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TOPIC: DDRC-88A: 8 channel analogue input/output Dirac

DDRC-88A: 8 channel analogue input/output Dirac 4 years 5 months ago #18508

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guofong wrote:
stephenting99 wrote:
(3) Digital volume control. Assuming the source signal is has 24bit of data, there would be no loss of that data if the volume is at 100%. I.e. input = output. As the volume is turned down from maximum, it will start to truncate from 32bits until eventually reaching 24bits. Question is how far down the volume can one go down from 32bits to 24bits? Is it 10%? Or 20%?

I have the same question.Will some information be lost when I turn down the volume by DDRCA-88A?

I am thinking of using DDRC-88A to control the volume of my system. No preamp as following:
OPPO 103D(analogue output) --- DDRC-88A --- poweramp

Is anyone doing this? Does it sound ok without an AV preamp?

Dear Both,

Because this topic will most likely easily open a can of worms (i.e. not exactly related to DDRC-88A and Dirac Live), I propose to link this topic to the following very good app note from our friends at ESS Tech: www.esstech.com/PDF/digital-vs-analog-volume-control.pdf
On miniDSP products, we do master volume control at the DAC (i..e internal path) which indeed leads to very good performance.

Bottom line, you'll have some headroom for the master volume control and it shouldn't be a worry (i.e. most likely you'll have an issue before hand in one of the devices ahead of the DDRC-88A). For individual channels (i.e. OUTPUTS level page), we're doing digital volume control on the 32bit Sharc path but these are minor adjustments so you will be fine. Bad rap of volume control come from the CD player (16bit days) I think.. Our 2cts.

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DDRC-88A: 8 channel analogue input/output Dirac 4 years 3 weeks ago #20656

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I am running the DDRC-88A with MiniDSP Balanced 2x4 in a box crossovers... I am getting a lot of background hiss. I am thinking it is the gain settings between the 2,. What should my gain settings be for the DDRC-88A when it is feeding the balanced 2x4, and what should it be in the 2x4? I believe I have the 2x4 set for the 2v balanced and the DDRC-88 set to 8v for the input and output. Is this correct or should they be in different settings? I am using consumer balanced equipment except for my subs.

Equipment list and path
Oppo 103 out via 7.1 analog outputs > 7.1 analog inputs on a Krell Showcase 7.1 preamp... output via balanced XLRs to DDRC-88A ..Phoenix balanced inputs/ Phoenix balanced outputs > MiniDSP 2x4 balanced (In a box)inputs / outputs via balanced > Lexicon 5.1 amp (horns) / Sherbourne 5/1500 amp (bass bins) (both amps are fully balanced with XLRs). The hiss is very noticeable from my MLP.
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DDRC-88A: 8 channel analogue input/output Dirac 4 years 3 weeks ago #20668

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@ Ellisr63,

The issue might be down to gain structure mismatch. You're using 8Vrms into a miniDSP 2x4 balanced that can only do 4Vrms (see user manual for more details) so it could very well also be a raised THD due to saturation (simple check of RMS meters in plug-in would help).

Knowing it's a very efficient horn, you don't need that kind of level (i.e. you've got a mismatch most likely of a poor SNR, i.e.running the horns very close to noise floor of the system because, by default efficient horns don't need much output). Does this make sense?

I'd try to switch your outputs to using unbalanced for your horns. You'll find that it's much better level matching I'd say.. Else you'd need to "pad" the signal.
Even out of a miniDSP 2x4 balanced, the output level is more for ProAV amps (i.e Crown/Peavey.. ) Not exactly the type of levels you'd want for consumer gear.

hoping this info helps
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DDRC-88A: 8 channel analogue input/output Dirac 4 years 3 weeks ago #20684

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devteam wrote:
@ Ellisr63,

The issue might be down to gain structure mismatch. You're using 8Vrms into a miniDSP 2x4 balanced that can only do 4Vrms (see user manual for more details) so it could very well also be a raised THD due to saturation (simple check of RMS meters in plug-in would help).

Knowing it's a very efficient horn, you don't need that kind of level (i.e. you've got a mismatch most likely of a poor SNR, i.e.running the horns very close to noise floor of the system because, by default efficient horns don't need much output). Does this make sense?

Should i switch to the lower jumpers on the Dirac too (switch them from the on position)?

I'd try to switch your outputs to using unbalanced for your horns. You'll find that it's much better level matching I'd say.. Else you'd need to "pad" the signal.
Even out of a miniDSP 2x4 balanced, the output level is more for ProAV amps (i.e Crown/Peavey.. ) Not exactly the type of levels you'd want for consumer gear.

hoping this info helps

Thanks, I was running Yamaha Pro amps prior to getting the Dirac. I really don't want to convert to unbalanced to the power amps if at all possible. I ordered some XLR attenuators to see if they will solve the problem. The current setup hiss is the only issue with the 2x4s. Once I get the noise floor I am assuming the line between burst will become a thin line instead of like a crayon?
Last Edit: 4 years 3 weeks ago by ellisr63.
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DDRC-88A: 8 channel analogue input/output Dirac 4 years 2 weeks ago #20693

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It would have been real nice if a crossover could have been included in the DDRC to avoid using the 2x4s... I would have bought a 2nd DDRC-88A.
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DDRC-88A: 8 channel analogue input/output Dirac 3 years 10 months ago #21265

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devteam wrote:
keith2014 wrote:
Can someone please give me a definitive and straightforward answer to this:

I am using as Denon X5200W AVR and Emotiva amplifiers.

How do I set the jumpers on the 88A and how do I set the dipswitches?

The analog rated output for the Denon is 1.2V and the rated input for the Emo amps is 1.1V.

Thanks.

Sure, we can help. Based on your ratings, using an unbalanced setup (RCA in/out) that is configured for 2Vrms would be the best setup.
Both your source (Denon) and your amplifier are within that rating.

When trying to match a piece of analog audio gear inside a setup, you just want to make sure that:
- Max output level of your device upstream (i.e. Denon) is close enough to the max input capability of the device (i.e. DDRC-88A @ 2Vrms max in on RCA)
- Max input level of your device downstream (Emo amp) is not going to get overloaded easily.

Because you have almost a unity gain setup here (1.2V in = 1.1V rated power), you'll be good with default unit with default jumpers.
If you feel you need higher outputs, you can easily modify the internal jumpers. Just talk to us when this happens and what the symptoms are.

DevTeam

Hi

I have a 88A in order so I am wondering a similar question, since I`m not fully understand the output/input sensibility maybe I can get some help answering if I am within the default settings when adding a DDRC-88A between the pre/pro/amp example below.

> Marantz 8801 Rated output over rca 1.2 V

> Cary 7.125W> Input Sensitivity1.0 Volts

So the real question is will the default setting in the 88A work? Thanks!
Last Edit: 3 years 10 months ago by Johnny.
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DDRC-88A: 8 channel analogue input/output Dirac 3 years 10 months ago #21273

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I am wondering if this setup will work. I don't have a separate pre/pro and amp, I use an AVR. However, I do have an Oppo which is leveraged as a DAC. Currently I use it to send 2 channel music from the HTPC to the Oppo and then analog in to the NAD receiver. So I'm thinking I can send 2 channel from HTPC over USB and 5.1 from HTPC to Oppo with optical. Analog from Oppo to DDRC-88A and from 88A to NAD receiver. Any reason this wouldn't work?
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DDRC-88A: 8 channel analogue input/output Dirac 3 years 10 months ago #21304

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@ Johnny,

Sorry for the late reply. In answer to your question, all your settings are "consumer AV" levels (i.e. no high level requirements such a Pro AV). You're all good with a unit shipped with default jumpers/DIP switch settings.

Keep us updated if you have any questions.

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DDRC-88A: 8 channel analogue input/output Dirac 3 years 10 months ago #21579

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BornToMe,

Your proposed setup will work. Please note the following limitations on your setup.

(a) The Oppo bass management issues that needs some firmware updates to resolve. There is a risk of clipping the LFE (sub) channel when more than one of the main channels is switched from LARGE to SMALL (i.e. crossover implementation) and some bass frequencies are diverted to the LFE(sub) channel. If you can do the bass management up-stream of the Oppo, i.e. in your HTPC, it would be better.

(b) The NAD receiver will need to be in DIRECT/PURE DIRECT mode to remove any DSP processing and simply amplify the low level analogue signals from the Oppo to your speakers with volume control.
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DDRC-88A: 8 channel analogue input/output Dirac 3 years 10 months ago #21684

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I have question on the input gain of the DDRC88A and the suitability of using it with my pre-amp.

I use the Onkyo SC-PR5508 AV controller RCA out to the DDRC.

The tech specs are attached in the png file.

It seems to be rated as

Rated RCA Output Level and Impedance
1 V/470 Ω (PRE OUT)
Maximum RCA Output Level and Impedance
5.5 V/470 Ω (PRE OUT)

The DDRC seems to be rated at 2V input voltage which is lower than the max output stated in the manual in the onkyo. Will this mean that the input will be clipped?
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DDRC-88A: 8 channel analogue input/output Dirac 3 years 9 months ago #21746

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@ venkatesh

These "max output" are rated so I wouldn't worry too much about there (i.e. what's the likelyhood that you're going to put your AVR @ 100%? You'll most likely damage something else before that.. ;-)
Put the unit in 2V in, 2V out and you should be fine.

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