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Old 17th February 2012, 02:29 PM   #1
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Default Choosing Btw 2 EL34 China Tube Amps

Hi.
This is my first post here.
I'm a complete nob in Tube Amps.
Would appreciate advises and comments on which amp to choose based on the following amp spec.

I listen to :
Mainly Vocals
Some Classical
My Room is only 4m x 5m
I don't blast my speakers. Listening volume considered moderate.

My Speaker (Wharfedale Diamond 10.1 Bookshelf) :
Bass/Mid Driver - 125mm
Tweeter - 25mm
Nominal Impedance - 6 Ω
A/V Shielded - yes
Sensitivity (1W @ 1M) 86 dB
Nominal Frequency Range - 48-24kHz
HF Limit (-10dB) - 44kHz
Freq. Fb - 50Hz
Crossover Frequency - 1.8kHz

<Tube Amp A>
Output Power - 35 watts x 2 in Class A Push and Pull circuit design
Output Tube - EL-34x 4
Frequency - 10Hz-70KHz +/-3 dB
Driver Tube - 6N2 x 2
Signal/Noise Ratio - 90dB
Distortion - Less than 1% at full power
Input Consumption - < 100w
Ohms - 4 ohms and 8 ohms
Input Jack - 2 groups
Click the image to open in full size.

<Tube Amp B>
Output Power - 12 watts x 2
Output Tube - EL-34x 2
Frequency - 20Hz-28KHz
Driver Tube - 6N2J x 2
??? Tube - 5Z4PJ x 1
Signal/Noise Ratio - 88dB
Ohms - 4 ohms and 8 ohms
Click the image to open in full size.

I really don't know what these specs mean. But from the numbers, am I correct to say that Tube Amp A is of a better spec?
Tube Amp B has an additional Tube - 5Z4PJ compared to Tube Amp A. Does this tube has any advantage over one which doesn't?

Thank you.
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Old 17th February 2012, 04:04 PM   #2
DF96 is offline DF96  England
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The main difference between those two amps is that the first is push-pull (PP) and the second is single-ended (SE). Some people will tell you that PP is better, others prefer SE. If I said that it is a matter of taste, some people would disagree with that and claim that one is intrinsically 'better' than the other. Its a bit like cars: some people love French cars, others hate them. Both can offer reasons why, which they sincerely believe to be true.

The SE amp has a valve (5Z4) acting a rectifier (assuming that it is not just there for cosmetic reasons - you have to be careful with the Chinese!). The PP amp will have silicon rectifiers. Again, people differ on how (if at all) this affects sound quality.

It's a bit like asking a group of drinkers whether beer or wine is better. Each can give you their own answer, but none can tell you which you will prefer. They may try to tell you which you should prefer - the same as them!

I suggest you do some more snooping around the internet, including this forum, and pick up the chatter about these matters. Find friends who have PP or SE and listen to their systems, but bearing in mind that rooms and speakers can have a greater effect on sound than amplifiers.
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Old 17th February 2012, 07:42 PM   #3
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Location: Canada
Small room, no hard rock, half decent speakers, and low volume.

I'd go with a SE setup with all that I have heard people talk about. Something about the distortion and musicality that the single ended tube amps have over the PP amps. If you like listening to music then you go single ended. If you like listening to loud sound, then go push pull.

I am not sure if I buy fully into that as a compelling argument. I have heard both SE and PP and I think both have thief rightful place in making sound amplified. From a design standpoint, I like the SE circuit since it looks so simple and has such a short path from source to speaker.

Ever thought of building you own?
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Old 17th February 2012, 07:59 PM   #4
GloBug is offline GloBug  Canada
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Yes build your own or restore a local one, if not you'll likely be back on here asking for help with your Chinese amp. Hint.

These amps are made to "look" good enough to get them shipped, then your on your own.

If you must go that route, do some searching on here and find out which ones are the "good" ones, if there is such a thing.

That old saying holds true......unless you get lucky at a garage sale then you get more then you paid for.

Either way, Welcome and have fun.
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Old 17th February 2012, 08:12 PM   #5
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Quote:
Originally Posted by GloBug View Post
Yes build your own or restore a local one, if not you'll likely be back on here asking for help with your Chinese amp. Hint.

These amps are made to "look" good enough to get them shipped, then your on your own.

If you must go that route, do some searching on here and find out which ones are the "good" ones, if there is such a thing.

That old saying holds true......unless you get lucky at a garage sale then you get more then you paid for.

Either way, Welcome and have fun.
Well, I am glad you said it.

Anyway, vacuume5, you might want to do a quick search all the threads here about undersized transformers, faulty caps, unbalanced voltages, poorly done traces on PCBs, substandard soldering jobs, and the fixes that people needed to do to make the Chinese amps work "properly".

You might be better off with something made over here or by some reputable seller known on the forums.

With those two amps, you could do worse, but you could definitely do better. See what Siliconray has to offer, he posts here all the time, answers questions, gives insight to his products (might not be an engineer, but next best), and some of his stuff is reasonable priced.

I will be building the updated version of Mikael Abdellah's KT88 SE Tube Amplifier which can run SE or Ultralinear modes using KT88, KT77, 6550, EL34, and 6L6 tubes. Do a google search and you will see the plans. Again, reasonable priced.

If you want PP, then the other amp I will be building is the Bob Latino ST-70 (google it). All parts are there. All as a kit or sent all done for you. Again, reasonable priced.

And there is also a gentleman here who sells a whole KT88 SE kit as a kit or already done for you (can not recall his name, but check the swap area). Heard good things about him too. Again, reasonable priced for what you get.
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Old 17th February 2012, 11:45 PM   #6
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Quote:
Originally Posted by overtheairbroadcast View Post
And there is also a gentleman here who sells a whole KT88 SE kit as a kit or already done for you (can not recall his name, but check the swap area). Heard good things about him too. Again, reasonable priced for what you get.
Possibly this is the kit you are referring to in my sig?
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Old 18th February 2012, 01:54 AM   #7
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Quote:
Originally Posted by scitizen17 View Post
Possibly this is the kit you are referring to in my sig?
Why yes, that would be the one (the KT88 white one and the KT88 shiny one); I take it that your ears were burning.

I'm still very new to this place and I had seen your tube amp and it looked quite nice. That and some positive comments about it.

Nice to meet you.
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Old 18th February 2012, 02:04 AM   #8
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Quote:
Originally Posted by overtheairbroadcast View Post
Why yes, that would be the one (the KT88 white one and the KT88 shiny one); I take it that your ears were burning.

I'm still very new to this place and I had seen your tube amp and it looked quite nice. That and some positive comments about it.

Nice to meet you.
Likewise. I'm really reluctant to comment in a situation like this because of the "rules" but thought it would be OK in this case. Thanks for the recommendation. Welcome to the forum. This really is a great source of information not to mention help and advice from a great many fine engineers. Very few forums have the wealth of information that is available here.

Scott

Last edited by scott17; 18th February 2012 at 02:19 AM. Reason: engineering reference
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Old 18th February 2012, 02:34 AM   #9
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Location: Canada
Quote:
Originally Posted by vacuumes5 View Post
Hi.

I really don't know what these specs mean. But from the numbers, am I correct to say that Tube Amp A is of a better spec?
Tube Amp B has an additional Tube - 5Z4PJ compared to Tube Amp A. Does this tube has any advantage over one which doesn't?

Thank you.
vacuumes5, I mentioned a few kit manufacturers, a well laid out schematic, and providers and one of them (scitizen17/Scott) has appeared also. I neglected to mention the other SE vacuum tube kit vendor located here is Victor Kung in the Elekit forum. He was also one of the many contributors which made me want to join the forums here.

Well documented kits and with that part of the forum, anything problem with putting it together, troubleshooting, and modification has probably already been covered.

But back to where I started, ask the people who make the kits, read the forums, and then figure it out.

I do not think that I would chance the headache or potential problems with a Chinese tube amp. I used to live in China for three years with part of my job of running to Hong Kong now and then. I would also bring back, well more like mule back, a few tube amps in my many trips for friends. Either these amps would be well made in Hong Kong, Chinese made and then extensively modified for better sound by a professional, or one time -- very well made in Japan with new iron for the 220 voltage.

I have seen Chinese tube amps go ZAP and there would be no support or repair from the store where you purchased it from (this was in Shanghai, not some backwater). I found it sad back then that something as simple as supplying the correct schematics. I find it more saddening that this practice is still in effect to this day with all the advances in business practices and customer service. And I like China.

Just chose wisely.
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Old 26th February 2012, 08:30 AM   #10
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Thanks everyone for your valuable advises.
I'm not really those person who has the patience and expertise to build his own Tube Amp. I just started off with this new hobby and do not know how long my interest will last. Therefore, I do not want to spend too much of a fortune investing in a good Tube Amp. That's the reason I opted for the budget Chinese Tube Amp.
Not to mention, I've never listened to a tube Amp. How different will it sound compared to the normal Electronic Type Amps we can find in the big departmental stores.
Just want to spend a little bit first and see how it goes from here.
Like one of you mentioned, probably, I will encounter many issues with the Chinese Tubes when I get my hands on one.
Anyway, really appreciate your advises.
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