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Speaker amps for headphones - Page 96

post #1426 of 3116
Quote:
Originally Posted by robrob View Post
 

I was worried about hurting my speaker tube amp, a Yaqin MC-13S (push-pull 4x6CA7, 2x40w into 8 ohms), with headphones but after reading this thread I decided to give it a try. I started with a direct balanced cable connected to the speaker outputs and all three of the headsets used in this test have been modified with balanced cables. I used a raspberry pi (far right in pic) as the music source -> USB -> Aune T1 as DAC only -> Amp.

 

I listened with Modified Fostex T50RP and AKG K240 Studio cans and both sounded great. I had absolutely no issues with this setup. Max volume was around 9:30 with most music. The AKGs needed a little less volume compared to the T50RPs of course.

 

I then built an interface box so I could add a resistor network to match up the amp and headphone impedances. I started by only installing a 10 ohm 12 watt Mills wire wound non-inductive resistor across both speaker terminals (one resistor across each + and - terminal). I plan to add a 2 series + 2 parallel resistor network later. With this loading resistor setup the max volume on the knob didn't seem to change but the T50RPs sound incredible. I would have to say they sound better than when used with my Schiit Mjolnir. It's just a warm, wonderful sound. I was running late for an appointment but had trouble taking off the headphones to get out the door. The AKGs sound really good too but the sound quality seems comparable to the Mjolnir and Aune T1 headphone amps. The HE-500 did not like the tube amp with just the loading resistors. The tone was noticeably weak and hollow. Of the three headsets tried the T50RPs get the most out of this tube speaker amp.

 

I apologize for not giving a more detailed description of the sound quality but I just don't feel qualified to do so.

 

I love the Yaqin amp by the way. I replaced the Chinese preamp and phase-splitter tubes with Mullards but the original power tubes sound great. It's also quite a looker with beautiful chrome chassis to highlight the 8 tubes.

 


Shhhhh!!!! Don't tell anybody that you actually used a speaker amp to drive headphones!!!!  They'll think you're crazy!  Everybody knows that doing that is impossible!!! Your headphones will explode!!!  And they'll sound bad besides!  And your head might explode?

 

Well, welcome to the crazy club.  As you've discovered, if you can find the right match between amp and cans, you can get amazing results driving cans with speaker amps. 

post #1427 of 3116
Quote:
Originally Posted by Gary in MD View Post
 


Shhhhh!!!! Don't tell anybody that you actually used a speaker amp to drive headphones!!!!  They'll think you're crazy!  Everybody knows that doing that is impossible!!! Your headphones will explode!!!  And they'll sound bad besides!  And your head might explode?

 

Well, welcome to the crazy club.  As you've discovered, if you can find the right match between amp and cans, you can get amazing results driving cans with speaker amps. 

 

I agree G.  The key is discovered. experience is everything.

post #1428 of 3116
Quote:
Originally Posted by robrob View Post

I was worried about hurting my speaker tube amp, a Yaqin MC-13S (push-pull 4x6CA7, 2x40w into 8 ohms), with headphones but after reading this thread I decided to give it a try. I started with a direct balanced cable connected to the speaker outputs and all three of the headsets used in this test have been modified with balanced cables. I used a raspberry pi (far right in pic) as the music source -> USB -> Aune T1 as DAC only -> Amp.

I listened with Modified Fostex T50RP and AKG K240 Studio cans and both sounded great. I had absolutely no issues with this setup. Max volume was around 9:30 with most music. The AKGs needed a little less volume compared to the T50RPs of course.

I then built an interface box so I could add a resistor network to match up the amp and headphone impedances. I started by only installing a 10 ohm 12 watt Mills wire wound non-inductive resistor across both speaker terminals (one resistor across each + and - terminal). I plan to add a 2 series + 2 parallel resistor network later. With this loading resistor setup the max volume on the knob didn't seem to change but the T50RPs sound incredible. I would have to say they sound better than when used with my Schiit Mjolnir. It's just a warm, wonderful sound. I was running late for an appointment but had trouble taking off the headphones to get out the door. The AKGs sound really good too but the sound quality seems comparable to the Mjolnir and Aune T1 headphone amps. The HE-500 did not like the tube amp with just the loading resistors. The tone was noticeably weak and hollow. Of the three headsets tried the T50RPs get the most out of this tube speaker amp.

I apologize for not giving a more detailed description of the sound quality but I just don't feel qualified to do so.

I love the Yaqin amp by the way. I replaced the Chinese preamp and phase-splitter tubes with Mullards but the original power tubes sound great. It's also quite a looker with beautiful chrome chassis to highlight the 8 tubes.



You'll notice that most of these guys have added resistor networks to get more range out of the volume control and reduce hisss:
they have used the resistor network to attentuate the voltage out of their amp.
post #1429 of 3116
Quote:
Originally Posted by Chris J View Post


You'll notice that most of these guys have added resistor networks to get more range out of the volume control and reduce hisss:
they have used the resistor network to attentuate the voltage out of their amp.

Yea, the loading resistors are the first step in the trial. The volume knob currently goes to 9 to 10 o'clock for max volume and hiss isn't an issue. Has anyone come up with optimum resistor values for the HE-500?

post #1430 of 3116
Quote:
Originally Posted by brunk View Post
 

... snip ...

 

More info about the F5 - I think it perhaps has made an improvement over the hours, but I don't know if that's my brain who's doing the changing lol. There is a beyond doubt noticeable difference when it's warming up though. She sounds great though...dat fidelity! I haven't put a scope on it because I don't have one! I have been finding several uses for one over the past month though. I never thought I would say this, but I want an o-scope for Christmas! I guess that means the tweaker/geek in me has advanced to a whole new level lol.

 

OK, we need some pics of that F5!  Give me speaker amp pron!  

 

Did you do anything "off book" with the F5?  Though I haven't started to build mine yet, I'm plotting in the background...  On the signal out side, did you do just binding posts or something else?  XLR out the front, perhaps?

post #1431 of 3116
Quote:
Originally Posted by potterma View Post
 

 

OK, we need some pics of that F5!  Give me speaker amp pron!  

 

Did you do anything "off book" with the F5?  Though I haven't started to build mine yet, I'm plotting in the background...  On the signal out side, did you do just binding posts or something else?  XLR out the front, perhaps?

Hey! Yeah I'll have to take some pics later on in the week for you. For "off book" I added poly film bypass caps in the PSU, made a transformer cover out of 28ga. copper sheet metal, and added a snubber network in the PSU (not diode section though). I'm thinking of removing the limiters from the circuit to see if there's an audible improvement, along with biasing higher than normal since I have larger than needed heatsinks to work with too. I used some standard insulated binding posts with short stems so it goes through little brass as possible. I thought about the XLR idea as well, but decided against it because i didn't want to jack up the faceplate lol. Going through 10mm of aluminum in a very noticeable spot wasn't a risk i was willing to take lol. Maybe on the back side though...

post #1432 of 3116
For those crazy and/or eccentric folks (who me?) who use speaker amps that can't be stacked harmoniously on a desk-top with other cute gear, and, yes, will blow up your headphone, head, hemorrhoids, and home, this amp is a super bargain:

http://www.hafler.com/products/hafler_products_details.asp?productID=3272&viewId=1

It's big cousin, the P3000, is also very good. Both can be found used on EBay for very little money. Balanced protocol, no noise, and as much power as you need for any HP. The only Hafler products that I've been satisfied with.
post #1433 of 3116

I picked up a Stellar Labs speaker amplifier from MCM Electronics for $18 on sale (normally $35). It's a Tripath TA2024 based class T desktop amp rated at 15 watts into 4 ohms for both channels. I'm powering it with a 3 amp rated 12 volt power supply ($15 from MCM Electronics) but it can run off 8 internal AA batteries. The TA2024 chip based amp has an unbalanced (single-ended) 1/8" TRS jack for input but uses true push-pull amplification with balanced output (see schematic below--note the unbalanced, common ground input is a chip level design).

 

 

 

Max volume for me comes at 11 to 11:30 on the Stellar Labs TA2024 amp so it's not being pushed at high volume. I A/B'd it against my Schiit Mjolnir using my HE-500 cans and it stands up pretty well--no schiit, it really does. The TA2024 has a little more bass and the highs are a little less bright than the Mjolnir but both of these are really a slight improvement for the HE-500 if you ask me. Seriously, this little $18 to $35 amp punches way, way above its weight. Listen to it with an open mind (or a blind A/B test) and you'll freak out.

 

 

Note you cannot use a headphone adapter with common ground like an adapter with a female TRS socket. The speaker-to-headphone adapter must have four wires and separate L- and R- wires.


Edited by robrob - 11/24/13 at 7:57pm
post #1434 of 3116
Quote:
Originally Posted by brunk View Post
 

Hey! Yeah I'll have to take some pics later on in the week for you. For "off book" I added poly film bypass caps in the PSU, made a transformer cover out of 28ga. copper sheet metal, and added a snubber network in the PSU (not diode section though). I'm thinking of removing the limiters from the circuit to see if there's an audible improvement, along with biasing higher than normal since I have larger than needed heatsinks to work with too. I used some standard insulated binding posts with short stems so it goes through little brass as possible. I thought about the XLR idea as well, but decided against it because i didn't want to jack up the faceplate lol. Going through 10mm of aluminum in a very noticeable spot wasn't a risk i was willing to take lol. Maybe on the back side though...

 

 

Well, I think I'm done with the Carver M-200T...  

 

4 pin XLR directly off the speaker taps and lightspeed attenuator turns this into an integrated power amp!

 

Well, my face plate is only 5 mm thick, so I guess I had an easier time of it than if it were 10 mm thick.  But, the convenience of the front panel connection is hard to beat!

 

Yes, I know the XLR is up side down...  This guy will live on his side, so its actually quite a convenient location for the locking tab.

 

 

Cheers!

post #1435 of 3116
Quote:
Originally Posted by potterma View Post
 

 

 

Well, I think I'm done with the Carver M-200T...  

 

4 pin XLR directly off the speaker taps and lightspeed attenuator turns this into an integrated power amp!

 

Well, my face plate is only 5 mm thick, so I guess I had an easier time of it than if it were 10 mm thick.  But, the convenience of the front panel connection is hard to beat!

 

Yes, I know the XLR is up side down...  This guy will live on his side, so its actually quite a convenient location for the locking tab.

 

 

Cheers!

Looks very nice! Where did you get the casework done? ...and of course the two standard questions, can we see under the hood, and how does it sound? :)

 

EDIT: Nevermind on the casework, I see you just modded an original lol.


Edited by brunk - 11/24/13 at 6:40pm
post #1436 of 3116
Quote:
Originally Posted by potterma View Post Warning: Spoiler! (Click to show)

Well, I think I'm done with the Carver M-200T...  

 

4 pin XLR directly off the speaker taps and lightspeed attenuator turns this into an integrated power amp!

 

Well, my face plate is only 5 mm thick, so I guess I had an easier time of it than if it were 10 mm thick.  But, the convenience of the front panel connection is hard to beat!

 

Yes, I know the XLR is up side down...  This guy will live on his side, so its actually quite a convenient location for the locking tab.

 

 

Cheers!

 

 

Nice!  I'm always envious of DIY skill and craftsmanship.   Mr. Carver would be proud of you for this enhancement!

 

:D

 

Mike 

post #1437 of 3116
Quote:
Originally Posted by zilch0md View Post
 

 

Nice!  I'm always envious of DIY skill and craftsmanship.   Mr. Carver would be proud of you for this enhancement!

 

:D

 

Mike 

Yeah, he definitely did a great job at it. Understated elegance. I also just want to let you know I'm looking to sell my Crack+SB amp, but am waiting on someone to reply who's first in line. You're the second pal at it, so just send a PM or something if you're interested :)

post #1438 of 3116

Hey brunk,

 

I really appreciate the chance, but I'm staying clear of tubes - just for my peace of mind - as previously discussed.  But, truly, thanks very much!

 

Mike

post #1439 of 3116
Quote:
Originally Posted by zilch0md View Post
 

Hey brunk,

 

I really appreciate the chance, but I'm staying clear of tubes - just for my peace of mind - as previously discussed.  But, truly, thanks very much!

 

Mike

Ahh ok, totally forgot about that :tongue: 

post #1440 of 3116
Quote:
Originally Posted by brunk View Post
 

Looks very nice! Where did you get the casework done? ...and of course the two standard questions, can we see under the hood, and how does it sound? :)

 

EDIT: Nevermind on the casework, I see you just modded an original lol.

I just get it put together and you want me to take it back apart!  Of course, I knew that request was going to come but didn't have the camera handy when I had it open.  Next weekend I should be able to take some innards pics ...

 

As for sound... Very nice.  It truly does a very nice job across the spectrum.  And with the Lightspeed as an internal pre-amp, you get marvelous, clean signal attenuation.

 

I'm behind schedule on my A/B box, but once that is done (parts on order....) I'll do a better comparison against the F1...  Should be an interesting shoot-out!

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