Little Dot I+ Tube Rolling - Page 30

Yea, bout 10 days. From what I know, its on its way, and will arrive this week, hopefully.

Oh, only 10 days? Felt like it was longer, must have been those 3 days w/o AC that made it feel like weeks
Enjoy, i don't think you have phones you won't enjoy on it.

Well, I better start this post with a confession; ive been tube rolling for the first time of my 40y+ life!
I let the stock ones go, and put my Russian EF95 go to work!
Fun!

There has been some question about the K601 paired with the LD1+, and from my first 6hrs of experience, Ide say that they match pretty good. There is in my mind enough drive and power out of the stock LD1+, and it sound bloody amazing!
This evening, ive put my A900 to work (tv in the same room), and after the first roll, im amazed! Love these cans.
Listening to a new LP with Van Morrison, Tupelo Honey, and it is fantastic!
Love life!
Cheeers

LD I+ tube differences

tube differences are behind the opamp on the LDI+; the opamp is last in the signal chain. I go back and forth between the OPA2228[schmooze] and the LM4562[clarity].

There is no going back for me, i am hard core into LME49720/LM4562. Which is also the opamp in the cmoy with active ground i just built.
I got a chance to hear LT1364 and OPA2107, since both came with my I+, nope, not much fun, and one would require proper design of my cmoy to not kill my phones with too high a DC offset voltage, actually want to go measure DC offset with those two in the I+ too, the other (2107) oscillates like mad in cmoy.
I may sell the MkII to fund a DAC purchase, since the I+ drives both my D1001 and my HD600 so very well.
The MkII's tubier sound and pre-out is what still has me wonder about which amp to sell and which to keep.
LME49720 while being a bipolar (aka difficult) behaves so great in cmoy, it tells a lot about opamps

been looking around but can't find any other mods to the i+.
have you changed output caps, resistors, etc?

Time permitting i would first test components in my cmoy amp (cmoy with active ground).

Mostly curious about input cap material changes and how easy it is to hear the differences, on a simple amp like this i should be able to pick up on it eventually. Just been to busy to actually play much with cmoy (other than using it) since i built it.
And i must say as happy as i am with it and as much as it reminds me of my LD MkV i used to have (yes also got a LME49720 transplant), i am not in too much of a hurry to play with the cmoy's parts.

So my next goal maybe changing the cmoy amp enough to accept the LM6172 and running it stable w/o too much DC offset. (LT1364 in a cmoy delivers a whopping 300mV of DC offset o_O, OPA2107 oscillates in a cmoy, and MC33078P give 100mV of DC offset)
Considering the MC33078P is the default choice for Little Dot, i actually feel much better about opamp swapping in LD amps.....

I May still go and measure DC offset in I+ tonight.

If i ever make an interesting mod to the I+ or have an interesting find, i'll post it here.
Will be interesting to see how the LM6172 performs in the I+ once i have a LM6172 for the cmoy (DigiKey was out of stock when i ordered parts for cmoy :/)

I have a National LM4562NA. Is this the one you speak of for the Little Dot I+?

yes

That's the one.

^Nice. I will try it. Also plan to make some RMAA measurements. Once I do it if anyone's interested I can share them here as well.

http://www.danielgoller.com/rmaa/

I would love to have something to compare this to.

Yeap, those kind of measurements were the ones I was going to do. Also in one of the tests, when changing the power stage from 220V to 110V, was he actually testing the LD I+ with a wall converter, or was it from a 220V wall socket? Because the use of 220V has a THD% of 1.6%

I will also perform some measurements of the new Cute Beyond (need to buy some darn cables...). Even so the LD I+ and LD MKII measure very good. (APArt from inconveniences of tubes, that is getting extremely hot, needing to turn off the unit if you want to change headphones, waiting for the tubes to warm up not as SS instant charge )

Definitely like SS more than tube or Hybrid.

I bought the I+ used, somehow the seller ended up with one where input side of transformer was wired for 220V AC, so all my voltages inside amp were 1/2 running here on 110V AC in the US (yes seller was in US too o_O).

The distortion is from tubes running too cold, heater voltage was way low, even my lovely glowing EF91 tubes only mastered a slight glow on the very to of the plates, instead of the full all over glow i knew from the MkII.

Blew my mind when i noticed the 220V sticker on amp. so i rewired it for 110V AC and am enjoying it ever since.

Pat: in an application note for the LME49720 i noticed they bypass it with 1uF caps.
and i measured the LME49720 with 0.1uF bypass caps in the cmoy and the RMAA measurement was a pretty rollercoaster in the highs, since the adding the 1uF Tantalums to the .1uF metal film it is pretty well behaved, might consider adding a 1uF to the .1uF.

When you use bipolar opamps like LT1364, have you ever measured the DC offset?
In the cmoy i got a whopping 300mV, after adjusting resitors (the gain setting pair) i got it down to 100mV (I don't have any 470kOhm resistors to tweak the offset to more sane levels)

Since i don't know how the I+ is really designed, i would measure my DC Offset with anything but FET opamps or the LME49720/LM4562 (FETs have a input bias current in the pA range and LME49720 is the only well behaved bipolar opamps i saw in nA range, bipolar opamps like the LT1364 or LM6172 with input bias current in the uA range need a circuit designed for such high offsets)
Considering the MC33078P of the I+ creates about 90mV offset in the cmoy, the LT1364 might have a potential of creating DC offsets in excess of 20mV (which is like the "under this its safe" threshold)
Having said that, with the LM49720 in the I+ i measured 1mV DC offset only (~15mV in the cmoy)

Two things to think about i guess.

where, why, how

I got the idea for what I am doing from a number of sources, this one being foremost: Working with Cranky Op-Amps

I did not measure anything. I just listened to what the effect was/is.

With the single .1uF cap with it's leads on pin 4 and 8 it was a good improvement. More power or oomph, really a level of stronger focus. But adding the two caps individually on 4 and 8 then tied to ground was a pretty incredible. The level of presence rose appreciably.

So I never thought to measure. If I like what I hear them I'm good. I only get as technical as I need to get my way through.