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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 25 Nov 2015, 10:01 
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Steph wrote:
I am not locating the schematics for this, perhaps I missed it. Would anyone have a link for this?
Third entry, (http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=5222&start=2) along with the frequency response and power output numbers.

Here it is again:
Attachment:
Schematic - as built (small).jpg
Note that only one channel of the amp is shown. The other channel is identical. The power supply shown is for both channels. Also note that the coupling capacitor is 0.01µf. This is not labeled on the schematic.

You can also find the information on this amp at Cascade Tubes.

It's a very straight forward build. I listen to mine every day in my office. I love it. :up:


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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 25 Nov 2015, 11:18 
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Joined: 02 Mar 2009, 12:41
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mwhouston wrote:
Soundbrigade I registered with tubediy. Do you have a link to the Darling 6L6 schematic?


Here: http://www.diytube.com/clementine/clementinemanual.pdf

But check the various threads in there: http://www.diytube.com/phpBB2/viewforum.php?f=19

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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 25 Nov 2015, 23:10 
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Joined: 30 Oct 2015, 07:44
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Suncalc wrote:
Steph wrote:
I am not locating the schematics for this, perhaps I missed it. Would anyone have a link for this?
Third entry, (http://diyaudioprojects.com/Forum/viewtopic.php?f=9&t=5222&start=2) along with the frequency response and power output numbers.

Here it is again:
Attachment:
Schematic - as built (small).jpg
Note that only one channel of the amp is shown. The other channel is identical. The power supply shown is for both channels. Also note that the coupling capacitor is 0.01µf. This is not labeled on the schematic.

You can also find the information on this amp at Cascade Tubes.

It's a very straight forward build. I listen to mine every day in my office. I love it. :up:


Thanks very much. Evidently I wasn't reading thoroughly enough. It was my impression that this schematic was an earlier work in progress. I thank you for reposting it.


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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 31 Jul 2016, 10:22 
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Posts: 168
Hi Folks.

We have added this build to the project pages.

http://diyaudioprojects.com/Tubes/6CY7-SET-Amplifier/

Thanks for sharing your work Matt.

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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 31 Jul 2016, 13:50 
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Posts: 135
Hi, cool build.

I have a couple comments.

Since you felt like you had too much gain and therefore left the first stage unbypassed, maybe there is a solution for the limited bandwidth. I believe those transformers have a very limited primary inductance (3H). Given the fact that the power triode rp and primary inductance form a high pass filter you need an output transformer with a larger inductance (or a triode with lower rp). 3H and rp=1k puts you right around where you measured 50Hz. Another solution is since you have plenty of gain is to add some global feedback to increase bandwidth, the core shouldn't saturate since you are only asking 1.5watts. Theoretical max open loop gain is 12.5 or 21.8db, you could use 10db of feedback and still get a loop gain of 3, plenty for today's sources to attain 1.5 watts out. Try a CCS on the first triode's plate and suitable RC network at the cathode.

If your speakers are the limiting factor for bandwidth of course this is all pointless. For others that might be driving very efficient horns and want good bandwidth with cheap transformers this could be a solution.

Just my $.02


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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 31 Jul 2016, 18:56 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
Just read the new post on the site. I have emailed Gio about one small typo but post is good. It's about time it has nearly been year since anything new went up. But worth the wait.

Amp looks excellent and by all accounts sounds excellent too. Good work Matt and good post Gio.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 31 Jul 2016, 19:45 
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Location: NZ
Just catching up with this. Another excellent project Matt, thanks for sharing.

mwhouston wrote:
The 6N7 could make a good PP amp low power of course. Two pentodes in the one metal tube.

The 6N7 is a twin triode, not a pentode. I also use this as a driver for the 6CB5A.


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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 31 Jul 2016, 23:02 
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Yes you are right. Not sure where I got the pentode bit from. I think I saw a schematic which showed two 6N7s draw as pentodes. I must check in the meantime.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 01 Aug 2016, 12:28 
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Joined: 07 Dec 2015, 14:21
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6N7 is a twin triode with a shared cathode. I used it to drive my 6HJ5 amp. http://www.transcendar.com/customer-amplifiers/

I CCS load the plates and have an adjustable cathode resistance to adjust plate voltage, the cathode is suitably bypassed with a cap. Both triodes run in parallel.

Va=200
Ia=8mA

I have a bunch of 6AU6 tubes which are pentodes that I want to triode wire for drivers. They seem like good candidates but I don't have any 7-pin sockets.


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 Post subject: Re: 6CY7 Stereo Amp
PostPosted: 01 Aug 2016, 14:12 
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famousmockingbird wrote:
Since you felt like you had too much gain and therefore left the first stage unbypassed, maybe there is a solution for the limited bandwidth. I believe ...
I have two issues with this whole post I would like to address.

1. "limited bandwidth" - I don't believe that this amp has limited bandwidth. This amp has a 3dB bandwidth of ≈46Hz to ≈30kHz; this is hardly "limited". Many people mistakenly assume that if it doesn't go flat to 20 Hz then it is limited. After specifically studying the active frequency content of many types of music, the action of the cochlea and the human brain's response to sound, and the historical development of the audio amplifier and it's applications, I am confident that the blind quest for 20Hz is not only misguided, but has ruined many fine amplifier designs. For further reading, please consult "How Much Audio Bandwidth?".

2. "different triode", "negative feedback", "CCS Load" - These things are all well and good if one wants to use them. However, each and every one of those suggestions takes away a portion of the unique response of this amplifier. After over three decades of designing amplifiers for audio, instrumentation, RF, and servo loops I have come to some general realizations concerning the design of amplifiers. Most importantly, with respect to audio amplifiers, forced operation of a device using feedback (and this includes a CCS load, as this is just a self fed feedback correction) may produce what appears to be "very good" numerical performance of an amplifier, but seldom produces the most pleasant sounding piece of equipment. And yes, I do understand that unbypassed cathodes are a type of feedback. However, that particular topology does not, in general, introduce the same level of negative influences as the other typical feedback structures.

Please accept that I am not simply rejecting your input. These are all things I've considered for various amplifiers at various times. They just are not really applicable to my reasons for this design and build. This particular design has ruminated on these pages for several years. I simply decided, and circumstances conspired to make it so, that it was time for it to see the light of day.

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