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> DIY amp club V2, Post your DIY amp here (DIY)

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jazzy939
post Jan 17 2009, 12:19 AM

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There's one thread on GainClones..and T-Amps
I have not started my GC.. waiting for some parts and time... wink.gif
No more amps for me, too many already! laugh.gif

QUOTE(MadCow @ Jan 17 2009, 12:07 AM)
Icic, i guess i'll just stick to the conventional style. =)

Anyway, anybody DIYing any new amps at the moment? mind sharing?
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MadCow
post Jan 17 2009, 12:30 AM

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SOHA II seems to be a good amp to DIY, alot of good reviews about it. Cost about USD225 shipped from glassjar. Anybody got a say on this?
jazzy939
post Jan 17 2009, 12:34 AM

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USD225 is way too much for me..especially for a headphone amp!
I think someone did make a SOHA but no idea about SOHA II...
I'd rather spend the money for a good tube pre and tube phono preamp! brows.gif

This post has been edited by jazzy939: Jan 17 2009, 12:37 AM
ar188
post Jan 17 2009, 01:09 AM

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SOHA II? luckily not SOHAI? tongue.gif
jazzy939
post Jan 17 2009, 01:16 AM

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It would be if you join them together! laugh.gif

QUOTE(ar188 @ Jan 17 2009, 01:09 AM)
SOHA II? luckily not  SOHAI?  tongue.gif
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Eokboy
post Jan 18 2009, 05:56 AM

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Hai guise! Look what I got for free:

user posted image

Found it on the hallway beside an EE store with other working but unused instruments. Could only cart this benchtop DMM in my backpack. A brown person carrying around something that looks like a bomb in Amerika? Luckily can fit in the bag.

I'll go back there to see if the power supply and signal generator is still around before some bugger picks them up and sells them on ebay.
jazzy939
post Jan 18 2009, 08:24 AM

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Wow! An old school benchtop DMM! tongue.gif With a calibration sticker too! Wonder when it was last calibrated? laugh.gif
Good haul Eokboy!
Eokboy
post Jan 18 2009, 09:38 AM

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QUOTE(jazzy939 @ Jan 18 2009, 08:24 AM)
Wow! An old school benchtop DMM! tongue.gif With a calibration sticker too! Wonder when it was last calibrated? laugh.gif
Good haul Eokboy!
*
2002, last calibration due 2004 ph34r.gif

It has 4-terminal resistance measurement icon_idea.gif I found the manual in pdf too.
ccschua
post Jan 18 2009, 10:46 PM

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I just wonder how good is the shunt regulators used as power supply for opamp/DAC vs the typical LM 3x7 and 78XX series. do u find lots of improvement ?

In another way, how is the MUR 860 with black gate and 7805 compare to the shunt regulator ?

This post has been edited by ccschua: Jan 18 2009, 10:52 PM
LittleGhost
post Jan 18 2009, 11:28 PM

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^Plus and minus.

In short, shunt regulator has ugly efficiency compared to the series regulator.

In general, shunt is used widely for isolation purposes and for local regulation when the current draw is not too big while series for global regulation (providing a huge block of circuits which draws higher current).

Shunt does have some benefits over series regulator:
1) Protected against input transients (isolation feature)
2) Current output is limited by CCS, thus no explosion due to shorted outputs.
3) To a certain extent's better than the series regulator due to symmetrical current sinking and sourcing.


For your case, you'll do fine with both solutions.

Alternatively, use the super fast Jung Super Regulator to beat the crap out of both solutions.



ccschua
post Jan 18 2009, 11:46 PM

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Switching noise is inevitable especially the gears such as cdp , dac and pre and power amp are all connected to the same source.

The charging of diodes do provide some transients and feeds into the subsequent stage. So for the DAC, switching noise is totally unwanted. Therefore I still think the shunt regulators using fully discrete (no opamp at all ) gives better solution in terms of background noise, and dynamics response.

The guys at diyaudio are coming out with charge transfer regulators which (was used in airline) and to dem the input signals to the NOS tda 1541.

I will learn the crap first before I jump to what solution for the power supply for sensitive application like my TDA 1541 DAc.

This post has been edited by ccschua: Jan 19 2009, 12:02 AM
LittleGhost
post Jan 19 2009, 08:37 AM

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^switching can be prevented by forcing the regulator output to light Class A.
ar188
post Jan 19 2009, 10:42 PM

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QUOTE(jazzy939 @ Jan 17 2009, 12:19 AM)
There's one thread on GainClones..and T-Amps
just wondering why no threads on STK? thumbup.gif
ccschua
post Jan 19 2009, 11:47 PM

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QUOTE(LittleGhost @ Jan 19 2009, 08:37 AM)
^switching can be prevented by forcing the regulator output to light Class A.
*
how do you do that and with what mod ?
jazzy939
post Jan 20 2009, 05:59 AM

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Probably it is because no one is interested in it?
or no one knew about it? tongue.gif
(no advert/publicity)
No fans here lah ar188 except you know who..... wink.gif


QUOTE(ar188 @ Jan 19 2009, 10:42 PM)
just wondering why no threads on STK?  thumbup.gif
*
LittleGhost
post Jan 20 2009, 08:29 AM

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QUOTE(ccschua @ Jan 19 2009, 11:47 PM)
how do you do that and with what mod ?
*
actually, diode transients are negligible if your PSU is done right. Adding the snubber caps already eliminate most of the noises. In addition, your main circuit must have already high PSRR so it does not even matter at all. (if it doesnt have high PSRR it's not worth it anyway)


Sometimes, back EMF can cause the regulator to "momentarily" switch down. If there's enough capacitance on the output, this is usually not an issue. Performance can be further improved by forcing a constant current out of it, e.g. using an LED.


ar188
post Jan 20 2009, 02:17 PM

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QUOTE(jazzy939 @ Jan 20 2009, 05:59 AM)
Probably it is because no one is interested in it?
or no one knew about it? tongue.gif
(no advert/publicity)
No fans here lah ar188 except you know who.....  wink.gif
*
stk sounds good but is this better than CG or T-amp?
empire23
post Jan 20 2009, 03:11 PM

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Got my parts from amb and the goldpoint is coming. Haha, now just need my 4 casings, 1 for the twin trannies, 1 for the PSU and 1 for each inverse and non-inversed amp stage.


LittleGhost
post Jan 20 2009, 04:35 PM

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mlm <--- behold my finger of jealousy.



Anyway, I just pulled the trigger on three B22 boards and one s22 board.

Oh noes, sins!!!
jazzy939
post Jan 20 2009, 06:35 PM

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'better' is subjective. It is all a matter of preferences, one man's meat is another man's poison. tongue.gif
Between STKs, GCs and T-Amps each have their own strentghs and weaknesses and NOT really the same platform to be compared with.. just a different means of amplification. At the end of the day, let your ears decide! biggrin.gif

QUOTE(ar188 @ Jan 20 2009, 02:17 PM)
stk sounds good but is this better than CG or T-amp?
*

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