[Jaytor]

I'm considering building a pair of 300B SET monoblocks as my next project. Does anyone have any experience using this type of amp with the NX-Oticas or NX-Tremes? I will probably build an amp with two parallel 300B tubes, so 14-16W.

[mkrawcz]

Well I don’t have monoblocks, but I do have a hot rodded Elekit tu-8600s 300b and it works well on the NX-Oticas. It really shines with vocals. I imagine monoblocks will be an improvement.

[Jaytor]

Well I don’t have monoblocks, but I do have a hot rodded Elekit tu-8600s 300b and it works well on the NX-Oticas. It really shines with vocals. I imagine monoblocks will be an improvement.

Thanks for the reply. Are these single 300Bs per channel? Do you think they have enough power to give you enough volume? How big is your room?

[Hobbsmeerkat]

I borrowed a pair of Tsakiridis 300B momoblocks from Ron.
I used them with my X-Statik for a couple weeks. It was a great combo, tho Danny thought the bass sounded rather bloated/uncontrolled at Rons place.

Danny also has an Elekit 300B stereo amp that sounds really good too that I have heard on the NX-Tremes.

So I'd say got for it.

[mkrawcz]

Thanks for the reply. Are these single 300Bs per channel? Do you think they have enough power to give you enough volume? How big is your room?

Yes, single 300bs 9.2w per channel. The room is 15'x18' (actually larger then that as it extends to the kitchen) and it goes fairly loud. The bass will not be as tight as your SS amps but it produces a lot of it and the amp is very detailed.

[Jaytor]

I decided to go for it. I am going to build my own chassis for the two monoblocks, but I ordered most of the parts from ANK based on their Interstage parallel 300B kit with C-core interstage and output transformers.

I'm making my own chassis because I have a bunch of features I want to add and change from the basic design (balanced inputs, speaker protection and delayed start circuit, etc.), but the circuit itself will be more-or-less the same with a few component, connector, and wiring upgrades.

My room is pretty large at 17' x 29', but I once jay (captainhemo) finishes my cabinets, I'll be replacing my NX-Oticas with Line Forces which are significantly more efficient and crossover at a higher frequency to the subs, so these amps should do nicely.

[Hobbsmeerkat]

Looking forward to it! 

[NoahH]

My room is pretty large at 17' x 29', but I once jay (captainhemo) finishes my cabinets, I'll be replacing my NX-Oticas with Line Forces which are significantly more efficient and crossover at a higher frequency to the subs, so these amps should do nicely.

Line Force? I thought those were delayed indefinitely from driver shortages. Are those imminent?

[Jaytor]

Line Force? I thought those were delayed indefinitely from driver shortages. Are those imminent?

I ordered enough BG Neo 10 drivers from Parts Express last summer (2020) and finally received them last November just before they discontinued them. I've been working with Jay to get the cabinets built but he's been so busy with all the other GR product orders and also has had some difficulty getting the composite material that the line Forces require, so the cabinets have been delayed. But it doesn't look like it will be too much longer. In the meantime, I've collected all the other parts.

I don't think Danny is ready to resurrect them until he has a source for the NEO 10 drivers that he can control.

[mkrawcz]

I don't think Danny is ready to resurrect them until he has a source for the NEO 10 drivers that he can control.

Unfortunately, that will probably never happen. My theory is that PS Audio owns the rights to that driver because it will be in there new speaker.

[Hobbsmeerkat]

I believe we're working with Radian on an alternative to the Neo 10. But it's still a ways off for now.

[NoahH]

Thanks for the update.

[Jaytor]

I've been working on my plan for the 300B amps. As I mentioned, I ordered the ANK C-Core Interstage Monoblock kits without the chassis. I am going to use Front Panel Express to make the the panels for the chassis. This will add a fair amount to the cost, but I've been very impressed with their quality and their design tool is easy to use. I'm going to powdercoat the panels using their Gray-White color. This is the color I'm using for my new preamp (almost done) and it's come out really nice.

To the normal kit design, I'm making the following changes:

• Both balanced and upbalanced inputs with a toggle switch to switch back and forth. The balanced inputs will use a Jensen 1:1 line input transformer. Viborg gold over copper connectors.
• Dual speaker connections with EIZZ binding posts and GR-Research Tube Connectors.
• Neurochrome soft-start with front-panel mounted illuminated vandal switch for power on/off.
• Speaker protection circuit with turn-on delay to allow the voltages to come up to spec before connecting the speakers.
• Regulated DC power supply for the 6SH7 driver tube heater (standard kit uses an AC heater circuit).
• Neurochrome 21st Century Maida Regulator for the driver stage B+ (standard kit derives this with a simple RCRC filter from the main B+).
• Grid resistors on all three tubes upgraded to Audio Note 2W Non-Magnetic Silver Tantalum resistors.
• Extra-thick chassis panels to improve stiffness - top and bottom panel will be 6mm (standard kit uses 3mm panels).

The chassis size will be a bit bigger than the standard kit to accommodate all the extra PC boards (a couple inches in width and length). This will also allow the transformers to be spread out a bit more which will reduce magnetic flux leakage interaction.

I kind of like the look of the C-Core transformers, but the main power transformer and choke are pretty ugly, so I plan to build a cover as part of the enclosure design - probably powder-coated black, but I'm considering something like red or blue just for fun.

Once they are up and running with the default tubes, I will start thinking about some tube upgrades - particularly the 300Bs (thinking about Takatsuki, new WE reissues, or LinLai Elite).

Here's what the standard kit looks like (one channel shown) - I'm keeping the copper plate 

[mkrawcz]

This is very interesting. Definitely looking forward to your impressions. For tubes, you may also want to take a look at Elrog 300bs. They are supposed to sounds pretty amazing. 

[Early B.]

I've been working on my plan for the 300B amps.

Jaytor -- go ahead and make another set for me, man. Thanks.

You're gonna invite us to participate vicariously through a build thread, right?   

[Jaytor]

Jaytor -- go ahead and make another set for me, man. Thanks.

You're gonna invite us to participate vicariously through a build thread, right?   

I am posting a build thread on the Steve Hoffman forum for anyone that is interested.

https://forums.stevehoffman.tv/threads/ank-300b-interstage-monoblocks.1112018/

[Jaytor]

My first amp is complete. See the previous post for a link to the build thread on SH.

Now on to the second one.

[mkrawcz]

Dude! That is some serious business right there.

[Tyson]

Jesus Christ.

[NXSTUDIO-DRUMMER]

Looking forward to your first impressions on your new amps when completed. What's your opinion on the building instructions manual and customer support with ANK? Hopefully they're a tad better than IKEA, with assembly instructions.