"HISSSS"

[kiwiemo]

Sooo, since my last issue, of killing a pair of KEF R900's, I got down on a deal from a local Martian Logan dealer and have set up a pair of motion 40's. These speakers run a sensitivity of 92db.... Where as the KEF were running 90db....as far as specs go the rest is much of a muchness, although I wouldn't put the two on the same level, as I see it.
The issue here is the XPA-1 monos noise floor is far more audible with the ML 40s. The hiss was there with the KEFs but very very low, as in not heard in the music. Totally different situation with the ML40s that said its not with every CD.
Can this issue be 'reduced' with a power conditioner?
Any help/information would be great

Cheers Kiwiemo

[Priapulus]

You should have _no_ audible hiss, hum or distortion with modern equipment. If you can hear it, something is broken or improperly installed.
Sorry,
/blair

[Jim]

If you disconnect your preamp or whatever line source you have connected to the XPA-1 - do you still have hiss?

[Jim]

Jun 10, 2017 20:07:34 GMT -5 Priapulus said:

You should have _no_ audible hiss, hum or distortion with modern equipment. If you can hear it, something is broken or improperly installed.
Sorry,
/blair

I mostly agree, except for high sensitivity speakers. Much much harder to eliminate hiss on very sensitive speakers even with proper gear.

...but 92db isn't sensitive.

[novisnick]

Jun 10, 2017 20:07:34 GMT -5 Priapulus said:

You should have _no_ audible hiss, hum or distortion with modern equipment. If you can hear it, something is broken or improperly installed.
Sorry,
/blair

I tend to agree, something is amiss! 
Please list your gear and how it's connected.

[kiwiemo]

Jun 10, 2017 20:17:22 GMT -5 Jim said:

If you disconnect your preamp or whatever line source you have connected to the XPA-1 - do you still have hiss?

Yeah the hiss is there with only the speaker(s) connected to the monoblock.

[kiwiemo]

Jun 10, 2017 20:19:00 GMT -5 novisnick said:

Jun 10, 2017 20:07:34 GMT -5 Priapulus said:

You should have _no_ audible hiss, hum or distortion with modern equipment. If you can hear it, something is broken or improperly installed.
Sorry,
/blair

I tend to agree, something is amiss! 
Please list your gear and how it's connected.

Ok here it is
Marantz SA8005
Monster 400 RCA to
XSP-1 gen 2
Emotiva XLR to
XPA-1 gen 3
All powered with ISOTEK EVO3 from the wall outlet, which are only powering the gear. We also run 230v in New Zealand.
I also run, wait for it......an iPhone 4s as my MP3/USB input.
Hope this helps.

Kiwiemo

[vneal]

Something is amiss. Silence from equipment.
And anything above 88db is sensitive

[leonski]

I don't know where this leaves 'ya, but
Gain for amp is 29db.
SNR is 89db at ONE WATT which is where you'll be nearer than full power virtually ALL of the time.

What is different about the CDs which don't have hiss? Louder? Few or no Quiet parts in the music? Since you have hiss with only speakers connected to amp, that pretty
much cuts it, don't you think? The hiss MUST be there all the time, just masked by louder music, right?

You are building a SYSTEM here, not just buying 'stuff' to fill a slot.

You MIGHT try unplugging other stuff in the house. A 15 amp circuit is too little for a pair of those large Monoblocs. Especially when everything ELSE is plugged in, too. Maybe turn other stuff off and especially check for the awful light dimmer, fish tank pump and maybe some appliances. This is a long shot.

[klinemj]

What level is your preamp set at when you hear the hiss?

Mark

[leonski]

Jun 10, 2017 21:56:40 GMT -5 kiwiemo said:

Jun 10, 2017 20:17:22 GMT -5 Jim said:

If you disconnect your preamp or whatever line source you have connected to the XPA-1 - do you still have hiss?

Yeah the hiss is there with only the speaker(s) connected to the monoblock.

This really limits the possibilities.

[deltadube]

Jun 10, 2017 19:55:49 GMT -5 kiwiemo said:

Sooo, since my last issue, of killing a pair of KEF R900's, I got down on a deal from a local Martian Logan dealer and have set up a pair of motion 40's. These speakers run a sensitivity of 92db.... Where as the KEF were running 90db....as far as specs go the rest is much of a muchness, although I wouldn't put the two on the same level, as I see it.
The issue here is the XPA-1 monos noise floor is far more audible with the ML 40s. The hiss was there with the KEFs but very very low, as in not heard in the music. Totally different situation with the ML40s that said its not with every CD.
Can this issue be 'reduced' with a power conditioner?
Any help/information would be great

Cheers Kiwiemo

I HAVE HEARD ZERO HISS WITH MY XPA 1S

LUCKY ME...

[kiwiemo]

Jun 11, 2017 0:09:52 GMT -5 leonski said:

I don't know where this leaves 'ya, but
Gain for amp is 29db.
SNR is 89db at ONE WATT which is where you'll be nearer than full power virtually ALL of the time.

What is different about the CDs which don't have hiss? Louder? Few or no Quiet parts in the music? Since you have hiss with only speakers connected to amp, that pretty
much cuts it, don't you think? The hiss MUST be there all the time, just masked by louder music, right?

You are building a SYSTEM here, not just buying 'stuff' to fill a slot.

You MIGHT try unplugging other stuff in the house. A 15 amp circuit is too little for a pair of those large Monoblocs. Especially when everything ELSE is plugged in, too. Maybe turn other stuff off and especially check for the awful light dimmer, fish tank pump and maybe some appliances. This is a long shot.

The 'hiss' is there always, all be it you have to get up real close to the tweeter to hear it when no music is not on, when you put a cd on it becomes more, way more pronounced. Some recordings seem to be worse. Not sure why that is.
There are no dimmer switches or fish tank pumps in this house. Not sure it helps but light and power here are inderpendent, a completely different circuit system. Most power outlets here are 20amps(I believe), but is that the problem?
Yes I'm trying to build a system, it seems the problem is the amps:(

Kiwiemo

[kiwiemo]

Jun 11, 2017 0:20:18 GMT -5 klinemj said:

What level is your preamp set at when you hear the hiss?

Mark

It's there at all levels, if you crank it up you can drown it! Not really the answer however

Kiwiemo

[klinemj]

Jun 11, 2017 0:54:15 GMT -5 kiwiemo said:

Jun 11, 2017 0:20:18 GMT -5 klinemj said:

What level is your preamp set at when you hear the hiss?

Mark

It's there at all levels, if you crank it up you can drown it! Not really the answer however

Kiwiemo

That's odd...even at -20 or so?

Mark

[leonski]

The reason I bring up power is that you likely have 2 amps with 1200va transformers AND a bunch of other stuff on a house circuit.
20 amp doesn't matter in this case, because all house circuits are derated 20% for continuous use.    Like space heaters.   
A 20 amp circuit will have 1 'hole' for ground, one straight plug for neutral (?) and 2 slots at right angles for hot.   If you only have a straight up and down
pair of slots, it's a 15 amp circuit even IF wired with 12 or better and a 20 amp breaker.   The PLUG is than than limit.  

I just think that IF you are going to the expense of a real high power pair of amps, you might as well be actually able to USE it.  

'Stats, huh?    They plug in, right?    Might be something to look into.   

[kiwiemo]

Jun 11, 2017 0:38:06 GMT -5 deltadube said:

Jun 10, 2017 19:55:49 GMT -5 kiwiemo said:

Sooo, since my last issue, of killing a pair of KEF R900's, I got down on a deal from a local Martian Logan dealer and have set up a pair of motion 40's. These speakers run a sensitivity of 92db.... Where as the KEF were running 90db....as far as specs go the rest is much of a muchness, although I wouldn't put the two on the same level, as I see it.
The issue here is the XPA-1 monos noise floor is far more audible with the ML 40s. The hiss was there with the KEFs but very very low, as in not heard in the music. Totally different situation with the ML40s that said its not with every CD.
Can this issue be 'reduced' with a power conditioner?
Any help/information would be great

Cheers Kiwiemo

I HAVE HEARD ZERO HISS WITH MY XPA 1S

LUCKY ME...

Yes indeed, lucky you, what is it you have I do not, other than faulty amps??
Kiwiemo

[kiwiemo]

Jun 11, 2017 2:39:14 GMT -5 leonski said:

The reason I bring up power is that you likely have 2 amps with 1200va transformers AND a bunch of other stuff on a house circuit.
20 amp doesn't matter in this case, because all house circuits are derated 20% for continuous use.    Like space heaters.   
A 20 amp circuit will have 1 'hole' for ground, one straight plug for neutral (?) and 2 slots at right angles for hot.   If you only have a straight up and down
pair of slots, it's a 15 amp circuit even IF wired with 12 or better and a 20 amp breaker.   The PLUG is than than limit.  

I just think that IF you are going to the expense of a real high power pair of amps, you might as well be actually able to USE it.  

'Stats, huh?    They plug in, right?    Might be something to look into.   

To give an idea of how things are here, our wall outlets are a 3 pin set up 'positive/hot' negitive/neutral' and 'earth/ground'. Not all appliances have to have an earth/ground, but for this set up they do. And most important on this the circuit in to the room with the system is on its own from the switch board. Soo that said, the 'hiss' is produced from the amp.
Kiwiemo

[kiwiemo]

Jun 11, 2017 0:56:32 GMT -5 klinemj said:

Jun 11, 2017 0:54:15 GMT -5 kiwiemo said:

It's there at all levels, if you crank it up you can drown it! Not really the answer however

Kiwiemo

That's odd...even at -20 or so?

Mark

Yup at -20

[klinemj]

This is odd...is it a hiss or a hum? Can you record a video and share it so we can here it?

Mark