MidFi Guy said there is background noise (hiss). Are you not worried about it at all? I wouldn't want to spend so much money on amplifier that has audible hiss.
Cayin HA-6A Class A KT88/EL34 Tube Headphone Amplifier
- Thread starter Andykong
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Just did some more testing with different tubes, changing TR/UL modes, changing to a less used power outlet, using a non-grounded power cable, etc... The hiss is there but it's only really noticeable on the HD650 when the impedance selector is on High, and it virtually disappears when you're listening to music.
Here's a list of the dynamics I'm able to test, all in high impedance mode (since the hiss is only really audible here), in order of loudest hiss to lowest (ohms / sensitivity):
- Senn HD6XX (300Ω / 103db)
- Meze 99 Noir Classics (32Ω / 103db)
- Sony Z7 (70Ω / 102db)
- ZMF Aeolus (300Ω / 99db)
Baten
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Most tube amps have a noise floor. It's pretty much expected if you go tube over solid state :/
My ECP T4 tube amp doesn't have noise floor. I had C3X solid state amp which has very high noise floor.
I think it depends on output power. Most high powered amplifiers don't have audible noise only when used with planar magnetic headphones.
Don't know if you all have been following the comment thread on Youtube but we narrowed down the hiss to the 4-pin balanced XLR output. If I use the HD6XX with the 1/4" single-ended jack I get no hiss.
I can definitely live with this, especially since a) the decreased power output provides better steps with the volume pot levels and b) the amplification happens in single-ended mode anyway. That said @Andykong maybe the Cayin engineers can look at why the 4-pin balanced output creates hiss with high impedance headphones? Is it just my unit?
I can definitely live with this, especially since a) the decreased power output provides better steps with the volume pot levels and b) the amplification happens in single-ended mode anyway. That said @Andykong maybe the Cayin engineers can look at why the 4-pin balanced output creates hiss with high impedance headphones? Is it just my unit?
That is because the Rated Power Output and Residual Noise Level of High Impedance setting is higher then both Mid and Low impedance significantly, and the rated output of XLR4 is slightly higher then 6.35mm. In other word, the HA-6A is operated at its PEAK at high impedance XLR4 output.
The Residual Noise level is not a published specification in normal practise, you won't find this in the specification of most, if all not all, amplifier, be it speaker amplifiers or headphone amplifiers. If you understand the factors behind residual noise, then you'll understand the correlation among residual noise, impedance and output level.
HA-6A offers a very wide range of output power to our users, this is, supposingly a pros to offer more flexibility to our users so that they can match with different headphones with confident. However, if you insist to use the highest output power setting to drive the sensitive headphones, then you are turning a pros into a cons. To put this into context, with the same set of power tube (i.e., without changing from KT88 to EL34) the lowest output power setting is Triode mode + Low Impedance + Single-ended output (6.35mm), and the highest output power setting is Ultralinear mode + High Impedance + Balanced (XLR4 or 4.4mm). Roughly speaking, the later (UL+H+BAL) is around 7 times higher than the first (TR+L+SE) setting.
If you are numerical mind and want to find out how these numbers worked out, I can elaborate further below, but I guess some users will be bored by these numbers.
In our product specification, we only published the output rating in watt, this is subject to loading (impedance) so not a straight forward numbers if you want to compare the output rating across different loading. However, you can work out the voltage level (designated as Vrms in specification) according to the following formula and that will allow you to compare the figure in with linear numbers:
V = SQRT (W*R), or W= V^2 / R
Let's elaborate the KT88 output rating for discussion. I don't know the actual impedance loading of this setting, but since we are comparing the effect of different setting instead of measuring the output rating under different condition, let's ASSUME the loading of L is 64ohm, M is 250ohm, and H is 600ohm for the time being.
The first set of data compare four different setting of LOW impedance output, and the output level are 7.16V, 8.76V, 8.76V and 11.03V respectively. In other word, at Low impedance, change from SE to BAL will increase output by 22% , From TR to UL will also increase output by 22%, and change from TR+SE to UL+BAL will increase output by 54%, not very substantial but still noticeable.
However if we change to Mid and High impedance loading, the output level at UL+BAL will bump to 27.39V and 51.96V respectively. When compare to the baseline output at 7.16V (TR+L+SE), we achieved "roughly" 3.8x and 7.3x, quite an astonishing multiplier if you don't compare them in linear numbers.
One last comment: the effect of different setting might worry in different impedance loading. For example, if we change our focus to High impedance, the four different setting will deliver output level at 38.73V, 43.82V, 46.48V, and 51.96V respectively. When compare to the High Impedance baseline, the multiplier is now lowered to 1.13, 1.2, and 1.34 respectively, quite a bit lower than the multiplier of Low impedance loading.
Please be reminded that these are "assumptions" to facilitate discussion, I don't have the actual impedance loading of L, M, H output off-handed (and this is 10:30pm, now the right time to call up the Engineer to clarify the setting). However, I hope we have clarified the situation and we don't need to worry about hissing problem with high sensitive headphones because of the low level background noise at High Impedance XLR4 output.
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Haha!
Was going to post this over the weekend but I noticed the Pre-order button is now an "Add to cart" button. I guess they're in stock now:
https://shop.musicteck.com/products/cayin-ha-6a-el34-kt88-vacuum-tubes-headphone-amplifier
Was going to post this over the weekend but I noticed the Pre-order button is now an "Add to cart" button. I guess they're in stock now:
https://shop.musicteck.com/products/cayin-ha-6a-el34-kt88-vacuum-tubes-headphone-amplifier
GU1DO
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I think this video should be shared here . Nice work Relaxasaurus , i watched your first review bth i had mixed feelings , so i thought i would give this amp more time for more feedback and i guess this video give a very good impression how the Cayin HA-6A sound with variety of headphones , thanks for the great honest review and please keep up the great work .
GU1DO
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Forgot to ask , at which impedance you liked the HD800 at ?
any difference with different settings ?
any difference with different settings ?
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