[nightanole]

Ive noticed alot of new style volume attenuators out there and kinda wanted to make a discussion on the pro's/con's of each. Heres my quicky list.

1. AMB δ1 The δ1 relay-based R-2R stereo attenuator
2. Gold Point stepped attenuators Prices
3. DACT DACT audio attenuators
4. The ebay ladder and series stepped attenuators
5. Lightspeed Passive Attenuator DIY "Lightspeed Attenuator" - Passive LDR Volume Control (audio optocouplers)
6. Good Old Alps RK27112A "blue velvet" http://www.alps.com/products/WebObje...K271/RK271.PDF
7. Twisted pear " Volumite" for the WM8740 (wonder if it would work on a gamma 2?) http://twistedpearaudio.com/control/volumite.aspx

Ive used the blue velvet and the ebay smt series attenuator. Not much of a fan of the feel of the ebay, but at $20 shipped it wasnt a bad experiment.

 

[ujamerstand]

volumite is a not an attenuator, it controls the joshua tree attenuator that does the actual attenuation; sorta like a lcduino that's a lot less limited in features. It also seems that the delta1 shares similar design with the joshua tree from a quick glance (the relay section at least) I wonder if I could use linuxwork's resistor calculator to calculate the values needed for joshua tree as well?

 

[nightanole]

the volumite also controls the internal digital volume control of the WM8740 dac. No external attenuator needed. Im wonder if this would sound the best since its the shortest path and the least amount of components added to the path, and its all done in the digital domain with no conversions.

 

[nikongod]

Dont forget:
Transformer/autoformer volume controls
LDR volume controls

Although they can be made with anything, the shunted analog pot is a personal favorite on a budget. link to thread with link to another thread

 

[ujamerstand]

Quote:

Originally Posted by nightanole /img/forum/go_quote.gif the volumite also controls the internal digital volume control of the WM8740 dac. No external attenuator needed. Im wonder if this would sound the best since its the shortest path and the least amount of components added to the path, and its all done in the digital domain with no conversions.

Well okay, but its still the dac that's doing the actual attenuation. I'm not sure I'd be able to hear the difference between these things though... I'm already having trouble distinguishing my gamma2's outputs... Maybe someone with experience with most of these attenuators could give us a quick breakdown?

 

[cobaltmute]

There is luvdunhill's PGA volume board and I've got one working on as well.

 

[jcx]

I certainly think digital mode soultions should be considered more often - with "24 bit" DACs delivering up to ~ 120 dB S/N at the output the "bit loss" argument is silly today

"the best" solution for 16 bit DACs would require re-dithering after digital attenuation, with a 24 bit DAC there would be no real reason to need added dither


of course it helps to have decent "gain structure" in your system - sensitive IEM really need 10-20 dB fixed attenuation to even match them to iPod output levels, much less desktop systems with ~ 10 Vrms full scale from 2 Vrms source and "low gain" of 4-5 amp [ edit added before I saw nikongod's post below]



I hacked a PIC uC into my Sony CE-775 SACD player's DAC's mode control circuit to slip in attenuation codes controlled by a linear pot read by the PIC chip 10 bit ADC

 

[nikongod]

I think digital level control is too touchy for the gain mismatches most systems have. Its not exactly a fault of digital control, but of the overall system gain.

When people are regularly using 50db of attenuation a piece of music recorded 6db from peak is riding in the 8 lowest bits when run in the digital domain. 8/(44,96) was pretty universally agreed to be inadequate for audio reproduction.

 

[error401]

I designed a PGA2320 board quite a while ago as well: MiniVol PGA2320 Volume Control - error404's Audio DIY Endeavours

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