Single Ended Amps - Opinions

[Littlewyan]

bepone - Nice clips, did your Trainwreck preamp have a stage between the preamp and power amp to simulate the PI?

wpaulvogel - That looks fantastic! Nice tidy work. Looks like a cathode follower driven tonestack and cathode follower driven power amp. I like the trimpot tone controls, how does it sound?

[bepone]

thx Littlewyan , my amp had classic Trainwreck schematic without PI, first stage ECC83 and last preamp stage was russian 6N1P tube, to have more current drive capability for KT88

[wpaulvogel]

bepone - Nice clips, did your Trainwreck preamp have a stage between the preamp and power amp to simulate the PI?

wpaulvogel - That looks fantastic! Nice tidy work. Looks like a cathode follower driven tonestack and cathode follower driven power amp. I like the trimpot tone controls, how does it sound?

The tone control is actually the midrange control of a Marshall tonestack except that as you can see in picture I paralleled a resistor across the 100k linear pot. By using this modification the pot is 30k full CCW and 100k full CW. It really scoops the midrange at CCW for really Fendery cleans that have thick bottom and sparkling top and creates a very nice mid bite full CW almost like a bypassed tonestack but not quite. There’s a pot on the second cathode follower grid that compresses the waveform and reduces gain. It squishes the output of the preamp which adds a real tubyness and helps lower the voltage swing to the power tube. It’s got fixed adjustable bias and runs at -16.5 volts to get 88mA bias from the cathode current of the KT88. It’s right at 410 volts plate voltage, so bias is 34 watts dissipation (subtract the 4mA screen current). All this gets the output waveform to go into cutoff clipping and grid current clipping at the same point but the leading (upside of the waveform) is wider than the down going wave which appears to me to probably produce some even order harmonics.
It’s a good sounding amp and much more interesting than any other single ended amp I’ve ever played. The output power is nice because it gets loud enough to couple with the guitar.

[ViperDoc]

Paging Mr. Vogel. Sound clips on Aisle 5.

That looks so cool.

[wpaulvogel]

Paging Mr. Vogel. Sound clips on Aisle 5.

That looks so cool.

I’m working to get some recorded. I’m not much of a player and I’ve got some guys that are. Just got to get them over to try it out.

[Littlewyan]

That sounds great. Nice range of controls there. What difference can you hear by adjusting the clipping of the output stage?

And we definitely need some clips!

[Tobyk]

Do you have a schematic to share please? I think SE is somewhat uncharted territory.

[10thTx]

To my ears ............... this is the coolest sounding single ended amp I've heard. It's Mat's mini-HRM that he shared with us many yrs ago. Sorta a Dumblish SE amp.

Mat is from Finland and just an incredible guitarist. Haven't seen him post on TAG in a long long time. Miss him being here!

If I had not known different, I would've thought this was simply a great sounding Dumble clone. To realize it's SE amp is pretty amazing, IMO.

https://www.soundclick.com/music/songIn ... id=8895338

https://www.soundclick.com/music/songIn ... id=8927753

https://soundclick.com/r/s5et4c

https://soundclick.com/share.cfm?id=8927752


Schematics and layouts here: https://el34world.com/Forum/index.php?topic=9149.0

With respect, 10thtx

[roberto]

Very nice! Is it this one?

86 Special volts.GIF

[Colossal]

Yes, that's it.

That was a very good sounding amp!

[10thTx]

IIRC, .............. I think Mat's first prototype was an HRM version using a 12Ax7 in the overdrive section. He then switched to an EF86.

I don't remember which amp was used in recording the soundclips? Maybe Colossal knows?

With respect, 10thtx

[bepone]

i remember something from that time, that was used 15" speaker...

[Tobyk]

Single ended

Pros: Preserves harmonics better than Push pull
Closer, more organic, direct feel. Often less bassy

Cons: Often harsher overdrive. More trebly.
More one-dimensional tone.

Agreed? But the cons can be remedied, I believe!

[bepone]

agreed not. you need to discover feedback also, then is not a problem

[Tobyk]

agreed not. you need to discover feedback also, then is not a problem

Yes feedback or maybe a zobel filter after the output transformer. Similar effect, I believe. Feedback cancels some 2H too, no?
And if you wanted to add a bit of compression to the sound, how would you do that?