Not rhodium, I can't afford it. I just checked the spot price, and it is almost $26,000/ounce. That is what is causing the increasing problem of catalytic converter theft around the country. People who leave their cars outside overnight rather than in the garage are waking up to some unfortunate surprises around here.
Those nice plug-in mounting pieces are available at Mouser, if I remember from earlier in this thread, and the part numbers are mentioned in one or more of the posts.
Hello,
Just finished my M2x and I think I have problems. I am a noob so please bear with me. Here are the readings:
V+ = 22.5 loaded
R13 = 605 mv Right, 620 mv Left
R14 = 604 mv R, 625 mv Left
DC offset cannot be set down to 0 with 47k R6 and 5k Rv1.
There is a thump turning the amp on and off on the right channel only. The amp makes music, but I am not sure if my numbers are fine. Thanks, Godspeed
Just finished my M2x and I think I have problems. I am a noob so please bear with me. Here are the readings:
V+ = 22.5 loaded
R13 = 605 mv Right, 620 mv Left
R14 = 604 mv R, 625 mv Left
DC offset cannot be set down to 0 with 47k R6 and 5k Rv1.
There is a thump turning the amp on and off on the right channel only. The amp makes music, but I am not sure if my numbers are fine. Thanks, Godspeed
To set DC offset to 0 you will need to either increase R7 or change values of R6 and Rv1 as per post #3.
I have built the standard verion of M2 and there is no thump when turning the amp on or off.
I found that reversing the brass stand offs that I use to mount my daughtercards with a nut on the bottom of the main board, and using the bolt from the top, makes it much easier to mount/unmount the cards. The hex screwdriver will hold the screws well, and a socket with nut from the side does not work as well. I also have damaged cards due to the socket size.
I think any number that multiplied by itself and divided by 8 or thereabouts results in a much smaller number of watts dissipated by the woofers coil. Something like 100 mV or less.
If you have sweet and tender altec 416 may need to be lower than if you have a b&c with big rectangular aluminum wire coils.
If you have sweet and tender altec 416 may need to be lower than if you have a b&c with big rectangular aluminum wire coils.
Isn't this a question about loudspeakers? Once you know the number it doesn't matter whether the DC offset comes from a DIY First Watt amp or an inexpensive amp on Banggood or a Krell amp in a too-hot room or a class D amp from ProfessionalAudioGearCheaper.com.
Hello,
I apologize for the confusion created by my question in my previous post. I am trying to determine if I can use my just completed M2x amp with a DC offset of -32 and -22 on the right and left channel respectively and not ruin my speakers. I cannot bring the offset down to 0. Ordered 37k resistors for R6 and 20K Bourn trimmers for RV1. Godspeed.
I apologize for the confusion created by my question in my previous post. I am trying to determine if I can use my just completed M2x amp with a DC offset of -32 and -22 on the right and left channel respectively and not ruin my speakers. I cannot bring the offset down to 0. Ordered 37k resistors for R6 and 20K Bourn trimmers for RV1. Godspeed.
You will have to live with uncertainty just as every other member of diyAudio lives with uncertainty.
If uncertainty is unacceptable to you, then you will have to personally measure each amplifier that you buy AND each loudspeaker that you buy. If their measured behavior is insufficient according to your opinion: throw it into the sewer. You can find SO MUCH BETTER behavior. Just work a little harder.
If uncertainty is unacceptable to you, then you will have to personally measure each amplifier that you buy AND each loudspeaker that you buy. If their measured behavior is insufficient according to your opinion: throw it into the sewer. You can find SO MUCH BETTER behavior. Just work a little harder.
I agree with Mark.
However, let’s make a very simple exercise and determine how much power 32mV represents that needs to be dissipated by your speaker.
In this case V^2 / R = P
32mV with an 8ohm speaker,
0.32^2 = .001024
.001024 / 8 = 0.00013W (If you have an 4 ohm speaker it’s double, or 0.00026W)
So the question to determine is can your speakers dissipate a DC current of 130 microwatts?
(Thirteen ten-thousandths of one watt)
However, let’s make a very simple exercise and determine how much power 32mV represents that needs to be dissipated by your speaker.
In this case V^2 / R = P
32mV with an 8ohm speaker,
0.32^2 = .001024
.001024 / 8 = 0.00013W (If you have an 4 ohm speaker it’s double, or 0.00026W)
So the question to determine is can your speakers dissipate a DC current of 130 microwatts?
(Thirteen ten-thousandths of one watt)
Black Forest Buffer Proto
Dirk told me he had issue with one channel that I do not understand.
So I asked him to send me a PCB so that I could build and check.
That was done this afternoon.
Only using nominal values with no trimming, DC offset was stable over 30 minutes at -6mV.
Bias went from 33mA to 35mA, hardly anything.
I ran it with a 10kHz sine wave for half and hour.
So no issue whatsoever.
The PNPs for the buffer did need some heat sinking.
I just grabbed one from my drawer, for convenience.
So the bug is not in the circuit or the PCB.
Patrick
.
I am more focused on the BlackForestBuffer of EUVL at the moment. Still some tweaks to do. But it plays music...
Dirk
Dirk told me he had issue with one channel that I do not understand.
So I asked him to send me a PCB so that I could build and check.
That was done this afternoon.
Only using nominal values with no trimming, DC offset was stable over 30 minutes at -6mV.
Bias went from 33mA to 35mA, hardly anything.
I ran it with a 10kHz sine wave for half and hour.
So no issue whatsoever.
The PNPs for the buffer did need some heat sinking.
I just grabbed one from my drawer, for convenience.
So the bug is not in the circuit or the PCB.
Patrick
.
