Search found 165 matches

by Wolfgang
Tue Jul 17, 2018 4:18 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

I don’t want to sound like a party pooper….but this seems to be a different amp with a different sound. The original idea was to match an amp design with a speaker impedance/sensitivity (15ohm Lowther DX/EX4) which included the specific CDF of the speaker. From there the amp was set/tuned to sound b...
by Wolfgang
Thu Jun 21, 2018 7:40 pm
Forum: Everyones Projects
Topic: Tweeter Amp for OB or Horns
Replies: 155
Views: 23442

Re: Tweeter Amp for OB or Horns

Thanks for the detailed answers, Marc. Some time back I was considering to use a “tube only” active x-over for my Klipsch La Scalas but I couldn’t find any satisfying (simple) practical solution. So I am still driving them with 3 fullrange OTLs and a Behringer Ultradrive Pro which is not such a bad ...
by Wolfgang
Wed Jun 20, 2018 11:56 pm
Forum: Assorted Stuff
Topic: Ground Loop
Replies: 15
Views: 3208

Re: Ground Loop

I use a polarity tester to find the correct position for the power plug with less hum if nothing helps and everything else has already been done/checked. Even without disturbing audible hum it can improve sometimes dramatically the SQ.
Polarity tester.png
by Wolfgang
Mon Jun 18, 2018 4:04 pm
Forum: Everyones Projects
Topic: Tweeter Amp for OB or Horns
Replies: 155
Views: 23442

Re: Tweeter Amp for OB or Horns

IslandPink, I was wondering what could have been the reasons for some of the choices you have made in this circuit. For example the ECC40 gets a CCS but the 45 doesn’t. I would have expected it to be equally important there (constant current sink). How do you calculate the AC load line with a CCS, a...
by Wolfgang
Fri Jun 08, 2018 9:32 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

True but very hard to imagine from where I am sitting (sweet spot).

I think I should upload a recording so that everyone on this forum can get a picture what I am talking about.
by Wolfgang
Fri Jun 08, 2018 8:39 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

And to change the sound of this amp as it is now would be such a loss as it exudes reality of music. Incredible dynamics, lightning fast transients against a pitch dark noise free background. It doesn’t get better and it seems to have limitless power. If I needed it to drive 8 ohm speakers I would s...
by Wolfgang
Fri Jun 08, 2018 3:53 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

Maybe it's easier to find the right answers, Ray, if we reformulate the question a little? What goal(s) do you want to achieve using two regulators for the 6C33? Is it rather an aesthetic issue that you don't like to work with clumsy chokes and big caps or are you concerned about how mains voltage f...
by Wolfgang
Tue May 22, 2018 8:53 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

I finally could listen for the first time with the finished amp in my main system. After 20+ years of wasting a ton of money in the Highe-End scene and building my own equipment for more than 10 years I am still speechless and wondering what to say about this experience. What I can say is that this ...
by Wolfgang
Wed May 16, 2018 4:28 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

I simply try to follow the better argument, Nick. Especially your last explanation has helped me better understand your point of view. Funny, that it was a misunderstanding of what I wanted to say that brought it up. Why I mentioned the voltage regulator was to point out that it doesn’t help to disc...
by Wolfgang
Tue May 15, 2018 4:30 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

I thought we were talking about grid current that cannot sufficiently flow between grid and the cathode because of Rg (grid leakage resistor) being too high? Every valve passes this grid current, positive and negative, which evens out at some point and then the positive grid current is dominating. T...
by Wolfgang
Tue May 15, 2018 3:11 am
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

I think we need to be more specific if we have this interesting discussion. The only problem I can think of with Rg being too high is that the grid voltage can become positive (bias plus signal) and grid blocking would occur. The grid voltage would run away to positive and stay positive under these ...
by Wolfgang
Mon May 14, 2018 4:04 am
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

For matching the 6C33 OTL with the speakers I measured the CDF (critical damping factor ) for the Lowther DX4/15 ohm in my C-horns. At 2,5 ohm it would be ideal but even within the range of up to 9ohm it look pretty good. And 6ohm output impedance I could already achieve with the test version by add...
by Wolfgang
Tue May 08, 2018 11:47 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

You mean something like that (ignore the IMC part)?
by Wolfgang
Tue May 08, 2018 5:02 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

Ok, got it. “Grid blocking’ shouldn’t be an issue with CCS but I’d rather be safe than sorry so the 100k instead of 470k is some compromise that doesn’t hurt. To use a coil/choke (I use chokes wherever I can because they add something wonderful to the sound of tubes IMO!) instead of a resistor could...
by Wolfgang
Mon May 07, 2018 8:59 pm
Forum: Everyones Projects
Topic: 6C33C SE-OTL Project
Replies: 114
Views: 19104

Re: 6C33C SE-OTL Project

Hi guys, I thought it’s about time to register with this forum. This OTL- project on which I am working together with Ray could become even more interesting in combination with the impedance multiplier circuit. As it is right now these OTLs only work with 15ohm or higher impedance speakers. A first ...