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HE-500, LCD2, D5000, DT770, SR80, on a speaker amp (Emotiva mini-X A-100) Project - Page 74

post #1096 of 3511
Quote:
Originally Posted by modulor View Post

 

Wouldn't adding the resistors to the +/- binding posts essentially act the same/similar as an attenuator? What would be your recommendation to counter gain to reduce noise floor/low hum? Time for me to do some more research =)

Err not really. The resistors is so that the Tube amp see the load (the he-6) as close to 8 ohm as possible. Transformer tube amp behave badly if the load isn't as tapped (8ohm/4ohm) - also long time usage without the resistor may damage the tranny. This is less important with SS amp. In fact I haven't found any SS amp that changes sound sig with a resistor attached.

 

The attenuator is used between the source and the preamp/integrated amp input. Basically it is to reduce the output of your source. Speaker amp has varied input sensitivity (mostly around 1.5V), and when fed with "too hot" source (think 3V RCA output), coupled with too high gain leading to virtually no volume control, or worse - distortion. Not all source has variable output, even when the source has variable output, the Alps pot/whatever volume control mechanic may affect the sound (reduced signal strength, distortion, noise, channel imbalance, impedance mismatch). The line attenuator is used to reduced the source output so that doesn't happen.

 

The other use for attenuator is that many preamps are more accurate/transparent at higher volume/higher position on the volume pot. The attenuator then is used to achieve that position.


Edited by khaine1711 - 5/7/13 at 1:40pm
post #1097 of 3511
Quote:
Originally Posted by khaine1711 View Post

Err not really. The resistors is so that the Tube amp see the load (the he-6) as close to 8 ohm as possible. Transformer tube amp behave badly if the load isn't as tapped (8ohm/4ohm) - also long time usage without the resistor may damage the tranny. This is less important with SS amp. In fact I haven't found any SS amp that changes sound sig with a resistor attached.

 

The attenuator is used between the source and the preamp/integrated amp input. Basically it is to reduce the output of your source. Speaker amp has varied input sensitivity (mostly around 1.5V), and when fed with "too hot" source (think 3V RCA output), coupled with too high gain leading to virtually no volume control, or worse - distortion. Not all source has variable output, even when the source has variable output, the Alps pot/whatever volume control mechanic may affect the sound (reduced signal strength, distortion, noise, channel imbalance, impedance mismatch). The line attenuator is used to reduced the source output so that doesn't happen.

 

The other use for attenuator is that many preamps are more accurate/transparent at higher volume/higher position on the volume pot. The attenuator then is used to achieve that position.

Gotcha...thanks for the detailed explanation, it's very helpful!

post #1098 of 3511

Yes, thanks for that khaine1711.

 

As an aside....

 

Steve Deckert (of Decware) produces a little 12AU7-based variable-gain tube buffer called the ZSTAGE, which he designed to be inserted in between a DAC (or pre-amp) and the amp, for the express purpose of changing the sound signature by varying the ratio of gain provided at the amp's inputs vs. gain provided at the amp's outputs.   

 

 

 

Quoting the Decware ZSTAGE Owner's Manual:

 

 

Quote:
RIDING THE GAIN - A term we came up with because of the active nature of the adjustment process that can take place when you use a ZSTAGE in conjunction with an preamp OR amplifier fitted with a gain control.
 
Riding the gain happens when you have two controls.  One at the source and one at the amp or preamp.  Think of it like water pressure.  You have a pipe with a valve at the input end and another valve at the output end.  The valves represent the gain controls and the pipe represents the signal path between the two gain gain controls. By turning up the input valve and turning the output valve down we create pressure inside the pipe.   By turning down (closing) the input valve and turning up (opening) the output valve we reduce pressure inside the pipe.  So if you took a garden hose and turned on the faucet you would have lots of water coming out the end, but it wouldn’t be able to spray anything until you put a nozzle on the end.  The nozzle acts like a valve to restrict the output causing the pressure in the hose to increase.     PRESSURE in this metaphor is the same thing as DYNAMICS in your stereo system.
 
By having a gain control at the source and a second one at the amp (or preamp) it is possible to manipulate the dynamics of your music and it’s overall frequency balance.  For example, if the music sounds thin you can increase the “pressure” by turning down the gain control on the amplifier (or preamp) and then raising the gain control at the source.  This will add noticeable weight to the music and mellow out the top end.   On the other side, if the music is sounding boomy or thick, you can do the opposite - turn up the gain on the amp and reduce the gain at the source.  The boominess will go away.

 

So it seems the ZSTAGE, having an adjustable output in the range 1 to 5 Vrms, can reduce dynamics by reducing the Vrms supplied to your amp's inputs (as you increase the gain at the amp's volume control to maintain a constant SPL at the headphones) -OR- it can increase dynamics by increasing the Vrms coming into the amp (as you decrease the gain at the amp's volume control to compensate).

 

This leads me to conjecture that a line-level attenuator would reduce dynamics at any desired SPL, while resistors placed at the amp's outputs would not.   In other words, don't use line-level attenuators if you want to avoid flattening the dynamics.

 

What do you think?

 

Thanks,

 

Mike

post #1099 of 3511
Quote:
Originally Posted by zilch0md View Post

Yes, thanks for that khaine1711.

 

As an aside....

 

Steve Deckert (of Decware) produces a little 12AU7-based variable-gain tube buffer called the ZSTAGE, which he designed to be inserted in between a DAC (or pre-amp) and the amp, for the express purpose of changing the sound signature by varying the ratio of gain provided at the amp's inputs vs. gain provided at the amp's outputs.   

 

 

So it seems the ZSTAGE, having an adjustable output in the range 1 to 5 Vrms, can reduce dynamics by reducing the Vrms supplied to your amp's inputs (as you increase the gain at the amp's volume control to maintain a constant SPL at the headphones) -OR- it can increase dynamics by increasing the Vrms coming into the amp (as you decrease the gain at the amp's volume control to compensate).

 

This leads me to conjecture that a line-level attenuator would reduce dynamics at any desired SPL, while resistors placed at the amp's outputs would not.   In other words, don't use line-level attenuators if you want to avoid flattening the dynamics.

 

What do you think?

 

Thanks,

 

Mike

 

It's not that clear cut. It really depends on the equipments and there's no general rule. By that logic, "hot dac" that cheats (i.e. outputting much higher Vrms than industry standard 2.25Vrms) should have killer dynamic - it's not. There's a lot more to this volume/preamp/amp and stuff than just Vrms and gain stages.

 

1. Inserting a buffer circuit between a preamp (active) and a power amp is a really bad idea. An active preamp will most likely add its own distortion/noise/compression (got its own buffer circuit), and adding another buffer will double that. You're better just grabbing an active preamp with tube rolling capabilities - still I think preamp should be as transparent as it gets. A buffer with variable gain is basically in essence an active preamp - albeit with lesser functionality (input/output/volume control). 

 

2. Attenuators do not always reduce dynamics. Most of the time people need an attenuator is that the system has too much gain; so it's either a preamp with too high gain/hot output, or a source putting too much Vrms in an integrated amp. Attenuating those signal will most likely not flatten dynamic. So yea you should not use attenuator as a volume control - we got passive/active preamp for that. What you should worry more about is that they add their own signature to the chain. No matter how small it is, that's still not good in the purist point of view.

post #1100 of 3511

Thank you khaine1171.  I appreciate your follow-up.

 

Mike

post #1101 of 3511

I just finished going through all 74 pages of this thread and am super psyched to get this amp for my HE500.  I currently have the O2/ODAC and compared the HE500s on my brother's ASUS Essence One.  There was a noticeable difference, which wasn't there with the HE400, AKG K702 65th Annies, Audio-Technica W1000X.  Where can this amp be purchased other than Emotiva and Amazon?  I'll probably just wait for another sale.

post #1102 of 3511
Quote:
Originally Posted by Limniscate View Post

I just finished going through all 74 pages of this thread and am super psyched to get this amp for my HE500.  I currently have the O2/ODAC and compared the HE500s on my brother's ASUS Essence One.  There was a noticeable difference, which wasn't there with the HE400, AKG K702 65th Annies, Audio-Technica W1000X.  Where can this amp be purchased other than Emotiva and Amazon?  I'll probably just wait for another sale.

 

As far as I know, only those 2 places. I remember when I got mines last year I read somewhere on their site that they only offered warranty on products purchased directly from them. It may have changed now, but might want to look that up to be on the safe side. Oh, and have fun with the Emotiva bigsmile_face.gif

post #1103 of 3511

Hmmm...this amp looks like a real treat. I am currently running my DACmini > LCD-2.2's and am pretty satisfied with the overall presentation. Sound is great...BUT...there seems to be a little lack of "oomph" and somewhat lean on the bass presence. A bit closed in. 

 

I'm thinking a beefier amp that would take the heavy lifting off the DACmini may be in order. It's 100% in the DAC department but maybe an amp like this is just what the doc ordered. 

 

Without reading all 74 pages, (working on it) anybody have a quick impression of a CEntrance DAC feeding the A-100 and some LCD-2's?

 

Thanks!

post #1104 of 3511
Quote:
Originally Posted by thegrobe View Post

Hmmm...this amp looks like a real treat. I am currently running my DACmini > LCD-2.2's and am pretty satisfied with the overall presentation. Sound is great...BUT...there seems to be a little lack of "oomph" and somewhat lean on the bass presence. A bit closed in. 

 

I'm thinking a beefier amp that would take the heavy lifting off the DACmini may be in order. It's 100% in the DAC department but maybe an amp like this is just what the doc ordered. 

 

Without reading all 74 pages, (working on it) anybody have a quick impression of a CEntrance DAC feeding the A-100 and some LCD-2's?

 

Thanks!

 

To keep it short, both my LCD-2.2 and HE-500 both work very well with the Emotiva. Plenty of bass here with the combo. Lack of bass quality/quantity should be the last concern with this amp. Plenty of other people have said the same thing. Don't know about your DAC but the amp in particular, but the  amp works.

post #1105 of 3511
Quote:
Originally Posted by Zoom25 View Post

 

To keep it short, both my LCD-2.2 and HE-500 both work very well with the Emotiva. Plenty of bass here with the combo. Lack of bass quality/quantity should be the last concern with this amp. Plenty of other people have said the same thing. Don't know about your DAC but the amp in particular, but the  amp works.

 

Also, the A-100 scales nicely with higher quality DACs. It has its limits obviously but they are all far past the 200USD of conventional HP amps :)

post #1106 of 3511

Quote:
Originally Posted by conquerator2 View Post

 

Also, the A-100 scales nicely with higher quality DACs. It has its limits obviously but they are all far past the 200USD of conventional HP amps :)

Good to know, as I most likely will be upgrading my DAC first before looking at other headphones and amps. What DACs have you tried Mini with?

 

I am currently looking at Mjolnir, Concero, Audiolab M-DAC, Yulong DA8, Nuwave...off the top. Still need to catch up on what's fresh nowadays in the DAC world.

post #1107 of 3511
Quote:
Originally Posted by Zoom25 View Post

Good to know, as I most likely will be upgrading my DAC first before looking at other headphones and amps. What DACs have you tried Mini with?

 

I am currently looking at Mjolnir, Concero, Audiolab M-DAC, Yulong DA8, Nuwave...off the top. Still need to catch up on what's fresh nowadays in the DAC world.

BMC PureDac, Auralic Ark MX+/VEGA, new Ayre QB-9, W4S Dac2 with the upgraded analog stage.

 

Also Mjonir is the amp - the Dac is Gungnir tongue_smile.gif

post #1108 of 3511
Quote:
Originally Posted by Zoom25 View Post

Good to know, as I most likely will be upgrading my DAC first before looking at other headphones and amps. What DACs have you tried Mini with?

 

I am currently looking at Mjolnir, Concero, Audiolab M-DAC, Yulong DA8, Nuwave...off the top. Still need to catch up on what's fresh nowadays in the DAC world.

 

Lots out there.  First thing is to set a budget.

post #1109 of 3511
Quote:
Originally Posted by khaine1711 View Post

BMC PureDac, Auralic Ark MX+/VEGA, new Ayre QB-9, W4S Dac2 with the upgraded analog stage.

 

Also Mjonir is the amp - the Dac is Gungnir tongue_smile.gif

 

Yeah, yeah...same schiit!biggrin.gif

 

Will look into them.

post #1110 of 3511
Quote:
Originally Posted by preproman View Post

 

Lots out there.  First thing is to set a budget.

 

I'm probably not going to be getting it anytime soon, so just looking into stuff right into for now. If I find something good, I don't mind waiting a bit more for it. Upgradititis isn't as strong as it used to be.

 

I would say depending on performance/value as well as features like balanced and pre-amp functions.

 

I guess anywhere from $500-1500 including taxes. Also priority given for stuff that I can get from Canada locally if possible.

 

Also anyone know any stores that sell Concero locally in Canada, since it's made in Canada.

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