Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Paramount => Topic started by: casanis on March 22, 2014, 10:12:09 PM
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I have a chance to pick up either a pair of Grado RS1i's or Senn HD650...used and at a very good price.
I'm quite happy with my current setup and am not looking to add an additional amp for headphone duty.
What's the general consensus for headphone impedance when driven with Paramounts (2A3 configuration) and Foreplay III?
Thoughts and or opinions most welcomed!
Cheers.
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Look for something that enjoys a 16 Ohm impedance as that's what you're going to get with the Paramounts. The Senns are out. Why not find a pair is AKG K1000's?
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Sennhieser will work well, Grados will probably be too sensitive.
I'd add some series resistance for the Sennhiesers.
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Sennhieser will work well, Grados will probably be too sensitive.
I'd add some series resistance for the Sennhiesers.
Why will they work well and would they work well without the series resistance?
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The Grados are a very sensitive headphone so you will need an amp with a nice quite noise floor and low output impedance to drive them properly. The Sennheisers are a lot more forgiving and seem to work well with just about any amp.
As to which to go for, that's a choice only you can make. I adore my Ms-Pros (RS1 variant), and never liked my HD650's, but many people would be the complete opposite so you really need to listen to both and decide for yourself, both are a very nice pair of headphones.
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RE: the sensitivity of the Grados, I have been reading that a series added 120ohm resistor is standard on other amps. Would this addition help the sensitivity issue of the Grados matching up with the Paramounts?
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The added 120 ohm resistor would help the Grado sensitivity issue greatly. Unfortunately the Grados in general do not like that resistor, it muddies the bass (I am told). I'm ot a headphone user myself, so maybe someonewith direct experience will add a comment?
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Went for the HD650's... picking them up later today. Thanks for the info all.
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Report back how you like the combination.
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Picked up the HD650's this morning and hooked them up just to verify functionality.
They sound quite good, however, appear to be a little too sensitive. Thankfully I did not go for the Grado's!
Can anyone offer input on 120ohm resistors for the headphone output (type, brand etc...).
I have some 150ohms on hand, however, will be putting in a partsconnection order this week...
The Paramounts hum balance pots made a huge difference in quelling hum...
Will update accordingly.
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Toss the 150 Ohm resistors that you have now in and see how you like them. (Clip leads to test if you like)
Also, wire your Paramounts for the lowest possible output transformer impedance.
How is the noise level without resistors?
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"Also, wire your Paramounts for the lowest possible output transformer impedance."
How will this affect the speaker outputs (currently wired for 8 ohms)?
I was hoping to add a switch to the speaker terminal o/p on each Paramount to go between headphone out (via internally mounted barrier strip) and speaker output.
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If you use the 4 Ohm configuration on your 8 Ohm speakers, you will sacrifice some output power but at the same time obtain better damping and a lower noise floor.
If you want to be a true bad ass, you can convert your Paramount speaker outputs to balanced outputs (lift the ground from the negative speaker post, then put a 100 Ohm resistor from + to ground and - to ground), then add a 1/4" switching TR jack to each amp. Cable up your headphones for balanced operation with two 1/4" mono plugs, then when you plug them in the speakers will cut out :)
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Okay - thanks for the info!
Lots to chew on here...
The noise level from the Paramount is almost non-existent with the hum pots tweaked accordingly. (input shorted)
I am hearing some noise from upstream of the Foreplay when the TD-124 is selected through my Yaqin RIAA...the weakest link I'd say.
This sure is a slippery slope! Headphones are a great way to really hear what your system is sounding like...
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The resistor - 120 ohms, 150 ohms, or whatever - won't make a lot of difference with the 300 ohm 650s. The resistor is mostly effective for low-impedance phones (like 40 ohm Grados). If you need to attenuate the headphone signal, it's better to make up an L-pad - two resistors per channel. That way you can retain a lower output impedance too.
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The resistor - 120 ohms, 150 ohms, or whatever - won't make a lot of difference with the 300 ohm 650s. The resistor is mostly effective for low-impedance phones (like 40 ohm Grados). If you need to attenuate the headphone signal, it's better to make up an L-pad - two resistors per channel. That way you can retain a lower output impedance too.
What values to start toying with?
I've taken a look online to find an L-pad calculator:
http://www.sengpielaudio.com/calculator-Lpad.htm
Thoughts on where to begin?
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Since my high frequencies are rolled off I am ordering some non-inductive Mills resistors to pad the super tweeters I have on my Orcas.
Any inductive resistor will not only block highs but also mess with the phase of them. Many film (metal or carbon) resistors have a spiral trim and are somewhat inductive. The Mils resistors are perfect for me.
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Thoughts on where to begin?
You could try a variable L-pad.
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...Thoughts on where to begin?
First determine what your requirements are. Any attenuator will reduce the peak signal level available, as well as the noise - you want a balance between those factors.
Radio Shack still lists a 25-ohm rheostat, which you can wire up as a potentiometer to feed the headphones. When you find the setting that works best, you can measure the resistances to determine the attenuation you want - or just keep the rheostat, it's wirewound and should sound decent.
BTW, very few resistors of any type or value have enough inductance to affect the treble. But it's difficult to find specifications for resistor inductance, making this hard to evaluate.
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Update:
The HD650's sound VERY NICE with the Paramounts/Foreplay III combination.
Incredibly low noise floor / hum...almost non-existent.
I ended up installing a toggle switch on each Paramount to select between speaker o/p and the cans (hardwired). No longer required to unplug bananas for speakers to switch to late night headphone listening. ...I also put the 150ohm resistors in line, which took just enough "hotness" off the cans.
New ear foams and blue dragon cabling on the way for the 650's.
Thanks all for the input.