193L in a Modded DAC-AH..

[JandG]

Yes, I have...useing 26DHT & 27 IDHT with batteries, but basically was just a very low gain stage & not really needed w/ my amps. I have very sensitive tube amps. If you are useing SS amps, then a dose of a 27 would be nice.....*s* Just do a simple cap coupled RC circuit for the 27. You can go down to 75v easily w/ 27 & bias with 1 AA NiMH per 27 for battery cathode bias. If you go 180v then 9v NiMH should be fine. load plate with 33k resistor & use .22uf coupling cap. use a 10k grid resistor on the 27, basically where a 100k pot would go. 27 has a gain of only 7 or 8, something close to that. You can take & series up some Dewalt power drill battery packs for B+ & have very quiet supply.Filaments on 27 is 2.5v @ 1.75a I think & can be done AC, but DC is better for quiet...
Joe

 

[kennykong]

Thanks Joe for the comments and recomendations! I really appreciate that especially Im a beginner DIY. just wondering hows the tube output compared to just simple cap bypass and choke?

And if u have time, can u pls do me a favor giving me a step-by-step instructions, to build the tube output cos i have no knowledge in tube design? Or is there anywhere i can find the step-by-step diagram showing how to put everything together? For example, components that i need; Basic connections to put everything together; and Power supply connection? Something lets say for a layman? I tried to hard to learn and build but its hard cos usually DIY fans have some basics and its frustrating when ppl are modifying and commenting bout while i cant do anything bout it!

Thanks again Joe!

Kenny.

 

[kennykong]

btw, im using a Tripath amp!

 

[JandG]

I can help you thru this mod, I have the dac out of system for a while because of large changes in system. So I can actually look for you. I would do the tube output with that amp. It will make sweet music. 27 IDHT's @ low voltage & I can send you a schematic & adjust it for you verbally thru e-mail. If you like digital sources, then you really need to have a small, almost no gain stage of this 27, not a buffer, persay, but only a gain of 7-8, something close to that. I have all info on 27 & 26 so I can give the op-points & also the ones I have ran in the real world with that very dac.
Joe

 

[kennykong]

Hi Joe, did you get the email i sent? Thanks!

KK

 

[JandG]

I do not think it made it, I just checked & not in junk maial eaither, so maybe try again & I will confirm it.
Thanks Joe

 

[kennykong]

i just sent! let me know if u got it!! thanks Joe.. Cant wait to mod the DAC!

the modded dac right now is awesome, just that its bit dark and too laid back for me when listening to some albums, but its totally fine with female vocal, harp , violin..

any ideas for further mod?

 

[JandG]

I got the e-mail, I will use the address provided to figure out what you might want to do further to the DAC. What are you useing for preamp..? or running direct..? If I were you I would put a 27 tube stage after that DAC chip & see what earlly on tube stage does for you. Closer you get up stream to source with tubes, the better off....for me at least. you might not like tubes, some people do not. I can't for the life of me can't figure out why. There is NO gain stage in that DAC now. So a low gainer good sounding 27 would be nice..*S*
Joe

 

[kennykong]

hi Joe, thanks for the prompt reply!
Actually i just hooked up a tube buffer today , a kit i bought online from Hong Kong, its an immitation of Musical Fidelity tube buffer! And i dont use any preamp at the moment. Just A pair of Klipcsh Synergy F1, DAC, tube buffer and Tripath amp.
So what you think? Btw, why dont you like tube output stage?

 

[djg440]

Can someone please confirm for the bypass cap to the rca L and R output, that the connection originates from the board at R 35 and R 36. I have seen another post showing the caps connected at points further up on the board about a inch, sorry I do not have any detailed information on the exact points , I can not locate the information on where I had seen it. So what would be correct?
Also for R53 and R36 there was a recommendation to replace the resistors with 240 ohm and set the voltage at 3.0 to 3.4 , any opinion? Thanks.