Author Topic: Ozmillsy's KillerDAC  (Read 39278 times)

Offline gamve

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Re: Ozmillsy's KillerDAC
« Reply #80 on: June 25, 2011, 08:17:33 PM »
Very neat Oz.
Will check out the penguin, looks like good quality at a reasonable price. Would like
to do much the same as you when I go to I2S.

Offline ozmillsy

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Re: Ozmillsy's KillerDAC
« Reply #81 on: July 14, 2014, 04:08:09 PM »
Hey Guys,   well the time has come to take a closer look at re-tuning the Dac for my current system.

My system has been sounding rolled off,  and I have been tackling that gradually.   The biggest culprit has been the Radford amp,  which was a self-imposed problem that has been fixed.     I also changed my volume control to a passive,  and this has given me a clearer window to the sound.   

The VC->AMP->SPEAKER combination is now really humming for my R2R and Vinyl rigs.  I am getting amazing extension at the top end now,   nice silky extension (not harsh).   It took a bit of IC fiddling to get it just right,  but it's almost there.   

What all this has revealed is,  the DAC (in comparison to my other front end components) has been rolled off all along,  and has been contributing to the problem !!   Like a lot of things in audio,  it's never 1 thing,  it's a combination of things. 

So I will start making updates in this thread on the things I am changing,  to attempt to tune in the DAC, and get better top end extension.     

1st change I have made is the Chokes.   I'll post pics of what has been changed shortly.
« Last Edit: July 14, 2014, 08:01:38 PM by ozmillsy »
It's all about the music,, not the equipment.

Offline ozmillsy

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Chokes
« Reply #82 on: July 16, 2014, 10:17:57 AM »
Post on the choke changes and what happened.    I previously had these chokes in the DAC,,,,,,,



I dont know what they are, but they are really heavy like an Oil filled choke.   And they have a similar kind of character.   They give a beautiful liquidity and wetness to the sound.   Like a Freed choke does,   but not to the same extreme.    When we were first dialling in the DAC,  it was to drive my SS amps in the SGR speakers,   and these chokes gave that system what it needed (SS amps can tend to be a little dry). 

But this lovely liquidity and wetness comes at an expense,   these chokes lack some top end clarity.    This has become very obvious on the current Tannoy/Radford system.     They are coming out of the DAC,  but I am keeping them because in a different component, in a different part of the system,  they could be magical.    We need different sounding parts like this to dial things in.

I've changed the above chokes with some newer UTC chokes.    There are a number of different UTC models.   The ones I am using, are (I believe) to be the preferred choice for current model Killerdacs?   Model H-72.    Here are the pics.




These H-72 chokes are very nice sounding chokes.   They have top end transparency,  and simply a nice balanced natural sound.   
« Last Edit: July 16, 2014, 10:47:20 AM by ozmillsy »
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Offline springcreek

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Re: Ozmillsy's KillerDAC
« Reply #83 on: July 16, 2014, 12:32:17 PM »
Nice one Oz, can't wait to hear it mate

Offline gamve

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Re: Chokes
« Reply #84 on: July 16, 2014, 03:27:55 PM »
Post on the choke changes and what happened.    I previously had these chokes in the DAC,,,,,,,



I dont know what they are, but they are really heavy like an Oil filled choke.   And they have a similar kind of character.   They give a beautiful liquidity and wetness to the sound.   Like a Freed choke does,   but not to the same extreme.    When we were first dialling in the DAC,  it was to drive my SS amps in the SGR speakers,   and these chokes gave that system what it needed (SS amps can tend to be a little dry). 

But this lovely liquidity and wetness comes at an expense,   these chokes lack some top end clarity.    This has become very obvious on the current Tannoy/Radford system.     They are coming out of the DAC,  but I am keeping them because in a different component, in a different part of the system,  they could be magical.    We need different sounding parts like this to dial things in.

I've changed the above chokes with some newer UTC chokes.    There are a number of different UTC models.   The ones I am using, are (I believe) to be the preferred choice for current model Killerdacs?   Model H-72.    Here are the pics.




These H-72 chokes are very nice sounding chokes.   They have top end transparency,  and simply a nice balanced natural sound.

and at 70ma the choke will be more suitably loaded to work in it's correct operating range?

Offline ozmillsy

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Re: Chokes
« Reply #85 on: July 16, 2014, 05:00:06 PM »
and at 70ma the choke will be more suitably loaded to work in it's correct operating range?
70 or 125?

What determines the # of HY's (the inductance)?   
« Last Edit: July 16, 2014, 08:19:05 PM by ozmillsy »
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Offline gamve

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Re: Ozmillsy's KillerDAC
« Reply #86 on: July 16, 2014, 09:44:10 PM »
70ma. I think 125ma is getting into low power, power amplifier territory.
You could try it both ways and see what sounds best but the choke would be loaded beter at 70ma.
« Last Edit: July 16, 2014, 09:46:28 PM by gamve »

Offline zenelectro

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Re: Chokes
« Reply #87 on: July 18, 2014, 12:49:06 AM »
70 or 125?

What determines the # of HY's (the inductance)?

The UTC's have a good current versus inductance rating, ie; at 70mA you get 13 Henrys, at 125mA you get 7 Henrys.
At 15mA or so of KD there may be even more, say 15 to 20 Henrys.

The more Henrys, the better filtering. At 20 Henrys you may be even able to use a smaller cap on the OP tube
and ditch the Jensen for a film / oil filled cap. Jensen electros are pretty coloured and fat sounding IMO. They are not always
the right solution in all cases.   

cheers

Z
 

Offline ozmillsy

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Re: Ozmillsy's KillerDAC
« Reply #88 on: July 18, 2014, 07:20:31 AM »
Zen,  great to see you back posting.  :D.  I was hoping you'd see my post and explain how the choke is working.   Thanks.

Looking at the original chokes I pulled out,  they don't appear to be dramatically different.    150ma I get 8 Hy's.   I assume as the current drops,  the Hy's increases on these chokes aswell?    We just don't have a number printed on the choke to guide us?    Is that right?

When you say smaller value cap,  what are you measuring to determine the right value?   This gets into circuit design I guess, which could get complex, but doesn't stop me asking. :)

 I vaguely remember the Jensons used in the Killer to be 100uf (I'll check this).    For example, if I dropped the cap value to 50uf,  what is the effect on the OP tubes?


« Last Edit: July 19, 2014, 11:37:40 AM by ozmillsy »
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Offline Rob181

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Re: Chokes
« Reply #89 on: July 18, 2014, 08:19:56 AM »
The UTC's have a good current versus inductance rating, ie; at 70mA you get 13 Henrys, at 125mA you get 7 Henrys.
At 15mA or so of KD there may be even more, say 15 to 20 Henrys.

The more Henrys, the better filtering. At 20 Henrys you may be even able to use a smaller cap on the OP tube
and ditch the Jensen for a film / oil filled cap. Jensen electros are pretty coloured and fat sounding IMO. They are not always
the right solution in all cases.   

cheers

Z

GREAT to see you back on the net...this post has made my day...
 
« Last Edit: July 19, 2014, 11:27:26 AM by ozmillsy »

Offline ozmillsy

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Re: OzM's KD-Resistors
« Reply #90 on: July 19, 2014, 11:36:51 AM »
Next tuning tweak,  resistors.

There are currently 70R Allen Bradleys next to the OP tubes.    Here,,,,,,,



In this particular spot,  I am advised that the resistors can be between 0-100 ,   or 40-80 (being more conservative). 

Aside from a change in volume, I'm told the lower the resistor value,  the cleaner the sound.   The higher the value,  the weightier it gets.     

Looking through my collection of 2w Shinkohs,   I have 47R and 75R values.       I'll begin with changing out the 70R-AB's with 47R-Shinkohs.     This should be quite a change.   AB's have an inherent richness to them,  changing to Shinkoh and coupled with the change in resistor value,  should be quite interesting.

Side by side.


Shinkohs installed.



« Last Edit: July 19, 2014, 04:01:38 PM by ozmillsy »
It's all about the music,, not the equipment.

Offline ozmillsy

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Re: OzM's KD-E88CC's
« Reply #91 on: July 20, 2014, 07:54:31 AM »
Obviously 1 of the easiest Killerdac mods is tube rolling.    This post will be about output tubes,  there is no shortage of options. 

The recommended choice of tube type for the KD outputs has been Phillips Miniwatt SQ E88CC tubes.   But oils aint oils, and there are any number of variants of this type of tube.

I have 4 types on hand, and they all sound different.   I'll list them here,  with comments on how they sound (baring in mind everything is system dependent).

First type is the one I have been using for the last couple of years, and what most people would have heard (for those who have previously visited me).

SQ's with writing on top


This tube is very nice,  it has body and a good amount of detail/sound staging.   It's a bit of an all rounder.
   
« Last Edit: July 20, 2014, 11:04:28 AM by ozmillsy »
It's all about the music,, not the equipment.

Offline ozmillsy

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Re: OzM's KD-E88CC's
« Reply #92 on: July 20, 2014, 08:01:02 AM »
SQ's with writing and stars


This tube is highly sought after,  but it isnt necessarily the best.    What people love about this tube,  is that it adds a sense of real flesh and weight to voices.   Most audio systems are lean and analytical, and these tubes are a quick fix for that.    But that flesh on the bone comes at a price,  you lose speed and detail.   The bottom end is quite soft,  I wont say woolly thats going too far,   but it isnt tight. 

For those people that love the J.Cash style vocal music, with real weight in delivery,  you'd love these tubes.   

This tube has an O getter (most of the SQ's do).
« Last Edit: July 20, 2014, 08:03:00 AM by ozmillsy »
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Offline ozmillsy

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Re: OzM's KD-E88CC's
« Reply #93 on: July 20, 2014, 08:08:58 AM »
SQ's with Stars, D getter



These tubes are quite scarce.  They have the stars on them, but no writing on top,  and they have a different getter (see here,,,,).


These tubes sound quite special.   They are not slow like the other stars,  they have good weight, good detail,  their strength is a harmonic beauty in delivery.  Like we get some additional decay, and this makes everything sound that much more engaging.   
« Last Edit: July 20, 2014, 08:23:54 AM by ozmillsy »
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Offline ozmillsy

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Re: OzM's KD-E88CC's
« Reply #94 on: July 20, 2014, 08:16:08 AM »
SQ's-Plain



No stars,  no writing on top,  standard O getter.     

My current favourite tube.   It has strong-really tight bass,  big sound staging and tight imaging,  clean sounding,  with a hint of decay and beauty (not the same degree of decay as the D getter, but it has just enough to stop this tube from sounding analytical).

This tube really suits my current system.   I already have an inherently warm and engaging sound with Tannoy Golds and Radford amp,  these tubes tighten up the sound,  and let through more detail.     They may not be for all systems,  but they are hitting the mark on mine.
« Last Edit: July 20, 2014, 10:43:35 AM by ozmillsy »
It's all about the music,, not the equipment.

Offline ozmillsy

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Re: OzM's KD-E88CC's
« Reply #95 on: July 20, 2014, 08:19:35 AM »
To complicate matters further,  there are date codes on the tubes,   and you know it,  the different dates sound different.

I heard a pair of early 60's SQ-Plain type tubes,  and they left me a little cold.   IIRC, the plain SQ's above are from '59.

The other tubes I have posted about are all from the 50's.   I think production quality improved in the 60's, resulting in less distortion,  but this doesnt mean they sound better.    I guess it all depends on your system.

It's handy to have different tubes in your collection.   I have used all of these tubes, at different times,  on different system configurations and in different rooms.   
« Last Edit: July 20, 2014, 08:29:18 AM by ozmillsy »
It's all about the music,, not the equipment.

Offline Jehuty

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Re: Ozmillsy's KillerDAC
« Reply #96 on: July 21, 2014, 07:39:44 PM »
Nice collection of E88CC there Oz.

You might want to speak to Bryan as I remember he uses different output valves for his KillerDAC. Not sure what valves but who knows, you might end up liking the sound  :)
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Offline ozmillsy

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Re: Ozmillsy's KillerDAC
« Reply #97 on: July 21, 2014, 09:23:55 PM »
Definitely open to trying the same tubes Bryan runs.

 Those plain '59 SQs are sounding sweet in the meantime though.   

Also have a couple more tweaks to try, in due course.
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Offline ozmillsy

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Re: OzM's KD-Plessey
« Reply #98 on: July 26, 2014, 12:33:08 PM »
Next mod,  in the search for some more top end clarity,   swap out the Dublier 8uf cap with a Plessey.

The Plessey is reported to be clean and clear with more extension,   the Dublier is fuller and weightier but has a tendency to be thick on the wrong system.



Plessey installed,,,,



(thanks for the tip Jehuty)
« Last Edit: July 26, 2014, 04:02:58 PM by ozmillsy »
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Offline Jehuty

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Re: OzM's KD-Plessey
« Reply #99 on: July 26, 2014, 04:17:33 PM »
Next mod,  in the search for some more top end clarity,   swap out the Dublier 8uf cap with a Plessey.

The Plessey is reported to be clean and clear with more extension,   the Dublier is fuller and weightier but has a tendency to be thick on the wrong system.



Plessey installed,,,,



(thanks for the tip Jehuty)

Hi Oz, do you like the Plessey better than the Dubilier?
Not all that matters can be measured, not all that can be measured matters.