The KT88 is 3 watts and the triple 6005 around 8+ watts.
300B Direct Couple SET Class A Design
- Thread starter Hari Iyer
- Start date
@yogibear I may probably not built the 6005 nor shall I go ahead with the 300B unless I am able to sell my current monoblocks.
If you still wish to compare the sonic of both amplifier you are welcome to do so with my similar topology KT88 monoblocks. JDM says that the 6005 beats the KT88 by 20%. This can give you a fair idea.
With high efficiency transducers, 1W or less is often enough for nominal listening levels. 3W should provide adequate reserve power.
If you want to hear something different, add a switch that will allow you to listen to SE KT88 in triode mode.
You might need more bias current in the final stage to get enough reserve power in triode mode.
There are some options without having to sell the SE KT88 amplifier or build something entirely new.
HB
I don't have any 300Bs to sell.i am sure you have not listened to any DC KT88 before.
Those look like chokes for an LSES filter, 330mH 1A.
10 ohms or less is "ultra-fi" per JDM.
Yes they are. DCR is 5.9 ohms. Use 24swg wire unlike Hammond. More rugged and better built quality compared to Hammond at 1/3 rd the cost.
This project now is currently on hold until April next year. Actually I do not have an order to build this, but is more for fun and learnings. After building them, they may eventually get sold - if at all to clear up living space. Anyone keen can pre- book.
grindstone
Active Member
There is almost nothing better than having spare chokes at hand in case of need (unless one has to move)...it's been a long time since they depreciated and only seem to appreciate these years 
Last week completed my single stage direct coupled, AC heated 300b amplifier driver stage design with EC91 tube. Operating voltage is 180vdc and operating current is 2mA. This will give me a voltage swing of 57volts and a voltage gain of 75 volts. The mu with this design stands at 90. Combined with the mu of the final tube gives a jump factor of 351 -a small fall from the magic number of 400. The plate dissipation of the finals is at 10.95watts.
This amp will start assembly after the completion of my ongoing 2a3 build project which is scheduled to be completed by March next year.
Thanks for looking.
This amp will start assembly after the completion of my ongoing 2a3 build project which is scheduled to be completed by March next year.
Thanks for looking.
I shall be looking for some adventure this month. I shall try and modify my current KT88 monoblocks to accommodate the 300B. For this i will need to change the Ea of the driver and the driver tube itself to EC91 (this is 7 pin). The 300B will be either my Shuguang 300B-98 or Psvance 300b-N after listening both. I have ordered a 5vac CT filament transformer for this duty. They will be AC heated. The direct couple voltage is calculated to be around 205vdc. Bias current is 48.5mA and grid bias around -37vdc. Plate dissipation i think is around 14.5watts. I have also ordered a 8pin to 4 pin adapter socket to save me from some mounting and removing work.
I am sure this will be a learning and fun.
I am sure this will be a learning and fun.
Last weekend, i was able to complete one channel of the 300B and its been singing ever since for an average of 4hrs every day. I have owned the Dared VP-300b for over 6 years which was a 3 stage, capacitor coupled, DC heated amplifier.
Now in my new experience the magic of 300b begins with a 2 stage (jump factor of 400), direct couple and AC heated filament. There is no looking back and this is going to be my final amplifier for sure. I had earlier contemplated building a 2a3 and now after listening to the 300b in its new Avatar i may probably skip that idea.
The 2a3 to my ears sound very dynamic, open and musical where as the 300b sounds very organic, lush, accurate and natural. Its a more of what your own preferences are and i may lean more towards accuracy than the euphonic sound of the 2a3.
Even between the 2 tubes Shuguaug 300b-98 and Psvane 300b-n mesh plate, i shall prefer the shuguang over the Psvane because they are more organic and natural. The Psvane may have more grit but in the long run i shall prefer more natural sound. The Shuguang would have completed at least 7000hrs and the Psvane around 300hrs.
Now in my new experience the magic of 300b begins with a 2 stage (jump factor of 400), direct couple and AC heated filament. There is no looking back and this is going to be my final amplifier for sure. I had earlier contemplated building a 2a3 and now after listening to the 300b in its new Avatar i may probably skip that idea.
The 2a3 to my ears sound very dynamic, open and musical where as the 300b sounds very organic, lush, accurate and natural. Its a more of what your own preferences are and i may lean more towards accuracy than the euphonic sound of the 2a3.
Even between the 2 tubes Shuguaug 300b-98 and Psvane 300b-n mesh plate, i shall prefer the shuguang over the Psvane because they are more organic and natural. The Psvane may have more grit but in the long run i shall prefer more natural sound. The Shuguang would have completed at least 7000hrs and the Psvane around 300hrs.
grindstone
Active Member
When you are already 2-stage direct-coupled with a quick supply and mesh plates, all that remains is only OPT quality & personal preferences IMO Sincere congrats, nice work Hari! Did you leave the other channel KT88 to run for a while or is everything torn-down?
Sincere congrats, nice work Hari! Did you leave the other channel KT88 to run for a while or is everything torn-down?The Other channel KT88 is still not torn down. I shall do an apple to apple comparison with the 300b tomorrow. I don't think it can outperform the 300Bs TBHWhen you are already 2-stage direct-coupled with a quick supply and mesh plates, all that remains is only OPT quality & personal preferences IMO
grindstone
Active Member
Good for you, man--I know you sounded pretty happy with what you already had so that's great. Credit to you for doing the exercise and following your own trail.
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