Mmmokay, i dare to start a new thread – it's a first so please be patient and if anyone could help, I would be much obliged.
My question refers to the choices of preamplification for a pair of PASS ACAs that I plan to run as monoblocks.
Yes, I am aware that there is a thread with a similar topic, but in fact I don't want to go the DIY road with that one.
I use a pair of very high sensitivity DIY horn speakers, with no crossover and a single RFT driver like this one. In horn enclosures they probably have an efficiency corresponding 98db or more.
But the tweaking demon won't relent. Inspired by an article by Chris Templer at tnt-audio I intend to fit these enclosures with a pair of Goodmans Axiom 201 drivers. It looks like I'm not the only one on diyaudio thinking about this combination, there are even some success stories and a lot of interesting amplification advice as well.
Back to my horn loudspeakers are very... well... loud. For example, when driven with a 2x18 watt Audio Innovations i couldn't listen to them past "10 oclock" on the pot. Of course, with the RFT they are 8ohm but as soon as the Goodmans are going in, they become 15 ohm.
I have two music sources:
1. a DAC (the Denafrips Ares 2) with XLR outputs (this model has no volume control)
and
2. a mm preamp (obviously also without volume control).
A passive whichmagee attenuator or external volume control is what I would like to drop in this combination.
I am wondering if you could comment on my choices.
For instance:
this one that is just a volume adjuster or this slightly fancier one Do you have a suggestion which one to chose?
Other versions even have serveral values to chose from (10K/50K/100K/250K/500K).
Any suggestions?
My question refers to the choices of preamplification for a pair of PASS ACAs that I plan to run as monoblocks.
Yes, I am aware that there is a thread with a similar topic, but in fact I don't want to go the DIY road with that one.
I use a pair of very high sensitivity DIY horn speakers, with no crossover and a single RFT driver like this one. In horn enclosures they probably have an efficiency corresponding 98db or more.
But the tweaking demon won't relent. Inspired by an article by Chris Templer at tnt-audio I intend to fit these enclosures with a pair of Goodmans Axiom 201 drivers. It looks like I'm not the only one on diyaudio thinking about this combination, there are even some success stories and a lot of interesting amplification advice as well.
Back to my horn loudspeakers are very... well... loud. For example, when driven with a 2x18 watt Audio Innovations i couldn't listen to them past "10 oclock" on the pot. Of course, with the RFT they are 8ohm but as soon as the Goodmans are going in, they become 15 ohm.
I have two music sources:
1. a DAC (the Denafrips Ares 2) with XLR outputs (this model has no volume control)
and
2. a mm preamp (obviously also without volume control).
A passive whichmagee attenuator or external volume control is what I would like to drop in this combination.
I am wondering if you could comment on my choices.
For instance:
this one that is just a volume adjuster or this slightly fancier one Do you have a suggestion which one to chose?
Other versions even have serveral values to chose from (10K/50K/100K/250K/500K).
Any suggestions?
PS:
Perhaps XLR is overkill. But my DAC has balanced outputs and the Pass ACA monos that you have built also have balanced inputs.
It seems a pity to run them on RCA connections...
Unless that is, there is some nice harmonic stuff happening if run on RCAs and bridged. But no way to find without trying.
User Allan4411 has been kind enough to publish a chart here:
Amp Camp Amp - ACA
It does refer to the older 1.6 version but is probably valid.
Anyway, this question is snowballing so I'll stop complicating it now.
Thank you for your patience reading all this rambling
Perhaps XLR is overkill. But my DAC has balanced outputs and the Pass ACA monos that you have built also have balanced inputs.
It seems a pity to run them on RCA connections...
Unless that is, there is some nice harmonic stuff happening if run on RCAs and bridged. But no way to find without trying.
User Allan4411 has been kind enough to publish a chart here:
Amp Camp Amp - ACA
It does refer to the older 1.6 version but is probably valid.
Anyway, this question is snowballing so I'll stop complicating it now.
Thank you for your patience reading all this rambling
Thank you for your answer Zen Mod!
So, if I understand this correctly, since there is no actual gain after my dac I should choose a device that only contains an attenuator, no transformer hankeypankey - a technical term like "cojones".
If the above is correct, this leaves me either with lower quality implementation like this one:
Or with a better pot, like the one depicted here:
As well as below
...which, by the way, baffles me a little bit, as it also comes with a grounded option, but am not quite sure why (will the components not be connected to a common ground anyway through the ground of the XLR cable?):
Given the sonic results of a Pass ACA, is the extra expense for the better pot justified? and if yes, which version, "common rail"
So, if I understand this correctly, since there is no actual gain after my dac I should choose a device that only contains an attenuator, no transformer hankeypankey - a technical term like "cojones"
.If the above is correct, this leaves me either with lower quality implementation like this one:
Or with a better pot, like the one depicted here:
As well as below
...which, by the way, baffles me a little bit, as it also comes with a grounded option, but am not quite sure why (will the components not be connected to a common ground anyway through the ground of the XLR cable?):
Given the sonic results of a Pass ACA, is the extra expense for the better pot justified? and if yes, which version, "common rail"
Attachments
well, if you know any of my musings, you'll find that for me autoformer volume is superior to any sort of resistive attenuator
but - to clarify my previous post - that's the case only if AVC is equipped with proper preceding buffer, which gives Cojones to drive it
in case you don't have (buffer), you're pretty much on your own, meaning that majority of sources are not up to task to blend properly with AVC
so, that's not cheap, and if you want to save some greenies, going to decent resistive attenuator is a way
take full package - that grounded thingie ( even if I can't fathom how they can sell attenuator without GND routed properly)
that small one is a toy, probably functional, but still a toy
but - to clarify my previous post - that's the case only if AVC is equipped with proper preceding buffer, which gives Cojones to drive it
in case you don't have (buffer), you're pretty much on your own, meaning that majority of sources are not up to task to blend properly with AVC
so, that's not cheap, and if you want to save some greenies, going to decent resistive attenuator is a way
take full package - that grounded thingie ( even if I can't fathom how they can sell attenuator without GND routed properly)
that small one is a toy, probably functional, but still a toy
Thank you for your answer Zen Mod.
I will gladly go to the stepped resistor type, have one small worry though.
Since my loudspeakers are super sensitive and I listen late at night, I am worried about the *only* 12 steps. I am almost sure this will not properly cover low volumes. And I listen at low volumes like 90% of the time.
There are volume pots with more (24?) steps but balanced operation requires 6 leads instead of 3 if I understand correctly and this limits the availability.
Perhaps someone with experience using a stepped design with high sensitivity speakers can comment on this usability issue.
Is 12 levels too little? What does a low-level listener like me do? Should I chose a different overall value of the pot (different scale) if that even exists?
Or is a resistor soldered in series with the pot a solution, assuming I never listen to full power?
PS1
Adding a resistor... is it in any way a solution that can be considered as identical with what is meant by "extra resistor" in the "requires" line of the table below (and if yes, what value? and where? in series with the speaker itself?):
source: this post
PS2
I must note that there is a detailed discussion here on diyaudio on the electronic and sonic differences between various solutions, but form my point of view I perceive it as a bit academic = I am interested in usability. What good does pure soud make if I cannot set the volume *exactly* to the power I need in order to continue listening? (without losing concentration if I write or read something and without having an angry spouse throw a pillow at me at 3AM)
Also of note is that the knob's clicking sounds when changing discrete values do not deter me. After all, my chair shifting and my footsteps also make quite non-hifi sounds when I get up to change the volume.
I will gladly go to the stepped resistor type, have one small worry though.
Since my loudspeakers are super sensitive and I listen late at night, I am worried about the *only* 12 steps. I am almost sure this will not properly cover low volumes. And I listen at low volumes like 90% of the time.
There are volume pots with more (24?) steps but balanced operation requires 6 leads instead of 3 if I understand correctly and this limits the availability.
Perhaps someone with experience using a stepped design with high sensitivity speakers can comment on this usability issue.
Is 12 levels too little? What does a low-level listener like me do? Should I chose a different overall value of the pot (different scale) if that even exists?
Or is a resistor soldered in series with the pot a solution, assuming I never listen to full power?
PS1
Adding a resistor... is it in any way a solution that can be considered as identical with what is meant by "extra resistor" in the "requires" line of the table below (and if yes, what value? and where? in series with the speaker itself?):
source: this post
PS2
I must note that there is a detailed discussion here on diyaudio on the electronic and sonic differences between various solutions, but form my point of view I perceive it as a bit academic = I am interested in usability. What good does pure soud make if I cannot set the volume *exactly* to the power I need in order to continue listening? (without losing concentration if I write or read something and without having an angry spouse throw a pillow at me at 3AM)
Also of note is that the knob's clicking sounds when changing discrete values do not deter me. After all, my chair shifting and my footsteps also make quite non-hifi sounds when I get up to change the volume.
Attachments
I appologize for the huge image, it used to be solvable by pressing F5, apparently this is because of a browser update. Sorry!
just a moment - visited again links you posted - even that resistive attenuator is declared as 600 Ohms
value that low is probably not a problem for your DAC ( being ladder etc. output, so low Rout) but hardly that your MM preamp could cope with 600R
you need to find balanced attenuator declared as 10K or 25K
and - pretty much avoid anything with less than 24 steps
avoid already assembled attenuators on e-bay, made with blue-white rotary switch
these switches as switches are not bad, but disassembly and lubing (either "graphite grease" of Vaseline) them is a must, if you want them to be durable
already assembled - you can't dismantle them for lubing
value that low is probably not a problem for your DAC ( being ladder etc. output, so low Rout) but hardly that your MM preamp could cope with 600R
you need to find balanced attenuator declared as 10K or 25K
and - pretty much avoid anything with less than 24 steps
avoid already assembled attenuators on e-bay, made with blue-white rotary switch
these switches as switches are not bad, but disassembly and lubing (either "graphite grease" of Vaseline) them is a must, if you want them to be durable
already assembled - you can't dismantle them for lubing
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