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"The Wire" Official Boards for All Projects Available Here! BAL-BAL, SE-SE, LPUHP

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opc

opc

Member
Joined 2004
Paid Member
BuildMeSomething said:
A nice & tidy looking build, glad to see you were able to successfully trouble shoot the PSU problem :)

|-O-|

Big weekend ahead... Had the first play of the miniSHARC front-end this morning & will finish wiring in the 2nd DAC tonight... New 8" woofer speakers will be in working order tomorrow... Then full on listening with the 2-way set-up in place, with the LPUHP amp powering the FH3 speakers ... can't wait :)

Paul
Click to expand...


Great news! Looking forward to hearing about the results :)

Take your time and double check everything! I know how exciting a whole new setup is, but it's also fraught with potential mistakes and setbacks.

Best of luck!
Owen
 
B

BuildMeSomething

Member
Joined 2011
For the SE version you don't need to populate C9 to C12

...

Thanks Owen.

Spent an evening & morning sorting out three 'The Wire' PSU v1's and managed to connect the 2x6VAC transformer to the +/-15Vdc unit... The two 5V units, one unit's variable resistor was locked at 1.8K Ohm, not an easy job replacing it. Plus, had a head scratch moment when they wouldn't go lower then 6.5V... Removed the 1K Ohm resistor with a 0 Ohm jumper & all OK :)

Then spent two days trouble shooting the miniSharc set-up, was getting input and output from the Sharc but nothing from the DAC, then realised I'd written down the LRCK & BCLK pin numbers the wrong-way round.

All the big bits just about done, now getting ready for the fine detailing :)
 
R

rondr

Member
Joined 2011
Just finished a build on a BAL-BAL board for use as a preamp. Attached at the input is a 10k attenuator. Everything sounds great but the attenuator position, in order to achieve normal listening level, is one click away from full output. I've searched the original thread and can only find a reference to BAL-SE and SE-SE as far as gain changing. In order to have a little more room on the attenuator I'd like to increase the gain by 6 to 12 dB. What would be the best way to accomplish this?
 
opc

opc

Member
Joined 2004
Paid Member
Hi rondr,

The input impedance of the BAL-BAL in standard trim is 1k, so your 10k pot means you will now have an input impedance of 900 ohms. This might be loading your source and reducing output.

There are a few things you can try...

1. Swap the the input and feedback resistors on the BAL-BAL with 10k or 50k resistors. This will increase the input impedance and prevent loading. It will also allow your pot to perform correctly.

2. Do the above, but also increase the gain by changing the ratio of the feedback resistors to the input resistors. To get 6dB (2x) gain for example, use feedback resistors that are twice the value of the input resistors.

eg. Rf = 20k and Ri = 10k will give 2x or 6dB of gain. Input impedance will increase to 10k, and with your pot, will result in a final input impedance of roughly 5k.

Cheers,
Owen
 
B

BuildMeSomething

Member
Joined 2011
Was going to give a recommendation to make a jumper between pin 8 and the pcb track, but no need... LME49990 pin 8 is not connected to anything, so should be ok leaving it.

|-O-|

Saturday wasn't so great, stripped the clock & data wiring from one DAC and spent nearly 4hrs trying to clean off the old solder from the GND holes. No thermal relief made it hard going... Saturday evening, both DACs wired correctly but only got sound from the right channel. Switched off the miniSharc set-up & the lme49990 in the left channel of my amp blew, dumping 18Vdc straight into the MA Alpair 7.3 :(

Lucky the Alpairs have a physical limiter fitted and it's still working fine... Swapped the op-amp and the amp is running again, and cooler than it has done since day one...

Today... enjoyed 2hrs of music played through the miniSharc set-up this morning, both DACs working properly. Still working on the woofer enclosures, and can start looking for an enclosure for the miniSharc :)

Paul
 
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N

northernsky

Member
Joined 2008
It works!

And it sounds good!

Thank you

northernsky

P.S. Waiting for my friend: The Wire DAC
 

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muskyhuntr

Member
Joined 2012
Hi All,

Finally got a chance to continue work on my "Wire". Completed 2 power supplies:

PS Top.jpg PS Bottom.jpg

Supply on left measures -15.04 and +14.98. Ripple as best as I can measure it is .4mV. One on right measures -15.39 +15.14. Ripple a not so good 2.1 and 2.2mV respectively. I lucked out with the transformer, I am going to use a wall wart that I constructed for my CK2II. Perfect match.

Started to put the SE to SE amp together.

The Wire.jpg

I stopped at the point shown because I had a question regarding the volume control. Seems that I read somewhere in the original Wire thread that there was a recommendation that 2 of the resistors should be jumped instead of being installed. I don't recall which ones. Sooooo, my question is what would be the best way to populate the input section of this amp. My primary phones are Senn 600HD's (300 ohm) and Beyer DT 880's (600 ohm). I have a Goldpoint 50K pot that I would like to use.

Thanks'
Jim
 

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R

rondr

Member
Joined 2011
opc said:
Hi rondr,

The input impedance of the BAL-BAL in standard trim is 1k, so your 10k pot means you will now have an input impedance of 900 ohms. This might be loading your source and reducing output.

There are a few things you can try...

1. Swap the the input and feedback resistors on the BAL-BAL with 10k or 50k resistors. This will increase the input impedance and prevent loading. It will also allow your pot to perform correctly.

2. Do the above, but also increase the gain by changing the ratio of the feedback resistors to the input resistors. To get 6dB (2x) gain for example, use feedback resistors that are twice the value of the input resistors.

eg. Rf = 20k and Ri = 10k will give 2x or 6dB of gain. Input impedance will increase to 10k, and with your pot, will result in a final input impedance of roughly 5k.

Cheers,
Owen
Click to expand...

Thanks Owen,

Your suggestion worked out well. I decided on a gain of 2. Normal listening level now is around the 12 o'clock position on the pot.

For preamp use I'd like to run parallel outputs. One feeding the main power amp and the other going to a pair of powered sub woofers. Both main and sub being located roughly 20 feet away from the output of "the wire" BAL-BAL. That would be 40 feet of cable in the signal path per channel. Is this something "the wire" is capable doing?
 
opc

opc

Member
Joined 2004
Paid Member
rondr said:
Thanks Owen,

Your suggestion worked out well. I decided on a gain of 2. Normal listening level now is around the 12 o'clock position on the pot.

For preamp use I'd like to run parallel outputs. One feeding the main power amp and the other going to a pair of powered sub woofers. Both main and sub being located roughly 20 feet away from the output of "the wire" BAL-BAL. That would be 40 feet of cable in the signal path per channel. Is this something "the wire" is capable doing?
Click to expand...

Absolutely! You shouldn't have any troubles driving long cables. Just make sure they are well made cables, and properly shielded at that length! Ideally, you should be running balanced interconnects if they are that long, but if you don't have noise issues as it is now, then everything should be fine with The Wire as a preamp.

Cheers,
Owen
 
M

muskyhuntr

Member
Joined 2012
Hi All;

Concerning my question a few posts back on wiring in a pot for the 'Wire', I was able to find this in the old thread:

1. Short R13 and R17 (I would use 0 ohm resistors)
2. Use 1M for R14 and R18

Do these values still hold true for the SE-SE V2 boards and in the same locations. I would like to use a 50K pot as I have several on hand.

Thanks
Jim
 
opc

opc

Member
Joined 2004
Paid Member
muskyhuntr said:
Hi All;

Concerning my question a few posts back on wiring in a pot for the 'Wire', I was able to find this in the old thread:

1. Short R13 and R17 (I would use 0 ohm resistors)
2. Use 1M for R14 and R18

Do these values still hold true for the SE-SE V2 boards and in the same locations. I would like to use a 50K pot as I have several on hand.

Thanks
Jim
Click to expand...

Hi Jim,

The above is correct, and will work just fine.

If you look at the schematics, you'll see that R13 and R14 (along with R17 and R18) form a resistor divider on the input of each channel of the amp. This is essentially a fixed value potentiometer, and if you need a variable value pot, then you would simply replace that fixed resistor divider with a variable one, like a pot.

Cheers,
Owen
 
opc

opc

Member
Joined 2004
Paid Member
rondr said:
Is it normal for "the wire" BAL-BAL version, being used as a preamp, to pass signal without power being applied?
Click to expand...

Yes, this is completely normal. When the BAL-BAL is off, there is still a path from input to output via the two input resistors, and the two feedback resistors. With a set of headphones on the output, you probably wouldn't notice because the headphone impedance is so low compared to the resistors, but with a power amp on the output, the impedance ratio of the amplifier input and the two feedback resistors is reasonable, and a signal will pass. I would imagine it will be relatively attenuated though...

The SE-SE does not do this because the signal goes in the positive terminal of the op-amp, and the feedback resistor ties to the negative input, meaning there is no direct path unless the SE-SE is on.

Cheers,
Owen
 
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