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Little Dot I+ Tube Rolling - Page 150

post #2236 of 2242
Quote:
Originally Posted by gibosi View Post

Quote:
1. Do people really not plug and unplug headphones while the unit is on?  That seems like a real pain!  I'm pretty much just ignoring that.  I just make sure that the volume is all the way down when I plug and unplug.  Has anyone ever actually run into any issues by doing this?

Since the 1+ has an SS output stage, it isn't really necessary to plug and unplug the headphones.

That said, if you think that you might eventually get an all-tube amp, this is an excellent habit to develop. If tubes are going to arc and short-out, it typically happens the instant power is turned on and/or off. And since the amp's power tubes are connected directly to your headphones, very bad things can and do happen. And further, to save wear and tear on the amp's headphone jack, I have a 2-ft headphone extention cable always plugged into the amp, and then connect and disconnect the headphones from the extension cable. But again, it isn't necessary with the 1+, but still, it is a good idea.

Oh, but see, this is what I normally always do. Power things up with volume all the way down. Plug in headphones, listen, volume down, unplug, power down. Of course, i don't bother with this with the iPhone, but with Duet or my Korg and any other audio gear. Don't want power up or down transients on my headphones!


BUT, this is the opposite of what the LD users manual says and the opposite of what other posts in this thread have claimed. Connect enerything, then power up the LD. I don't like this. Plus, if you want to switch headphones, it's a royal pain. Apparently it is not only not necessary but is bad advice to boot.
post #2237 of 2242

I haven't been here in awhile.  I have been using the Little Dot I+ with Voskhod 6J1P tubes and 2107 op amp with a pair of Q701s.  The combination still sounds awesome but I stumbled across this thread again and now I am thinking about trying a new set of tubes.   

 

Any current recommendations to try with the Q701s?  I mainly listen to rock music: Led Zepplin, Pink Floyd, NIN, Bod Dylan, etc.  

 

I don't have any complaints about my current setup.  In fact it still amazes me how great it sounds.  I figured I would post here to see if anyone can recommend a set of tubes that might sound even better than the Voskhods.  

post #2238 of 2242

My setup is OP 2107 and C3g i love it for my Q701(my end game) another setup i consider is Yugoslavian 6HM5(Plug and play) or 6SN7(the 6SN7 need adapters) and Chatham 6AS7G(this 6AS7G setup need adapter and External Power Supply).

post #2239 of 2242

Thanks for the response i luvmusic 2!  I really appreciate it.

 

BTW, what is a C3g?

 

Any other tube recommendations for the Q701's?  

post #2240 of 2242

just another update after listening to the yugos for a few days now, they're extremely satisfying when listening to anything with bass that's supposed to slam. IAMX sounds fantastic. I do miss the soundstage on the 408a's for more indie/acoustic stuff though. 

post #2241 of 2242
Quote:
Originally Posted by gibosi View Post
 
 

The C3g and the more conventional tubes used in the LD are all pentodes. That is, they have two more grids than a triode and these extra grids are essential when being used in radio frequency circuits. However, when used in audio circuits, these two extra grids are superfluous at best and detrimental at worst and thus need to be nullified. Since we cannot open up the glass bottle and remove these extra grids, we electrically tie them to either the plate or/and cathode. And thus we convert a pentode into a triode. This process is often called "strapping", and the result is called a "triode-strapped pentode." Unfortunately, in almost all cases, strapping results in more distortion and a frequency response significantly less linear than when used as a pentode.

 

The C3g is unique in that it was actually designed to be used as either a pentode or a triode. Even though the distortion increases and linearity decreases slightly when converted to a triode, it still measures very comparable to quality double triodes of the era, such as the 6SN7, when strapped.

 

Thus a pair of C3gs, converted into triodes and installed into the LD, provide an SQ comparable to the best audio double triodes - think 6SN7, 6DJ8, 12AX7 and so forth. No other pentode can match it.

 

That said, "best" is in the mind of the listener and some in this forum still prefer a pair of Voskhods. The only way to know for sure if these are for you is to try a pair.

 

Cheers

 

 

Quote:
Originally Posted by beekermartin View Post
 

Thanks for the response i luvmusic 2!  I really appreciate it.

 

BTW, what is a C3g?

 

Any other tube recommendations for the Q701's?  

^^^^^^Please read gibosi's Post^^^^^^

Tubes i used to Roll for the Q701>>>Any 12AU7,Chatham 6AS7G,Tung-Sol,Sylvania 6SN7 but since i have the C3g i don't use those anymore.

post #2242 of 2242
So, in case anyone is interested, I measured the output impedance of the LD I+, and it is so low it is difficult to measure! Which is really great!

I put a 440Hz sine wave into the inputs via my iphone and a signal gen app. I had the volume maxed, but forgot to remove my volume limit which I had set. I put the LD volume knob at about 3/4 and got:

208.5 mV open circuit.

Then I put a 50.3 ohm resistor in as load and got 208.0 mV.

If you do the circuit analysis, you get . . .

0.12 ohms

However assuming the worst case scenario, error-wise, and we round the open circuit voltage up a tenth of a mV and the loaded voltafe down a tenth, we still get .17 ohms.

So, definitely less than .2 ohms, which is outstanding.
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