Infinity IRS Beta Mods Query

[msb64]

Hi Paolo

I asked about schematics for the Lite 60 DAC unit, but had no luck.
Pacific Valve states that as part of the agreement they have with their suppliers, they cannot release the schematics.
The units appear to be layed out internally with plenty of room to make modifications fairly straight forward.
I can't wait to get mine and try it out.

I didn't realize that the input impedance of the Thresholds were as high as 75K. I checked with the Hafler manuals, and they state the stock DH200s are 22K and the stock DH220s are 47K.

Because of the great results I have had with my 80s Pooge modified DH200, the plan so far is to build 4 Hafler monoblocks.
I will use Musical Concepts boards in a pair of DH200s for the mid/high towers, and a pair of modified DH220s for the bass towers.
It will be nice to get working on them, when all of the parts finally get here.

The bypass on the servo box for the mid/high towers is just that, no additional electronics are involved, basically just a splitter. The same thing can be done by branching off the outputs right from the source (or the preamp as per Infinity Beta manual).

[inertial]

Thanks Mike.
These people make me "furious"
If I purchase a electrodomestic I have legal right to have the wiring schematic ( in europe)!
They are anacronistic and near "out of the law" IMO!!
In my country we says " the Pulcinella secret "
I hope some nice DIY guy look the internal of the DAC60 and can post the schematic in all the forums !
It is sure a very elementar PSU ( for sure a mediocrity PSU) who can seriously degradate the sound quality.
Do we are asking too much? I do not believe .
The digital part:
Very simple also. De-emphasis are OFF ( very bad thing)
There is not a switch for absolute polarity. ( even worse!)
There is not a switch for swap the digital filter from brickwall to slow rolloff. ( bad again)


About 47Kohm for the DH220 it is still workable IMO.
Maybe with a pot of only 10-15Kohm.
I have nothing Vs Hafler but remain of my idea for TUBES Those emit-emim are like razors !!
Have goods experimentations and listening sessions Mike !

Cheers,
Paolo

[msb64]

Hi Paolo

I received my modified DAC last friday, and it is a nice looking piece.
It is also a decent sounding unit, even with the stock Sovtek tubes.
I never got to try the Philips tubes because I only received one of them, the other box had another Sovtek tube in it. They are sending me out a replacement for it.

The bass is very nice, solid, quick and low reaching. The mids are much warmer and more forward, but the highs are a little subdued, at least for my liking. I installed a couple of Vishay MKP .01ufd bypass caps on the Jantzen 4.7ufd caps and it helped quite a bit. I will probably install something better to replace the Jantzens though.

It is hard to judge exactly what has been modded in this unit, because I don't have a stock unit to compare it to. My best guess is mainly component substitutions as there doesn't appear to be any wiring or board changes. Besides the Jantzen caps, there are other polypropylenes and many of the electrolytics (if not all) are Elna caps. Plenty of space inside the unit too, makes mods much easier.

It would be nice to get a hold of a stock unit, and upgrade the various components with my own choices. A schematic would have been handy to help pinpoint key signal path components, and probably would have helped for design mod considerations as well.

I took a bunch of images of both sides of the board, if you would like to see them, I can send them to you. They are high enough quality that you can zoom in on them.

I took apart my Pooge modified Hafler amp, to start the whole monoblock conversion process.
I definitely need to spend a few $ on some large PS caps now, and maybe even some larger toroidal transformers later on.

Mike

[inertial]

Hi Mike,

man, we are clamourosly OT here!

Maybe you could be open a thread in the digital (?) or tubes ( better)
section.
I think you can post photo and ask if someone kind guy know the schematic

About the "soft" highs I think it is normal, you come from crappy ICs !
IMO keep the Sowtek, they are famous to be "open" on the highs and are not microphonics too

If you do not like the "soft" try to open slightly the EMIT-SEMIT control.....

Moreover, excuse me If I am repetitive, try to jump the preamplifier!

About the mods I think you are correct. Parts soubstitutions, not circuit modifications I believe.
If you want big modds you have to look the "Brigatta".
But I am sure a complete PSU redesign could will be miracles, here.
To not talk about the SRPP......I do not like that

Cheers,
Paolo

[msb64]

I finally got around to ordering caps for the crossovers.
Ended up ordering Solen MKP PA series caps to replace all the oem NP electrolytics.
As you can see in the pictures, the biggest ones were huge, about the size of a tomato juice can.
The replaced caps were 300 mfd, 150 mfd, 36 mfd and 20 mfd.
Fortunately the mid/high tower bases had enough room to install the upgrade caps.
The change was immediately noticable and surprisingly significant.
The already "open" and "revealing" betas became even more open, it was like a blanket had been covering the speakers and was suddenly removed.

According to some sources, the sound/peformance should improve with time, it will be interesting to see if this actually pans out.
If it does improve, that would be a definite plus, but it is already a good return on invested time and funds as it is.
I can definitely recommend this mod, a substantial improvement for only about $318 Cdn (includes shipping cost) worth of parts.

This is even with a ss Threshold preamp, I have yet to try my Musical Design SP2B tube preamp, which has a nice Direct input feature.
I am also using a Lite 60 DAC modified unit from Pacific Valve, that I have also made some bypass cap changes to myself according to recommendations made by Tony Gee on his humblehomemadehifi.com website, well worth checking out.

I can also confirm that the Vishay Mkp1837 .01 mfd Mkp caps are real performers, after having tried them on various tube and solid state preamps as well as several solid state amps.
I ended ordering 60 of them from Allied Electronics (MKP1837-310-011) for only $1.47 US each plus shipping

As per Inertials recommendations, I am looking into replacing the 3 oem iron core inductors with Solen litz air core inductors. Price works out to be only around $200 Cdn, it is just a matter of determining if the upgrade components can be properly installed and secured in the available space.