The interstage is NC-20F made by ISO Transformers.
[It is the same as Tango NC-20F. As you know
Hirata Tango is no longer in business. The people
from Hirata made a company ISO Transformers,
they make old Hirata Tango models under the
name of ISO transformers.]
In any case, I would measure the frequency range of the speakers with that tube amp of yours, but also with some SS that has a small output impedance (in the order of milliohms). The simplest measuring program is Holmi Impulse (free software).
I tested a lot of Tango trafos, are very good of course.
But can you send the schematic of the amp?
Walter
And measure the output impedance of your amps. Like said, it’s quite likely the top end will come out exaggerated due to the high impedance of the speaker above 1kΩ.
Originally, the designer suggested me to choose between X-5S and X-10S.
X-5S is a 5kOhm transformer. He said X-10S has more primary
inductance (max 80H) and might produce better midrange, while X-5S
can produce more power and can potentially produce better bass.
The maximum power I can get with X-10S is about 35~40Watts per channel.
But, I felt 35Watts is enough for me.
I don't think it is real value ; how much is the THD?
With 5 K ohm as primary can be a right power but less DF and in a speaker as 800 a good DF is fine even with the tube you have a general low Damping factor
Walter
Of course. Linked thread is almost 10 years old, surely one of the most exciting ones, beside many others.
https://www.diyaudio.com/community/...ve-entries-due-by-oct-9th.279893/post-4482563
Come to think of it. By simply removing the bridge between HF and MF terminals one can disable the tweeters.
No easier test to find out if the mid or tweets are the culprit.
I don't know the THD of the amps.
By the way, I don't have a permission from the designer
to make the schematics available to others.
Overall, the schematics is like this.
The two triode sections of 12au7 are connected to form a SRPP.
There is a global negative feedback loop connected from the
speaker output terminal to the cathode bypass cap (which is
then connected to the ground through a 100ohm resistor).
The next stage is 6SN7. The two triode sections are connected
in parallel. The output of this stage is connected to NC20F
interstage transformer.
The output of the interstage is connected to another 6SN7 tube.
Again both inputs and outputs are connected in parallel.
The output of this 6SN7 tube is then connected to 211,
which are again connected in parallel.
I just don't hear harshness without tweeter.
It is not really like distortion or something.
I just hear more salient high frequency and slight less
mid-highs.
As many people mention, it may be due to my amps.
Might, but unlike other B&W's these speakers are very easy to drive.
I'm following with much interest 🙂
Thanks for the information.
There are so many thing I have to learn from now.
I find your advices are eye-opening to me.
I will study it soon because many people are
giving me advices now and I cannot swallow
everything at once.
It was a rhetorical question. 🙂 I was hoping to draw someone into the conversation who was familiar with doing the added compensation. Can you speculate on a CR, or LCR? I think 4uf and 12 ohms may be close, but it's important to be careful. Maybe a zma could be traced, and a filter verified.
As you said, I also thought treble should be muted a little bit.
At least the stereophile measurement says that and my hearing
also tells that. For that reason, I didn't try to measure the sound
even though I bought a small measuring mic (UMIK-1). I was not
actually sure how well the mic can measure and was not that
sure about my measuring ability. This is something not what I am
accustomed to.
In any case, this time I will also consider changing the crossover.
Making measurements is fun, but can be tricky at lower frequencies. Maybe practice with a small speaker until you get things working, and know your way around.
Dear WhiteDragon,
Many people are giving me great advices.
It is very difficult for me to sallow everything at once.
But, you are probably one of the very few who are
giving me the information I was originally seeking.
While it may turn out to be my amps that lead to
the prominent treble.
But, still I wish to try different tweeter because it is
not only the loudness of certain frequency region.
In any case, I am looking at the specs of the above
Dayton speakers.
RST28F:
- nominal 4ohms, DCR 3.0ohms,
- 93.5dB, Fs 775Hz
RST28A:
- nominal 4ohms, DCR 3.0ohms,
- 92.5dB, Fs 775Hz
Do you think I can use either of these
instead of stock tweeters by approprately
changing the crossover?
I was originally thinking about Satori Beryllium tweeter:
Satori TW29BN-B-8 (nominal 8ohms, DCR 6.2ohm, 93.5dB)
or Satori TW29BN-B (nominal 4ohms, DCR 3ohm, 95dB).
Would 92.5dB sensitivity or 93.5dB sensitivity be enough?
What I was worried about was the situation in which I will
have to reduce the gains of the midrange and the bass
because the volume of the new tweeter is too low.
So I first wanted to know whether I have to choose high
efficiency tweeter such as 95dB or higher or I can just go
with 93.5dB tweeter. Could you tell me the answer
if you know it from your experience?