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Old 13th January 2003, 11:42 PM   #21
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Default 300B.

Hi,

In case you need more power and want stick with SE topology,I find this one appealing:

MACIEJ

Cheers,
__________________
Frank
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Old 14th January 2003, 01:41 AM   #22
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Quote:
Originally posted by dhaen
IMO A PP amplifier sounds closer to a Solid State amp. An SET will sound "warmer".
What sort of PP amp? A pentode/UL/Williamson arrangement with 20dB+ of feedback, or a proper 300B PP DHT like the Amity? If the first, then I agre to an extent. If the latter, then I don't at all (I have one running as I type, ie DHT, but not 300B), as it has all the good bits of a set, but actually has the frequency extremes and considerably more immunity to loads and PSU.
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Old 14th January 2003, 09:08 AM   #23
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Paul A. ,

Thank you. I read the pages you reffered to and the building instructions are very comprehensive. This is very important for me, just as using the 300B tube, so I'm almost convinced this is a suitable project for me.

The only remaining question is if the power will be enough for my proac response 2.5 diy. Their sensibility is 86 dB but they are a easy load as they don't go below 8ohm.
What kind of loudspekers do people use with the JE Labs 300? Have you heared that a low sensibility is OK if the impedance is not too low or that kind of similar information?

"...I'm sure you know that 10 watts is only 3dB less powerful than 20 watts...." If the difference is really this small, as dhean sais, I guess I don't have anything to worry about. My references are mostly differences between SS amps. But I know that tube power is much more "powerful" than SS power so I guess 9 W tube power can be quite a lot.

regards,
Per S
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Old 14th January 2003, 11:01 AM   #24
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World Audio Design do a PSE 300B kit. 20W

http://www.worldaudiodesign.co.uk/amplifiers.html
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Old 14th January 2003, 11:08 AM   #25
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Quote:
Originally posted by perka
"...I'm sure you know that 10 watts is only 3dB less powerful than 20 watts...." If the difference is really this small, as dhean sais, I guess I don't have anything to worry about. My references are mostly differences between SS amps. But I know that tube power is much more "powerful" than SS power so I guess 9 W tube power can be quite a lot.
Per, before you committ to building an amp that low in power, please either borrow one from someone and try it, or get an SPL meter, and see what sort of levels you actually have at your listening chair at the sort of levels you like.

A basic calculation:
ProAc = 86dB/1W/1m
8 watt amp = 9dBW ( dBW = 10 x log(amp power in W) )
subtotal = 95 dB SPL for 1 speaker
............. = 98 dB SPL for 2 speakers (approx,depends on room etc)
loss for 2.5m listening distance = 8dB

therefore peak SPL at the listening position is about 90dB (+/- a couple of dB) when the amp clips. At clipping, assuming that music has a peak/average ratio of around 20dB, your average level is a mere 70dB. IMO, this isn't enough power, unless your room is small, you sit close to the speakers and listen at low volumes to chamber music. Music always sounds more realistic when the system isn't clipping.

You might be happy with this situation, but before you shell out $$ on an experiment that may not work, find some way to measure the SPL at your chair, or try a similar amp.

One of the things amny people forget is the leading edge of the waveform is what we evolved listening to for survival, and lots of the information we take from any sound we hear is contained there. If your amp/speaker/room/listening position combo isn't able to produce these leading edges and peaks propely, music will sound compressed and lifeless, and your system no more than a glorifed Bose Waveradio. Of course your living arangements might dictate much lower levels but be sure, first. A 300B SE will not produce more than about 8W, and it's not like you have a "wattage" control on your amp, so after you build it, you just turn the knob and get 50W. It will undoubtedly require building a new amp.

Pro SPL calculator
http://www.doctorproaudio.com/doctor...n.htm#calc_spl

Cheers
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Old 14th January 2003, 12:33 PM   #26
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Brett, you do have point.
However I will not have the possibilty to borrow a 9W 300B and you are right, It's maybe then it's unwise not to be on the safe side and add some extra power - if your calculations are valid for the 300B. I know my proacs works very fine with 20W SE 300B, as I have listened to that. The sound level was even very strong.

dibblethwaite,

"...300B PSE Valve Monobloc Amplifier without valves - 875.00 (UK price) 745.00 (overseas price, exc. carriage)..."

If the price is for two monoblocks, I find it interesting. Also for me there is no duty from a european supplier.

Do you know something more about this amplifier. Do you know somebody who owns some of their amplifiers or the reputation of this firm?

Per S
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Old 14th January 2003, 01:05 PM   #27
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Have seen several people praising that company over at the audioasylum...
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Old 14th January 2003, 02:51 PM   #28
Joel is offline Joel  United States
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I would just ditch the 89dB speakers! Problem solved. Hell, then you can use any amp on the planet, and be happy.
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Old 14th January 2003, 03:24 PM   #29
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Quote:
Originally posted by Joel
I would just ditch the 89dB speakers! Problem solved. Hell, then you can use any amp on the planet, and be happy.
Yep. Trouble is, people get attached to the inefficient little squeezeboxes.

I'm running around 106dB and have 20W. No such thing as dynamic compression here. Or noise, or distortion.
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Old 14th January 2003, 03:31 PM   #30
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I think its more difficult to find a speaker that is close to your sound ideal than a amplifier that is close to the sound ideal and besides I have already heared them sound marvelous with a 20W so I won't follow your advice. And spending 5000usd for getting an efficient speaker (they start at that price if you don't build them yourself)? No.
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