Shake your Booty!

If they glow, this is the place to be
Post Reply
User avatar
rowuk
Old Hand
Posts: 453
Joined: Sun Jun 01, 2014 2:50 pm
Location: Germany

#1 Shake your Booty!

Post by rowuk »

I think that many of us use SS amplification for subwoofers - most likely due to convenience more than in an interest in sound quality. The best location for subwoofers is seldom in the same cabinet as the main speakers.

Recently we have had several projects with high power tubes - but more or less full range. What about getting reference ultra low frequency bass with valves. What do we need to do to drive 2-3 18" per channel or multiple 15", 12", 10" or any other MASSIVE low frequency array. Surely there are choices of OPTs, maybe considerations for bridged class A operation.

For the sake of argument, lets assume that our current speakers do a good job down to 40Hz-50Hz. Think about a speaker array for <20Hz to 50Hz, the efficiency of that array and the amount of power that we need below 50 Hz.

What do we need for a power supply? what happens to the bias? What kind of OPTs are even available for full power in very the lowest octaves? How do we maintain control of the multiple voice coils when we have large arrays? Can we get more optimum inductance for the LF by hooking the speakers up to the wrong secondary tap on a very large OPT?

Should we not even consider a real subwoofer amplifier with valves?

I hav a personal interest in doing something like this - maybe an 813 subwoofer amp? The more the power, the more flexibility in what speaker drivers will do the job. If we need EQ, then even more power is necessary.
Whenever I feel blue, I start breathing again.
User avatar
Nick
Site Admin
Posts: 15707
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#2

Post by Nick »

I would suggest starting with a valve with a low ra, so you can use a transformer with a low turns ratio, 6c33c or 6080 come to mind.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#3

Post by pre65 »

Nick wrote:I would suggest starting with a valve with a low ra, so you can use a transformer with a low turns ratio, 6c33c or 6080 come to mind.
Andrew I took a 6C33c amp to Witham fest yonks ago and it was said " it would make a good amp for bass". :)

Not "the bass" as in Dave, but bass speakers. :wink:
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
jack
Thermionic Monk Status
Posts: 5493
Joined: Wed Dec 29, 2010 8:58 pm
Location: ɐılɐɹʇsnɐ oʇ ƃuıʌoɯ ƃuıɹǝpısuoɔ
Contact:

#4

Post by jack »

The 6C33C-B is just one of the loveliest tubes - I have a bunch and they're on the list of "Must Make An Amp Soon" (have been for about 4 years :( ).

Just noticed - they're now about 20 quid each (including postage).

Eeek! (still excellent value, IMHO).
Attachments
mig25.jpg
6C33C_military_1.jpg
6C33C_military_3.jpg
Vivitur ingenio, caetera mortis erunt
User avatar
thomas
Old Hand
Posts: 910
Joined: Sat Sep 26, 2009 1:52 am
Location: N.W.Kent

#5

Post by thomas »

.... those photos did it for me :D ....I've gone and ordered some....
Yet another project for the list... :lol:
User avatar
jack
Thermionic Monk Status
Posts: 5493
Joined: Wed Dec 29, 2010 8:58 pm
Location: ɐılɐɹʇsnɐ oʇ ƃuıʌoɯ ƃuıɹǝpısuoɔ
Contact:

#6

Post by jack »

thomas wrote:.... those photos did it for me :D ....I've gone and ordered some....
Yet another project for the list... :lol:
Perhaps the amp could be called "Mach 3.2"? Certainly got to be one of the fastest terrestrially-bound valves there's been...
Vivitur ingenio, caetera mortis erunt
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#7

Post by pre65 »

Valves in planes is not that rare. :wink:

My PT15 were in Wellington radio sets. :)
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
jack
Thermionic Monk Status
Posts: 5493
Joined: Wed Dec 29, 2010 8:58 pm
Location: ɐılɐɹʇsnɐ oʇ ƃuıʌoɯ ƃuıɹǝpısuoɔ
Contact:

#8

Post by jack »

pre65 wrote:Valves in planes is not that rare. :wink:

My PT15 were in Wellington radio sets. :)
Ever seen a Wellington (bomber) doing Mach 3.2 then ?
Vivitur ingenio, caetera mortis erunt
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#9

Post by pre65 »

nickds1 wrote:
pre65 wrote:Valves in planes is not that rare. :wink:

My PT15 were in Wellington radio sets. :)
Ever seen a Wellington (bomber) doing Mach 3.2 then ?
Not yet. 8)
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
rowuk
Old Hand
Posts: 453
Joined: Sun Jun 01, 2014 2:50 pm
Location: Germany

#10 Pictures out of context can be deceiving.....

Post by rowuk »

I think that we are looking at a missile, not a jet airplane............. The valve is probably better put to use in a subwoofer than a missile.......
Last edited by rowuk on Fri Jul 11, 2014 4:23 pm, edited 1 time in total.
Whenever I feel blue, I start breathing again.
Romy The Cat
User
Posts: 86
Joined: Tue Jan 28, 2014 10:23 pm
Location: Boston, MA
Contact:

#11 Re: Shake your Booty!

Post by Romy The Cat »

If you looking for 20Hz to 50Hz, array then the question would be: what upper bass you have, or what would be next channel after your bass array. Your main objective shall be that your 20Hz to 50Hz shall have the same character of sound as your upper bass. Think in term of piano. Let pretend that your lower register would be 7' Bluthner circa 2004 but your upper register is like 5' feet Yamaha from 60'. You get the picture.... Also, you need to think about power. 50Hz and 20Hz are VERY different power demanding entities. Your room might be let say 20 sq meters and 6C33C would do it but at 20Hz your room would be 70 sq meters and you would need 200W. Do not forget that 3C33C is IDHT and it will not wok in A2 and you will not be able to push it further. To have high power SET for bass is an attractive opportunity, I wish I have one without wasting too much time, money and efforts on it. The best compromise I feel would be to have a hybrid amp with SS high current output stage driven by a single no-feedback tube stage with let say 30-35 time gain and at least 3-4V on grid.
Post Reply