Preamps... nothing is perfect.

Thank you very much. Yes, I find my CAT amps fairly neutral, especially for tube amps and attribute a lot of that to the KT 150s. And, my sound now with the passive pre is absolutely dry and analytical.

I have never heard the Koda myself, but of course have read wonderful things about it. I'm not sure it's within my means.

It's very interesting to hear from someone that uses CAT amps with a non-CAT preamp.

I have been using a heavily modified Jadis JP 80 MC with the CAT JL-2 Black Path for nearly 4 years. It has the body I greatly appreciate in tube electronics along with excellent frequency extension and delineation. For my tastes and associated equipment this combination has been the best so far.
 
Received my Pass XP-22 pre back from repair yesterday (Saturday), and I am really enjoying it. For three weeks I had to use my Cambridge Audio 840E preamp, and while it was superb, the Pass crushes it. The lower noise floor, the lack of distortion, the better level of control with the Pass is amazing. Highly recommended.
 
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Bud, i'm glad to hear you've got your Pass preamp back & it s playing glorious music again. Nelson Pass is a legend in the Industry, and the XP-22 appears to be the sweet spot in the XP range anyway. Pitting your preamp against Cambridge Audio is a bit like clubbing a baby seal, lol! :D
 
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I've just completed a new passive line stage, this time utilizing the silver AVC from Dave Slagle. I reclaimed a simple wood chassis, and designed the front and rear panels with Front Panel Express. The input selector toggle switch has gold plated silver contacts, and the input and output RCAs are Furutech FP-901R (I like these in terms of quality / robustness over WBT chassis connectors).


cNU9QBJ.jpg


I'm not sure why, but perhaps because of Jack Roberts's copper vs silver Emia comparison, I was expecting subtle changes vs my previous copper unit. Well, changes are not so subtle after all. As I think @CKKeung has mentioned in regards to the Bespoke TVC, the differences are readily apparent. Clarity, separation, air, nuanced micro detail... All a step up. Not a surprise really, but the size of the step was somewhat surprising to me. Also a surprise was the improvement in the low end in terms of it's solidity, presence and articulation. People who worry about silver being lean need not worry in this case.

Now, I had decided to go with all Neotech solid silver hookup wire to round out the silver experience. And dspite all the good things mentioned above, I also noticed a tonal color shift particularly in cymbals and horns; a slightly bleached tendency that I didn't feel sounded right. Well it got me to thinking about @DaveC and his comments on silver vs his D4 timbre, and I wondered how much influence the short stretches of internal hookup wire could actually have. Luckily I had his D4 wire in my previous AVC, so this morning, I extracted it and moved it in to the new unit. I left the input wire from input RCAs to AVC as solid silver, but combined 4x of the D4 wire per channel from AVC to the outputs. Boom. There's the hint of sweetness (is how I'd describe it) back and to my ears, more correct color in the treble region. This stuff really does a good job, and I think it is the icing on the cake. Now on to more listening and discovering.
 
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Baselio, thanks for your report. Do you pay attention to wire direction when doing the internal wiring?

Is the silvery bleaching now gone? I must be in a minority but never really warmed up to the sound of teflon insulated Neotech.
 
Interesting article and nice project. I ran a more simple 48 step elba pot before I went back to active pre. But generally with passives, I find you need a good drive stage with lots of juice, 6v at least, or it can sound flat and anemic.
 
@analogsa

The touch of bleach has given way to better tonal color variations especially with cymbals. I suppose if I wanted further color, I could rewire the input side also. But it's sounding very natural to me now. Dave's D4 wire is also Neotech with teflon but is the custom silver alloy with gold. I didn't care about wire direction, though when I cut the wire into individual runs, I did label each one at the source end for soldering. So I suppose all segments actually are oriented in the same "direction". Mainly though, I just tried to keep L and R channel wires spread apart. I had thought to try the Jupiter silver hookup wire in cotton or silk. But, I'm only willing to perform surgery on this thing so much. It's a bit tedious and it's sounding incredibly clear and articulate.
 
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Interesting article and nice project. I ran a more simple 48 step elba pot before I went back to active pre. But generally with passives, I find you need a good drive stage with lots of juice, 6v at least, or it can sound flat and anemic.

The AVCs don't sound like pots in that regard.
 
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I find you need a good drive stage with lots of juice, 6v at least, or it can sound flat and anemic.

What on earth is "6v"?

Transformer/autoformer based attenuators need only a source with a reasonably low output impedance.
 
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6V is high for typical "consumer" line level. And most amps will achieve their rated output with around 1V input (+/-), while AVCs solve most impedance issues between source and amp. Even a couple K output impedance can be ok.
 
I've just completed a new passive line stage, this time utilizing the silver AVC from Dave Slagle. I reclaimed a simple wood chassis, and designed the front and rear panels with Front Panel Express. The input selector toggle switch has gold plated silver contacts, and the input and output RCAs are Furutech FP-901R (I like these in terms of quality / robustness over WBT chassis connectors).


cNU9QBJ.jpg


I'm not sure why, but perhaps because of Jack Roberts's copper vs silver Emia comparison, I was expecting subtle changes vs my previous copper unit. Well, changes are not so subtle after all. As I think @CKKeung has mentioned in regards to the Bespoke TVC, the differences are readily apparent. Clarity, separation, air, nuanced micro detail... All a step up. Not a surprise really, but the size of the step was somewhat surprising to me. Also a surprise was the improvement in the low end in terms of it's solidity, presence and articulation. People who worry about silver being lean need not worry in this case.

Now, I had decided to go with all Neotech solid silver hookup wire to round out the silver experience. And dspite all the good things mentioned above, I also noticed a tonal color shift particularly in cymbals and horns; a slightly bleached tendency that I didn't feel sounded right. Well it got me to thinking about @DaveC and his comments on silver vs his D4 timbre, and I wondered how much influence the short stretches of internal hookup wire could actually have. Luckily I had his D4 wire in my previous AVC, so this morning, I extracted it and moved it in to the new unit. I left the input wire from input RCAs to AVC as solid silver, but combined 4x of the D4 wire per channel from AVC to the outputs. Boom. There's the hint of sweetness (is how I'd describe it) back and to my ears, more correct color in the treble region. This stuff really does a good job, and I think it is the icing on the cake. Now on to more listening and discovering.
Hello Bazelio,
Congrats!

I think your diy silver sagleformer AVC passive preamp is very similar to those of Emia, bcos the silver AVCs are the same.

Share with you an experience:
A frd of mine got MBL Corona preamp and 2 Corona mono amps to drive a pair of Verity Audio floorstanders.

The overall effect was not bad.
But when he replaced the Corona active preamp by a borrowed Emia single-end silver AVC passive preamp, his system was transformed.
There was huge improvement in resolution, freq extension and surprisingly both micro- & macrodynamics!

This made him to order an Emia balanced silver AVC passive preamp at once!
:D
 
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@CKKeung thanks! Indeed my DIY is the same as a silver Emia (without remote) since the AVC itself is identical.

New observation: The expansion of sound stage width and air is interesting. I almost feel like I can walk around in between the instruments on some records. Whereas before, left to right, things were more compressed together. On the one hand, this creates an interesting sound scape. But on the other hand, on some records, you now get empty regions on the stage. But, for things like close mic'd small jazz ensembles, I guess this is how it would be reproduced. Switch to a simple duet, and you can clearly separate each singer's voice and focus on it. This sounds more realistic to me.
 
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@CKKeung thanks! Indeed my DIY is the same as a silver Emia (without remote) since the AVC itself is identical.

New observation: The expansion of sound stage width and air is interesting. I almost feel like I can walk around in between the instruments on some records. Whereas before, left to right, things were more compressed together. On the one hand, this creates an interesting sound scape. But on the other hand, on some records, you now get empty regions on the stage. But, for things like close mic'd small jazz ensembles, I guess this is how it would be reproduced. Switch to a simple duet, and you can clearly separate each singer's voice and focus on it. This sounds more realistic to me.

The single-end Silver Emia gave a sound scape similar to your diy version.

My frd's balanced silver Emia (4 AVCs inside) gave even better dynamics and filled up those empty stage regions more.
 
The single-end Silver Emia gave a sound scape similar to your diy version.

My frd's balanced silver Emia (4 AVCs inside) gave even better dynamics and filled up those empty stage regions more.
That's interesting that the balanced Emia has that effect. I guess there are other variables between those systems too? Balanced wouldn't be an option for me. I wonder if there's a "break-in" period with these, too. I didn't put the previous one through the paces early, so if sound changed slowly over time I might not have noticed.
 
Good to hear your experience with the silver AVC and also my silver/gold wire. :)

I'm looking forward to building another pre using them, it will have a tube buffer as well, but I'll take @CKKeung 's advice to install a switch so it can be used with or without the tube buffer. I'm a proponent of buffering and feel it can be better in many circumstances but not all.

Also, I do feel like a soundstage with "air" and the ability to convey a blank space... if that's what's on the recording... is very good and not something all systems are capable of.
 
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Also, I do feel like a soundstage with "air" and the ability to convey a blank space... if that's what's on the recording... is very good and not something all systems are capable of.

It's the last bit of distraction I have after the switch to silver AVC. I tend to think it's a more accurate and precise rendering of what is contained in the source material. It's very dependent on the record and ultimately the recording and mastering. Clapton's Unplugged was a new experience yesterday during my listening session. This record demands a high resolution system and it was not previously as clear to me that he must be changing positions on the stage at certain times during the performance, or something in the mastering process didn't maintain a stable location of his voice and guitar on the stage (varying crossfeed??). Whatever the case, it's an interesting experience. With almost every record, I've found myself looking up and saying "wait a second...".

@DaveC other than possible tarnishing, what is your experience with silver in teflon vs silver in unbleached cotton or silk. So just purely sonic comparinsons.
 
My advice is simple: hang on to what you own today but mod it with top parts. And the more top parts you put in (pure copper foil caps, top Furutech NCF inlets, input/output jacks, internal wiring, etc.), the higher SQ you will get. That will make you one happy audiophile with some change left in your wallet...
 
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It's the last bit of distraction I have after the switch to silver AVC. I tend to think it's a more accurate and precise rendering of what is contained in the source material. It's very dependent on the record and ultimately the recording and mastering. Clapton's Unplugged was a new experience yesterday during my listening session. This record demands a high resolution system and it was not previously as clear to me that he must be changing positions on the stage at certain times during the performance, or something in the mastering process didn't maintain a stable location of his voice and guitar on the stage (varying crossfeed??). Whatever the case, it's an interesting experience. With almost every record, I've found myself looking up and saying "wait a second...".

@DaveC other than possible tarnishing, what is your experience with silver in teflon vs silver in unbleached cotton or silk. So just purely sonic comparinsons.

IMO the wire in cotton is the best, but the difference isn't much and isn't worth the tradeoff. If you want to do better vs teflon I'd consider getting some oversized teflon tubing and filling it with an inert gas instead of using bare wire in cotton, as it will definitely corrode. Wire in inert gas is the best solution but a PITA.
 
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Excellent effort Bazelio, it’s always good to see diy efforts getting their rewards. I too have a similar project in the pipeline but with tube buffer / headphone amp.

If you compare cotton v silk tubing, the latter is more transparent and pure sounding. Cotton gives some warmth and midrange body to the presentation - which is why many use it with silver - but it also leaves some dryness and fuzziness.
 
With my schedule over the next few days, I won't be able to listen to music until Saturday. So I decided to test observations I've read that transformers or autoformers have a "break in" period, after or during which they will sound different.

lOtUNrT.jpg


I'm running a varying frequency and amplitude sweep. Amplitude is capped at 5V pk-pk at the autoformer inputs. The fundamentals sweep 10 Hz to about 25 kHz with different waveform patterns (square, sawtooth, sine, etc) warble tones, complex waveforms, and noise with high frequency content out to 100 kHz. I'll run this through the AVC for the next 4 days. It should provide a rigorous break in. Saturday after about 100 hours, I'll try to detect audible differences with the AVC back in my system.
 

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