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Old 30th November 2004, 02:11 AM   #1
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Default Eventual 300B advice welcome!

I love the first 2A3 amp I made not long ago. The wonderful sound make me want to explore the "famous" 300B as my ultimate amp to enjoy! In searching the design available, I would invite all the expert in tube amp diyer to help me make good decision on the following:

1. for 300B amp, would Audio Note Kit one or JE Labs 300B has better sound? (or has a better chance of good sound with right parts?)

2. The (power) transformer seems to be the decisive factor for a good 300B amp (besides tubes). Any suggestion for good quality one with reasonable price?

3. I normally use two sources regularly (CD and FM). Is using preamp make more sense for 300B or direct in is better?

4. If direct in is better, I am thinking of using a toggle sw to switch the source. Is this a good idea? (because I have not seen anyone done this on 300B amp)

Many thanks,

Thomas
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Old 30th November 2004, 03:43 AM   #2
tom1356 is offline tom1356  United States
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If your looking for a kit do yourself a big favor and check into the Ladyday's from DIY hifi.
http://www.diyhifisupply.com/diyhs_ladyday.htm

While you will not need a preamp, you will need a volume control.
Good luck with your project.
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Old 30th November 2004, 03:53 AM   #3
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Default Re: Eventual 300B advice welcome!

Quote:
Originally posted by tomchaoda
I love the first 2A3 amp I made not long ago. The wonderful sound make me want to explore the "famous" 300B as my ultimate amp to enjoy! In searching the design available, I would invite all the expert in tube amp diyer to help me make good decision on the following:
Quote:
1. for 300B amp, would Audio Note Kit one or JE Labs 300B has better sound? (or has a better chance of good sound with right parts?)
The cascaded 6SN7 drivers in the JE sounds like mud. Something like one of Thorsten's 300B designs using either a pentode (my fave) or a 6C45/417/other high mu triode like 8532/6J4

Quote:
2. The (power) transformer seems to be the decisive factor for a good 300B amp (besides tubes). Any suggestion for good quality one with reasonable price?
I think you mean output transformer, the power transformer, provided it's of decent quality is fairly trivial.
Some suggestions; Magnequest, Lundahl, One-Electron, Electraprint, James, Tamura, Tango. Depends on your budget mainly.

Quote:
3. I normally use two sources regularly (CD and FM). Is using preamp make more sense for 300B or direct in is better?
You might not need a preamp. Build the poweramp with a switch (source selection) and a volume control and see what you think. If you need more, build a preamp. If not, drill some holes and install them into the chassis.

Quote:
4. If direct in is better, I am thinking of using a toggle sw to switch the source. Is this a good idea? (because I have not seen anyone done this on 300B amp)
A toggle is fine, provided it's a make-before-break type so it doesn't 'pop' when you change sources.
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Old 30th November 2004, 03:57 AM   #4
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You don't 'need' the gridchoke in the design above.

Below is my fave. I used something similar, with a variety of pentodes driving bigger bottles like the GM70/813
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Old 30th November 2004, 04:01 AM   #5
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Any thoughts about Audio Note Kit One?

Thomas
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Old 30th November 2004, 04:39 AM   #6
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Default VIVA 2A3...CHEAP AND CHEERFUL.

Hi,

First of all I think you won't notice much of a difference between a 300B and a 2A3 except perhaps for a tiny bit more power output from the latter.

IMO, the 300B is about the most overrated powertube ever and I'd personally rather listen to a PP 2A3 than having to live with only a so so 300B amp (and that's the vast majority of them).
With the exception of the AN Baransu 300B amp, all others I hgeard so far were nothing but dissapointment, to my ears at least.

Furthermore, the driverstage of such an amp is actually the one that will determine most of what the amp is going to sound like, the powertube is not amplifying anything to a significant enough degree to be dominant.

Penthode + DHT is often a good combo as is high gm triode + DHT.
The rest of the pitfalls I suppose you know already so no need to rehash them here.

Cheers,
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Old 30th November 2004, 02:50 PM   #7
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Quote:
IMO, the 300B is about the most overrated powertube ever and I'd personally rather listen to a PP 2A3 than having to live with only a so so 300B amp (and that's the vast majority of them). With the exception of the AN Baransu 300B amp,
Frank and all:

Is Audio Note Japan's Baransu 300B SE amp schematic available? I was not able to find in their web site (japan) about this design, nor anyway of its schematic!

Thomas
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Old 30th November 2004, 02:59 PM   #8
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Hi,

Quote:
Is Audio Note Japan's Baransu 300B SE amp schematic available?
Not that I know of.

It uses 5692 and 5R4GY besides the obvious 300B, all wiring is high-purity silver including the OPT's primary and secondary windings. Silver foil coupling caps, tantalum resistors...IOW the works.

Mayb Thorsten Loesh knows more about the topology of the beast...

Cheers,
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Old 30th November 2004, 03:03 PM   #9
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Frank:

My thinking is to keep this tiny (and easy to move) 2A3 as my small room enjoyment and build one 300B for the family room (a bigger room). Somehow, from my study, I don't like PP or Parellel design! Maybe I am wrong, but I will stick w/ 300B SE so far.

Thomas
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Old 30th November 2004, 03:10 PM   #10
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Hi,

Quote:
Somehow, from my study, I don't like PP or Parellel design! Maybe I am wrong, but I will stick w/ 300B SE so far.
De gustibus et coloribus.....
Anyway, I'm sure that you can make yourself a far better 300B amp (SE or otherwise) than most of the commercial offering I've heard so far.

I think the key lies with the driver and PS. If you opt to go for a DC feed on the DHT then that becomes a critical issue as well.
Easy enough to go for AC and get it quiet on a 2A3, not so simple with the 300B though.

Cheers,
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