AC or DC??? - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th August 2003, 07:21 AM   #21
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Default Selling DIY and kit amps

If you go by the name stuff only, then there's a good chance of a return on parts investment. However, I find most of the kit stuff to be horribly compromised compared to what you can make for yourself. My approach now is to buy lots of surplus/second hand power amd filament transformers, as these can easily be recycled into other amps, as well as the best quality signal iron I can afford, especially if it's flexible. I bought some Lundahl 1620 PP OPTs last year,and so far the've been in at least a dozen experiments, especially as they have 3 different winding configurations and impedances, so they've earnt their cost. If you don't fry it, iron is forever.

By hunting around, and buying well, I've now got enough signal and power iron to build about 2 dozen stereo power amps plus a few pre's. Same with tubes; I look to see what's interesting that other people have used and try the less common ones esp when I find them cheap. The best tubes aren't always expensive. For instance there are a few pentodes that'd make great drivers for your 2A3 and don't cost much (most 'philes are a'scared of pentodes). Some might need a second PS, but if you have some iron you've aquired cheap, why not?
  Reply With Quote
Old 27th August 2003, 09:53 AM   #22
SHiFTY is offline SHiFTY  New Zealand
diyAudio Member
 
SHiFTY's Avatar
 
Join Date: Jul 2002
Location: New Zealand
Why is 6SN7 so damn popular! I guess they can pass a lot of current, but they run hot, are inevitably microphonic and so on.

Also with just 1/2 a 6SN7 driving a 2A3 (or 6SN7 SRPP) gain will be well down, and power will be a couple of watts less than a 6SL7, which can drive it to the full 4.5 watts.

What about a 6SL7 front end, with a 6SN7 as driver? Hmmm, time to break out the breadboard...
  Reply With Quote
Old 27th August 2003, 10:07 AM   #23
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Quote:
Originally posted by ShiFtY
Why is 6SN7 so damn popular!
Because they generally sound good?
They're also very linear (low measured and low order distortion).

Quote:
I guess they can pass a lot of current, but they run hot, are inevitably microphonic and so on.
Not a lot of current by my standards, and none of the 6SN7's or 6J5's I have are particularly microphonic. I can think of a lot of other tubes that are worse. Microphony certainly isn't an inherent flaw with the 6SN7 family.

Quote:
Also with just 1/2 a 6SN7 driving a 2A3 (or 6SN7 SRPP) gain will be well down, and power will be a couple of watts less than a 6SL7, which can drive it to the full 4.5 watts.
Gain will be down, but there is enough headroom in the 6SN7 in most cases to run a lot of signal into it and drive the amp to clipping. If you had a CDP through most active line stages it would be plenty.

A 6SL7 - 6SN7 - 2A3 will have too much gain most of the time. Also consider a 6SN7 - 12B4 - 2A3. Both stages could be resistively loaded and still give enough gain, and the 12B4 will do a cracker job as driver.
  Reply With Quote
Old 27th August 2003, 04:16 PM   #24
diyAudio Member
 
Join Date: Sep 2002
Location: Oregon, USA
Well, as long as I don't have to cut into my chassis again, I'm game for anything. I've heard of trioded EL84s (did I get that right?) being used as driver tubes for 2A3/300Bs. So the 12B4... that's a single triode per envelope, right? That would require at least another socket (I could use one half of the 6SL7 for each channel), so that's not such a great option for me now.

Quote:
If you had a CDP through most active line stages it would be plenty.
But I don't. I could build a DAC that would produce enough output to work through my passive linestage, but re-doing my phono stage will be a little more complicated (kit built on a PCB).

Quote:
A 6SL7 - 6SN7 - 2A3 will have too much gain most of the time.
Which means I could run my autoformer turned way down, which would help, right? Or will the high gain cause other problems?
  Reply With Quote
Old 31st August 2003, 08:31 PM   #25
diyAudio Member
 
Join Date: Sep 2002
Location: Oregon, USA
Hi Brett,

More ideas. Bottlehead sells "hole shrinkers" which will allow a 9-pin socket to be put into an octal cutout, so that takes care of that problem.

So now for the ECC99... how does this look as a starting point?

http://www.pmillett.addr.com/images/ECC99_SRPP_2.PDF

It's an SRPP ECC99 headphone amp. About 20mA, 300V B+. Since I would buy 2 ECC99 tubes (so I don't have one empty socket), I'll have a spare pair of triodes, so I was wondering if this would be worth trying out before I go for the active load? Or are there any reasons why an ECC99 SRPP isn't a good idea?

Thanks,
Saurav
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 01:53 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2