2a3 or 300b

D

ditdah

New member
As the subject would hint to...  I'm at a loss at figuring out which tube to go with in my first Paramount build.  Yes, I know...subjective...  Out of the posts I have read so far...I get the following points:
-2a3's...not as much output as the 300b
-300b's...issue with bass or not as much bass or saggy bass?

Point being...I have no idea which way to go and would appreciate suggestions.  Not sure if it plays into the choice...but I'll be getting the BeePre and using it with this set of paramounts.

Thx everyone
 
The bass of the 300B Paramount is very good. The differences are that the 2A3 will have a tiny bit more resolution because it is direct coupled, and to my ear the 300B has a little nicer lower midrange performance as well as better punch. I lean toward the 300B with the speakers I use.
 
The good news is no matter which way you go, you can always change with a circuit modification.  I originally configured 300B thinking more power, more better.  I then needed something to do, so I changed to 2A3 and haven't looked back since.
 
I already had a 300b amp so I built mine with 2a3's.

find the 2a3's more detailed.  The 300b sounds more forceful, but I really like the musical nuances I hear with the 2a3.

Deb
 
I appreciate everyones comments.  Doesn't make my decision any easier though.  I've gone from considering 300b to 2a3 to 300b...and now back to 2a3... again.  
 
Well remember, it is pretty easy to convert back and forth. your decision is not set in stone...John 
 
True true...but deciding what to do initially is killing me.  I guess I just need chose one and go go go.
 
I suggest starting with the 300B. The 2A3 arrangement is direct coupled, which is a more tricky approach; the operating points (voltages and currents) of each stage are critically dependent on the other stage. There are just more ways things can go wrong.

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.

All that said, of course the current Paramount has the new 5670 driver with the new "soft-start" board, which allows adjustment of the critical driver plate voltage. This solves one of the tricky tricky issues the direct coupled circuit.
 
Another thing to consider.  How big is your listening area, and how sensitive are your speakers? If you have a small room or sensitive speakers 2a3 would be the best pick.
 
you know...I'm really really really trying to NOT get 2 sets of these amps (money...time...etc...).  However, it would solve my indecision...  wait...I decided...

I'm decidedly indecisive.
 
Poster Paully has had his one set of Paramounts set up as 300B, 2A3, 300B, 2A3, 45, 300B.  It doesn't take much to swap from one to the other.
 
You need to base your experience off of your ears listening to your system.  It take an hour or so to switch the amps around per amp so don't lose sleep over it.  Find your own way.  That's what makes this audio journey so much fun!  What sounds good in someone elses system may sound horrible in yours ;-)

I wrote a long thread about my time with the Paramounts and my own experimentation.  In the end, they didn't give me what I needed but it was a fun trip :)  
 
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,
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).
 
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
 
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.
 
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.
 
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