Have you plugged the Tungsten into your Quicksilver yet? I don’t have that amp anymore, but I always wondered if it would have been able to drive the Tungsten well.
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also interested in the Tungsten → QS pairing especially if you crank the output voltage going into the QS to give it a bit more oomph.
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So, even before seeing your questions i came back here to report about exactly that! hahaha
I plugged it into the Quicksilver, i thought it would be worth the try since it drives the 1266 so well, and i am glad i did. Honestly i like the Tungsten on the Quicksilver much more than in the OOR, the soundstage gets even better and for some reason the bass slam is much more noticeable than with the OOR, i am very surprised!
How can i try this? Do you mean using a pre-amp? I am currently connecting the Quicksilver directly into my Gumby via the SE output and i never have to go past 12 oclock in the Quicksilver volume pot, so not sure if there is something to be gained by adding a pre-amp?
I must say i am having a blast with these, they are special cans indeed.
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Hey @Christof , would you be able to point me to the file so i can have these printed?
Yeah I use a CMA800R golden as a pre into the QS and it really helps with the 1266. The pairing is quite nice IMO and was wondering if the Tungsten would be alright since it takes more juice than the 1266. I’m not an expert on the DAC side with no pre on how to increase the voltage. Sounds like based upon your take here though it may not need it.
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I have actually used the OOR as a pre for the Quicksilver for a while with good results, but then i switched back to SE directly from my DAC and was not able to tell the difference, so i decided to keep it simple and dished the OOR from the equation.
The Tungsten is harder to drive for sure, i will give the OOR a try as pre-amp when i find some time and report back.
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I can’t upload a file here but try this. I uploaded the file to wetransfer and the link should be valid for a few days
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Got it, thanks!
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Hey guys, question about amps and THD
This is the THD measurement for the Tungsten on the Quicksilver:
And this is the same measurement on the OOR:
As you can see there is a significant increase in the THD below 90hz. I know tube amps introduce harmonic distortions which is expected, but this looks excessive.
Does this look like something one can expect from a tube amp? Or is it an indication of a problem such as the amp not having enough power/control to keep the bass where it should be?
Btw, these were measured using a MiniDSP, not sure if this equipment is capable of accurate measurements for distortion…
It’s more likely the combination of output impedance, and potentially some impact from the output transformer, not the tubes, though it’s hard to determine what is causing what when it comes to measuring systems.
You’d have to measure the quicksilver into a load and get an impedance measurement for the headphone to know for sure,
It could also just be clipping if what I think I read somewhere about how much voltage the tungsten’s needs to play at loud volumes. You’d have to get some idea of the actual pk2pk volume and see what your getting on a scope to confirm.
The quicksilver has one tap, so it’s optimized to push current into 30-60 ohm headphones, not lots of voltage into 300.
The reason expensive tube amps are expensive is they use oversized output transformers, sometimes with esoteric core materials, and/or windings, that greatly increases the bandwidth of the transformers. Cheap output transformers usually have some compromise, usually at both ends.
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I got curious about measuring the Tungsten on the Quicksilver because there is something in the bass response which i dislike sometimes, i can’t really put my finger on it yet but it is there on some tracks.
Talking about power requirements only, does the quicksilver have enough power to drive the Tungsten at 85db? The specs are:
Output impedance: 2.2 ohms
Maximum output: 7 volts rms into 30 ohms or higher load
Those specs are too vague for me to understand…
This is the only thing that matters for the tungsten, because it has such a high impedance, it’s all about voltage rather than power.
Tube amps have distortion that increases linearly with output voltage (which corresponds to volume) until they clip.
If what I’ve read about the voltage needed to get the tungsten loud is correct, that’s going to be less than you need, and it’ll end up clipping or having higher distortion into that load than most.
To give a point of reference I recently checked what my hybrid amp was putting out into the Susvara at what I consider loud, it was about 0.5V average with spikes to 1.5V, I read somewhere the tungsten need as much as 12V, not clear if that was RMS or PK, or what loud is in that context. There aren’t going to be a lot of headphone amps SS or tube that can do that comfortably,
I guess you can get some idea by just turning the volume down and seeing if the thing you don’t like goes away.
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This is all so confusing to me, with the exception of that bass issue in a few tracks they sound absolutely fantastic on the Quicksilver, to the point it does not really make much sense that the QS does not have enough power.
I actually never have the volume pot higher than 12 oclock and i can’t identify any clipping (or maybe that is what is going on with those few tracks where the bass gets weird?), i need to study this subject a bit more so i can make sense of this stuff…
Amps 101.
Basically amps power ratings are gross simplifications.
there are really only 2 equations you really care about with basic analog electronics, Ohms law V=IR, and Power= I * V or I * I * R or V * V / R
I’ll use my Hybrid amp for the sake of the examples below.
Amps have maximum voltages they’ll supply and a maximum current, those might be higher for short periods than they are continuously.
My Hybrid is currently wired with a 20V power supply on the output stage, that mean about the most voltage it can supply is ~19V peak to peak which is ~6.8V RMS. Way more than most headphones need,
It’s also a class A output section, so it always draws 0.65A, that’s the limit of the current it can deliver into a driver. So it’s maximum Pk2Pk Power is V * I = 19 * 0.65 or 12.65W Pk2Pk or 4.4W RMS, and using Ohms law we can determine it does that into 19/0.65 or 29 Ohms.
At any load lower than 29 ohms it’s current limited so you can compute PK2PK power as 0.65 * 0.65 *Load and at any load higher than 29 Ohms it’s voltage limited so power is 19 * 19/Load. For RMS power which is usually quoted you need to divide by 2.8.
To reach that peak power at higher impedance you have to have enough input voltage and gain to get to that 19V in my amps case gain is 18:1 so I need a bit over 1V to hit the 19V.
That 1V is the input Voltage from the source attenuated by the Volume pot.
Most volume pots in audio gear are logarithmic, so at 1/2 volume you’re really attenuating the source to closer to 1/10th of the input not 1/2. Which is why you should never worry about using the top bit of your volume pot. Note some amps attenuate between stages, because it’s “better”, but it requires massive headroom on the input stage for hot sources, so it’s not common.
Transformer coupled Tube amps have some additional complexity, because the load is a part of the circuit, gain varies with load, though it isn’t dramatic. And because the output going into the transformer is centered around the maximum supplied voltage, they rely on the transformers ability to store energy to be able to reproduce the peaks, lower frequencies stress that ability to store energy more so undersized transformers tend to roll off in the bass, or exhibit undesirable ripples. Again why more expensive tube amps get so expensive, you need the big transformers, with wide bandwidth.
The transformer in a tube amp is designed to provide a specific load on the anode of the tube it does this by reflecting the load from the transducer. So if you design the amp to provide say 5000 ohm load when connected to a 30 Ohm load, that same transformer will provide a 50K Ohm load when connected to a 300 Ohm load (hence why some tube amps have multiple taps). In practice that usually reduces distortion (though not always), but because transformers convert voltage into current, you also limit the power into higher impedances.
It might not be clipping, it’s hard to tell without measuring the amp in isolation into a dummy load.
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That happens to me with the 1266 and QS hence why I used the pre to help with gain before getting to QS. My goal with QS is to keep the volume pot at 12 o clock or under. Just something I didn’t like when the volume pot goes higher. The prior owner did some mods so could be my unit.
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FWIW Your working in the worst part of the pot when you stick to the bottom of the volume range.
The pot isn’t a part of the amplification circuit, all it’s doing it reducing the input signal. Which means any ambient noise from the input section is higher relative to the signal
Increasing the signal before the amp won’t help with overall volume before distortion/clipping, unless the amps gain is so low it can’t reach it’s maximum output, in which case you’d be maxing out the volume pot.
Most amps with a volume pot (not all) have constant gain, all your doing is reducing the input signal with the pot. If you get it to the same loudness level without the pre amp, there isn’t a win for the “power” amp. That doesn’t mean the pre amp is value less, just that it’s not providing additional overall gain, it will also likely have a low output impedance, and that can matter if the DAC’s is borderline, and of course it will add it’s own flavor into the mix.
Jason from Schiit had a good piece on gain over on Head-fi.
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Thanks for this explanation, geez this can get really complex!
I have my OOR currently wired up as a pre for the QS, using the OOR on high gain with the volume around 2 oclock and with that i was able to reduce the QS’s volume pot from 12 oclock to around 11 oclock.
I love what i hear so far, i can no longer hear that weirdness in the bass on a couple of the songs i did before so i don’t think its placebo because that was annoying me big time when it happened.
Still need to setup some proper testing with volume matching and all, but i think i will keep things like this for a few days.
Now speaking of the Tungsten itself, my God i absolutely love these cans. I use EQ for all of my cans and this one is the very first one where i don’t need it, the bass quantity is less than my preference but there is something about how it is presented where it manages to scratch my basshead itch even with less quantity, the texture, the articulation it is just something i have not experienced before.
I get a feeling that after some more time of brain burn in, some of the other cans in my collection will end up going into the classifieds on head-fi, hahaha
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Try this;
1- zero gain on pre and amp.
2- move pre-gain to 12 o’clock
3-play well recorded track you enjoy and slowly raise gain on amplifier till you have reached maximum volume you would possibly listen to.
4- you have now used one possible method to adjust your amplifier gain relative to your pre.You should never/rarely clip or drive your amplifier into distortion using this method to set your gains.
Happy listening
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Thanks, i will give this a try!
I have noticed the strangest thing while i was connecting the QS directly to the Gumby, whenever i turn the OOR on while listening to the QS, the volume on the QS increases, and if i just turn off the OOR, the volume on the QS goes down.
Apparently there is some type of connection between the output signal on the SE and the XLR connections on the Gumby, this threw me off even more so not using the SE output on the Gumby started sounding like a better idea…
Do you guys understand why having an amp connected into the XLR output would change the signal on the SE output? This sound like something that should not happen.
Depending on how it connected it should be fairly obvious.
The DAC itself has a single output, that is split into 2, so with one connected you have some load, with both you get them in parallel. This load is in effect creating a voltage divider with the output impedance of the DAC. The fact it increases when you turn the OOR on implies that the load increases when the OOR is powered on.
Now having said that it really shouldn’t make a difference, the output impedance on the Gumby should be small and the input impedance on the Amps should be large, and I wouldn’t expect any difference to be audible.
But I’ve seen reported before that there are some amps that will cause problems when left connected to one output of the DAC while the other is in use.
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