Fit interference attenuators.
P.Daniel seems to forego everything that he thinks is not needed for basic audio amplification.
Try 47pF across the RCA input socket.
Try 100r+1nF at the PCB input.
These will give you a 2pole roll-off of the Radio frequencies.
Try adding an interference suppressor to the lamp. Across the lamp rather than across the switch. Interference is best attenuated at source and all equipment is supposed to be tested to comply with COMPULSORY RF attenuation standards.
P.Daniel seems to forego everything that he thinks is not needed for basic audio amplification.
Try 47pF across the RCA input socket.
Try 100r+1nF at the PCB input.
These will give you a 2pole roll-off of the Radio frequencies.
Try adding an interference suppressor to the lamp. Across the lamp rather than across the switch. Interference is best attenuated at source and all equipment is supposed to be tested to comply with COMPULSORY RF attenuation standards.
Transformers shouldn't have any effect on pop. is your output ground also connected to the chassis? What is the DC offset?
I did it already, and used a ceramic 220pF like this FK28C0G2A221J TDK | Mouser
it worked. I don't get pops when switching lamps and other appliances.
it worked. I don't get pops when switching lamps and other appliances.
Began the construction lately of my 3875 amp. Instead of asking Peter via email lie I did, I figured that posting questions here is more appropriate, since it can be shared with everyone.
I'm Getting there in regards to getting all the parts I need/want for the project. Been browsing a lot here to answer most of what I need to know (mostly with success! thanks everyone!)
A few little things...
1- Been looking for a quality input selector. I read on this thread about it, ubt just to be sure : would this fit the bill for a stereo lm3875 : More Information Page
2- I would like to switch the output between a 6.5mm headphone jack and the binding posts via a 2P2T off-on-off toggle switch. Any consideration in regards to quality of switch and jack I should look for? Its stressed out that line level inputs need good contact surface (gold plating). Would it be the same for outputs where the signal is amplified?
headphone jack ground connects directly to OG on both amp board?
3- Is it possible to install a sub output of some kind? I searched quite a lot and did not quite found information guiding me in this endeavor.
4- How does on implement the cl-60 thermistor exactly in the system?
THanks in advance for helping me here!
I'm Getting there in regards to getting all the parts I need/want for the project. Been browsing a lot here to answer most of what I need to know (mostly with success! thanks everyone!)
A few little things...
1- Been looking for a quality input selector. I read on this thread about it, ubt just to be sure : would this fit the bill for a stereo lm3875 : More Information Page
2- I would like to switch the output between a 6.5mm headphone jack and the binding posts via a 2P2T off-on-off toggle switch. Any consideration in regards to quality of switch and jack I should look for? Its stressed out that line level inputs need good contact surface (gold plating). Would it be the same for outputs where the signal is amplified?
headphone jack ground connects directly to OG on both amp board?
3- Is it possible to install a sub output of some kind? I searched quite a lot and did not quite found information guiding me in this endeavor.
4- How does on implement the cl-60 thermistor exactly in the system?
THanks in advance for helping me here!
HOw does one install this little capacitor? postive pin in direction of the chip? Is there a polarity? And If I install it at the rca input ?
Use an attenuated output for the headphones.
A 100r:1r will cut the volume by 40dB and not blow up your headphones if you had left the vol pot at max. This gives the headphones a source impedance of ~1ohm. If you phones need a higher source impedance, you can increase the resistor values.
Polarised electrolytics need to be installed with reference to any DC on the cap pads/pins.
All bi-polar and non polar capacitors can be installed either way around.
Just measure the voltage across the pads to find out which way to orient a polarised electro.
Where did you find this reference to a CL60? Is it in a sch, or in a BoM?
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Thanks Andrew, will look down that way for the headphone.
It's post #74, from this thread right here!
It's post #74, from this thread right here!
Peter Daniel's statement is oft repeated on this Forum.
Has anyone including Pass ever tested that arrangement?
Has any Member posted results of such a test?
Would you like to place your life on something that is of dubious origin?
Until some Member posts a good and reliable test, I cannot recommend a CL60 as the sole replacement for a direct MAG to Chassis Safety connection !
You struck my curiosity here. And you have btought up the issu of electrical safety more than once on this thread. what are those two things you mentionned in this quote? What are Commercial amp (wich I assume are completely safe) have in this regard that Peter's recommendation has'nt ?
I normally use those rotary switches in the Integrated Amp and they work perfectly fine: More Information Page
If I want something better, I use Greyhill: 71BD30-01-2-AJN Grayhill Inc. | Switches | DigiKey
You can find nice silver contact TOCOS toggle switches at percyaudio.com
Assuming you are using some sort of volume control, headphone output can be connected directly to the Gainclone amp output. That option has been discussed previously and I've built some very successful headphone only amplifiers using the kit discussed here:
http://www.diyaudio.com/forums/headphone-systems/62828-lm3875-headphone-amp-another-try.html
http://www.diyaudio.com/forums/audi...kit-building-instructions-68.html#post2432391
The sub output can be taken right after volume control. I did it on few ocasions and it worked fine.
I never used CL60 thermistor in Gainclone, the information I posted earlier was just an example of how others deal with an issue of ground breaking circuit.
When I build an amp for myself, I just use a single 10 ohm resistor between circuit ground and chassis.
For other options, I leave it to AndrewT to enlighten you all, he does perfectly fine job here, although he tends to complicate things a bit more then really needed. ;-)
Never place a sole resistor in the Fault Current route. This route is what blows the mains fuse if there is a catastrophic mains failure that leaks out to the internal components. This fault current can exceed 1kA. A resistor will simply explode !
The only alternative to a direct robust wire connection from MAG to Chassis that I can recommend is the dual inverse parallel Power Diode based on a 25A or 35A bridge rectifier. I have tested this Disconnecting Network. It works.
If some or all of my explanations are too complicated then it's up to the Member to ask some further question/s
dual = two
parallel = two side by side both connected at each end
Power Diode = a diode that is used for Power rectification.
Inverse = reverse to some other. In this case the parallel pair of diodes has one that is reversed relative to the other.
If you search for "inverse parallel" you will find it mentioned/recommended many times.
Search found 450 posts using the term.
In one post that I remember seeing, the poster incorrectly wrote "back to back diodes". I know that back to back diodes pass no current. This will not voltage limit in event it is asked to pass a current.
parallel = two side by side both connected at each end
Power Diode = a diode that is used for Power rectification.
Inverse = reverse to some other. In this case the parallel pair of diodes has one that is reversed relative to the other.
If you search for "inverse parallel" you will find it mentioned/recommended many times.
Search found 450 posts using the term.
In one post that I remember seeing, the poster incorrectly wrote "back to back diodes". I know that back to back diodes pass no current. This will not voltage limit in event it is asked to pass a current.
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So-called "loop breaker circuits" are discussed on Rod Elliott's site:
Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
Deeply troubling meter readings...
I hooked up an Amplimo 120 VA 2x22v transformer up to the provided diode boards and proceeded measuring the voltage as described in the manual. However, the readings I get are wildly off the mark indeed:
V- PG- = -138.0
V+ PG+ = 138.0
In both instances I connected the con lead of the multimeter to the PG side of the board. I had no readings at setting my multimeter to 20v DC, but had these at 200v.
What is going wrong here? Thanks from a total n00b summoning forces beyond his abilities.
I hooked up an Amplimo 120 VA 2x22v transformer up to the provided diode boards and proceeded measuring the voltage as described in the manual. However, the readings I get are wildly off the mark indeed:
V- PG- = -138.0
V+ PG+ = 138.0
In both instances I connected the con lead of the multimeter to the PG side of the board. I had no readings at setting my multimeter to 20v DC, but had these at 200v.
What is going wrong here? Thanks from a total n00b summoning forces beyond his abilities.