Chinese EL34 Tube amp with Omegas

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tdogzthmn

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Chinese EL34 Tube amp with Omegas
« on: 26 Apr 2019, 05:19 am »
For the past few months I had been powering my Junior 8 XRS with a Bottlehead SEX amp which puts out around 1.5 watts.  Overall its a great sounding amp with efficient speakers and headphones.  However replacement tubes for the amp have become scarce and there are limited tube rolling opportunities so I started looking into other more available tube types.

One of the more commonly available is the EL34 and its substitutes.  In particular I liked this tube because it is in current production by several tube makers so the supply or replacements is ample.

While looking for used EL34 amps on ebay I came across several Chinese made offerings from Nobsound and Douk Audio.  In particular the EL34 amp made under the JHB Tube brand caught my eye and seemed to be very affordable at $200 + shipping.  There were no reviews I could find but there was a return policy so I gave it a shot.

The amp shipped quickly and I was up and running within a week.  I hooked it all up threw the switch and no smoke!  The amp was nice and quiet with no buzz or hum and minimal hiss at full volume.

Sonically I have been very pleased with the amplifier.  At 8 watts I only need the volume less than a quarter turn for normal listening levels in my space.  The tone so far seems mostly neutral with nice detail and soundstage that goes wider than the speakers.  The amp has fewer than 10 hours and I will be on the lookout for how things sound once the amp settles in.  With no glaring issues to start with I expect this amp will continue to improve with use.

Might be a nice way for someone wanting to get into tube amps to get something that does the job on a budget. 





jmolsberg

Re: Chinese EL34 Tube amp with Omegas
« Reply #1 on: 26 Apr 2019, 04:57 pm »
Sounds like you picked a winner! Good looking setup to boot. Listen in good health

Gdub

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Re: Chinese EL34 Tube amp with Omegas
« Reply #2 on: 26 Apr 2019, 05:16 pm »
I am interested to know how this sounds after it settles in a little longer. I am looking for an inexpensive tube amp for a second listening room to pair with a set of omega monitors.

mick wolfe

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Re: Chinese EL34 Tube amp with Omegas
« Reply #3 on: 27 Apr 2019, 05:34 pm »
Depending on your budget and overall needs,  the Kingko KA101 integrated is supposedly a perfect match for Omega's. Looks a lot more serious than the lower priced Chinese options, but then again it comes in a shade under $900. There are a few rave reviews out there on the KA101 though.

sophie999

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Re: Chinese EL34 Tube amp with Omegas
« Reply #4 on: 27 Apr 2019, 05:42 pm »
At similar price point, you can also get Frenzel amp (just under 1K), 100% US made, not many but generally very positive reviews. More power too.
Check it out: https://www.frenzeltubeamps.com

sunnydaze

Re: Chinese EL34 Tube amp with Omegas
« Reply #5 on: 27 Apr 2019, 08:46 pm »
Thanks for the heads-up on the Kingko amp.

Unfamiliar to me, but it does look interesting.     :thumb:

Canada Rob

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Re: Chinese EL34 Tube amp with Omegas
« Reply #6 on: 27 Apr 2019, 11:48 pm »
Nice amp (and system) tdogzthmn.  $200 plus shipping looks like a great deal.  Hope it works out well for you.

Here's a very affordable single ended amp made in Canada just a few hours from where I live.
http://www.thebestamp.com/Single-Ended_Tube_Amps/SE-6BQ5.php

SET Man

Re: Chinese EL34 Tube amp with Omegas
« Reply #7 on: 28 Apr 2019, 01:33 am »
For the past few months I had been powering my Junior 8 XRS with a Bottlehead SEX amp which puts out around 1.5 watts.  Overall its a great sounding amp with efficient speakers and headphones.  However replacement tubes for the amp have become scarce and there are limited tube rolling opportunities so I started looking into other more available tube types.
....

Hey!

    Yeah, Bottlehead SEX is one of amp that really popularized the use of 6EM7 and similar tubes. Unfortunately my SET am also use 6EM7 and I've watching the price of these of these tubes going up in recent years.  :evil:

    Anyway, if anyone here have a stash of 6EM7 tubes lying around and want to get rid of let me know. :icon_lol:

...

While looking for used EL34 amps on ebay I came across several Chinese made offerings from Nobsound and Douk Audio.  In particular the EL34 amp made under the JHB Tube brand caught my eye and seemed to be very affordable at $200 + shipping.  There were no reviews I could find but there was a return policy so I gave it a shot.

...

    I've seen many Chinese made tube amps on places like eBay. I have admit that even though I know that labor cost is a lot less over there compare to the labor cost here in the US. I mean, what $300USD total with shipping? Still I have to scratch my head of how do they made that so cheap!  :scratch: It is a bit of a risk I would say even with a good return policy shipping it back from US will cost a lot of money.

   Anyway, I wonder how is the quality of the output transformers are? Copper purity, winding tolerance and etc? Beside that I'm interested in how reliable this amp is. Please keep us posted on this.

   Also, a little side note... SET circuitry is very simple. You can tinker with it a bit. A simple way and this can have a big impact in sound is try some coupling caps. Of course if you don't like it you can always put the original caps back in. If you assembled the Bottlehead SEX yourself this should be easy for you :wink:

Buddy

tdogzthmn

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Re: Chinese EL34 Tube amp with Omegas
« Reply #8 on: 28 Apr 2019, 06:00 am »
Here's some shots of the interior which I briefly inspected before I first turned on the amp.

I do have some soldering skills but I would not be sure which parts if any are worth upgrading.











FullRangeMan

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Re: Chinese EL34 Tube amp with Omegas
« Reply #9 on: 28 Apr 2019, 09:07 am »
Nice layout, I would use this amp some 5-10 years with these parts and when these parts get old I could change something.

FullRangeMan

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Re: Chinese EL34 Tube amp with Omegas
« Reply #10 on: 28 Apr 2019, 09:14 am »
Nice amp (and system) tdogzthmn.  $200 plus shipping looks like a great deal.  Hope it works out well for you.

Here's a very affordable single ended amp made in Canada just a few hours from where I live.
http://www.thebestamp.com/Single-Ended_Tube_Amps/SE-6BQ5.php
Great looking amps!  :thumb:

tdogzthmn

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Re: Chinese EL34 Tube amp with Omegas
« Reply #11 on: 28 Apr 2019, 05:11 pm »
So far my only criticism is the case could use some more structural support.  I notice some sag along the horizontal axis due to the weight of the transformers. This can likely be easily addressed by building some supports myself so I'm not too concerned.

tdogzthmn

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Re: Chinese EL34 Tube amp with Omegas
« Reply #12 on: 28 Apr 2019, 05:22 pm »
Great looking amps!  :thumb:

Thanks for the appreciation.

I finally got it all interconnected using the Sansui AU-517 as a receiver for all my sources. 

Its been fun to compare my tube driven Fullrange speakers with my DSP corrected Active Monitors.  I find both are very compelling approaches in their own ways and its nice to have them available at the same time for A/B listening comparisons. 

mick wolfe

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Re: Chinese EL34 Tube amp with Omegas
« Reply #13 on: 28 Apr 2019, 05:56 pm »
Thanks for the heads-up on the Kingko amp.

Unfamiliar to me, but it does look interesting.     :thumb:

First off, the KA-101 is a EL 84 based integrated. I believe the OP was seeking an EL 34 based unit. So my bad on that one. That being said, the KA-101 gets a stellar review from Richard Austen over at Dagogo. He replaced his former LM 219ia ($7500 ) with the KA-101. This partially because the 219 is a 125 lb. beast that's difficult to transport. That said, the  KingKo more than held its own sonically when using fairly efficient Audio Note speakers.

SET Man

Re: Chinese EL34 Tube amp with Omegas
« Reply #14 on: 28 Apr 2019, 11:32 pm »
Here's some shots of the interior which I briefly inspected before I first turned on the amp.

I do have some soldering skills but I would not be sure which parts if any are worth upgrading.







Hey!

   Is that a blood stain inside the chassis?  :o Just kidding, I know it is glue  :lol:

   That's not bad at all inside! The labor cost of assembling and soldering this amp by hands here in the US alone will likely be more than the cost of this amp. Well, they have to cut corner somewhere, like thinner chassis, AC heater and plastic ziptie holding cap to the chassis.

   As for coupling caps. Likely those 2 yellow caps, and probably have value of 0.22uf or 0.47uf. You can play around with these to fine tune the sound. I have Jensen copper foil PIO in my amps and in line-stage of my pre-amp. If you want some cheap PIO caps to play with first, you can find Russian K40-9 PIO caps on places like eBay and etc. Although, I don't have this in my system as coupling caps but I'm using a pair of 0.1uf as bypass cap in my DAC output.

  Anyway, if you're going to play around with caps just make sure they are the same value and same or higher voltage in what in there right now.

Buddy

Wig

Re: Chinese EL34 Tube amp with Omegas
« Reply #15 on: 29 Apr 2019, 02:36 am »
At that price point, I might just jump on one of these for my bookshelf speakers. 😁

Canada Rob

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Re: Chinese EL34 Tube amp with Omegas
« Reply #16 on: 29 Apr 2019, 05:15 pm »
Nice layout.  I like the fact it's point to point wiring with chassis mounted tube sockets.  The solder joints don't look so good though, at least from what I can see in the bottom picture. 

If you're playing with caps, make sure they're fully discharged before doing anything.  :o

bladesmith

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Re: Chinese EL34 Tube amp with Omegas
« Reply #17 on: 29 Apr 2019, 05:20 pm »
Nice layout.  I like the fact it's point to point wiring with chassis mounted tube sockets.  The solder joints don't look so good though, at least from what I can see in the bottom picture. 

If you're playing with caps, make sure they're fully discharged before doing anything.  :o

Agreed...  but, could easily be remedied..

doggie

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Re: Chinese EL34 Tube amp with Omegas
« Reply #18 on: 2 May 2019, 12:34 pm »
Here's some shots of the interior which I briefly inspected before I first turned on the amp.

I do have some soldering skills but I would not be sure which parts if any are worth upgrading.


The easiest upgrade will be to replace the input tube with a nice NOS one. An American 6SL7 would an equivalent. Lots of good choices for that.

You could also replace any coupling caps in the signal path with some high quality ones. See if you can get a circuit diagram from the seller.



tdogzthmn

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Re: Chinese EL34 Tube amp with Omegas
« Reply #19 on: 9 May 2019, 05:03 am »
Its been about two weeks of intermittent use and the amp has been breaking in nicely!

I've upgraded the suite of tubes to JJ versions and currently running KT77 in the power tube position.  These tubes are brand new but they really do seem to bring out the treble extension where the JJ EL34 II previously has sounds more mid forward. 

The 8 watts per channel leave me with plenty of headroom and typically less than a quarter turn gets me to normal listening levels.  I plan to give it a few more weeks of use before swapping back to the Bottlehead SEX for comparison.  Still pleased overall and I'm looking forward to trying out more tubes to figure out which yields the best results!