jupiterjune said:
Very interesting indeed, could someone explaine me how that is. Some how it is like saying that the transistor temperature has a impact on the sound. How is that ? I can understand that you need 1-2 hrs to warm up the amp so that currents and tensions are ok, but you mean something else. Somehow almost the hotter the best (I see some of you coming with joke...), until the melting point.
Nicola said:
I had similar experience as JJ had.
My current Babo Zen has heat sink temperature of about 23 - 28 degC above ambient on steady-state equilibrium which is depending on the ambient. The sound of the current Babo Zen is distinctively better than the old version which had lower heat sink temperatures on the same bias current condition.
I wondered myself too.
I looked into the data sheet of IRFP250N and saw that when the junction temperature goes up, the transimpedance goes down. This might explain it. I am unsure of it theoretically tho . . .
Nelson Pass said:
The transconductance of the fets is higher at temperature, and
all the design and adjustment is at temperature.
Does this mean that when you design a amp, the temperature come into the design ? Meaning to say you design the amps knowing that you expect if to reach this working temperature in order to provide best / more desirable sound ?
Fs listening impression - noise in the transformer
To get rid of the small mecanical noise of the Fs transformer, what would you advise ? I wondered if they make this noise because Europ use 50Hz (instead of US 60hz) and 240V instead of 120V ? Easier would be to encapsulate / shield them in a iron can, but does that make sense ? Or is it best to replace with an other make looking for one, maybe a bit more powerfull and silent ?
Nelson Pass said:
The differences are probably not worth worrying about. I use
Plitron because we get consistent mechanical/electrical
performance. I have not even tried an Antek.
To get rid of the small mecanical noise of the Fs transformer, what would you advise ? I wondered if they make this noise because Europ use 50Hz (instead of US 60hz) and 240V instead of 120V ? Easier would be to encapsulate / shield them in a iron can, but does that make sense ? Or is it best to replace with an other make looking for one, maybe a bit more powerfull and silent ?
Re: Fs listening impression - noise in the transformer
More or less. Usually the design takes advantage of higher
transconductance as the circuit is so simple, but in any case,
all the adjustments and tweaks are done at the presumed
operating temperture, typically an hour after warmup in a
23 deg C environment, with additional adjustment after another
hour or so, then burn in, and then slight adjustment once or
twice after that if needed.
You can always reduce the AC voltage seen by the primary,
a coil being any easy way to do that. Low noise transformers
seem to be designed by slightly different rules than ordinary
ones, and one technique is to design the primary windings as
if the AC input voltage will be higher, in other words with more
turns on the windings.
Nicola said:
More or less. Usually the design takes advantage of higher
transconductance as the circuit is so simple, but in any case,
all the adjustments and tweaks are done at the presumed
operating temperture, typically an hour after warmup in a
23 deg C environment, with additional adjustment after another
hour or so, then burn in, and then slight adjustment once or
twice after that if needed.
Nicola said:
You can always reduce the AC voltage seen by the primary,
a coil being any easy way to do that. Low noise transformers
seem to be designed by slightly different rules than ordinary
ones, and one technique is to design the primary windings as
if the AC input voltage will be higher, in other words with more
turns on the windings.
Hi Nicola
I've been following this thread but I'm still not sure if this is relevant.....but.....for my F2 I used one of the cheap clairtronics from rapid......Apart from some RF which I had to deal with, which is documented on the F2 thread, the transformer is totally silent.....
just my two penneth
Regards
Ed
I've been following this thread but I'm still not sure if this is relevant.....but.....for my F2 I used one of the cheap clairtronics from rapid......Apart from some RF which I had to deal with, which is documented on the F2 thread, the transformer is totally silent.....
just my two penneth
Regards
Ed
Re: Re: Fs listening impression - noise in the transformer
Most likely a stupid question, but how would you "reduce the AC voltage seen by the primary", by using a resitor I guess, but of how much ohms / wattage ? Will there be some effect on the amps ? I reckon the secondary will also proportionnaly be reduce; will that affect the performance of the amps ?Regards
Nelson Pass said:
You can always reduce the AC voltage seen by the primary,
a coil being any easy way to do that. Low noise transformers
seem to be designed by slightly different rules than ordinary
ones, and one technique is to design the primary windings as
if the AC input voltage will be higher, in other words with more
turns on the windings.
Most likely a stupid question, but how would you "reduce the AC voltage seen by the primary", by using a resitor I guess, but of how much ohms / wattage ? Will there be some effect on the amps ? I reckon the secondary will also proportionnaly be reduce; will that affect the performance of the amps ?Regards
Re: Re: Re: Fs listening impression - noise in the transformer
You can use a resistor, or an inductor, or a capacitor or some
combinations. Of course it will affect the secondary voltage,
and of course that will affect the performance. This is one of
those areas where it is best to experiment and see what works
for you.
Nicola said:
You can use a resistor, or an inductor, or a capacitor or some
combinations. Of course it will affect the secondary voltage,
and of course that will affect the performance. This is one of
those areas where it is best to experiment and see what works
for you.
Antek transformers...
OK, I just heard back from Mr. Pass and he mentioned that it was fine to forward his comments in regards to the Antek transformer and how it performed compared to the Plitron.
Here is the start thread for it:
http://www.diyaudio.com/forums/showthread.php?postid=1233391#post1233391
And response:
> I received the transformer, and just finished playing with it a couple
> days ago. Very nice transformer with good regulation
> (5%) and good resistance to crappy AC lines.
>
> I didn't get a chance to evaluate it for noise, but I assume that the
> performance is good in that category.
>
> In any case, I can recommend it along with the Plitrons. This
> particular unit has more VA than the ones I'm using for FW.
>
> What is the cost?
> Thanks.
>
> best, np
He also mentioned that it’s worth the $51.00 for this 20 – 0 – 20 500VA Antek.
Once again, thank you for your valuable time it was very much appreciated.
Stan
OK, I just heard back from Mr. Pass and he mentioned that it was fine to forward his comments in regards to the Antek transformer and how it performed compared to the Plitron.
Here is the start thread for it:
http://www.diyaudio.com/forums/showthread.php?postid=1233391#post1233391
And response:
> I received the transformer, and just finished playing with it a couple
> days ago. Very nice transformer with good regulation
> (5%) and good resistance to crappy AC lines.
>
> I didn't get a chance to evaluate it for noise, but I assume that the
> performance is good in that category.
>
> In any case, I can recommend it along with the Plitrons. This
> particular unit has more VA than the ones I'm using for FW.
>
> What is the cost?
> Thanks.
>
> best, np
He also mentioned that it’s worth the $51.00 for this 20 – 0 – 20 500VA Antek.
Once again, thank you for your valuable time it was very much appreciated.
Stan
Re: Re: Antek transformers...
who's Robin Masters?
I'm bloody Serb and I dunno who's that ............
ps. when someone have that mileage under own bu** ,somehow I doubt he have need for direct comparisons......
if it sings,then it sings ..........
( ya know that I have secret connection in Pass Labs )
edit:
crazy yankee
http://en.wikipedia.org/wiki/Robin_Masters
mpmarino said:
......
Hmmm, how would you know?
Are you Robin Masters? Is Oly Robin Masters? I'm getting suspicious.
who's Robin Masters?
I'm bloody Serb and I dunno who's that ............
ps. when someone have that mileage under own bu** ,somehow I doubt he have need for direct comparisons......
if it sings,then it sings ..........
( ya know that I have secret connection in Pass Labs
)edit:
crazy yankee
http://en.wikipedia.org/wiki/Robin_Masters
F2 voltage measuring
while listening if have the odd impression the F2 is doing strange thing, like tensions varies after 1 hour of running. I thought o measure tensions and looked on the firstwatt for the SRV-OManual hoping there would be in the schematic some indication of what are the normal voltage. I found the schematic but it holds no indication unlike for example the F1 or F3. Would Mr Pass or anybody know a document where i could find these indications ?
Kind regards
while listening if have the odd impression the F2 is doing strange thing, like tensions varies after 1 hour of running. I thought o measure tensions and looked on the firstwatt for the SRV-OManual hoping there would be in the schematic some indication of what are the normal voltage. I found the schematic but it holds no indication unlike for example the F1 or F3. Would Mr Pass or anybody know a document where i could find these indications ?
Kind regards
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.