Iron Pre Essentials Kits For The DIYA Store - Register Your Interest

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#2,066
tonyEE said:
Here's what you need to order... tell Giancarlo it's for an Iron Pre and he'll know how to finish it.

Heads up, I think they're still on their summer vacation.. Euros and their August.


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This is almost correct, the front panel customisation option should be "customized on one side of the panel" and the option for the rear panel should be "more than 20 holes". Everything else is correct!

As soon as I am back from Colombia I'll make sure to add a complete product to the store so it is easier for everybody to purchase the chassis without having to add the single customizations to your cart
 
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#2,067
Zen Mod said:
if there is sibilance, try loading output of preamp itself - resistor shunting output hot to GND (physically - either on pcb output pads, or on RCA/XLR outputs)

in cases where Rin of power amp is highish, some taming of autoformer can be good thing to apply

say (resistor) 100K and down - leave value which you like most
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So, I did an experiment, adapted a little box to dial in a shunt resistance from 100k down to ~55k, and later, from 50k down to a short. I didn't notice any convincing change in the sound until right before it cut out completely, when the shunt resistance was dialed close to zero. Maybe this shunt needs to be right on the secondaries to have an effect, idk, but I'll claim that a shunt halfway between the preamp and amp, with RCA cables in between, doesn't.

Then I got clever & put in my little old passive preamp after the Iron Pre and before the amp. That changed the sound & now I have two tone knobs to play with. But overall I'd say, leave it alone.
 

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#2,068
I'm, frankly, leaning to conclusion that - if there is any significant sibilance when Iron Pre is introduced in signal chain - better try what's happening with some other decent source

any possible rinzinging of Iron Pre itself can be tamed with RC cell loading of pre output, but it is impossible as general recipe, considering wast range of possible amplifier input impedances
 
#2,070
Zen Mod said:
I'm, frankly, leaning to conclusion that - if there is any significant sibilance when Iron Pre is introduced in signal chain - better try what's happening with some other decent source

any possible rinzinging of Iron Pre itself can be tamed with RC cell loading of pre output, but it is impossible as general recipe, considering wast range of possible amplifier input impedances
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yeah, so afterwards I hooked my Iron Pre up to a signal generator and oscilloscope. I didn't take any pictures, but I didn't see any evidence of ringing on sine or square waves up to about 28kHz, so I don't know what I would be trying to damp with an RC cell on the secondary. The rise of square waves at high frequency got a little delayed, but I assume that's just hysteresis in the core.
 
#2,071
" but I didn't see any evidence of ringing on sine or square waves up to about 28kHz"

Was the scope the only load on the preamp? If the preamp's ringing is susceptible to the load, would it be that the scope's load impedance is too high and tames the Iron Pre?

Maybe load the scope in parallel with your amp, the one that exhibits the "sibilance" and then take the measurement again?
 
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#2,072
ranshdow said:
yeah, so afterwards I hooked my Iron Pre up to a signal generator and oscilloscope. I didn't take any pictures, but I didn't see any evidence of ringing on sine or square waves up to about 28kHz, so I don't know what I would be trying to damp with an RC cell on the secondary. The rise of square waves at high frequency got a little delayed, but I assume that's just hysteresis in the core.
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What ZM and Tony said.

Regardless of measurements, simply do what you can to single out the IP as the source of sibilance.

Also keep in mind that it might also be so transparent that it reveals DAC or source issues better than other preamps.

If it is the IP, you have basically ruled out output transformer ringing, or? Next move i would imagine is to increase the input series gate resistor, first to 1k. If better but not perfect, move on up a bit more, not above 3K2 (quote MZM in private romantic Viber conference). Of course killing ZM’s preciousness of maintaining dynamics everywhere possible :rofl:

So, if your poweramp is a silly easy load (Aleph J, etc), try swapping power amps, or load the output transformers.

If suspecting oscillation between source and IP, increase input series resistor. If that doesn’t cure it, and the IP was done right, the issue may lie somewhere else in your chain.

And we all know, MZM is omniperfect, and so is therefore also the IP. So it can never be guilty of problems, only of revealing them :rofl:
 
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#2,076
Aaah,... the USPS... so up until last night they claimed my package would be here by 8/24 at 9PM

Now they show 8/28 by 9PM. And the package is:

Moving Through Network

In Transit to Next Facility, Arriving On Time

Heck, this is out of 1984's Ministry Of Truth. Just change the arrival time if you're late... simple as that. Erase the past.

Imagine, if I had stayed home just to receive a package.... what's the point of tracking a package when it's so inaccurate and there is NO responsibility for the shipper ??? ( UPS and FedEx are worse ).

It looks like my package spent three days stuck in the USPS Regional Origin Facility in Providence, RI...

One of these days, Amazon will spin off its "Amazon Logistics" and they will kill off USPS, FedEx and UPS.
 
#2,077
For UPS we have something called "MyChoice" where I have setup packets to go to a packet shop by default. I have two of those within 500m from where I live. Don't know if the packet show concept is known everywhere. They use various smaller shops, kiosks etc. for such purpose. FedEx has bad service so I avoid them. I have a number of times been forced to do pickup close to the airport at their local headquarter. DHL, GLS very nice with packet shop concept also.
 
#2,078
I get wines delivered... used to be FedEx and my wines would be on a truck for days... then I asked the wineries to change to UPS.

I have UPS hold the wines in their distribution center which is a few miles away from us.

USPS is normally better than either of the other two... but even so.
 
#2,079
ItsAllInMyHead said:
^ I've recommended that this be listed for intermediate to advanced builders. Hopefully, that will help.

With that said, the intention is to make it as accessible to as many builders as practical. Somewhere between spoon-feeding for a 'standard' build and allowing the flexibility for others to explore the vast options available to customize on their own. Given the relative rarity of parts, we don't want things going poof.

There definitely will be a step-by-step 6L6 guide to help everyone with the exception of the first 'early' builders. For those fine folks, we're here to help. The feedback for improvements is greatly appreciated.
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