Phono-1 MkII - AudioCircle Limited Edition

Audiovista · « **Reply #40 on:** 19 Mar 2013, 01:30 am »

JackD's preamp is on it's way!

tomytoons · « **Reply #41 on:** 25 Mar 2013, 12:59 pm »

Audiovista · « **Reply #42 on:** 26 Mar 2013, 12:15 am »

Somebody is having fun! Way to go Den

JackD · « **Reply #43 on:** 26 Mar 2013, 12:33 am »

tomytoons

Got my order in today from Mouser so I now have plenty of options with it and what Boris included. Been thinking about trying a LOMC for the first time and the two you are dealing with are at the top of the list. Would be interested in hearing your opinions on the two of them. Going to start my experiments with loading tomorrow. For now I have just left the unit like it was delivered at 40db, 47Kohm and 50pf. Sounds fine with both the Grado Z1+/8MZ and the Denon DL-110 but I am sure fine tuning will make it better. Like others have said this thing sounds way above it's price range and is a steal.

Jack

tomytoons · « **Reply #44 on:** 27 Mar 2013, 01:33 pm »

tomytoons · « **Reply #45 on:** 12 Apr 2013, 01:06 pm »

JackD · « **Reply #46 on:** 12 Apr 2013, 01:46 pm »

For my unit 50pf is the default. Boris's standard default is 150pf.

tomytoons · « **Reply #47 on:** 12 Apr 2013, 04:16 pm »

tomytoons · « **Reply #48 on:** 17 Apr 2013, 06:03 pm »

neobop · « **Reply #49 on:** 17 Apr 2013, 08:06 pm »

Quote from: tomytoons on 12 Apr 2013, 01:06 pm

I will post this since I'm a dum di dum dum and may help others as far as anything on this loading stuff.
Through the generous help of JackD this site will calculate any given resistance values you may need.
Very useful. Hey, I'm a dip switch person.

http://www.electronics2000.co.uk/calc/series-parallel-resistor-calculator.php

Use the Resistors in Parallel calculator.

Thanks Jack for all the answers and time to my questions.

Is 50pf the default Capacitance?

I didn't realize the plug in load resistors are in parallel with 47K. That means that 47K can not be exceeded, you can only load down. There are a few carts that do much better at loads greater than 47K. The Shure M97 comes to mind, many people prefer 62 to 70K. A nice solution to this would be to order 1 Mohm as the default. Then any plug in resistor would have it's value as the load.

Most modern MM carts want to see < 200 or 300pF total capacitance. Maybe if you order a 50pF default, another cap could be added to the load resistor if needed? Arm wire + cables are usually 75 to 150pF. Sometimes 300pF or so is used for LOMC. There are a few LOMC that have a lot of inductance for their output and can cause ultrasonic ringing or oscillation in some preamps with extended bandwidth. This can cause intermodulation distortion. Maybe 300pF would prevent that? Not sure about that, but I think those caps are for noise.

BTW, many carts that are perceived too bright like the AT-440, are often run at 32K. That's 47K in parallel with 100K. Any lower and it's too dull on most preamps.
neo

tomytoons · « **Reply #50 on:** 17 Apr 2013, 08:28 pm »

Audiovista · « **Reply #51 on:** 18 Apr 2013, 01:51 am »

Thanks for sharing your experiences guys!

Changing default input resistors and capacitors would not be a problem. I can install pretty much any value. There would be no charge for that.

neobop · « **Reply #52 on:** 18 Apr 2013, 11:03 am »

Quote from: tomytoons on 17 Apr 2013, 06:03 pm

Just how much better are these?
$$$$$
http://www.partsconnexion.com/resistors_vishay_var.html

In an ultimate sense they're better, but I don't think they make much sense in this application. I can hear a slight difference in my AHT where there are no other resistors in parallel, but sometimes I use the same Dale resistors and they sound just fine. The advantage for me is mainly in temperature stability with some of the more expensive resistors, because there is no auto DC offset circuit and it drifts with temperature. Setting the DC offset is a PIA and takes some time. That's one of the reasons I plan on getting the Vista. It's plug n play in comparison and I think I already know how it sounds - fast, clean, and neutral. I want to hear what's on the record, not some romanticised version of what's there. I have some other phono stages built into preamps or integrated amps, but I doubt if they come close to Vista.
neo

I almost forgot, you can call Mouser or Digikey on the phone to order resistors. If you know the brand(s), values and tolerance you want, it's a lot easier. I know Mouser has IRC R55 .1% metal film, and Dale PTF series .1% Ultra High Stability. Can't go wrong with either of these and you don't have to match em. Whoever helps you on the phone can see in an instant if they're in stock etc.

tomytoons · « **Reply #53 on:** 18 Apr 2013, 11:45 am »

neobop · « **Reply #54 on:** 18 Apr 2013, 01:29 pm »

Quote from: tomytoons on 18 Apr 2013, 11:45 am

Are some of the ultra expensive Phono Pre's using resistors like those?
I bet not.
If you are building your own boards as Nick77 is, I would think about it. It is a dual mono design with a Gary Dodd custom power supply. He has got it done maybe he will share his experience with it in the vinyl section. I sure would like to hear it.

I do not think it necessary going that high $ in the Vista.
It is "fast, clean, and neutral" I'm going to leave well enough alone.
I have a mass amount of choices here now.

Still, you think what if..........

I think a couple of them are using nude Vishays. Some high end units have sealed modules so you can't see what's inside. This is done mostly to keep other companies from stealing the design, really. A patent that's worth anything costs big bucks and other companies will steal it anyway and fight it in court yrs later. The consumer electronics industry is ruthless in that respect, as is most big business. So an ounce of prevention... I think this started with Mitch Cotter in the '70s. He used to seal all his electronics in what looked like expanding foam. I had a Cotter SUT that had little silver jumpers in the side of the unit. You could resolder the little jumpers to configure it for different gain and impedance. It had captive silver cables coming out, and the inside was completely sealed.

The AHT Non Signature phono stage was the only 5 star component in TAS for something like 3 yrs running in the late '90s. The TOTL sold direct for around $5K, not really expensive by today's standards, but if it went through dealers it would have been close to $10K. You could see where the money went though, it had teflon boards with silver traces. A couple of caps on each channel were teflon and the plug in resistors for load and gain were the encapsulated Vishay they used in the space shuttle. The regular version of the IC, 3 per ch, cost $30 ea today, but the military version was used, at least for the one handling the signal. The power supply had a hugh toroidal transformer which could power a pretty big amp. My AHT isn't the TOTL, but I have the teflon boards and caps and a big power supply with regular Vishay 102, I think they are. Those are the ones I substitute sometimes. When the AHT designer got out of the audio biz, he had offers from Herron and Walker to buy the design. He sold it to Walker and it now has a DC offset circuit and sells for $14K.

I have no idea what Nick77 is building, and I don't really know how much difference a nude Vishay or a space shuttle resistor would make. They are super stable in all kinds of temp, if the music puts you in space.

My suggestion would be to save the money and get more records.
neo

tomytoons · « **Reply #55 on:** 18 Apr 2013, 01:46 pm »

tomytoons · « **Reply #56 on:** 27 Apr 2013, 08:32 pm »

topround · « **Reply #57 on:** 27 Apr 2013, 09:01 pm »

I had the oc9 for some time and I thoroughly enjoyed it. Very musical, gives a taste of what great MC's can do for a fraction of the price. Play with different stepups it will be fun with that cart.

cheap-Jack · « **Reply #58 on:** 27 Apr 2013, 09:23 pm »

Hi.

Quote from: neobop on 17 Apr 2013, 08:06 pm

.
.. There are a few carts that do much better at loads greater than 47K. The Shure M97 comes to mind, many people prefer 62 to 70K. A nice solution to this would be to order 1 Mohm as the default. Then any plug in resistor would have it's value as the load.

"Much better" at what? Higher than 47K load will sound better or what?

With my DIY tube phonostage, I used a 100KR trimmer as my MM cartridge load. I found trimming up & down across 47KR mean value, the entire frequency response lever is somewhat lifted towards LF or HF.
In my case, I found setting it to 52KR, the bass is somewhat boosted up a couple dBs & is fairly noticeable.

c-J

neobop · « **Reply #59 on:** 29 Apr 2013, 02:31 pm »

Quote from: cheap-Jack on 27 Apr 2013, 09:23 pm

Hi.
"Much better" at what? Higher than 47K load will sound better or what?

With my DIY tube phonostage, I used a 100KR trimmer as my MM cartridge load. I found trimming up & down across 47KR mean value, the entire frequency response lever is somewhat lifted towards LF or HF.
In my case, I found setting it to 52KR, the bass is somewhat boosted up a couple dBs & is fairly noticeable.
c-J

Loading is relevent only for a specific cartridge. In general, a dull or rolled off cart will sound flatter using a higher resistance value and the opposite is true for an overly bright cart.

http://www.tnt-audio.com/sorgenti/load_the_magnets_e.html

Many people load the M97 at 62K while others load the AT-440MLa at 32K. To a large extent it depends on the sound of your system, and taste.
neo