Cheap & Well Made Chinese SE EL34 Amp - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 12th August 2011, 03:43 AM   #1
ttan98 is offline ttan98  Australia
diyAudio Member
 
Join Date: Apr 2006
Location: Melb
Default Cheap & Well Made Chinese SE EL34 Amp

Hi,

I like share with all of you the Single Ended amp I bought recently and it arrives today. I have not powered it up as yet. Take a look at the images here.

I paid US$200 plus $100 postage by airmail. I think it is a bargain. All the parts alone will exceed $200.

As you can see the chassis is very well made, chromium plated both top and bottom plate covers. The components are mounted on PCB and finish is very good as well. The rear view, you can see a black button it selects between the 2 inputs.

It does not come with a manual but the seller will provide you with a circuit diagram. The circuit is pretty standard, no feedback the driver is 6N3 connected in parallel to drive the EL34 which is connected in UL mode. It claims to give 12 watts I guess more like 10watts.

My intention is listen to it for a while and then modify it to accommodate KT88 tubes which I have few lying around.

You can see better quality images here,
Flickr: ttan98's Photostream
Attached Images
File Type: jpg P8123871V1.jpg (89.3 KB, 918 views)
File Type: jpg P8123872V1.jpg (81.7 KB, 869 views)
File Type: jpg P8123877V1.jpg (68.0 KB, 865 views)
  Reply With Quote
Old 12th August 2011, 03:56 AM   #2
diyAudio Member
 
Mr. Zenith's Avatar
 
Join Date: Aug 2009
Location: Central NC
It would be interesting to see the schematic. Are the output transformers actually potted or are those just covers? Seems a nice find at any rate. Let us know how the future mods work out.

The name "TUBE" vacuum tube amplifier reminds me of the fad for generic products here in the states during the early '80's. They came in plain white packaging with the name of the item in bold black letters, along with the even-then-ubiquitous UPC codes. "SALTINES", "CIGARETTES" and "BEER" immediately spring to mind...
  Reply With Quote
Old 12th August 2011, 04:49 AM   #3
diyAudio Member
 
HollowState's Avatar
 
Join Date: Aug 2006
Location: Taxland, New Jersey
Quote:
Originally Posted by ttan98 View Post
My intention is listen to it for a while and then modify it to accommodate KT88 tubes which I have few lying around.
Trying to adapt KT88s to this amplifier will not be very fruitful. Even if your power transformer has the extra filament current necessary, you will find that to make them perform well you'll need higher bias voltage and higher B+ voltage as well. Without that you'll still only get about the same wattage output. Power out is proportional to power in. Also, the output transformer primary impedance will not be the best match. This is assuming the Chicoms designed it right for EL34s. KT88s may look prettier, but that's about all you'll gain. Maybe a "difference" in sound. Sorry if I'm a party pooper.
__________________
"It is hard to imagine a more stupid or more dangerous way of making decisions than by putting those decisions in the hands of people who pay no price for being wrong." ~Thomas Sowell
  Reply With Quote
Old 12th August 2011, 05:24 AM   #4
ttan98 is offline ttan98  Australia
diyAudio Member
 
Join Date: Apr 2006
Location: Melb
Quote:
Originally Posted by HollowState View Post
Trying to adapt KT88s to this amplifier will not be very fruitful. Even if your power transformer has the extra filament current necessary, you will find that to make them perform well you'll need higher bias voltage and higher B+ voltage as well. Without that you'll still only get about the same wattage output. Power out is proportional to power in. Also, the output transformer primary impedance will not be the best match. This is assuming the Chicoms designed it right for EL34s. KT88s may look prettier, but that's about all you'll gain. Maybe a "difference" in sound. Sorry if I'm a party pooper.
Most o/p transformer will work well with EL34, even if I bias KT88 at lower current it should work well. A 3.5K or 5K transformer will work.
  Reply With Quote
Old 12th August 2011, 05:28 AM   #5
ttan98 is offline ttan98  Australia
diyAudio Member
 
Join Date: Apr 2006
Location: Melb
Hi,

I powered it up and it worked fine, very quiet and no hum.

I cannot release the circuit without the supplier approval, it is quite straight forward very similar to this,

DIY Single-Ended KT88 / 6L6 / EL34 / 6CA7 Tube Amplifier

except the 6N3 twin triode is connected in parallel to give more current.
  Reply With Quote
Old 15th January 2012, 05:46 PM   #6
diyAudio Member
 
Join Date: Aug 2010
Location: Paris
Hi,

I just finised building the exact same amp I got as a kit for christmas (only difference is no PCB).
I replaced the 6N2J with 12AX7.
The amp is driving a pair of wharfedale 10.1( sensitivity rated 86Db).
Sound is good and no hum. Of course less power that with the gainclone LM3886 I had before.
One thing I have to say is that the power transformer is sizzling.
I tied the nuts holding it but no luck.
Do you experience the same?
Maybe the transformer is a little bit underdimentioned!

Alex
  Reply With Quote
Old 15th January 2012, 08:20 PM   #7
diyAudio Member
 
Join Date: Aug 2005
How much power supply filtering is there? Just those teeny caps?
  Reply With Quote
Old 15th January 2012, 08:26 PM   #8
diyAudio Member
 
Join Date: Aug 2010
Location: Paris
here is the schematic :
Click the image to open in full size.
  Reply With Quote
Old 15th January 2012, 10:00 PM   #9
diyAudio Member
 
Alain Poitras's Avatar
 
Join Date: Aug 2011
Location: Laurentides QC
Blog Entries: 1
Very nice look and 6CA7/EL34 is a very good tube. I don't know about the output transformer quality but 200$ + 100$ shipping is a cheap price.
  Reply With Quote
Old 16th January 2012, 07:35 AM   #10
diyAudio Member
 
Join Date: Aug 2010
Location: Paris
OK, fixed the sizzling problem by tying more the bolds, all good now!

Now I have to listen to it for a while and see if I retube with better quality 12AX7s

Alex
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Suppo Audio -- New Chinese EL84 PP amp for CHEAP. bigjppop Tubes / Valves 431 7th February 2013 10:30 PM
Building something better with a Chinese SE EL34B Amp DIY Kit VictoriaGuy Tubes / Valves 19 28th June 2011 07:52 AM
Chinese EL34 amp to modify Cobra2 Tubes / Valves 53 10th April 2009 04:32 PM
cheap Chinese amp modules on ebay . Anyone know what they are ? jives11 Chip Amps 36 28th November 2008 04:35 PM
Cheap and Chinese KT88 SE amp andrew_whitham Tubes / Valves 46 19th May 2007 11:05 AM


New To Site? Need Help?

All times are GMT. The time now is 10:06 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2