sprague, Elina, Capxon, Nichicon, Nippon, Teapo or Panasonic what order of choice would you choose and any special comments that may apply to the order or specific make.
It is also interesting to see some designs that will not use small bypass capacitors for a C11/C13 like capacitor. Is there any condition one must or must not use a small bypass capacitor?
Would a Maxcap 1uF poly be a good choice for C1? I often see a C1 set to 2.2uF. Is it 1uF in this design due to different resistor values on the input?
As an aside I did not see C7 mentioned in post #223. Is C7 a non-polar electrolytic?
Regards,
John L. Males
Willowdale, Ontario
Canada
09 December 2005 09:45
Hi,
I like to understand a bit about the capacitors. It seems there is some myth about capacitors and I like to have some help to clarify.
Of interest to me how the actual capacitance value of the bypass caps for the output devices is determined? Is it by math, trial and error and/or a designer's preference? I am not questiong the design value chosen, just the how it is determined. I have seen different N-Channel designs that will use 330uF, 100uF, 47uF et al for the bypass caps, and in some cases paralleled with a standard capacitor much like often used in digitial circuits. Some designs even use a set of bypass caps at each end of the output device rail. Can poepl enlighten me what factors, design considerations and /or formulas are used to determine what the values to suggest the ball park value or the actual value based on design criteria. Part of the reasoning for these questions is in case I find it useful to "tune" or experiment with values if an amp will be dedicated to a frequency band aka active crossover based system.
With respect to C11 and C13, could I use 120uF, 220uF, 470uF, 590uF or 680uF instead? If so any sonic impact and/or amp/power supply impact considerations?
It is clear the output devices are connected to the +-V rail which already have large filter caps. Why are C11/C13 type ca[acitors on the output device rails needed on the board? Is there not any need for the C11/C13 having to have the same current specifications as the power supply capacitors? Sorry for the questions, but I am trying to understand the why. I am not questioning estabilshed design practices.
If one had a choice in make of electrolytic capacitors to use for the amplifier proper (power supply is excluded from scope of question) from a list of Rubycon, Sprague, Elina, Capxon, Nichicon, Nippon, Teapo or Panasonic what order of choice would you choose and any special comments that may apply to the order or specific make.
It is also interesting to see some designs that will not use small bypass capacitors for a C11/C13 like capacitor. Is there any condition one must or must not use a small bypass capacitor?
Would a Maxcap 1uF poly be a good choice for C1? I often see a C1 set to 2.2uF. Is it 1uF in this design due to different resistor values on the input?
As an aside I did not see C7 mentioned in post #223. Is C7 a non-polar electrolytic?
Regards,
John L. Males
Willowdale, Ontario
Canada
09 December 2005 09:45