A decent tube amp? "Worldwide 300B Builders" - Electronic Circuits Projects Diagrams Free

blueroomelectronics · 5th July 2008, 01:08 AM

Creatron Inc now sells vacuum tubes and the owner Lawrence carries was looking for a good tube amp / preamp to make into kit form. Tubes are NOT my forte but I was Googling and came across this site. Some really nice looking project photos.

http://www.iol.ie/~waltonaudio/worldbuilders.html

audioguru · 5th July 2008, 02:18 AM

I made a Heathkit tube amp in about 1961. It sounded good when new then got bad.
I took it to a Macintosh Amplifier Clinic and they showed 12% distortion at only half its rated power. I replaced its output TOOBS and had it retested and it was powerful with low distortion. The distortion retuned in a few months.
TOOBS WEAR OUT!

My tube amplifier was Hi-Fi. It didn;t have the high second harmonic distortion of guitar amps.

You can buy very expensive amps with glowing tubes on top. The tubes are for show and are not part of the amp's circuit.

Mikebits · 5th July 2008, 02:23 AM

Yeah it seems as though tubes have been revived as Rock guitarist seem to prefer the sound of a good tube amp. I saw a site where the PA tubes sold for like $300. per amp in a pushpull configuration.

Fender GT6550 Tube Tubes at Music123.

speakerguy79 · 5th July 2008, 02:28 AM

Don't they still use tubes for radio transmitters?

Mikebits · 5th July 2008, 02:43 AM

Quote:

Originally Posted by speakerguy79

Don't they still use tubes for radio transmitters?

Prey tell, why would they? Semiconductors can produce mucho power these days, without the high fail rates of tube devices.

I suppose some old Ham types might just build one to be nostalgic.

audioguru · 5th July 2008, 03:09 AM

There are some huge vacuum tubes made for radio transmitters. Semiconductors can't stand 100kW and more with thousands of volts with hundreds of amps at RF.

**3v0** · 5th July 2008, 03:34 AM

Back in the late 80's I heard talk about an amp that HP engineers had developed for their personal use. The plans were passed from division to division. It was said to to better then anything you could buy but I do not have a clue where to go to find them.

Mikebits · 5th July 2008, 04:18 AM

Well I must confess I was thinking 1KW type transmitters. I really never thought about larger ones. Back in my Navy days, we had a 40KW magnetron that was water cooled. Quite a large setup.

Mikebits · 5th July 2008, 07:19 AM

200 KW solid state.
http://www.broadcast.harris.com/prod...edia/dx200.pdf

**Nigel Goodwin** · 5th July 2008, 09:09 AM

I agree with the rest, I come from the valve/tube days, and it makes me laugh what people will pay for high distortion, high noise, and poor bandwidth these days

Where valvew amps are usful is guitar amps, because many guitarists are looking for that specific highly distorted sound - but far more actually use transistor amps, and even the valve amp fans often use transistor amps in the recording studio.

What you must NEVER do is run a transistor amp into clipping, as they sound really horrible.

speakerguy79 · 5th July 2008, 03:57 PM

They also fall over themselves to get Allen Bradley carbon comp resistors. The one thing I don't want is something that a) dries out and b) has "voltage coefficients of [insert anything]".

CynicalMan · 5th July 2008, 04:24 PM

Quote:

Originally Posted by Nigel Goodwin

What you must NEVER do is run a transistor amp into clipping, as they sound really horrible.

There are some decent solid state amps that can distort just fine.

Clipping opamps sound like crap.

crutschow · 5th July 2008, 04:56 PM

Quote:

Originally Posted by speakerguy79

They also fall over themselves to get Allen Bradley carbon comp resistors. The one thing I don't want is something that a) dries out and b) has "voltage coefficients of [insert anything]".

Plus excess noise from any dc current (unlike pure metal resistors which only have thermal noise).

**Nigel Goodwin** · 5th July 2008, 05:49 PM

Quote:

Originally Posted by CynicalMan

There are some decent solid state amps that can distort just fine.

They would have to be specifically designed to clip, more an overdrive circuit than clipping the amplifier - it's usually done with clipping diodes in the preamp, and not by driving the output stage past the power rails!

Centretek · 6th July 2008, 02:01 PM

Valve amps are inherently better sounding because they don't generate odd harmonics like semiconductor devices because of the difference in inter-electrode capacitance.
As a youngster we made guitar amps with 120W RMS outputs from 6DQ6 s in push-pull.
These tubes were used in BW TV sets for the horizontal outputs.

If your valve amp kept degrading tubes then their heaters were being run to hot. Some valves had the cathode material coated onto the heater wires and it got depleted by excessive heat. The heater voltage should be 6.3V AC and NEVER higher than 7 Volts.
The anode plates of an audio valve should NEVER glow.

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5th July 2008, 01:08 AM	(permalink)
blueroomelectronics	A decent tube amp? "Worldwide 300B Builders" Creatron Inc now sells vacuum tubes and the owner Lawrence carries was looking for a good tube amp / preamp to make into kit form. Tubes are NOT my forte but I was Googling and came across this site. Some really nice looking project photos. http://www.iol.ie/~waltonaudio/worldbuilders.html __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com

5th July 2008, 02:18 AM	(permalink)
audioguru	I made a Heathkit tube amp in about 1961. It sounded good when new then got bad. I took it to a Macintosh Amplifier Clinic and they showed 12% distortion at only half its rated power. I replaced its output TOOBS and had it retested and it was powerful with low distortion. The distortion retuned in a few months. TOOBS WEAR OUT! My tube amplifier was Hi-Fi. It didn;t have the high second harmonic distortion of guitar amps. You can buy very expensive amps with glowing tubes on top. The tubes are for show and are not part of the amp's circuit. __________________ Uncle $crooge

5th July 2008, 02:23 AM	(permalink)
Mikebits	Yeah it seems as though tubes have been revived as Rock guitarist seem to prefer the sound of a good tube amp. I saw a site where the PA tubes sold for like $300. per amp in a pushpull configuration. Fender GT6550 Tube Tubes at Music123.

5th July 2008, 02:28 AM	(permalink)
speakerguy79	Don't they still use tubes for radio transmitters?

5th July 2008, 03:09 AM	(permalink)
audioguru	There are some huge vacuum tubes made for radio transmitters. Semiconductors can't stand 100kW and more with thousands of volts with hundreds of amps at RF. __________________ Uncle $crooge

5th July 2008, 03:34 AM	(permalink)
3v0	Back in the late 80's I heard talk about an amp that HP engineers had developed for their personal use. The plans were passed from division to division. It was said to to better then anything you could buy but I do not have a clue where to go to find them. __________________ search engine for electronic parts Junebug USB PIC programmer kit., USB Bit Wacker, Homepage The 15 Minute Printed Circuit Board! (+drill time)

5th July 2008, 04:18 AM	(permalink)
Mikebits	Well I must confess I was thinking 1KW type transmitters. I really never thought about larger ones. Back in my Navy days, we had a 40KW magnetron that was water cooled. Quite a large setup.

5th July 2008, 07:19 AM	(permalink)
Mikebits	200 KW solid state. http://www.broadcast.harris.com/prod...edia/dx200.pdf

5th July 2008, 09:09 AM	(permalink)
Nigel Goodwin	I agree with the rest, I come from the valve/tube days, and it makes me laugh what people will pay for high distortion, high noise, and poor bandwidth these days Where valvew amps are usful is guitar amps, because many guitarists are looking for that specific highly distorted sound - but far more actually use transistor amps, and even the valve amp fans often use transistor amps in the recording studio. What you must NEVER do is run a transistor amp into clipping, as they sound really horrible. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

5th July 2008, 03:57 PM	(permalink)
speakerguy79	They also fall over themselves to get Allen Bradley carbon comp resistors. The one thing I don't want is something that a) dries out and b) has "voltage coefficients of [insert anything]". Last edited by speakerguy79; 5th July 2008 at 03:58 PM.

6th July 2008, 02:01 PM	(permalink)
Centretek	Valve amps are inherently better sounding because they don't generate odd harmonics like semiconductor devices because of the difference in inter-electrode capacitance. As a youngster we made guitar amps with 120W RMS outputs from 6DQ6 s in push-pull. These tubes were used in BW TV sets for the horizontal outputs. If your valve amp kept degrading tubes then their heaters were being run to hot. Some valves had the cathode material coated onto the heater wires and it got depleted by excessive heat. The heater voltage should be 6.3V AC and NEVER higher than 7 Volts. The anode plates of an audio valve should NEVER glow. __________________ A conclusion, is the point reached when you stop thinking.