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Old 26th November 2013, 08:37 AM   #1901
IanAS is offline IanAS  England
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With my HD800 with Bal-Bal and the Auzentech's 3v, or so, single ended output, I have to turn down the PC volume controls to only a few % to get it quiet enough.

HD800 are very revealing. I could easily hear the differences made to the sound by everything between the DAC output and the Bal-Bal, and I'm talking about extra solder joints, not just the type of cable, plugs, etc. I could verify for myself other peoples findings about the difference to the sound between gold plated and silver plated XLR's ,etc.

I also found the Bal-Bal to be sensitive to power supply as when I added some Black Gate caps across the polymer caps, the BG's did their normal thing.

Other than that I've have not tried different regulators and PSU parts so far with this apart from initially feeding the Bal-Bal from the soundcard 7808 and 7908 regs. I then instead soldered on the PSU from my old CD player's DAC / analogue stage, the spec of which I'd arrived at over years of trying stuff. It's not perfect I think and I suspect the regs could be better, but currently it has discrete regs, BG's x 10,000uF, Nichicon KZ x 20,000uF, a custom toroid with 100VA around a 300VA M0 core. There are no leads, switches fuses, the Tx primaries are plugged into the 'super spur' and it's permanently on. I strongly suggest you do not do the same unless you know what you're doing.

I found the soundcard supply was causing noise, 'beeping' and 'whistling' that changed with the HDD seek! The external PSU stopped all that. There is an only just perceptible amount of that now, coming in on the single ended signal lines I guess. Maybe one day I'll get the soundcard analogue stage off there and over by the Bal-Bal, maybe the DAC chip too.

Last edited by IanAS; 26th November 2013 at 09:04 AM.
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Old 26th November 2013, 12:13 PM   #1902
opc is offline opc  Canada
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Quote:
Originally Posted by brunk View Post
Hi everyone! I will be building the BAL-BAL version soon and have a couple questions for you fine folks

1) What is the recommended toroidal for the BAL-BAL? 10VA, 20VA, 12v, 15v?
2) Alongside #1 what's a good IEC/fuse and switch?
3) My Yulong DA8 DAC bal out is 4.2v and I'll be using the internal preamp with HD-800 headphones. Will unity gain suffice, or do I need to raise it? If I do, what are the recommended resistors to switch out?

Thanks so much in advance!
Hi Brunk,

To answer your questions:

1) Any dual secondary 10VA or higher transformer will do the trick, and the secondary voltage depends on how high you want to run your rails. The BAL-BAL can accept a maximum of +/- 16V and for that you probably want 15VAC secondaries on the transformer. If you're alright with 12V rails then you can reduce that to dual 12VAC secondaries.

2) No ideas here... I use those ungodly expensive integrated units from Schurter with a switch, fuse and IEC inlet all in one, but discreet parts are probably cheaper and more DIY friendly.

3) As Ian said, 4.2V is likely going to be more than enough drive voltage. A quick calculation tells me you'll be at roughly 115dBSPL at that voltage output with unity gain on The Wire. If you really want to hit 120dBSPL then you would need a gain of 2 on the BAL-BAL, but I don't recommend that. I get away with 2VRMS on the HE-6 which gives a maximum of about 102dBSPL and I find that to be about perfect.

Cheers,
Owen
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Old 26th November 2013, 12:26 PM   #1903
AndrewT is offline AndrewT  Scotland
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Many headphones have an absolute max voltage of ~5Vac.
Your 4.2Vac output is getting close to absolute max.
A unity gain is suitable.
Check the output current capability and see if it suits driving your headphones.

With a unity gain buffer fed from a digital 4.2Vac Source you will need a lot of attenuation to help stop you going deaf.

Headphones are typically 90dB to 100dB / milliwatt.
4.2Vac into 32ohms is ~ +27dBmW (550mW)
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Old 26th November 2013, 12:38 PM   #1904
IanAS is offline IanAS  England
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A friend came over a few weeks ago with his HD650 and MDAC which we fed via USB from my 'pute.

Then swapped over to the HD800, Bal-Bal, soundcard.

He thought the latter was ridiculously good compared to the former.

And I know it can be better still.

Owen, it would be rather good if your new regulators meant all that excess PSU I'd had to use was rendered ineffective, which is what they say the super teddy regs do. I've not tried those so far due to some apathy compounded by difficulty obtaining the low noise Toshiba transistors.
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Old 26th November 2013, 02:26 PM   #1905
Mull3t is offline Mull3t  United States
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Brunk,

Like I posted on Head-Fi... the Amveco (TE62043-ND from Digikey) transformer works quite well. It may not be the cheapest option, but it's a really good quality trafo.
It's 10VA, has dual primaries, dual 15VAC secondaries. You can wire it up for center tap (if you use a power supply that requires this) or in parallel, which I think is what OPCs new supply requires.

I didn't want to answer "over there" because I thought it would be more fruitful here, but yeah like OPC says... Unity Gain is fine for your source voltage. In my experience, I have two DACs -- one that does 1.4Vrms (AMB Gamma 2) and the other at 2Vrms (Curryman ES9023). The Wire really needed a gain of 2 for the Gamma 2's 1.4Vrms output to drive most of my headphones nicely -- LCDs, Thunderpants, DT880-250. With 2VRMS Unity Gain is fine for most headphones. However, I will say that with my recently acquired AKG K240 Sextetts (voltage hungry) you really need some extra gain even with the 2VRMS of the Curryman. So I'm glad I chose a gain of 2. I have resistors for a gain of 4, but at this point I'm not going to bother.

Last edited by Mull3t; 26th November 2013 at 02:42 PM.
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Old 26th November 2013, 02:57 PM   #1906
brunk is offline brunk  United States
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Thanks everyone for the help and advice, I appreciate it.
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Old 26th November 2013, 09:29 PM   #1907
brunk is offline brunk  United States
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I've tried searching for the BAL-BAL and PSU board dimensions without any luck. What are the dimensions of these two boards? TIA.
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Old 3rd December 2013, 01:01 PM   #1908
zyker is offline zyker  Malaysia
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Quote:
Originally Posted by brunk View Post
I've tried searching for the BAL-BAL and PSU board dimensions without any luck. What are the dimensions of these two boards? TIA.
Here you go

BAL-BAL = 2.325" x 1.625"
SE-SE = 1.825" x 1.150"
BAL-SE = 2.325" x 1.625"
PSU = 2.525" x 1.150"

"The Wire" Ultra-High Performance Headphone Amplifier - PCB's
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Old 5th January 2014, 08:36 PM   #1909
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Hey all, have a question (might be something obvious I'm overlooking) in regards to my design that I'll be using with The Wire.

I realize that it is unity gain, so whatever coming in is what will be going out. However, what exactly should be the voltage that is coming out of the The Wire to my headphone jack?

Right now I have HD598s, but I am trying to design a DAC+Amp strong enough for anything I might throw at at.
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Old 6th January 2014, 12:15 AM   #1910
IanAS is offline IanAS  England
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If you look back through the last few pages OPC was talking about the HE6, and how only a low gain, if any, was enough.

Edit...In fact, just a few posts up from here, post 1902

Last edited by IanAS; 6th January 2014 at 12:20 AM.
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