Gain structure setup

[patate91]

I'm planning to switch my passive system to active. I need help to figure out how I'll configure it.

Here's the plan

Sources :
CD player ans Raspberry pi 3B

Crossover, preamp and DAC :
Minidsp 2x4 HD

Amplifiers:
For Tweeter : Emotiva A-100
50w @ 8 Ohms, 0,6V = 20 VRms Gain : 30,45 db.

For woofer : Emotiva A-300
150w @ 8 Ohms, 1,2V = 34,64 VRms Gain : 29,20 DB.

So 1,25 db difference.

Speakers :
Horn loaded compression driver : TAD TD-4002, sensitivity : 110db/w
Woofer : TAD TL-1603, sensitivity : 97db/W

So there's a 13 db difference.

Is it correct to say that the tweeter (horn) needs a 14,25 db (13db from divers sensitivity + 1,25db from amplifier's gain) attenuation.

If yes what's preferable :

1- Use the Emotiva A-100 volume pot to attenuate (I'll try to get the information from Emotiva to know how the volume pot works) + small adjustment with the minidsp output gain control. (I guess the A-100 volume pot needs to be set at max then turn down)

2- Do all the attenuation from the minidsp output gain control.

Master volume control done with minidsp's master volume control.

 

[Daverz]

You could also use inline attenuators, though I suspect digital attenuation will be fine.

https://www.parts-express.com/harrison-labs-12-db-rca-line-level-audio-attenuator-pair--266-244

 

[PaulD]

I would try digital level adjustment first, as it is essentially a no-cost option (only requires config). Assuming the level control is properly implemented in DSP, then it will also not affect the quality at all.

There may be other factors, such as interference on a line etc, in which case you might perhaps want to maximise the analogue level as much as possible and attenuate it as late as possible in the chain. But I'd try the digital option first.

 

[March Audio]

I'm planning to switch my passive system to active. I need help to figure out how I'll configure it.

Here's the plan

Sources :
CD player ans Raspberry pi 3B

Crossover, preamp and DAC :
Minidsp 2x4 HD

Amplifiers:
For Tweeter : Emotiva A-100
50w @ 8 Ohms, 0,6V = 20 VRms Gain : 30,45 db.

For woofer : Emotiva A-300
150w @ 8 Ohms, 1,2V = 34,64 VRms Gain : 29,20 DB.

So 1,25 db difference.

Speakers :
Horn loaded compression driver : TAD TD-4002, sensitivity : 110db/w
Woofer : TAD TL-1603, sensitivity : 97db/W

So there's a 13 db difference.

Is it correct to say that the tweeter (horn) needs a 14,25 db (13db from divers sensitivity + 1,25db from amplifier's gain) attenuation.

If yes what's preferable :

1- Use the Emotiva A-100 volume pot to attenuate (I'll try to get the information from Emotiva to know how the volume pot works) + small adjustment with the minidsp output gain control. (I guess the A-100 volume pot needs to be set at max then turn down)

2- Do all the attenuation from the minidsp output gain control.

Master volume control done with minidsp's master volume control.

With 110dB sensitivity you are going to struggle to rid yourself of amp/dac hiss.

From experience I know the Minidsp isnt the quietest DAC around. If analogue in nature the Emotiva volume will probably provide adequate noise attenuation.

 

[etc6849]

I rewired my speakers and went full active over a year ago. It was the best decision I've ever made.

My speakers are very sensitive too. I didn't try the MiniDSP 4x10, but had an Ashley speaker crossover I sold due to hiss. I also sold my Emotiva amps due to hiss and ended up with Benchmark AHB2's driven by a Xilica XD4080 (FIR filters and low noise floor).

I drive the Xilica XD4080 using AES (digital signal) from an RME soundcard as this resulted in the lowest possible noise floor from my setup.

 

[patate91]

I received my Emotiva A-100 today. I still don't have the minidsp and the A-300 amplifier.

I did some test with my cd player as a source, no preamp.

CD player is : 2,3 Vrms, noise : 98db "cd player setting", and "? db usb setting".

Raspberry pi 3 b on or off -> usb cd player's DAC. Volume at maximum there's a small amount of hiss, bearly audible at listening space.

"CD setting", volume at maximum there's almost no hiss. I need to have my ear at the horn's mouth to ear it.

CD player off, volume at max = dead quiet.

Since I used my speaker's crossover, the compression drivers are already pad down to match the woofers sensitivity.

Minidsp 2x4 HD has a 102 db noise floor, it looks like it should be good for a no hiss setup.

 

[patate91]

My cd player/DAC, looks like the DAC chip is CS4398.

http://audio.teac.com/product/cd-2000/specifications/

 

[patate91]

About the volume pot, the guys at Emotiva confirmed me that everything is is analogue.

I'll have to attenuate with an SPL Meter.

 

[patate91]

I finally setup everything.

I'm lowering gain with the A-100.

Minidsp's DAC hiss can be heard at listening spot on compression drivers. While music is playing I can't hear it.

It looks like I'll have to check for a SHD to get ris of hiss. Amir said SINAD is around 90db for 2x4 HD and 111db for HSD, I think it would be enough