Well, you just tell them trafo is wery noisy, and you are building class A preamp (mention Pass - it'll help 😉), so you need a quiet trafo. Also, did you consider ordering toroidal trafo?
Today, I tried my BOZ on my father power amp, and it is noisy !!! When I pu my BOZ in my Zen V4, I don'T have humm probatly because the Zen V4 have so les gain than a normal amplifier. With my father system, the noise is very loud.
I begin to have serious problem with noise. I am discourage, it cost my many money and I don't have the performance that I want for the money I put.
Did somebody have problem with preamp noise ????
And my other transfo is at Plitron, they will make test on it, I am discourage.
I begin to have serious problem with noise. I am discourage, it cost my many money and I don't have the performance that I want for the money I put.
Did somebody have problem with preamp noise ????
And my other transfo is at Plitron, they will make test on it, I am discourage.
I have BOZ and BZLS, and i use speakers of roundabout 100dB/1W. I have no noise problem. The loudest "noise" i have is mechanical 50Hz from transformers - not out of the speakers. Keep distance between power supply and everything with signal. Care for ground. Use short and shielded cables.
I tried many thing without succes...... I don't think it is the cable... For test, I tried to connect the input of my amplifier directly before the pot of the preamp and the noise was very loud.
Gound the circuit change nothin in my case....
Gound the circuit change nothin in my case....
Since I have not seen any pictures in this whole thread, I might be wrong, in that case it might help others:
Circuits in preamps are very sensitive for noise pickup. Wires are like little antennae. I suggest you follow Peter Daniel's hint in rearranging the whole, build it nicely on protoboard or a PCB. Many people have good experiences with this preamp, so start surfing I-net for different approaches in building preamps. If it is ok, test different components. If something blows, there is often collitoral damage... 🙁
I expect you have little experiences with electronics? That's no big deal, I have allso little experiences. This helped a lot for me:
Work on protoboard (Experimental PCB). (easy, fast, and you can easy change components)
Build it with:
A) as short as possible signal path.
B) allways a star-like earthpoint. This point you can connect with eart-mains.
Allways when tweaking, change onely one thing per tweak, and test. (disconnect allways from mains!!!) I had a lot of problems, becouse I was not sistematicaly enough. (argh, my English...)
Write down the effects, this might help you in the future in gaining experiences fast.
Try to understand the circuit, you dont have to spell it out like it is a test or something (actually it is better, thoug pretty hard stuff in the beginning).
Good Luck!
Circuits in preamps are very sensitive for noise pickup. Wires are like little antennae. I suggest you follow Peter Daniel's hint in rearranging the whole, build it nicely on protoboard or a PCB. Many people have good experiences with this preamp, so start surfing I-net for different approaches in building preamps. If it is ok, test different components. If something blows, there is often collitoral damage... 🙁
I expect you have little experiences with electronics? That's no big deal, I have allso little experiences. This helped a lot for me:
Work on protoboard (Experimental PCB). (easy, fast, and you can easy change components)
Build it with:
A) as short as possible signal path.
B) allways a star-like earthpoint. This point you can connect with eart-mains.
Allways when tweaking, change onely one thing per tweak, and test. (disconnect allways from mains!!!) I had a lot of problems, becouse I was not sistematicaly enough. (argh, my English...)
Write down the effects, this might help you in the future in gaining experiences fast.
Try to understand the circuit, you dont have to spell it out like it is a test or something (actually it is better, thoug pretty hard stuff in the beginning).
Good Luck!
I don't use PCB. And I don't use wire ! The resisteance are directly one the cap or the transistor. The signal ise very short. The only wire I have, it is the ground, and for that, I use a big wire, like those two pass the ground in the wall for the 120 Vac. I think it is a #14 peace. Maybe this is a problem ??
It a boring, because my preamp is finish......
It a boring, because my preamp is finish......
Also, I use different board for my power supply and my circuit.... but this is not a problem I think !!!
I also don't think split sistems are bad - I have 3 boards: power, left, and right channel - no hum. I'm going to scan my pictures, so you can see weather you've done something wrong. Also, I'll put my trafo very close, to see weather it causes hum (it was 1-2m away when I tested it). Be back to you in a jiffy 😉
Arnold, you said the hum was onely there with one of the two powersupplies becouse of a faulty trafo?
And they are both the same in setup?
What was the reply of Plitron about your complaints?
Hum in trafos are often caused by lose windings. So if you can actually hear the trafo physically humming and you don't get another one under warranty, you might experiment with potting it in resin. Physical humming is in this way impossible...
And they are both the same in setup?
What was the reply of Plitron about your complaints?
Hum in trafos are often caused by lose windings. So if you can actually hear the trafo physically humming and you don't get another one under warranty, you might experiment with potting it in resin. Physical humming is in this way impossible...
The hum of the transfo is not physical, if I put my hear close to the transfo, there no noise. The problem, no noise with a transfo and noise with the other, with the same circuit...
Here what Plitron sent to me:
-------------------------------------------
Hello Gabriel,
We received the part but have not tested it yet. The type of testing we will be performing is a lab test and not a production line test. I am trying to get some time set aside from our lab people. I will get back to you by the end of the week.
Sincerely,
Gordon I. Campbell
Vice President
Quality
Here what Plitron sent to me:
-------------------------------------------
Hello Gabriel,
We received the part but have not tested it yet. The type of testing we will be performing is a lab test and not a production line test. I am trying to get some time set aside from our lab people. I will get back to you by the end of the week.
Sincerely,
Gordon I. Campbell
Vice President
Quality
What that mean:
When I turn of the preamplifier, the noise stay !
This want mean that the problem is not the power supply ???
Real ???
When I turn of the preamplifier, the noise stay !
This want mean that the problem is not the power supply ???
Real ???
Not necessarly...
You should test with and without the preamplifier connected to the amplifier.
You would have your answer right away.
By example, when I turn off mine, it continues to play for several seconds (10-15sec) until capacitors are discharged.
You should test with and without the preamplifier connected to the amplifier.
You would have your answer right away.
By example, when I turn off mine, it continues to play for several seconds (10-15sec) until capacitors are discharged.
Tieftoener: What is the resistor do you use at the inpout of the preamp ??? Me, I have a 100k, The sound and noise is loud at 1/3 of max....
Pardon me for barging in at this point, not having read most
of the previous posts, but the general recommendation is
that you use both input and output attenuators on both the
BOZ and SBOZ. Inputs of 25-50 Kohm pots and outputs of 5
-10 Kohm are typical. In actual practice, this has worked quite
well for the vast majority of systems.
Forgive me also for repeating for the 100th time:
With the output pots all the way up, set the input pots for the
highest level you are likely to want. Then use the output pots
for day-to-day volume controls.
You don't have to do it this way, of course, but it's a good start.
😎
of the previous posts, but the general recommendation is
that you use both input and output attenuators on both the
BOZ and SBOZ. Inputs of 25-50 Kohm pots and outputs of 5
-10 Kohm are typical. In actual practice, this has worked quite
well for the vast majority of systems.
Forgive me also for repeating for the 100th time:
With the output pots all the way up, set the input pots for the
highest level you are likely to want. Then use the output pots
for day-to-day volume controls.
You don't have to do it this way, of course, but it's a good start.
😎
Can the noise problem come from because the DC volatage is too high ???
The transformer is 30 + 30 = 60 .........* 1.4 = 84V
But my transfo have absolutly no "drop" I have about 93 V at the output of the rectifier bridge !
Maybe this is too much ???
Maybe there is too much volt on R1, 4.75k
The volt on R1 is 93-60= 33V 33/4750 = 7mA
this is a problem ???
The transformer is 30 + 30 = 60 .........* 1.4 = 84V
But my transfo have absolutly no "drop" I have about 93 V at the output of the rectifier bridge !
Maybe this is too much ???
Maybe there is too much volt on R1, 4.75k
The volt on R1 is 93-60= 33V 33/4750 = 7mA
this is a problem ???
Nobody know if it is a problem to have to much voltage at the input of the power supply of the bride of zen ???
I suppose you´re using the regulator (which brings voltage down to ~60V) as well!?
Then you just have to watch it´s dissipation and so the heatsink temperature.
Your caps should have high enough voltage rating also.
The main preamplifier will be supplied with the "original" 60V.
No changes or worries about that part.
Then you just have to watch it´s dissipation and so the heatsink temperature.
Your caps should have high enough voltage rating also.
The main preamplifier will be supplied with the "original" 60V.
No changes or worries about that part.
OK, next time I´ll think twice before I start writing.😉
Of course you have to watch dissipation of R1 also.
With 33V and 7mA it dissipates about 0.23W which is quite near to a standard 0.25W resistors. You could use a 1W there to get better sleep or use slightly higher value.
With 5.6k you should be on the safe side.
You get 93V with load or without? (just to be sure)
Cheers
Jens
Of course you have to watch dissipation of R1 also.
With 33V and 7mA it dissipates about 0.23W which is quite near to a standard 0.25W resistors. You could use a 1W there to get better sleep or use slightly higher value.
With 5.6k you should be on the safe side.
You get 93V with load or without? (just to be sure)
Cheers
Jens
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