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How can I run out of gain?


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In the previous thread from 2014 about Duntechs (which I have just read) it turns out that according to comments--by those who know--that an ME 1500 amp's driving ability was very satisfactory where an ME850 amp 'struggled' to drive these speakers adequately!

 

I cannot get my head around this--I have a high opinion of the driving ability of ME amps. If only a notional 100W is required according to the specs and written parameters of the speakers, and it seems that it is not too hard to drive (in theory),  then in the real world both amps 'should' be OK. As should the Pass amp and a host of other high-current contenders. 

 

Obviously that is not correct. Why, I remain uncertain. Considering my lack of technical knowledge anything could be responsible; I can see from all the comments here that something is preventing correct system synergy. And that certain high-current amps can drive the speakers adequately and others can't.

 

Here must be where theory gives way to practice--and reality?

 

 

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42 minutes ago, doogie44 said:

Obviously that is not correct. Why, I remain uncertain. Considering my lack of technical knowledge anything could be responsible; I can see from all the comments here that something is preventing correct system synergy. And that certain high-current amps can drive the speakers adequately and others can't.

 

Here must be where theory gives way to practice--and reality?

The combination of low impedance AND large phase angles means you're effectively driving insanely low impedances. The only way to get an idea of how low is to calculate the EDPR (equivalent peak dissipation resistance). Stereophile is the only review site that has begun doing so and to get an idea of how bad the situation really is, here is a review of the latest Wilson offering (which are notorious for being hard to drive).

https://www.stereophile.com/content/wilson-audio-specialties-sabrinax-loudspeaker-measurements

A good summary here is the following comment: "The SabrinaX has an EPDR of less than 2 ohms between 65Hz and 275Hz, with a minimum value of 1.1 ohms at 90Hz, where music can have high energy. "

These are meant to be 4 ohm speakers, but now you're talking about an amplifier that actually needs to be able to meaningfully drive and scale proportionately for 1 ohm. That's an insane load.

If you want a deep dive into understanding EDPR, here is the original article: https://www.stereophile.com/reference/707heavy/index.html

Edited by Ittaku
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51 minutes ago, aussievintage said:

 

Actually they have,  but as usual, it has been lost in the noise.

 

How did a question about gain turn into recommendations for arc welders (warning sarcasm)?

 

Hi @aussievintage 

Sorry I missed it. As in I have missed the answer.

(And this is not a sarcastic post, but an effort to understand)

Could you please  quote or post the answer.

Please and much appreciated.

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Guest Eggcup the Dafter
2 minutes ago, Ittaku said:

The combination of low impedance AND large phase angles means you're effectively driving insanely low impedances. The only way to get an idea of how low is to calculate the EDPR (equivalent peak dissipation resistance). Stereophile is the only review site that has begun doing so and to get an idea of how bad the situation really is, here is a review of the latest Wilson offering (which are notorious for being hard to drive).

https://www.stereophile.com/content/wilson-audio-specialties-sabrinax-loudspeaker-measurements

A good summary here is the following comment: "The SabrinaX has an EPDR of less than 2 ohms between 65Hz and 275Hz, with a minimum value of 1.1 ohms at 90Hz, where music can have high energy. "

These are meant to be 4 ohm speakers, but now you're talking about an amplifier that actually needs to be able to meaningfully drive and scale proportionately for 1 ohm. That's an insane load.

If you want a deep dive into understanding EDPR, here is the original article: https://www.stereophile.com/reference/707heavy/index.html

@davewantsmoore has already pointed out that we don't have any large phase angles here, assuming the given measurements are correct for this sample. Those specs surprised me given what I've heard about the Sovereigns.

The supersymmetry design in the Pass Lab amp is referred to elsewhere as a "special subset of bridging". I can't really tell if that is true or relevant but it's worth mentioning for those who can, I guess.

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9 minutes ago, Ittaku said:

A good summary here is the following comment: "The SabrinaX has an EPDR of less than 2 ohms between 65Hz and 275Hz, with a minimum value of 1.1 ohms at 90Hz, where music can have high energy. "

These are meant to be 4 ohm speakers, but now you're talking about an amplifier that actually needs to be able to meaningfully drive and scale proportionately for 1 ohm. That's an insane load.

 

I wonder what the upside is.  I mean, why make a speaker, heck, why BUY a speaker, that is so hard to drive.  

 

1 minute ago, Jventer said:

 

Hi @aussievintage 

Sorry I missed it. As in I have missed the answer.

(And this is not a sarcastic post, but an effort to understand)

Could you please  quote or post the answer.

Please and much appreciated.

 

I believe @stereo coffee and @davewantsmoore have provided the correct approach to understanding the question posed by this thread.

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On 28/03/2021 at 4:40 PM, kelossus said:

In terms of impedance? Nominal Impedance Variance, 4 ohms 3.0-4.5.

 

Haven't seen a graph showing phase angles or anything to determine how hungry they are but those old Dynaudio woofers need a heap of current to get them going. The magnet is so undersized so I think they really on current to make anything happen. Seriously I am drinking a cup of coffee and it's substantially heavier than the magnetic assembly on the 12" Dyn.

Don't let those aluminium voice coils fool you.  They weight much less than copper but can handle more power/heat.

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15 minutes ago, Eggcup the Dafter said:

The supersymmetry design in the Pass Lab amp is referred to elsewhere as a "special subset of bridging". I can't really tell if that is true or relevant but it's worth mentioning for those who can, I guess.

This is very interesting, as regular bridging of an amplifier makes it less able to cope with impedances as it effectively doubles the minimum impedance.

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16 minutes ago, aussievintage said:

I wonder what the upside is.  I mean, why make a speaker, heck, why BUY a speaker, that is so hard to drive. 

I believe the vast majority of buyers simply aren't aware of how hard they are to drive, and they can just get away with it because they always have. It makes for really good measurements and numbers but has done so at huge compromise in other ways that till now haven't shown up in numbers anywhere. There's also a kind of arse-backwards appeal to something that needs expensive and ballsy amplifiers.

Edited by Ittaku
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2 hours ago, Jventer said:

Is it not  amazing

 

Sure....  but there's not really enough known about the problem to say for sure what is going on.

 

The system has lower than typical gain, yes.... but it's not clear enough if simply lack of max level is the issue...or bad sound when it is reached.... or what that max level is.

 

2 hours ago, Jventer said:

 

As much as he protests otherwise.... I don't see that anybody isn't listening to him.     Yes, it could very well be that the amplifier isn't big enough.....   but there isn't enough information to tell.

 

He and others report that they like driving the speakers with big amplifiers.... great - I don't doubt them......  but the reason isn't that this is a challenging electrical load.

 

... but again, that doesn't mean he's not wrong about the amp (size).  The speaker will take a lot of power without sounding bad..... and the poster might be asking too much.......  (that being said, based on the description I suspect it is something else.... but it's hard to be sure because not enough info is provided).

 

 

2 hours ago, Jventer said:
  • contacting Simon at VAF as he worked for Duntech and may just be able to sell/source you the right amp and or advise re pre or both
  • contact Kiat that also worked at Duntech and are now selling a new Duntech range

 

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Guest Eggcup the Dafter
1 hour ago, Ittaku said:

This is very interesting, as regular bridging of an amplifier makes it less able to cope with impedances as it effectively doubles the minimum impedance.

True, but would the minimum impedance in this case come up as high as 2.9 Ohms? I suppose it's possible, it doesn't seem likely.

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2 hours ago, aussievintage said:

How did a question about gain turn into recommendations for arc welders (warning sarcasm)?

 

People recommend large amps and/or that the Pass might not be up to it..... and while they might not be wrong ..... the (technical) reasons behind their recommendations were misguided.

 

.... and so it digressed into how would you actually figure out if it were the power amplifier clipping.... or what logic would you use to recommended a "massive amp", etc.

 

When peoples experience contradicts basic physics which has been settled for ages longer than anybody here has been alive .....  it isn't because the "physics doesn't apply".    It just means that there's another/different reason (which doesn't contradict basic physics).   :) 

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2 hours ago, doogie44 said:

In the previous thread from 2014 about Duntechs (which I have just read) it turns out that according to comments--by those who know--that an ME 1500 amp's driving ability was very satisfactory where an ME850 amp 'struggled' to drive these speakers adequately!

 

To what level.  That absolutely could be true if you were pushing these speaker to beyond ~115dB@1m ... where the approximately the ME850 would clip.  700w@4ohm

 

2 hours ago, doogie44 said:

If only a notional 100W is required according to the specs and written parameters of the speakers, and it seems that it is not too hard to drive (in theory),  then in the real world both amps 'should' be OK

 

100w would take them to about ~ 105dB@1m.... it just depends on what level you want.

 

2 hours ago, doogie44 said:

 

. As should the Pass amp and a host of other high-current contenders. 

I mean it doesn't even need anything particularly high current, 4ohms quite flat isn't difficult.....  just an amp genuinely engineered to handle 4ohm, with enough power for the SPL is all that's needed.

 

2 hours ago, doogie44 said:

Obviously that is not correct. Why

 

Perhaps people play these speakers to high watts/1m ....  because a) they have low distortion (so don't sound "loud"), and b) because they sit far away from them.

 

 

2 hours ago, doogie44 said:

preventing correct system synergy

 

Probably the preamp being crud, and/or not driving the power amp to full power ..... or the power amp isn't big enough, if he's trying to drive the speakers quite loud.

 

2 hours ago, doogie44 said:

And that certain high-current amps can drive the speakers adequately and others can't.

Given the previous amp only offered ~3dB more power ..... then I'd guess it the gain structure.

 

The DAC puts out a small signal.... and the preamp doesn't amplify it much.... as so the power amp isn't being driven to full power.    But more information would help rule things in/out.

 

2 hours ago, doogie44 said:

Here must be where theory gives way to practice--and reality?

 

No it just mean there isn't enough info.    When whatever is going on is figured out, you will see that no theory is contradicted ;)

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1 hour ago, Eggcup the Dafter said:

Those specs surprised me given what I've heard about the Sovereigns.

 

I was the opposite.   I would have been shocked and disappointed from what I know about the heritage if this speaker had of been particularly inefficient and/or reactive load.

 

That doesn't mean people don't like driving them with large amps.....  cos they turn it up loud and sit back.   Low distortion speakers don't sound "loud" ;) 

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2 hours ago, Ittaku said:

This is very interesting, as regular bridging of an amplifier makes it less able to cope with impedances as it effectively doubles the minimum impedance.

 

It's their patent name for a kind of "balanced amplifier", not really "bridged".

 

That being said, I had a quick read of the manual.... and it does make special mention of wanting to be driven by a symmetrical balanced signal (ie. pin 2 and 3 containing equal signals of opposite phase).

 

From what I remember about the PS audio stuff their designer does interesting things with their balanced signal.....  perhaps it is "unbalanced balanced" if you know what I mean    <shrug>.

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1 minute ago, davewantsmoore said:

 

It's their patent name for a kind of "balanced amplifier", not really "bridged".

Reading further, that looks right.

 

10 minutes ago, davewantsmoore said:

From what I remember about the PS audio stuff their designer does interesting things with their balanced signal.....  perhaps it is "unbalanced balanced" if you know what I mean    <shrug>.

Without reading back, I believe Kelossus is using an unbalanced connection between pre and power though., and from the TT as well.

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3 minutes ago, Eggcup the Dafter said:

Reading further, that looks right.

 

Without reading back, I believe Kelossus is using an unbalanced connection between pre and power though., and from the TT as well.

Correct at the moment I am. I do usually run balanced between the pre and power but I am waiting delivery of the cables.

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2 hours ago, Eggcup the Dafter said:

@davewantsmoore has already pointed out that we don't have any large phase angles here, assuming the given measurements are correct for this sample. Those specs surprised me given what I've heard about the Sovereigns.

The supersymmetry design in the Pass Lab amp is referred to elsewhere as a "special subset of bridging". I can't really tell if that is true or relevant but it's worth mentioning for those who can, I guess.

No, sorry but that's misquote:https://www.passlabs.com/wp-content/uploads/2020/05/x3_om.pdf

"The supersymmetric amplifier is a special subset of balanced amplifiers, unique and covered by U.S. patent."

The Pass Labs stuff can run quite well on 2ohms -https://www.stereophile.com/content/pass-labs-xa305-power-amplifier-measurements

I was actually was running my XA25 on 1.5ohms for a while. Not knowing that one of the bypassed capacitors had shorted in my midrange driver on one side. I worked it out as it was cutting the one channel when I was driving at about 95dB+. Otherwise, it worked just fine at less anti-social volumes.

Edited by deepthought
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I was/am one of the arc welder advocates in this thread. 

 

To clarify, my comments were in relation to suggestion that the base was soft and not tight. This is different to an overall loudness issue assuming the levels were similar between the amps and is different from gain issues.

 

I've had higher wattage amps with soft base and lower wattage amps with tight base but with high current capability. My thoughts are that my higher wattage amp 'clipped' base from lack of instantaneous current capability.

 

Back to the OP and discussion, I'm not clear on whether overall loudness is the issue (gain) or lack of tight base (potential amp limiting in current or slew) . Or whether the lack of tight base is making the level feel lower than it is so the levels are actually higher and then causing further 'clipping' of base. 

 

 

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Guest Eggcup the Dafter
1 hour ago, deepthought said:

No, sorry but that's misquote:https://www.passlabs.com/wp-content/uploads/2020/05/x3_om.pdf

"The supersymmetric amplifier is a special subset of balanced amplifiers, unique and covered by U.S. patent."

The Pass Labs stuff can run quite well on 2ohms -https://www.stereophile.com/content/pass-labs-xa305-power-amplifier-measurements

I was actually was running my XA25 on 1.5ohms for a while. Not knowing that one of the bypassed capacitors had shorted in my midrange driver on one side. I worked it out as it was cutting the one channel when I was driving at about 95dB+. Otherwise, it worked just fine at less anti-social volumes.

 i wasn't quoting the manual here, but another article about these amps which used the term "bridging". to describe these amps. There is more than one "amplifier" per channel in these amps as I read it (simplification) but they are not bridged. I brought it up initially because i hadn't understood this properly.

 

Interesting that you mention instantaneous current... since the manual suggests the opposite. I've always understood that these issues are caused by the failure to maintain continuous current.

 

Never judge one amplifier by the performance of another from the same manufacturer, by the way. You're probably right this time but I fell into that particular trap once;

 

 

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Guest Eggcup the Dafter
1 hour ago, DrSK said:

I was/am one of the arc welder advocates in this thread. 

 

To clarify, my comments were in relation to suggestion that the base was soft and not tight. This is different to an overall loudness issue assuming the levels were similar between the amps and is different from gain issues.

 

I've had higher wattage amps with soft base and lower wattage amps with tight base but with high current capability. My thoughts are that my higher wattage amp 'clipped' base from lack of instantaneous current capability.

 

Back to the OP and discussion, I'm not clear on whether overall loudness is the issue (gain) or lack of tight base (potential amp limiting in current or slew) . Or whether the lack of tight base is making the level feel lower than it is so the levels are actually higher and then causing further 'clipping' of base. 

 

 

I reached that conclusion as well, but through "audiophile lore". Once again, not to be fully trusted.

Either problem will be solved by a power amp with more current and more gain, so "MORE POWER" becomes a kind of default answer. If I had a dollar for the number of times I've heard and read that you can "never have too much power" I could retire happily
But is it the best or smartest solution? You could have a dud preamp, a nicely heated room in summer, and a hefty power bill.

 

(The reason I have the PM-10 isn't "more power, but because  my wife said she wanted a good disc player, I chose the SA-10 and she then  said "get the matching amplifier". Smart? Compare and contrast...)

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15 minutes ago, Eggcup the Dafter said:

Either problem will be solved by a power amp with more current and more gain, so "MORE POWER" becomes a kind of default answer. If I had a dollar for the number of times I've heard and read that you can "never have too much power" I could retire happily

Perhaps it's time we changed the vernacular to "You can never have too much current?"

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