[markm1111]

Anyone compared the Roc against the Einar VC-01i? I am tossing up between these two amps to run AKG K702's single ended.

Seems far too hard to convert the K702's to balanced

 

[Zombie_X]

Quote:

Originally Posted by markm1111 /img/forum/go_quote.gif Anyone compared the Roc against the Einar VC-01i? I am tossing up between these two amps to run AKG K702's single ended. Seems far too hard to convert the K702's to balanced

I converted mine to balanced by replacing the taking them apart and then mounting a 4-pin mini xlr in mine. Hard to do and not recommended!!

 

[XLR1]

Has anyone tried the Roc with balanced Sennheiser HD800? Any feedback you can share?
Thanks

 

[johangrb]

I'm running HD800 with a Roc balanced. More detail, separation and bigger soundstage. Recommended.

 

[realmassy]

Got a new pair of he-5le today and i'm driving them with the roc/ref5. I'm surprised by how easily the roc can drive them: the volume is at about 10 o'clock and is already enough for my ears... A couple of steps more than the balanced k702

 

[FauDrei]

Congratulations.
 
How do you like HE-5LE through Roc?

 

[FauDrei]

Perhaps not many Roc (Phoenix, C-2C, C2) owners know that by changing bias voltage on your headamp you can "tailor" to certain extent it's sound: [size=x-small]raise bias voltage - brighter, snappier sound; lower bias voltage - smoother, meatier sound... I have found this particularly useful with current hungry headphones (orthos, K701...) which "blossom" with lower bias settings (or, at least, they sound better by my personal preferences).[/size]
 
[size=x-small]So, for DIY inclined Roc owners who want to experiment and know how to use multimeter:[/size]
 

 

1. Roc should be turned on and warmed up; no music playing during measurement
2. multimeter set to 20V DC
3. black probe (crocodile clip) to ground; red probe (clip) to in phase or inverted phase channel measuring point (there are left and right measuring points for in&inverted channels, but just right channel ones are represented on the picture because both left and right testing points of the same phase should show the same bias voltage)
4. Roc standard stock bias voltage is ±15V (+15V for in phase channels; -15V for inverted phase channels)
5. turning the trimpot clockwise - bias voltage increases; turning it counterclockwise - bias voltage decreases

1. bias voltage can be adjusted in 15V ± 3-4V range depending on trimpot range
2. in phase channels bias voltage should be symmetrical to inverted phase channels bias voltage (f.e. if in phase bias is set to +17V, inverted phase bias should be set to -17V)

 
My Roc preferred bias voltage is ±12V. YMMV.
 
...and, of course, you can not hold me responsible for anything that happens or does not happen to your headamp.

 

[nigeljames]

Interesting

 

[Nada]

Quote:    Originally Posted by FauDrei .....by changing bias voltage on your headamp you can "tailor" to certain extent it's sound: in phase channels bias voltage should be symmetrical to inverted phase channels bias voltage (f.e. if in phase bias is set to +17V, inverted phase bias should be set to -17V)
 
Thanks for the great post.
 
I seem to recollect that tubes give out an asymmetrical signal with the in phase peaks higher then the out of phase peaks and that this contributes to the characteristic sound signature of tubes. I wonder what would it sound like it you biased the out of phase lower the then in phase e.g. +12v @ -10V ? Cheers

 

[FauDrei]

Quote:

I seem to recollect that tubes give out an asymmetrical signal with the in phase peaks higher then the out of phase peaks and that this contributes to the characteristic sound signature of tubes. I wonder what would it sound like it you biased the out of phase lower the then in phase e.g. +12v @ -10V ? Cheers

Hmm... not sure that I understand what you are saying...
 
Are you saying that in differential (balanced) tube setup the tube that is driving inverted channel has lower peaks? This makes no sense to me because you can adjust bias of both tube (or SS, it does not matter) channels to be symmetrical.
 
Or are you saying that the characteristics of one tube channel is that positive amplitudes tend to be higher than negative ones? This makes more sense but I'm not sure it can be repicated in differential SS setup (like Roc) because in phase SS channel will still swing to its full negative amplitude while inverted one will indeed not reach the whole negative amplitude but inverted negative amplitude would really be positive amplitude in such case. Furthermore, I'm also not sure how will headphone (or speaker) drivers like such non symmetrical feed.

 

[Nada]

Quote:   by FauDrei /img/forum/go_quote.gif characteristics of one tube channel is that positive amplitudes tend to be higher than negative ones....... I'm not sure it can be replicated in differential SS
 
You are right - of course it cant be replicated in the ROC.  Sorry to waste your time with that ridiculous notion.  Make note to self...engage frontal lobes before posting......

 

[Pricklely Peete]

I wonder if the Phoenix can be tuned in this manner (the headamp section) as well ? Thanks for that tip FauDrei, cool beans

 
Not to worry or be too hard on yourself Nada, asking questions and throwing out ideas (no matter what they are) is part and parcel of learning and growing. No shame in that.
 
Peete.

 

[TigzStudio]

Awesome post man, really appreciate you putting the time in to make this picture!  What else did you try besides -12 / +12   ?  And what were the effects?  I am going to try this today and see what my Roc likes.
 
Quote:

Perhaps not many Roc (Phoenix, C-2C, C2) owners know that by changing bias voltage on your headamp you can "tailor" to certain extent it's sound: [size=x-small]raise bias voltage - brighter, snappier sound; lower bias voltage - smoother, meatier sound... I have found this particularly useful with current hungry headphones (orthos, K701...) which "blossom" with lower bias settings (or, at least, they sound better by my personal preferences).[/size]
 
[size=x-small]So, for DIY inclined Roc owners who want to experiment and know how to use multimeter:[/size]
 

 

1. Roc should be turned on and warmed up; no music playing during measurement
2. multimeter set to 20V DC
3. black probe (crocodile clip) to ground; red probe (clip) to in phase or inverted phase channel measuring point (there are left and right measuring points for in&inverted channels, but just right channel ones are represented on the picture because both left and right testing points of the same phase should show the same bias voltage)
4. Roc standard stock bias voltage is ±15V (+15V for in phase channels; -15V for inverted phase channels)
5. turning the trimpot clockwise - bias voltage increases; turning it counterclockwise - bias voltage decreases

1. bias voltage can be adjusted in 15V ± 3-4V range depending on trimpot range
2. in phase channels bias voltage should be symmetrical to inverted phase channels bias voltage (f.e. if in phase bias is set to +17V, inverted phase bias should be set to -17V)

 
My Roc preferred bias voltage is ±12V. YMMV.
 
...and, of course, you can not hold me responsible for anything that happens or does not happen to your headamp.

 

[Zombie_X]

Cool I didn't know you could tune it by adjusting the bias. I'm not to comfortable in trying this myself..

 

[FauDrei]

Quote:

I wonder if the Phoenix can be tuned in this manner (the headamp section) as well ?

I'm sure it can Peete. It is just I can not point the bias measuring points on Phoenix - because I do not know where they are. Also, watch out - Phoenix standard bias voltage should be ±18V and not ±15V.
 
I really do recommend a little experimenting: It really made nice SQ leap for me.
 
Quote:

Awesome post man, really appreciate you putting the time in to make this picture!  What else did you try besides -12 / +12   ?  And what were the effects?  I am going to try this today and see what my Roc likes.

Well, I went from ±11V to ±17V. The higher voltages made thing really tight but fleshed out. When I went lower, at first I did not notice much difference because I was listening to some old "thin" recordings. Before returning to stock ±15V, by chance, I've tried some nicely recorded Zucchero by... It was one of those What?!? moments... Full bodied yet more detailed sound (note that I was using HE-5 which REALLY eats current, experiences with dynamic headphones might not be pronounced that much).
 
From there on it was pretty straightforward deciding my voltage "sweet spot" between 12-12,5V. Before posting, I contacted KingWa to make sure there are no risks in running amp this way. The rest you know.
 
P.S.
Excuse me for late answering... I'm on the beach right now... and will be till the end of this week. For a healthy change - computers and headphones are not and will not be my priority during that period.