Suggestions Wanted: 100 WPC

[TomMcNally]

I built a couple of amps for a friend of mine, he started with a
3/4 wpc Darling, last week graduated to a new ST-70, and now
asked me about something that will do 100 watts per channel.
I think he will hand the amps down to his kids as he gets
the new ones. It would make sense to give the Darling to the
kid who's music he likes the least ... hah.

I was thinking a pair of mono amps using the Poseidon drivers.

Does anyone have any ideas on which way to go ? It would
be nice to use some new MK-III chassis, but I don't know if
that's possible. For 100 watts I would think a PPP design
would be best. 4 x EL-34's ?

Thanks for any thoughts.

... tom

[TerrySmith]

Have a look at the Ikezilla in the eiclone section, should be easy to implement with Poseidon boards since they are basically the same circuit.

[Ty_Bower]

Didn't Blair try to build a 3x parallel PP 6550 amp using the Poseidon as the driver? His thread is somewhere in the two top forums. I thought he had some issues getting enough drive out of the Poseidons... dunno how they were ever resolved. I recall he had his power tubes triode strapped. Aren't triodes supposed to be somehow more difficult to drive?

[erichayes]

When I did the first 100 watt monoblock protos back in 2001, I used the same PT and choke that was in the 50/50 watt "HF-89". as well as the 50/50's drive circuitry--just added two more output tubes (and attendant screen and plate ballast resistors) and changed the output transformer to one with a 2150Ω primary (a real bear, getting that sucker wound right).

Of course, a lot of water has passed under the bridge since that first iteration--.08% THD back then vs .0027% now, for one thing--but they were very listenable with an absolute minimum amount of circuit tweaking.

[TerrySmith]

I wonder what would happen if you took a MK-3, discarded the driver board, make a plate to fill the hole, and hard-wire the HF-89 circuit using 12AX7 6SN7 tubes?? I did that once to a ST70, sounded very good, except the ground loop hum. Back then I was learning all about star grounds!

Also replace the 5AR4 with diodes- that will bump up the B+ to around 525v, hopefully the 6550 screens won't melt.

[Wmacky]

Let me know if you decide on something. I too would like 100W Monoblocks, and not sure if I should build or buy used. I wish something was out there with the ease of my new build DIYTube 70?

Hey Shannon how about boards for world class 100W blocks. Full regulation and everything. I'm just itching for another build if the right plan existed. It's kind of a dead end after the 70, unless your an electrical engineer..... I'm stuck!

[Ty_Bower]

...how about boards for world class 100W blocks. Full regulation and everything. I'm just itching for another build if the right plan existed. It's kind of a dead end after the 70, unless your an electrical engineer...

Not quite 100 watts, but Norman claims 80. It's got regulation and servos for DC balance and world class everything out the wazoo. Full plans on his website. Let us know if you manage to build one and get it to work.

http://www.normankoren.com/Audio/TENA.html

[battradio]

Hi Tom ,

If you want to use MKIII chassis you could an Edcor CXPP100-MS5K with with a pair 6550 to get 100 watts out using a Poseidon PCB or an Edcor CXPP100-MS3.3k using a quad of 6L6GGC's using the 5AR4 socket hole and the chassis cap hole for the two extra output tubes , in both cases solid state rectification would be needed and under chassis cap pcb with the 6L6's .

http://www.edcorusa.com/Products/Browse ... eriesID=32


With a scratch build Quad 6550's with an Antek AT-100L output transformer would be nice with a Poseidon circuit using AnTek power power transformers .

http://cgi.ebay.com/100W-Toroidal-Outpu ... 7C294%3A30

http://www.antekinc.com/trans.html



Mark

[Blair]

Didn't Blair try to build a 3x parallel PP 6550 amp using the Poseidon as the driver? His thread is somewhere in the two top forums. I thought he had some issues getting enough drive out of the Poseidons... dunno how they were ever resolved. I recall he had his power tubes triode strapped. Aren't triodes supposed to be somehow more difficult to drive?

He did

It was really an issue of adjusting resistors for the driver tubes since I used a 6SN7/6SL7 front end. I'm pretty sure I'm getting around 150w out of these beasts. Here is one of the preliminary schematics minus the much better bias circuit I ended up using Brik suggested.

I have not had a single person hear these amp that did not think they sounded more than amazing with tons of overhead. Oh, and the best part is that they still have mismatched ebay tubes in them!





Last pair. Sorry, I'm really proud of these:





Blair

[TomMcNally]

Thanks guys, I appreciate the ideas ... I have some Poseidon boards
and components, so they would be the logical driver ... Toroids
might be a good way to go, I could probably squeeze a stereo
amp on one big reinforced chassis. The first tube amp I built
about 12 years ago was the 100 wpc Velleman K-4000 ...



It's still shakes the house, thanks to a big pair of Cerwin-Vega! speakers.

[skidave]

Check out this link: http://www.the-planet.org/pdf/transformer.pdf

Go to pdf page 5. This is something I am slowing collecting parts to build using Poseidon boards. Feedback values need to be adjusted...

I have the two Hammond 1650 T output transformers... I will be planning to go with solid state rectification with some sort of simple timedelay or softstart circuit.

Again, I am slowly collecting parts. Life, work and kids is getting in the way of my hobbies!

Dave

[jukingeo]

I built a couple of amps for a friend of mine, he started with a
3/4 wpc Darling, last week graduated to a new ST-70, and now
asked me about something that will do 100 watts per channel.
I think he will hand the amps down to his kids as he gets
the new ones. It would make sense to give the Darling to the
kid who's music he likes the least ... hah.

I was thinking a pair of mono amps using the Poseidon drivers.

Does anyone have any ideas on which way to go ? It would
be nice to use some new MK-III chassis, but I don't know if
that's possible. For 100 watts I would think a PPP design
would be best. 4 x EL-34's ?

Thanks for any thoughts.

... tom

The poseidon should push a pair of 6550s to 100watts. I just worked on a 100watt amp for someone and converted the output from 8417's to 6550's. The amp is a beast and only needs two power tubes!

The only extra danger to watch out for is that you will need a 600volt (and then some) power supply. You will need a separate 300volt supply for the screens.

I was surprised at the end result. I clocked the amp to put out 112 watts. It sounded very robust to me. But it WAS a bass amp to begin with.

What I really did was create 1/3rd of an Ampeg SVT. The Ampeg SVT is a 300watt all tube amp that utilizes 6 6550's.

Geo