Got a Chinese tube amp and now world is upside down

[svtcontour]

So out of curiosity, I picked up a cheap tube amp from Aliexpress - branded as OldChen. Its an EL34 single ended. I figured for the dirt low price of about $330 (canadian money) including shipping, I can mess around with it and see what I think. I was prepared to hate this thing because I've always had solid state and hate mushy bass, softness and lack of detail.

My speakers are open baffle DIY and fairly efficient. I am guessing at around 95db @ 1w or higher like even 97. I also dont listen very loudly. Typically low 80's on the peaks .. maybe mid 80's. Occasionally tapping 90db on peaks if I'm feeling very crazy LOL.

Anyway connected this, and let it warm up for 20 mins. Then sat down and started listening to music and I'm just shocked. Subjectively, I find it neutral with no apparent "tube sound", bass is nice and firm and its plenty clear and resolving and for whatever reason, I'm hearing more subtleties. When I go back to my solid state, they are there, but just ever so slightly more subdued.

Subjectively, its better on anything that has vocals and real instruments or anything recorded in a live open space. The solid state is still better for pure electronic or dance /EDM if very loud volumes are needed. So at this point, I am finding it hard to go back to the solid state. I invited a couple friends over who are solid state guys and now they are tempted to buy the same little amp because they agreed, it sounds better and more involving.

So ... is it the fact there is even order harmonics? Is there any benefit of pure class A of a single ended. Trying to understand why I'm listening to music for hours a night instead of sleeping since getting this thing. Make it stop LOL.

 

[svtcontour]

Oh I forgot. My solid state amplifiers that I sometimes swap between are the ART SLA1 modded with a quiet fan, a Ramsa WP9220 also modded with a silent fan and a Bryston 2BLP Pro. These are old class AB pro style amps. I've even heard a Benchmark amp on my system (friend dragged it over). Oh also have had a Pass Labs F5 here that a friend built. But I wouldnt trade whatever is going on right now for any of it.

 

[Doodski]

I find it neutral with no apparent "tube sound", bass is nice and firm and its plenty clear and resolving and for whatever reason, I'm hearing more subtleties. When I go back to my solid state, they are there, but just ever so slightly more subdued.

Possibly there is some frequency response coloration there and it is agreeable. On a different pair of speakers the sound from it would be different again but we don't know if it would be agreeable or not.

 

[kemmler3D]

for whatever reason, I'm hearing more subtleties.

is it the fact there is even order harmonics?

Probably.

Lots of harmonics has the effect of emphasizing mids and lower treble (well, anything below half of your hearing threshold, ha) by adding energy to those sounds. Subjectively it's like a treble boost but "warmer" because you're not boosting the actual treble in the audible band, you're adding treble effects to lower frequency stuff. (h2 of 10khz = 20khz, etc.)

It can also make dynamics seem a bit snappier if the distortion profile isn't linear. These amps can act like expanders and/or dynamic EQ so things sound more lively.

If you find the enhancement to sound good... I say congrats and don't worry about it. It's likely that it's "lower fidelity" than whatever solid state you were using before, but on the other hand, "if it sounds good, it is good", right?

 

[svtcontour]

Possibly there is some frequency response coloration there and it is agreeable. On a different pair of speakers the sound from it would be different again but we don't know if it would be agreeable or not.

This is true. The only other speakers I have are on my computer which are a pair of Kef LS50 powered by the SMSL AO100. I suppose I can try it on there and see what happens. They are low efficiency but as desktop , nearfield use its probably more than enough power this little tube amp

 

[svtcontour]

Probably.

Lots of harmonics has the effect of emphasizing mids and lower treble (well, anything below half of your hearing threshold, ha) by adding energy to those sounds. Subjectively it's like a treble boost but "warmer" because you're not boosting the actual treble in the audible band, you're adding treble effects to lower frequency stuff. (h2 of 10khz = 20khz, etc.)

It can also make dynamics seem a bit snappier if the distortion profile isn't linear. These amps can act like expanders and/or dynamic EQ so things sound more lively.

If you find the enhancement to sound good... I say congrats and don't worry about it. It's likely that it's "lower fidelity" than whatever solid state you were using before, but on the other hand, "if it sounds good, it is good", right?

Oh great information. Thank you Yes in my case, its subjectively better on every metric I have except for that it cant get as loud if I want to crank some electronic music / EDM ... but for every other instance its is better - as in feeling more clear and resolving, more engaging and lifelike. Oh the other thing that shocked me was the lack of noise floor. Its dead quiet - even less faint hiss than my solid state - through the compression driver in my speakers.

 

[svtcontour]

This is the little amp.

 

[solderdude]

My speakers are open baffle DIY and fairly efficient. I am guessing at around 95db @ 1w or higher like even 97. I also dont listen very loudly. Typically low 80's on the peaks .. maybe mid 80's. Occasionally tapping 90db on peaks if I'm feeling very crazy LOL.

If that really were the case you would be listening to 0.25W peak levels (when going crazy).
There won't be much harmonics peeping above the background noise at these levels so that is unlikely to be the case.
It is far more likely the actual output power/SPL produced by the driver is much higher than you suppose it is.

A high output resistance (modified frequency response) or some roll-off or even boost at certain frequencies is most likely the culprit.
Tube amps can sound perfectly fine even though signal fidelity is (will certainly be) compromised in cheap tube amps.

You just prefer the coloration or there is another, more likely, explanation to your findings. The signal fidelity (of the input signal) with 100% certainty will have been degraded. Yet your perception of that change is different and gives you more enjoyment.
Best to stop wondering why and enjoy the music.

 

[radix]

If you have a measurement mic, could you do some REW measurements of the SS and the tube? Would be interesting to see what you are hearing.

 

[svtcontour]

If that really were the case you would be listening to 0.25W peak levels (when going crazy).
There won't be much harmonics peeping above the background noise at these levels so that is unlikely to be the case.
A high output resistance (modified frequency response) or some roll-off or even boost at certain frequencies is most likely the culprit.
Tube amps can sound perfectly fine even though signal fidelity is (will certainly be) compromised in cheap tube amps.
You just prefer the coloration or there is another, more likely, explanation to your findings.

Though in my case if the amp is single ended class A, doesnt that mean its kind of running full out (or to however they've biased it) and I'd get coloration or is it still dependent on volume. I basically sit about 2.5 meters away from the speakers so I guess I'd need more power at that distance but maybe like 0.75 w or something

 

[svtcontour]

If you have a measurement mic, could you do some REW measurements of the SS and the tube? Would be interesting to see what you are hearing.

Ya I do have a Dayton USB mic and I should really do a measurement at 1 meter from the loudspeaker as well as listening position to see how it compares with the solid state. With my Solid state (Ramsa amp), this was the response of the speaker at 1 meter. Its not ruler flat but I think not too bad for DIY and being open baffle. Maybe this weekend I'll do it again with the tube amp. Good idea.

 

[solderdude]

Though in my case if the amp is single ended class A, doesnt that mean its kind of running full out (or to however they've biased it)

No it just means a lot of unused power is wasted.

and I'd get coloration or is it still dependent on volume.

Coloration can be signal dependent.
The amount of harmonics that reach audible levels is level dependent.
Roll-off (lows and highs) is certainly output level dependent.
The output thus will be more level and load dependent than what the SS amp does.

I basically sit about 2.5 meters away from the speakers so I guess I'd need more power at that distance but maybe like 0.75 w or something

You said EDM would not play loud enough for you which means you are already exceeding the rated output power of the amp.

 

[solderdude]

Ya I do have a Dayton USB mic and I should really do a measurement at 1 meter from the loudspeaker as well as listening position to see how it compares with the solid state. With my Solid state (Ramsa amp), this was the response of the speaker at 1 meter. Its not ruler flat but I think not too bad for DIY and being open baffle. Maybe this weekend I'll do it again with the tube amp. Good idea. View attachment 316491

That is great for a DIY.

Make sure to repeat the measurements a few times for each amp with the mic in fixed position to get a feel of the tolerance.
Acoustic measurements are a nightmare.
I would suggest to do measurements in the electrical domain under electrical load if you want to get to the bottom of it.

 

[TonyJZX]

if you google oldchen el34 or laochen el34 you'll find everything you need to know

its a 15w SET with the optional obligatory bluetooth hooked onto the side

for $200 its a not a bad idea to dip your toe into tubes

 

[LTig]

Possibly there is some frequency response coloration there and it is agreeable. On a different pair of speakers the sound from it would be different again but we don't know if it would be agreeable or not.

This!

@svtcontour : you can add a power resistor of a few Ohm in series between the output of the solid state amp and the speaker to emulate the output resistance of the tube amp and then listen again.

 

[svtcontour]

No it just means a lot of unused power is wasted.


Coloration can be signal dependent.
The amount of harmonics that reach audible levels is level dependent.
Roll-off (lows and highs) is certainly output level dependent.


You said EDM would not play loud enough for you which means you are already exceeding the rated output power of the amp.

Oh not quite what i said. So EDM is fine, its just if I want to play it very loud, its not going to get there. For example If I want to turn it up to the point where the bass is hitting over 105db on peaks this tube amp will run out of steam but even at high 90's its composed. So it was my way to say that it cannot replace my bigger SS amp for those situations.

 

[svtcontour]

if you google oldchen el34 or laochen el34 you'll find everything you need to know

its a 15w SET with the optional obligatory bluetooth hooked onto the side

for $200 its a not a bad idea to dip your toe into tubes

Actually where I purchased from it was listed as 10wpc and mine was the model without BT (I didnt want the extra stuff in it). I read online that most of the chinese amps are overrated on power and some are saying 6-7wpc is probably more reasonable at low distortion levels. Wish someone had tested one

 

[svtcontour]

This!

@svtcontour : you can add a power resistor of a few Ohm in series between the output of the solid state amp and the speaker to emulate the output resistance of the tube amp and then listen again.

Oh interesting. So say something like 2-4 ohms? I may have 10W resistors of those values.

 

[voodooless]

You said EDM would not play loud enough for you which means you are already exceeding the rated output power of the amp.

That’s not very surprising. There is no way the bass section of the open baffle is 97 dB efficient. You’ll need a lot of power down there to fight the roll off.

 

[svtcontour]

That’s not very surprising. There is no way the bass section of the open baffle is 97 dB efficient. You’ll need a lot of power down there to fight the roll off.

They are pretty big OB's with a pair of 15" PA drivers which are fairly sensitive but you're probably right. I was looking at approx average across the board but probably below about 60Hz its definitely on the way down but speaker response at 1m is a few posts above.