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Message started by mperdue63 on 01/15/19 at 17:50:21

Title: ZMA inputs
Post by mperdue63 on 01/15/19 at 17:50:21

Input Connections
"The ZMA comes standard with single-ended RCA input jacks rated at 2 volts for
maximum power. Transformer balanced XLR inputs are optional and located
directly next to the RCA input jacks on either side. If your amp was built with these
you can use either balanced XLR inputs or RCA inputs but not both at the same
time."

Does this mean don't connect both at the same time or simply don't play both at the same time? I was planning to connect my Roon setup using the XLR and my turntable using RCA, but not play them at the same time.

Thanks for the help!


Title: Re: ZMA inputs
Post by Archie on 01/15/19 at 18:11:41

I think you can have them both connected but only one can play at a given time.  You'll need some kind of switch up stream.

Title: Re: ZMA inputs
Post by mperdue63 on 01/15/19 at 18:17:05

Thank you

Title: Re: ZMA inputs
Post by Delta 77 on 12/05/19 at 13:52:08

Hi mperdue63,

I was thinking of doing the same, bypassing the preamp..
using the XLR for the DAC and RCA for the turntable..
Just not turning them on at the same time..

Did this setup work..??


Title: Re: ZMA inputs
Post by mperdue63 on 12/05/19 at 16:18:14

Works fine, I've not experienced any problems connecting both.

Title: Re: ZMA inputs
Post by Delta 77 on 12/05/19 at 23:52:16

Thanks,

Title: Re: ZMA inputs
Post by Archie on 12/06/19 at 01:00:17

I wonder why Steve didn't (couldn't?) put a switch on the amp?

Title: Re: ZMA inputs
Post by Bhamm on 11/23/21 at 15:28:55

Hello all.  I realize this is a 2 year old thread, but it relates to my issue.

I recently received my ZMA after a 10 month wait.  One of the upgrades was the XLR input.  I connect my DAC to the XLR and a turntable to the RCA input.  When I play the DAC I only get half or less volume.  Turned all the way up, the volume is no where near loud.  When I play the TT, I get full volume.  This is with both sources connected.  I decided to disconnect the TT and now it plays full volume through the XLR input.

I’ve contacted Decware but still waiting for a response (yes I know there busy).  Has anyone else experienced this same thing, or should I be concerned.  It seems very unique that I would have to physically disconnect the RCA input, even when not playing, for the other input to play at a normal level.

I eventually want to use a preamp connected to the XLR and run all sources through it, but I’m not there yet.  

Bhamm

Title: Re: ZMA inputs
Post by Archie on 11/23/21 at 16:46:19

The ZMA has ONLY one input regardless of how many "inputs" are on the amp.  This question came up in the original development thread.  You can't cheat this by having both RCA and XLR inputs on the back.  My XLR places are plugged on mine so this question doesn't come up.  I guess you found out that you can have only one device plugged in (or turned on?) at a time.

If the TT has to be unplugged and not simply off (phono stage off), then I agree that is a major inconvenience.

Title: Re: ZMA inputs
Post by Bhamm on 11/23/21 at 18:26:59

Archie,

I missed the info regarding how the inputs function.  And I thought I had read all posts about the ZMA in the last 10 months.  

Once I have a preamp, it will be a non-issue.

Thanks,

Bhamm

Title: Re: ZMA inputs
Post by Archie on 11/23/21 at 19:52:43

The single input was a disappointment and pushed a lot of us into switch boxes and preamps.  Fortunately the CSP3 (in my case) is a big enhancement.  Do you have to unplug one of the inputs or just have the second source off?

Title: Re: ZMA inputs
Post by Bhamm on 11/23/21 at 21:35:35

Yes, in my case I’m using a manly Chinook phono preamp. It’s tube-based so does not lend itself to being turned on and off frequently.  So when using the balanced input I unplug the RCA input, otherwise no volume.  Strangely though if I go the other way, I don’t need to unplug the XLR input and still get full volume from the RCA side.

I’m guessing there was no selector input-switch used in this case because it would degrade the signal in someway.  The preamp I’m looking at has a remote which is very high on my requirement needs.

Title: Re: ZMA inputs
Post by Bhamm on 06/27/22 at 18:07:48

As a follow up I received my preamp and have it working wonderfully.  It’s a Supratek Chardonnay (all tube) pre with 5 inputs and a remote.  It’s connected to the ZMA via XLR cables.  Now switching between inputs is done by the input selector on the pre.  The preamp has definitely added weight to the music with no perceivable downside.  And, as a bonus the preamp chassis looks very similar to the ZMA’s angled chassis.  A stellar match!

Title: Re: ZMA inputs
Post by Carlsbad on 07/04/22 at 05:09:00

As of tonight, my ZMA has a selector switch.  works and sounds great.  I have my good DAC loaned out but with my backup DAC, it is sounding great.  

Tonight I switched to movie mode for the first time since I got the ZMA wihout having to swap cables.  Works and sounds great.  

While I was in there I replaced all the signal cables with Mundorf Angelique (silver, gold, copper) wire.  I also replaced the RCA connectors with  KLEI low mass connectors.

Here is a photo of the switch and the new connector. The switch is just in front of the output transformer, one per side.  Looks great.
https://share.icloud.com/photos/0813QSD5UrSOREOOdhgtmSFkg

Title: Re: ZMA inputs
Post by Bhamm on 07/08/22 at 02:31:05

Great work.  Had I not decided to use a Preamp, I would be looking at your fix too.

Title: Re: ZMA inputs
Post by Carlsbad on 12/15/22 at 04:48:18

Here is a photo of one of the 2 tiny switches in front of the output transformers.  I put it closer to the transformer than the tube because the tube is warm.  


Title: Re: ZMA inputs
Post by 4krow on 12/15/22 at 17:07:18

I agree that the switch is needed. Even if one source is off at the input, it sounds like it may well have an effect (negatively) as well. Likely because the impedance of the device(s) connected 'don't get long together'.
I had a somewhat related problem with a class D power amp that I built with only one input, but the designer made some kind of error at the input. The quick answer in this case was to add an output buffer in the input line. Not really an option here though.

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