2 x 1000 watts tube amplifier - UK Vintage Radio Repair and Restoration Discussion Forum

brunel · 11th Mar 2011, 9:58 am

http://www.elektor.com/news/it-s-ali..._campaign=news

http://www.youtube.com/watch?v=btSg2...layer_embedded

Tractorfan · 11th Mar 2011, 10:37 am

Hi,
This amp was mentioned on here a while ago. Very impressive! Although I'm puzzled by the "2 x 1000" tag as this is a mono PA amp with a push-pull o/p. Isn't it?
Just imagine TWO of them sitting in the lounge either side of your stereo set up. I'm sure the street lights would dim on the loud bits

Cheers, Pete

Skywave · 11th Mar 2011, 5:47 pm

Yup - you'd notice the dimmed street lights for sure when you responded to the hammering on the front door to discover your neighbours standing there & looking very angry!

Al.

HamishBoxer · 11th Mar 2011, 5:50 pm

What are the output valves?

David

11th Mar 2011, 5:53 pm

These! http://www.diyaudio.com/forums/tubes...amplifier.html

yestertech · 11th Mar 2011, 5:53 pm

What ?
No Bowden cables or valves at funny angles ?

Andy

HamishBoxer · 11th Mar 2011, 6:09 pm

Thanks for the valve info,some beasties to say the least.

David

Peter.N. · 11th Mar 2011, 6:25 pm

Very impressive, built like WD equipment and I like all the luminescence, sounds good too - as far as I can tell through a 2 watt computer speaker!

Peter

Phil G4SPZ · 11th Mar 2011, 11:31 pm

These various threads on mega-power audio amplifiers remind me of the article by George Izzard O'Veering published in Wireless World many years ago... although it describes a transistor amplifier, it should hopefully raise a chuckle from those who haven't seen it before.

http://sound.westhost.com/dynamic-range.htm

Peter.N. · 12th Mar 2011, 1:16 am

The bit about the power necessary strikes a chord (no pun intended) the output of the average valve radio is probably in the range of 1 - 3 watts and yet they could still be uncomfortably loud in the average room.

Peter

ppppenguin · 12th Mar 2011, 8:15 am

There's an interesting psycho-acoustic point here. At a given (acoustic) power level distorted sound seems louder than undistorted sound. Acoustic power depends on the efficiency of the speaker and will typically be a small fraction of the amplifier power. On a very small scale I have processed a couple of bits of music to use as ring tones. I used Audacity to deliberately push the sound into clipping. Sounded horrible on the computer speakers but gave better audibility on a tiny mobile phone where fidelity is not important.

On the subject of vintage radios sounding loud on a few watts there's another relevant point. In many cases the speaker efficiency will be a lot higher in a vintage radio than in hifi speakers so you get more for your electrical watts.

Phil G4SPZ · 12th Mar 2011, 10:37 am

I can readily accept that the Philips valve amplifier delivers a kilowatt, on a continuous RMS basis. However, 20 or 30kW in a car is stretching credulity, requiring not only the dissipation of something approaching 40kW of heat within the vehicle, but requiring (by my arithmetic) over 3,000 amps at 12 volts...

One has to assume that such high power ratings are derived from the sum of the amplifier manufacturers' quoted outputs, not measured RMS output on a continuous basis.

audiomik · 12th Mar 2011, 3:50 pm

have found a link to the EL6471 Service manual here:
http://83.117.57.34/nvhr/Philips_EL6471.pdf

Interesting circuitry, with only 2 valves in the output stage!
Mik

MrElectronicman · 12th Mar 2011, 5:13 pm

Phil G4SPZ echoed my thoughts exactly

dennishoy · 12th Mar 2011, 10:00 pm

'You could toast your bread with the heat they kick out'. Says it all really.... the power is in the valve losses and not in audio power. The design is very inefficient and unsuitable for the average home.

The problem with HiFi is that there are plenty of idiots with more money than electronics knowledge and common sense. Who honestly believes that a 13Amp mains plug with gold-plated pins gives a better sound? Likewise, speaker cable with oxygen-free copper conductors. The HiFi magazines are partly to blame here, often providing a good performance write-up on something that clearly will make no difference. The companies must be paying the magazines to hype-up the so-called 'product'.
A fool and his money are easily parted - never been more true in the world of HiFi.

Tractorfan · 13th Mar 2011, 12:48 pm

Hi,
I've just been having a look at the schematic PDF to see if I had enough bits in my junk box to build one (I've got two EL34s and a couple of fuse holders, that's it

), and I've noticed that the cathodes of the EL34s appear to be strapped to their heaters thus shorting the two cathodes together. Got to be a slip of the draughtsman's pen surely? I thought it might have been something to do with heater cathode insulation, but the two heaters are fed from the same source (same reference letters).
Cheers, Pete

audiomik · 13th Mar 2011, 5:50 pm

Tractorfan
seems that they corrected this Heater Cathode linking to the same heater Supply in the revised Circuit on page 26 of the pdf....

Anyway, also managed to find a datasheet for the QB3.5-750 Output Valves:
http://www.abex.co.uk/sales/highvolt.../qb3.5-750.pdf

And a bit more searching on the same site turned up this

:
http://www.abex.co.uk/sales/highvoltage/other/182/
A "Royal Navy Type 182 Final Amplifier and Power Unit"
Quote: "With modification, these amplifiers could form the basis of a high power RF amplifier for frequencies up to 75MHz, or beyond.
For the High Voltage & High Energy experimenter, these units contain many useful parts. See photographs and descriptions of the components used in these units.
Once stripped, these components may be re-used for a wide variety of applications"

A possible source of suitable parts perhaps?

Just to be clear I've no connection to Abex - merely found their website by chance whilst searching for the Valve data.
Mik

11th Mar 2011, 9:58 am	#1
brunel Heptode Join Date: Sep 2005 Location: LEEDS.......North of the River Aire. Posts: 872	2 x 1000 watts tube amplifier http://www.elektor.com/news/it-s-ali..._campaign=news http://www.youtube.com/watch?v=btSg2...layer_embedded Last edited by brunel; 11th Mar 2011 at 10:03 am.

11th Mar 2011, 10:37 am	#2
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,183	Re: 2 x 1000 watts tube amplifier Hi, This amp was mentioned on here a while ago. Very impressive! Although I'm puzzled by the "2 x 1000" tag as this is a mono PA amp with a push-pull o/p. Isn't it? Just imagine TWO of them sitting in the lounge either side of your stereo set up. I'm sure the street lights would dim on the loud bits Cheers, Pete __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

11th Mar 2011, 5:47 pm	#3
Skywave Rest in Peace Join Date: Jun 2006 Location: Chard, South Somerset, UK. Posts: 7,457	Re: 2 x 1000 watts tube amplifier Yup - you'd notice the dimmed street lights for sure when you responded to the hammering on the front door to discover your neighbours standing there & looking very angry! Al.

11th Mar 2011, 5:50 pm	#4
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: 2 x 1000 watts tube amplifier What are the output valves? David

11th Mar 2011, 5:53 pm	#5
Guest Guest Posts: n/a	Re: 2 x 1000 watts tube amplifier These! http://www.diyaudio.com/forums/tubes...amplifier.html

11th Mar 2011, 5:53 pm	#6
yestertech Nonode Join Date: Dec 2002 Location: Coulsdon, Surrey, UK. Posts: 2,130	Re: 2 x 1000 watts tube amplifier What ? No Bowden cables or valves at funny angles ? Andy

11th Mar 2011, 6:09 pm	#7
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: 2 x 1000 watts tube amplifier Thanks for the valve info,some beasties to say the least. David

11th Mar 2011, 6:25 pm	#8
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: 2 x 1000 watts tube amplifier Very impressive, built like WD equipment and I like all the luminescence, sounds good too - as far as I can tell through a 2 watt computer speaker! Peter

11th Mar 2011, 11:31 pm	#9
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Re: 2 x 1000 watts tube amplifier These various threads on mega-power audio amplifiers remind me of the article by George Izzard O'Veering published in Wireless World many years ago... although it describes a transistor amplifier, it should hopefully raise a chuckle from those who haven't seen it before. http://sound.westhost.com/dynamic-range.htm __________________ Phil Optimist [n]: One who is not in possession of the full facts

12th Mar 2011, 1:16 am	#10
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: 2 x 1000 watts tube amplifier The bit about the power necessary strikes a chord (no pun intended) the output of the average valve radio is probably in the range of 1 - 3 watts and yet they could still be uncomfortably loud in the average room. Peter

12th Mar 2011, 8:15 am	#11
ppppenguin Retired Dormant Member Join Date: Dec 2003 Location: North London, UK. Posts: 6,168	Re: 2 x 1000 watts tube amplifier There's an interesting psycho-acoustic point here. At a given (acoustic) power level distorted sound seems louder than undistorted sound. Acoustic power depends on the efficiency of the speaker and will typically be a small fraction of the amplifier power. On a very small scale I have processed a couple of bits of music to use as ring tones. I used Audacity to deliberately push the sound into clipping. Sounded horrible on the computer speakers but gave better audibility on a tiny mobile phone where fidelity is not important. On the subject of vintage radios sounding loud on a few watts there's another relevant point. In many cases the speaker efficiency will be a lot higher in a vintage radio than in hifi speakers so you get more for your electrical watts.

12th Mar 2011, 10:37 am	#12
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Re: 2 x 1000 watts tube amplifier I can readily accept that the Philips valve amplifier delivers a kilowatt, on a continuous RMS basis. However, 20 or 30kW in a car is stretching credulity, requiring not only the dissipation of something approaching 40kW of heat within the vehicle, but requiring (by my arithmetic) over 3,000 amps at 12 volts... One has to assume that such high power ratings are derived from the sum of the amplifier manufacturers' quoted outputs, not measured RMS output on a continuous basis. __________________ Phil Optimist [n]: One who is not in possession of the full facts

12th Mar 2011, 3:50 pm	#13
audiomik Retired Dormant Member Join Date: Oct 2010 Location: Bath, Somerset, UK. Posts: 96	Re: 2 x 1000 watts tube amplifier have found a link to the EL6471 Service manual here: http://83.117.57.34/nvhr/Philips_EL6471.pdf Interesting circuitry, with only 2 valves in the output stage! Mik

12th Mar 2011, 5:13 pm	#14
MrElectronicman Heptode Join Date: Feb 2011 Location: Washington DC, USA Posts: 619	Re: 2 x 1000 watts tube amplifier Phil G4SPZ echoed my thoughts exactly

12th Mar 2011, 10:00 pm	#15
dennishoy Retired Dormant Member Join Date: Nov 2010 Location: Hampshire, UK. Posts: 167	Re: 2 x 1000 watts tube amplifier 'You could toast your bread with the heat they kick out'. Says it all really.... the power is in the valve losses and not in audio power. The design is very inefficient and unsuitable for the average home. The problem with HiFi is that there are plenty of idiots with more money than electronics knowledge and common sense. Who honestly believes that a 13Amp mains plug with gold-plated pins gives a better sound? Likewise, speaker cable with oxygen-free copper conductors. The HiFi magazines are partly to blame here, often providing a good performance write-up on something that clearly will make no difference. The companies must be paying the magazines to hype-up the so-called 'product'. A fool and his money are easily parted - never been more true in the world of HiFi.

13th Mar 2011, 12:48 pm	#16
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,183	Re: 2 x 1000 watts tube amplifier Hi, I've just been having a look at the schematic PDF to see if I had enough bits in my junk box to build one (I've got two EL34s and a couple of fuse holders, that's it ), and I've noticed that the cathodes of the EL34s appear to be strapped to their heaters thus shorting the two cathodes together. Got to be a slip of the draughtsman's pen surely? I thought it might have been something to do with heater cathode insulation, but the two heaters are fed from the same source (same reference letters). Cheers, Pete __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

13th Mar 2011, 5:50 pm	#17
audiomik Retired Dormant Member Join Date: Oct 2010 Location: Bath, Somerset, UK. Posts: 96	Re: 2 x 1000 watts tube amplifier Tractorfan seems that they corrected this Heater Cathode linking to the same heater Supply in the revised Circuit on page 26 of the pdf.... Anyway, also managed to find a datasheet for the QB3.5-750 Output Valves: http://www.abex.co.uk/sales/highvolt.../qb3.5-750.pdf And a bit more searching on the same site turned up this: http://www.abex.co.uk/sales/highvoltage/other/182/ A "Royal Navy Type 182 Final Amplifier and Power Unit" Quote: "With modification, these amplifiers could form the basis of a high power RF amplifier for frequencies up to 75MHz, or beyond. For the High Voltage & High Energy experimenter, these units contain many useful parts. See photographs and descriptions of the components used in these units. Once stripped, these components may be re-used for a wide variety of applications" A possible source of suitable parts perhaps? Just to be clear I've no connection to Abex - merely found their website by chance whilst searching for the Valve data. Mik