5 watt trainwreck for home

[geetarpicker]

I agree. Go full blown Express + nice attenuator, at least a THD Hotplate. They sound decent down to -12, which is about 2 watts net with 35 watts in.

[zambo]

I have built 2 se express type amps. they sound pretty cool to me. The cleans are not as good imo ( or the drive, I mean c'mon..lol..) but for these type of builds I got to say I am real pleased. Here are the vids. http://www.youtube.com/watch?v=9uOlMVAybFw http://www.youtube.com/watch?v=sETbe24Bu-4

sorry the sound is not the best but its enough to get the idea. I replaced the el84 with a 6v6gtg and the sound is 10 times better. I dont recomend the el84 at all. Both kits started as P1 and P1 Extreme from ax84. all i did was change the pre to Express and used a fake PI with 47k plate R and 22k cathode R.

[statorvane]

Wow. Those SE Expresses you built sound very good. I've got a P1 eX (6CA7 power tube) that I am thinking of modifying into something else. What speaker(s)/cab(s) did you use in the videos?

[rawnster]

Wow, zambo, those sound fantastic. Makes me want to grow my hair long and fire up the bong! Sweet. I'm very interested in the 5 watter. Is this your secret sauce, or have you posted any pics/schematic of either build? I'd like to try my hand at it. Thanks.

[zambo]

Thanks!The only secret sauce is a fake pi ( essentialy another gain stage in this case) with 47k plate R ans 22k Cathode R unbypassed compliments of Zoe n Lain over at ax84. On the 5 watt I have a presence knob from the speaker out to the last gainstage( fake pi) before the power tube .On the 10 watt I have a master volume. I like the master volume. The presence is ok but I could live with or without it I think. Other than that i used all the stock preamp values from the express schematic found on this sight. Thanks by the way for all the info on here!

[BT123]

I have an S2 Micro amp that sounds great. 2 -EL91s push/pull for 5 watts and power scaling to get it to bedroom levels.

Just another option for a cool build.

[zambo]

2 el91 in pp will get you 5 honest watts? Are you using the 269ex transformer? What kinds of b+ are you running? I would love to know, That sounds cool!

[drew]

Wreck Junior: https://tubeamparchive.com/viewtopic.php?t=2831

[BT123]

I'll try to post some pics when I have time. Looks like Hammond transformers.

[RJ Guitars]

There used to be an old saying that a 5 watt guitar amp was about as loud as a trumpet... I don't know that it's true but for a home amp that can be pretty loud. I found something between 1/2 to 2 watts was the answer as far as a home and small venue amp goes... but even these amps are too loud for an apartment amp.

Single ended Wrecks are around and the suggestion to dial a full sized Wreck down using Master Volume, Power Scaling, or Attenuators have all delivered good results... YMMV.

If you are interested in sub 2 watt amps that preserve the push pull part of the circuit then check these out -
https://tubeamparchive.com/viewtopic.php?t=6159
https://tubeamparchive.com/viewtopic.php?t=9816

It will take a little bit of searching to find all the low wattage Wrecks that have been done, but it should prove good reading along the way.

enjoy,

rj

[M Fowler]

I enjoy noodling around with my SE Swamp Thing amp it has high and low mix pots on V1 into TMB and master. Using a EL34 right now.

Mark

[ampgeek]

Zambo,
Nice "little" screamers goin on there! Love it!

Quick question: Using the P1 Extreme as a reference, did you put the fake PI/gain stage before or after the tone stack?

TIA,
Dave O.

[surfsup]

zambo interesting, I just build an ax84 HO and maybe I can do this.

all i did was change the pre to Express and used a fake PI with 47k plate R and 22k cathode R.

I just saw this so haven't googled it yet but "fake PI"? anyone care to explain a little more about that?

[UR12]

I just saw this so haven't googled it yet but "fake PI"? anyone care to explain a little more about that?

Some Push Pull amps will have a PI stage that actually produces gain. These are the long tail variety. So to make up for not having a PI stage in a SE amp you can add an extra stage to give you the same gain as you would get from the normal PI. I have also incorporated a fake PI for a mixer stage on a 2 channel SE amp that I built for mixing the two preamp channels together before the final power amp stage. Works pretty good at keeping the Gain structure of the original PP design when changing to SE.

Most SE amps are also cathode biased amps. If you want to keep the characteristics of the PP amp on the SE version I would highly recomend going with a fixed bias also.

[M Fowler]

Dana did you ever build a DLM trainwreck?

That is something I wouldn't mind building at some point.