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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Need to find 300B tube amp use 6SN7 5U4G >25w/ch

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famousmockingbird

Member
Joined 2010
rongon said:
That's interesting.

Can the sweep tube work in triode at as high plate voltages as the 300B?
Click to expand...


Nope. That is one of their downsides. This particular tube has ~10 watts less plate dissipation compared to the 300b also:(

In triode mode I found that G2 voltage rating is pretty conservative and I had zero issues exceeding it, just mind the dissipation rating.

I don't require lots of power with my 104db/2.83v speakers. This tube works great at lower voltage and higher current. I am happy at Va-k=245, Ia=80mA, Vg1=-50

http://www.tubebooks.org/tubedata/we300a_b.pdf

Looking at the table on page 4;

Va=250 Rl=3k Vg=-52 Ia=40 Po=4watts


I get slightly more power but run much more current. Sounds good to me. If I had deeper pockets I would build a 300b amp but I don't so I settle for what I can afford. I get to be apart of the "SET" club sort of and enjoy the rich harmonic sonics just the same:)
 
S

supernut

Member
Joined 2012
Actually, I just want to make new system that fit my small bedroom. I listen to variaty type of music mostly pop (sometimes Jazz, Female voice, R&B)

My system in living room is solid state system A/B class I think (DAC Dual AK4399+Rotel RB 981 power amp + B&W DM603 S3 speakers). It is to big to fit my small bedroom and I want to enter tube integrated amp world. :)

I plan to purchase small speakers (Dali Zensor 3) which has SPL 108 DB which is very cheap in my country (THB 16,500) and find tube integrated amplifier to drive it (using same DAC dual AK4399 which I fond of)

So I found this 300B integrated amplifier 8W+8W that might suit to my small bedroom.

I am also found 6SN7 + KT88 (x2) but it is push pull 18W+18W.

here is the link:
https://world.taobao.com/item/17449807311.htm?spm=a312a.7700825.1997196601.39.vsezQD


I think 8W+8W is enough to drive 108 DBL. Many people in my country talk about good sound of 300B tube. So I am interested.

However, Chinese has 2 version of 6SN7 300B (420VDC & 7.3V) (320VDC & 6V)

I am not sure which one is better.
 
rongon

rongon

Member
Joined 2009
I plan to purchase small speakers (Dali Zensor 3) which has SPL 108 DB
Click to expand...

I think 8W+8W is enough to drive 108 DBL.
Click to expand...

Dali Zensor 3 speaker specifications claim 88dB sensitivity, which is still pretty high for a little bookshelf speaker.

It's listed as a 6 ohm speaker.

The manufacturer recommends amplifier power from 25 to 125 watts.

The problem in a small bedroom situation is not the power needed, rather it's whether the Dali Zensor 3 is an easy enough load for a single-ended 300B with no NFB to drive without sounding like it's asleep. If you've ever tried to drive B&W speakers with a single-ended flea-power amp, you'll know what I mean. A push-pull 300B amp would be a different story. That won't be a small amp, though.
 
S

supernut

Member
Joined 2012
Oh my mistake so my B&W DM603 S3 sensitivity is higher 90db than Dali Zensor 3. So B&W is little easier to drive than Dali Zensor 3.

Thank you so much for your information Mr.Rongon.

I have another alternative to purchase Acoustic Energy AE Aelite 1 which is 89DB

Piyanas


1. I never have Single end 300B. Therefore I never try drive B&W DM603 S3.
2. So I might need to change speaker to AE Aelite ?

Any bookshelf speakers that can drive by 8w+8W single end 300B?
 
K

Koonw

Disabled Account
Joined 2013
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K

Koonw

Disabled Account
Joined 2013
MC-550B (Class A PP)

MC-550B Class A push-pull amplifier
Circuit characteristics:
● use SRPP plus differential voltage amplification circuit for the front stage, so that the machine wide frequency response, low distortion, sound better.
● direct coupled preamp circuit for the whole structure and promote long-tail type inverter circuit.
● Class A push-pull power level is so low-frequency drivers foot, better sound quality.
● high-voltage delay start, can effectively extend the service life of the bile duct and VU meter for volume indication.
● output transformer silicon steel sheet imported from Japan, dedicated audio Z11 (0.35mm thick) and high-strength multi-layer oxygen-free copper wire and special winding process hierarchical grouping of production, so that the machine wide frequency response of 5Hz-73kHz (-2dB ) (according to national standard measuring method), to ensure the machine high, medium and low frequency sounds good, transparent and powerful.
● The machine used in all foreign famous factory audio special grade fever electrolytic capacitors, polarity Philips (MKP) capacitors and manufacture of high-quality gold resistance, the use of the main channel for imports large volume potentiometer with quiet background music, low noise, no coloration and durability advantages.

Electrical performance:
● Output Power: 18W + 18W (8Ω)
● Distortion: ≤0.42% (12W when)
● Frequency response: 5Hz -73kHz (-2dB)
● SNR: ≥82dB (A-weighted)
● load impedance: 4Ω - 8Ω
● Power Consumption: about 210W
● Input sensitivity: ≤0.22V
● Tube: 300B × 4 12AX7 × 2 12AU7 × 4
● Package weight: 30.0KG
● Voltage: 220 volts, for other voltages can be customized
 
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C

ColinA

Member
Joined 2005
Those Chinese claims always look fantastic.
The amplifiers are good to look at in pictures.

We have seen countless times that the performance claims are very over exaggerated and the quality control is abysmal.

You might get a gem, but a lot turn into a turd quite soon!

Yes I am biased, having one go up in flames in your living room will do that to you!
 
K

Koonw

Disabled Account
Joined 2013
A good one will cost more than 10k RMB. Most Chinese amp are for local market, you don't always get to pay agent for middleman cost at least, that would be enough to pay for upgrade esp. for whom know hows. It's not to say biased, you get what you paid for, it happens to every class of industries, some will buy with upgrade in mind, like tube rolling OP intended to do.
 
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