### Advertised specs for STA-6 and STA-9

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#### fracs

• Newbie
• Posts: 2
##### Advertised specs for STA-6 and STA-9
« on: 9 Mar 2018, 12:03 pm »
Hi all.

Ref.
STA-9:  http://www.nuprimeaudio.com/product/sta-9/?v=3e8d115eb4b3
STA-6:  http://www.nuprimeaudio.com/product/sta-6/?v=3e8d115eb4b3

I'd like to confirm the advertised "gain" values for the STA-6 and STA-9. On the NuPrime website, for example, the STA-9 is quoted with a gain of "x 22". However, they also quote input sensitivity as "232.8 mV rms for 1 W output into 8 Ohms". So to try and reconcile this data I use the following reasoning:

1. NuPrime quote input sensitivity for STA-9 as 232.8 mV rms for 1 W output into 8 Ohms.

2. Using P = V^2 / R, then output voltage is 2.828 V rms.

3. Therefore, voltage gain is 2.828 / 0.2328 = 12.15

4. Convert voltage gain to power gain on logarithmic scale:  20 x log10 ( 12.15 ) = 21.69 dB

5. NuPrime quote that STA-9 gain is “x 22”. Given the above calculation, I think they meant to say “22 dB”.

If my reasoning is correct then does this mean that the gain of the STA-6 is similarly 28 dB and not "x 28" ?

Thanking you all.

#### rustydoglim

##### Re: Advertised specs for STA-6 and STA-9
« Reply #1 on: 16 Mar 2018, 06:15 pm »
I think Jye (by the way, he is our senior product manager for audio) has replied to you in email, I will ask him to post here.

#### Jye

• Newbie
• Posts: 2
##### Re: Advertised specs for STA-6 and STA-9
« Reply #2 on: 19 Mar 2018, 07:34 am »
The gain specs for the amplifiers are in multiplication factor and not in dB. The website is correctly stating a 'x22' gain for STA-9 and a 'x28' gain for STA-6.

#### fracs

• Newbie
• Posts: 2
##### Re: Advertised specs for STA-6 and STA-9
« Reply #3 on: 19 Mar 2018, 02:24 pm »
Yes, thank you. Jye replied to my email. Jye confirmed that the specified gains are linear.

I was interested because I am doing a "paper exercise" to compare expected behaviour of the NuPrime STA-6 with my former amp, a Yamaha AX-570. The Yamaha amp has a (power) gain of 29 dB, and this worked well with my Roland Digital Piano + JBL speaker combination. I recently sold the Yamaha amp, and have been looking for a suitable replacement. The JBL speakers are ancient, but I still like them.

I have since had another look at my math and I have realised a curious oddity: 28x linear (voltage) gain is approximately equal to 29 dB (power) gain. Ie. the "numbers" work out to be "about the same".

Therefore, I have decided to order the NuPrime STA-6. Destination is Canada.

#### left channel

• Jr. Member
• Posts: 38
##### Re: Advertised specs for STA-6 and STA-9
« Reply #4 on: 19 Mar 2018, 03:19 pm »
Gain aside, those two amps have very different sound signatures. The six is cold and the nine is warm.