DIY Audio Projects Forum
 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

It is currently 10 Dec 2018, 09:21

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 85 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8, 9  Next
Author Message
PostPosted: 19 May 2010, 12:51 
Offline
Editor
User avatar

Joined: 28 May 2008, 21:53
Posts: 4575
Location: Winnipeg, CANADA
sampleaccurate wrote:
Now I've got 6-8 weeks of waiting. :shock:

6-8 weeks of sipping wine and listening to good tunes seems like it would be more fun than waiting! ;)

_________________
[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


Top
 Profile  
 
PostPosted: 19 May 2010, 13:17 
Offline
Banned

Joined: 15 Mar 2010, 08:32
Posts: 487
Location: Canada
azazello wrote:
People talk that with AC heating muzically is better with more dynamic/!! :headphones:

Hi.

Yea, many say so. I believe it is due to music signal got modulated by the 120Hz hum harmonic coming from the filaments/heaters. So subjectively it may sound "better with more dynamic".
to some ears.

But I don't buy this. With pure DC heating (by battery), the music sounds so much clearer, & more transparent with much darker background. So 120Hz hum (AC heating), RFI plus sand coloration etc (SMPS & SS rectification), generated from the heating PS become history.

You find this effect pretty detectable for phonostages.

c-J

_________________
"If the facts don't fit the theory, change the facts" quoted Albert Einstein.


Top
 Profile  
 
PostPosted: 19 May 2010, 13:47 
Offline
User avatar

Joined: 05 Jan 2010, 21:16
Posts: 680
Location: Las Vegas Nevada USA
Gio wrote:
6-8 weeks of sipping wine and listening to good tunes seems like it would be more fun than waiting! ;)

I like your way of looking at it. :up:

_________________
Stephen


Top
 Profile  
 
PostPosted: 19 May 2010, 17:48 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4984
Location: Australia
azazello wrote:
People talk that with AC heating muzically is better with more dynamic/!! :headphones:

All my power amps and tube preamps use AC heaters. I have read where running heaters on DC polarizes them I'm not sure what affect that has on the sound though. Also some can switch the direction of DC through heaters to stop the polarizing.

Just stay with AC heaters. So easy.

_________________
Projects: "Grace" - Psvane 6SN7-SE Globe preamp | | "VoXUno" - Single driver MarkAudio 12P speaker | | "Lagoon Take 2" - Single stage tube preamp | Website: retro-thermionic


Top
 Profile  
 
PostPosted: 19 May 2010, 18:59 
Offline
User avatar

Joined: 05 Jan 2010, 21:16
Posts: 680
Location: Las Vegas Nevada USA
mwhouston wrote:
azazello wrote:
People talk that with AC heating muzically is better with more dynamic/!! :headphones:

All my power amps and tube preamps use AC heaters. I have read where running heaters on DC polarizes them I'm not sure what affect that has on the sound though. Also some can switch the direction of DC through heaters to stop the polarizing.

Just stay with AC heaters. So easy.

Have you built an amp using a tube having a directly heated cathode using AC heaters (300B for example)? From what I've read the hum is difficult to eliminate. But then I've never personally tried. DC is just as easy with a SMPS - actually easier since there are no "hum elimination balancing" pots to fool with.

I just fixed a bias problem on my driver stage in my new 300B amp and am happy to report the output power has increased by at least 6 to 10 dB. It's now at a good listening volume with no perceptible distortion. I can tell now the KT88 oddwatt is going to kick butt in the power department. From the scope it looks like I'm getting 7-10 watts a channel average power before I hear any audible distortion. The sound to me is crystal clear, and when it does distort it does so VERY gradually. If you can tolerate a little bit of low order even harmonic distortion you can probably get 15 or more watts RMS a channel.

I also discovered I can omit one of the 6SN7 sections and still drive the amp to full power with my CD player or computer audio interface (the 24 bit recordings of classical strings sound soooooo silky smooth).

Needless to say I'm a happy camper. :headphones:

_________________
Stephen


Top
 Profile  
 
PostPosted: 19 May 2010, 19:53 
Offline
User avatar

Joined: 05 Jan 2010, 21:16
Posts: 680
Location: Las Vegas Nevada USA
Noise readings from my scope indicate broadband noise about 50dB down from the peak output at the speaker terminals, however, most of this is radio frequency junk. It's NOT the SMPS or anything internal to the amp. It's there with the amp off or powering down while operating on capacitance alone.

The audio dynamic range or signal noise ratio is excellent. However, with ear on speaker there is an audible hum, but barely. I attribute this to poor PS filtering. I wanted to first see what I could "get away with" before adding more capacitors. I'll take care of that after I raise B+.

I also have not yet installed line filtering and high frequncy chokes I intend to put on the inputs and speaker outputs. Not enough to do anything to audio, but effective at blocking TV, FM, Wi-Fi and cell phones.

Now that the amp is working properly I can clean it up, install the B+ delay relay, put the filtering in, raise the B+ voltage and add PS caps.

I'll do a frequency response plot tonight and post it.

_________________
Stephen


Top
 Profile  
 
PostPosted: 19 May 2010, 21:49 
Offline
User avatar

Joined: 05 Jan 2010, 21:16
Posts: 680
Location: Las Vegas Nevada USA
Frequency sweep with 4 ohm resistive load at low power.

Image

Note the dips at 60 and 180 Hz. Power supply noise phase cancelling the sine wave frequency sweep. If I do it again they have better chance of showing up as peaks. If the gain is set higher they go away, but the response curve remains the same.

The response is only down 0.8 dB at 20 kHz, and is rock solid flat down to 20 Hz.

_________________
Stephen


Top
 Profile  
 
PostPosted: 20 May 2010, 03:49 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4984
Location: Australia
sampleaccurate wrote:
I just fixed a bias problem on my driver stage in my new 300B amp and am happy to report the output power has increased by at least 6 to 10 dB. It's now at a good listening volume with no perceptible distortion. I can tell now the KT88 oddwatt is going to kick butt in the power department. From the scope it looks like I'm getting 7-10 watts a channel average power before I hear any audible distortion. The sound to me is crystal clear, and when it does distort it does so VERY gradually. If you can tolerate a little bit of low order even harmonic distortion you can probably get 15 or more watts RMS a channel.

I also discovered I can omit one of the 6SN7 sections and still drive the amp to full power with my CD player or computer audio interface (the 24 bit recordings of classical strings sound soooooo silky smooth).

Needless to say I'm a happy camper. :headphones:

I download 24bit 96K flacs and burn to DVD-A. It sounds so dynamic.

_________________
Projects: "Grace" - Psvane 6SN7-SE Globe preamp | | "VoXUno" - Single driver MarkAudio 12P speaker | | "Lagoon Take 2" - Single stage tube preamp | Website: retro-thermionic


Top
 Profile  
 
PostPosted: 21 May 2010, 00:01 
Offline

Joined: 26 May 2009, 18:51
Posts: 130
Location: Lilburn, Georgia USA
Well, the idea of a pair of 300B monobloc amps is just too hard to resist so today May 20 I got online and ordered the Edcor iron (8 weeks to wait and drink beer not wine) also all the caps and a pair of JJ 300B for $110 a tube. Had to order the choke from AES as I will use two of my many spare 5U4 tubes. Where do you get 3 watt and 20 watt resistors? I think I will use some of the Odd Watt floating power and signal ground technology in this build just like in my built from scratch Odd Block KT88 amps. I will surely use SMPS filtered and regulated 5 volt DC to run my 300B heaters again floating and not grounded at all. 8 weeks. That will take a good bit of beer!
Regards,
Robert in Lilburn, Georgia USA


Top
 Profile  
 
PostPosted: 21 May 2010, 09:20 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 4984
Location: Australia
Robert, order matched tubes,

_________________
Projects: "Grace" - Psvane 6SN7-SE Globe preamp | | "VoXUno" - Single driver MarkAudio 12P speaker | | "Lagoon Take 2" - Single stage tube preamp | Website: retro-thermionic


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 85 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8, 9  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 27 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
DIY Tube Projects :: DIY Tube Amp Kits :: DIY Speaker Projects :: DIY Solid State Projects :: DIY IC / Op-amp Projects :: DIY Phono Projects :: DIY Cable Projects :: Hi-Fi Audio Schematics
© diyAudioProjects.com - Terms of Service - Privacy Policy