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Baxandall circuit
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Author:  mike567 [ 05 Aug 2015, 16:38 ]
Post subject:  Re: Baxandall circuit

remove the 33uf bypass capacitor on the second stage. this will lower the gain quite a bit.

Author:  dimitris1811 [ 06 Aug 2015, 00:27 ]
Post subject:  Re: Baxandall circuit

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


Author:  dimitris1811 [ 06 Aug 2015, 00:31 ]
Post subject:  Re: Baxandall circuit

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

Author:  john55 [ 22 Apr 2018, 03:38 ]
Post subject:  Re: Baxandall circuit

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?

Author:  mwhouston [ 22 Apr 2018, 04:44 ]
Post subject:  Re: Baxandall circuit

I have never built one.

Author:  john55 [ 07 May 2018, 09:50 ]
Post subject:  Re: Baxandall circuit

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.

Author:  john55 [ 07 May 2018, 10:55 ]
Post subject:  Re: Baxandall circuit

Oh I think I see now. Still high DC voltage but no gain. Comments please, I'm still learning and need guidance.

Author:  john55 [ 26 May 2018, 12:19 ]
Post subject:  Re: Baxandall circuit

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.
Baxandall Tone Stack.jpg
Baxandall Guts.jpg

Author:  mwhouston [ 26 May 2018, 18:26 ]
Post subject:  Re: Baxandall circuit

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.

Author:  john55 [ 27 May 2018, 03:27 ]
Post subject:  Re: Baxandall circuit

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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