Best Firstwatt amp for backloaded horns?

[blue lander]

How does this look for an initial BOM? This is just for stuff I plan to buy from digikey, so I left out C1, C8, and C10 so I can buy fancy audio caps from parts-express or something. I'm ordering LU1014's matched at 1.06 vds from Deep Surplus, so I chose 2 ohms for R5. I've already bought a toroidal transformer from Antek so I can cross that off my list too.

 

[Tea-Bag]

Blue Lander, the small MUR's are not enough to handle the inrush current.
If using those kind of buggers from Digikey, I would recommend.

DSEI30-10A-ND x 8. And heatsink them or tie to chassis.

The whole amp runs like a stove top.

 

[blue lander]

Thanks Tea-Bag, I'll update the BOM. Maybe it'll be useful to some future amateur who wants to build an F3.

The Antek AN-4218 I ordered for the project just arrived. 400VA should be enough for an F3, right?

 

[DougL]

400VA should be enough for an F3, right?

That's about right.

 

[Russellc]

I've used the F5 with my sachiko horns for a long time and it sounds really good. Its not that high a gain (good for your sensitivity) and is very versatile if you choose other speakers. Another option may be the DeLite?


Fran

Sounded great on Altec A-7s as well. why in the world would you think the F-5 wouldnt be great with horns? I cant think of a reason. I understand you dont need the extra section, but then your back to "it may be too similar to the 45 SE" deal, no?

russellc

 

[blue lander]

The f5 is definitely still in the running. if I was to build an f3, would I be able to repurpose the power supply circuit in an f5?

 

[DougL]

The F3 and F5 Power supply boards are identical, just jumpers are different.
The rest is Identical, including the heat sink and case requirements.

 

[blue lander]

I read some more f5 reviews, I think I might have written it off too soon because it's push pull. I read a few user reviews at 6moons and it sounds like it's very popular among SET lovers who want to play with transistors. I'm going to build the PSU and the transistors for both the f3 and f5 since they seem to be in short supply, and then decide at a later date.

 

[Franz Gysi]

very popular among SET lovers who want

... to have as low distortion from the amp as possible and love to have a big bandwith.

Not knowing the F3 from own experience, but a lot of very fine tube amps.

The F5 is simply GREAT!

Franz

 

[Russellc]

... to have as low distortion from the amp as possible and love to have a big bandwith.

Not knowing the F3 from own experience, but a lot of very fine tube amps.

The F5 is simply GREAT!

Franz

Agreed! Although its interesting reading about F-4 also, the version that make 100 watts into 8 ohms has my attention, I just cant get my head around the notion that it doesnt have any gain? Does it drive things (powerwise) like any other 100 watt amp? Interesting, this whole line up.

Russellc

 

[Melon Head]

Yes, but obviously you need a preamp with gain.
You could also think of it like a 3 stage amplifier with source-follower push pull output (eg BA 2), but instead of it being in one box you put it in two boxes the first two stages are in the first box and source follower stage is in the second box.

You can also get 100W into 8Ohms with F5. You just need to cascode the input and obviously increase the voltage.

 

[blue lander]

Is there any benefit to building the cascode version of the F5 if you don't need the extra wattage? I read Mr. Pass's article about the cascode, it sounds like it reduces distortion from voltage fluctuations.

 

[Zen Mod]

try ;

then let your ears decide ;

that's what NP is keen to teach you , not to make blindly amp after amp

 

[Zen Mod]

after amp after amp after amp ..........

 

[Russellc]

Yes, but obviously you need a preamp with gain.
You could also think of it like a 3 stage amplifier with source-follower push pull output (eg BA 2), but instead of it being in one box you put it in two boxes the first two stages are in the first box and source follower stage is in the second box.

You can also get 100W into 8Ohms with F5. You just need to cascode the input and obviously increase the voltage.

Interesting. I'll read the Pass article on it and return. A 100 watt f-5...Hm.m.m.

Russellc

 

[Russellc]

Is there any benefit to building the cascode version of the F5 if you don't need the extra wattage? I read Mr. Pass's article about the cascode, it sounds like it reduces distortion from voltage fluctuations.

Which article is it? I see the 1978 cascode design only?

Russellc

 

[Melon Head]

Add the numbered components. Just about any bipolar devices
will do.

Click on the arrow in the quote.

You could try 40V rails or whatever your heatsinks can manage.

 

[tmblack]

Where does one buy the LU1014 JFET for the F3?
I would also like to build a phono preamp, which design would fit in with a F3 and possible B1 passive preamp?

 

[max426]

Electronic Components

http://www.diyaudio.com/forums/pass-labs/156397-pearl-two.html

a couple of options

 

[Tea-Bag]

Where does one buy the LU1014 JFET for the F3?
I would also like to build a phono preamp, which design would fit in with a F3 and possible B1 passive preamp?

I am not so sure Deep Surplus doesn't charge a crazy amount for overseas shipping. I would check. That was an issue in the F3 thread I believe.