I've just tried this and it doesn't buzz when I short its input to ground. The chassis is not grounded to mains earth, but the chassis is made from wood, except for the heat sink. The transformers are in a seperate chassis which is also made from wood.
What are your thoughts about this? Any other tests I could run?
Cheers,
Erik
Since it does not buzz when input's shorted on its own, is there any other power amp or integrated amp's/receiver's line input to connect the Mez and be sure there isn't any issue on its own too? I can see those big carbon 220R audio path 4 resistors very near to each other on your Mez. Can they be touching legs by accident?
disconnect your interconnect at the source end (Mezmerize) and connect it at the receive end (RevC). does touching the hot pin of the interconnect make much difference to the noise? Does touching the Barrel (cold) make much difference to the noise?
Does moving the interconnect cable around change the noise, i.e. is it a directional aerial.
I suspect the implementation of the input filters to the RevC may be partly responsible for what you are hearing.
Does moving the interconnect cable around change the noise, i.e. is it a directional aerial.
I suspect the implementation of the input filters to the RevC may be partly responsible for what you are hearing.
Good idea. I had to solder a new cable to connect it to a pair of active logitech speakers. Right now they are playing Nirvana's Lake of fire through the Mesmerize
So I guess it's the Myref that's causing the problem.
Cheers,
Erik
I have to say I'm a little anxious to try this because I don't want to hurt my speakers. The buzz I heard was really loud!
Right now I'm wondering what I can do to the Myref to cure this, since the Mesmerize seems ok (see my previous post).
Thanks a lot btw guys!
Cheers,
Erik
Mez powerup!
I finally finished my Mezmerize board and powered it up. Everything seems to check out OK. Power supply voltages are +10.03V and -9.57V, output offset voltages are -1.1mV and +0.3mV.
For current-setting resistors I used 3x61R9 0.5W on each side (Vishay RN65, selected for low temperature coefficient), so 20R63 effective resistance. I measured voltage drop across the resistor clusters of 1.640V and 1.716V, so current through them is 79.5/83.2 mA if my arithmetic is right.
For the LED's I used a mix of reds and yellows; the reds are supposed to have a Vf of 1.7V, the yellows 1.8V. When I measured them I found the reds were in the range 1.741-1.751, the yellows 1.950-1.963. I have not measured them in the actual circuit yet, but am curious how well the voltage refs match.
Here are some pics. You can see that I was goofing around with heat sinks a bit -- I had some TO220 heat sinks lying around so added them on the front of the MOSFETS, which looks ridiculous and probably accomplishes nothing. However, after about 20 minutes the heat sinks and the transistor cases all measured about 25C, so everything is nice and cool.
Now I need to order a case and a few other bits -- guess who forgot to order phono jacks? So I can't listen to it yet!
I finally finished my Mezmerize board and powered it up. Everything seems to check out OK. Power supply voltages are +10.03V and -9.57V, output offset voltages are -1.1mV and +0.3mV.
For current-setting resistors I used 3x61R9 0.5W on each side (Vishay RN65, selected for low temperature coefficient), so 20R63 effective resistance. I measured voltage drop across the resistor clusters of 1.640V and 1.716V, so current through them is 79.5/83.2 mA if my arithmetic is right.
For the LED's I used a mix of reds and yellows; the reds are supposed to have a Vf of 1.7V, the yellows 1.8V. When I measured them I found the reds were in the range 1.741-1.751, the yellows 1.950-1.963. I have not measured them in the actual circuit yet, but am curious how well the voltage refs match.
Here are some pics. You can see that I was goofing around with heat sinks a bit -- I had some TO220 heat sinks lying around so added them on the front of the MOSFETS, which looks ridiculous and probably accomplishes nothing. However, after about 20 minutes the heat sinks and the transistor cases all measured about 25C, so everything is nice and cool.
Now I need to order a case and a few other bits -- guess who forgot to order phono jacks? So I can't listen to it yet!
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Hi guys, thanks to ramallo we got a nice set of measurements for the Mezmerize you make here. They are taken on a Tektronix AM700 audio analyzer. I don't know more about measurement conditions, levels, etc. I just got them as shots. His Mez build measured. Thank you Suso. Great stuff.
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Yes, fully open.
I choose 200k because I'm using an F5 and is near (half).
If you want a specific test, let me know, I'll try to do.
Regards
Edit
: I have plans for do a dual DCB1 Hodrod on the same chassis (one for channel) (all symmetric) for control the studio monitoring. I'm very very impressed with the 200mA DCB1 sound. But in the new one I'll try to go to 500mA by using a power amp chassis (2 or 3 unit)
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Sounds like a hot plan.
Good luck and let us know.I have just put together an F5 - and I like it! What drew my attention to it was the simplicity of the circuit. My preamp has a lot of gain and my speakers are fairly efficient so there's more than ample volume.
Someone then recommended the DC B1, because the circuit is simple as the F5. Has anyone used a B1 with the F5? I'm a bit concerned that there won't be enough gain. It may mean that I go for new speakers.
Someone then recommended the DC B1, because the circuit is simple as the F5. Has anyone used a B1 with the F5? I'm a bit concerned that there won't be enough gain. It may mean that I go for new speakers.