I've seen this video before. There are many ways to amplify the signal before entering 300B. Personally I prefer a simple 2 stage amplification. I'll upload my schematic when I have access to my PC again.
<< All 300B amps are budget until you start spending money on Iron and fancy parts.
I much prefer the overall sound of the cheaper 2a3 if your speakers can accommodate it. Also easier to drive and B+ in the early 300V not 450V.
Not relevant to this thread, but there we are. I'm a big 2a3 fan. All my 300bs are back on the shelf.
I much prefer the overall sound of the cheaper 2a3 if your speakers can accommodate it. Also easier to drive and B+ in the early 300V not 450V.
Not relevant to this thread, but there we are. I'm a big 2a3 fan. All my 300bs are back on the shelf.
I'm sitting on the stash of 2a3 . Was going to make a clone of AN 300B PSE transformer coupled but in the meantime a pair of accessible AN P4 in distress came along so I'm deliberating using the iron to make 2a3 PSE (due to 1.3k C-core AN output tans) I blew the budget on P4 , don't have $1k to order AN parts and at east $700 on quad of basic 300B's (to preserve the value of AN amp otherwise it's just a lump of metal and acrylic face plate ) and I'm stuck with a pile of crap🙂 Being an idiot is a part and parcel of DIY efforts
<< I'm sitting on the stash of 2a3....
Your PSE 2a3 plan sounds excellent! You'll have a really good amp there. I guess use choke input for the PSU to bring the B+ down a bit and you're golden.
Your PSE 2a3 plan sounds excellent! You'll have a really good amp there. I guess use choke input for the PSU to bring the B+ down a bit and you're golden.
Beautiful!
Nothing wrong with lower power output, to get lower distortion and a higher damping factor (I saw the 5k mark on the output transformers).
One WE data sheet operating point has a 5k plate load, and 6.2 Watts output power with -30dBc 2nd harmonic distortion and -45dBc 3rd harmonic distortion @ 6.2 Watts.
6.2 Watts from the 300B tube to the output transformer primary, and 5.5 watts out of the transformer secondary, calculates to an output transformer with 0.5 dB Insertion loss.
When I designed and built SE 300B amplifiers, they only had 18 Watts in the plate. Cool, and long lasting.
On some WE 300B data sheets, the max dissipation is 40 watts, on other WE data sheets, it is 36 Watts.
6.25 Watts filament power. I loved my SE and PP mono-block amplifiers.
A typical 2A3 amplifier produces 4.2 Watts to the output transformer primary at 5% THD (-26dBc), mostly 2nd harmonic distortion.
A properly designed Parallel 2A3 SE, could get 8.4 Watts to the output transformer primary (@ 30Watts total plate dissipation).
8.4 Watts from the PSE to the output transformer, produces 7.5 Watts from the output transformer primary if the insertion loss is 0.5dB.
Total 12.5 Watts filament power on PSE. I loved my 2A3 SE and PP mono-block amplifiers.
Have fun listening!
P.S. I fondly remember Hong Kong and the New Territories several Decades ago.
Nothing wrong with lower power output, to get lower distortion and a higher damping factor (I saw the 5k mark on the output transformers).
One WE data sheet operating point has a 5k plate load, and 6.2 Watts output power with -30dBc 2nd harmonic distortion and -45dBc 3rd harmonic distortion @ 6.2 Watts.
6.2 Watts from the 300B tube to the output transformer primary, and 5.5 watts out of the transformer secondary, calculates to an output transformer with 0.5 dB Insertion loss.
When I designed and built SE 300B amplifiers, they only had 18 Watts in the plate. Cool, and long lasting.
On some WE 300B data sheets, the max dissipation is 40 watts, on other WE data sheets, it is 36 Watts.
6.25 Watts filament power. I loved my SE and PP mono-block amplifiers.
A typical 2A3 amplifier produces 4.2 Watts to the output transformer primary at 5% THD (-26dBc), mostly 2nd harmonic distortion.
A properly designed Parallel 2A3 SE, could get 8.4 Watts to the output transformer primary (@ 30Watts total plate dissipation).
8.4 Watts from the PSE to the output transformer, produces 7.5 Watts from the output transformer primary if the insertion loss is 0.5dB.
Total 12.5 Watts filament power on PSE. I loved my 2A3 SE and PP mono-block amplifiers.
Have fun listening!
P.S. I fondly remember Hong Kong and the New Territories several Decades ago.
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Here's the simple 2 stage amplication. The drawback is that you will need 2 coupling capacitors, which increases the overall cost.
No, it's not a commercial product.
The reasons I made it with PCB because:
1. it's idiot proof
2. easy to replicate (I made another pair for my friend)
3. only with PCB the power circuit is possible (~200pcs of components per block)
Thanks. The mark was unclear, actually it was 3.5k on the output transformer.
I chose the operating point as 300V plate voltage, -60V biase voltage, 60mA plate current and 3.5k load.
I'd say not just the 300B, but all tubes. Output transformers and coupling capacitors play an important role. BTW I am in love with the Jupiter copper foil beewax coupling capacitors from US.
They are little bit fragile , more so than Audio Notes . Electrocube 950 series of PP caps are really good . Too bad nobody sells them . Silver AN transformers are decent too🙂 . Western Electric tubes are not a hype either. Cheap components in hands of master trump fancy parts used by amateur every single time .
Masters usually are stingy..🙂.Maybe because it takes time to achieve the maestry.... Once you reach 70 the only thing that counts is money since your hearing starts to drop from 5kHz. This is the time to create mystique...Reality is a joint improves bass infinitely more than ScanSpeak woofer.
that's tre stage you need count the out is the standard ,is like jc morrison no good
you need at last 3 tube
This is a choice / some spend more money and use rectifier tubes for 300b singles. You must know that we have expensive tube rectifiers. This type of power supply does not have many parts. And it is not necessary use pcb. 300 b It is an amplifier for sound quality before targets such as making it comfortable and long tubes life.