[xcluded]

Quote:

Originally Posted by _Spanky_ /img/forum/go_quote.gif Thanks sp70 I hope I can be the first to do it and perhaps pave the way! The right channel showed readings under 40mv... I think there might be something wrong with my unit to show over 180mv on the other channel. I sent Ryan a e-mail and we'll see what he says about my unit. I don't recall bearmann getting un-even offset on the channels so I think it's just my unit and if that's the case the LM4562 is safe but don't hold me liable.

bearmann changed his opamps as well ? or he left it as default ?

 

[_Spanky_]

Xcluded, yea he did. I think he tried a similar one to the LM4562. It was a couple pages back...

Anyway, after opening and testing my unit a bit, I've come back with mixed feelings but now I see no problem. I'm thinking it's my multimeter. The last 2 tests I did were with 2 different opamps and I was under 10mv for both of them on both channels. I've almost had this for a week and if there were serious problems, my headphones would have already been melted or fried (both pair that I've used on it). Ryan was very nice and explained some things to me that made sense and combined with my last 2 tests, have put my mind at ease.

I also went over my cardboard mock-up of the HDAM and realized I missed something critical... the thickness of the cardboard. Now I think a person might be able to fit 1 or 2 HDAM's BARELY in the Maverick. I wouldn't count on it though, since you would at least have to wrap them in electrical tape to prevent them from shorting against the case. The 2 locations I'm looking at are between the transformer and the PCB then again around the headphone opamp socket. Sometime I plan to try them out and if it doesn't fit then I'll run the wires through the vent slots into a separate case that I'm already mocking up

 

[xcluded]

Quote:

Originally Posted by _Spanky_ /img/forum/go_quote.gif Xcluded, yea he did. I think he tried a similar one to the LM4562. It was a couple pages back... Anyway, after opening and testing my unit a bit, I've come back with mixed feelings but now I see no problem. I'm thinking it's my multimeter. The last 2 tests I did were with 2 different opamps and I was under 10mv for both of them on both channels. I've almost had this for a week and if there were serious problems, my headphones would have already been melted or fried (both pair that I've used on it). Ryan was very nice and explained some things to me that made sense and combined with my last 2 tests, have put my mind at ease. I also went over my cardboard mock-up of the HDAM and realized I missed something critical... the thickness of the cardboard. Now I think a person might be able to fit 1 or 2 HDAM's BARELY in the Maverick. I wouldn't count on it though, since you would at least have to wrap them in electrical tape to prevent them from shorting against the case. The 2 locations I'm looking at are between the transformer and the PCB then again around the headphone opamp socket. Sometime I plan to try them out and if it doesn't fit then I'll run the wires through the vent slots into a separate case that I'm already mocking up

Thanks spanky once again. It's been ages since i used my multimeter. Hopefully i will get it right when i test it in a few days time.

 

[_Spanky_]

No problem. This is all a learning process for me as well and I want to spread the help/advice/knowledge that I receive.

 

[Legis]

Quote:

Originally Posted by _Spanky_ /img/forum/go_quote.gif Xcluded, yea he did. I think he tried a similar one to the LM4562. It was a couple pages back... Anyway, after opening and testing my unit a bit, I've come back with mixed feelings but now I see no problem. I'm thinking it's my multimeter. The last 2 tests I did were with 2 different opamps and I was under 10mv for both of them on both channels. I've almost had this for a week and if there were serious problems, my headphones would have already been melted or fried (both pair that I've used on it). Ryan was very nice and explained some things to me that made sense and combined with my last 2 tests, have put my mind at ease.

What Ryan said to you? Did you measure under 10mv also with LM4562? What DMM do you use? I sampled five of LM4562s yesterday after I had ordered Mavaudio D1 from Ryan but now I'm not sure if I can use them.

Could the variance rise from high tolerance of capasitors in the output of DAC and op-amps? I thought that if there were capasitors at the output of the DAC an opamp, there would be no DC offset? Can somebody locate these output buffer capasitors to see what's going on with them?

DC offset can also be controlled with resistors: http://www.national.com/an/AN/AN-31.pdf

 

[_Spanky_]

Ryan mentioned that many multimeters don't have good ability to accurately measure millivolts. This seems to be true as mine jumps all over the place with nothing connected. He said that in R&D they use much higher precision tools to make sure everything is operating properly.

He also said that he's had no reports of any unit damaging headphones. He told me that having a 140mv difference between the channels would produce significant higher noise in one channel and I never noticed that.

I don't know what was going on... I'm baffled by it really. Both the LF353 and LM4562 measured actually 11mv or less on either opamp and either channel. In some cases it went down to 1mv.

The fact is that I've been using the LM4562 for over 4 days now with every night burning in using my cheap headset. If something were seriously wrong, I would imagine I would have a broken piece of equipment.

 

[Legis]

Ok, that's good to hear. I don't think there is any design flaw in the D1.

 

[xcluded]

Anyone using special audio type of power cable or using the default cable ?

Any advantages by using the special cable ?

 

[ninjikiran]

Quote:

Originally Posted by xcluded /img/forum/go_quote.gif Anyone using special audio type of power cable or using the default cable ? Any advantages by using the special cable ?

Whacha mean? You mean the power plug for the actual device?

 

[xcluded]

Quote:

Originally Posted by ninjikiran /img/forum/go_quote.gif Whacha mean? You mean the power plug for the actual device?

ya. the power plug cable for the D1.

because when i auditioned this unit back at a shop , they have this interesting power cable.

 

[ninjikiran]

Quote:

Originally Posted by xcluded /img/forum/go_quote.gif ya. the power plug cable for the D1. because when i auditioned this unit back at a shop , they have this interesting power cable.

Ask the grognards and they will tell you absolutely. But in the real world, no. I don't think buying expensive power cables are going to make it any better unless you can hear any interference if its not properly grounded. Ferrite cores seem to be a cheap way to ensure no strange interference. Also keeping it away from noisy devices like computer monitors or devices with magnets like speakers would probably be good practice.

 

[Legis]

I see the power cable question the way that if you use some kind of a power filter it's recommended to use also a shielded power cable after the filter so EMI and RFI can't get into the filtered power between filter and equipmment. Cables thickness should be greater with powerful PA-amplifiers and power amplifiers in general than with preamps and other equipment that needs less power.

In home use 3x1,5mm2 cable is at least adequate. If you are not going to change all the cable that runs inside the walls, you won't get any benefits from using s ultra thick cable at the last 1-1,5 meter of the power line.

Best way to make a good shielded cable is DIY, commercial cables usually cost like they are made of gold.

 

[djnagle]

Quote:

Originally Posted by Legis /img/forum/go_quote.gif IBest way to make a good shielded cable is DIY, commercial cables usually cost like they are made of gold.

Do you have a link to a good DIY thread on this??

 

[Legis]

Quote:

Originally Posted by djnagle /img/forum/go_quote.gif Do you have a link to a good DIY thread on this??

Actually I don't, at least not in a language you would understand

. But all you need is a quality cable and right plugs for each end. The braided shield should be connected to ground connector only at the end that is inserted to the wall socket. This way all the emi and rfi that hits the braid are sucked to the "wall", not to the equipment. Sorry for ot.

 

[Legis]

By the way, has anybody measured the THD%, noise level etc. of the Mavaudio D1 with Rightmark audio analyzer or similar? It is done just by connection the D1 in the middle of the signal path. Soundcards output (A or D) -->Tube Magic --> soundcard's input.

I saw one measurement somewhere in the thread but it was done in 16bit/44,1kHz mode I think. Could somebody test their D1 with digital in (24/48 and 24/96) and also with analog in.

I will measure mine when it arrives, I have E-mu 0404 PCI soundcard. The only problem with this particular e-mu is that recording does not work properly in the Win 7 all the time.