Are you sure?

[Rednaxela]

Lol.

 

[egellings]

Here is my tube amp home brewed setup:

View attachment 281237

The preamp I even named! "His Reference!". I did not skimp in the iron. All transformers are made by me on a coil winder I share with a partner in tube amp crime, who has recently passed away, sadly. I might have gotten carried away with all the iron, but, I like my iron!

The 5 little buttons in the middle of the preamp's front panel are capacitive touch switches made by a now defunct company called Centrlab (<CRL>). I worked for that company which got bought by North American Philips, and later by Bourns, Inc, the Trimpot (TM) people. The buttons are thick film ceramic momentary contact open collector switches and were branded as "Magic Dot", so there is circuitry around them that latches a touched button's reed relay on until another button is touched. A little red LED built into each switch indicates an 'ON' condition. The touched section of the switch is actually a cermet resistor on an alumina ceramic substate. Left 4 buttons select inputs, (PHONO, Line1, Line 2, Line3) while the rightmost button is a touch-on / touch off one that acts like a tape monitor switch. There is an Rdelay generator built into the control circuit that ensures that a currently energized reed relay has more than enough time (about 50mSec) to open before the newly selected one closes, so there is no chance of two inputs being momentary shorted together during input changes. I have a couple of spares should one of the switches fail. After 21 years of regular use none have failed so far. I'm on my 2nd set of tubes. The handles and industrial looking knobs give the preamp a serious look, as in, " I ain't here to look purdy; I'm here to play fuh-baw!". Reed relays are C.P. Clare 1A12, and they have metal cases that are grounded so that there is no crosstalk between adjacent relays. The preamp is a phono stage and a line stage, using 12 vacuum tubes. Top box is the preamp proper, and the bottom box is power supply & housekeeping. Heaters are fed with slow turn-on DC to prevent current turn-on surges, and regulated 310Vdc plate voltage comes on slowly after tubes have had time to come to full heater brightness. A normally closed contact anti-thump relay shorts the output to ground when the preamp is off and un-shorts it after everything settles down after turn-on. When the preamp is powered down, the relay driver circuit immediately deactivates the output relays (within 2 cycles of 60Hz AC) so that the outputs are shorted to ground before the regulated supply drops out of regulation and generates a nasty woofer-blowing thump. All this effort resulted in a very polite preamp that never surprises me when I am careless with my system power UP/DOWN sequence. Oh, and it sounds good and is quiet. The only AC in the preamp box is the music signal.

 

[Yasuo]

I'm not sure about anything...

 

[Tassin]

I'm not even sure I know what to be so sure about ...

 

[Timcognito]

 

[Rednaxela]

 

[computer-audiophile]

The preamp is a phono stage and a line stage, using 12 vacuum tubes.

Interesting. What is the total count of tubes per channel in this setup?

I have a completely different design philosophy. I don't have input selectors and such. Minimalism rules and ensures an extremely short and clean signal path. My current amplifier chain from phono cartridge to speaker has only 4 true triodes per channel.

 

[egellings]

Interesting. What is the total count of tubes per channel in this setup?

I have a completely different design philosophy. I don't have input selectors and such. Minimalism rules and ensures an extremely short and clean signal path. My current amplifier chain from phono cartridge to speaker has only 4 true triodes per channel.

View attachment 282386

Nice setup! The 12 tubes in my home brewed preamp are duo-triodes, 6922/6DJ8. This pre was my all-out effort, 'nothing's too good for my little Fi-fi' audio extravaganza attempt. In all the tubes except for one in the line stage, the two triodes in each tube are paralleled, resulting in one larger triode per tube. Each phono stage channel uses 4 of these composite triodes, and the line stages each use 1 of them plus the unparalleled tube. The phono stage has an input triode followed by a cascode of 2 more, and the cascode is buffered by a constant current-sunk cathode follower stage for good drive capability. A cascode is a stage in which two triodes (or other amplifying devices) are stacked one on top of the other, rather than in series as they would be in so-called cascade or series connection. Phono stage places the RIAA EQ network in the feedback loop. Since a lot of gain is needed at 20Hz relative to 1kHz, the cascode and the lone triode stage together provide the necessary open loop gain so that the pre does not run out of steam, gain-wise, at 20 Hz, where 10X more amplification is needed relative to 1kHz. So that's where 8 of the little tubes went, 4 per side. The line stage is just a two-stage one with one 6922 providing two stages of amplification, and this is buffered by another constant current sunk cathode follower. It uses negative feedback. B+ is a regulated 310Vdc, and heaters are provided by slowly rising DC at turn-on as well. B+ comes on after tubes have warmed up after turn-on. In general, it has been reliable since the tubes are gently handled by the circuits they're in. The preamp is still going strong after 21 years' use and is on its second set of tubes. I see no need to replace it. The preamp is a two box one with an umbilical cable using connectors of many pins to connect them together.

 

[computer-audiophile]

Nice setup! The 12 tubes in my home brewed preamp are duo-triodes, 6922/6DJ8. This pre was my all-out effort, 'nothing's too good for my little Fi-fi' audio extravaganza attempt. In all the tubes except for one in the line stage, the two triodes in each tube are paralleled, resulting in one larger triode per tube. Each phono stage channel uses 4 of these composite triodes, and the line stages each use 1 of them plus the unparalleled tube. The phono stage has an input triode followed by a cascode of 2 more, and the cascode is buffered by a constant current-sunk cathode follower stage for good drive capability. A cascode is a stage in which two triodes (or other amplifying devices) are stacked one on top of the other, rather than in series as they would be in so-called cascade or series connection. Phono stage places the RIAA EQ network in the feedback loop. Since a lot of gain is needed at 20Hz relative to 1kHz, the cascode and the lone triode stage together provide the necessary open loop gain so that the pre does not run out of steam, gain-wise, at 20 Hz, where 10X more amplification is needed relative to 1kHz. So that's where 8 of the little tubes went, 4 per side. The line stage is just a two-stage one with one 6922 providing two stages of amplification, and this is buffered by another constant current sunk cathode follower. It uses negative feedback. B+ is a regulated 310Vdc, and heaters are provided by slowly rising DC at turn-on as well. B+ comes on after tubes have warmed up after turn-on. In general, it has been reliable since the tubes are gently handled by the circuits they're in. The preamp is still going strong after 21 years' use and is on its second set of tubes. I see no need to replace it. The preamp is a two box one with an umbilical cable using connectors of many pins to connect them together.

Thanks!

Your design is all very well thought out and I can understand it.

BTW: Professionally, I had a lot to do with high-tech in the context of fundamental physics research and had to design unique devices for this. My playing around with old-fashioned tubes is a private counterpoint to that. I could also make everything more technically complex, or more comfortable, but I'm fascinated by the simplicity of tube circuits right now and I'm trying to push that to the extreme.

 

[Philbo King]

I always thought it was pretty cool to see the 6L6GC tubes in my Fender Bassman light up blue-violet when I hit a chord...

 

[egellings]

No, of course not. But it's tough to get the same gritty sound with SS.

True.

 

[egellings]

Bass guitar amps historically were designed to be cleaner. Then came the dirty bass explosion

I like my bass the way I like my martinis, which is neat.

 

[egellings]

That, also did not endure the scrutiny of Science. There is, somewhere in ASR a thread where a person shows that ... same sound can be achieved with SS and some EQ....

High nd Audio has become a design aesthetics. The components have a look. These pleases the eyes, more than they actually please the ears. The differences between a decent tube and a deceent SS are not as marked as they want you to believe... In many instances they sound likely the same .. I haven't verified but, there is a thread here that has some sound clip from SS and from a SET amp .. It is not easy as one would think, to pick which is which
Pictures are better to describe my point...

Here is a superb ASR-reviewed amplifier, capable of driving most headphones on the planet:

around 4 wpc of pure low THD ... >100 SINAD, perhaps 110 dB

And the Woo Audio Luna.. Pure Class A Tube .. they don't mention its power, not much technical specifications but ..

Even for us ASR'ists. We have to admit this is beauty.. And it costs $8,999.99...

Peace.

Amplifier as art object.

 

[Curvature]

Bingo.



People don't need accurate equipment to enjoy music "to the greatest degree." Our brains are quite good at making due with what we've got. Music has been the subject of deep love, life-changing even, for countless people since the recording age, and very few music listeners have had "accurate" systems. It would be absurd to say passionate fans of The Beatles, Elvis, Ornette Coleman, Bach, or countless other musicians, were not "real music lovers" because they didn't have accurate systems.

That goes for any music lover, audiophile or otherwise.

I believe you are seeing things through your own bubble of interest, in this case.

You might not have noticed it, but you changed the subject. He was talking about a specific group of charlatans that love the experience of the equipment, using it, showing it off, tweaking it, etc., etc. They exist.

Remember this quote? "Audiophiles don't use their equipment to listen to your music. Audiophiles use your music to listen to their equipment."

What you said is true, and I agree with it, it's just irrelevant to the point @Jim Taylor was making.

 

[egellings]

No, of course not. But it's tough to get the same gritty sound with SS.

Gritty sound in guitar amps is generated when they are overdriven and clipping & other distortion generating mechanisms kick in. Tubes and SS devices will handle that differently, no question there, if for no other reason than that an output transformer is involved in tube, but not transistor designs, some McIntosh amps notwithstanding. When operated in their linear regions, it would be difficult to hear differences between competent tube & SS designs.

 

[fpitas]

Gritty sound in guitar amps is generated when they are overdriven and clipping & other distortion generating mechanisms kick in. Tubes and SS devices will handle that differently, no question there, if for no other reason than that an output transformer is involved in tube, but not transistor designs, some McIntosh amps notwithstanding. When operated in their linear regions, it would be difficult to hear differences between competent tube & SS designs.

Well, yes of course. I was talking about the 30% THD region, where the screen supply has sagged badly and you can see parasitic oscillation as the anode swings throiugh the tetrode kink. Hard to get that sound from a transistor.

 

[egellings]

Well, yes of course. I was talking about the 30% THD region, where the screen supply has sagged badly and you can see parasitic oscillation as the anode swings throiugh the tetrode kink. Hard to get that sound from a transistor.

I'd want to put a tube amp suffering that badly out of its misery. Poor thing!

 

[fpitas]

I'd want to put a tube amp suffering that badly out of its misery. Poor thing!

A friend tried "fixing" it with better parts in the supply. It sounded awful, nothing like it should. He put the cheap parts back in.