Pyramid-IX monoblock, 200W from 4x GU-50

[Wavebourn]

Originally Posted by Funker

Hi Waveburn,

Wow, 4 GU50 that will give your amp the real grunt. For my taste, I would prefer it with the narrow side to front.

I made a test setup with 6 of the GU50. I drive them hard into grid current (B2) They drive 450W into the Load at 1000V plate and 250V g2 . What an amazing valve. My aim is to build a Bass Guitar amp with these.

Yes, nice tubes. They were designed by Telefunken for military applications. They easily survive red anodes dissipating 100+ Watts, after that work like nothing happened.
Good luck with your Bass Guitar amp Wolfgang!

[Funker]

Hi Wavebourn,

see this thread, there are Pics an a digram of my test setup.

Real bass amps have tubes – semiconductors are musical director trainees


I came across about 30 GU50, so enough for further testings. By the way, I never managed to blew up even a single valve , as you stated they rugged like a tank. (what they are made for)

Please keep us informed with your neat little beasts!

73
Wolfgang

[Wavebourn]

Originally Posted by costis_n

Having faced the same dilemma recently, I can say that the only way that sensitive signals do not pass near the power supply AND not have the input jacks right on the front, is to have the long face forward. Then again, you can take a cue from Ming-Da preamps (yes, them), and have the narrow face front, but the inputs on the side forward.

I don't like sockets on sides. Better to use shielded cables.

I think I will probably design the chassis for 2 versions of orientation, with both versions of holes pre-cut. Extra hols will be closed by false-panels. Such a way I will have more freedom in the future. And 2 models of the amp on the same chassis.

[Bigun]

good job you don't design cars :-)

[Wavebourn]

Originally Posted by Bigun

good job you don't design cars :-)

I never saw cars with sockets on sides. Or what do you mean?

Actually, I worked for an automotive company. But I did not design cars. I designed information systems to steal money when manufacture and sell cars (just kidding - good information is valuable both to steal and to save money)

[costis_n]

Originally Posted by Wavebourn

I don't like sockets on sides. Better to use shielded cables.

I think I will probably design the chassis for 2 versions of orientation, with both versions of holes pre-cut. Extra hols will be closed by false-panels. Such a way I will have more freedom in the future. And 2 models of the amp on the same chassis.

I do not like them either, but to make something that is acceptable as a home appliance, you can't have them in the front either. Only if it is for temporary connection i.e. digital media player. That's why i vote for long side front

[Loren42]

Here are my thoughts:

1. I would turn all the components 90° on the chassis so you can space out the output tubes. I think they are spaced too close together and need more ventilation.

2. I would locate the two transformers all the way to the back and at opposite sides with the heat sink between them.

3. I would orient the front of the chassis on the long side so that all the output tubes are facing you and are equidistant from your point of view.

[Bigun]

Originally Posted by Wavebourn

I never saw cars with sockets on sides. Or what do you mean?

Actually, I worked for an automotive company. But I did not design cars. I designed information systems to steal money when manufacture and sell cars (just kidding - good information is valuable both to steal and to save money)

I mean, imagine if you designed car with doors on front and sides, just use which one according to whether you park parallel or straight in !

[quikie22]

Wavebourn,

Look forward to seeing the end result of this monster Pyramid. Really enjoying the GU-50 SE amp u helped design for me. Currently using 6E5P in triode as drivers. Dynamic, clear, powerful. All the best with this project :-)

[richwalters]

Interesting suggestion; I've also found that more powerful the tube amp is, the better the sound quality, esp at lower levels. Obviously the perception to overload is far reduced, but other boundary conditions must appear to be better optimised. Distortion may already be very low and undetectable; but what creates the transparency when good quality commercial components are used ? No deoxidised rubbish, no silver, nor gold connections. Yes, all my amps use input transformers, balanced line.
The sound quality of my Vampire 500W is astounding when at low sound levels is put against the original Mullard 20W design, or the GEC 88-50, 3 stage amp which is an excellent sounder. In the mid 1950's-60's these were considered, well designed. The 500W is the final design, the most complicated I've ever built, the best and there we have it.
Over decades I accumulated quite a collection of homebrewed tubed HiFi stereo amps, many are sold and my own favourite chassis is the two chassis 500+500W; I chassis 2x25W;2x7W..etc ...It's taken a long time to reach nirvana, what I consider the best quality tube amp for a given set of loudspeakers.
Others may have their liebling amps too.

richy