"The Wire" Ultra-High Performance Headphone Amplifier - PCB's

[TiEx]

Originally Posted by opc

Hi TiEx,

The value of that pot depends entirely on what your source is preceding The Wire. If you're driving it with a modern piece of solid state gear, then 10k is probably the best choice. If your source is tube based, you might want something higher, and will need to figure out what the output impedance of your source is.

Generally speaking, all these pots should have the exact same log-taper, so what you said above about different resistances giving different attenuation at different levels is probably not correct. They should all be the same.

The main push to use lower resistance units is purely noise, as the lower value resistors have lower inherent noise. Using a higher value of resistance than you really need will add noise to the system for no reason.

Regards,
Owen

I am planning to use something like iBasso D7 which outputs a true line out (2vrms i presume) and very low output impedance. Can I ask you what value you are using in your "The Wire" amp? I see many design in internet use 20K pot for headphone amps. Maybe I should go for 20K to be more compatible with wide selection of sources?

Thanks for the info. And for the 2 SE-SE pcb's! Looking forward to build and use it. Will update on progress to help others!

[qusp]

he, like several of us do not use a pot at all, we use the inbuilt digital attenuator in the dac (several dacs allow this including es9018, es9012, wolfston wm8740/1 etc)

[opc]

Originally Posted by qusp

he, like several of us do not use a pot at all, we use the inbuilt digital attenuator in the dac (several dacs allow this including es9018, es9012, wolfston wm8740/1 etc)

That's exactly correct, and also recommended, but if I didn't have that option, I would use a 10k stepped attenuator and omit the input resistors on the SE-SE PCB.

All modern gear should be able to drive a 10k load without issue, even tube gear. If it cannot do that, I would step out on a limb and say it's probably not worth using.


Regards,
Owen

[qusp]

yep 10k is a good median value, but i would avoid ebay fake dacts and buy the ELMA MV series stepped unit with the thin films. in fact it appears they make the dacts for dact under license, so cheaper to go direct. is this for a portable unit? not many high quality attenuators that will fit in a small enough case for portable.

[jtktam]

hi opc

your pm box is full

-joe

[Nevod]

Sorry for the question, but will the original layouts be provided? Or at least separate images of each PCB plane? (Not that it's much different..) One could then try to make his own board.

[TiEx]

I have a good question that might be interesting to many people here.

Can BAL-SE and BAL-BAL versions of The Wire be used or adapted to work as an I/V stage for DAC like AKD12P from Acko? And if yes then can someone provide an implementation scheme on how to do this.

And the second question can this setup perform two roles and serve as I/V output stage and as a headphone amplifier?

Maybe this idea is not first around here, but I sure think it can be very useful.

I found that opa1632 is used in Anedio D1 based on es9018 and in TwistedPear The IVY III Balanced Linestage.

P.S. Very little familiar with diy but as far as I know, some preamps can serve as headphone amps. Maybe these "Wire" gems can do more than just drive the headphones. Anyhow if someone have an idea of similar kind I would like to hear it.

[qusp]

TiEX: I guess you havent been reading my posts, i'm not going to do a guide, but yes its possible, though for best performance with es9018/2 you shouldnt populate the input resistors and lower the feedback resistors to 680R. no its not the first time someone has mentioned it, ive been talking about it since the beginning of the thread and even posted pictures and a description in the build thread I started

Nevod, i'm not opc, but i'm saying no and if you have a diy process to make your own 3-4 layer pcbs i'm all ears. it is unreasonable to expect that everyone on this site give away their intellectual property for free

[Wolfsin]

Originally Posted by qusp

for best performance with es9018/2 you shouldnt populate the input resistors and lower the feedback resistors to 680R.

@qusp - Does that hold for the WM874x as well?

[qusp]

nope, this is only when using the amp as combo IV stage/headphone amp and particularly with sabre if you want to remain as much in 'current mode' output as possible. the input resistor does not exists in the sabre or for that matter acko or TP IV schema and RG would be 680R for unity gain. this way you basically end up with a buffered current mode sabre IV stage, which also drives headphones rather well