front panel "art"
barely art. But I slapped together a vector art thing that I used for the front panel. I'll see if I can attach files here.
The "stop font" STOP.tff is included here as well. Not sure if that's a copy right thing, I'm 100% sure I didn't pay for it, and I didn't get too crazy with acquiring it either, so I think it'll be okay.
It didn't take the tff files, but they're in the ZIP, so that should be fine. Adobe Illustrator is what I used.
Hope this makes shortcuts for someone!
barely art. But I slapped together a vector art thing that I used for the front panel. I'll see if I can attach files here.
The "stop font" STOP.tff is included here as well. Not sure if that's a copy right thing, I'm 100% sure I didn't pay for it, and I didn't get too crazy with acquiring it either, so I think it'll be okay.
It didn't take the tff files, but they're in the ZIP, so that should be fine. Adobe Illustrator is what I used.
Hope this makes shortcuts for someone!
Attachments
Very nice, Drew! Lining up with a capital Y is so awkward, but this looks good. I'm not sure exactly how I'm going to finish my front panel yet. I got silver to have the options of the pretapped mounting holes, but I'm considering buying some self-etching primer and maybe a nice matte black to match the rest of the chassis. I might print some letters out on my wife's Cricut to make a positive stencil, not sure. I think the slightly raised silver letters on the black panel would look really nice if I did it right, but when it comes to me and painting that's a pretty big if haha.
If you are going to go to the trouble of painting the front panel I suggest you use an automotive rattle can spray paint rather than a Rustoleum or Krylon rattle can. I have found that the automotive paint will give you a much harder and more durable finish. It costs a bit more but is worth it IME.
Self etch primer is a good starting point and I have used it a lot on larger projects, but have been disappointed in the durability of non automotive finishes.
Self etch primer is a good starting point and I have used it a lot on larger projects, but have been disappointed in the durability of non automotive finishes.
Totally, thanks! I don't have any scrap aluminum to test on, but I could test on the back side. To be honest I'll probably just send it.
Link should be jumpered to ground. Output is from OP, there are three pads, one for speaker, one for N & P channel.
Front heat sinks OK, move thermistor to the plastic of MOSFET to prevent short circuit.
Look for bias procedure in beginning of thread.
to Nikwatt #6449
Good morning Nikwatt,
you've asked for the correct bias. This depends on your configuration
of your F5T.
If I am allowed to give you an advice:
Don' t bias it to the full amount of bias you want to reach at start-up.
I would bias to anywhere between 250mV to 300mV over one bias - resistor.
If you got it there ( I think you will need 30 minutes to an hour to get there),
let it cook (let the heatsinks become warm - the Mosfets will heat them for sure!- but slowly).
Always have an eye on your DMMs - where is your DCoffset at speakeroutput- it will drift up and down alittle bit (a few mV) - that is normal in the F5T. But take care that it is not running away (below 50mV is all o.K.) more than 100mV - this means - could become dangerous.
You know the procedure to bias it up? dial up pot 1 (since you see some DCoffset at speakerout/ max.50mV - then dial up pot2 - since you get the DCoffset at speakerout back close to 0mV. Wait a short while.
Same procedure again: pot 1 up - till 50mV DCoffset at speakerout
pot2 up - till getting back close to 0mV DCoffset
...
The other two DMMs show you your bias over one N-ch-Mosfet
and over one P-ch-Mosfet.
The voltage you measure over the bias resistors will be not exactly
the same for the N-ch-bias and the P-ch-bias. This is dependent on how good your Mosfets are matched. I think they will be a few mV different.
I think more important than the value of your bias in mV is how hot this
baby gets. Not more than 50°C on the heatsinks - or bias down.
And as higher you get with your bias, as more sensitive the F5T reacts on each little increment of a turn on the pots1/2 - so, no wild screwing on the trimpots!
And read the very good bias instruction in post#2 again. My one is the most
simplified way how I can explain the 'bias-game'.
I wish you success!
No smoking F5T please...
I like this amp
Greets
Dirk
Good morning Nikwatt,
you've asked for the correct bias. This depends on your configuration
of your F5T.
If I am allowed to give you an advice:
Don' t bias it to the full amount of bias you want to reach at start-up.
I would bias to anywhere between 250mV to 300mV over one bias - resistor.
If you got it there ( I think you will need 30 minutes to an hour to get there),
let it cook (let the heatsinks become warm - the Mosfets will heat them for sure!- but slowly).
Always have an eye on your DMMs - where is your DCoffset at speakeroutput- it will drift up and down alittle bit (a few mV) - that is normal in the F5T. But take care that it is not running away (below 50mV is all o.K.) more than 100mV - this means - could become dangerous.
You know the procedure to bias it up? dial up pot 1 (since you see some DCoffset at speakerout/ max.50mV - then dial up pot2 - since you get the DCoffset at speakerout back close to 0mV. Wait a short while.
Same procedure again: pot 1 up - till 50mV DCoffset at speakerout
pot2 up - till getting back close to 0mV DCoffset
...
The other two DMMs show you your bias over one N-ch-Mosfet
and over one P-ch-Mosfet.
The voltage you measure over the bias resistors will be not exactly
the same for the N-ch-bias and the P-ch-bias. This is dependent on how good your Mosfets are matched. I think they will be a few mV different.
I think more important than the value of your bias in mV is how hot this
baby gets. Not more than 50°C on the heatsinks - or bias down.
And as higher you get with your bias, as more sensitive the F5T reacts on each little increment of a turn on the pots1/2 - so, no wild screwing on the trimpots!
And read the very good bias instruction in post#2 again. My one is the most
simplified way how I can explain the 'bias-game'.
I wish you success!
No smoking F5T please...
I like this ampGreets
Dirk
ready for first power up
Just wondering if anyone can look my build over, and give me recommendations, also if you see anything incorrect.
I am looking for recommendations on mounting the LEDs so they shine nicely through the physical hole drilled out in the 10mm aluminum front bezel.
I pulled all the washers off the FETs, pretty sure they're not really needed, and in some cases, get in the way of the thermistors.
A video looking around the case:
Shared album - Drew Kerlee - Google Photos
google photo album of the build
Shared album - Drew Kerlee - Google Photos
thanks in advance!
Just wondering if anyone can look my build over, and give me recommendations, also if you see anything incorrect.
I am looking for recommendations on mounting the LEDs so they shine nicely through the physical hole drilled out in the 10mm aluminum front bezel.
I pulled all the washers off the FETs, pretty sure they're not really needed, and in some cases, get in the way of the thermistors.
A video looking around the case:
Shared album - Drew Kerlee - Google Photos
google photo album of the build
Shared album - Drew Kerlee - Google Photos
thanks in advance!
Attachments
This depends a bit on what you mean with „shine nicely“.
- if you want them to gently glow and be visible from more or less every view angle, you should use a kind of a lens of sorts (think light-conductive rod of plexiglass), and use it to adjust the lights jut (position) on the front plate +- 0.5 mm ...
- use something like that, tweak for positioning: https://www.mouser.ch/Optoelectronics/LED-Indication/LED-Lenses/_/N-b1d1r?P=1z0wugs
first power up: voltage across speaker outs, bulb on
Just wanted to check if this was normal. I think I'm supposed to be getting about nothing (in the mV range) over the speaker outputs +/- ??
As I dialed up the variac, to 44V, one channel at a time. On both channels (seperatley) I was getting a half volt on the output,
R-channel
44V variac, 1.431VDC on PSU out, 0.495V across speaker out +/-, bulb glowing
L-channel
44V variac, 1.435VDC on PSU out, 0.493V across speaker out +/-, bulb glowing
Input RCAs are not shorted. Nothing is hooked up to speaker terminals, except the multi-meter. I dialed P1 and P2 as close to zero as they'd go, which was around 1.1ohm (across TP1-2 and TP3-4 on FE board).
Do I have a short? Am I measuring something incorrectly? I'm glad the boards had the same numbers - I wired them the same, even if incorrect somewhere.
In 6L6 procedure, he mentions "Place voltmeters across TP of output board, one on N-channel, one on P channel." What exactly is the TP of output put board? There's a TP1, 2, and 3.
Just wanted to check if this was normal. I think I'm supposed to be getting about nothing (in the mV range) over the speaker outputs +/- ??
As I dialed up the variac, to 44V, one channel at a time. On both channels (seperatley) I was getting a half volt on the output,
R-channel
44V variac, 1.431VDC on PSU out, 0.495V across speaker out +/-, bulb glowing
L-channel
44V variac, 1.435VDC on PSU out, 0.493V across speaker out +/-, bulb glowing
Input RCAs are not shorted. Nothing is hooked up to speaker terminals, except the multi-meter. I dialed P1 and P2 as close to zero as they'd go, which was around 1.1ohm (across TP1-2 and TP3-4 on FE board).
Do I have a short? Am I measuring something incorrectly? I'm glad the boards had the same numbers - I wired them the same, even if incorrect somewhere.
In 6L6 procedure, he mentions "Place voltmeters across TP of output board, one on N-channel, one on P channel." What exactly is the TP of output put board? There's a TP1, 2, and 3.
Attachments
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I have no specific part numbers to give you. You really just need to verify the same pin out and that the part substituted has at least the same voltage and current ratings.
If you are having trouble getting the required discrete diodes then you can go to a simple off board 35 amp bridge rectifier, which should be obtainable just about anywhere. I used those in my F5V3 monoblocks and they work just fine.