[john57]

You just take the bottom two screws from the front and back and the bottom half of the case will come off. It might be better if you had the tubes out just to avoid breaking the tubes when you put the Little Dot upside down.
 
 
http://www.littledot.net/forum/viewtopic.php?f=9&t=819&sid=c5ce444cfc5bbeb03dfb4e49d18544ff 
 
Look at the last picture and it will show the op-amp right in the middle of the picture and you pry the op-amp out of the socket and caryfuly line up the new op-amp with the mark or notch on the new op-amp in the same direction of the old op-amp and push in carefully without folding the pins of the new op-amp  undertheath itself. It is common mistake for someone at the first time bend the pins out of position. Good Luck!
 
 

 

[cruizin caleb]

My opamp is on the way, i'll be sure to refer back to your instructions when it arrives. My flat pads just arrived and wow, they really do warm things up. Its interesting how some music sounds better with the flats, and some sounds better with the bowls. Its nice how easy they are to swap back and forth.
 
Quote:

You might want to check out the Amperex 6AK5W for a tube with a strong low end.  They were not easy for me to find, but they are still out there.  A nice combo with the 2107 for good bass and a warm sound.
 

That what I've read. I didn't see them on ebay, is there another place they can be found? I have these ( http://cgi.ebay.com/EF91-SPECIAL-CV5377-MULLARD-MATCHED-PAIR-NOS-/260735396781?pt=UK_Consumer_VintageAudio_RL&hash=item3cb50a6bad#ht_500wt_1156 )  now, how would they compare?
 

 

[shipsupt]

They can be a little difficult to track down.  I finally found a few pairs after checking in with a few web sellers.  You can send them e-mails to see what they have in stock.  If you are not able to track down those specific tubes, you might try other brand 6AK5's as they will be of similar design and construction.  Here are a few web sellers I have used with success:
http://www.vacuumtubesinc.com/
http://www.33audio.com/
And of course a Google search will give many more options such as Tube World, thetubestore, etc...
 
I haven't spent much time with the EF91 so I can't offer too much in the way of impressions, but you can find some earlier in this thread.  They should have a different sound than the 6AK5's as they are from a different tube family and are constructed differently.  Give them some time and tell us what you think!  That's the fun of rolling, building your own impressions.
 
 

 

[LugBug1]

Quote:

I just purchased some new bowls as well as some TTVJ flat pads for my Grado RS-1s. its summer and I'm interesting in trying a different (not nessesarily 'better') sound. would rather play with my Grados - which i love - instead of buy new headphones. I'm currently using Mullard EF91 tubes and the stock opamp.
 
 
 
 
 

 
what affects the sound more? the opamp or the tubes?
 
i'm interested in juicing up my RS-1's bass/deep-midrange (which is why i decided to buy the flat pads.) 
 
what opamp / tube combo would do this?
 
EDIT: i was reading some posts in this thread and ended up buying a OPA2107.
it also seems as if the Mullard EF91 (which I have) are already one of the warmer tubes?
and I have no idea what to do as far as swapping in/out the opamp. is there a good 'guide' anywhere?


 
 
Have to say that my favorite combo for the RS1i with LD, (had the LD1 for a couple of month now) and the one that I keep going back to is opamp 2107 with Mullard EF91's.
The biggest sound difference for me was changing the stock opamp. I've tried 3 of the most popular and they are all better for Grado's. The stock is too harsh and transistor sounding. but if you only try one opamp, go for the 2107. It adds a bigger bottom end and adds body to the music without sounding clinical. A very musical opamp (typical burr brown).
The EF91's aren't overly warm, but what they do offer is good extention at both ends without any hardness. I find them very open and exciting, the best I've tried yet.... all though I do have some Western 408a's on the way so I'll see how they do and get back to you. 
 
 

 

[griffindy]

so does anyone have any suggestions as where to procure an OAP2107? I looked on TI's website and there seem to be a few varieties of them? I found this on ebay, can anyone tell me whether this is the appropriate chip? sorry for so may question marks....and thanks in advance for any advice!
 
http://cgi.ebay.com/Burr-Brown-OPA2107-precision-dual-difet-op-amp-ic-dip-/260655044299?pt=LH_DefaultDomain_0&hash=item3cb04056cb#ht_730wt_1022

 

[LugBug1]

Quote:

so does anyone have any suggestions as where to procure an OAP2107? I looked on TI's website and there seem to be a few varieties of them? I found this on ebay, can anyone tell me whether this is the appropriate chip? sorry for so may question marks....and thanks in advance for any advice!
 
http://cgi.ebay.com/Burr-Brown-OPA2107-precision-dual-difet-op-amp-ic-dip-/260655044299?pt=LH_DefaultDomain_0&hash=item3cb04056cb#ht_730wt_1022

Yep I'd say that is the real deal. You need the 8 dip version as that is.   
 

 

[griffindy]

Quote:

Yep I'd say that is the real deal. You need the 8 dip version as that is.   
 

thanks so much! cheapest impulse buy ever
 

 

[cruizin caleb]

Quote:

so does anyone have any suggestions as where to procure an OAP2107? I looked on TI's website and there seem to be a few varieties of them? I found this on ebay, can anyone tell me whether this is the appropriate chip? sorry for so may question marks....and thanks in advance for any advice!
 
http://cgi.ebay.com/Burr-Brown-OPA2107-precision-dual-difet-op-amp-ic-dip-/260655044299?pt=LH_DefaultDomain_0&hash=item3cb04056cb#ht_730wt_1022

i bought this: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170632916927&ssPageName=STRK:MEWNX:IT#ht_2275wt_967
 
but it seems as if the price doubled since i bought it. i only payed like $10
 
 

 

[griffindy]

 
Quote:

i bought this: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170632916927&ssPageName=STRK:MEWNX:IT#ht_2275wt_967
 
but it seems as if the price doubled since i bought it. i only payed like $10
 
 

the only thing that worries me is that one I bought didn't have a half moon indentation and yours does, but in any case this is probably the cheapest upgrade I can do!
 
 
EDIT: cruizin caleb, I just noticed that the link you had was for two opamps, and I found the same dealer but only one opamp and that is $10.80

 

[john57]

I brought the two OPA2107 op-amps in case that I bend the pins to far out of place to be straghten out all for about $8. There are many vendors to chose from that sells the OPA2107 on EBay.
   

 

[LugBug1]

Quote:

 

the only thing that worries me is that one I bought didn't have a half moon indentation and yours does, but in any case this is probably the cheapest upgrade I can do!
 
 
EDIT: cruizin caleb, I just noticed that the link you had was for two opamps, and I found the same dealer but only one opamp and that is $10.80
 

 

The picture is of a standard 8 dip chip, but your 2107 will have both writing and half moon on so no worries!  
 
 

 

[LugBug1]

My Western 408a's came today, so ive been giving them ago. They seem to have similar characteristics to the EF95's, (very "tubey") only everything is clearer and more precise. Nice big bass but not as loose as the 95's. They do seem bright at the top but no sign of sibilance, maybe a little hardness. The soundstage is the biggest I've heard yet, I've been able to play some complex orchestral music with my Rs1's and with next to no congestion. Very good! most recommended.
 
It's a tough call between these and the Mullard ef91's, but because of the slightly bigger soundstage and clarity me thinks the 408's are the winners, although they may prove to be tireing for some.

 

[john57]

I have tried many different types of 408A's but always go back to the Western brand. As some of you already know the 408A's were originally made for high speed telephone switching equipment at the time. There is only a few amps today that can use the 408A tubes and it is one of the many good reasons that I will keep the Little Dot 1+ for it flexibility.

 

[griffindy]

Quote:

 

The picture is of a standard 8 dip chip, but your 2107 will have both writing and half moon on so no worries!  
 
 

Ah, thank you for assuaging my fears! I'm also planning on purchasing the western electric 408A's from the tube store, I'm glad to hear you like them.
 

 

[cruizin caleb]

wow these screws our awful. two of them came out fairly easy. it seems that i stripped the other two.