[gregmorris]

A bit of googling revealed the 2SK214 to be used in (or substitute in) various headphone amps or pre-amps including: BAT VK-300SE, G&W T2.6F, Szekeres, Borbely, SDS Labs.

It's not the cheapest part out there...currently priced at $2.41 at mcm. And apparently favorable for audio use.

 

[nikongod]

my 2.5c uses the same parts there.

i think im going to try to up the bias a little more now

 

[keyid]

recently I zapped my 2.5c and its sounds really good. I read somewhere that if the zap filter is too hot a resister can be added on the output, have anyone tried this? My concern is that couple tubes I loved on my soha doesnt sound that great anymore. I tried messing around with the resistor on the soha output but now considering trying on the zhaulo.

Also, have anyone tried replacing the coax input on the dac? Is a normal rca female a direct replacement?

 

[Ori]

Quote:

Originally Posted by keyid /img/forum/go_quote.gif recently I zapped my 2.5c and its sounds really good. I read somewhere that if the zap filter is too hot a resister can be added on the output, have anyone tried this? My concern is that couple tubes I loved on my soha doesnt sound that great anymore. I tried messing around with the resistor on the soha output but now considering trying on the zhaulo. Also, have anyone tried replacing the coax input on the dac? Is a normal rca female a direct replacement?

Standard RCA is fine but must be insulated from chassis.
For resistor attenuator use low values, as permitted by the output board. That's the best compromise for retaining dynamics. If it's a feedback circuit then there might be a less "offensive" way to achieve a lower gain. Contact the designer for that option.

 

[nikongod]

zhaolu 2.5c with zapfilter AND headphone board.

the inner-bits

taken mid-build. XLR's and phase switches not installed yet.
RCA's are cardas
the pot is an alps-blue
all internal signal-path wire is jupiter 28ga copper in cotton.

all boxed up.
XLR outputs AND phase switches all hooked up

my balanced mahogany cmoy clone is sitting on top.
small vent holes drilled above and below the PSU board for the zapfilter.

I am running it (direct from headphone out) through my newly obtained denon d5000 and am VERY impressed with the sound. the stock amp is really holding its own after the zapfilter upgrade. i have run it through other amps (a singlepower supra, and my millett) and am absolutely astounded with the sound quality that this bit of gear is giving. the texture of music is ALL there. the sound of the hand hitting a bongo comes out well defined. bells and the "wood block" have a tone that is to die for. a sweeet bit of gear, to be sure.

 

[minivan]

does any1 know where to get replacement for the 2 regulators on the top left of this picture? they are c5171 and a1930. what brand are they? what are the spec for their output? any other regulators i can used to substitute them?
thanks

 

[Pars]

Those aren't regulators; they are Toshiba transistors (2SA1930 and 2SC5171). What makes you think they are bad?

 

[BobMcN]

I recently got a 2.5C and did some basic mods to it, some power supply changes, bypass the analogue stage caps, put in 2107 op amps, replaced the RCA's on both analogue out and digital in, unplugged the headphone board.

I'm finding that I like the sound more using a TOSLINK connection than the digital RCA input jack. Has anyone else tried this and can you confirm it?

I see Ori has a coil of some type on his digital input to balance the signal to a true 75ohms. Anyone know exactly what is done here ... what parts/values added & removed? Perhaps that might help even this out.

Thanks,
Bob

 

[Artemus GF]

Quote:

Originally Posted by BobMcN /img/forum/go_quote.gif [size=x-small]I recently got a 2.5C and did some basic mods to it, some power supply changes,[/size] bypass the analogue stage caps, [size=x-small]put in 2107 op amps, replaced the RCA's on both analogue out and digital in, unplugged the headphone board.[/size]

I am a little bit confused, i thought the 2.5 doesn't have these bad caps?

Is there somewhere a tutorial how to remove this caps (with pictures)?

 

[Pars]

Can someone help this user (Minivan) out? I replied to his post above regarding what he assumed were voltage regulators, but were actually transistors. He PM'd me (content below) regarding these. I don't own a Zhaolu, and haven't really paid much attention to the mods thread, nor do I have schematics.

Quote:

Originally Posted by minivan thanks par for your info,appreciated that,i actually took the broad out and short the 4 brown capacitor behind the 2 opamp on the output path,but to flip the broad over, i have to take the lid when the 2 transistor screw out off. too busy to put the lid back and just turn the power on after i short the cap, that's when the smoke came out. do u think may be it's the shorting of the 4 caps that cause the problem? Quote: Originally Posted by minivan hi pars, where can u get those transitors? i blow them up when i turn the power on without screwing them on the case lol thanks advance for your time cheers Quote: Originally Posted by Pars In the US, B&D Enterprises or Audio and Video, Computer Parts, Batteries, Cable and Wiring at MCM Electronics. Australia ??? Google is your friend. Also, download the datasheets for these and pay attention to the gain class (usually 3, typically something like "V", "BL", etc.). Make sure you get the same class for both devices, and also look at the ones in there to see what they are. I wouldn't think not having them screwed down would be enough to cause them to lose their magic smoke, so you may have other problems. I would ask around on the DIY forum also.

 

[BobMcN]

Quote:

Originally Posted by Artemus GF /img/forum/go_quote.gif I am a little bit confused, i thought the 2.5 doesn't have these bad caps? Is there somewhere a tutorial how to remove this caps (with pictures)?

It's fairly straightforward if you look inside the case. They are very prominent on the analogue board. Just pull them out and put in wire, or simply jump them on the bottom of the board. Yes, there are pictures in this thread on it, but good luck finding them in 200 pages of verbage.

Bob

 

[keyid]

nice pics Nikon, if you get a chance try this out hooking up the dac and amp with decent spc wire. I did it with my soha straight from zapfilter L/R to Soha L/R, amazing improvement. The silver highs smoothed out and increased clarity without any hashness. I was using a ok interconnect before, but this just saved me money.. I think there would be more improvement with some nice pure silver.

Im wondering if I can do this with coaxial from source. The zhaulo board already has a 75ohm resister on the coaxial input. Anyone knows if this is normal? Cause the coaxial cable is supposed to be already 75ohm.

 

[keyid]

Quote:

Originally Posted by Artemus GF /img/forum/go_quote.gif I am a little bit confused, i thought the 2.5 doesn't have these bad caps? Is there somewhere a tutorial how to remove this caps (with pictures)?

This is how i did mine awhile ago.
Attached pic
hope it helps

 

[Artemus GF]

Quote:

Originally Posted by keyid /img/forum/go_quote.gif This is how i did mine awhile ago. Attached pic hope it helps

thx, I've modded it but i dont like the result, the highs are to sharp. Im thinking of undo the mod.

 

[keyid]

yea I had this prob also, rolling in the lm456 or something number fixed it. Also try using optical or get better coax cable.