power output of EL34

[hschaser]

Hi All,

I am intending to get a kit el34 intergrated amplifier for diy.
With 6SL7 as the pre section.
Need to know how can i have better/greater power output than 13w per channel max as spec.? As i see from spec sheet EL34 can output greater power than 13w. Have it got to do with the power transformers and outputtransformer?
Thanks

 

[Tesla88]

Any link to the kit you watching?

As long as we don't know circuit topology and class of operation , it's impossible to say...

Are we talking about 1 EL34 or pair ? With only one EL34 per channel you have a SE class A amp with 8W typ. sine power .

With a pair of EL34 you can get more power in push pull , but again , output power vary with plate voltage , primary impedance of Output transformer , Class of operation A - Ab1 - Ab2 and output stage connection Pentode - UL - Triode.

For ex. a push pull , triode connected , class A would give about 15W . . .

 

[jazbo8]

Since the max Pda for the EL34 is only 25W, the 13W output figure (which seems to suggest that it is SE) already exceeds the maximum possible Class A efficiency of 50%, in a real circuit, that figure is going to be lower, so in other words, the 13W rating is already an exaggeration - you may want to ask the seller, what is the distortion at 13W or how long is the expected tube life?!

 

[freddi]

http://frank.pocnet.net/sheets/129/e/EL34.pdf

 

[hschaser]

Yes the configuration is for a SE amplification with a distortion level of less than 1% as stated by the seller. K will try to get korre details and post it uphere. Thanks for the help.

 

[hschaser]

Hi, attached are the kit details and schematics

Features and spec:

Simple electronic circuit,Ultra linear amplification circuit
Automatic bias
Using 5H choking coil to filtering
5Z3P tube rectifier
6N9P preamplifier
EL34-B power amplifier
Max Output Power 13W X 2
Load: 4Ohm or 8Ohm
Harmonic distortion: =<1%
SNR: >= 89dB
Input sensitivity: 600mV - 1V
Input impedance: 100KΩ (stereo input)
Frequency response: 20Hz - 26KHz
THD: =<0.5% (1KHz)
Silkscreen stainless steel

Recommend minimum configuration:

Bass woofer size : 6.5'' inch
Sensitivity: >= 90db (very important )

An externally hosted image should be here but it was not working when we last tested it.

 

[Malcolm Irving]

To avoid confusion, it isn't really an ultra-linear circuit. The person who wrote the spec. probably just meant 'very linear circuit'.

 

[hschaser]

Any help will be much appreciated.

 

[hschaser]

Thanks Malcolm for your clarification

 

[jazbo8]

As mentioned, the schematic does not show an UL connection, and using the figures provided above, the output power is a lot less than the 13W spec'd... 15/300 = 0.05, Po = 0.05^2*3500 = 8.75W even asssuming zero winding loss in the output transformer.

 

[hschaser]

jazbo8, wow you are real quick with figures... any suggestion or ways to overcome the limitations? i.e using better parts and tranny?

 

[jazbo8]

Yes, it could be done but then it defeats the whole purpose of getting the kit. I would recommend that you find another kit or build a proven design - there are many that have been posted on this forum.

 

[hschaser]

jazbo8... thanks..for your excellent idea.... will look for them..
I came across this a PP6L6GC amp which I think I can handle.... it is called the Oddwatt225. any commends?

 

[hschaser]

the link is :6SL7 SRPP / KT77 Push-Pull Class-A Ultra-Linear DIY Tube Amplifier

 

[jazbo8]

That's an interesting design - Class A only, so better crank the air-cond to full blast ;-)

 

[hschaser]

Any good PP AB1 design which you think can point me to?

 

[jazbo8]

There are so many, but Eli Duttman's El Cheapo, gingertube's Baby Huey and Gary Pimm's Tabor comes to mind, the designers all are regular contributors to the forum and many have built the amps, so you will get good support here. Have fun reading through the threads.

 

[hschaser]

Thanks

 

[mark02131]

THis is my favorite EL34 Amplifier design. It's on my list of builds, It's a nice 30 watt design based on the old Mullard Circuit but brought up to date. If your looking for a little more power.

30W Push Pull amplifier designed by Claus Byrith, Royal Academy of Music in Aarhus, Denmark. | Lundahl Transformers

 

[LAZAROIU]

As mentioned, the schematic does not show an UL connection, and using the figures provided above, the output power is a lot less than the 13W spec'd... 15/300 = 0.05, Po = 0.05^2*3500 = 8.75W even asssuming zero winding loss in the output transformer.

Corect! Configuration is good, but the results are not true.
After drawing the diagram can not get those performances.
After we made a simulation, results are different and will be very close to reality, in my opinion!