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

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 Post subject: Re: Baxandall circuit
PostPosted: 05 Aug 2015, 16:38 
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Joined: 19 May 2011, 05:38
Posts: 36
remove the 33uf bypass capacitor on the second stage. this will lower the gain quite a bit.


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 Post subject: Re: Baxandall circuit
PostPosted: 06 Aug 2015, 00:27 
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Joined: 01 Feb 2015, 13:41
Posts: 144
Location: Athens-Greece
Thanks I am going to try it. I had it in mind but my concern is whether this circuit is designed to produce so much gain in general or I have done something wrong. I have seen another post by Matt without tone control where the connection between the two stages is different. Now, since I have the DPDT and put it in by pass mode, I have different arrangement that has to do with the remaining circuit of course. The basic question is the gain produced with the by pass line and the original one without tone control is more or less the same or is totally different? For the shake of completion I have already installed the optional pad proposed by Matt in order to reduce gain to -21 dB. I will re-post the alternative Matt's idea posted earlier in this topic.

I am very happy that there are many people here to exchange ideas and get assistance. IT is a pity that I do not have good knowledge in order to contribute more from my side. Thanks all of you out there

Dimitris


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 Post subject: Re: Baxandall circuit
PostPosted: 06 Aug 2015, 00:31 
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Joined: 01 Feb 2015, 13:41
Posts: 144
Location: Athens-Greece
The circuit without tone control. I notice the signal capacitor which is 0.1 uf insteaf of 1.0 uf used when tone control exists


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 Post subject: Re: Baxandall circuit
PostPosted: 22 Apr 2018, 03:38 
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Joined: 13 May 2016, 02:02
Posts: 129
Location: Javea, Spain
Suncalc wrote:
mwhouston wrote:
I could be cheeky and say what about a balance control?
I always considered balance controls cheating. I much prefer independent volume controls for each channel; much more flexible.

My build of this preamp will have six controls. Independent volume, bass, and treble controls for each channel. :beerchug:

Hi Matt, mwhouston,
Did either of you build this preamp with six controls? I'm really interested in this tone stack but would like to know whether either of you use it on a regular basis?


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 Post subject: Re: Baxandall circuit
PostPosted: 22 Apr 2018, 04:44 
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Joined: 06 Jun 2008, 18:23
Posts: 5112
Location: Australia
I have never built one.

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


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 Post subject: Re: Baxandall circuit
PostPosted: 07 May 2018, 09:50 
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Joined: 13 May 2016, 02:02
Posts: 129
Location: Javea, Spain
Question? Normally, when I'm looking at a valve circuit there is a capacitor (0.047uF or 0.47uF for example) in the signal line, between the anode of the first stage to the grid of the second stage The voltage rating for this capacitor has to be above B+. In the buffer stage of this preamp, the capacitor is between the cathode and grid. Does this mean I can use a lower voltage capacitor? If so how would I calculate a safe voltage.


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 Post subject: Re: Baxandall circuit
PostPosted: 07 May 2018, 10:55 
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Joined: 13 May 2016, 02:02
Posts: 129
Location: Javea, Spain
Oh I think I see now. Still high DC voltage but no gain. Comments please, I'm still learning and need guidance.


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 Post subject: Re: Baxandall circuit
PostPosted: 26 May 2018, 12:19 
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Joined: 13 May 2016, 02:02
Posts: 129
Location: Javea, Spain
I've just finished this 4S Universal Preamp with Tone Stack and I've popped it in front of my 6EM7. My hearing is pretty much messed up with too many loud concerts years ago plus my age now, so I have some problems with some frequencies. Being able to finely adjust each channel is a big plus. I like the 6EM7 on it's own, but I like it more now. I went for independent bass, treble and volume for each channel. Apart from the greater flexibility when listening, I am sure it was easier to wire than dual gang pots. At the moment I've got a Psvane "T" series MKII 12AT7 in and it sounds great. I'll be trying other tubes later.
Attachment:
Baxandall Tone Stack.jpg
Attachment:
Baxandall Guts.jpg


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 Post subject: Re: Baxandall circuit
PostPosted: 26 May 2018, 18:26 
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Joined: 06 Jun 2008, 18:23
Posts: 5112
Location: Australia
Glad to see you have fully embrassed the wine box amp movement. That's now two of us. You can feel the impetus building. Lol.

I'll assume your 6EM7 is another of Suncalc's designs. I built a few of these and really thought it was an excellent sounding amp. I even built a monoblock version. Over the last year or so I have use the Psvane 12AT7 "T" series MKIIs myself in my wine box 6L6 SE UL amp and think it is the best sounding driver tube for the amp.

When your knobs are on post some more images.

http://retro-thermionic.blogspot.com.au/2012/02/paris-duo-6em7-monoblock-power.html

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


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 Post subject: Re: Baxandall circuit
PostPosted: 27 May 2018, 03:27 
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Joined: 13 May 2016, 02:02
Posts: 129
Location: Javea, Spain
I have some black guitar knobs on order, they should be here in a week or so. Yep, it is one of Suncalcs' 6EM7s', a beautiful sounding amp.


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