Got a Chinese tube amp and now world is upside down

[mhardy6647]

A 50Hz rated transformer can be used on both 50Hz AND 60Hz systems.
A 60Hz transformer can ONLY be used on 60Hz systems.

Thanks. I (clearly) was not clear on this!

Consider asking the manufacturer about the 110/120V thing.

He did say he's got a question in to... somebody.

I have a question in about the numbers.

 

[solderdude]

Judging from what's inside (assuming this is the same amp) then there is no point in opening up the amp to see if it can be set to a different voltage range as there seems to be only one primary coil (so 1 voltage). note the picture below is a screenshot, the link to the video it can from is here.

Changes are the transformer is for 115V-50/60 Hz and can be used on mains voltages from 110V to 120V.


Only the manufacturer can say for sure.

 

[mhardy6647]

Although, on the other hand , the innards of @Henry Lee's amp may or may not be identical to that one!
Heck -- were it mine... I'd take a peek.

 

[Henry Lee]

A 50Hz rated transformer can be used on both 50Hz AND 60Hz systems.
A 60Hz transformer can ONLY be used on 60Hz systems.

The only issue is the 110V vs 120V nominal.
The mains voltage may well be be between 110 and 125V, this can vary during the day and depends on your situation.

I would suggest to open up the amp and see if the mains transformer has taps or there is some way to configure it.
Alternatively keep using the inrush current limiter.

You don't need to worry much about overheating but running it on 10% over voltage (20% too much power) may shorten its lifespan.
A mains transformer is allowed/designed to work up to up to 200°F (93°C) but would recommend to measure it (let it run for several hours) to ensure it stays below 140°F (60°C)

Another (expensive) option is to use a regenerating UPS (so not the cheap ones !) and set the output to 110V.

Consider asking the manufacturer about the 110/120V thing and if it can be changed and/or is even necessary.

I have been checking the transformer temp and after several hours, it will run in the 120 degrees range.

I asked the seller (through Amazon) about the 110/120 issue. Here is the answer I received:

Hi Harry,That is a very thoughtful question. The short answer is: Yes, it is perfectly safe to run the 110V-configured amplifier on a standard US 120V mains supply.Here are a few technical details for your peace of mindesign Tolerance: Our power transformers are engineered with a safety margin that comfortably handles a +/- 10% voltage fluctuation. Running at 120V (which is about 9% higher than 110V) falls within this safe operating range.Performance Benefit: In many cases, a slightly higher plate voltage can actually provide a bit more dynamic headroom and a "snappier" sound, which many audiophiles prefer.Heat Management: As noted in the manual, higher voltage can lead to slightly increased operating temperatures. Please ensure the unit has at least 10cm (4 inches) of clearance from walls and that the top is never covered to maintain optimal ventilation.Since tube life is naturally affected by heat over time , we simply recommend that you do not leave the amplifier running unattended for extended periods.Please let us know if you have any other questions as you enjoy your new EL34 amp!Best Regards,Alice - Emoryseric Audio

Of course, that's what I wanted to hear. I have no idea whether I'm dealing with a person or AI.

The performance of the amp is beyond my expectations. I've spent a lot more money searching for something that sounds as good as my ST-70/PAS-3X with no luck. This time I may have made it. Swapping back and forth is unrealistic but the SET amp passes all the tests, including the big hit near the beginning of the Buddy Rich "Big Swing Face" and all my bass and and treble tracks: tight bass and sharp piano. Good cannons and bass drums at the end of the "1812 Overture". I can't say that it's better than my better SS gear, but it sounds good to me.

 

[mhardy6647]

"snappier" sound.

120 degrees (F) is quite reasonable.

 

[BlueTunes]

We should remember that as we approach the point of relatively perfect audio reproduction, the influence of the measurable disappears and the noise of the measurable gets louder.
Or in other words, once you solve the transmition problem, you are left with the reciever problem which is unsolvable.

Perhaps you just prefer the deviations from the baseline that analogue, valve amps provide.
Perhaps you can do that and also hold the notion that its not perfect

Perhaps it is ok for two things to be true at the same time.

In reality, this is the case regardless because what everyone fails to understand in music reporduction is that it can never be perfect.
The volume button stops it from being so.

Everything we listen to is based on personal preferences.

Enjoy the music

 

[solderdude]

I have been checking the transformer temp and after several hours, it will run in the 120 degrees range.

50oC is fine for a transformer.

I asked the seller (through Amazon) about the 110/120 issue. Here is the answer I received:

Hi Harry,That is a very thoughtful question. The short answer is: Yes, it is perfectly safe to run the 110V-configured amplifier on a standard US 120V mains supply.Here are a few technical details for your peace of mindesign Tolerance: Our power transformers are engineered with a safety margin that comfortably handles a +/- 10% voltage fluctuation. Running at 120V (which is about 9% higher than 110V) falls within this safe operating range.Performance Benefit: In many cases, a slightly higher plate voltage can actually provide a bit more dynamic headroom and a "snappier" sound, which many audiophiles prefer.Heat Management: As noted in the manual, higher voltage can lead to slightly increased operating temperatures. Please ensure the unit has at least 10cm (4 inches) of clearance from walls and that the top is never covered to maintain optimal ventilation.Since tube life is naturally affected by heat over time , we simply recommend that you do not leave the amplifier running unattended for extended periods.Please let us know if you have any other questions as you enjoy your new EL34 amp!Best Regards,Alice - Emoryseric Audio

Some of it is nonsense.
The 110-120V range is as expected (115V trafo)
The longevity of the tubes may be slightly shortened but usually emission becomes less before heaters give the ghost.

Of course, that's what I wanted to hear. I have no idea whether I'm dealing with a person or AI.

The performance of the amp is beyond my expectations. I've spent a lot more money searching for something that sounds as good as my ST-70/PAS-3X with no luck. This time I may have made it. Swapping back and forth is unrealistic but the SET amp passes all the tests, including the big hit near the beginning of the Buddy Rich "Big Swing Face" and all my bass and and treble tracks: tight bass and sharp piano. Good cannons and bass drums at the end of the "1812 Overture". I can't say that it's better than my better SS gear, but it sounds good to me.

When you are happy that's all that is needed.

It looks like you do not need to worry about the 120V rating.
When you were to measure the mains voltage during a day you may notice that it is never exactly 120V anyway.

 

[Henry Lee]

50oC is fine for a transformer.

Some of it is nonsense.
The 110-120V range is as expected (115V trafo)
The longevity of the tubes may be slightly shortened but usually emission becomes less before heaters give the ghost.


When you are happy that's all that is needed.

It looks like you do not need to worry about the 120V rating.
When you were to measure the mains voltage during a day you may notice that it is never exactly 120V anyway.

Last night 121.4. I'm through worrying about it.

 

[mhardy6647]

so am I
Should be good.
PS Glad you have electricity there in Watkinsville!

I guess Amazon didn't care or wasn't sure if we had electricity here in Watkinsville.

Let the record show: I did chortle when I read that in your earlier post!

Got a Chinese tube amp and now world is upside down

Is that a Panasonic 3700 DAT machine underneath? :) Hah good eye. Very close. SV-3800. I use it as my DAC. The tape portion was broken so my work was tossing it. I hooked it up via a USB to SPDIF adapter to the computer as my source is JRIVER) and it absolutely clobbered my Soncoz dual Sabre...

www.audiosciencereview.com

 

[RaymondFromThePyrénéés]

Hallo everybody.
After reading this experience and glowinthedarkaudio
I wonder why I should buy the wiim ultra for my futur open baffle Lii F15 ?
It seems that those small tube amps for 300
gives a much more pleasant sound than class D
(even if a class D might give a better reading on REW)
And perhaps I just buy a simple CD player ?

 

[mhardy6647]

Hallo everybody.
After reading this experience and glowinthedarkaudio
I wonder why I should buy the wiim ultra for my futur open baffle Lii F15 ?
It seems that those small tube amps for 300
gives a much more pleasant sound than class D...

Wait, you can tell it's better just by reading those two references?
Amazing.


Umm, yeah, no -- and, mind you, I am a fairly dedicated (if not dogmatic) vacuum tube amplifier user.
But not a cheap one. There are some things that cannot be done cheaply with quality in 2026. In this case, the important (cogent) example is (are) the output transformers.
The difference between good and cheap "iron" will be both measurable and audible.

 

[RaymondFromThePyrénéés]

Thank you. glowinthedarkaudio sound pretty convincing to me but I checked out the prices for his amps, they do not come cheap !!!

How much would according to your experience cost for a good vacuum tube amplifier ?


But I assume that you did not go there straight away,
I suppose that you worked your way up to the quality that you have today ?

Also, there are some people into DIY tube amps which will probably
lower the costs quite a bit, but I do not know whether that is difficult to learn ?

 

[Eulipian]

This is the little amp. View attachment 316490

If you decide you don't like it you can always repurpose it into a Marshal 18 watt.

 

[mhardy6647]

Thank you. glowinthedarkaudio sound pretty convincing to me but I checked out the prices for his amps, they do not come cheap !!!

How much would according to your experience cost for a good vacuum tube amplifier ?


But I assume that you did not go there straight away,
I suppose that you worked your way up to the quality that you have today ?

Also, there are some people into DIY tube amps which will probably
lower the costs quite a bit, but I do not know whether that is difficult to learn ?

Well... I grew up with vacuum tube amplifiers, so, yes and no.
I can also repair/restore and build them, and sometimes I do (more often the former). Vintage "iron" is excellent and relatively less expensive than good quality modern output transformers.

 

[RaymondFromThePyrénéés]

thank you. Building seems a bit complicated but what about Oilily's single ended amps ?

 

[RaymondFromThePyrénéés]

Wait, you can tell it's better just by reading those two references?
Amazing.


Umm, yeah, no -- and, mind you, I am a fairly dedicated (if not dogmatic) vacuum tube amplifier user.
But not a cheap one. There are some things that cannot be done cheaply with quality in 2026. In this case, the important (cogent) example is (are) the output transformers.
The difference between good and cheap "iron" will be both measurable and audible.

Dear M. Hardy.
I see someone selling a used Jolida JD707A for 750€ in my area.
Is that an amplifier you would recommend ?

 

[mhardy6647]

Dear M. Hardy.
I see someone selling a used Jolida JD707A for 750€ in my area.
Is that an amplifier you would recommend ?

Possibly. The JoLida name has been used by at least two different builders/companies. Have to see if that is the "real" company's product.

 

[RaymondFromThePyrénéés]

Just like Lii woofers.

Thank you, how to check ?

 

[mhardy6647]

I will look up the model when I have a chance. Otherwise, a web search should answer the question.

 

[mhardy6647]

Looks like it is from the original company. Push pull 6L6, looks reasonable.