I read in a book that 2:1 is ok, as long as also the power supply is 2:1 , able to deliver the current/voltage in the bass without flinching much. IDK how feedback is going to help, I suppose it does.
Question: do you know how a solid state pp stage reacts to 'real' loudspeakers, with the feedback induced low outputZ?
Is the rational diy way is to design from upstream to downstream, finalizing the system by measuring the drivers impedance in real life in the box with the combination of the driving amplifier, then designing an XO which resolve the issues specific to an imperfect amplifier ...
I haved used at 60 and 70ma with good bass ,with 5k load no problem
Last edited:
It is possible to use a LL1682 S.E. with 300B, at 100ma. 17H, or it is better to use it at 50ma 35H, I'm looking for something cheap OPT, but performing to do some comparative tests, The driver will be a 6EM7 coupled in RC or LC.
There may be an alternative from other brands...........
There may be an alternative from other brands...........
You can calculate this easily with the tube plate resistance and the inductance, it gives you the -3db approximate point with the formula. and why would you push the bias to 100ma? Usually you keep it to 70ma for such a costly tube...
You could use EL34 to save money, but keep the high quality OT! You will not regret having the best OT possible, trust me!
You could use EL34 to save money, but keep the high quality OT! You will not regret having the best OT possible, trust me!
You are in Italy
Ask to Onori or Piemme or Fiat for a good Ot
The cheap OT for 300B is not a good start point
In Italy there is a phrase
Vuoi la botte piena e la moglie ubriaca
Mean
You want a full barrel and the wife drunk
Walter
What you tell me is absolutely correct, but to test on a new 300B amp, I didn't want to disassemble my old power amp. Regarding the Italian winders, I think they have all copied and wrongly from something known, if you have to faithfully reproduce OPT Hashimoto in Italy, it will cost as much as original in Japan or maybe more.....
Roberto
Roberto
The main problem od these graph is the limited info about Zsource and level
And the indication of inductance is not referred.
At 20Hz the Z is 1k5 ohm (2k5 point), so it will be poor for 300B even for 3k5 is not so high at low freq. as shown in the graph.
I haven't doubt about the quality of Hasimoto but these datas are limited.
Last, why I have to use a OT where, in case, I leave a part of primary "on the fly" ?
Much better the H30-3.5S
And the indication of inductance is not referred.
At 20Hz the Z is 1k5 ohm (2k5 point), so it will be poor for 300B even for 3k5 is not so high at low freq. as shown in the graph.
I haven't doubt about the quality of Hasimoto but these datas are limited.
Last, why I have to use a OT where, in case, I leave a part of primary "on the fly" ?
Much better the H30-3.5S
300B is some of the most non-linear triode out there
Plus, with 3.5k/8ohm ratio with 700ohm Rp, the output R is not low enough.
You will get 5 watts out of the design.
If you used a 4.5k yeah, maybe try with low power and high THD.
It depends of your objective for sound, or just build the best amplifier you could with a 300B tube
Plus, with 3.5k/8ohm ratio with 700ohm Rp, the output R is not low enough.
You will get 5 watts out of the design.
If you used a 4.5k yeah, maybe try with low power and high THD.
It depends of your objective for sound, or just build the best amplifier you could with a 300B tube
I don't know Fiat, but I agree on Piemme (the owner is as good as his products) and Onori (a bigger reality, but very good products as well).
Piemme has generally better prices than Onori, IME.
Both of them I'm sure they have not copied, but developed their own transformers.
Please, before writing something similar without any proven fact, think deeply.
Piemme has generally better prices than Onori, IME.
Both of them I'm sure they have not copied, but developed their own transformers.
Please, before writing something similar without any proven fact, think deeply.
Really? Low quality/untested stuff maybe is not great. That can happen as there are and there have been many copies......
If the 300B were one of the most non-linear triodes, most tubes would be just garbage. This is not case.
Anything between 3.5 and 5K can work just fine. They only require a bit different approach. One can get 6-7 W at 1% THD in both cases without using feedback. If that is high distortion then I think you are in the wrong place.
The difference in damping factor has very little relevance in practice, in the best case.