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Old 1st March 2009, 05:50 PM   #11
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Default READ THIS

Marko,

Welcome to the wonderful (albeit confusing) world of tube audio.

I myself are a relative "newbie" to the this interesting hobby. To put into "laymans terms" a lot of what has been posted and to maybe clarify some things for you from the perspective of a "newbie" also.

1: Reason for treating your speakers as 4ohm load is that tube equipment is VERY impedance dependant and also quite fragile when the load encountered is low. By having the clear spec's of your speakers we can infer a 4 ohm nominal load for the Output transformer calculations.

2: The overall power output requirement is going to be dependant on listening position, room size, your personal taste etc. As a "frame of reference" from someone who has very recently "been there and done that", I am listening right now as I type Carlos Santana "Moonflower" played thru a set of Yamaha's A-636's (smiliar SPL to your speakers) I am about a meter away and pretty much "dead set on axis" with them.
My 6V6PP amp is only capable of about 8 watts/channel max (which I cannot see with my limited input signal voltage) so I fgure I am pushing only about 4 watts class A.

I do not have a dB meter but the level is more than adequate (for example I would not be able to hear someone talking at a normal conversation level even 6 ft away)

I can go to my work area 20 ft away and still have a nice listening level with this setup.

3: As noted a Class A Tube amp with 60W output would be a MONSTER. Even in Parallel Push pull class A would be pretty hard to reach and need some pretty pricey tubes.

But that being said, IMHO there is nothing that I can afford in SS that even approaches the sound of my humble little "junkbox" 6V6PP. If I were to build it from the ground up with commercially available higher quality components my cost (excluding hours of personal labor) would barely top $2200 US. That is putting serious money into the "iron" and capacitors.

On a budget it could easily be built for about $800US and be infinately better quality than what I personally have.

4 I am in no way stating you should run right out and start slapping together a 6V6 PP amp.

What I am stating is this.

If you are not afraid of voltages that can KILL! (No JOKE) and will seriously respect that.

If you have decent mathematics skills.

Learn Ohm's and Watt's laws backwards and forwards.

Can strip wire and solder reasonably well

Can read a schematic.

Then you can probably build yourself a nice amplifier. Considering the budget that you seem to be prepared to expend you will not regret the choice of tube amplification.

As a Newbie here are my recomendations if you are prepared to venture into the realm of DIY.

#1) "GOOGLE" is your friend! Start looking for published schematics. Download them and look them over. Try to understand a little of the overall topology and theories. It will not take long to see many "common threads" in the many many designs out there.

#2) Get yourself a copy of an RCA Tube manual. RC-30 is a good start. Read the sections on resistance coupled amplifiers and Tube applications. Perform some of the math excercises that are in there.

#3) A "preamp" might be a place to start but since you are not 100% sure of where your SS equipment is lacking you might consider a relatively easy and inexspensive "integrated" VT amp as a first project this way you can have a taste of the whole project with a reasonably guaranteed outcome.

"Mistakes" that I made that I might help you avoid.

Do not approach this as just a "Build A Kit" and I now know about tubes project. Learning the "basics" from the available info is well worth it. By now understanding the theory and characteristics of tubes from all the reading and practice I can look at a schematic and make calcs of Power Out and Distortion etc. This helps me to understand what that particular design will result in.

To get a sample of the "sound" you could look at an SE design (by default all SE has to be Class A) that makes somewhere in the 4 to 5 watt range with maybe 6BQ5 (EL84 "across the pond").

Or for a less expensive approach as far as OPT's a Push Pull circuit using similar tubes and gives a doubling of relative power along with less distortion.

I have found that I like the sound with Tube Rectification but that is just an opinion.

Also for ease of constrution on a first project Self Bias is a good idea.

Hope this helps in some small way!
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Old 1st March 2009, 10:28 PM   #12
Marko25 is offline Marko25  United Kingdom
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Great post Coldcathode, very reassuring that tubes may still be an option for me despite what people keep saying both on this thread and another I have in the SS section.
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Old 1st March 2009, 11:37 PM   #13
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Default Re: The daunting world of tubes (where to start)

Hi Marko,

Good advice preceeding this, so on this vast subject I would not like to repeat.

But folks, are we not missing something here??

Quote:
Originally posted by Marko25
....it was whilst playing a mobile fidelity recording that I noticed the ghosting on the opening track i.e. the track starts before it actually starts.
.................................................. ....

This brought me to the conclusion that my integrated amp was losing a lot of detail in the system and as my headphones plug into my amp....
No.

The well-known 'ghosting' on some vinyl records is part of the input signal, and I am not aware of any topology that is amplitude selective as in losing low amplitudes. In this sense one must look elsewhere for the noticed difference, not at the type of amplification.

I am at a loss to exactly explain your experience, unless you played the headphones at quite a volume, such that you noticed the very low ghost signal there and not on the loudspeakers. But you stated that you tried loudspeakers at all volumes .... It can also not be that the low signal would be lost in background noise on the loudspeakers; for that the noise would have been very noticable and you would not have put up with such a system. Strange ...

With this I am not shooting down any interest in tube technology - I come from the era, so to speak. But they will not be more transparent than good solid state equipment; in fact, academically it should be the other way round.
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Old 2nd March 2009, 12:56 AM   #14
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I am not sure exactly what he is hearing as I am not a big " Vinyl Guy" But I do know that for some reason I "hear" things now thru the tube amplifier (exact same source, same drivers, same room, same tracks) that were either previously inaudible or masked somehow with SS amplification. I have had all manner of receivers/power amp in SS over the years. Some cheap and dirty some higher end stuff. I honestly prefer the tube amp.

Now for my "Home Theater" in my family room where we watch movies and "impress" friends, I have Solid State. It is used rarely and makes a "lot of noise" Especially my handbuilt 12" subwoofer cabinet with 200W plate amp. For all the new digital surround sound effects etc SS is the way to go. But the last time I checked I have TWO ears. So most of the time 2 speakers is good enough for me.

Marko,

I still suggest a foray into "Hollow State" you will not be sorry. I find that there is nothing more satisfying than listening to one of your favorite tracks on something that you "built yourself".
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Old 2nd March 2009, 07:49 AM   #15
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Default Tube Info

Great earlier post 'cold cathode'.

Mark,
As you've probably noticed from the responses your getting, tubes will always be dear to those of us that grew up with them.
I bought 2 Velleman K8010 kits in 2001 at a great price of $800.ea
These are beautiful PP Quad Pentode KT88 Amps, although Velleman tends to use some cheaper components. I learned allot more about tube circuits in the process of 'Mods' on these and am pretty happy with them now (regardless of what Aqua Blue thinks).
They sure warm-up the 'feel' of my living room at night.

Me I'm still trying to figure the new world of solid state and digital, somewhat your situation in reverse. There is a lot of great information out here on tube amps. Suggest you casually read some of the better articles available verses trying to learn 'textbook' style.

One of my favorites, I've re-read many times: Articles by John Broskie at : John Broskie's Guide to Tube Circuit Analysis & Design
http://www.tubecad.com/
His initial writings beginning March 99 address the newer generation that has little knowledge of tube circuit design: He does an excellent job of it; tying modern solid state circuits to their actual tube predecessors and tube circuit equivalents.

We have to thank DIYAudio'er Nigel 'thevoice' for mirroring Steve Bench's great website at:
http://greygum.net/sbench/sbench101/

Of course any of the issues of 'Glass Audio' that can be obtained through AudioXpress.
Here's a build for you":
http://www.audioxpress.com/magsdirx/..._special05.pdf

AudioXpress's 'Audio Classroom Series'
http://www.audioxpress.com/resource/...lass/index.htm

Many more good references are out there, Sorry I know I left some out. We love our tubes!! Don't get me wrong; I'm in the process of a Pass F5 build right now, everything has its place.

Charles
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I'm kinda curious about that myself........
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Old 2nd March 2009, 08:40 AM   #16
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I challenge "Joppa's rule" for the very reasons given already - rooms have shrunk in Europe in particular. I live in a block of flats where all the original flats have been divided in two and sold off to residents - not unusual at all where people are after a foot on the housing ladder. I and several friends now drive panel speakers - Apogees, Magnalpanars - with DHT amps of 10 watts up to 15 watts. And such panels are insensitive. Also music listened to in our case is classical and jazz - essentially background listening - not techno music for dancing to. That'a a set of circumstances which makes a 15 watt amp just fine. I leave it to the OP to see if these circustances sound similar to his.

I think that if you are going to really benefit from this experience of building with valves, you need to think in terms of push pull DHTs, and that points straight at 300b outputs as the usual solution for 15 watts. They are the highest outputs for DHTs at sane voltages, and are a superb valve.

I and several others (though not the majority of valve users I must be careful to say) believe that to get the full finesse and detail out of the music directly heated triodes (DHTs) are the way to go. So if they're right for outputs they're right for input and driver tubes too. It's going to be much easier for you not to use DHTs for the input - choose a design with 6SN7 s for instance, or use a two stage amp with a high gain triode into a transformer phase splitter such as Lundahl LL1660/10mA. If you truly want a killer amp, use 01A into 46 into 300b. That means DC filament supplies for EACH 01A and 46 (and 300b if you want to go DC there). So add some transformers, Schottky bridges, big caps and voltage regs like LM10854/5/6 configured as current sources.

That's the theoretical side of it. In practice, the first thing I'd do is buy Morgan Jones "Valve Amplifiers" and read the relevent parts (most of the book!!) three times.

andy
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Old 2nd March 2009, 02:52 PM   #17
Marko25 is offline Marko25  United Kingdom
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Thanks Cowboy 99 for the links, you're quite right about the SS - Tube learning situation, I feel more confident in the SS side and the Tubes are a bit alien to me. The glow of the bulbs alone intrigues me enough to learn more.

Quote:
Of course any of the issues of 'Glass Audio' that can be obtained through AudioXpress.
Here's a build for you":
http://www.audioxpress.com/magsdirx/..._special05.pdf

AudioXpress's 'Audio Classroom Series'
http://www.audioxpress.com/resource/...lass/index.htm
I particularly like these links.

Unfortunately my integrated amp does not have the pre amp out section but instead I think I may try a Headphone amp to dip my foot in the water, I need one anyway. I'm considering doing 1 SS and one in Tubes, I personally think its a good place to start.

Now does anyone know where to find a good source for a design
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Old 2nd March 2009, 03:04 PM   #18
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Default Re: Tube Info

Quote:
Originally posted by cowboy99
We have to thank DIYAudio'er Nigel 'thevoice' for mirroring Steve Bench's great website at:
http://greygum.net/sbench/sbench101/
Excellent, I'd lost the link to the new hosting.

If he ever wants to not host it in the future, I will as there is too much good info there to be lost.
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Old 3rd March 2009, 04:53 AM   #19
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Default 'the tribes'

As long as the differing schools of thought remain towards tubes, tubes will never die out. The 'triodes' have their basis in quality, the 'pentodes' domain is power; the various configurations such as PP, Quad, Ultralinear, SE defined by such things Class A, AB, when A transitions to AB, AB to A............ What fun!
Andy defiantly has point about environment, my quad 60W pentode mono blocks have surely p___ some people off. Their driving 3.5 cu ft thiele-small tuned ports with old class EV T35 & 1823 mid horns (old school efficiency) which has made me seek secluded living quarters; kind of like have a problem-child that society has outcast. ..... defiantly have raised my rent! I'll leave with an email I sent to a friend a few years back...

...should of seen the grin on my face when this Buckethead Audioslave cover just vaporized one of my Sovitek KT88 ballast tubes: Voltage, smoke and glass .... Damn near killed my cat, best laugh in years !!; the window screen didn't even slow her down. Time to align the bias on these 'stacks'. She won't warm herself there anymore.... Cowboy
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I'm kinda curious about that myself........
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Old 3rd March 2009, 07:28 PM   #20
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Cowboy99,

Good post. Maybe tubes will 'die out' or begin to 'mutate' when old stocks fade out and new such becomes unreliable. But as I understand it is mainly the disco/guitar scene that keeps them alive!

(Just a detail correction: The Quad output is UL, not pentode, which is closer to triode than pentode, thus its advantages.)
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