[Bhk1004]

feel like most people make these on their own. The few I have seen were all self soldered.

 

[purk]

How much does it cost to commission a build for the CFA3? Thanks.

 

[decur]

How much does it cost to commission a build for the CFA3? Thanks.

It all depends on the parts chosen
contact ”dukei”
he can price it out for you.
miroslav was excellent to work with,and did a really nice job building mine.

 

[MN8372]

Hi all - I took delivery of a CFA3 yesterday from Dukei (thanks to the good words from the people on this thread). Awesome service and great guy to deal with.

The amp is a keeper - I knew that from the first 20 seconds.

Miroslav said I should give it a couple of days to let it settle down which I will do.

But it’s an absolute beast of a thing with so much more punch, detail and clarity than I’m used to. Just need to make sure the kids don’t mess with it and blow it up by plugging and unplugging headphones whilst it is turned on… I might stick a nuclear warning sign on it. Seems appropriate.

 

[migo]

Hi all - I took delivery of a CFA3 yesterday from Dukei (thanks to the good words from the people on this thread). Awesome service and great guy to deal with.

The amp is a keeper - I knew that from the first 20 seconds.

Miroslav said I should give it a couple of days to let it settle down which I will do.

But it’s an absolute beast of a thing with so much more punch, detail and clarity than I’m used to. Just need to make sure the kids don’t mess with it and blow it up by plugging and unplugging headphones whilst it is turned on… I might stick a nuclear warning sign on it. Seems appropriate.

I'm really curios why is plugging/unplugging headphones so dangerous for this AMP? (off course not playing music on 100% volume situation Is it by design? I always plug ma HP last to my chain, when all is powered on and connected to protect them. I'm very interested in this amp but this is a bit strange. Thank you very much!

 

[Bhk1004]

Do people really turn off and on their amp swapping headphones? I do pause it, and turn the volume down before swapping. Volume down is mainly cause of different volume/power level depending on the headphone.

 

[Beefy]

Do people really turn off and on their amp swapping headphones? I do pause it, and turn the volume down before swapping. Volume down is mainly cause of different volume/power level depending on the headphone.

The problem with something like the CFA (and in the past, also the B22) is that these amps have vanishingly low output impedances, very high voltage rails, and no current limiting circuitry. Combine that with a shorting TRS jack, which can potentially allow literal amperes of current to run through the output stage. This is very bad.

So, yes volume down to zero when switching phones, this is pretty much essential. Turning off the amp completely when switching phones probably isn't necessary, but it also isn't silly. Use of a non-shorting jack makes sense as well - I've often considered switching to 4-pin XLR for everything - even for unbalanced phones and unbalanced amps (quite a lot of people already do this).

 

[paradoxper]

The problem with something like the CFA (and in the past, also the B22) is that these amps have vanishingly low output impedances, very high voltage rails, and no current limiting circuitry. Combine that with a shorting TRS jack, which can potentially allow literal amperes of current to run through the output stage. This is very bad.

So, yes volume down to zero when switching phones, this is pretty much essential. Turning off the amp completely when switching phones probably isn't necessary, but it also isn't silly. Use of a non-shorting jack makes sense as well - I've often considered switching to 4-pin XLR for everything - even for unbalanced phones and unbalanced amps (quite a lot of people already do this).

This will require further elaboration. Switching from XLR output to single ended output when the amp is on will burn the output transistors.

@Dukei please provide the full context.

 

[Bhk1004]

This will require further elaboration. Switching from XLR output to single ended output when the amp is on will burn the output transistors.

@Dukei please provide the full context.

I mean... you say this but I did this without issue for over a year. Of course with song paused and volume reduced.

 

[Beefy]

This will require further elaboration. Switching from XLR output to single ended output when the amp is on will burn the output transistors.

@Dukei please provide the full context.

That's not even remotely what I meant. I meant in most circumstance, don't install a TRS connector in the amp at all. It's not a great connector for any situation that can pass a lot of current.

I mean... you say this but I did this without issue for over a year. Of course with song paused and volume reduced.

Song paused and volume reduced should be fine. Just don't want to risk a potential short while there is music playing.

 

[Dukei]

The problem with something like the CFA (and in the past, also the B22) is that these amps have vanishingly low output impedances, very high voltage rails, and no current limiting circuitry. Combine that with a shorting TRS jack, which can potentially allow literal amperes of current to run through the output stage. This is very bad.

So, yes volume down to zero when switching phones, this is pretty much essential. Turning off the amp completely when switching phones probably isn't necessary, but it also isn't silly. Use of a non-shorting jack makes sense as well - I've often considered switching to 4-pin XLR for everything - even for unbalanced phones and unbalanced amps (quite a lot of people already do this).

This summarizes it very well. Although I would recommend powering off the amp when plugging/unplugging hp, doesn't take long to do it.
I have done some configurations with speaker terminals. In that case, it would be alright to turn the volume down and use the headphone/speaker switch while the unit is on.

I always plug ma HP last to my chain, when all is powered on and connected to protect them.

You are probably trying to save your headphones from a spike in DC at the outputs. Thump or pop upon power on/off. You should consider incorporating a timer delay of some sort.

 

[paradoxper]

That's not even remotely what I meant. I meant in most circumstance, don't install a TRS connector in the amp at all. It's not a great connector for any situation that can pass a lot of current.



Song paused and volume reduced should be fine. Just don't want to risk a potential short while there is music playing.

I'll only run balanced. I was under the impression there was an active operational reason why though.

And this is due to two amps failing back to back when playing with single ended headphones while the CFA3 was on.

So I'm rather unsatisfied with the reasoning provided. Check the box for bad luck and put the blame on Murphy.

 

[migo]

You are probably trying to save your headphones from a spike in DC at the outputs. Thump or pop upon power on/off. You should consider incorporating a timer delay of some sort.

It is my habit from pass times... most valuable component should be connected/powered last and disconnected first. Transient effect currents when powering on/off can have unwanted consequences. My current amp has delayed output connection, but I'm considering to get CFA3 instead, but it must be safe I've 5y old boy here.

 

[paradoxper]

How much does it cost to commission a build for the CFA3? Thanks.

For you anything. It will depend on a number of factors but $2.2-3.2k is a good start.

 

[rsbrsvp]

Has anyone heard the tube hybrid yet? I'm getting a bit restless wanting to hear some feedback.