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Chinese Tube Amp?

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Sal Brisindi

Sal Brisindi

Member
Joined 2006
tuberadios.com
Here are the specs on the 6550 with the type of amp I want to build and a couple of applications. The curves for the tube I found online is attached.

Thank You,
Sal

*******************************************************
NJ7P Tube Database Search
6550
Power Pentode

Base & Bulb ( RCA RC-29 - 1975)
EIA Base 7S

Application

Glass octal type used in the output stages of high-fidelity audio amplifiers. Requires octal socket.
Mechanical Data

Pentode
Input ......................................... 14 pf
Output ........................................ 12 pf
Grid to Plate ................................. 0.85 pf
Maximum Ratings (Design Center Values)

Pentode
Plate Voltage ................................. 600 V
Grid No. 2 Voltage ............................ 400 V
Plate Dissipation ............................. 35 W
Characteristics and Typical Operation


Push Pull Class A Amplifier
Plate Voltage ................................. 400 V
Grid No. 2 Voltage ............................ 275 V
Grid No. 1 Voltage ............................ -25 V
Plate Current (Zero Signal) ................... 180 mA
Plate Current (Maximum Signal) ................ 270 mA
Grid No. 2 Current (Zero Signal) .............. 9 mA
Grid No. 2 Current (Maximum Signal) ........... 44 mA
Load Resistance ............................... 3500 ?
Power Output (approx) ......................... 55 W
Characteristics and Typical Operation

Push Pull Class A Amplifier
Plate Voltage ................................. 400 V
Grid No. 2 Voltage ............................ 300 V
Grid No. 1 Voltage Derived from
Cathode Bias Resistor ....................... 140 ?
Plate Current (Zero Signal) ................... 166 mA
Plate Current (Maximum Signal) ................ 190 mA
Grid No. 2 Current (Zero Signal) .............. 7.5 mA
Grid No. 2 Current (Maximum Signal) ........... 39 mA
Load Resistance ............................... 4500 ?
Power Output (approx) ......................... 41 W
Characteristics and Typical Operation

Push Pull Class A Amplifier (Triode Connected)
Plate Voltage ................................. 450 V
Grid No. 2 Voltage ............................ 450 V
Grid No. 1 Voltage ............................ -46 V
Plate Current (Zero Signal) ................... 150 mA
Plate Current (Maximum Signal) ................ 220 mA
Load Resistance ............................... 4000 ?
Power Output (approx) ......................... 28 W
Total Harmonic Distortion ..................... 2.5 %
Characteristics and Typical Operation

Push Pull Class AB1 Amplifier
Plate Voltage ................................. 400 V
Grid No. 2 Voltage ............................ 275 V
Grid No. 1 Voltage ............................ -23 V
Peak Grid No. 1 Voltage........................ 17 V
Plate Current (Zero Signal) ................... 180 mA
Plate Current (Maximum Signal) ................ 270 mA
Grid No. 2 Current (Zero Signal) .............. 9 mA
Grid No. 2 Current (Maximum Signal) ........... 44 mA
Load Resistance ............................... 3500 ?
Power Output (approx) ......................... 55 W
Total Harmonic Distortion ..................... 3 %
Characteristics and Typical Operation
*****************************************************
 

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E

ErikdeBest

Member
Joined 2003
Olá BSGD

You can have a look at the work done by Ricardo, here is a picture of one of his amps. http://www.diyaudio.com/forums/showthread.php?postid=1185789#post1185789

They fit your need for power, seem to perform quite well, reliable and the stuff. But they will cost you somewhat more than a cheap chinese though. Still cheaper than an Audiopax, I imagine...

Good luck in tubeland, Erik

I am a brazilian, and know Ricardo from a yahoo discussiongroup called justtubes.
 
bsgd

bsgd

Member
Joined 2008
regenceaudio.com
Richard Ellis said:
Bernardo:
Hi........Just down south of you here in Argentina, I am still trying to find a transformer manufacturer in country that will make a 'special order' for me...I have designed an 813 Single ended amp but the transformers would be imported....as my wife (Argentinian born) points out to me, the importing of said transformers will drive the price way out of reason.
That said, when we came here we brought our appliances which were 220VAC but the distribution was different requiring a large transformer for our clothes dryer. The KEY was this transformer was a custom made 220VAC-220VAC isolation type with a center tap on the secondary. This transformer is Appx 200 mm high, 300mm wide,300mm deep...at 20? Kilos'.
It was 'made' for appx. 1200 Pesos. This monster is priced just fine considering the Peso to dollar conversion rate!
This great pricing is what got me to consider building tube amps in the first place. Look up www.kaizenelectronica.com.ar they won't respond to my E-mails....perhaps we can work together to find suitable LOCAL manufacturers.
_______________________________________Rick...........
Click to expand...

Well I know some guys here in Brazil that can make custom winded transformers. The company is called "PULSAR" and they really do a great job.
Unfortunately, as you know, custom duties in latin america are ridiculously high, so we often cannot go on with our projects, since we cannot get the parts. It would be great if we could find a way to get this parts somewhere at an acceptable price.
 
bsgd

bsgd

Member
Joined 2008
regenceaudio.com
ErikdeBest said:
Olá BSGD

You can have a look at the work done by Ricardo, here is a picture of one of his amps. http://www.diyaudio.com/forums/showthread.php?postid=1185789#post1185789

They fit your need for power, seem to perform quite well, reliable and the stuff. But they will cost you somewhat more than a cheap chinese though. Still cheaper than an Audiopax, I imagine...

Good luck in tubeland, Erik

I am a brazilian, and know Ricardo from a yahoo discussiongroup called justtubes.
Click to expand...


Thank you very much Erik, I just sent Ricardo an e-mail.
BTW, do you know Ricardo's e-mail? Thanks.
 
Lowrider

Lowrider

Member
Joined 2007
melorib.com/hifi.html
Wavebourn

Wavebourn

Member
Joined 2006
wavebourn.com
pchw said:

Excellent, I have quite a few of these and don't know what to do with them. I am watching this thread closely from about 20 miles down south :)
Click to expand...


Sorry Fred, not today: I'm currently busy with my console, there have to be a concert tonight in my house. Diego Jameau is coming from Sebastopol; he is a dancer, composer, plays multiple instruments; tonight he is going to sing and play a guitar. I'm not sure if enough of guests will come to cover his fuel (suggested donations are $15), so probably he'll not come if enough of people don't RSVP, but anyway I have to prepare my equipment
(I'll post a picture of a hedgehog that's a strip from console, 2 channels). I decided to put my "Be-El-Countoiur" in this couple of channels (I did that a long time ago, when our bass guitarist liked to scream when wanted to sing aloud). And Cadmium was not restricted yet, so some more complex solutions have to be implemented to satisfy RoHS regulations...
 
Wavebourn

Wavebourn

Member
Joined 2006
wavebourn.com
pchw said:
Hi Anatoliy,

I didn't mean to see more today or any particular date :) We all have other obligation that must be fulfilled first ;) Only post the bits and pieces when you have free cycle. I hope the concert will be successful!!!

Cheers,
Click to expand...

Ok Fred, I'm ready to continue the project. I'll better start a new thread to distinguish my new design from current Chinese production. :clown:
 
Wavebourn

Wavebourn

Member
Joined 2006
wavebourn.com
pchw said:

Ditto, and I was about to suggest to start a new thread as well :)
Click to expand...


Ok, let me draw some sketch calculating on a napkin, bring some transformers from attic, breadboard and tweak, then I'll start the thread.

I think a "voltage" shoulder will contain tubes only, while a "current" shoulder will be made of a transistor and an opamp. However, the latest will develop some phase shifts on highs, but since it's output dynamic resistance will be high I don't expect it to be a big deal at all.

For an average current a triode shoulder will be a "leading" one, i.e. a current shoulder's idle current will be determined by a voltage drop in cathode of a triode one.
 
ChopperCharles

ChopperCharles

Member
Joined 2008
choppercharles.com
bsgd said:
Hi all!

This is my first post here. Few weeks ago I got a k-12m kit and I love it... only problem is that its pretty low on power.

So I was thinking of getting a relatively cheap chinese tube amp, and I'm looking for recomendations. I'm in Brazil, so getting a used Dyna or something is not a good option, since custom duties here are very, very high (96%).


So, can anyone recommend me a good chinese tube amp and where can I order it??

Thank you very much!

Bernardo.
Click to expand...

Bernado, there's been a lot of off-topic discussion, so but I'm replying to your original post. If you think the K-12M kit is low on power, you might be better off investing your money in some high efficiency speakers. I picked up a pair of Cerwin Vega VS-150 speakers off of craigslist locally for $200... they're rated efficiency is 102dB... a potato could drive these to insane volume levels. They're huge though!!

But if you really want to upgrade to a quality Chinese amplifier, I really recommend the Yaqin MC-100B amplifier. I bought it off of eBay from Canadian Hi Fi Online. Every amp comes with a 1 year full replacement warranty plus a 3 year labor warranty (you just pay for parts). KT88 output tubes, 30 watts triode / 60 watts ultralinear, for $800 shipped to your door. Canadian hi fi inspects, tests, and sets the bias on each amp they sell, so no surprises.

I don't work for them or anything... I'm just a really satisfied customer.

Charles.
 
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