Intact Audio

Yes, pro levels at the input but the ADC gets much less, I believe only a 5Vpp swing is max at the chip As for the digital in, I skimmed through that link and saw 2 opposing views, the guy who proposed it who admitted he was trying to do RF design work with only a multimeter, and Gordon Rankin who d...

I am interested in both inputs actually. I plan to use a DEQ2496 in front of the DCX for room correction. I'm pretty sure the analog in on the DEQ is the same as the DCX so it will work on either. I'll feed the balanced digital out of the DEQ to the DCX so a better digital in on the DCX would be goo...

can you post a schematic of your input hack? I understand you have to maintain a 2.5v bias on both input pins. My phono stage is transformer coupled out so I thought this might work. Straight to the ADC and bias through added resistors chosen to get the load you want on the phono. Get the 2.5V from ...

http://www.sound4sale.com/products/MVC.php I'm getting ready to buy one of these as my volume control solution, I hope. JJ pointed out it has input and output buffers but looks like you could easily bypass the input one. The output may need the opamp since part of the ladder it is the feedback for ...

After careful consideration it seems that a hard drive based server with USB feeding a USB DAC is the wave of the future, and since I don't currently have a CD player it seems like a great route to take. The digital data is error free if properly ripped and the jitter from the standard SPDIF interfa...

I changed the output stage of the phono to filament bias which lowered the output impedance from somewhere around 5-6K to probably less than 2K so I lowered the input impedance to my amp and the AVC I was trying now sounds much better. I’ve got a high quality stepped attenuator on the way so it wi...

Thanks Dave. That makes sense but it still amazes me that making these seemingly insignificant changes can affect the sound so much. Some days it drives me insane that there are so many variables and others I just enjoy playing with it. At least I'm to the point that if I never made another change I...

My cartridge is a Wilson Benesch Analog. As I understand it is a high end Benz (ruby?) mounted in a carbon fiber body of WB design. It has the same .35mV output as a ruby. A dcr of 10 ohms with a recommended load of < 20 ohms with a step up. That sounds dull to me so right now I have the secondary o...

My source has a 6c45 with a 1:1 transformer and a 120 ohm non-bypassed cathode resistor so I'm guessing around 5K. I'm not sure what the Rp of the tube is. The added 7H didn't do much for me. I haven't been able to find a sweet spot with the AVC. I was initially impressed with the transparency but I...

Up to this point I have not played much with restacking and gapping as I have been busy just getting my amps to the final (ha ha) design but I must say I am very suprised how much difference it makes. So far I have experimented with my AVC and mc stepups and the results have been positive. I also ha...

I'm not sure what version of the step ups I have here, came through Jeffrey, but I restacked them last night to go from 6x6 to 4x4. So far I like it better. Resolution has always been good but I was looking for a bit more warmth and this got that. Need to try more combos but it looks Jeffrey will be...

I looked through the forum and didn't see any discussion of this. With the Slagle interstage transformers I got it was recommended to experiment with different shims in the gap. With my AVC it was recommended to experiment with restacking the lams. I see others are reporting results from restacking ...

So right now the lowest useable tap is around -24 dB which is 1/16 of my 80H so about 5H. If I add that much to the bottom end then I would be starting roughly at -24dB and have 14 steps up to full volume. That doesn't seem as significant as I first thought it would. However, I do have a pair of 7H ...

are you sure that only a 6dB range of attenuation would suit you? Ok I'm trying to get my head around this. My initial assumption was the AVC is wound with an equal number of turns between steps, but if each step is 3 dB then math doesn't work that way.. Are the number of windings logarithmic as dr...

Here is the easy way to get a stop and not lose a position. Take off the back wafer. Get a small bolt and nut from your junk box. There is one postion that does not have a contact but has a small hole where one could go. Drill the hole a little bigger to accept your bolt. My picture shows the bolt s...

First, I've just started playing around with new AVC, stock 14 position. The stock butt joint was thin, I tried 5x5 and got fullness but a little shrill. I'm at 7x7 now and it seems about right. I'll try more later but stick with this for awhile. Anything below about halfway down just isn't loud eno...

I'm reasonably sure your hum is a grounding issue and not a shielding one. I would tend to agree but I believe I tried every possible combination of grounding but who knows. I can go back and run through it again. UPDATE: I tried your suggestion and it worked. I thought I had tried all iterations b...

I put a pair of your 1:26 step ups down the throat of my pipe today and even though they sound very good, I can't get the hum down to an acceptable level. It is better in the pipe but much louder than the Jensen JT-347-AXT that I have been using. Seated in my comfy chair the jensens outside the pipe...

I haven't tried it yet but it is built. from the inside out .. 2 foot length of 3" galvanized water heater vent from Home Depot .. bubble wrap .. 49% mu metal .. bubble wrap .. copper shield with grounding wire .. bubble wrap .. 80% mu metal I think I'll just mount my step ups to a piece of woo...

Hi Dave, I have the stuff (metal and MC's) from Jeffrey and hope to build one of these soon. It may be a few days but I'll report back on yours vs the Jensens I have now.

It looks like you may be getting a bit ahead of yourself as the time stamp on your post is tomorrow.

in the interest of a simple prototype, how about starting with a pair of the 14 step "kits" That sounds like an excellent idea. I'll get some relays and the other stuff and get started. This is the remote volume control I have. Starting over I would look for a cheaper way since the motori...

I bought a DACT remote kit that uses an Alps motorized pot. I now find that the pot has an imbalance of about 2dB at low to mid volume levels. My idea now is to use an LED bar graph driver like an NTE1508 in moving dot mode to switch relays. I plan to take the voltage that drives the pot, or use the...

My initial diagnosis of a weak 71A may have been wrong.The gain was low but I found one filament was running hotter than the other, 4.8V vs, 5.3V even though they were the same when I first set up the current sources. I then checked the 300B's and they too were off, 5.1 vs. 5.3. I trimmed the 300's ...

Well it looks like I'll have to look into the spice a little deeper. In the meantime while I had it on the bench to figure out why one channel was suddenly weak (71A dying) I measured the response of the new setup. I didn't plot the 6SL7 because after some listening last night I'm pretty sure I'll s...

I built this circuit in effort to understand the thin sound I was getting but I don't see why it was so. It does get a bit inductive on the bottom end but it doesn't look as bad as it sounded. Even though the inductor measures a flat ouput through the midband, I find it hard to believe on an intuiti...

When I was -1dB at 20Hz and 20KHz 280H is about 35K at 20Hz + the 5K or so from the 71A cathode R makes 40K. The output Z of the tube is around 8K 20 log 40/48 = -1.6 dB If I do the same thing with 100pF at 20KHz I get 80K 20 log 80/88 = -.8 dB Did I do that right? That's pretty close to what I meas...

Are you really Jeremy??? The circuit is exactly the same as the monkey, it is just drawn a bit differently. Plate of input direct to grid of 71A, from this common point through the choke to the voltage divider on the cathode of the 71A. The choke is not at AC ground, the plate of the input tube sees...

Raj, back up a few posts and look at the link to Jeremy Epstein's page. It does look wierd but it isn't unusual to direct couple a plate to a grid, I think you are looking at it backwards and it is easy to do so. The B+ for the input tube comes from the voltage developed across the cathode resistor ...

Here is the amp with the choke load, the new R load, and an F plot of the choke. The peak at 1KHz might explain a lot of what I was hearing but it is pretty flat when driven by 7K so I don't know. I got the 1800 ohms by pushing 5mA DC through it and measuring the drop across it. I figured the 280H s...

I’ve finally had time in the past few weeks to do some serious tweaking and listening. As a reminder my circuit has been a monkey 6SN7 direct coupled and Dave choke loaded to 71A and then Dave’s IT transformer to a 300B output. After my initial irrational exuberance about having the amp up and r...