There is RθJC and derating curve info in their datasheet. Evaluate how much dissipation you create in your apps vs. what they can stand by themselves and where sinking (and how much of it) could be needed or not.
Metal and metal film have less noise than metal oxide.
I would be very suspicious of any report that says otherwise.
Sort the wheat from the chaff.
So, tonight, I tried something new. I have a 216 VA EI core transformer, that measures 42 VCT unloaded. That went in as a direct replacement for a 80 VA with 2 x 18 volt secondaries. The capacitor bank prefilter is CRC using a 10 ohm resistor -- I cut two traces with an electric drill.
While the diference in sonics is very subjective, all three listeners heard the same things: MUCH more powerful bass, improved clarity throughout and far better dynamics. If I were to categorize the level of difference, it was greater than the difference between 200 ma and 600 ma hotrod levels.
A new box for the power supply transformer is needed.
I've been led to believe that sending DC along an umbilical cord is better than sending the secondary AC. Is that so?
Thanks!
While the diference in sonics is very subjective, all three listeners heard the same things: MUCH more powerful bass, improved clarity throughout and far better dynamics. If I were to categorize the level of difference, it was greater than the difference between 200 ma and 600 ma hotrod levels.
A new box for the power supply transformer is needed.
I've been led to believe that sending DC along an umbilical cord is better than sending the secondary AC. Is that so?
Thanks!
BigE: I'm not arguing, but are you hearing a lot of hum that you feel you need to get rid of? I think if you have your transformer, rectifiers, and filter caps in another enclosure, then you don't need to worry too much about additional filtering before the regulator (which has good noise rejection). I have done this with good results from a phono preamp, which was dead quiet. I had a fairly beefy raw supply with a CRC filter. The umbilical undoubtedly introduces more R and L than we suspect, so then I just used a small resistor and 4700uF capacitor on the "raw" side of the regulator.
I believe so.
I used science to convince me it had to be so.
Recently Cordell came in and confirmed that the idea of a bit of extra "R" in low cross sectional area interconnections was valid, as a way of getting slightly better performance from an rCRC supply.
Nezblue,
I have no hum now -- the transformer is bare, sitting beside the existing enclosure, wired to the screw terminals. That's not safe, so I need an external enclosure. It's just easier to leave the diode bridge in the existing enclosure and push AC at it....
AndrewT,
I have to agree with you that DC would be better to send along the umbilical. I also don't think that the vanishingly small r of the resulting rCRC will be of any significant consequence. Theoretically, yes, but practically, I don't see it.
Maybe sending AC ought to be the first try, just because it is easy. If any bad effects are noticed, then the added work of switching to DC would be warranted? Or just go to DC right away?
I have no hum now -- the transformer is bare, sitting beside the existing enclosure, wired to the screw terminals. That's not safe, so I need an external enclosure. It's just easier to leave the diode bridge in the existing enclosure and push AC at it....
AndrewT,
I have to agree with you that DC would be better to send along the umbilical. I also don't think that the vanishingly small r of the resulting rCRC will be of any significant consequence. Theoretically, yes, but practically, I don't see it.
Maybe sending AC ought to be the first try, just because it is easy. If any bad effects are noticed, then the added work of switching to DC would be warranted? Or just go to DC right away?
A few milli ohms of resistance before the filtering caps have a significant effect at the high frequencies of some of the interference that gets into our systems.
The r in the rCRC is the secondary resistance and it creates a "filter".
Without that r the capacitance is not a filter.
Hi,
I've just started building my DCB1 Hypnotize kit and have a couple of stupid questions that I would be grateful if someone could answer. I've read as much as I can of this and the other Mez monster threads but can't find the answers I need (or answers written in a language a newby can understand).
-I'm going to hot-rod. Starting with 10ohm then working my way up. I've seen various heatsinks with various values/modifications to the design but can't see anyone stating a required size or dissipation value. At the max hot rod setting what sort of size sink am I looking for; presumably bolting to the case won't cut when hot-rodded to this level? Shipping of cases is quite expensive to the UK so I just want to ensure it integrates properly. Something like this if one per FET
07WN-01500-A-200 - H S MARSTON - HEAT SINK, UNDRILLED, 1.5°C/W | Farnell UK
or am I better buying large sinks and using them as the walls to the chassis, like a class A amp?
-The build guide suggests that for a hot rod you may want consider a transformer of 2x15v 50-100VA. Most builds I have seen here have different values (even if hot rodded) for the secondarys and VA rating. How critical is it to get these values correct? The price difference between a 50VA and a 100VA transformer is negligible so if I understand VA ratings properly I should just go for 100VA just in case I want to use it for more demanding uses in the future?
-When I understand things a bit better I aspire to have a remote controlled volume and input selector. Is the Vout point on the board suitable for powering these additions if combined with an appropriate regulator?
Thanks in advance, I'm sure I'll be back with more later.
I've just started building my DCB1 Hypnotize kit and have a couple of stupid questions that I would be grateful if someone could answer. I've read as much as I can of this and the other Mez monster threads but can't find the answers I need (or answers written in a language a newby can understand).
-I'm going to hot-rod. Starting with 10ohm then working my way up. I've seen various heatsinks with various values/modifications to the design but can't see anyone stating a required size or dissipation value. At the max hot rod setting what sort of size sink am I looking for; presumably bolting to the case won't cut when hot-rodded to this level? Shipping of cases is quite expensive to the UK so I just want to ensure it integrates properly. Something like this if one per FET
07WN-01500-A-200 - H S MARSTON - HEAT SINK, UNDRILLED, 1.5°C/W | Farnell UK
or am I better buying large sinks and using them as the walls to the chassis, like a class A amp?
-The build guide suggests that for a hot rod you may want consider a transformer of 2x15v 50-100VA. Most builds I have seen here have different values (even if hot rodded) for the secondarys and VA rating. How critical is it to get these values correct? The price difference between a 50VA and a 100VA transformer is negligible so if I understand VA ratings properly I should just go for 100VA just in case I want to use it for more demanding uses in the future?
-When I understand things a bit better I aspire to have a remote controlled volume and input selector. Is the Vout point on the board suitable for powering these additions if combined with an appropriate regulator?
Thanks in advance, I'm sure I'll be back with more later.