SE 6CB5A amp with 6N7 driver

[pso]

Hi,

In the version of transformer coupled, all oil caps can be 50uf?

 

[Vinylsavor]

Yes, you can use 50uF caps

Thomas

 

[pso]

Hi Thomas,

The transformers are here,

The PT is really heavy (17-18 lbs.), I was doing some test with the primary (0-220-230-240V) and the two secondarys, and get any voltage, very, very flexible.

 

[Vinylsavor]

Hi!

Glad you like the power transformer. Let me know if you have any questions while building the amp.

My small mono blocks based on the RC coupled cirtcuit are com,ing up soon

Chassis are already made:

http://imageshack.us/a/img832/6084/mono1n.jpg



Best regards

Thomas

 

[merlin el mago]

Thomas the link provided don't operate.

 

[Vinylsavor]

Try again, I corrected it, should work now, is just a link to a photo

 

[mwiebe]

Thomas,
Nice looking amp. Is that a full wood cap or wood covering a metal cap? I expect you are hiding your ASC caps under there.
Matt

 

[Vinylsavor]

Hi Matt,

no ASC caps in this version. This is going to be a low cost implementation, so no oil caps but electrolytics. The wooden cap will cover the power transformer. The first versions of the wood cover is not made of solid wood, it is veneered. But I plan to get them made from solid wood like the chassis frame

Best regards

Thomas

 

[merlin el mago]

Try again, I corrected it, should work now, is just a link to a photo

Thanks, I always enjoy looking your work.

 

[larryldspkr]

I like the idea of building mono blocks, smaller power transformers! I listened to Jim O's amp at my house driving a pair of Tang Band 8's in a mltl, very impressive!!

Larry

 

[Vinylsavor]

Hi!

I just uploaded an article on my blog with a schematic and detailed explanation of the low cost version of the 6CB5A amp:

VinylSavor: Low Cost Single Ended 6CB5A Amplifier - Part 1

More articles will follow with detailed photos of the building process.

Best regards

Thomas

 

[mwiebe]

Thomas,
The ASC oil caps you use are not expensive but they do take up real estate. Why not ultrapath connect the electrolytics? You could step them down to 30uF though the voltage rating would have to go up. Just curious.
Matt

 

[Vinylsavor]

Hi Matt,

as this is supposed to be a low cost design, each part needs to be looked at. And while the ASCs are not very expensive, it adds up and as you mentioned they need real estate which drives up the chassis cost. You could argue the same about interstage transformers, they are not that expensive.

The same for ultrapath: it would add to the cost significantly since it requires decoupling of driver and output stage to be cost effective. I already presented a design which is a step up in cost and a significant improvement in sound performance. It can be found where:

VinylSavor: Making of a SE 6CB5A amplifier: circuit

At the end everybody can make his own choices. Since I usually show designs with little compromises, I wanted to show an amp that is at the lowest possible end of the cost ladder but still providing good sound.

Best regards

Thomas

 

[mwiebe]

Thomas,
I guess I should have gotten to the point. I like ultrapath as well but I have never listened to an electrolytic in that position, I was curious if you had. I have never A/B'ed electrolytic bypass with electrolytic ultrapath. I've tried MKPs as ultrapaths but didn't like the sound.
Matt

 

[Vinylsavor]

Hi Matt,

the main reason I use ultrapath is to avoid the electrolytic cathode bypass cap in the signal path. I see no reason why to do it with such a design with electrolytics. As mentioned before: ultra path requires added complexity. In an amp which is that refined I would not use electrolytics at all.

Best regards

Thomas

 

[Hylle]

Hi Thomas, if you have a electrolyt as the first cap in you powersupply after the gratz bridge, and then isolate it from the amp circuit, with a coil and proper decoupling, will you still be able to hear that first electrolyt?
I guess the function of the coil is as much to prevent the music signal to go though the electrolyt as much as it is there for noise filtering, or am I completely off hear?
By the way I love the way you build you designs, but they become so expensive....

 

[kstagger]

Thomas - for the Mk 2 version of your Octal preamplifier, what manufacturer for plate chokes did you use for the 6SC7 / 6N7 stages? The schematic said 800H.

 

[Vinylsavor]

Hi!

Thomas - for the Mk 2 version of your Octal preamplifier, what manufacturer for plate chokes did you use for the 6SC7 / 6N7 stages? The schematic said 800H.

For the first build I used some custom chokes. Then switched to Lundahl LL1667/5mA which have about 600Hy.

There is a thread about this preamp :

http://www.diyaudio.com/forums/tubes-valves/177988-octal-preamplifier-phono-section.html

Best regards

Thomas

 

[Vinylsavor]

Hi!

Hi Thomas, if you have a electrolyt as the first cap in you powersupply after the gratz bridge, and then isolate it from the amp circuit, with a coil and proper decoupling, will you still be able to hear that first electrolyt?

You will probably get different opinions on that. I would say the electrolytic would not be very audible. But I haven't tried. I either built all oil caps or all electrolytics

Best regards

Thomas

 

[Hylle]

Ok, Thomas. I thougt this was the way you build you most simple/cheaper amps. I will of cause try it out my self.