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 22 Sep 2019, 16:35

All times are UTC - 6 hours [ DST ]




Post new topic Reply to topic  [ 247 posts ]  Go to page Previous  1 ... 13, 14, 15, 16, 17, 18, 19 ... 25  Next
Author Message
 Post subject: Re: 6EM7 power amp
PostPosted: 27 Aug 2013, 14:56 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 5136
Location: Australia
The power tranni s rated 144mA but gets real hot. Total current is only 95mA so it should be in spec. No wonder the amp is dead quiet I just realised a used a 20H choke rated at 100mA. Two stage PS filter with 220uf of caps.

Sounds excellent and drives my low efficiency 2-ways to good levels. Not quiet the depth or clarity of Paris which was dual mono with integrated preamp but still very nice.

_________________
Projects:"retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp


Top
 Profile  
 
 Post subject: Re: 6EM7 power amp
PostPosted: 08 Sep 2013, 23:42 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 5136
Location: Australia
Here are some shots under the bonnet. Also I did some testing on the amp.

Max Power: 1.8W RMS -under what I expected expected into 8.2ohms
Frequency response: 15hZ to 39KhZ (-3db points)
Current through power section 44mA.
Gain: 9db.
Measured noise: 4.2mV RMS - sounds a lot quieter than this. In fact I can hear nothing through speakers of 86db efficiency?

While I had the amp on the hoist I added some 0.1uf polies snubbing the NP bypass caps on the cathode of the power section. I usually do this believing electros (even NP ones) don't pass high frequencies well. Thoughts are that the polies will do a better job. It's worked in the past. Did not do it initially on this amp thinking it wouldn't be a good performer. Boy was I ever wrong. Now hopefully airier highs. Yet to prove.
Attachment:
Underneath_I.jpg
Attachment:
Underneath_II.jpg


Here is some shots of under the bonnet. Graphs to come.


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.


_________________
Projects:"retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp


Top
 Profile  
 
 Post subject: Re: 6EM7 power amp
PostPosted: 09 Sep 2013, 07:56 
Offline

Joined: 05 Jun 2012, 13:10
Posts: 196
Location: Darboy, WI, USA
Your photography is on par with your amp building. Nice work all the way around.

_________________
Thanks,
Ross in Wisconsin


Top
 Profile  
 
 Post subject: Re: 6EM7 power amp
PostPosted: 09 Sep 2013, 17:53 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 5136
Location: Australia
RossD wrote:
Your photography is on par with your amp building. Nice work all the way around.

Thanks RossD.

_________________
Projects:"retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp


Top
 Profile  
 
 Post subject: Re: 6EM7 power amp
PostPosted: 09 Sep 2013, 17:58 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 5136
Location: Australia
Graph results from Arabella.
Attachment:
image.jpg
Attachment:
image.jpg
Attachment:
image.jpg
Attachment:
image.jpg
Attachment:
image.jpg

The green graph is the input in all graphs. The load was 8.2ohms in all graphs
The top graph is 1Khz SQR wave at 1.8W
The second: 1Khz SQR
The Third: 10KhZ SQR
The Forth: 100hZ SQR
The Fifth: 10Khz SQR at 1.8 W


This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.


_________________
Projects:"retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp


Top
 Profile  
 
 Post subject: Re: 6EM7 power amp
PostPosted: 11 Sep 2013, 21:22 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 5136
Location: Australia
Thoug Arabella tested all the way down to 15hz into a pure resistive load I wanted to listener to the low-end response in room. Using my 2-way speakers (VoxDeux) with thier 5" woofer\mid and Stereophile test CD I started at 100Hz and continued down the tones using only my ear as judge.

No drop in vol. at 63Hz but at 50 you could detect a small drop in volume. 40hz there was another drop in volume but still good energy and quite audible here. At 31Hz all the way down to 20 the cones were still vibrating strongly but nothing audible. The port at the back of the boxes was going off!

Arabella has problems going down to 50 and even 40Hz. My stereo subwoofers(VoxItBassO) come in at 50Hz down to 31 so plenty of reinforcement for the very low register. Nice to see what I saw on the test bench was echoed in real life.

_________________
Projects:"retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp


Top
 Profile  
 
 Post subject: Re: 6EM7 power amp
PostPosted: 11 Sep 2013, 23:08 
Offline
Project Author
User avatar

Joined: 06 Apr 2009, 10:08
Posts: 1591
Location: US Pacific Northwest
mwhouston wrote:
I started at 100Hz and continued down the tones using only my ear as judge.
I used to do this kind of test but no longer.

After a professional hearing test many years ago I decided I need to keep track of my hearing range. Fact is, today my hearing is very good from about 55Hz up to about 4500Hz and from 6000Hz up to about 11500Hz. But there is a distinct rolloff from 56Hz downward with about a 50 dB loss at 20Hz (but I can still hear that low :thumbsup: ), about a 10dB valley between 4500Hz and 6000Hz, and at the high end my ears roll off starting at 11500Hz and my hearing is completely gone by 15500Hz. Unfortunately my ears are not what they used to be.

Now I test amps with electrical test equipment and audio sound meters. I wish it wasn't so but there is really nothing I can do about it. I still love my amps and the way they sound (to me) but I can't really be sure of how they are doing by just ears alone. :(

_________________
Matt
It's all about the Glass!
http://www.CascadeTubes.com
Cascade Tubes Blog


Top
 Profile  
 
 Post subject: Re: 6EM7 power amp
PostPosted: 11 Sep 2013, 23:18 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 5136
Location: Australia
I have played music to audio conscience friends with good bass in the mix. I switch in and out the subwoofers. A few have remarked the subbies are almost a bit of a waist. The amp speaker combo seems to work well. It leaves me with a smile on my dial after and into many hours of play. Too me it is all about "sounding good and sounding right". If I think the system does that I'll keep building and listening.

_________________
Projects:"retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp


Top
 Profile  
 
 Post subject: Re: 6EM7 power amp
PostPosted: 13 Sep 2013, 22:47 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 5136
Location: Australia
Off topic but not sure where else to post this. The name under which I build is retro-thermionic. I like the name but don't have a logo or symbol. I wonder if there are any creative artists out there who have some ideas.

I'd like an electronics or amp type symbol but nothing too obvious like a tube symbol. Or maybe something made from a few related symbols. I also build under Mongrel Dog Audio. Generally SS gear under this name. Trying to stay away from the alpha or ohms symbols. I need something new!!

Any suggestions? Some images of hand drawn ideas would be nice.

_________________
Projects:"retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp


Top
 Profile  
 
 Post subject: Re: 6EM7 power amp
PostPosted: 13 Sep 2013, 23:20 
Offline
Project Author
User avatar

Joined: 06 Jun 2008, 18:23
Posts: 5136
Location: Australia
mwhouston wrote:
Thoug Arabella tested all the way down to 15hz into a pure resistive load I wanted to listener to the low-end response in room. Using my 2-way speakers (VoxDeux) with thier 5" woofer\mid and Stereophile test CD I started at 100Hz and continued down the tones using only my ear as judge.

No drop in vol. at 63Hz but at 50 you could detect a small drop in volume. 40hz there was another drop in volume but still good energy and quite audible here. At 31Hz all the way down to 20 the cones were still vibrating strongly but nothing audible. The port at the back of the boxes was going off!

Arabella has problems going down to 50 and even 40Hz. My stereo subwoofers(VoxItBassO) come in at 50Hz down to 31 so plenty of reinforcement for the very low register. Nice to see what I saw on the test bench was echoed in real life.

What I meant to say here is Arabella has "NO" problems going down to 50 and even 40 Hz. But you may think that if there is a small drop in volume at 50 Hz then it may have a problem going below 50Hz. I can only say that there is still good volume at these low frequencies so: "Houston, no problem".

_________________
Projects:"retro2308" - chip based headphone amp | ”Calibre 834” - tube phono MM preamp | ”najah” - Raw 180W Tripath Class D power amp | "Icon" - Shuguang CV-181Z preamp


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 247 posts ]  Go to page Previous  1 ... 13, 14, 15, 16, 17, 18, 19 ... 25  Next

All times are UTC - 6 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 14 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