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Little Dot I+, Grado SR125i, and tube rolling questions

post #1 of 8
12/13/10 at 4:23pm
Thread Starter 

Hi all! Long time lurker, first time poster.

 

After reading many reviews a few months back I purchased the Grado SR-125i's, as an upgrade for my Senn HD280s. For my budget, they're fantastic. I've used a BioScienceGeek cmoy for years with my Senns, but they were customized for 64Ω and 150Ω. This means I need more gain in order to power the 32Ω Grados.

 

Upon research it seems Little Dot amps are a great budget-minded foray into tubes. People seem to recommend the I+ (hybrid) for use with Grados because it can pound out more power to low-impedance cans.

 

Before ordering one this afternoon I looked around to find out what people thought of the tube options. The basic Chinese 6JI doesn't seem very highly regarded, and the other two options are a bit over priced (save for the convenience factor). After looking around I found that the Mullard M8100/6AK5 seems to be liked by a lot of people. I found some NOS, "military version," of them on eBay (item # 270629165066). Are these counterfeit? They're being sold from Taiwan. If not, anyone have any experience with these, versus the retail versions? 23USD for a pair seems fair, compared to some tubes out there. Thoughts?

 

Another question goes towards changing the opamp. Is everyone pretty happy with the included MC33078 or does it get swapped out often for other chips?

 

I'm pretty excited to start using tubes for the first time. The amp should arrive in a few weeks.

 

Thanks!

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post #2 of 8
12/13/10 at 4:37pm

I really liked the stock 6JI tubes, but had one fail. Little Dot gave me a song and dance about having to clean the tube pins etc, but one clearly failed (major hum; glow was distinctly different from the good tube). It wasn't worth the hassle to pursue it, so I tried a bunch of cheap 6AK5 family tubes (1980s RCA; vintage Philco - quite microphonic; vintage Western Electric - pretty good) and finally settled on a GE 5654 from 1985 for both the SR125i and Denon AH-D2000. I think they sound great. I wouldn't pay a premium for 'matched' tubes. I buy cheap lots of 5-10 tubes, pick two at random and have never had a pair out of balance (or noticeably different) from any other pair. I won't pay more than a few dollars/tube.

 

I use the stock opamp and don't see any reason to switch.


Edited by nycbone - 12/13/10 at 4:38pm
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post #3 of 8
12/13/10 at 4:56pm
Quote:
Originally Posted by DittoBox View Post

...

I've used a BioScienceGeek cmoy for years with my Senns, but they were customized for 64Ω and 150Ω. This means I need more gain in order to power the 32Ω Grados.

 

Upon research it seems Little Dot amps are a great budget-minded foray into tubes. People seem to recommend the I+ (hybrid) for use with Grados because it can pound out more power to low-impedance cans.

...


I believe you'd need less gain for the lower impedance HP's like the Grados, but like you said they draw more current. Someone please correct me if I'm wrong. So the CMoy should work fine with your grados. Of course high-end amps are going to sound better. I'd like to hear what people have to say on the matter!

popcorn.gif

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post #4 of 8
12/13/10 at 7:08pm
Thread Starter 
Quote:
Originally Posted by nycbone View Post

I really liked the stock 6JI tubes, but had one fail. Little Dot gave me a song and dance about having to clean the tube pins etc, but one clearly failed (major hum; glow was distinctly different from the good tube). It wasn't worth the hassle to pursue it, so I tried a bunch of cheap 6AK5 family tubes (1980s RCA; vintage Philco - quite microphonic; vintage Western Electric - pretty good) and finally settled on a GE 5654 from 1985 for both the SR125i and Denon AH-D2000. I think they sound great. I wouldn't pay a premium for 'matched' tubes. I buy cheap lots of 5-10 tubes, pick two at random and have never had a pair out of balance (or noticeably different) from any other pair. I won't pay more than a few dollars/tube.

 

I use the stock opamp and don't see any reason to switch.


These aren't matched, I don't think, they're just a pair. I'll try the stock to begin with and maybe find a couple of others to see how they sound. Microphonic meaning that it is affected by vibrations more so than other types of tubes? Thanks!

 

Quote:
Originally Posted by T.B.N. View Post

 

I believe you'd need less gain for the lower impedance HP's like the Grados, but like you said they draw more current. Someone please correct me if I'm wrong. So the CMoy should work fine with your grados. Of course high-end amps are going to sound better. I'd like to hear what people have to say on the matter!

popcorn.gif


You might be right. I know that I do have to turn up the volume pot on the amp quite a bit more than I did with my Senns, to get the same level. I've noticed that when I've plugged the Grados into my Mackie 4-channel mixer that seems like it has better bass extension and a slightly wider soundstage. It's rated for 60Ω, though I'm not sure of wattage.

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post #5 of 8
12/13/10 at 7:54pm

I vastly prefer a 2107 opamp over the original.  Not sure about those Taiwan Mullards.  Keep checking ebay for some UK sellers..  they're pretty reasonable. 

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post #6 of 8
12/14/10 at 12:21am

Grado SR325i through a Little Dot 1+ with stock opamps and matched Sylvania NOS GB-408A tubes. Sounds fantastic. Takes away all the brightness that folks complain about with the 325's (I know you are talking about the 125) and leaves a very warm and lush mid and high range that just....I don't know...it's fantastic. I had my LD1+ on a Citypulse DAC last week with these headphones and it was heavenly. As far as how well the LD1+ powers these things...with my 770/80's I have to turn the volume up to 50-60 for a decent listening volume. With the Grados...anything over 20 is too loud. I'm at 15 right now and it is just right.


Edited by ArmAndHammer - 12/14/10 at 12:23am
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post #7 of 8
12/14/10 at 3:12am

Vibrations, including sound vibrations. If you gently tap a tube with a finger nail, tap the amp case (probably a better idea) or remove the headphone plug (which I usually don't do while the amp is turned on), you'll hear it. I can snap my fingers without touching the amp near the Philcos and hear it in the headphones. Kind of cool, but I couldn't use them.

 

There are a lot of eBay (and other) seller with dime-a-dozen tubes with asking prices that are too high IMO. Some even advertise that they are (as if specifically) for the LIttle Dot, when they are just generic radio tubes. You can get excellent tubes for just a few $. Additionally, vintage doesn't necessarily mean better. The best sounding tubes that I've found were made within the last 25 years.

 

This is just based on my experience. I haven't tried other families of tubes. YMMV.
 

Quote:
Originally Posted by DittoBox View Post

These aren't matched, I don't think, they're just a pair. I'll try the stock to begin with and maybe find a couple of others to see how they sound. Microphonic meaning that it is affected by vibrations more so than other types of tubes? Thanks!


Edited by nycbone - 12/14/10 at 3:16am
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post #8 of 8
12/14/10 at 2:29pm
Thread Starter 

I just picked up an OPA2107 for 4USD from a local supplier. I'll try that one as well as the OPA2227 from my current amp. I also found lot of 5 of those GE 5654 for about 10USD. I thought about grabbing a pair of OPA627s and a browndog adapter, but those 627s seem overpriced compared to some of the other opamps out there. I assume due to the hype.

 

Well, I've got the bug. :)

 

Thanks for the input everyone!


Edited by DittoBox - 12/14/10 at 2:35pm
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