Intact Audio

Never mind about my question. Back in 2011, you commented on the merits of different OTL designs, that the inverted 6AS7 SE amp was not as good sounding as the 5687 amp. It is interesting that in your writeup about inverted tubes, you mentioned that the EL 509 might be a good tube for an inverted tu...

Hi Stephie, I would like to build an OTL amp to see what the OTL hype is all about. After reviewing different designs, I think I like your 6AS7 design the best. The great thing about inverted tubes is that they don't require as many tubes, and don't use as much electricity that would heat up the roo...

Oops, I remembered the schematic wrong. There are two coupling capacitors in the signal path and an input capacitor. All are necessary. This is one downside of this design, however, Stephie's comments on its sound quality are impressive. I analyzed the power draw for the circuit and I estimate the p...

Thanks for the very rapid reply! I definitely do not want a whole house heater! I have your writeup on the 6CG7 into 5687 OTL including a schematic. I need to study this a bit, but the electrical demand seems to be quite modest for an OTL amp. You even modeled the tube performance inverted! - very l...

Hi Stephie, I admire your engineering ability. I have 15 ohm Lowthers which are a good match for OTL amps. Many of the OTL designs have compromises that I would not like to live with. I recall that you worked on a SE OTL design about a decade ago. Did you ever finish off that design? I imagine that ...

how did you wire the outputs as autoformers? is it parafeed ? Yes, the outputs of my SE amps are parafeed (Magnequest permalloy transformers). I moved the DC blocking capacitor to the plate of the tube and connected the other end to the + leg of the transformer primary. I then connected the - leg o...

I just wired my the output transformers of my SE amps as autoformers and noticed a noticible improvement in sound quality. There is increased resolution (more transparent) and increased dynamics. :D So I then wondered, :?: why not wire the output transformers of my SACD player as autoformers? This s...

I finally removed the small inductors replacing them with 150 ohm nude Vishay resistors. Several have commented that these are the most transparent resistors that they have tried. Any loss in transparancy is very, very small with these resistors so it was a good deal. If I turn my preamp all the way...

I understand better now.

What player do you have?

Retsel

I worked with Mr. Slagle on adapting a transformer to my Sony DVP-S9000es SACD player. The long process of how I adapted a transformer to my player is here: http://www.intactaudio.com/forum/viewtopic.php?t=12 In looking at what you want to do, I suggest trying to configure the simpliest configuratio...

There are no new developments with respect to the player. I actually have not removed the RF inductors yet as they are not too intrusive. I still think that the player might be a little bit better in my main system without them, but I have been working on a new speaker system. My tray for this playe...

I purchased 16 of the 4.7 uH ferric inductors and when they arrived, I put them in the player wiring two small inductors per leg. Thus each leg coming off the VC24 chip had two inductors between the VC chip and the transformer. This gave somewhere around 90 ohms of resistance (or a little more) at 7...

at the frequencies in question, any capacitance might appear as a short. what you talk of sounds similar to a high GM tube oscillating. Maybe a ferrite bead with a few turns of wire in each leg of the transformer will do the trick.. or a small Rf choke. I am now all jazzed up about trying RF chokes...

I think I found the reference which the guy I quoted asserts that Thorsten says that a 40K:40K transformer works for digital. The reference is here: http://www.fortunecity.com/rivendell/xentar/1179/theory/vasfda/vasfda.html and the quote, in which Thorsten is actually praising the merits of another'...

My inital text: I tested the input DC resistance of the preamp, which has a simple resistive pot, and I measured 22 kohms at a range of volumes. Thus, my theory is this: The impedence that the VC24 chip sees is a combination of the DC resistance of the transformer, the inductive load presented by t...

I picked up some smaller filter capacitors and put them in. I have 4.7 picofarad caps across the entire secondary and 2.7 picofarad across the center of the secondary to the ground leg. This seems to result in better air with the music and hiss does not seem any lounder so I am probably at the best ...

I had the chance to do some significant listening of the player over the weekend. It does sound really, really great :P !! As I noticed, there is some minor hiss when playing CDs at very high levels, although it was acceptable by me and my listening buddy who listens to vinyl all the time (some may ...

The difference is amazing when the many active devices in the output stage can be bypassed. This player I am modding has the mods from an earlier Dan Wright modification, including ultrafast diodes, power supply capacitor upgrades as well as upgrades to the capacitors near the VC24 chip, and Refernc...

...and the Academy would like to thank Dave Slagle, Dave Cigna and others behind the scenes on the Intact Audio magnetics team.... OK, so I am a little ahead of myself... I could not wait any longer. It was between moving the fishtank and switching in the new transformer bobbins, and switching in th...

The Easter bunny (yep, I saw him myself.... :shock: (actually I suspect that it was Slagle in the flesh/fur...)) delivered a package yesterday which contained two newly wound bobbins with two separate windings each. Nervously optimistic about the likelyhood that the Holy Grail of magnetics may have ...

I have one of the replacements wound, hope to get to the other tonight. they are on a split bobbin so the primaries are isolated from each other, this will prevent the capacitive coupling between them that could be the cause for the lack of load at high frequencies. Now I get it.... COOL!!! Can I a...

"this suggests to me that the two outputs do indeed need to be independant of each other. (probably only at the sample frequency) and for the most part, the quadfilar wire does not acheive this (hence the need for resistors) so lets make a jump and do the revision the "cigna" way he ...

With my wife out of town over the weekend, I played around with the player some more and did a bunch of listening. I did the following: I wired the two primaries together in parallel with both sets of VC24 outputs wired together (after the resistors of course). I did not detect any change in the sou...

"so maybe adding some DCR to the transformer primary will do the same thing. it could be that the capacitance across the primary is a short at the sample frequency so simply adding DCR will not solve the problem... but then maybe a HF choke can be used. to get 1K at 2mkz doesn't take much. it a...

Apparently the resistors (150 ohm) in series with the VC24 chip output works wonders for regulating the chip as there is virtually no hiss when playing CDs (I did not have the chance to try a CD yesterday). Coooooollllll!!!!!! :P (You were right Dave Cigna, although it is not clear to me yet whether...

I wired some resistors in the signal path between the VC24 chip and the transformers. I used the existing resistors which Sony uses there which are 150 ohm and they appear to be metal film resistors. Whereas I was taking the signal from the input leg of the resistor after the VC24 chip, I am now tak...

Dave you were right about checking out the DIY forum. :P See these threads: http://www.diyaudio.com/forums/showthread.php?postid=255161 http://www.diyaudio.com/forums/showthread.php?s=&threadid=42441&highlight= http://www.diyaudio.com/forums/showthread.php?s=&threadid=42202&highlight...

"As far as I know, it's always a bad idea to connect the outputs of virtually any SS circuitry directly together, particularly bipolar, no matter digital or analog. The first thing they teach you in EE college is not to connect the outputs of digital chips together. (Not that I've gone to EE co...

"It seems like we're going in circles here. First off, I can't get rid of the nagging feeling that nobody here has any real experience with the VC24 chip or any other chip for that matter. Not sure what to do with that knowledge.... just wanted to point out that no matter how much we think abou...

Thanks Dave C. re the impedance and the capacitance. I am still grasping with the values (your reasoning does not describe why there would be a two order of magnitude difference in capacitor values unless if the chip's output impedance is as low as 0.8 ohms), but regardless of the values needed, I j...