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DjOverdose

Planning on changing amps from PP KT120 to SET 2A3

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That's the plate rating for that particular tube. Same as the new Western Electric 300B tube.  I certanly don't know what the expected power output can be.

 

Bruce

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That's the plate rating for that particular tube. Same as the new Western Electric 300B tube.  I certanly don't know what the expected power output can be.

 

Bruce

 

Around 3.5W for a 2A3. Around 8W for a 300B.

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2 hours ago, codewritinfool said:

Around 3.5W for a 2A3. Around 8W for a 300B

 

This is correct, just pointing out the plate dissipation rating for the JJ 2A3 40 tube is 40Watts.

 

https://www.tubedepot.com/products/jj-2a3-40-watt-power-vacuum-tube

 

The new WE 300B has the same maximum plate dissipation.

 

https://www.google.com/search?q=new+western+electric+300B+spec+sheet

 

If you run the 300B at near maximum, you can get approx. 17 watts out.

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I wouldn't want to waste a new WE 300B by doing that, though. Not at $1500 a pop... 😟

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On 5/28/2019 at 9:54 AM, DjOverdose said:

i only have a small space for the speakers though. ive read somewhere that the reference are not that sensitive as advertised. 

 

since its a custom amp, i can have an option to switch from 2a3 to 300b with a togfle switch and from 2a3 to 45 by just adjusting the bias... 

 

 

I'd suggest, forget a 300B, avoid unnecessary toggle switches, and amplifiers needing adjustments.  KISS rules !! . 

 

The 300B  requires a DC filament operation, due to its 5 V filament requirement.  Have your amp built using ONLY  JJ 2A3-40s, which is a SINGLE 40 Watt ( 300B ) plate tube, with a symmetrical harp-like cathode,  and a 2.5 VAC filament requirement, so you can employ AC heating, which sounds better !! 

 

The JJ 2A3-40, properly employed,  just totally destroys every Type 45 tube amp I have built and heard, on my system, but I have not heard a solid plate EML.  ( The solid plate EML $$$$$$  also has a symmetrical harp-like cathode and advantageously, a single plate ) and its made in the same Prague Factory as a $130 JJ 2A3-40 !!  

 

Be sure to use good wiring, in the amp, and all the way to the Klipsch Drivers' speaker terminals / and / or to the Drivers' voice coil terminals.  I did this, this last year, with a 0.25 Watt triode amp, and it has made a world of difference.  

 

Never operate tube plates near maximum ratings, first of all, they SOUND worse -  thermally stressed that way, and their useful life is drastically reduced.

 

Jeffrey

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On 6/10/2019 at 6:31 PM, DjOverdose said:

ill be having it on a single chasis. another local builder told me that there is little difference from the mono blocks and single chasis. but cost wise theres alot. 

 

Heres the chasis of my 2a3 amp. itll be powered by a pair of jj2a3 40 rectified by 5u4gb tubes. i forgot the other tubes that will be put in. 

received_449901588902649.jpeg

received_2361953943890798.jpeg

 

 If you have a good stereo amp design, simply listen to just ONE channel, playing one speaker, and decide for YOURSELF. 

 

I find that the local builder told you wrong.  I have often made the same mistake !! 

 

There really is no comparison to what monoblocks do,  after you do the above mentioned test I suggested. 

 

My 2019 KT88 will become the LAST stereo amp I EVER build for myself.

 

Jeffrey 

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I agree that listening to a single channel (use the same channel for both amplifiers) to listen and evaluate is a good idea as listening to stereo can be confusing, you can get lost listening to stereo effects and not the hear as easily the balance of the amp under test. Choose a mono recording or if you don't have one a single channel of a tune in stereo that you know well which has a good wide range of information/instruments on it. This also results in eliminating half of your room interactions present in a stereo listening set up so that will help to make it easier for you to hear what each amp is doing.

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6 hours ago, Schu said:

He's expecting 40w out of a 2a3?

nope... thats the model of the power tubes. 

Screenshot_20190629_002113.jpg

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1 hour ago, Jeffrey D. Medwin said:

 

I'd suggest, forget a 300B, avoid unnecessary toggle switches, and amplifiers needing adjustments.  KISS rules !! . 

 

The 300B  requires a DC filament operation, due to its 5 V filament requirement.  Have your amp built using ONLY  JJ 2A3-40s, which is a SINGLE 40 Watt ( 300B ) plate tube, with a symmetrical harp-like cathode,  and a 2.5 VAC filament requirement, so you can employ AC heating, which sounds better !! 

 

The JJ 2A3-40, properly employed,  just totally destroys every Type 45 tube amp I have built and heard, on my system, but I have not heard a solid plate EML.  ( The solid plate EML $$$$$$  also has a symmetrical harp-like cathode and advantageously, a single plate ) and its made in the same Prague Factory as a $130 JJ 2A3-40 !!  

 

Be sure to use good wiring, in the amp, and all the way to the Klipsch Drivers' speaker terminals / and / or to the Drivers' voice coil terminals.  I did this, this last year, with a 0.25 Watt triode amp, and it has made a world of difference.  

 

Never operate tube plates near maximum ratings, first of all, they SOUND worse -  thermally stressed that way, and their useful life is drastically reduced.

 

Jeffrey

hey jeff. thanks for the input. i have no ideawhat wires his using inside the amp. im using a QED XT silver anniv as my speaker wire. i wonder what the speaker will sound like and using a copper one. i cant do anything About the toggle switch since it was alrradu6 thetr. 

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On 6/28/2019 at 11:32 AM, DjOverdose said:

hey jeff. thanks for the input. i have no ideawhat wires his using inside the amp. im using a QED XT silver anniv as my speaker wire. i wonder what the speaker will sound like and using a copper one. i cant do anything About the toggle switch since it was alrradu6 thetr. 

 Copper plays the mids.  Silver content adds high frequency response, as  is wider band and more conductive.  Pure silver is cost prohibitive. 

 

In 2019, April on,  I use a stranded copper, with each strand individually silver plated.  133 strands of 29 AWG , in a teflon jacket.  Military wire.  8 AWG !!!  $2.00 a foot on eBay, or Steve at APEX Jr. 

 

M22759/11  8    or      16878/4 or 16878 /5    ( 600 and 1,000 VDC rated)  in 8 AWG.

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On 6/28/2019 at 10:37 AM, Jeffrey D. Medwin said:

The 300B  requires a DC filament operation, due to its 5 V filament requirement. 

 

My 2A3s have a 5 volt filament and don't require dc. The amps would be quieter if I did, though.

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1 hour ago, Marvel said:

 

My 2A3s have a 5 volt filament and don't require dc. The amps would be quieter if I did, though.

Thats highly unusual.  I have never heard of a 2A3 with a 5 VAC Ef rating.  WHAT brand is it ??   ( AMP and Tube ) 

 

You know, for 100 years plus.... its been 2.5 VAC.  Every data sheet I have read. 

 

The 2.5 VAC Ef is one of the advantages of the 2A3 tube, because AC heating at 2.5 VAC sounds better than DC heating.

 

Educate me please !!  Thanks.

 

Jeffrey.  

 

 

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On 5/28/2019 at 7:54 AM, DjOverdose said:

i only have a small space for the speakers though. ive read somewhere that the reference are not that sensitive as advertised. 

 

 

 

  • How small is small, in cu.ft.?
  • How far away do you sit?
  • How loud do you like it, in dB, on loud passages?
  • Is your room live, medium, or dead?
  • Klipsch's sensitivity ratings are true in an average room with typical room and boundary gain (i.e., not out in the middle of the room, but very near a solid wall, or in a corner).  To convert to an anechoic rating, subtract 4 dB from the published rating; at least that's what a Klipsch employee said on the forum (about a year ago?).
  • Inside, in a room (forget about outside) each doubling of distance will cost you about 3 dB or so (not 6 dB!) this was a figure arrived at by PWK.  It is literally true (on the nose!) in my room.  So, if the RP 280Fs are against (or almost against) a wall, that would give you 98 dB at 1M at 1W, 95 dB at 2 M at 1W, and 92 dB at 4 M (about 13 feet) at 1W ... going back up, at 2 watts, we would have 95 dB/2W/at 13 feet.  That's enough for some people, but not others.  Klipsch considers that to be at the "loud" but not "very loud" level (Don Keele Jr., Dope from Hope V16, no1, January 1977).  As long as everything (all amplification) is working correctly, you would still get 1.5 watts more headroom.  Someone else may be able to tell you whether the RP 280F has any impedance anomalies that would be a problem.  I have noticed that some Klipsch speakers sound better with more power than they need, but there were covariates I didn't know how to account for.

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12 hours ago, Jeffrey D. Medwin said:

Thats highly unusual. 

 

That is because I was mistaken. It is 2.5 volts. mea culpa, mea culpa!

 

 

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On 7/1/2019 at 3:21 PM, garyrc said:
  • How small is small, in cu.ft.?
  • How far away do you sit?
  • How loud do you like it, in dB, on loud passages?
  • Is your room live, medium, or dead?
  • Klipsch's sensitivity ratings are true in an average room with typical room and boundary gain (i.e., not out in the middle of the room, but very near a solid wall, or in a corner).  To convert to an anechoic rating, subtract 4 dB from the published rating; at least that's what a Klipsch employee said on the forum (about a year ago?).
  • Inside, in a room (forget about outside) each doubling of distance will cost you about 3 dB or so (not 6 dB!) this was a figure arrived at by PWK.  It is literally true (on the nose!) in my room.  So, if the RP 280Fs are against (or almost against) a wall, that would give you 98 dB at 1M at 1W, 95 dB at 2 M at 1W, and 92 dB at 4 M (about 13 feet) at 1W ... going back up, at 2 watts, we would have 95 dB/2W/at 13 feet.  That's enough for some people, but not others.  Klipsch considers that to be at the "loud" but not "very loud" level (Don Keele Jr., Dope from Hope V16, no1, January 1977).  As long as everything (all amplification) is working correctly, you would still get 1.5 watts more headroom.  Someone else may be able to tell you whether the RP 280F has any impedance anomalies that would be a problem.  I have noticed that some Klipsch speakers sound better with more power than they need, but there were covariates I didn't know how to account for.

Hi Garyrc! 

 

i really dont know the exact size of the area. its a mix used room though, dinning, living room etc. i listen probably around 2M away from the speakers. Due to the limited space i have, my speakers are almost close to the wall. 

 

after reading your reply, I guess the 2A3 amp will be fine on powering the RP280f. 

 

hopefully My amp will be finished this week

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On 6/28/2019 at 6:01 PM, Schu said:

He's expecting 40w out of a 2a3?

nope... thats the model of the tubes. JJ 2a3 40W

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almost done. just waiting for the cage to be finished. the builder say its somewhere around 3.5WPC to 4WPC.

PicsArt_07-07-01.46.16.jpg

PicsArt_07-07-01.45.21.jpg

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The rectifier tube should located be as FAR away as possible, from the input tubes. 

 

Here, we see just the opposite, close-to and smack dab between both of the input tubes.

 

 

 

 

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I bet you can't wait to hear it fire up for the first time... you're going to be impressed and happy.

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