Maverick Audio DAC/Amp - Page 56

I don't know if anyone is interested but I was reading up on some stuff Uncle Erik (frequent poster here) had to say about power and whatnot. He highly recommends Isolation Transformers before fancy power cords. I started looking around and came across an eBay seller that has some for dirt cheap. I picked up a 2-pack, he sent me 3 and it works great with the Maverick. I don't know if it has done anything to the sound quality since I haven't had time to listen but typically, the Isolation Transformers reduce EMI/RFI noise, eliminate ground loops and something else I can't remember right now. These also have nice plugs/cables on them and have 2 fuses to keep your equipment safe. If you want to try it out, it's a cheap investment:
eBay Seller: emesurplus: isolation, Business Industrial items on eBay.com

They are rated for 100VA which from what I understand would be around 100 Watts. I asked Ryan and the Maverick uses about 20 Watts so nothing to worry about there.

I'll post back if I notice any huge sound changes... I kind of doubt it but who knows.

A few updates

I just wanted to chime in with a few updates about my D1.

First, I reported that there was a really loud hum in my headphone jack. Well, this is only true part of the time. I heard the very noticeable hum when I was using my low impedance noise-canceling headphones. When I turned off the noise-canceling, I noticed the hum almost completely disappeared. Turn NC back on, hum comes back. So, it appears there is some feedback loop with the NC that causes the hum. Just to test my hypothesis, I tried my ultra-low impedance in-ear-canal phones (used for iPod), and I could barely hear any trace of hum. If I paused the music and cranked the volume, I could hear a faint hum. At normal listening volume, the hum is gone.

Lesson learned: NC headphones may not play nice. Or, at least my NC don't play nice.

Second, I started to develop the same problem another member here developed. When I used the direct bypass button, the left channel dropped out and was very intermittent with a lot of static. After opening a ticket with Ryan, he literally emailed me back in minutes and suggested I push the button a few dozen times. This seemed to have fixed the problem. I did that, and the clipping stopped. It did come back once more, but a few more pushes fixed the problem. Hopefully, it never comes back.

Lesson learned: The direct bypass button might need to be "worn in." Perhaps there's a rough piece of metal, a burr, or a a shaving that gets in the way of completing the circuit. Just wear it in a little to restore a solid circuit. It seems to have fixed the problem for now. If it comes back again, Ryan told me is still behind the product. I am fairly confident it's a mechanical switch problem and nothing to do with the pcb or amps.

Yea Noise Cancellation headphones are already amplified so it won't work as well.

At the same time you can try connecting the NC Headphones to the RCA L/R that way you skip the headphone amplification altogether.

On another but similar note @ the JVC SU-H1 or w/e it was called. As I said with mines since it is amplified the results were not good. I got a nice hum and disconnected it after a few seconds. I don't want to overload the circuit if that is even possible. I am really looking forward to hearing the results of it now since it is unamp'ed which I might actually look into.

I kind of consider that to be a bit of snake oil for audio, unless you are having actual power problems like EMI or whatever have you. BUT having 2 fuses in place is a definite plus since it protects your equipment.

I asked about the possibility of using the tube-out for plugging headphones into and someone said that it's "hot" output and could damage headphones. I don't know how it would react with Noise Canceling headphones or if the SS out is any better. Just a warning though.

I can confirm the tube pre-amp out is hot. Somewhere in this thread I noted just how much the pre-amp was running hot--something like 8-14 db higher compared to a normal line-level. It clips straight out as it enters my power amp. I use the signal leveler on my amp to control the signal.

Hooking the NC phones to the RCA jacks was a good idea, but I doubt I'll ever do it. I bought the D1 mainly as a tube pre-amp for my stereo, but I like the option of using cans sometimes. When I go to the cans, I'll just turn off NC or use the in-canal cans and not worry about hum at all.

Hmm i think i may have screwed up my opamp order... or maybe not. I ordered this from browndog along with a standoff adapter. This will work for the mav fronts right? I shouldve probably asked before ordering but ....

muad, that looks fine. I just don't see how it is orientated, I don't see a half-moon or anything.

Hmm i wouldnt know... ive never installed an opamp before! When I get it Ill take some pics and get ryans input. Hopefully it works out. Thanks again for a speedy reply

edit: well actually i just noticed that it has a square pin mark on the topside of the pcb... so should be pretty straightforward.

I would get confirmation before taking my word but I think that the square represents the side that typically has a half-moon design:

Not the tube out I meant the other output next to the tube. Its a standard RCA output. Regardless I have a pair of noise cancelling headphones as well and they don't work at all with NC on or off w/ amplification. I never use them anymore but the white noise is kind of relaxing once in a while.

Isolation transformers and filters are not snake oil.
They only play a part if you have a very high audiophile setup.
If you don't believe that, and prefer to believe 'science', these isolation transformers are used in labs for example.
But if you don't hear the difference between 44,1kHz and 48kHz, between volumes in foobar, windows media player or kmixer, don't bother.

I try yo improve my setup bit per bit in order to educate myself, in order to learn and discover new sensations etc...
If you just resume everything at what you can hear without reflecting on how do you hear, what do you want to hear/perceive, then don't spend too much.
But if you go the audiophile path, and it is long path where you co evolve with your setup, then, go cleaning your energy, this is the first step, because it will allow you to hear any improvements in the other rest of the setup (like audio cables).

About the volume, there is a difference between volume implementation in software. Now, software evolves quickly, but the basics are, if you use soft volume on 16 bit it will reduce quality (from a certain low level), if you use soft volume on 24bit it will have very much less effect. Now there is something called dithering which consists to put 16 bit sound into 24bit sound, work with volume level and then put 24bit sound into 16bit sound.
For example, in old itunes version, they didn't do dithering, so the volume in itunes reduced quality and it was audible by a lot of people (remenber, strong effect at very low level), after few versions, itunes used dithering and quality was restored.
There are some reviews saying very bad things about the quality of KMixer in XP, now things seem to have changed in vista or seven.

Same goes for upsampling. Now some piece of software are really good in upsampling. It beats really pro systems from 10-20 years ago. Don't forget that software has this capability to evolve very quickly. This potential stops when you reach the DA part, after that everything is analogique and it is another domain. I will not care about bit perfect usb since i use the maverick, but i am waiting for 24 bit support in order to upsample everything on the computer (anyway at the end everything is upsampled to 24bit/96k in the maverick).I you want bit perfect dont go maverick, go NOS dac. There is no interest to stay 16bit/44.1k on a computer, keep you cd player and buy a good NOS dac or better buy a very good cd player, there are plenty.

Based on that, I prefer to use the analogique volume from the maverick or from my integrated amp.

Just a bit of CR to end this 'heavy' post
My wife told me she can now understand some lyrics with the maverick she couldn't hear before when using the cd player. I riped it in lossless format, put it on my ipod, and use the denon ASD-51 dock to take the digital out of the ipod into the maverick !

Sorry for my english, and thanks to have read this 'heavy' post !

Don't forget that you can use a trim circuit to remove offset when replacing opamp, which allows you to remove any caps placed after. Caps on audio signals are bad, remove them, it will be clearer ! (apart from the tube out, tubes make caps necessary, but remove any caps from the solid state out).

And to finish that, a bit about topology, the dac is a chip which convert digital to analog, then you have an I/V converter, which converts current into voltage (not sure the dac in the mav needs that, perhaps it is embedded, normal dacs need this part), then your audio signal is sent to the headphone amp with its own opamp and in parallel sent to the pre out. The headphone amp and the preamp are two circuits in parallel and independent.
The pre out is composed of two stages, the first one is solid state out with one opamp, and a second stage which is the tube stage. You have one output directly from the first stage (opamp) which is a pure solid state output and you have a second output from the second stage which is the tube output. This last output is a mixed solid state and tube output.
If you change the opamp in the first stage, you also change the quality of the tube stage. If you change the tube you only change the tube out and nothing else (nor the headphone amp, nor the solid state output).
So at least, first change the opamp of the preamp with a LM4962, it is very good, it is also cheap, so buy two and change the headphone one ! Then, change that lamp !

Some sound cards can be used for bit-perfect playback through Spdif, don't need to use the usb. I already had one that was capable though.

I did not bother to switch the direct button anymore as I just fix the volume at 3 o'clock. (same level of output as when direct is engaged).

My only issue is the "cringing" sound that comes with the bass lines when using USB on songs such as hypnotized by ani d'franco, spanish harlem by rebecca pidgeon and heartbeat in on of pink floyd's song on DSOTM album, can remember the title. This is not evident when using SPDIF. Apart from those, I'm happy with my MAV.

I advise to use the volume at 12 o'clock because the bypass level (3 o'clock) is too hot.

well for me 3 o'clock is the equivalent level as when the direct button is engaged. and as per ryan's advise also. thanls anyway.

as regards to the "cringing" sound, guess what? after I changed my player from Winamp pro to foobar2000, the annoying sound disappeared!