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

[Ixnay]

I look forward to seeing updates on a decent build such as this.

 

[Zen Mod]

Thanks, that's what I was going to try, but given the work and effort that's gone into the design, I thought it was a bit simplistic.

well, either solder parallel wire connector to connector, or solder pairs of thin wires to pcb and route them to connectors back

as it is, adding another set of pads on alrady crowded pcb was ....... just asking for troubles

smaller pads are always that (trouble, being more fragile), and I was thinking that even Greenhorns are going to build this one

 

[jamayfie]

I think C18 may be backwards.

 

[SteveVulture]

Has anybody tried things like Z foil resistors in comparison to metal film in the gain stage ?

 

[Zen Mod]

there is no gain stage, per se, in IPre - where you have any resistor involved

anyhow, gate stopper resistor is in signal path

and gate shunt resistor is sorta in signal path

and trimpots are in signal path

feel free to change them all to ZFoil, and inform us of your finidings

but count on fact that you need to confirm difference between stock and ZFoil versions with proper DBT ..........

so you need to build two identical IPres

 

[SteveVulture]

I was going to leave left channel stock and modify the right 😏 I'm not sure I'll ever be able to hear the difference between a foil and a metal film resistor, I'm probably too old but I figure if I make enough small component choices, using the best parts I can afford, then there has to be an accumulated positive difference, plus I'll know I've done the best I can.

The trim pot - you mean this one ? https://www.mouser.co.uk/ProductDet...05320R0000J0L?qs=HmZfUfC6eKqLCu%2B%2BrfRDig==

20 ohms, 21 turns, 25ppm/*C, foil. Too expensive for me unfortunately. Once its built I'll consider making a small pcb to take SMD resistors, series and parallel on each leg, so I set a permanent value and remove the pot.

I've ordered the balanced Iron pro essentials, an Aleph J and a M2X board set, plus some jfets. Going to be busy this year !

 

[jamayfie]

I think C18 may be backwards.

I didn’t give sufficient detail before @Shertzy: I think C18 should have its negative pole facing C14

 

[Shertzy]

I didn’t give sufficient detail before @Shertzy: I think C18 should have its negative pole facing C14

Hi @jamayfie , thanks for the heads up, on the V4 board its inverted, I tracked down issues with D3,D4, R1 and Q2, parts ordered, I think I will find some more issues on the other end of the board but everything I can competently test (might be over estimating myself here) seems in order. Cross that bridge when I get there once the power stage is all good.
Have a nice day all

 

[jamayfie]

@Shertzy whoops, I saw the 2023 date stamp and thought you had the v3 board. You’re right!

 

[SkyPirate]

Congrats and enjoy. I concur.

Pearl 3—>Iron Pre—>M2X (Ishikawa 1st; 8 boards left to try) sounds awfully good out of LX-Mini or Zu DW speakers. Unfortunately, or is that fortunately, i can’t stop either. Looking at building speakers and open to suggestions….

I spent the last 8-9 months working on these.. Incredible.. Can't recommend enough if you have the room for them!

 

[roclone]

I'm building a Balanced Iron Pre. Am I correct in thinking that you could use a power traffo with 2 x 18v secondaries or a centre tapped 18-0-18v one as the circuit is using +18v & -18v?

Any opinions about O-Type donuts which seem popular in high end audio kit ATM?

TIA

 

[ItsAllInMyHead]

I'm building a Balanced Iron Pre. Am I correct in thinking that you could use a power traffo with 2 x 18v secondaries or a centre tapped 18-0-18v one as the circuit is using +18v & -18v?

Yes, correct. Straight from schematic.

Any opinions about O-Type donuts which seem popular in high end audio kit ATM?

Not familiar with "O-Type". Others may weigh in.

 

[Zen Mod]

All Donuts are O

 

[roclone]

Thanks for the answer - this is the type of donut I meant, it's not a torroid:

 

[SteveVulture]

Any opinions about O-Type donuts which seem popular in high end audio kit ATM?

As you're in the UK, I buy from Tiger Toroids in Norfolk. I buy small 80VA toroidal transformers to make power supplies, mine are exactly as per the Iron pre build suggestion. I buy 80VA with a foil screen between primary and secondary (which is connected via a flying lead to mains earth) and a GOSS band around the outside. I then pot them myself. You just need an 18-0-18 version of that. Or two of them, or two 40VA 18-0-18. But Stephen at Tiger will help. They make transformers for at least one well known UK hifi brand.

 

[Zen Mod]

20VA is plenty enough for Iron Pre SE

10VA is plenty enough for one channel of Iron Pre Bal

 

[Spikee]

Another Balanced IronPre is born 😃
Thanks Zen Mod and IAimH for making it possible and for the help along the way. Super fun build, no issues on power up, biases set without issues, and it‘s playing beautifully now! 😁

 

[Zen Mod]

 

[SteveVulture]

That looks really good !

 

[SteveVulture]

What is benefit of 24v relays over 12V ? I'm about to order 12V, have none in stock, is it better to order 24V ?