Jump to content
IGNORED

Analog Attenuator?


Recommended Posts

10 minutes ago, sandyk said:

 

Technical specifications such as Frequency response and Distortion etc. ?

 

 

Not specified as far as I am aware Alex.  I did see someone that did publish some FFT's elsewhere and here is a sample...

 

2Vrms input, 0dB attenuation... 

 

slagle_avc_fft_2000hz_154.thumb.jpg.3e227f7b162371131681252217544150.jpg

 

 

Frequency response -18dB...fr_slagle_avc_stock_2_153.thumb.jpg.91b3765dd95d1d0ad84706bfd5ef2b36.jpg

 

Note the scale, 1.5dB down at 10Hz.  Looks like generally less than +/- 0.1dB.  I expect the line runs straight far past 20kHz.

Link to comment
2 minutes ago, acg said:

Note the scale, 1.5dB down at 10Hz.  Looks like generally less than +/- 0.1dB.  I expect the line runs straight far past 20kHz.

 Anthony

 You could verify this if you have a Function Generator and a mV Meter.

 

 

Alex

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

Link to comment

Actually, I should have looked further into that guys measurements.  The graphs in my previous post were with a smaller lamination stack.  With the full lam stack, thus giving the full inductance in the units as shipped, the graphs are as follows:

 

-18dB input (-3dB = 2Vrms), -6dB attenuation

slagle_avc_fft_6db_136.thumb.jpg.d5fe1327d2c889fb03383048bc0c849a.jpg

 

-18dB input, -18dB attenuation:

slagle_avc_fft_18db_639.thumb.jpg.c855ad61c9c438a96b7e2943bc7286d7.jpg

 

 

Frequency response -0.3dB at 20Hz

slagle_avc_fr_full_lam_stack_175.thumb.jpg.3e81ef40cbf8df95180224a5734b1c3a.jpg

 

10kHz square, 2Vrms input, -6dB attenuation...

pa200205__sm_193.jpg.f576e1744f6247359ca5a0b9ec52aa13.jpg

 

 

 

Link to comment
16 minutes ago, acg said:

 

I have a very good audio analyser Alex, and yes I could do it, but not today (I've spent all my spare time talking on here!)

  Anthony

 I may have seen the above before you posted the 10kHz square wave response (?) , which is very good. :)

 It's a shame they aren't affordable for many people though, as they would normally need to be implemented in an existing design. 

 

Alex

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

Link to comment
1 hour ago, acg said:

I feel that I am in a position to comment on much of what has been said in this thread because I have experience with most of the stuff that people have mentioned.

 

Anthony, what a superb post. For others, Anthony may have one of the most exciting systems on the globe. Already the effort he has put in it ... wow.

But Anthony, you are right. When you have too many other sources, the input selector is a must, and with that there will be analogue sources just the same and now you need the analogue volume control.

 

I agree from one of my last escapades that the Muses chip is the better one, and maybe you recall me working on that headphone amp (which ended up as gain stage in the G3 incarnation of your DAC) and how I obtained a "consistently working" version from China somewhere. Well, after it stayed out (shipping) for 3 months, at arrival it did not work. I think it was there where I gave up the headphone amp idea, which also would have been "a best" pre-amp (input selector with VC - no gain).

Maybe I should continue a project like that. I have one cabinet for it as well - haha.

 

25901821_PhasureBASS08.jpeg.3048496bcc5cac012109f74d6a07842b.jpeg

 

Btw, I wonder ... @manisandher at some stage told he found a quite transparent pre-amp. I don't recall he shared that publically and I can't find it back in my emails. Mani, could that still be something to go for ?

Lush^3-e      Lush^2      Blaxius^2.5      Ethernet^3     HDMI^2     XLR^2

XXHighEnd (developer)

Phasure NOS1 24/768 Async USB DAC (manufacturer)

Phasure Mach III Audio PC with Linear PSU (manufacturer)

Orelino & Orelo MKII Speakers (designer/supplier)

Link to comment
1 hour ago, Superdad said:

 

Great post! :)

One of the most remarkable aspects I discovered right away when using the Slagle autoformer is the amount of detail and engagement with the music that remains ever when you turn the volume way down. The experience is completely unlike that of even the very best resistor-based attenuator.

 

Which is how it's meant to be ... a simple way of determining whether whatever you're using for doing the actual voltage division is degrading the SQ, if you have a DIY bent, is to find a good compromise setting for the volume that you use for most recordings; disconnect the part used to set the volume from the circuit, measure the resistances seen at the connections of the part, and hardwire in good quality fixed resistors to match the setting, into the circuit. Should be pretty clear in a short period of time whether there is a definite improvement ...

 

Local friend has done this for one of his Naim amps, and has left it so indefinitely - didn't make sense to spend the money, and effort to try and match the fixed setting quality.

Link to comment
7 hours ago, Superdad said:

 

Great post! :)

One of the most remarkable aspects I discovered right away when using the Slagle autoformer is the amount of detail and engagement with the music that remains ever when you turn the volume way down. The experience is completely unlike that of even the very best resistor-based attenuator.

Bingo! That is the heart of why I use a TVC. I have been using a Bent Audio transformer based volume pre amp for this reason too. I'd love to try the autoformer version, but I really like the isolation aspects of the transformers for use in my DAC I/V.

Forrest:

Win10 i9 9900KS/GTX1060 HQPlayer4>Win10 NAA

DSD>Pavel's DSC2.6>Bent Audio TAP>

Parasound JC1>"Naked" Quad ESL63/Tannoy PS350B subs<100Hz

Link to comment

I would like to retract my previous assertion that volume control in the digital domain should be avoided. I now have my Rossini hooked directly to my Pass power amp. By selecting the proper output on the Rossini (.2V, .6V, 2V, or 6V) I can stay near the top of the DACs volume range.  More comparing needs to be done but so far so good.. I believe we have a winner

 

see my system at Audiogon  https://systems.audiogon.com/systems/768

 

 

Link to comment
15 minutes ago, bbosler said:

I would like to retract my previous assertion that volume control in the digital domain should be avoided. I now have my Rossini hooked directly to my Pass power amp. By selecting the proper output on the Rossini (.2V, .6V, 2V, or 6V) I can stay near the top of the DACs volume range.  More comparing needs to be done but so far so good.. I believe we have a winner

 

 It has never really been a problem, even with earlier DACs, if there wasn't much more than 10dB of  Digital  

 attenuation used.

 The main problem is that the gain is too high in many Power Amplifiers, with quite a few being able to be driven         to full power with  a 1V  (or less) Input.

 

How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

PROFILE UPDATED 13-11-2020

Link to comment
4 hours ago, bbosler said:

I would like to retract my previous assertion that volume control in the digital domain should be avoided. I now have my Rossini hooked directly to my Pass power amp. By selecting the proper output on the Rossini (.2V, .6V, 2V, or 6V) I can stay near the top of the DACs volume range.  More comparing needs to be done but so far so good.. I believe we have a winner

 

I think it’s good that you have tested the volume control in your Rossini. I believe that it’s next to impossible to say if a, dedicated pre or direct to power amp, which is best for all people and in all audio system. What’s best with a DAC like the Rossini may not be true for another quality DAC with a digital volume control. And that’s the problem with too general asked questions or should I say believing what’s best with one DAC in one type of audio system is also the best for all DACs in all audio system. It can be worth to look up what the manufacturer of your gear and others have reached for conclusion and with which preamps, power amps and distance they have between them.

 

https://community.roonlabs.com/t/dcs-bartok-streaming-dac-hp-amp/47510/18

https://www.dcsltd.co.uk/support/can-i-omit-the-preamplifier-and-drive-the-power-amplifiers-directly-from-a-dcs-dac/

Link to comment
On 4/10/2020 at 10:12 PM, JohnSwenson said:

Hi Chris,

I spent MANY years trying to find a volume control I really liked, pots, discrete resistors, active, passive but none of them seemed to get it just right, until I tried autoformer attenuators by Dave Slagle  from Intact Audio. The ARE just the transformers, you have to add a box and connectors, but for me that is easy.

 

Using the autoformer passives is VERY different than resistor based passive controls, you don't need the super short cables etc.

 

In my main system my passive "preamp" cost about $500, the SlagleFormers, an aluminum box, some really good connectors and a switch for the two inputs. To me in my system this sounds better than anything else I have ever heard, no matter what the cost.

 

Bent Audio used to sell a passive preamp using these autoformers that have balanced ins and outs, but now it is just on the used market.

 

that Townsend one mentioned earlier looks like a promising one, but I have not heard it. It looks like it is well done. If I was in the market for buying a commercial one I might go for that one.

 

I would highly recommend looking into autoformer based volume controls, to me they beat out anything else.

 

John S.

 

I used a set of Slagle Autoformers for quite some time and they do sound good.

 

"The Truth" is another interesting preamp to look into. 

 

I find that preamps are really difficult to evaluate, as the results can be highly dependant on the association with the amplifier, the cables, power supply... 

 

I've settled on an integrated amplifier (Lavardin ISX) and have not looked back. 

 

 

Link to comment

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



×
×
  • Create New...