And it fine tunes your attention to detail. Before I get flamed, let me explain.
I can check my work several times and still miss something or read something in an article and miss something intricate that from 10,000 ft seems to make sense, but there is more to it the deeper I get into the project. Wiring is one. Looks straight-forward, but my plans alway change after I start.
I f**k up a lot. I will in the future and refuse to be ashamed of it.
You are not alone.
Vince
That's interesting. Something is up there.
Do you have a fan on them? How is it ventilated?
Ok, when you are monitoring the bias during setup, what is your meter set to? Is it set to volts or millivolts DC? Is your multimeter analog or digital?
I'm trying to determine if you're at .060 volts instead of .60 volts.
Any chance of sending a photo of the amp board attached to the heat sink?
Here's what mine looks like and it gets hot. Never uncomfortable, except on one of the real hot/humid days in PA. Each heat sink is larger than 2"x9"x13".
using different amp boards but the HS are the same.
http://i145.photobucket.com/albums/r216/vdinenna/Audio Projects/DSCF0100.jpg
Vince
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I have to put my ear to the grill of the speaker to hear any hum, w/ no music playing of course.
The F5 was designed with a thermistor to help adjust the bias of the amp quicker. Some have listened to the F5 amp without the thermistor and overload protection and believe it sounds better. Do this at your own risk.
If you short the output or drive a speaker load that a low impedance, the amp might break, if the protection circuit is removed.
What's too low? 2 Ohms is low.
No fan, but I did use the thermal material instead of the mica and silicon that I had on when I had them swapped wrong. I wanted to just get them on. With the B1 there is no sound at all coming out of the idle speaker.
I admit that the meters are a pain when you have to dial in volts or millivolts, 2 to 200 ....But I think I am measuring it correctly. I wonder if I am just letting the mosfet get hotter than it needs to. I haven't touched it since it started working. Currently on vaca so I will look at that. That is nice looking amp.
Jan
F5 Help
Thanks Vince for your help. Got the second monoblock built but I was rough on the traces of the amp board. I got the readings pretty close on the dc offset but couldn't get it below ~30 mv. The measuremets across r11 were
.54 v. To get that, I adjusted the potentiometers in an assymetric way. Generates heat affter an hour but I can touch it for more than 10 seconds. Went ahead and attached it to a source and speakers. It made music. I was pleased but it is not an improvement from my current setup. Very pleased to have built it and determined to get it right. I have two more amp boards and will order parts. One Q. I get 27 volts out of the Peter Daniel PSU. I am using a 250 v 18-0-18 transformer, 2 hexfred bridges, two panasonic caps at 33,000uf, 8 .47 ohm 3 watt resistors and two 22,000uf mundorf caps. I expected to see 24 or 25 volts. Is this too an issue?
Thanks
Thanks Vince for your help. Got the second monoblock built but I was rough on the traces of the amp board. I got the readings pretty close on the dc offset but couldn't get it below ~30 mv. The measuremets across r11 were
.54 v. To get that, I adjusted the potentiometers in an assymetric way. Generates heat affter an hour but I can touch it for more than 10 seconds. Went ahead and attached it to a source and speakers. It made music. I was pleased but it is not an improvement from my current setup. Very pleased to have built it and determined to get it right. I have two more amp boards and will order parts. One Q. I get 27 volts out of the Peter Daniel PSU. I am using a 250 v 18-0-18 transformer, 2 hexfred bridges, two panasonic caps at 33,000uf, 8 .47 ohm 3 watt resistors and two 22,000uf mundorf caps. I expected to see 24 or 25 volts. Is this too an issue?
Thanks
F5 Volume
T
I notice that you comment on a volume issue on the F5 forum. When I set up the F5 monoblocks with the B1 and a Music Hall cd25.2 that I just got, the 50 ohm attenuator could not handle the volume. The first step was shockingly loud. Is that the attenuator? I also tried the MH with my B1 and an Adcom 555 and it too was too loud. I had to bring out my adcom pre. Sorry to ask such a studpid question, but as a newbie I just don't have the knowledge. Thanks Jan
T
I notice that you comment on a volume issue on the F5 forum. When I set up the F5 monoblocks with the B1 and a Music Hall cd25.2 that I just got, the 50 ohm attenuator could not handle the volume. The first step was shockingly loud. Is that the attenuator? I also tried the MH with my B1 and an Adcom 555 and it too was too loud. I had to bring out my adcom pre. Sorry to ask such a studpid question, but as a newbie I just don't have the knowledge. Thanks Jan
do you know the RMS output voltage on the CDP. It's probably over 2.0v.
I think the B1-F5 is a high gain combo with sensitive speakers, (I have lowther as midrange). I wouldnt go too far either wat with the feedback resistors, it will change the performance of the amp at a certain point.
Did you use a linear or log pot on the B1?
I think the B1-F5 is a high gain combo with sensitive speakers, (I have lowther as midrange). I wouldnt go too far either wat with the feedback resistors, it will change the performance of the amp at a certain point.
Did you use a linear or log pot on the B1?
2.5v out is the problem. Makes the CD player have balls, but delivers a lot of output. You could add a resistor or l-pad on the output of the CD player or input of F5, or swap out the 100 ohm power resistors, maybe to 50-75 ohms.
If you use multiple sources, you I dont advice altering the amps gain to account for a HOT CDP out.
If you use multiple sources, you I dont advice altering the amps gain to account for a HOT CDP out.
I'm not sure how you're getting 27V out of an 18-0-18 transformer, but I'm
running an F5 off a 25-0-25 transformer ~35Vdc out without a problem. I'm
planning on switching back to a 18-0-18 when the shipment comes.
On setting the offset: I've found the easiest way to do that is once you are
close to 0.6V on R11 and R12 put your meter across the output and tweak
one of the pots until you get 0V. You shouldn't have to go very far, but you
can go back a check to make sure you still have the 0.6V you want. I think
30mV is reasonable anyway.
F5 Problems
Vince: no, I thought I would add a couple of resistors to the right and left sides of the attenuator. I had to take out the B1 and insert an adcom pre to listen.
Ryssen: you are right. It's 18 v but dual secondaries. I think that is how you describe it.
It is unloaded as I am checking the power supply measurements for both monoblocks.
Fritz: you are right after I wrote that I thought I mispoke (18-0-18) I like that description of the adjustment process. Thanks
Tea-Bag: That is terrific information.
Thanks all.
Vince: no, I thought I would add a couple of resistors to the right and left sides of the attenuator. I had to take out the B1 and insert an adcom pre to listen.
Ryssen: you are right. It's 18 v but dual secondaries. I think that is how you describe it.
It is unloaded as I am checking the power supply measurements for both monoblocks.
Fritz: you are right after I wrote that I thought I mispoke (18-0-18) I like that description of the adjustment process. Thanks
Tea-Bag: That is terrific information.
Thanks all.
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