[Nils]

I'm loving my like-new TAP-X preamp.  Everything sounds so much more natural than my old Bel Canto.  But I am noticing that there's not as much weight in the lower registers.  I know that transformer-based amps definitely benefit from many many hours of burn-in; are autoformers the same?

Also, would running the preamp at the lowest volume setting accelerate break-in (seeing as it's using the most winding possible?).

I did change my bass amps over from Furutech outlets to Oyaide R1s to make room for the wall wart, but I might change them back and see if that might be part of the cause? 

Thank you!
-- Nils

[John Chapman]

Hello!

I do get reports that they continue to break in for some time - although I have not listened to a full break-in cycle for many years. I tend to just burn them in here for a time on my burn-in setup then do listening tests then ship so I can't comment on just what changes to expect. Glad it has been fun in most ways and hoping the low end fills out for you!

Thansk!

John

[anubisgrau]

Wouldn't a missing weight in low register be a clear sign of an impedance mismatch between the source and the power amp?

I have a DAC with 2.8k output impedance and I'm very reluctant using non-bufferred passive preamp. Is there a trick (lamination maybe) how to sort this out with Slagle AVCs?

[John Chapman]

Hello!

That is a good point - we can check your sources out if you'd like. Your 2.8K is a good example - it is higher that I would want to see for sure. I like to keep things below 600 ohms or so since that is the highest imp I run here personally.

Also for break-in I do happen set at some lower level if leaving it running - with the autoformer the whole coil is always seeing the signal from the source so the level is not critical.

Thansk!

John

[Nils]

My Marantz SA-11s2 has these output characteristics, according to Stereophile measurements:

The level from the balanced XLR jacks was 4.4V with SACD and Filter 1 and 2, increasing to 5.23V with Filter 3. With CD, the maximum balanced level was 4.8V with Filter 1, 4.95V with Filter 2, and 5.0V with Filter 3....The unbalanced output impedance was a low 46 ohms at high and midrange frequencies, rising slightly to 52 ohms at 20Hz. The balanced impedances were exactly twice these figures, as expected.

92Ω-104Ω seems fairly benign.  My active crossover's input impedance is 30kΩ.

It's not unpleasant, or even lean.  It's just less than my old active Bel Canto PRe1 (a very fine preamp but nowhere close to the TAP-X in terms of transparency and dynamic immediacy).  The TAP-X has a very addictive clarity.

-- Nils

[John Chapman]

Hello!

Those impedances are just about perfect so no need to worry about that.  Time and maybe a bit of system fiddling will get you there. Does not sound that far off what you are after and glad you are enjoying the overall sound. You are addicted to just the same quality I like in the Daves autoformers - that "transparancy and dynamic immediacy"  is just what I get here too.

Thansk!

John

[Jeffrey Jackson]

Wouldn't a missing weight in low register be a clear sign of an impedance mismatch between the source and the power amp?

I have a DAC with 2.8k output impedance and I'm very reluctant using non-bufferred passive preamp. Is there a trick (lamination maybe) how to sort this out with Slagle AVCs?

ok... 2.8k is on the high side for what is out there on the market... but I bet it will be just fine.. I know John doesn't want me to post this, but you can get them stacked 1x1 for extreme applications... the formula for low frequency rolloof is:

impedance/(2*Pi*inductance) = -3dB frequency...

my memory is fading, I think John's stacking spec is 100 henries... 6x6... so that would be -3dB at 4.5Hz.. -1dB at 9Hz... plenty for me... don't forget this is in parallel with the input impedance of the amplifier reflected through the volume step's ratio... so it really only changes things if you listen to the top three "clicks"...

hope that helps?


so the numbers posted of 100 ohms feeding the 30k ohm amp through the autoformer certainly meet even the high criterion of 10:1 source to load... 


oh.. and I have noticed them sounding slightly thin when new.. not sure why, but it is there...

Peace,
Me

[John Chapman]

Hello!

No problem posting information here - That's what the forum is for! I do tend to be conservative about specs and always want to make sure we are well within what theory says should work fine. I have Dave stack 3x3 (or 4x4 - can't recall right this minute since the decision was some time back) as standard - In my testing I found that the best combo of sonic performance and gear compatibility. Obviously for finished pre-amps I had to choose one stacking arrangement rather than get'em all stacked differently..... 3x3 is a bit higher inductance and therefore it is a bit easier to drive than 6x6. For most gear (like the 100 ohm impedance of the Marantz player) either that or 6x6 would be easy sailing load wise.

Thansk!

John

[megawatt]

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Re: TAP-X / Slagleformer break-in
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Hi guys I bought a slager pre from Larry Moore I tried everything to rid a hum ground loop.. maybe its the radio shack adapter I am at the point of giving up maybe it will match someone else system.. This is my last resort ... Would anyone be kind enough to help me with this issue thanks   

[John Chapman]

Hello!

Call me tomorrow and we'll work through it. Larry is a great guy who builds really nice stuff. I expect we can get it quiet. Never met a system yet that could not be made dead quiet!  I'll be out Wednesday until afternoon west coast time but call later in the day at 604-538-9812 and I'll dive into it with you.

Thansk!

John