• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

45 Type Push/Pull Amps

45 Type Push/Pull
How many here use or have heard one of these type amps?

So far I have used the 45 only in Single Ended but will build a PP amp with them some time.

What are the important factors here in this being able to produce quality sound of this tube with out the noise???

The same applies as for any other type amp. Why would it be different with the 45? What do you mean with out the noise? A 45 amp can be designed as quiet as you wish, no matter if PP or SE

Can this amp achieve the sound quality of an SET amp?

If you want the SE sound character that stay SE IMHO

Best regards

Some information: http://www.diyaudio.com/forums/tubes-valves/159177-push-pull-45-a.html

So far I have used the 45 only in Single Ended but will build a PP amp with them some time.

as the thread is about PP, I think it is not a problem to ask if you can tell a bit more about your ideas regarding PP implementaion? I learned a lot from your publications on SE, LCRs, amplifier construction, damper diodes usage, etc, and I am curious how you would tackle PP!


2010-12-17 3:22 pm
Thanks alot for replying, it has come to my attention recently that a 45 PP amp is available. I didn't know the 45 tube was ever used in this configuration and was wondering about the noise control. I have been led to believe that more power equals more noise...


2008-12-18 2:29 am
Yes it does. Thank you.
One could use three 2A3's I suppose if 45's are not available..

It is not the same thing. I have a 45 PP and I had 2A3 PP and PSE before. The 45 PP is better sounding and also measures better. However the 2A3 PP is very good choice and I prefer it to 300B's......
I get 10W clean watts from my PP. For me PP is better and I think the 45 SE is a little bit of a waste because 2W are really not enough with normal speakers. I don't like horns and huge high efficiency speakers at all....even less things like Lowthers..bleaaa!!:D
The best speakers for me are always stand mount (2 or 3 ways) with efficiency between 85 and 92 dB!;)

You can still find NOS 45's but they are expensive if new. However some used 45's can still be very good with plenty of life left. I have 3 quads, 2 are new in original boxes (RCA and Raytheon) and 1 quad used (Sylvania). I am using the latter in my amp because still measures almost like new and performs admirably.
You can also find new production 45's but they are expensive, again! Best current production 45's are Emission Labs, I think. In general I don't like Emission Labs small power tubes because they use huge bottles. Fortunately they have made a globe version of the 45 which is smaller and nicer. Their 45 is rated 11W. They also make a mesh plate version however mesh valves do not like to be driven into positive grid so the max power you can get is limited in comparison to the solid plate. Chinese 45's are not true 45's in my knowledge.


2010-12-17 3:22 pm
I want to thanks all who responded I am just trying to determine if a PP amp using a 45 tube is where I want to go??? Right now I am using an SET amp with a 45 tube and 106db speakers... Sometime I just wish for 1-2 more wpc and thought the PP might be the answer, comments???:D
I was so impressed w/ my first tube amp, which was single ended, that I avoided PP for years. None of my commercial PP amps sounded nearly as good. I figured it was the single ended "magic" I liked so much.
This winter I finally built a good PP amp, and it is every bit as good as the single ended.. If not better at times. (I suppose there are tradeoff's). Don't be afraid of PP :)

Right now I am using an SET amp with a 45 tube and 106db speakers... Sometime I just wish for 1-2 more wpc and thought the PP might be the answer, comments???:D

Assuming your 45 SET amp has 1.5-2W, 1 or 2 more Watts will achieve a mere 2-3dB in terms of sound level. That is not much. In order to make a noticeable difference you'd need at least 4 times the power.

What is the effect which you are hearing which makes you think you need more power? Sometimes the need for a better damping factor is confused with the need for more power.

If your output transformer can handle more current, your amp could probably be converted to 2A3 which would deliver double the power. I make all my 45 amps switchable between 45 and 2A3. But pretty much all the users of my 45/2A3 amps only use 45s, as I am doing myself

best regards



2010-12-17 3:22 pm
Ok brother thanks for the info and tips, I am not hearing anything that tells me I need more power. My backup amp is a PP using 6L6 tubes at 25 wpc and it just seems to have so much authority that I thought if my 45 just had a little more power, well you get it...