DIY Audio Projects Forum

6CY7 Stereo Amp
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Author:  kidmoe [ 31 Dec 2017, 20:53 ]
Post subject:  Re: 6CY7 Stereo Amp

Suncalc wrote:
I just thought I'd mention that there is another output transformer from Edcor for this project that will give a little more lower end response. The GXSE5-5.5K-8 is a drop in replacement but has a rated passband 30Hz lower than the XSE10-5K-8 (40Hz vs 70Hz). Given that the XSE yields a lower -3dB frequency of about 32Hz in this design, I am guessing that the GXSE should give good performance down to at least 20Hz (I have not tested it).

And here's the best part, the difference in cost between the XSE and the GXSE is a whopping 38 cents (as of this writing). I was thinking about a pair of tiny 6CY7 mono-blocks. Maybe I'll give the GXSE5-5.5K-8 a try and see how it compares.

Hi Matt, Did you ever retrofit your amp with the GXSE transformers? I'd be curious to see what your impressions were...

Author:  Suncalc [ 31 Dec 2017, 23:05 ]
Post subject:  Re: 6CY7 Stereo Amp

kidmoe wrote:
Did you ever retrofit your amp with the GXSE transformers?
Not yet. I have two versions of the upgraded amp on the drawing board. One is a smaller amp with the same power transformer, the other is a pair of mono-blocks with tube rectification. I haven't gotten beyond the basic design stage with either yet. Maybe some time this summer.

Author:  stwh [ 13 Jan 2018, 08:00 ]
Post subject:  Re: 6CY7 Stereo Amp

Hi Guys. I am new to this forum and tubes. Great info here Thanks. About to build this amp but have the Hammond 369EX transformer. This PT has a center tap on the 6.3v secondary. Should I remove the 100ohm resistors and connect this to earth or a cathode or just ignore it.

Author:  Suncalc [ 13 Jan 2018, 14:07 ]
Post subject:  Re: 6CY7 Stereo Amp

Just omit the two 100Ω resistors on the filament lines and tie the center tap from the 6.3v winding directly to signal ground.

The two 100Ω resistors form a virtual ground for the filament circuit if the transformer does not have a center tapped filament winding. I actually prefer using center tapped filament windings if they are available.

Author:  stwh [ 13 Jan 2018, 15:08 ]
Post subject:  Re: 6CY7 Stereo Amp

Thanks Matt. Much appreciated. I will do that.


Author:  Renaissance Man [ 29 Apr 2018, 10:42 ]
Post subject:  Re: 6CY7 Stereo Amp

I have built up this amp as per the schematic except with a SS power supply. I use it primarily for my 32 ohm headphones in parallel with a 32 ohm resistor - so 16 ohm output load.

I quite like the warmth of the second harmonic distortion, but at times I find the distortion too high for my taste. I am wondering if there is something I can do to bring down the distortion a little without dramatically effecting the sound quality. I have toyed with a small amount of global negative feedback or perhaps changing the operating points of the tube?

Any advice would be appreciated.

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