Sansui SP-150 Speakers : What power needed and amp style (SE vs PP)

[gug42]

Davis Stentaure : What power needed and amp style (SE vs PP)

Hello,

I have a pair of beautifull Sansui SP-150. My living room is around 15/20m².

So well can you help me to define my power needs and the amp style between :
1/ 25 Watts push-pull KT88
2/ 10 Watts SE 300B

For both I will use Lundhal output transformers, the standard version (probably ll1623 for both).

The spec of speaker :
Type: 3 way, 3 driver loudspeaker system
Frequency Response: 40Hz to 20kHz
Power Handling: 40WC
rossover Frequency: 700, 7000Hz
Impedance: 8Ω
Sensitivity: 98dB
Bass: 1 x 250mm cone
Midrange: 1 x 125mm cone
Tweeter: 1 x 50mm horn
Enclosure: bass reflex
Grille: hand carved Kumiko fretwork
Finish: oiled walnut
Dimensions: 607 x 367 x 303mmWeight: 17.5kg



Thank you in advance !

Regards,

 

[ethermion]

I sent a pair of SP-7500x to the dump not too long ago. You boxes look similar.

I seriously doubt they are of any merit, other than they can get loud.

If you are fussing about what tubes, what OT, you are on the wrong track. The speakers are nothing to be proud of. Flip 'em, and get something more real. Then come back to your original questions.

 

[Lingwendil]

They will work ~ok with a push pull amplifier of moderate power, so long as it has low enough output impedance (some negative feedback or plate to grid feedback should be fine) but will likely sound kind of muddy with SE.

15-20 watts should be plenty, triode connected KT88 with a smidge of global negative feedback would probably be fine, although it will be fancier than the speakers deserve, unless you've a special attachment to them (good garage speakers while doing car stuff, for instance) and just plain want to use them

 

[gug42]

Hello,

Thank you all for thoses honnests answer
Well I really like the look ... and the boxes are waf ... I know it doesn't make good speaker

Well I'm looking regulary to the second hand local market .... for klipsch heresy or klipsch forte. No luck since.

Cabasse are easier to find here ... but I'm always surprise by the low end frequency response ... lots of them are 60 Hz ... some are 50 and few at 40Hz ....

So for now, better time to build my high end headphones amp (second tube amplifier for me)

Thank you guys

 

[Wavebourn]

I would start from:
1.) Power needed for SPL that you want?
2.) Damping factor?
Then, I would think about what kind of music you prefer, and if it is a pop music, PP would be fine. If it is an audiophle quality, you should go with SE, despite of low efficiency. Then, according to power needed (1), I would select tubes. And according to damping factor (2), I would select topology.

 

[gug42]

Hello,

Hum well indeed, I will not listen at very loud level ... But I really care about the bass...

About speakers : I can't find easly Klipsch (forte II or KG) speakers here .... to bad ... In USA second hand are really accessible ... but not in europe ... harder to find

Any opinion about a pair of davis acoustic stentaure ?
STENTAURE LE - Davis Acoustics
40 Hz - 20 Khz
1x Tweeter : Horn Tweeter
2x Woofer : 17 cm (6.5″) paper cone
19 kg

I hope you are ok with my question .... a little offside but not too much ... ?

Thank you in advance !

 

[azazello]

With sensitivity of Your speakers, definitely SE 300B, that sounds definitely better PP KT88. IMO for you needs, better make 2 X 4 W SE 2A3, that s enought for Your room, be sure You dont use no more 2 X 1.5 W. PP KT is for speakers with low sensitivity, that start sound good from 10 W output power.

 

[kodabmx]

For those I would build a PP 6P3S amp of about 25W.

 

[gug42]

Hello,

Hard to say ... bass needes power, but well, indeed, my too powerfull headphone amps (around 3 watts on 8 ohms) are close to be enough .... but laking of bass ...

But for the davis, kodabmx you could be right with a 25 watts ...
For me, indeed pretty hard to says ... not enough experiences.

Thank you

 

[multi]

I think push pull KT88 's sound far better than SE 300B especially triode KT88, after all is a matter of opinion; I have never heard a SE300b amp that can play wide band classical music with good dynamics.

 

[Lingwendil]

SE is a waste of a good 300B if you expect it to provide decent bass response out of anything other than some physically large horns with very efficient drivers, been there, done that. Push pull AB1 or AB2 300B, tetrode connected 6L6, or a triode connected KT88 AB amplifier would be pretty much spot on if you want a good all-around amplifier capable of most anything you ask of it at that sort of power. Bass requires power and decent output impedance to sound accurate.

Leave poor performing SE to the golden ears that drink expired wine while listening to LPs by candlelight. That, or run a separate subwoofer

( I better board my windows, deadbolt my doors, and keep a rifle handy tonight, I fear what I spoke may be heresy to some of the members here! )

 

[gug42]

Hello,

Thank you, It seems that somes points goes in this direction ...

I tried to evaluate needed power with SPL and sensitivity .... but I'm really not comfortable to handle thoses data ...

- Let's start with with a SPL of : 80 dB
- I will be at 1,5 or 2m.
- Power peak seems to be at +10 or 20 dB from the average... so let's say 95 db @ 1,5 m
- Let's says my room is not treated ... so very little absorption, well so max 100 dB @ 1m
- With speaker of 95 dB / w / m, I need + 5 dB hum ... that's the point ... : to convert 5 dB in Watt ?!?

Ok I have read : to have +3 dB, the must be double. So for speaker with efficiency of 95 dB / W / m ... onyl two watts ?

And 80 dB SPL seems to be prety loud : Sound pressure - Wikipedia

Thank you in advance !

 

[azazello]

1-2 W from amp 3-4 W sounds better than 1-2 W from amp 30 W....except If You want to break the furniture, windows....

 

[gug42]

Well indeed for sure ... lot's of people says (and some on this thread), says that a SE 300B can't have good bass with thoses types of speaker (ie not high efficiency huge boxes).

I have done other calculation.

If I'd like to listen louder, well 85 dB SPL at the listen position. It could be 105 dB at one meter.

- With efficiency of 95 dB / W / m, I will need +10 dB. So 10 watts power.
- With efficiency of 90 dB / W / m, I will need +15 dB. So 30 watts power


More over, I have some doubt about the datasheets of the loudspeaker .... at least I doubt than the annonced efficiency could be for all frequencies ... from 20 Hz to 20 kHz ...

Did you think than Davis stentaure have 95 dB / W / m at 40 Hz with two 17cm woofers ?
And for the sansui, same question 98 dB / W / m at 40 Hz with the woofer and thoses boxes ?

And well is a "classical" 300B SE can really produce the needed powers at 40 Hz ? At least 5 Watts (10 watts will be better of course) at 40 Hz ?

Thank you in advance.

 

[Wavebourn]

1-2 W from amp 3-4 W sounds better than 1-2 W from amp 30 W....except If You want to break the furniture, windows....

Not at all, if you are listening to good recordings. You are right, if you play a solo guitar.

However, when you play highly compressed music, you do not need headroom, but what's the point in tube amps for such a music? Class D amps do it better.

More over, I have some doubt about the datasheets of the loudspeaker .... at least I doubt than the annonced efficiency could be for all frequencies ... from 20 Hz to 20 kHz ...

According to the graph on the datasheet above, your Sansui has -20 dB on 40 Hz. How much power do you need to boost 20 dB on 40 Hz?

 

[gug42]

Wavebourn, you are right ! Damm too much will be the answer .... So 30 Watts could not be enough ... and PP UL .... thx

Thank you evryone.

Regards,

 

[azazello]

Not at all, if you are listening to good recordings. You are right, if you play a solo guitar.

However, when you play highly compressed music, you do not need headroom, but what's the point in tube amps for such a music? Class D amps do it better.

Mmm, solo guitar sounds better on big power /You are musician/! But for good simph., string, soul, jazz music, IMO, is enough about 2 x 2 W - quality SE with good freeq. band is for listening for a much hours. And these Sansui have posibility for big bas sounding. High sensitivity speakers are for this goal! Small power for big rooms. Do people need big power, that never will use more 5-10 min and damage ears? /I have PP KT88 and SE 2A3 RCA and +++ are for second, acc. my frends opinion, but alwais I use 1 W SE EL11 Telefunken in triod with cool OTs, that is the best tube for all the times, IMO....I like SE, but this is another beer...PP is for breaking the sinks.../.
If You need a big power, You can make SE GU, GK,GM....Doesnt enough to be technician, can be meloman and audiophil!