[UntilThen]

Bald headed tubes. Not too bad looking.

 

[baronbeehive]

Bald headed tubes. Not too bad looking.

Don't know about 300B'a but TJ's aren't bad sounding either.

 

[UntilThen]

Don't know about 300B'a but TJ's aren't bad sounding either.

What I wanted to do is to hear for myself a budget 300b tube and one that is supposedly pricey. I had to be satisfied that the megabucks that WE, Elrog or Takatsuki charges are worth it. Or is it just the consumer believing that anything that is expensive has to be much much much better.

 

[bcowen]

What I wanted to do is to hear for myself a budget 300b tube and one that is supposedly pricey. I had to be satisfied that the megabucks that WE, Elrog or Takatsuki charges are worth it. Or is it just the consumer believing that anything that is expensive has to be much much much better.

Nope.

 

[SonicTrance]

It's finally complete! Here's the push pull version of Odyssey!

It's setup as a power amp so no volume control. 6SL7/6SN7 driver tubes, cathode biased. Then you have adjustments galore for the output stage. The anode voltage can be set from 250V-400V. Then you set the negative grid bias for each output tube. The mA meters measures one tube at a time. Just flick the toggle switch towards the tube you want to measure. I included a 125mA fuse for each output tube just in case one should forget to adjust the bias.

As you can see the mains transformer is slightly pushed back. This is because we were having an issue with the Monolith mains and decided to replace it. And so to not have to rebuild the entire amp we pushed the new transformer back a little to cover up old mounting holes.

We also added extra banana jacks at the back panel. One set for the power tubes and one set for the driver tubes. This is for external heater power supplies. They are connected to the two big toggle switches on the top plate. Toggle up for internal 6.3V or down for external heating.

It can run both triode and ultra linear for the power tubes.

The switches on the front are impedance, 4/8 ohms, and output selector, speakers/headphones.

 

[UntilThen]

Another beautiful Ultrasonic Studio amp. It looks alright with the mains tranformer push back a bit. Now I have a glimpse of how Telemachus with those Monoliths transformer will look.

 

[bcowen]

It's finally complete! Here's the push pull version of Odyssey!

It's setup as a power amp so no volume control. 6SL7/6SN7 driver tubes, cathode biased. Then you have adjustments galore for the output stage. The anode voltage can be set from 250V-400V. Then you set the negative grid bias for each output tube. The mA meters measures one tube at a time. Just flick the toggle switch towards the tube you want to measure. I included a 125mA fuse for each output tube just in case one should forget to adjust the bias.

As you can see the mains transformer is slightly pushed back. This is because we were having an issue with the Monolith mains and decided to replace it. And so to not have to rebuild the entire amp we pushed the new transformer back a little to cover up old mounting holes.

We also added extra banana jacks at the back panel. One set for the power tubes and one set for the driver tubes. This is for external heater power supplies. They are connected to the two big toggle switches on the top plate. Toggle up for internal 6.3V or down for external heating.

It can run both triode and ultra linear for the power tubes.

The switches on the front are impedance, 4/8 ohms, and output selector, speakers/headphones.

Beautiful!!

 

[baronbeehive]

It's finally complete! Here's the push pull version of Odyssey!

Best looking amp yet, and I love all those switches .

 

[SonicTrance]

Another beautiful Ultrasonic Studio amp. It looks alright with the mains tranformer push back a bit. Now I have a glimpse of how Telemachus with those Monoliths transformer will look.

Yes, you have! It's this exact transformer cover I'll use on yours (and mine) Telemachus. It matches the Monolith's very nice!

Beautiful!!

Best looking amp yet, and I love all those switches .

Thanks guys!

 

[UntilThen]

Yes, you have! It's this exact transformer cover I'll use on yours (and mine) Telemachus. It matches the Monolith's very nice!

Are the transformers on Telemachus the same size as that used in this Odyssey amp?

 

[Isaacc7]

It's finally complete! Here's the push pull version of Odyssey!

It's setup as a power amp so no volume control. 6SL7/6SN7 driver tubes, cathode biased. Then you have adjustments galore for the output stage. The anode voltage can be set from 250V-400V. Then you set the negative grid bias for each output tube. The mA meters measures one tube at a time. Just flick the toggle switch towards the tube you want to measure. I included a 125mA fuse for each output tube just in case one should forget to adjust the bias.

As you can see the mains transformer is slightly pushed back. This is because we were having an issue with the Monolith mains and decided to replace it. And so to not have to rebuild the entire amp we pushed the new transformer back a little to cover up old mounting holes.

We also added extra banana jacks at the back panel. One set for the power tubes and one set for the driver tubes. This is for external heater power supplies. They are connected to the two big toggle switches on the top plate. Toggle up for internal 6.3V or down for external heating.

It can run both triode and ultra linear for the power tubes.

The switches on the front are impedance, 4/8 ohms, and output selector, speakers/headphones.

SQEEEEEE!!! It’s finally happening! Guess I should get the stand built and cables bought lol.

I’ve being poring over tube curves and haunting various sites to get operating points for the various tubes I want to use. Looks like I’ll be able to hit the sweet spot for my 6l6 family of tubes (KT66, 807, 6ar6, 7581a), but also the 6v6 family (6/12v6, 6f6, 6k6, 6aq5) as well. That makes up the bulk of my output tubes. Add the el38/e3375 and I’ll be set for now. Have a few other more esoteric things in the wings (GU50, 12av5, 2e26) but those can wait.

As far as the input tubes go, I’ve got a zillion of those as well. 6/12sn7, 6/12sl7, 6f8g, 6c8g, 2c50, 12sx7, 11n7, ecc31. There are a bunch of brand and construction variations of those tubes as well. Also have a bunch of 6/12j5gt And now some 6c5g. At first I was kicking myself looking at my new amp, I’ll never be able to put those adapters on the amp, the tubes are too close! Should’ve told Tomas to keep that in mind. But then I remembered that the adapters from @Deyan actually rotate so I should be fine.

If you follow the pentode thread you know that I have been trying all of my output tubes in my current amp, a Dennis Had Inspire KT88 Firebottle. It is a single ended pentode amp. My new amp will run the tubes in either triode or Ultralinear. I fully anticipate very different sounds because of the different topology and more power. Because I can now adjust the anode voltage and the bias current I also expect to be able to change the sound that way as well. Time to rediscover my tube collection!

 

[baronbeehive]

... I fully anticipate very different sounds because of the different topology and more power. Because I can now adjust the anode voltage and the bias current I also expect to be able to change the sound that way as well. Time to rediscover my tube collection!

I'm interested in how the amp will sound different due to the topology too.

How do you set the negative grid bias on the amp?

 

[Isaacc7]

I'm interested in how the amp will sound different due to the topology too.

How do you set the negative grid bias on the amp?

There are ports for a meter next to each output tube. Set the bias and voltage (via the center meter), turn off the amp, wait 5 minutes, put in tubes, then turn on. That’s the way @SonicTrance wants it done. Once the tubes are warm check the bias meters and correct as needed.

 

[senseitedj]

The feature with input ports for the heater voltage supply is really neat! Those monolith transformers really do live up to their name.

 

[Isaacc7]

The feature with input ports for the heater voltage supply is really neat! Those monolith transformers really do live up to their name.

I had originally asked for a simple 6v/12v switch for both input and output tubes. Spending too much time on the internet, and money, let me to looking at other voltage tubes. I own 11n7 and 16gk6 tubes. I have also started to look into the world of old British 4v tubes. Having external supplies is the easiest way to have the most flexibility.