[looser101]

I'm using 100k with Grados and they are very efficient.

 

[PJPro]

Quote:

Originally Posted by looser101 /img/forum/go_quote.gif I'm using 100k with Grados and they are very efficient.

OK. Thanks. I'll make the change.

 

[revolink24]

I asked the same question for my Grados earlier. Since I plan to have higher-impedence headphones someday, I stuck with the 50k, and will just deal with the microadjustment on the pot, as you say. Hopefully it won't disappoint me.

 

[Juaquin]

For the record (anyone looking later on), I used the 100k resistors with my Audio Technicas, no problems. It wouldn't be hard to swap resistors later. If you switch headphones with different efficiencies often, you could put some resistors on protoboard and wire up a switch.

 

[Tritonpad]

Hi there !

Hey it's finished !!! And finally it works perfect ! I say "finally" cause I had some soldering problems due to bad cheap stuff...
Now, all I can say is "Uhhh"... "Waaaaa"... And then I shut up and listen.
Picasa Albums Web - Olivier - ampli tube

Those are some pics for the occasion. You 'll even see my big face ^^

A big big ultimate thank you goes to Pete, TomB and dsavitsk.

P.S. : for K701, I can validate the use of 50k resistors for r16/r17, as TomB suggested. Gain is ok and no balance pb due to the pot.

 

[tomb]

Quote:

Originally Posted by Tritonpad /img/forum/go_quote.gif Hi there ! Hey it's finished !!! And finally it works perfect ! I say "finally" cause I had some soldering problems due to bad cheap stuff... Now, all I can say is "Uhhh"... "Waaaaa"... And then I shut up and listen. Picasa Albums Web - Olivier - ampli tube Those are some pics for the occasion. You 'll even see my big face ^^ A big big ultimate thank you goes to Pete, TomB and dsavitsk. P.S. : for K701, I can validate the use of 50k resistors for r16/r17, as TomB suggested. Gain is ok and no balance pb due to the pot.

Wow! Great pics - very impressive!!

 

[Juaquin]

Quote:

Originally Posted by Tritonpad /img/forum/go_quote.gif Picasa Albums Web - Olivier - ampli tube

The plastic part of the case (gasket kinda thingy?) goes on the case before the faceplate, so it is sandwiched between the metal pieces. It's not necessarily important (I guess you could do it either way) but I did the same thing before realizing my mistake.

 

[PJPro]

Bunged in the 100K for R16/17. Much better. Good range of turn on the pot. Gets too loud before distortion. Absolutely silent.

It's been running all day (with the 50K in place). And I feel it's already begining to mellow but has a way to go yet.

 

[Tritonpad]

Juaquin : yes you are right, I didn't notice before you say it !

PJ Pro : 100k resistors for R16/R17 seem definitely to be what Grado's need, but it's not the same for AKG's.

 

[KeeChoon]

Quote:

Originally Posted by PJPro /img/forum/go_quote.gif Bunged in the 100K for R16/17. Much better. Good range of turn on the pot. Gets too loud before distortion. Absolutely silent. It's been running all day (with the 50K in place). And I feel it's already begining to mellow but has a way to go yet.

Hi PJPro,

I'm getting parts for the amp and will be running a grado sr-60 with it. I'm wondering if its 100k R16/17 with a 50k pot or 100k pot? Because in the BOM, it was recommended to use 50k R16/17 with 50k pot and 100k R16/17 with 100k pot.

 

[thelast]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Check that center standoff for a short on the LED resistor trace. The power supply has an automatic cutoff in case of a short. If you can measure 48VDC from the power supply connector when it's not connected, then you've got a short that developed when you re-assembled the case.

I checked the center standoff and there is no short. I also checked the power supply connector and I don't get any voltage reading.

 

[gore.rubicon]

Quote:

Originally Posted by thelast /img/forum/go_quote.gif I checked the center standoff and there is no short. I also checked the power supply connector and I don't get any voltage reading.

Post pics?

Quote:

Originally Posted by PJPro /img/forum/go_quote.gif Bunged in the 100K for R16/17. Much better. Good range of turn on the pot. Gets too loud before distortion. Absolutely silent. It's been running all day (with the 50K in place). And I feel it's already begining to mellow but has a way to go yet.

Can the same effect be had if i used an inline impedance adapter?

 

[PJPro]

Quote:

Originally Posted by KeeChoon /img/forum/go_quote.gif Hi PJPro, I'm getting parts for the amp and will be running a grado sr-60 with it. I'm wondering if its 100k R16/17 with a 50k pot or 100k pot? Because in the BOM, it was recommended to use 50k R16/17 with 50k pot and 100k R16/17 with 100k pot.

It's a 50K pot...as supplied with the kit.

I suspect even higher values for R16/17 would be OK or even better e.g. 150K.....but I think I'll live with the 100K.

 

[PJPro]

I have to say it's been very enjoyable just getting a kit through the post and putting it all together and listening to it. I've been building a couple of mono power amps and it's taken a massive investment in time and money. See here.

Many thanks to tomb for sorting out the kits. I'm sure it's been very hard work.

So. What's next?

 

[tomb]

Thanks for the kind comments!

Keep in mind, guys - the gains you are all searching for have wide variances. 100K resistors for one guy with Grados may not work for the next guy who has Grados and also a pair of Portapros (or Orthos, or Senns, etc., etc.). More important, you all have varying tastes of volume control and you all have different sources. Some sources are weak, some are strong. Some of us are OK with partial volume travel, others want to rack the volume pot just at the point where they are uncomfortable.

So use the comments as a guide, but - YMMV.