MiniDSP - Page 43

Well, My unbalanced mini's rca completely broke off after about 3 times of a cable being attached. urgh! I've boxed them both up and sending them back tomorrow. On the bright side, I found another mic2200 for $40 locally and hooked it up (guy only lived 5 block away!), works great, easily drives the ep to clipping. The 2242H's are impressive with the Noesis for sure!

Did anyone else notice the turn off thump doesn't seem to come out of the Balanced MiniDSP if you're using it via RCA (unbalanced)?

I'm guessing the + and - side of the balanced output don't taper off evenly when power is yanked which causes the output spike. I'll need to bring it back into work and connect it up to the oscope to confirm.

I use my balanced with RCA's and experienced the thump on the first day. Been on ever since.

The MiniDsp LCR usage sound quality concerns I had made in post #1233 seem to be pretty much unfounded -- did a bunch of reading last night and it appears this thing has been pretty well vetted over the course of many A/B listening tests. The build quality concerns that I keep reading about persist though.

I still plan on waiting a while as they further refine the product and options (e.g., get the build issues sorted out, work on the voltage issue, attend to the thump issue, offer XLR instead of Phoenix, etc.).

One doesn't always have that choice. Sometimes the power just goes out. In my case, I tallied up the replacement cost of the drive-units to be hooked up to my miniDSP (Pioneer EX/TAD and Aurasound), stopped when the number was north of $6500 because my eyes were wide open at that point, and decided to keep mine not only on, but also connected to a UPS. Comparatively cheap insurance.

No, but I'll test it when I test the rem in/out function.

Most of the "problems" people report with the minIDSP are simply gain structure issues. Which also means, as Stereodude pointed out - and thanks for the measurements, BTW! - that they don't and sometimes won't play well with some upstream gear.

With how common a digital out connections on receivers are nowadays, I wonder if using that would bypass many of these gain issues? And remove several D/A conversions. My Pioneer SC-25 has a digital out and I'm going to try that instead of the unbalanced out on my new minidsp (although with my DCX2496 it was actually unbalanced out from the reciever but balanced in on the DCX2496 using an adaptor, how would that change the gain issues?)

How will you control volume? And, it still needs a DAC.

I'm not sure if the receiver applies volume to the digital out or not. What is the norm, just a passthrough basically? There will of course be a final D/A conversion but still you can get rid of an additional A/D and D/A if you keep it all digital until the output of the minidsp. If the digital out is just a passthrough then the idea won't work obviously.

For all channels, or just the left/right?

It's just a pass through, so no volume control.

Just stereo. The manual is pretty vague, the one example is using the digital out to hook to a CD/R or DAT component. So it is probably just pass through as lukeamdman says. So this brings me back to my other idea: currently I use the unbalanced out of the receiver to the balanced input on the DCX using an adaptor. Pros/cons versus using unbalanced on both ends? Is the shield pin on the adaptor just a dummy pin?

If you make one end unbalanced, then the whole cable is unbalanced. So, other than the physical properties of the connectors, there is no difference.



Nope:

I understand it would be unbalanced if one end is, what I'm wondering is it would still offer more flexibility with the minidsp wrt to input voltages?

You are asking a question that may seem straightforward and simple to you, but I'm unsure of what it is you are asking.
The balanced board has the greater I/O voltage tolerance when it is connected in an unbalanced configuration. IOW, using the .9V jumper setting, the balanced board, connected with unbalanced cabling, can accept 1.8V (edit: and output 2V). The 2V jumper position doubles the input to 4V (edit: while the output remains 2V), when connected with unbalanced cabling.
Using balanced cabling, the board's I/O voltages are as rated.
These voltages may be higher, as Stereodude's results have shown.

You might find this helpful:

MiniDSP FAQ
Edited by Oliver Deplace - 12/26/12 at 1:57pm

Ok, so after setting back and reading the last 4 pages, I am thoroughly confused. Is the ballanced version still the best one to get, even if your receiver doesn't have any ballanced in's or out's? I have a Denon AVR-3312 that I have connected to an EP4000 with a bump box, (thanks wranger!) in between. I am about to order a 2 new subs and will most likely be ordering the MiniDsp to EQ them.

Does the QSC DSP-30 work better for EQ'ing both LCR's and subs?

How do I measure the voltage out of my receiver?

What advantages does the ballanced version have over the non-ballanced version?

Probably, yes. It doesn't have any disadvantages that I can think of other than the Phoenix connectors.
For the mains, maybe. For the subs, maybe not. It all depends what you want to do and the specific issues you encounter.
Plug in a RCA cable to the pre-amp output you want to measure and hold the red lead from the multimeter on the center tip and the black lead on the outer ring while a test tone is playing. Make sure the meter is set to measure AC voltage.
Higher output voltages (if you use the balanced output to an XLR input on the amp)

Stereodude, thanks to Oliver Deplace minidsp faq link I looked it over and noticed this:



It appears that if you wire the balanced minidsp with an unbalanced connection that it'll accept up to twice the voltage. In all of your tests did you try this configurationi out?



Also, the faq states:

Has anybody noticed any issue with this possible delay?

All my testing consisted of feeding the MiniDSP an unbalanced signal. I didn't try feeding it a balanced input signal (though I do have a true balanced DAC I could have used).

I don't agree with some of the data in the table though. It doesn't match my findings. The outputs when used in a balanced configuration ( - and S not shorted) have 2x the AC voltage output as it does when wired for unbalanced ( - and S shorted). Ie: If you feed it 4Vrms unbalanced it will output 4Vrms balanced or 2Vrms unbalanced (assuming you've got it set for straight pass through).

I didn't test the .9Vrms setting, but I'd just expect the input to clip at a lower voltage.
Edited by Stereodude - 12/26/12 at 5:37pm

So help me understand this, if I have unbalanced coming in and balanced going out, what should I expect?

Bump, that is what I am trying to figure out as well.

From Stereodude's post, I gather that you'll get a 4V balanced output from a 4V unbalanced input.
Since that output voltage is twice what is specified and runs counter to the mfr's. documentation, I'll apply the obligatory - YMMV.

the documentation linked by audiophile leads one to believe that you go from a 4 V in to a 2 V out....is that why I have to turn it up so much louder?

In the balanced 2x4 product brief, it specifies maximum output as "2Vrms (5.6Vpp) from + to ground, i.e. 14dBu in balanced mode". So they spec it in a weird way, from one output leg to ground, rather than differentially between the two output legs, which would give you twice the voltage (4 Volts RMS). As a further check, you can compute dBu as follows:

dBu = 20 * log10(VRMS / sqrt(0.6))

Solving for VRMS, you get:

VRMS = sqrt(0.6) * 10^(dBu / 20)

Setting dBu = 14 per the spec above, you get:

VRMS = 3.88 Volts

That's a slight discrepancy: 4 VRMS is really 14.26 dBu.

Bottom line: If you take the output single-ended, you lose 6 dB.

For what it's worth, I just switched from a Bash plate amp to an iNuke. I use an Onkyo TX-SR805. Unbalanced pre-out to balanced in on 2x4 - unbalanced out to the BASH. I can't remember why, but I was using the 2 volt input jumper setting with the BASH. Gain on sub amp about 3/4 of the way up. Sub would calibrate somewhere a little below 0 on the Onkyo. After zeroing out the settings on the MiniDSP, going unbalanced out from the Onkyo to the MiniDSP, BALANCED from the Mini to the Behringer, the sub would calibrate with the iNuke gain at or very near full tilt, and the Onkyo's sub level set between +10 to +14.

Switching the jumper to the .9 volt, I am back at about the same. After crude lunchtime adjustments, the Behringer is a little about 3/4 of the way up, and the level in the Onkyo is around zero. I guess this was all evidence of low output voltage from the Onkyo, and high input sensitivity of the iNuke.
Edited by baniels - 12/27/12 at 5:06am

Yes, if you run unbalanced in (S & - shorted) and unbalanced out (S & - shorted) it will effectively cut your voltage in half (~6dB loss). Unbalanced in (S & - shorted) and balanced out (S & - not shorted / using S, +, & -) the voltage output equals the input voltage. Both of these statements assume the input jumpers are on the 2.0V setting.

The output voltage will approximately equal the input voltage if the jumpers are on the 2.0V setting.

Ok so let me get this straight, if I go un-ballanced out of my Denon AVR-3312's subwoofer pre-out, into the Minidsp's un-ballanced input, then from the Minidsp's ballanced output to my Behringers ballanced input, I can expect to have 4volts coming out of the Minidsp? (assuming the 2volt jumpers are used)

. Would it make sence to use an RCA to XLR cable going from my AVR-3312's subwoofer pre-out into the Minidsp's ballanced input? Would that gain any advantages over using unbalanced from the AVR-3312's subwoofer pre-out to the the minidsp?

The RCA to XLR cable I used was still only two wires. I'm picking up some XLR to XLR cables to use on the output side and sticking with what I have on the input side.

I have the unbalanced version.

You could have up to ~4.6V coming out of the MiniDSP (if you also have ~4.6V coming out of your Denon).
Using a RCA to XLR doesn't gain anything over connecting the RCA cable directly to the phoenix connector.