Multi-Amping

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Welborne

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Re: Multi-Amping
« Reply #20 on: 20 Jul 2009, 08:57 pm »

dear 1000a, I have both 90watt and 130watt ps. After you have compared them, you won't go back to 90watt one. You may not be able to hear a very big difference if your speakers are very sensitive in the range of 93db-100db, but when you are using them to drive less sensitive loudspeakers, the difference is not so funny. :nono:

Are you running mono amps?  Thanks, 1000a

No, i only have one Virtue 2. I am powering them with the 130w ps.

dcolak

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Re: Multi-Amping
« Reply #21 on: 22 Aug 2009, 03:05 pm »
First, there was one two...



...now they are two:



:lol:


Cheerwino

Re: Multi-Amping
« Reply #22 on: 22 Aug 2009, 03:21 pm »
 :thumb:
Do you find the red to sound a little warm and the white to be cooler?
 :lol:

dcolak

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Re: Multi-Amping
« Reply #23 on: 22 Aug 2009, 04:07 pm »
:thumb:
Do you find the red to sound a little warm and the white to be cooler?
 :lol:

Hm... using one per channel, the sound is more metalic... more harsh... with less bass... very hard to listen to, all the sweetness is gone...

The combination simply sounds... bad :(

It is strange, I expected quite the opposite!  :scratch:

Maybe the new one is still not broken in and is masking the old one... :?

Welborne

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Re: Multi-Amping
« Reply #24 on: 23 Aug 2009, 04:15 pm »
:thumb:
Do you find the red to sound a little warm and the white to be cooler?
 :lol:

Hm... using one per channel, the sound is more metalic... more harsh... with less bass... very hard to listen to, all the sweetness is gone...

The combination simply sounds... bad :(

It is strange, I expected quite the opposite!  :scratch:

Maybe the new one is still not broken in and is masking the old one... :?

Yes, I find this result strange as I have thought about setting up something similar a while ago too....something wrong with the phase connection?

Cheerwino

Re: Multi-Amping
« Reply #25 on: 23 Aug 2009, 10:47 pm »
I have had success running two Virtue Ones as monos with the 30v/90w supplies and they rocked. Didn't run them through a pre-amp or anything.

panomaniac

Re: Multi-Amping
« Reply #26 on: 24 Aug 2009, 12:00 pm »
No reason it should sound worse.  I would check polarity for sure.  Do you have a test tone or track for that?

dcolak

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Re: Multi-Amping
« Reply #27 on: 24 Aug 2009, 03:43 pm »
No reason it should sound worse.  I would check polarity for sure.  Do you have a test tone or track for that?

Polarity is OK. :thumb:

It sounds as if the distortion levels are higher when using just one channel (sound is harder, you can't listen to it with high volume for too long).

Connect two speakers to the amp and the sound gets in order...

I've checked the clipping LED and it does light up at the exact same spot as it does with both speakers driven.

Shouldn't it begin to clip a bit later, now driving just one speaker?  :scratch:

panomaniac

Re: Multi-Amping
« Reply #28 on: 24 Aug 2009, 10:55 pm »
No, clipping is a function of the input signal and nothing else.

I'm surprised this doesn't work for you.  It works great for me and many other Virtue owners.   Wonder what's going on......

dcolak

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Re: Multi-Amping
« Reply #29 on: 25 Aug 2009, 12:01 am »
No, clipping is a function of the input signal and nothing else.

I'm surprised this doesn't work for you.  It works great for me and many other Virtue owners.   Wonder what's going on......

The lack of bass could be seen as better controlled lows?

Speakers are Klipsch RF83, 100db/2.83v/1m sensibility (8ohm nominal).

I also tried JBL S312II (92db/1m/2.83v 8ohm).

Maybe the new Two just needs more break-in.

I'm making it sweat as we speak :)


panomaniac

Re: Multi-Amping
« Reply #30 on: 25 Aug 2009, 12:44 pm »
The lack of bass could be seen as better controlled lows?

Very possible.  A lot of effiecient bass speakers actually need a low damping factor amp to get any bass at all.  Think tube amps.   With something like the klipsch, you might test some series resistance to lower the damping factor and restore tonal balance.  Anything from 1/2 an ohm up to ~4 ohms.   I've had to do it with some speakers.

Welborne

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Re: Multi-Amping
« Reply #31 on: 25 Aug 2009, 04:48 pm »
A lot of effiecient bass speakers actually need a low damping factor amp to get any bass at all.
------------

This is what I have in mine too. This phenomenon exist and is especially more obvious on some speakers than others. For example, My east german Schulz coaxial speakers definitely respond much better to tube amp with much lower damping factor. You can hear a very "hard" bass like hammering, kind of ONE note thing, but with tube amp that has much smaller power, the bass is deep and textured. But on other speakers, I like Virtue more than the tube amp..

Cheerwino

Re: Multi-Amping
« Reply #32 on: 25 Aug 2009, 05:05 pm »
The lack of bass could be seen as better controlled lows?

Very possible.  A lot of effiecient bass speakers actually need a low damping factor amp to get any bass at all.  Think tube amps.   With something like the klipsch, you might test some series resistance to lower the damping factor and restore tonal balance.  Anything from 1/2 an ohm up to ~4 ohms.   I've had to do it with some speakers.

This must be why my Horn Shoppe Horns don't make much bass with the Virtue One. I use a sub to fill in, so it's not a problem and it sounds really sweet in the mids and highs. But, it is much 'bassier' with the 30v/130w PS than the 90w PS.

How would you go about adding resistance, Michael? I'm not a DIY/techie type, so I'd have to get someone else to do it. But, I'm curious to know what is involved, if you could explain--and what the trade offs might be.

Thanks,

Guy

Welborne

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Re: Multi-Amping
« Reply #33 on: 25 Aug 2009, 06:39 pm »
The lack of bass could be seen as better controlled lows?

Very possible.  A lot of effiecient bass speakers actually need a low damping factor amp to get any bass at all.  Think tube amps.   With something like the klipsch, you might test some series resistance to lower the damping factor and restore tonal balance.  Anything from 1/2 an ohm up to ~4 ohms.   I've had to do it with some speakers.

This must be why my Horn Shoppe Horns don't make much bass with the Virtue One. I use a sub to fill in, so it's not a problem and it sounds really sweet in the mids and highs. But, it is much 'bassier' with the 30v/130w PS than the 90w PS.

How would you go about adding resistance, Michael? I'm not a DIY/techie type, so I'd have to get someone else to do it. But, I'm curious to know what is involved, if you could explain--and what the trade offs might be.

Thanks,

Guy

I learned this from Michael quite some time ago. You just insert a resistor between either + or - of your speaker cable , and the speaker's input socket. (not across + and -, becareful). This has the effect of adding resistance to the chain and mathematically increase the output impedance of your amp. Other things being equal, the higher the output impedance of your amp, the lower the damping factor it will see. But make sure you choose to use a higher "wattage" resistor, 10w would be a good start. Nelson Pass did this kind of trick when he published a paper on SS amp and efficient fullrange (mostly lowther and fostex) a while back.

Michael, correct me if I am wrong here. :duh: :duh: :roll:

Welborne

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Re: Multi-Amping
« Reply #34 on: 25 Aug 2009, 07:01 pm »
another way is to use those "old and ugly" speaker cable like those from Klangfilm/Western Electric time which often has a higher resistance than modern cables

panomaniac

Re: Multi-Amping
« Reply #35 on: 26 Aug 2009, 02:43 pm »
You are correct!  Series resistance is what you want.  Use a 10 watt resistor made for crossovers and you will have no problems.

With a series resistor you can change to tonal balance of some speakers.  The lower the Qts of the bass driver and the higher the damping factor of the amp, the more difference the resistor will make.  Both the low Qts and the high damping factor in the amp are indications of  "damping".  You can lower that damping with the resistor.   Very thin cables can have the same effect.  So the woofer is not do tightly controlled.  Sometimes needed to get any bass at all.

Cheerwino

Re: Multi-Amping
« Reply #36 on: 6 Sep 2009, 03:49 am »
You are correct!  Series resistance is what you want.  Use a 10 watt resistor made for crossovers and you will have no problems.

With a series resistor you can change to tonal balance of some speakers.  The lower the Qts of the bass driver and the higher the damping factor of the amp, the more difference the resistor will make.  Both the low Qts and the high damping factor in the amp are indications of  "damping".  You can lower that damping with the resistor.   Very thin cables can have the same effect.  So the woofer is not do tightly controlled.  Sometimes needed to get any bass at all.

Thanks fellas.  :notworthy: I see many kinds of 10w resistors here at Parts Express. What ohm do I need? :dunno: http://www.parts-express.com/wizards/searchResults.cfm?FTR=10w+resistor&search_type=main&WebPage_ID=3&searchFilter=10w+resistor&x=0&y=0

I'm using the Virtue One with 30v/130w PS into Horn Shoppe rear loaded Horn speakers with a 4" Fostex driver. I understand the Horns like low damping. In the Nelson Pass article on damping, he mentions 47 ohm resistors and then states you'll want a solid state amp of 300w and use 50w resistors for his experiment.    :dunno:

BTW, here's that Nelson Pass article to which Welborne referred, in case anyone is interested:http://www.firstwatt.com/downloads/cs-amps-speakers.pdf

panomaniac

Re: Multi-Amping
« Reply #37 on: 6 Sep 2009, 03:57 pm »
What Nelson is talking about with the 47R resistor is a little different.  He's turning a voltage source amp (like the Virtue) into a current source amp.  I do NOT recommend this with the Virtue unless you have an impedance compensation circuit.
The Virtue is not designed to run into a high impedance load.

Cheerwino

Re: Multi-Amping
« Reply #38 on: 6 Sep 2009, 05:29 pm »
Ah.

panomaniac

Re: Multi-Amping
« Reply #39 on: 6 Sep 2009, 08:03 pm »
But don't lose hope!  If I get a little time, I will try to come up with a simple circuit that will let you turn the Virtue into a current source amp.