STA-9

duke of dorkdom · « **Reply #40 on:** 17 Apr 2016, 05:12 pm »

edit: "Curious why power does NOT "double down""

rustydoglim · « **Reply #41 on:** 17 Apr 2016, 08:08 pm »

Quote from: duke of dorkdom on 17 Apr 2016, 05:08 pm

Curious why power does "double down"

What do you mean?

KLH007 · « **Reply #42 on:** 18 Apr 2016, 01:33 pm »

I think the "Duke" is asking why the power output doesn't double into 4 ohm loads, instead of being the same as 8 ohm level?

duke of dorkdom · « **Reply #43 on:** 19 Apr 2016, 12:02 pm »

correct. A power rating that stays the same while the load impedance is lowered is, to me, unusual outside of tubes. Not a knock or anything, just honestly curious why this is. Was it by design?

roscoeiii · « **Reply #44 on:** 19 Apr 2016, 02:43 pm »

Quote from: duke of dorkdom on 19 Apr 2016, 12:02 pm

correct. A power rating that stays the same while the load impedance is lowered is, to me, unusual outside of tubes. Not a knock or anything, just honestly curious why this is. Was it by design?

IIRC, and I am not a technical science guy, but Class D (or just some Class D) does not double down (or increase as a Class A or A/B amp would) into 4 Ohms.

rustydoglim · « **Reply #45 on:** 20 Apr 2016, 06:53 pm »

This question was asked in another topic and I am sure it will come up. Here's the answer that non tech person can understand
http://www.nuprimeaudio.com/index.php/reviews/faq.html#faq_18

In short, it doesn't double down is because 1) we are conservative in our spec and 2) the power supply is the limiting factor, nothing to do with the amp. More power = more cost also (amp also has to scale up) = bigger amp = NOT IDA-8 anymore

larsg · « **Reply #46 on:** 21 Apr 2016, 11:06 am »

Tried to use 2 STA-9 in bridged mono but the volume level was not equal on both. How to match volume level ??

John Casler · « **Reply #47 on:** 22 Apr 2016, 05:28 am »

Quote from: larsg on 21 Apr 2016, 11:06 am

Tried to use 2 STA-9 in bridged mono but the volume level was not equal on both. How to match volume level ??

Hi Lars,

Sure that is not normal, so something is either not working correctly, the system is not hooked up correctly, or a source or preamp issue is causing it.

To see if it is an amp issue, simply reverse the L&R channels and if it switches to the other amp the issue is not amp related.

If it does stay with one of the amps, then check all amp connections and bridging switches are set correctly.

And it goes without saying, but if you are using an RCA on one channel and an XLR on the other, the XLR will be louder and the RCA softer, but you already knew this.

larsg · « **Reply #48 on:** 22 Apr 2016, 07:31 am »

Tried all you mention and it,s down to the Amps. It,s not a big difference but enough to irritate.

rustydoglim · « **Reply #49 on:** 22 Apr 2016, 09:58 pm »

Did you try to use a Decible Meter app (there are free apps) or the smartphone to measure the sound level ?
If they are measured differently, we can fix or exchange for you.

larsg · « **Reply #50 on:** 23 Apr 2016, 04:23 pm »

It was 5 Db diffrence between the two STA-9
Pink noise , HPA-9 , RCA too STA-9 in mono mode. Ran the test tree times on STA-9 Nr. 1 , plugged it out and plugged Nr. 2 inn and ran the test 3 times again without toutching anyting. Nr. 1 69/70 Db Nr. 2 74/75 Db everytime.

Armaegis · « **Reply #51 on:** 23 Apr 2016, 06:53 pm »

A 6dB difference is a rather common gain setting difference and also corresponds to a double/half voltage. It also corresponds to the typical difference between balanced/unbalanced signals. Are all the switches set correctly at the back?

larsg · « **Reply #52 on:** 23 Apr 2016, 09:56 pm »

All the switches was set correctly. But as a last try I moved the mono switch up and down many times and finally it "clicked" in place and both STA-9 was at 74/75 Db.
Never gonna touch it again !!
Kenwood KD-64F + HPA-9 + ST-10 + JBL 4312E on second floor.
Panasonic TV + IDA-8 + Tannoy Mercury V1i in living room.
PC + DAC-10 + 2 x STA-9 + Pro-Ject CD-player + Audiovector SR3 AA in my mancave.

KLH007 · « **Reply #53 on:** 23 Apr 2016, 10:01 pm »

Where are you hiding the second STA-9?

KLH007 · « **Reply #54 on:** 23 Apr 2016, 10:02 pm »

Is it black and barely visible?

larsg · « **Reply #55 on:** 23 Apr 2016, 10:04 pm »

Silver for right and black for left

Armaegis · « **Reply #56 on:** 23 Apr 2016, 10:36 pm »

Quote from: larsg on 23 Apr 2016, 09:56 pm

All the switches was set correctly. But as a last try I moved the mono switch up and down many times and finally it "clicked" in place and both STA-9 was at 74/75 Db.
Never gonna touch it again !!

Hey awesome that it worked out. I had a feeling that was the most likely culprit.

John Casler · « **Reply #57 on:** 24 Apr 2016, 12:37 am »

Quote from: larsg on 23 Apr 2016, 10:04 pm

Silver for right and black for left

That's the problem, SILVER is "always" louder than Black. . . .just kidding of course.

Do check that switch and make sure it is tight and secure.

There is a little nut that tightens it up to the chassis. I had one that worked itself slightly loose,

Glad to hear the issue is actually resolved for you.

drumnman2 · « **Reply #58 on:** 25 Apr 2016, 12:15 pm »

Please let us know if you feel going to 2 mono amps improve the sound quality. I have been enjoying an sta 9 for a few months and am considering doing the same.

duke of dorkdom · « **Reply #59 on:** 25 Apr 2016, 01:52 pm »

Quote from: rustydoglim on 20 Apr 2016, 06:53 pm

In short, it doesn't double down is because 1) we are conservative in our spec and 2) the power supply is the limiting factor, nothing to do with the amp. More power = more cost also (amp also has to scale up) = bigger amp = NOT IDA-8 anymore

Okay, that makes sense. Also opens door to future upgrades (external beefier PS) which is cool.

Got another question:
I like how you can "design" your sound switching in different pieces of the 9 and 10 series. If I understand correctly, having both pre/DAC and power amp being 10s is the closest to neutral and using both 9s is the warmest. Where does DAC10 with one STA9, DAC10 with two STA9s, and DAC9 with ST10, all rest on the spectrum?