Spirit
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Post by Spirit on Oct 5, 2008 10:22:02 GMT
Hi guys,
My x-meridian has 5V outputs. I have the vista volume control set to 0, and that's about the right volume for driving my hd600s.
Anything above about 60% on the volume, and it clips.
How difficult would it be to figure out what to modify to get it down to a more reasonable level? Ideally, where 100% doesn't clip.
I assume it would require someone with pretty extensive knowledge to figure out the circuit [hard part], and then replace said component with a more appropriate one.
High-res photos can be easily taken, or I'd be happy to send the card to someone who'd be willing.
If only a circuit diagram were available...
Cheers!
Phil
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pagan
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Post by pagan on Nov 9, 2008 11:32:04 GMT
Might be adjusting the wrong volume control
Theres one on the task bar one in the auzentech control panel and one in the windows control panel.
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robertkd
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Electronics Engineer from sunny Queensland
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Post by robertkd on Nov 9, 2008 13:46:28 GMT
Phil, I'm not surprised given the impedance of the HD600's is 300 ohms, this medium impedance is not in it self difficult to drive per say! The difficulty is generating adequate voltage swing, I am not familiar with the reference to "x-meridian has 5V outputs" Alex my be your best help but in general computer sound cards are more suited to lower impedance headphones the catch here is that the combination of a headphone amplifier such as the SC HA will improve voltage drive capability and allow the sound card to produce better, cleaner audio by not loading the output stage of the sound card  so how are your exams going,....  |
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rickcr42
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Post by rickcr42 on Nov 9, 2008 15:57:22 GMT
Medium impedance cans usually need a damn lot of voltage drive to get any kind of listenable volume level with the available 5 Volts enough BUT only if that spec is into tht load ! more likely the output stage is capable of the voltage only into a lod of 10K Ohms or better which means the actual voltag level will drop off as the load impedance is lowered creating your "clipping" situation with headphone use but not if you are driving a line level input (10-50 or as high as 100K ohms) The answer could be to hang a simple battery operated "naked" (open loop  ) buffer on the output.Where this becomes LESS simple is the dirty little secret is most monolithic buffers want to also be driven from a low impedance or THEIR performance suffers so you need to ""buffer" the buffer. Quick "N Dirty would be a unity gain op-amp stage at the input of the buffer,this has the potential to also be a full blown headphone amp since being an op-amp you can run it either in the unity gain mode (gain of 1 or unity) or by choosing the feedback resistors with gain.the downside is you are now adding two stages with a damn lot of active circuitry between the meridian and your headphones. Better though more labor intensive,more expensive to implement (both in aprts and in the powering) and harder to design properly but capable of FAR higher sound quality would be an FET input "buffer" to provide the high impedance input your meridian obviously need while at the same time providing a low output impedance as the interface to your headphones without loading down the output of the meridian. Soooooo.... 1-do a search on "Walt Jung Line Driver" and "Walt Jung Headphone Driver" or even "national semiconductor buffered headphone amp" for the opamp/buffer version 2-Use a BUF634 or LT1010 in high class-a bias mode with an FET buffer at the input 3-Go all the way to unity gain high current DISCRETE using an FET gate buffer and a single ended class-a high current output buffer-a lot of work but in the end the best option for ultimate SQ quality BTW-cheap and easy for the gate/monolithic buffer intput buffering is the First Watt B1 buffer (schematics available).Why it is "cheap and easy" is it not only has a low parts count but by operating on a single polarity power supply keeps both complexity and cost down due to the fact that most of the cost in any DIY audio project is in the power suppy and chassis space/design so going single polarity is a real plus if and when possible hope thisd helps rickmongo |
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Deleted
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Post by Deleted on Nov 9, 2008 20:22:22 GMT
spirit
I agree with Robert's reply.An SC HA as per the Jaycar thread will solve your problems. No searching for components from overseas, or either obtaining a special PCB or rolling your own on perf board with point to point wiring. By the time you factor in P and P from overseas sources, for quality FETs etc, and the delays, you could have the SC HA working ,and cost less. My SC HA is used in this fashion on my PC.
This also gets around the issue of the poor soundcard PSU ,as the analogue out is only lightly loaded.
Alex
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Spirit
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Post by Spirit on Nov 10, 2008 2:12:48 GMT
Might be adjusting the wrong volume control Theres one on the task bar one in the auzentech control panel and one in the windows control panel. All the volume controls in vista control the same thing - the one in taskbar = one in control panel, and the one in auzentech mixer controls the same. the catch here is that the combination of a headphone amplifier such as the SC HA will improve voltage drive capability and allow the sound card to produce better, cleaner audio by not loading the output stage of the sound card so how are your exams going,....  - my exams are going quite nicely, thankyou (no thanks to this place though ) Expecting two 7s (85+%), a 6 (75+) or a 5 (65+), and last exam I have a 6.1% buffer for a 7, so should be doable = wednesday this week. I have the scha all planned out  . Will cost just over $200. RickI love your posts - the audio related ones always go waaaay over my head  . I shall investigate said options after my exam. Will build the scha anyway, just because it looks like fun, but I have mates who might be in the market for one of the devices you describe spirit I agree with Robert's reply.An SC HA as per the Jaycar thread will solve your problems. No searching for components from overseas, or either obtaining a special PCB or rolling your own on perf board with point to point wiring. By the time you factor in P and P from overseas sources, for quality FETs etc, and the delays, you could have the SC HA working ,and cost less. My SC HA is used in this fashion on my PC. This also gets around the issue of the poor soundcard PSU ,as the analogue out is only lightly loaded. Alex Sounds good to me . You're running the x-fi straight to the SCHA? At what volume level? |
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Spirit
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Post by Spirit on Nov 12, 2008 8:43:01 GMT
@robert Exam update: Had last one today... Might just scrape a 7 (85+%), but expecting a 6. |
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Deleted
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Post by Deleted on Nov 12, 2008 8:50:23 GMT
Spirit
I normally use Creative's Media Source player at a typical level of 65-70%. However, my SC HA uses the original design gain of only 2 times.
Alex
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robertkd
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Post by robertkd on Nov 12, 2008 11:37:45 GMT
@robert Exam update: Had last one today... Might just scrape a 7 (85+%), but expecting a 6. obviously the exams are way to easy also good to see your going down the route of SC HA, I;m in the design stage of a NON WOODEN case, actually it'll be aluminum but i'm finding the case to be te mose expensive part of it,.... and i need 2 of them because I'm also making one for my eldest son ;D |
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Spirit
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That's where I'm gonna go when I die
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Post by Spirit on Nov 12, 2008 13:58:48 GMT
obviously the exams are way to easy They are I started studying... on thursday last week... haven't looked at the subject all semester... maybe I'm just good at picking up concepts and applying them also good to see your going down the route of SC HA, I;m in the design stage of a NON WOODEN case, actually it'll be aluminum but i'm finding the case to be te mose expensive part of it,.... and i need 2 of them because I'm also making one for my eldest son ;D I'm going to throw mine in a $15 or so case from altronics to begin with, till I sort out just how I'm going to go about making my case. Design (with help of my Dad most probably... he's good like that), followed by the actual production. Going to go brushed black anodised aluminium, jack on the rear, 2nd output to lineout, blue led and black knob on the front.... To match:  + monitor + keyboard + mousepad... I have a feeling a mate of mine will want one when I'm done... |
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) buffer on the output.Where this becomes LESS simple is the dirty little secret is most monolithic buffers want to also be driven from a low impedance or THEIR performance suffers so you need to ""buffer" the buffer.
- my exams are going quite nicely, thankyou (no thanks to this place though 
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. I shall investigate said options after my exam. Will build the scha anyway, just because it looks like fun, but I have mates who might be in the market for one of the devices you describe