Have a look at posting:
http://www.head-fi.org/t/605444/sennheiser-hdvd800-headphone-amplifier/1290#post_9639003
to see how output impedance of an amp can affect frequency response and signal level.
Let suppose the internal signal generated by your amp is 10 volts. If the impedance of the amp is 50 ohms and your headphones impedance is 50 ohms, the 10 volt signal will split evenly across the two impedances and the headphones will only get half of it (i.e., 10volt * (50/50) ohms = 5 volts). Now the mid bass of the T1 have an impedances of 1400 ohms. That means the 10 volt signal from the amp will produce 10volt * ((1400 - 50)/1400) or about 9.6 volts across the T1 headphones. So, 5 volts across the low impedance and 9.6 volts across the T1---which do you think would be louder?
It's not just having enough voltage to drive the headphones, it's enough voltage with a low output impedance. You say that you got extra bass. Well that is to be expected since the impedance curve in the bass on the T1s is very high (1450 ohms) meaning it is boosted. However, since the upper mid range and treble are down at 650 ohms, those frequency ranges are going to have a significant reduction in signal available to them. I didn't hear you raving about any pristine clarity or brilliance when you were seeing the bass boost
- Jeff
I am really liking them. I have been using the Sennheiser HDVD800 and in have discovered that the tuning that they did to tame some of the treble on the HD800 has also helped a bit on the T1 for the same reasons.
The only things that I was concerned about and have later confirmed on the T1s are what many have found. First you need a quality amp in order to hear what it can do. It can really sound poorly on lesser amps and revealing to their shortcomings. Secondly, there is a bright boost in the treble that can be a nuisance at times depending on circumstances. The HDVD800's output impedance seems to reduce this issue a bit as I don't find it a problem most of the time. Usually, it is very pleasant to listen too and the fast treble helps to give reasonable focus if the information is in the signal. However, some recordings with too many "S"s and close mic'ing or too much boost in the treble can become a bit shrill. However, the T1 do so many things so well, I'm not ready to give up on them.
I understand why tubed amps could be good with this but I've preferred to go with solid state for several reasons. Of course, with that selection you have to have really well voiced amps but they do exist if you look for them. I prefer to have as neutral an amp as possible and transducers to match. However, What I am finding with headphones is that when they are engineered, it must be very difficult to produce phones with really flat frequency response and fast decay, because most of them that I have seen just don't.The need to provide a notch in the frequency response in the 6-8KHz region to avoid the inner ear canal resonance issue as well must be a significant challange. So it is no wonder so much attention to amp synergy with a particular set of phones is of major interest on the forums.
Probably no new amps for me in the near future as the main thing was just to be able to listen again, and it's been GREAT, and I have used all my money anyway since I'm currently unemployed. However, I'm very tempted, and will likely proceed, to build an adapter with resistors to allow me to simulate a 100 ohm output impedance to see how well it works in taming the T1 treble issue. If this works as well as I'm hoping, I think that I might be more tempted to look at something like a Conductor or even a Naim DAC-V1 since It has a lot more utility than the HDVD800 does. For my current application I really want an all-in-one type combo. If it weren't for that, I'd just look at adding a better external DAC eventually because I think the T1 and HDVD800 amp section would scale with it.
Of course without a job, you got no money, and with no money, you can only listen to music. Well, maybe that's not so bad but trying out new things and comparing stuff was always part of the fun!
- Jeff
I am really liking them. I have been using the Sennheiser HDVD800 and in have discovered that the tuning that they did to tame some of the treble on the HD800 has also helped a bit on the T1 for the same reasons.
The only things that I was concerned about and have later confirmed on the T1s are what many have found. First you need a quality amp in order to hear what it can do. It can really sound poorly on lesser amps and revealing to their shortcomings. Secondly, there is a bright boost in the treble that can be a nuisance at times depending on circumstances. The HDVD800's output impedance seems to reduce this issue a bit as I don't find it a problem most of the time. Usually, it is very pleasant to listen too and the fast treble helps to give reasonable focus if the information is in the signal. However, some recordings with too many "S"s and close mic'ing or too much boost in the treble can become a bit shrill. However, the T1 do so many things so well, I'm not ready to give up on them.
I understand why tubed amps could be good with this but I've preferred to go with solid state for several reasons. Of course, with that selection you have to have really well voiced amps but they do exist if you look for them. I prefer to have as neutral an amp as possible and transducers to match. However, What I am finding with headphones is that when they are engineered, it must be very difficult to produce phones with really flat frequency response and fast decay, because most of them that I have seen just don't.The need to provide a notch in the frequency response in the 6-8KHz region to avoid the inner ear canal resonance issue as well must be a significant challange. So it is no wonder so much attention to amp synergy with a particular set of phones is of major interest on the forums.
Probably no new amps for me in the near future as the main thing was just to be able to listen again, and it's been GREAT, and I have used all my money anyway since I'm currently unemployed. However, I'm very tempted, and will likely proceed, to build an adapter with resistors to allow me to simulate a 100 ohm output impedance to see how well it works in taming the T1 treble issue. If this works as well as I'm hoping, I think that I might be more tempted to look at something like a Conductor or even a Naim DAC-V1 since It has a lot more utility than the HDVD800 does. For my current application I really want an all-in-one type combo. If it weren't for that, I'd just look at adding a better external DAC eventually because I think the T1 and HDVD800 amp section would scale with it.
Of course without a job, you got no money, and with no money, you can only listen to music. Well, maybe that's not so bad but trying out new things and comparing stuff was always part of the fun!
- Jeff
