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DAC1 and HD650 balanced - Page 2

post #16 of 68
Quote:
Originally Posted by dwc
So does the DEQ sound nice via the balanced outs? (i.e. anywhere near as nice as what ppl say about the dac1?)
I've never tried this in balanced operation, only in unbalanced operation. Unfortunately, the output impedance of the XLR outs on the Behringer is about 100 Ohm, even higher than that of the DAC1. I was using this for a week of two when my amp broke down and I used it as an excuse to order a Prehead MkII!
post #17 of 68
Quote:
Originally Posted by yanfeng
We are talking about the same thing and we are not talking about the same thing.
I know we can't get true balanced out with unbalanced headphone plug and IC. I am just refering to the way people make use of the balanced out of DAC1 to work with HD650. Most of them get better result than with the headphone out.
I mean, if head-fiers can do it, true balance or not, why can't Benchmark do it?
Erm... I don't think we're talking about the same thing afterall! Do you know what headfiers are doing? They're not modifying the Benchmark! They can't!

I think you need to study how balanced operation works before replying any further unless you're suggesting that Benchmark supply a special cable for balanced operation with the DAC1. Even then, this cable will only fit the HD580, 600 and 650 headphones. To run most other headphones in balanced operation you'll need to not only have another special cable but you'll need to modify your headhphones too!

So far, head-fiers have only specifically said that the DAC1 powers Sennheiser HD650 better than the Headphone outputs in balanced mode ONLY. This may not be the case with other headphones and headphones operating in unbalanced configuration from the DAC1's XLR outputs!
post #18 of 68
To answer your question:

1) Why 650 sounds good with Benchmark's XLR out is not because of XLR method is techniqually better than 'Y' cable, if used for headphone.
XLR is better than RCA is only when a) transfer distance is long and b) XLR is used to transfer signal from one 'electrical' instrument A to another electrical instrument B. A put positive to pin 1, ground to 2 and negative to 3. B receive the three signal, then 'flip' the negative, and add to positive. In this way the noise picked up by the long signal cable has been removed.
If you use XLR for simple device as headphone, headphone don't have the circuit to remove the noise. and for such as short distance it is really not needed.

2) DAC1's Headphone out contains extra circuit such as buffer and variable volum control. More circuit component harder to be clean sound. DAC1's XLR is pure sound, BUT it is only meant for voltage output. It's has no buffer and not ZERO impedience, so it can not drive most headphones. If use for headphone, the response curve will not be flat. However, due to the high impedence of HD650, and most people don't care it's ruler flat or not, you can use it with HD650.

Hope it's clear to you now.

Quote:
Originally Posted by yanfeng
I am also wondering why Benchmark simply does not make a ready headpone out in a balanced way using the modification method offered here if they are aware of such a superior connection. They could even save the cost to build an amp section, which is more than a hundred dollar. Why don't they simply do it?
post #19 of 68
Quote:
Originally Posted by yfei
(...)
XLR is better than RCA is only when a) transfer distance is long and b) XLR is used to transfer signal from one 'electrical' instrument A to another electrical instrument B. (...)
If you use XLR for simple device as headphone, headphone don't have the circuit to remove the noise. (...)
Wrong. The voice coil sees V(+) - V(-), so any common signal will cancel out.
I'd agree however that noise pickup over 2m, into headphones, will be pretty much a non-issue.
The point is getting rid of the shared signal return between the two drivers.

Quote:
(...)
2) DAC1's Headphone out contains extra circuit such as buffer and variable volum control.(...)
The line level outs will use the volume control as well (unless you switch them to the fixed setting and blow your ears out)
post #20 of 68
Quote:
Originally Posted by PeterR
Wrong. The voice coil sees V(+) - V(-), so any common signal will cancel out.
I'd agree however that noise pickup over 2m, into headphones, will be pretty much a non-issue.
The point is getting rid of the shared signal return between the two drivers.
Right, that's maybe right for Zu XLR cable, but I am not sure they wired like this or not.

Quote:
Originally Posted by PeterR
The line level outs will use the volume control as well (unless you switch them to the fixed setting and blow your ears out)
Actually we need to use the fixed settings, with no attenuation. Because if we use the volume control or with attenuation (jumpers), the output impedience will be kinda high, something like over 100 ohms. We need the output impedience as close to ZERO as possible. With fixed volume and no attenuation jumper, we got lowest impedience 30 ohms. Ok for Senn 6xx, not for low impedience japan made phones.
THEN, use foobar's software volum control to set loudness.
post #21 of 68
Thread Starter 
Thank you all for the enlightenment. I am beginning to understand the limitation of the use of the balanced out directly with headphones.
Well, I still see the possibility for Benchmar to punch a hole in DAC1, throw in some wires connecting to the balanced out ( pin 1 and pin 2, with pin 3 floating as suggested by Benchmark). Of course they have to add a dip switch: position A enables the balanced out and disable this unconventional headphone out, position B the opposite function).
Maybe they should add some words around that hole: "unconventioal headphone out, HD6XX only!"
I don't see this as terribly bad idea.
post #22 of 68
Quote:
Originally Posted by yfei
(...)Actually we need to use the fixed settings, with no attenuation. Because if we use the volume control or with attenuation (jumpers), the output impedience will be kinda high, something like over 100 ohms.(...)
The pot won't affect output impedance. The internal jumpers should be set to 0dB attenuation, that's right.
post #23 of 68
Quote:
Originally Posted by yfei
Actually we need to use the fixed settings, with no attenuation. Because if we use the volume control or with attenuation (jumpers), the output impedience will be kinda high, something like over 100 ohms. We need the output impedience as close to ZERO as possible. With fixed volume and no attenuation jumper, we got lowest impedience 30 ohms. Ok for Senn 6xx, not for low impedience japan made phones.
THEN, use foobar's software volum control to set loudness.
I'm confused about this last part.

I have set my DAC1 to 0db attenutation (the highest level). However, I have a new "problem" in that my Gilmore Reference is now too loud even at the lowest level

My understanding is that I should keep the PC volume at max, DAC1 at fixed (0db), and adjust the amp's volume pot accordingly -- in this case, sending it back to have the gain reduced. It is borderline too loud for my 650s at 2nd highest level, too loud for my SA5000 at even lowest, and obviously I have not tried it with my UE-10s

Am I incorrect in this understanding?
post #24 of 68
Actually, you should set the DAC1 output to around 2V.
post #25 of 68
Quote:
Originally Posted by some1x
Actually, you should set the DAC1 output to around 2V.


How do I do this?

Anyway I have adjusted the 10-turn pots and this has helped for now with 650s and SA5000s -- but I will end up needing to send it to reduce the gain anyway for use with my UE-10s.
post #26 of 68
If you connect DAC1 to amp, you don't need to set outpout to 0db.
DAC1's default jumper setting is the best for amp. (0db is for directly connect to HD650)

And, it's not a good idea to touch the 10-turn pots, because you don't have the measuring equipments to keep left and right to be balanced.


Quote:
Originally Posted by brianknewbie


How do I do this?

Anyway I have adjusted the 10-turn pots and this has helped for now with 650s and SA5000s -- but I will end up needing to send it to reduce the gain anyway for use with my UE-10s.
post #27 of 68
Quote:
Originally Posted by yfei
If you connect DAC1 to amp, you don't need to set outpout to 0db.
DAC1's default jumper setting is the best for amp. (0db is for directly connect to HD650)

And, it's not a good idea to touch the 10-turn pots, because you don't have the measuring equipments to keep left and right to be balanced.

I am using the XLR out from DAC1 to amp, so yes, I did need to set output to 0db because the XLR out does use this jumper setting.

10-turn pots are not exactly hard to make sure they are still in sync...I think you are overstating the complexity of this.
post #28 of 68
Quote:
Originally Posted by brianknewbie


How do I do this?
http://www4.head-fi.org/forums/showthread.php?t=120092
post #29 of 68
Hey, brianknewbie, I just noticed that you are using the DAC-1 with Empirical Audio mods. Did you try the DAC before and after the mods? I'm curious how much of an improvement you noticed.
post #30 of 68
Quote:
Originally Posted by some1x
Thanks for the link.

Can you clarify why it is desirable to set the output exactly to 2V?
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