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Speaker amps for headphones - Page 131

post #1951 of 3116

Umm, it was this thread, about 100 pages ago. 

 

I'm disappointed that all of you have not memorized every page of this thread.  I mean, I've even memorized all of the formulas. 

 

Okay, that isn't even close to true.  In fact, I'm at my age I have enough problems remembering what day of the week it is.  But I do appreciate all of the hard work that has gone into all of the spreadsheet building...

post #1952 of 3116
Quote:
Originally Posted by Gary in MD View Post
 

Umm, it was this thread, about 100 pages ago. 

 

I'm disappointed that all of you have not memorized every page of this thread.  I mean, I've even memorized all of the formulas. 

 

Okay, that isn't even close to true.  In fact, I'm at my age I have enough problems remembering what day of the week it is.  But I do appreciate all of the hard work that has gone into all of the spreadsheet building...

Oh gosh...I had totally forgot the first page of this thread, it has been a while since i last looked LMAO. :o

post #1953 of 3116

Just joined the club with a TBI Millenia driving my LCD3, great sound overall but I am using a soundcard as a dac for the moment which does not due the amp justice. Had to build a temporary resistor box until I get all the parts for the permanent one and it does the job well. Used what I had lying around for it(one 2.2ohm 3W and two 3.3 5W in series for each channel)

Now I just have to search for the perfect DAC to go with it...end game setup here I come.

 

A huge thanks to Gary for recommending this great little amp. 

post #1954 of 3116

@potterma and others curious about my LDR-based preamp. I have installed the "HiZ upgrade" chip and going back and forth between old and new is quite astonishing. The entire signal seems much more "effortless" sounding now! Especially at higher volumes, everything just seems so 3D for lack of a better term. All the little details around each note are much more noticeable than before, and it really shows in the highs, along with a better texture in the bass. I don't know exactly what makes a LDR preamp so great compared to other options I have tried, as there are better specs of different solutions, but i think it has to do with the isolation of power, elimination of wiper contacts, and extremely tight calibration thanks to the software controller board.

 

EDIT: This makes me really wish i had an oscilloscope to verify just how "untouched" the signal is before/after the preamp. That's my hunch atleast.


Edited by brunk - 12/17/13 at 2:54pm
post #1955 of 3116
Quote:
Originally Posted by m17xr2b View Post
 

Just joined the club with a TBI Millenia driving my LCD3, great sound overall but I am using a soundcard as a dac for the moment which does not due the amp justice. Had to build a temporary resistor box until I get all the parts for the permanent one and it does the job well. Used what I had lying around for it(one 2.2ohm 3W and two 3.3 5W in series for each channel)

Now I just have to search for the perfect DAC to go with it...end game setup here I come.

 

A huge thanks to Gary for recommending this great little amp. 

[CORRECTED]With the 2.2ohm resistor in series with the two 3.3ohm the resistance is simply additive to the headphone impedance. If they're 32 ohm headphones the effective speaker load is 40.8ohms and you only get 2.0dB of attenuation.

 

If you use the "preferred resistor network" with R2=6.6 and R3=2.2 you get a speaker load of 8.7ohms and 12.5 dB of attenuation.

Headphone_Resistor_Network_Preferred.jpg 


Edited by robrob - 12/17/13 at 8:43pm
post #1956 of 3116
Quote:
Originally Posted by brunk View Post
 

@potterma and others curious about my LDR-based preamp. I have installed the "HiZ upgrade" chip and going back and forth between old and new is quite astonishing. The entire signal seems much more "effortless" sounding now! Especially at higher volumes, everything just seems so 3D for lack of a better term. All the little details around each note are much more noticeable than before, and it really shows in the highs, along with a better texture in the bass. I don't know exactly what makes a LDR preamp so great compared to other options I have tried, as there are better specs of different solutions, but i think it has to do with the isolation of power, elimination of wiper contacts, and extremely tight calibration thanks to the software controller board.

 

EDIT: This makes me really wish i had an oscilloscope to verify just how "untouched" the signal is before/after the preamp. That's my hunch atleast.

I was starting to wonder if I was going to have to give you a little nudge for an update on the LDR.  Glad to hear its working out.  Looks like they have done a nice job on the attenuation/impedance curve.  Good stuff!

 

Edit:  So how's that search for an O'scope for Christmas coming?


Edited by potterma - 12/17/13 at 6:39pm
post #1957 of 3116
Quote:
Originally Posted by potterma View Post
 

I was starting to wonder if I was going to have to give you a little nudge for an update on the LDR.  Glad to hear its working out.  Looks like they have done a nice job on the attenuation/impedance curve.  Good stuff!

Yeah I finally received it last week and did some playing around with it while I was messing with that switch box. It's very nice! Do see if you can demo one from Tortuga Audio :)

post #1958 of 3116
Quote:
Originally Posted by robrob View Post
 

With the 2.2ohm resistor in series with the 3.3ohm the resistance is simply additive to the headphone impedance. If they're 32 ohm headphones the effective speaker load is 37.5ohms and you only get 1.4dB of attenuation.

 

If you use the "preferred resistor network" with R2=3.3 and R3=2.2 you get a speaker load of 5.4ohms and 8.3 dB of attenuation.

Headphone_Resistor_Network_Preferred.jpg

Hmmm... I read it as a 2.2 in series with 2 3.3 ohm resistors for a total of 8.8 ohms in series.  That would give 40.8 ohms for a load and 2.1 dB attenuation.

post #1959 of 3116
Quote:
Originally Posted by brunk View Post
 

Yeah I finally received it last week and did some playing around with it while I was messing with that switch box. It's very nice! Do see if you can demo one from Tortuga Audio :)

I see a shoot out coming up between the Tortuga and my B1.... 

post #1960 of 3116
Quote:
Originally Posted by potterma View Post
 

I see a shoot out coming up between the Tortuga and my B1.... 

Do it! I really want to know how it fares against the mighty B1 :)

post #1961 of 3116
Quote:
Originally Posted by potterma View Post
 

Hmmm... I read it as a 2.2 in series with 2 3.3 ohm resistors for a total of 8.8 ohms in series.  That would give 40.8 ohms for a load and 2.1 dB attenuation.

 

Quote:
Originally Posted by potterma View Post
 

Hmmm... I read it as a 2.2 in series with 2 3.3 ohm resistors for a total of 8.8 ohms in series.  That would give 40.8 ohms for a load and 2.1 dB attenuation.

Yep, I missed the 2 3.3ohm resistors per channel. Your calculation is correct but if he put them in as R2=6.6 and R3=2.2 you get a speaker load of 8.7ohms and 12.5 dB of attenuation.

post #1962 of 3116
Quote:
Originally Posted by robrob View Post
 

 

Yep, I missed the 2 3.3ohm resistors per channel. Your calculation is correct but if he put them in as R2=6.6 and R3=2.2 you get a speaker load of 8.7ohms and 12.5 dB of attenuation.

Yes, exactly, if he needs that much attenuation...

 

Quote:
Originally Posted by brunk View Post
 

Do it! I really want to know how it fares against the mighty B1 :)

Might have to put it off a bit....  Wait for the insanity of year-end taper off a bit.  Work sure gets in the way of fun!

post #1963 of 3116
Quote:
Originally Posted by robrob View Post

 "preferred resistor network"

 

aka... "L pad", as it is more commonly known and used

post #1964 of 3116
That is what I really want to use . So I can vary the two resisters and listen for changes other than volume . Does someone have alink to some l pads I can try. But l pads have two coils inside usage for volume control without opening the load to speakers . Can you elaborate on the concept please.
post #1965 of 3116

I'm not sure what you mean by coils. An L-Pad is basically a series resistor then one in parallel with the load. You can potentially set up a switch to vary either or both of those resistors.

 

You could use a pot, but at speaker levels that's not really recommended. A stepped pot is better, but really that's just a switch. A transformer/autoformer is even better because now you have more efficient power transfer and no waste. (a variac if you're crazy :ph34r:)

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