2a3 or 300b

ditdah · 15830

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Offline Jim R.

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Reply #15 on: October 16, 2012, 03:25:15 PM
DD,

(Do you have a name, BTW?)

Let me confuse you a bit more... as you have the original Paramounts without the soft-start board, and if you ever plan to use EML tubes, you either need to stick with 300Bs or upgrade to the new, soft-start driver boards.  The direct coupling in 2a3 mode is too much stress on startup for the EML 2a3s and thus you need the soft start driver if you are ever want to use these tubes.

But, as Aaron and others said, you really should try both and listen for yourself and then pick based on your own reaction and listening preferences.  There's an awful lot in the listener/room/speaker equation that would pretty much make it impossible to predict which one would work better for you.

HTH,

Jim

Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline ditdah

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Reply #16 on: October 16, 2012, 09:36:52 PM
Jim,
Sorry didn't mention it earlier.  My name is Ken.  Nice to meet ya.

I don't have the paramount yet...I'm going to order it soon as Doc releases his package price with the BeePre.  So, It'll be the newest version with the soft start.

I think it's reasonable for me to say that I'll be trying both types of tubes eventually.  I am quite interested in trying the 300b's in direct coupled mode as Paul mentioned earlier.  All projects that are stacking up...  ...available time...just not enough of it (for me).

Kenneth Koller

Offline Jim R.

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Reply #17 on: October 17, 2012, 04:56:30 AM
Hi Ken,

Sorry, got you confused with somebody else.  Ok, here's yet another variation on the theme -- you can build the amp as a 300b with cap coupling, except wire the heaters for 2.5volts and use the JJ 2a3-40s or the sophia 2.5v 300bs.  In theory they may sound a bit quieter (if that is even possible) because of the higher current draw of the 2.5v filaments that will make the ps filter work a bit more quietly.  Sorry about that :-).

Just don't get stuck in analysis paralysis -- throw all the options in a hat and just pick one if you have to -- no matter how you slice it it will be a fine amp though one of the options will in the long run certainly prevail for you and your gear.

Good luck,

Jim

Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline Grainger49

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Reply #18 on: October 17, 2012, 05:10:31 AM
Hum doesn't have to be an issue unless you have speakers over 100dBW sensitivity.  Even then, remember that the heaters on the output tubes are DC heated, not AC like my Paramours. 

Just a for instance, I used the hum balance pots on my Paramours and got the hum down to 2mV on the better one and 5mV on the worse one.  That is very quiet.


Offline ditdah

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Reply #19 on: October 17, 2012, 09:38:44 AM
I think I'm quite fortunate to be part of a forum with so many knowledgeable folks...and I appreciate everyones comments and suggestions.  I kinda hope Doc takes a bit of time putting together the "package"...so I have time to mull this over.  Ultimately...I'll do as you say Jim...just gonna choose one and go with it.  I'm pretty interested in trying the alternate ideas as well...but we'll get to that point eventually.

Kenneth Koller

Offline Jim R.

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Reply #20 on: October 17, 2012, 10:07:49 AM
Ken,

I think you'll find that that is an integral part of the bottlehead experience and dare I say it,sometimes even more fun than the listening (depending on the individual, of course).   How many other audio manufacturers would not only encourage you to try different configurations for their gear, but also supply you with the how-tos?

-- Jim

Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline RPMac

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Reply #21 on: October 22, 2012, 07:59:20 AM
Quote from: Paul Joppa on October 14, 2012, 04:49:16 PM


As a side note, you can operate the 300B in direct coupled mode, by changing the audio circuit but leaving the filament power alone. This will give you a good part of the nuance available with the 2A3 in this amp, and the 300B will have a longer life when loafing at 15 watts. Many prefer the JJ 2A3-40, which is basically a 300B with a 2.5v filament.


I'm confused...aren't you saying to build in direct coupled 2A3 audio circuit and changing the filament power to 5 volts to operate the 300B in direct coupled mode?

Ken, don't worry about it, either way it's going to be good!


Offline Grainger49

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Reply #22 on: October 22, 2012, 09:15:34 AM
A last piece of advice.  As Paully's system went down in power I perceived it increasing in detail and a natural sounding midrange.  So I'm for the 2A3 or 45 if you can.

IMHO the question you should be asking is How Much Power Do I Need, that is a link to the FAQ thread and the question is question #3.  There are a number of factors.  Once you get a grasp on your power needs I would suggest the lowest power you can get away with.
« Last Edit: April 01, 2014, 03:24:09 AM by Grainger49 »


Offline Paul Joppa

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Reply #23 on: October 22, 2012, 10:10:36 AM
Quote from: RPMac on October 22, 2012, 07:59:20 AM
Quote from: Paul Joppa on October 14, 2012, 04:49:16 PM
As a side note, you can operate the 300B in direct coupled mode, by changing the audio circuit but leaving the filament power alone. ...
I'm confused...aren't you saying to build in direct coupled 2A3 audio circuit and changing the filament power to 5 volts to operate the 300B in direct coupled mode?...
You are not confused, you have understood it exactly. Except for filament voltage and maximum plate dissipation, a 300B is nearly identical to a 2A3.

Paul Joppa

Offline Reap

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Reply #24 on: December 14, 2012, 06:53:18 AM
I'm new here and new to tube amps but not new to system designs. I think I have the perfect solution that Doc should love. :)

Use 2 pairs. Run one with 2a3's for a tweet and small mid running @4k and up. Run the other pair on mid bass/sub bass on frequencies below 4k. Voila!

LOL, I know, you didn't want to spend that much.


Offline ssssly

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Reply #25 on: December 14, 2012, 01:20:23 PM
Could also build one of the two in 300b form and one in 2a3 form. Then compare them, decide which you like, and convert the other one to match.

I ordered a bee-pre and paramount kit on black monday. I will be building mine in 300b form to run the bottom end of my tri-amp setup now being powered by a modified paramour II. So I'm looking forward to the increased available power. While a 2a3 will move a Altec 416 quite well, it can run out of gas a bit when played at high volume.



Offline Reap

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Reply #26 on: December 14, 2012, 05:29:49 PM
Quote from: ssssly on December 14, 2012, 01:20:23 PM
Could also build one of the two in 300b form and one in 2a3 form. Then compare them, decide which you like, and convert the other one to match.

I ordered a bee-pre and paramount kit on black monday. I will be building mine in 300b form to run the bottom end of my tri-amp setup now being powered by a modified paramour II. So I'm looking forward to the increased available power. While a 2a3 will move a Altec 416 quite well, it can run out of gas a bit when played at high volume.



You going to use active crossovers to the amps?


Offline Reap

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Reply #27 on: February 22, 2013, 08:28:14 AM
I used to think I was indecisive but now I'm not so sure.  :-\


Offline denti alligator

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Reply #28 on: February 23, 2013, 04:18:13 PM
Would pairing the Paramounts with the BeePre make the decision of 2a3 vs 300b more obvious?

I 'm leaning toward the 2a3, in parts because my speakers are highly sensitive. But then will hum be more of an issue?

- Sam

Rega P3-24 (w/AT 150MLX) w/Groovetracer upgrades / Eros II / FLAC >J.River >DSD256 >Gustard X20 / Moreplay > Stereomour II / Klipsch Forte II w/Crites upgrades / C4S S.E.X. 2.0 +Nickel MQ Iron / Speedball Crack / Sennheiser HD600 w/Cardas cable

Offline Paul Joppa

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Reply #29 on: February 23, 2013, 05:01:25 PM
Generally speaking, 2A3 hum has half the voltage (6dB lower) than 300B hum. But Paramount has a DC heater supply, so hum is usually not a problem in either case.

Paul Joppa

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