The sound of... tubes !

Cobra2 · 29th January 2007, 07:46 PM

I have a dream...I want to build a really good tube-power-amp, that can handle a "normal" load (89dB / 8 ohm speakers), and fill a large room with sound of "modern" music.

I have a lot of prejudgment for tube amplifiers, have had a few small cheap ones...and heard a lot of really expensive sh**.

And have made some conclusions...(not necessarily correct, please educate me...)

I think I need a push-pull amplifier, I think I need 40(minimum)-80+watt output power. I have a 200W mosfetamp, and I sometimes use it ;-)

I like KT88 tubes & El34, 6SN7, 6SL7 & 12AX7 (as I have a few of them).
But I have no experience in setting up such a beast.
And no "iron" knowledge.

BTW, I hate hum, so I guess DC heaters are better?

Is there a schematic that I can use for a start?

Arne K

tkifowit · 29th January 2007, 08:07 PM

I had a Dynaco ST70 for my "rock" music and it was much better than the SET's I have now. It will give you tube sound with headroom for loud music.
There are lots of places to find schematic on line and even a couple of places that sell it as a kit!

Off subject I grew up in Chicago and I was an extra in the Blues Brothers movie. Great tag line.

EC8010 · 29th January 2007, 08:09 PM

You don't need DC heaters, just well-dressed heater wiring. Only RIAA stages need DC heaters.

Cobra2 · 29th January 2007, 08:35 PM

I should probably have written: NOT the sound of tubes...
as I want/need a "camelon", a transparent, and not "typical" tube-sound amplifier. I cannot play Sophie Zelmani or Eva Cassidy every day ;-)
My music collection also contains AC/DC...

I have soon spent a week surfing, & printing...and reading the book from Morgan Jones...
So many choices...

I would like to do a decent amp the first time, not time to experiment. Or I would have bought a Rogue...or...

Ok, ac heating is good enough, one choice less. 999 to go...

Arne K

BTW, I have been looking for a Dynaco Something 70...but they are extremely rare here...and expensive (the ones I have seen) in U.S.

AuroraB · 29th January 2007, 08:40 PM

Hi there...

I have doing quite a lot of reading on this subject lately, as I have also been looking into the subject of fullrangers too.

The conclusion seems to be that the old Dynaco stuff is not worthwhile, if you can't get them cheaply. The current Ebay trend seems to end at ++400$ for a used ST70, and even more for the higher powered amps. The irons in particular is not worth the money, as 2500-3000 NOK will buy you much better irons for a EL34 / KT88 / 6550 PP type amp.

adason · 29th January 2007, 08:44 PM

Hi Arne,

I might have a solution for you. Built a moscode! You can have it all. Transparent sound, tube like, yet drives even hardest loads easily.

ed

/ps, I have not built any myself, but certainly plan to/

Cobra2 · 29th January 2007, 09:01 PM

Thanks, but I want an all-tube amp. I have a couple of good mosfet-amps, and a AIKIDO pre...

I have been looking / searching for old usable amps to modify/upgrade, but found nothing worth buying.
And there are few kits in the high-power-range, without an even heftier pricetag...

For an amp to modify/rebuild: The far-east seems most interesting, as I have mentioned somewhere; at least you can get a shiny chassi for less than $ 200, and a handfull of parts...of very variable quality...
At least it is a start, when you find that your large parts-bin only have sub-200Volt parts...

Arne K

BTW...is "GLASSWARE TUBE MANUAL" useful?

Salas · 29th January 2007, 09:10 PM

Buy a MAC MC275 if you can. Or get an Amplimo OPT with cathode feedback windings and use a quartet of KT88s in UL. Driving stages schemes are plenty. Such an amp will drive speakers you mention vigorously and cleanly. Use about 20dB of feedback.

AuroraB · 29th January 2007, 09:27 PM

The Amplimo OPTs are all toroidals, right??
The prices are not bad at all, but toroids are still disputed in among the "Bottleheads" ??

I've been using SS amps for a lifetime, but I too have been eyeing at valves for quite a number of years. I also have a lot of experience with kW+ valve based transmitters, so I'm not afraid of the HVs either

Klimon · 29th January 2007, 09:35 PM

Most of the PP solutions will be one or the other variation on the classical williamson circuit (e.g. the famous dynaco although there are better alternatives); take your pick from one of the many circuits online (be it kt66 / kt88 / el34...). Transformer phase splitter could be interesting if you can afford it and dig something original (andrea ciuffoli has an x-former phasesplitter circuit for kt88 triode-wired but it probably doesn't take a genius to design a good amp with that topology; where simpler is better)... Although I haven't heard the tube yet kt88 has the reputation of sounding the most non-tubish (high and low-end extension and balls, not so much emphasis on midrange). Or mount a few tubes on your multiwatt SS for decoration

Simon

29th January 2007, 07:46 PM	#1
Cobra2 DIY ! diyAudio Member Join Date: Apr 2002 Location: Stavanger, Norway	The sound of... tubes ! I have a dream...I want to build a really good tube-power-amp, that can handle a "normal" load (89dB / 8 ohm speakers), and fill a large room with sound of "modern" music. I have a lot of prejudgment for tube amplifiers, have had a few small cheap ones...and heard a lot of really expensive sh**. And have made some conclusions...(not necessarily correct, please educate me...) I think I need a push-pull amplifier, I think I need 40(minimum)-80+watt output power. I have a 200W mosfetamp, and I sometimes use it ;-) I like KT88 tubes & El34, 6SN7, 6SL7 & 12AX7 (as I have a few of them). But I have no experience in setting up such a beast. And no "iron" knowledge. BTW, I hate hum, so I guess DC heaters are better? Is there a schematic that I can use for a start? Arne K __________________ Ars longa, vita brevis

29th January 2007, 08:09 PM	#3
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	You don't need DC heaters, just well-dressed heater wiring. Only RIAA stages need DC heaters. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

29th January 2007, 08:35 PM	#4
Cobra2 DIY ! diyAudio Member Join Date: Apr 2002 Location: Stavanger, Norway	I should probably have written: NOT the sound of tubes... as I want/need a "camelon", a transparent, and not "typical" tube-sound amplifier. I cannot play Sophie Zelmani or Eva Cassidy every day ;-) My music collection also contains AC/DC... I have soon spent a week surfing, & printing...and reading the book from Morgan Jones... So many choices... I would like to do a decent amp the first time, not time to experiment. Or I would have bought a Rogue...or... Ok, ac heating is good enough, one choice less. 999 to go... Arne K BTW, I have been looking for a Dynaco Something 70...but they are extremely rare here...and expensive (the ones I have seen) in U.S. __________________ Ars longa, vita brevis

29th January 2007, 09:01 PM	#7
Cobra2 DIY ! diyAudio Member Join Date: Apr 2002 Location: Stavanger, Norway	Thanks, but I want an all-tube amp. I have a couple of good mosfet-amps, and a AIKIDO pre... I have been looking / searching for old usable amps to modify/upgrade, but found nothing worth buying. And there are few kits in the high-power-range, without an even heftier pricetag... For an amp to modify/rebuild: The far-east seems most interesting, as I have mentioned somewhere; at least you can get a shiny chassi for less than $ 200, and a handfull of parts...of very variable quality... At least it is a start, when you find that your large parts-bin only have sub-200Volt parts... Arne K BTW...is "GLASSWARE TUBE MANUAL" useful? __________________ Ars longa, vita brevis

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

29th January 2007, 08:07 PM	#2
tkifowit diyAudio Member Join Date: Jun 2004 Location: Atlanta, GA	I had a Dynaco ST70 for my "rock" music and it was much better than the SET's I have now. It will give you tube sound with headroom for loud music. There are lots of places to find schematic on line and even a couple of places that sell it as a kit! Off subject I grew up in Chicago and I was an extra in the Blues Brothers movie. Great tag line.

29th January 2007, 08:40 PM	#5
AuroraB diyAudio Member Join Date: May 2001 Location: Norway, -north of the moral circle..	Hi there... I have doing quite a lot of reading on this subject lately, as I have also been looking into the subject of fullrangers too. The conclusion seems to be that the old Dynaco stuff is not worthwhile, if you can't get them cheaply. The current Ebay trend seems to end at ++400$ for a used ST70, and even more for the higher powered amps. The irons in particular is not worth the money, as 2500-3000 NOK will buy you much better irons for a EL34 / KT88 / 6550 PP type amp.

29th January 2007, 08:44 PM	#6
adason diyAudio Member Join Date: Nov 2004 Location: home sweet home	Hi Arne, I might have a solution for you. Built a moscode! You can have it all. Transparent sound, tube like, yet drives even hardest loads easily. ed /ps, I have not built any myself, but certainly plan to/

29th January 2007, 09:10 PM	#8
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Buy a MAC MC275 if you can. Or get an Amplimo OPT with cathode feedback windings and use a quartet of KT88s in UL. Driving stages schemes are plenty. Such an amp will drive speakers you mention vigorously and cleanly. Use about 20dB of feedback.

29th January 2007, 09:27 PM	#9
AuroraB diyAudio Member Join Date: May 2001 Location: Norway, -north of the moral circle..	The Amplimo OPTs are all toroidals, right?? The prices are not bad at all, but toroids are still disputed in among the "Bottleheads" ?? I've been using SS amps for a lifetime, but I too have been eyeing at valves for quite a number of years. I also have a lot of experience with kW+ valve based transmitters, so I'm not afraid of the HVs either

29th January 2007, 09:35 PM	#10
Klimon diyAudio Member Join Date: Apr 2005 Location: Leuven	Most of the PP solutions will be one or the other variation on the classical williamson circuit (e.g. the famous dynaco although there are better alternatives); take your pick from one of the many circuits online (be it kt66 / kt88 / el34...). Transformer phase splitter could be interesting if you can afford it and dig something original (andrea ciuffoli has an x-former phasesplitter circuit for kt88 triode-wired but it probably doesn't take a genius to design a good amp with that topology; where simpler is better)... Although I haven't heard the tube yet kt88 has the reputation of sounding the most non-tubish (high and low-end extension and balls, not so much emphasis on midrange). Or mount a few tubes on your multiwatt SS for decoration Simon

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
FS: Tubes, opamps and a sound card	sachi	Swap Meet	10	10th September 2009 11:22 PM
tubes sound	A'af	Tubes / Valves	127	28th April 2006 12:38 PM
Tubes lifetime and sound	Searcher	Tubes / Valves	19	21st February 2005 01:37 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read