Adding Resistors to Grados

[lextek]

If one was to add a couple 100 ohms of resistor to a Grado would you me able to us it withthe Crack?

[mosshorn]

I'm wondering the same thing, and how it could be done. I was actually thinking of picking up a P to S converter from Etymotic to find out, adds 75 ohms I believe, which would set the total of (most) Grados to 102 ohms. Not perfect, but useable.

Anyone else have experience with this?

[Beefy]

I'm wondering the same thing, and how it could be done. I was actually thinking of picking up a P to S converter from Etymotic to find out, adds 75 ohms I believe, which would set the total of (most) Grados to 102 ohms. Not perfect, but useable.

It doesn't work like that. Adding series resistance increase the output impedance of the amp, not the impedance of the phones, thus makes the damping factor worse. So if you want to add resistance to supposedly make the amp better for low impedance phones, you are largely barking up the wrong tree.

[mosshorn]

Thanks for the response, saved me some money and hassle

[Laudanum]

If you love the Grados it just makes more sense to go with an amp that is better suited for them.   For pure headphone amp, Smack is the most versatile as it's switchable to match just about any phone but obviously more expensive.    Just my opinion for a possible option here but Crack and a Beyer DT 990 pro's make for an awesome, reasonably priced combination.   Down right killer for the money (and a lot more).  And a little bit more for the DT 880's which are a bit more balanced if the bass is too much for you with the 990's.  Of course, you have to like the phones otherwise it's a waste.   Crack is great, the only limiting factor is availability of higher impedance phones.   So if you are enamored with the Grados, go for the Smack or Sex ... even if you have to save some pennies for a while.

[lextek]

I own both the HD600s and Grado SR-225s.  My first choice is usually the HDs.  My Crack is on order.  I just had some time to wonder while I was waiting for the Crack to ship.  The Crack will be my first build followed by the Speedball upgrade.  Smack or SEX somewhere down the line.....

[Beefy]

If you love the Grados it just makes more sense to go with an amp that is better suited for them.

There is also the fact that many people actually prefer Grados from an amp with a higher output impedance. The decreased damping factor seems to reduce some of the excessive harshness or sharpness that Grados can have.

Still, that isn't a great argument for adding resistors to the output of the Crack to make it 'better' with low impedance phones.

[xcortes]

Hopefully PJ can chime in. I believe the OP is right in that adding the resitors increases the load to the amp (the etys being the perfect example as he pointed out).

In any case I have a Crack kit with premium tubes and caps in the bench to try with my 40 ohm Sonys with resistance in series.

Trying the Crack is not necessarily a buyin'-a-cheaper-amp thing but a how much are the opts getting in the way experiment.

Hopefully I'll get to taste that addictive OTL sound but there's no way I'm using different cans than my Sonys.

[Paul Joppa]

Hopefully PJ can chime in. ...

I think this thread is doing very well on its own  :^)  I have only two thoughts to add in:

1) We are still experimenting - so far with encouraging results - with a revised operating point for Crack, running more current and producing a lower output impedance. This may not be the highest priority - there are a lot of things on the R&D agenda right now - we we aren't going to drop it either.

2) If your phones are highly sensitive, you can put an L-pad attenuator at the output, which will both increase the load seen by the Crack (less distortion, not that there's much there to begin with) and provide a lower impedance as seen by the 'phones. Lots of room for experimenting there!