Grado are designed for near 0R output impedance. The Grado RA-1 headphone amplifier has no resistors at the output.
@mikeb
using 20k Potentiometer at input solve problem.
Adding Resistor at output will make this headamps sound not good.
I will compare with other headamps 😀
using 20k Potentiometer at input solve problem.
Adding Resistor at output will make this headamps sound not good.
I will compare with other headamps 😀
00940 said:Grado are designed for near 0R output impedance. The Grado RA-1 headphone amplifier has no resistors at the output.
at spec it's say 32 Ohm Impedance
http://products.ivillage.com/search_getprod.php?masterid=2364308&
But adding 33 Ohm Resistor at output will make this amps sound not good (I don't have 32 Ohm Resistor)
00940 said:As much as I like the symasym sound, I can only suggest you to have a look on this for your grado : http://headwize.com/projects/showfile.php?file=gilmore3_prj.htm
You can simplify a bit the power supply (a lm317/337 pair is good enough). With grado, this amp just shines.
Can you suggest Replacement for 2SJ109/2SK389 i can not get it ?
I will try, If I Can Get substitution for 2SJ109/2SK389.
I Got idea from sijosae site to make sym headamps
he modified gilmore
thisSijosae easy gilmore
Sadly, there's no real replacement for those fets (which is why they're so widely used by designers). You can get some here : http://www.djgardner.com/headphone/gilmore/ (along with tons of help to build this amp).
With 8 headphone amps and going, you're gonna beat me 😉 I've had a szekeres, a ra-1 clone, a pair of pimeta and a few other 3-channels multiloop amps, a gilmore (sadly i'm gonna have to sell it along my grado sr-225), a tube amp (Audiovalve RKV) and a few other little things (opamps based). I'd like to toy this summer with the TPA6120A2. 😀
With 8 headphone amps and going, you're gonna beat me 😉 I've had a szekeres, a ra-1 clone, a pair of pimeta and a few other 3-channels multiloop amps, a gilmore (sadly i'm gonna have to sell it along my grado sr-225), a tube amp (Audiovalve RKV) and a few other little things (opamps based). I'd like to toy this summer with the TPA6120A2. 😀
MikeB, This Headamps sound very good
it beats my soha headamps (using mullard CV4003 NOS tube, Op-amps OPA 2134PA, solen caps).
This headamps give more detail, more dynamic and more wide soundstage than my Soha.
And my Soha beat other headamps that I have 😀
Thanks you, mike
How to improve THD ?
What about adding 100nF Wima paralel with 100uF ?

it beats my soha headamps (using mullard CV4003 NOS tube, Op-amps OPA 2134PA, solen caps).
This headamps give more detail, more dynamic and more wide soundstage than my Soha.
And my Soha beat other headamps that I have 😀
Thanks you, mike
How to improve THD ?
What about adding 100nF Wima paralel with 100uF ?
Ryssen said:
How much cooling do you use?
I Use Letter L heatsink 13cm x 4cm x 1 cm , it's rather hot, but not very hot, I can touch it for long time. ( I will change with this heatsink, I think is enough)
13cm x 4cm x 4cm
Attachments
dytln_02 said:MikeB, This Headamps sound very good![]()
it beats my soha headamps (using mullard CV4003 NOS tube, Op-amps OPA 2134PA, solen caps).
This headamps give more detail, more dynamic and more wide soundstage than my Soha.
And my Soha beat other headamps that I have 😀
Thanks you, mike
How to improve THD ?
What about adding 100nF Wima paralel with 100uF ?
Thanks for the compliments !
Why reduce thd ? it's below 0.01% at higher levels and 20khz, that should be low enough.
I skipped the 100nf paralell to the 100uf as it could ask for trouble, and as the outputstage runs ClassA the supplylines shouldn't be full of rubbish. But you can try if you hear a difference...
Ryssen said:
How much cooling do you use?
Was your previous question related to the headamp ? If yes, it should be enough, i thought you refered to the poweramp.
Mike
No,it was for the poweramp,just qurios how much was needed for theWas your previous question related to the headamp ?
head amp.😉
Interesting:
http://www.audiostereo.pl/forum_wpisy.html?temat=24587&p=1#k
A thread about symasym in a polnish forum... Not that i could read anything, but at least some pics of other diy-symasyms. 🙂
Mike
http://www.audiostereo.pl/forum_wpisy.html?temat=24587&p=1#k
A thread about symasym in a polnish forum... Not that i could read anything, but at least some pics of other diy-symasyms. 🙂
Mike
Mike,
Have you tried googling for Symasym? You are getting quite famous (OK, i honestly don't know what they are saying about the Symasym 🙂 ). Here are a few examples:
http://akustyka.info/articles.php?id=39
http://www.f-sport.cz/hifi/index.php?action=vthread&topic=682&forum=8&page=-1
http://www.hifi.co.yu/forum/viewtopic.php?p=24894&sid=5c9a8c53dc10e604c2b75d14e945eca0
http://www.lopuch.cz/klub.php?klub=high_end_projekty&to=4843
http://www.hifilehti.fi/keskustelu/tm.asp?m=56055&mpage=2
chip.co.id/forum/showthread.php?p=394622
Ok, PMA is involved in at least one of the czech forums, so maybe that doesn't count as surprising.
Have you tried googling for Symasym? You are getting quite famous (OK, i honestly don't know what they are saying about the Symasym 🙂 ). Here are a few examples:
http://akustyka.info/articles.php?id=39
http://www.f-sport.cz/hifi/index.php?action=vthread&topic=682&forum=8&page=-1
http://www.hifi.co.yu/forum/viewtopic.php?p=24894&sid=5c9a8c53dc10e604c2b75d14e945eca0
http://www.lopuch.cz/klub.php?klub=high_end_projekty&to=4843
http://www.hifilehti.fi/keskustelu/tm.asp?m=56055&mpage=2
chip.co.id/forum/showthread.php?p=394622
Ok, PMA is involved in at least one of the czech forums, so maybe that doesn't count as surprising.
Hi Christer, you're obviously better with googling than me !
I followed back some links from the weblogs of my symasympage, google did not show much results.
Would be nice to understand something...
Mike
I followed back some links from the weblogs of my symasympage, google did not show much results.
Would be nice to understand something...

Mike
MikeB said:
Would be nice to understand something...
Or maybe not. 🙂
Just joking. I am sure they are talking well of it.
PMA said:Well - I can understand these posts quite well ... 😉
The ones on the finnish forum too? 🙂
PMA said:I have to improve my finnish, it is same as my hungarian .. 😀
Just about as for me then. Or wait, I can actually order beer in hungarian. I don't know how to do that in finnish. 🙂
MikeB said:Would be nice to understand something...
Mike
Hi Mike,
please be sure that Polish links lead only to good information regarding symasym 🙂
The forums too😎
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