[kb1014]

Hi there!

Long time no post here but... after reading for a "while" about Little Dot I+ I've just received my Little Dot I+ and want to share with all of you about opamp rolling. I have some experience in this area and for me and my Grados best SQ is from Analog Devices family of AD8599, AD8066 and AD8022. I highly recommend one of them (for me best works the AD8599 with WE408A tubes). Enjoy!

PS: Really great little amp

 

[Trapper32]

Quote:

Originally Posted by Aynjell /img/forum/go_quote.gif Yeah, but mine doesn't sound right with teh LM4562, and using the goo stuff isn't on the top of my list of things I want to do to my amp. I'm okay with soldering a cap to the op amp. If I could get that damned thing to work right, I probably WOULD go for LM4562. It sounds good, but doesn't work in my setup. If there was a more forgiving op-amp with the same sound signature, I'd buy it, but right now I don't trust putting something that has static in one channel in my amp.

Have you tried more than one 4562?? They are very sensitive to static electricity, etc. and I was just wondering if perhaps the individual opamp might be faulty???

 

[Aynjell]

Quote:

Originally Posted by Trapper32 /img/forum/go_quote.gif Have you tried more than one 4562?? They are very sensitive to static electricity, etc. and I was just wondering if perhaps the individual opamp might be faulty???

I talked t pat, s next time I order I'll probably order 4-5 of them. If none of them are good, I'll give up on it, but if I can get just one good one I'll be happy.

 

[Trapper32]

Quote:

Originally Posted by Aynjell /img/forum/go_quote.gif I talked t pat, s next time I order I'll probably order 4-5 of them. If none of them are good, I'll give up on it, but if I can get just one good one I'll be happy.

Let us know how it turns out when you get some more.

 

[PatOMalley]

There was a set of single opamps, the AD825, which was close to the LM4562 but with a little more bass oomph up into the lower mids.

Reference Audio Mods Has them but the only issue is will it fit between the caps?

 

[Aynjell]

Quote:

Originally Posted by PatOMalley /img/forum/go_quote.gif There was a set of single opamps, the AD825, which was close to the LM4562 but with a little more bass oomph up into the lower mids. Reference Audio Mods Has them but the only issue is will it fit between the caps?

That's a single channel op amp. right? You'd need the dual version, wouldn't you?

 

[Aynjell]

Ah, looks like we'd need this:

AD825 Module Type 2, Dual AD825, 8 Pin/DIL, 11/16"L x 5/8"W x 9/16"H: Reference Audio Mods

 

[PatOMalley]

It's a single but there are two on that board. One on top and one under.

 

[Aynjell]

Quote:

Originally Posted by PatOMalley /img/forum/go_quote.gif It's a single but there are two on that board. One on top and one under.

I didn't realize.

The documentation does say 1 AD825 on your example, and 2 AD825 on the example I linked. I doubt there are two, to be honest. How do you know?

 

[PatOMalley]

no, your right. I linked the wrong one.
anyway, that is a worthy opamp set.
The 4562 is far more transparent and open, sort of like there is no opamp there. the color that the AD has is not a negative to me and I like it just fine. I really wanted to try one but I am not sure if it will for between the caps and didn't want to risk the $40 to find out.

Dang. I suppose just asking the seller what the dimensions of the board is would fix that worry.

 

[Aynjell]

Quote:

Originally Posted by PatOMalley /img/forum/go_quote.gif no, your right. I linked the wrong one. anyway, that is a worthy opamp set. The 4562 is far more transparent and open, sort of like there is no opamp there. the color that the AD has is not a negative to me and I like it just fine. I really wanted to try one but I am not sure if it will for between the caps and didn't want to risk the $40 to find out. Dang. I suppose just asking the seller what the dimensions of the board is would fix that worry.

If you find out, let me know. I may try one down the road.

Next month is when I'm going to put another order in for op-amps. Content figuring out these EF91's. They've been the most graceful tubes to burn in. I put them in and they sounded good from day one. And the glow is pleasing.

 

[oblivious]

hi all, looking at potentially getting this amp very very soon, and was wondering if any once has experience 6AK5 Pentode tubes on this amp? and how they found them. Cheers!

 

[Aynjell]

Quote:

Originally Posted by oblivious /img/forum/go_quote.gif hi all, looking at potentially getting this amp very very soon, and was wondering if any once has experience 6AK5 Pentode tubes on this amp? and how they found them. Cheers!

Not sure how you might find them, but it does appear to be supported (using the 6JI jumper settings).

Past that, I know nothing. O

 

[Rotomoto]

Quote:

Originally Posted by oblivious /img/forum/go_quote.gif hi all, looking at potentially getting this amp very very soon, and was wondering if any once has experience 6AK5 Pentode tubes on this amp? and how they found them. Cheers!

I've got a matched set of Valve Electonics 6ak5 tubes, and I'm not very impressed. Compared to the stock tubes, the highs are recessed and they lack detail. I suppose they might match well with a bright set of cans, but I'm putting them back in their boxes.

 

[Brian_the_King]

Quote:

Originally Posted by morfic /img/forum/go_quote.gif Well, i just measured the DC Offset of the LT1364 in the I+ And it is at 28mV, almost 1.5x what Tangent recommends as a safe value to ensure you do not cook your phones. So for anyone interested in using this opamp, it's not a suitable choice in the I+ w/o changing the circuitry to compensate for the increased DC offset. For anyone interested in opamp rolling, stick to FET based opamps or check that the bipolar transistor's "Input Bias Current" is in the nA or less range (LME49720/LM4562 are this low and thus they work, FET based opamps are in pA range) The uA input bias current which is more typical for bipolar opamps can cause a large enough DC Offset to be worrysome. Data sheets are easily available via google, easy to double check this before using any bipolar opamps. LM4562/LME49720 are a notable exception, 1mV of DC offset is nothing to worry about.

Quote:

Originally Posted by Aynjell /img/forum/go_quote.gif ...I am sure only two of these might be decent but from what I'm seeing only the LT1364 is a real serious upgrade for this amp, aside from the LM4562...

Quote:

Originally Posted by Rotomoto /img/forum/go_quote.gif Ok, I just loaded in my new LT1364 opamp (per aynjell's suggestion) in my I+. First of all, after I ordered it, I did a little digging through this thread and noticed that some people had some high DC offset measurements with this opamp, which concerned me. As soon as I installed it, I let it settle in for 10 mins or so and measured my offset at the headphone ouputs. It was 18mv plus or minus .5mv in each channel. A tad high, but certainly safe enough for me. So far, I only have a few hours of burn time on it. It sounds more forward than the stock opamp. The highs are more prominent, borderline edgy-bright. I'm hoping this will settle after some burn-in. The low end has filled in nicely and seems well controlled. What I'm really seeking is that tubey, liquid sound. Is this possible with this amp? My amp still has the stock tubes. Gain is at 3db. I'm going to do some listening for the next week or so with this setup to get used to it, but would definitely like to start rolling some tubes shortly.

I could go on quoting posts from this thread, but I think this is enough to quantify my confusion. Does anyone else care to comment? Is the LT1364 really unsuitable for use in the LDI+? It seems to me that a fair number of people have deployed an LT1364 in their LDI+'s with positive results... I know very little about op-amp rolling or op-amps themselves so I would appreciate any explanation that can be offered.