[sennsay]

Quote:

Originally Posted by netsky3 /img/forum/go_quote.gif Peete, now that my amps sounds very well I can think to the upgrades. First of all the opamp. There's differences about the output power or are similar?? If they're similar I choose a OPA627 that sounds good and it's not so expensive (about 10$ shipeed in Italy). Caps: Apart C7-8 that they capacity can't be changed (right?) I've looked again your pics and I've noticed that your caps (C3-4 11 12 13) are very different from the mines. They can improve the sound? To have a better output power an expert in electronic told me that C7-8 could be changed but cutting off the frequencies under 40HZ. I don't know if do this experiment...

Hi netsky3, yes, those caps that are different on mine (the blue ones) are 10uF Phiilips/Vishay and of very good quality, I also use them in the power supply of my Plinius IIc preamp. They are very quiet and of excellent sound quality. The two caps, C7 and C8 are the excellent Nichicon Muse FA series at 220uF, there is absolutely NO loss of bass with these caps, which have recently used to replace some already good Nichicon FGs in two of my KHA amps, they really work brilliantly in this amp too and are a fine synergistic match for the Denon cans I prefer with this amp.
The OPA627s are fine opamps here, though with the Denons, I just prefer the wonderful AD827s as you can see in the pics. With a slightly brighter set of cans, maybe the AKGs, the OPA627s might be absolutely ideal. I can tell you that the instant the music flows into the Denons on my head, I have a huge grin on my face

The Denons have never sounded so 'out-of-the-head' as they do with this amp.

 

[netsky3]

Hey sennsay, did you make other tweaks to the amp?

Mine is finished, i'll post some pics tomorrow

 

[studeb]

Got mine running. Used 1% resistors and i found some Nichicons for the output caps. I wanted to put use 0.1uF MKP caps, but the only ones i could fine were 100V Sprague 715, and they were to big.
Did anyone check the offset? i had 2.4V and reseated the PT2308, and now its at 0V.
Drives my sextets nicely, will not make my ears bleed before distortion is audible, but i would think for most people there is enough power.

 

[netsky3]

Quote:

Originally Posted by studeb /img/forum/go_quote.gif Got mine running. Used 1% resistors and i found some Nichicons for the output caps. I wanted to put use 0.1uF MKP caps, but the only ones i could fine were 100V Sprague 715, and they were to big. Did anyone check the offset? i had 2.4V and reseated the PT2308, and now its at 0V. Drives my sextets nicely, will not make my ears bleed before distortion is audible, but i would think for most people there is enough power.

Did you have listen some noticeable changes on the soundstage now?

I think that my amp needs a serious upgrade, it sound a bit confused and the sounds is blend, sometimes detailed when i hear only a guitar but with togheter other instruments the sound become dull, the soundstage is "compressed".
Sometimes the voice appears a little "screamed"

If I listen the same song from the soundcard it sounds more three-dimensional
I think to change the resistors with the 1% and other caps but i don't consider that these mods can be improve the sound

Maybe 12V and 1,5 aren't enough with my AKG, i should try with a 18V PSU.

 

[netsky3]

Here some pics of my work, i don't think that my soldering is so crappy or not?

 

[netsky3]

Today i've changed the C1-2-7-8 with four caps of 470uF hoping in a change but it sound same as before...nothing substantial differences.
This amp doesn't know what is the soundstage

I'll try a new opamp hoping in a good change otherwise i put away everything and i'll start a serious amp

 

[sennsay]

Quote:

Originally Posted by netsky3 /img/forum/go_quote.gif Today i've changed the C1-2-7-8 with four caps of 470uF hoping in a change but it sound same as before...nothing substantial differences. This amp doesn't know what is the soundstage I'll try a new opamp hoping in a good change otherwise i put away everything and i'll start a serious amp

Netsky3, there is no need to change C1 and C2 to 470uF. For starters you have changed simple and fairly good polyester caps for electrolytics - if that is indeed what you HAVE done - that could only potentially sound much worse. Fair enough to do C7 and C8, though really you are making too many changes too early, when the amp is barely even run in, the sound signature will change as the running-in process continues. IMHO, it's best to leave it alone and enjoy some tunes through it

Remove those 470uF caps (unless you meant 0.47uF, in which case leave them there), put the stock ones back, they're perfectly ok in there.
I too have made the mistake of making changes too early, it just confuses things, especially if you're new to building things like this. Relax, have fun listening to music, get the basics right and you'll have more understanding when you play around with other parts a little later. I really can understand the enthusiasm to want to play around with it! Connect a set of cans, pop some music through it, leave it for a few hours and then come back to it, select a favourite tune or three and let it wash over you and enjoy any differences - unless it sounds truly awful

And that's my smiling opinion for the morning

Cheers to you, Netsky3

 

[studeb]

Quote:

Originally Posted by netsky3 /img/forum/go_quote.gif Today i've changed the C1-2-7-8 with four caps of 470uF hoping in a change but it sound same as before...nothing substantial differences. This amp doesn't know what is the soundstage I'll try a new opamp hoping in a good change otherwise i put away everything and i'll start a serious amp

Netsky,

put back the stock C1 and C2, the 0.1uF MKT caps are fine. If you have 0.1uF MKP caps you could use those. You can leave the 470uF output caps if you want to. What kind of caps are they?
If you change the opamp, what are you going to put in? 627 is a single channel opamp, you would have to mount two on an adapter.

My amp is nowhere near what my eXStatA can be, but its a lot less $ and work to get there.

 

[netsky3]

Quote:

Originally Posted by sennsay /img/forum/go_quote.gif Netsky3, there is no need to change C1 and C2 to 470uF. For starters you have changed simple and fairly good polyester caps for electrolytics - if that is indeed what you HAVE done - that could only potentially sound much worse. Fair enough to do C7 and C8, though really you are making too many changes too early, when the amp is barely even run in, the sound signature will change as the running-in process continues. IMHO, it's best to leave it alone and enjoy some tunes through it Remove those 470uF caps (unless you meant 0.47uF, in which case leave them there), put the stock ones back, they're perfectly ok in there. I too have made the mistake of making changes too early, it just confuses things, especially if you're new to building things like this. Relax, have fun listening to music, get the basics right and you'll have more understanding when you play around with other parts a little later. I really can understand the enthusiasm to want to play around with it! Connect a set of cans, pop some music through it, leave it for a few hours and then come back to it, select a favourite tune or three and let it wash over you and enjoy any differences - unless it sounds truly awful And that's my smiling opinion for the morning Cheers to you, Netsky3

Quote:

Originally Posted by studeb /img/forum/go_quote.gif Netsky, put back the stock C1 and C2, the 0.1uF MKT caps are fine. If you have 0.1uF MKP caps you could use those. You can leave the 470uF output caps if you want to. What kind of caps are they? If you change the opamp, what are you going to put in? 627 is a single channel opamp, you would have to mount two on an adapter. My amp is nowhere near what my eXStatA can be, but its a lot less $ and work to get there.

Hi guys!
I'll put back C1-2 with the stock caps and i have bought on ebay for few dollars a OPA2134, is nothig special like the OPA627 but in any case is case better than the stock opamp (i hope)
The 470uF are of crap quality, i have bought them only for do some experiment.
In any case actually my amp doesn't have a slight soundstage with my headphones

If with the new opamp i can't drive my akg i'll sell this and start a new diy project :/

 

[calico88]

guys,
have you notice something when you use Stereo Potentiometer ?
if you do the R and L channel is not the same gain.
R channel is louder than L.

if you use Mono Mono Potentiometer/trimpot, you will not hear any difference.


Cal

 

[netsky3]

Quote:

Originally Posted by calico88 /img/forum/go_quote.gif guys, have you notice something when you use Stereo Potentiometer ? if you do the R and L channel is not the same gain. R channel is louder than L. if you use Mono Mono Potentiometer/trimpot, you will not hear any difference. Cal

In the previous pages we have talk also of the use of a pot.
It seems to "decrease" the bass but i'm no sure of this.
I'm having a lot of issues without the pot

 

[sennsay]

Quote:

Originally Posted by netsky3 /img/forum/go_quote.gif Hi guys! I'll put back C1-2 with the stock caps and i have bought on ebay for few dollars a OPA2134, is nothig special like the OPA627 but in any case is case better than the stock opamp (i hope) The 470uF are of crap quality, i have bought them only for do some experiment. In any case actually my amp doesn't have a slight soundstage with my headphones If with the new opamp i can't drive my akg i'll sell this and start a new diy project :/

Don't give up, Netsky3, it's far too early to do so, you've just made too many changes too early. The OPA2134 is a very good opamp, slightly better suited to using this kit as a preamp, though nevertheless a 2134 ran my Denons with no real problems.
I did send you a link with the dual 627s on a drop-in board, as well as the AD825 link, I think. These opamps have better drive current than the 2134, but see how you go, I stand by what I wrote in a previous post, RELAX, put the 0.1uF polyester caps back in the CI and C2 position, set a reasonable volume of the trim pots and listen to some music. The 627s ought to sound ok with the AKGs, and if not there are options. Have you tried leaving in the standard output opamp and letting it run in properly?
That is one problem with HeadFi, getting too excited and making changes too early

Make like Frankie say; "Relax, don't do it, when you want to go to it ... " S-man

 

[calico88]

Sennsay,
are you saying that this board can just use Opa627.. just drop in ?
I have mine but I thought is not working at all.
how is the sound compare to 2134 for Headphone Amplifier ?
you have not tried that as a headphone amp ?

Cal

Quote:

Originally Posted by sennsay /img/forum/go_quote.gif I did send you a link with the dual 627s on a drop-in board, as well as the AD825 link, I think. These opamps have better drive current than the 2134,

 

[calico88]

Netsky3,
don't give up... I even remake the board to this little smaller than original and it works.

Cal

 

[netsky3]

Quote:

Originally Posted by sennsay /img/forum/go_quote.gif Don't give up, Netsky3, it's far too early to do so, you've just made too many changes too early. The OPA2134 is a very good opamp, slightly better suited to using this kit as a preamp, though nevertheless a 2134 ran my Denons with no real problems. I did send you a link with the dual 627s on a drop-in board, as well as the AD825 link, I think. These opamps have better drive current than the 2134, but see how you go, I stand by what I wrote in a previous post, RELAX, put the 0.1uF polyester caps back in the CI and C2 position, set a reasonable volume of the trim pots and listen to some music. The 627s ought to sound ok with the AKGs, and if not there are options. Have you tried leaving in the standard output opamp and letting it run in properly? That is one problem with HeadFi, getting too excited and making changes too early Make like Frankie say; "Relax, don't do it, when you want to go to it ... " S-man

Yes, i know, you're right but i'm constantly scared of that amps don't have all the quantity of current for my cans
Now i put back C1-2 and i'll leave the amp play for about 2 days constantly hoping that the soundstage will be better.

I'll receive the 2134 in at least 3 weeks :/ Unfortunatly i can't buy the OPA627 of your link and the others on ebay were too expensive for me (afraid to waste money)

Quote:

Originally Posted by calico88 /img/forum/go_quote.gif Netsky3, don't give up... I even remake the board to this little smaller than original and it works. Cal

Nice work

I've measured 5V on the opamp, isn't too little for my akg?

I have the impression that with low impedances the amp works better, the sound is more "opened" and detailed with my shure scl4 (29ohm)
Thanks guys!