[Pricklely Peete]

You'd have to relocate the board back about 1 or 2 cm but that would mean getting a different headphone jack and rewire it to the now relocated H/Amp pcb....not to mention drilling and tapping the new mounting holes into the chassis bottom plate for the pcb standoffs. The pin on the front of the 50K AX2 has to be cut off in order to mount flush on the back side of the Zero's face plate.

All this is far more trouble than it's worth IMO.

Better just to get the NOS pot from Lawrence.

Then again if anyone wants to try it I say go for it.....

My suggested install method is just that a suggestion.


Peete.

 

[StratCat]

Quote:

Originally Posted by MadMan007 /img/forum/go_quote.gif Could be, we'd need someone to inspect it closely or have a ciruit diagram to know. I was basing the statement that it uses the headphone amp as a preamp for RCA out when the light is on upon user's statements that using the unit as a preamp versus a pure line-level DAC changes the sound signature.

Speaking of which:

Does anyone know if the 4 large black upright heat-sinked devices on the HPA board, to which refer to as "Vregs", are actually voltage regulators?

I ran the P/N thru Google and it came back as a "Bi-Polar General Purpose Transistor". I realize transistors can be used as Vregs, but now am thinking they actually might be configed as audio output transistors, which is why when we replace the HPA op-amps with op-amps of widely varying output power and current ratings the HPA volume stays roughly the same. This lack-of-change isn't what I would expect to see if the HPA ouput was run directly off the op-amps.

Well, just some thoughts, anyway.

 

[bundee1]

with regards to Lawrence's alps pots, maybe they're clones? Not to cast aspersions on him because he could be buying them unknowingly but if you search for that pot on eBay you come up with clones. I have also seen large electronics suppliers selling the real one only in bulk. I don't care as long as it's an improvement over the stock pot. I ordered one from lawrence.

 

[Pricklely Peete]

Quote:

Originally Posted by StratCat /img/forum/go_quote.gif Speaking of which: Does anyone know if the 4 large black upright heat-sinked devices on the HPA board, to which refer to as "Vregs", are actually voltage regulators? I ran the P/N thru Google and it came back as a "Bi-Polar General Purpose Transistor". I realize transistors can be used as Vregs, but now am thinking they actually might be configed as audio output transistors, which is why when we replace the HPA op-amps with op-amps of widely varying output power and current ratings the HPA volume stays roughly the same. This lack-of-change isn't what I would expect to see if the HPA ouput was run directly off the op-amps. Well, just some thoughts, anyway.

A simple check with a DMM confirms they are regulating the +15 -15 VDC lines.

The gain device is the opamps in the H/Amp section.

I'm trying to track down some modern regs with better specs to replace the old Toshiba's ...I feel some more performance can be gained from the H/Amp section by doing so....although it's just a guess at this point...at least it's a cheap upgrade.

Peete.

 

[StratCat]

Quote:

Originally Posted by Pricklely Peete /img/forum/go_quote.gif A simple check with a DMM confirms they are regulating the +15 -15 VDC lines. The gain device is the opamps in the H/Amp section. I'm trying to track down some modern regs with better specs to replace the old Toshiba's ...I feel some more performance can be gained from the H/Amp section by doing so....although it's just a guess at this point...at least it's a cheap upgrade. Peete.

Very good Peete!

Yeah, I've come to like the Zero's HPA with the LT1364's, and would love to improve it, as well. Driving K701's from an internal HPA is no easy task, tho. I guess I'll add those hi-current op-amps back to my list of things-to-get and add them back into the "upgrade" line of my sig.

I wish we had a schematic of this thing. It might be possible to play with the resistors and pot to increase gain. If the op-amp's in inverting mode and the pot's in the feedback loop, simply getting a larger pot would increase gain. No idea what that does to SQ tho. I'm not familiar with audio applications.

Thanks for checking the Vreg thing out.

 

[Pricklely Peete]

StratCat,

Have you seen my PS1 mod for the H/Amp in the Zero MOD thread ? It's still a work in progress but the Zero's H/Amp has certainly got some balls now over the stock setup.

The stock regs are holding it back IMO in current delivery I'm almost positive of that...once the regs are uprated to to deliver 1A each (I think the stock regs are limited to .5 amp) the story may change considerably for cans of all stripe. Just a hunch at this point....I'll go with LM ot LT low drop out low noise types. I just need to find a vendor for these amongst other parts I need for the moment.The idea is to run 2 HDAMs in it rather than IC opamps.

I also have a chassis coming from China (slow boat that should be here some time in late Nov or early Dec).....I can complete the FrankenZERO SST at that time

Peete

 

[sennsay]

Quote:

Originally Posted by StratCat /img/forum/go_quote.gif Very good Peete! Yeah, I've come to like the Zero's HPA with the LT1364's, and would love to improve it, as well. Driving K701's from an internal HPA is no easy task, tho. I guess I'll add those hi-current op-amps back to my list of things-to-get and add them back into the "upgrade" line of my sig. I wish we had a schematic of this thing. It might be possible to play with the resistors and pot to increase gain. If the op-amp's in inverting mode and the pot's in the feedback loop, simply getting a larger pot would increase gain. No idea what that does to SQ tho. I'm not familiar with audio applications. Thanks for checking the Vreg thing out.

Hi guys, I think you will find that those four trannies on heatsinks are the output transistors. The power supply for the head amp comes from the two regulators on the main board that get so hot. If you unplug the black (3 together) cable from the head amp board that comes from the PS, you will find no power to the amp at all. It is quite common to use power transistors for power supplies and vice versa. KHA has a similar set up, if not identical.
The ubiquitous 3055 power transistor is often used as a high power regulator.
The op-amps alone don't use anything like the amount of power to make those four trannies so warm if they were regulators. If you pull the black power cable from the amp board you will find the regulators on the main board go almost cold, no load on them.
Also, my old 600 ohm Senn 540 Reference cans require far too much power to be able be driven by op-amps alone and I could get plenty of gas out of the Zero's amp when I used them.

Well, that's my theory for the day, but I shall pull the amp board later and have a look at the circuit in more detail.

S-Man

 

[| Scorpio |]

Sorry to keep on coming into this thread with noobish questions, but I'm just about to pull the trigger on my Zero. I know that Lawrence is the only one who offers the volume pot upgrade, but is it really a substantial difference over the default one? It would seem to be so much more convenient to buy from this selller, who includes the USB to Optical converter and an upgraded opamp. I don't want to regret getting the less upgraded version in the future, though, so maybe I should go with Lawrence... Bah, I don't know what to do. Help?

 

[StratCat]

Quote:

Originally Posted by Pricklely Peete /img/forum/go_quote.gif StratCat, Have you seen my PS1 mod for the H/Amp in the Zero MOD thread ? It's still a work in progress but the Zero's H/Amp has certainly got some balls now over the stock setup. The stock regs are holding it back IMO in current delivery I'm almost positive of that...once the regs are uprated to to deliver 1A each (I think the stock regs are limited to .5 amp) the story may change considerably for cans of all stripe. Just a hunch at this point....I'll go with LM ot LT low drop out low noise types. I just need to find a vendor for these amongst other parts I need for the moment.The idea is to run 2 HDAMs in it rather than IC opamps. I also have a chassis coming from China (slow boat that should be here some time in late Nov or early Dec).....I can complete the FrankenZERO SST at that time Peete

Hi Peete -

Yeah, I saw it last week. I replied to a post in one of the DIY threads earlier today. I'm constantly torn between deciding in which thread to post, since this one seems to have a continous life of it's own!

I think in an ideal world, this thread would stop at anything much more than op-amp/HDAM rolling, seller upgrade options, or simple non-mod cosmetic replacement (vol pot knobs)?

Unfortunately, it doesn't work that way, IRL, eh?

I hate to see the DIY threads languish.

Oh...back ontopic: No Newark affiliate north of the 49th Parrallel?

 

[StratCat]

Quote:

Originally Posted by sennsay /img/forum/go_quote.gif Hi guys, I think you will find that those four trannies on heatsinks are the output transistors. The power supply for the head amp comes from the two regulators on the main board that get so hot. If you unplug the black (3 together) cable from the head amp board that comes from the PS, you will find no power to the amp at all. It is quite common to use power transistors for power supplies and vice versa. KHA has a similar set up, if not identical. The ubiquitous 3055 power transistor is often used as a high power regulator. The op-amps alone don't use anything like the amount of power to make those four trannies so warm if they were regulators. If you pull the black power cable from the amp board you will find the regulators on the main board go almost cold, no load on them. Also, my old 600 ohm Senn 540 Reference cans require far too much power to be able be driven by op-amps alone and I could get plenty of gas out of the Zero's amp when I used them. Well, that's my theory for the day, but I shall pull the amp board later and have a look at the circuit in more detail. S-Man

OK -

That does it!

The ideas are coming fast and furious.

I'll try to make some time to do the Vpot upgrade ASAP, but it will be Tuesday/Wednesday at the earliest, when I'll pop the HPA board out and try to do some basic sig tracing too, to see what I can add to the confusion.

Just for the record: Do we want to continue this discussion here, or should we try to give some life to the DIY threads?

 

[Pricklely Peete]

Quote:

Originally Posted by sennsay /img/forum/go_quote.gif Hi guys, I think you will find that those four trannies on heatsinks are the output transistors. The power supply for the head amp comes from the two regulators on the main board that get so hot. If you unplug the black (3 together) cable from the head amp board that comes from the PS, you will find no power to the amp at all. It is quite common to use power transistors for power supplies and vice versa. KHA has a similar set up, if not identical. The ubiquitous 3055 power transistor is often used as a high power regulator. The op-amps alone don't use anything like the amount of power to make those four trannies so warm if they were regulators. If you pull the black power cable from the amp board you will find the regulators on the main board go almost cold, no load on them. Also, my old 600 ohm Senn 540 Reference cans require far too much power to be able be driven by op-amps alone and I could get plenty of gas out of the Zero's amp when I used them. Well, that's my theory for the day, but I shall pull the amp board later and have a look at the circuit in more detail. S-Man

Thanks S-Man.......hmmm so upgrading these to better higher rated units in conjunction with the PS1 mod should be the ticket for driving a can like the K701 with what it wants...more current ......

Interesting...worth a shot...now all I need is K701's and 4 parts

Peete.

 

[StratCat]

Quote:

Originally Posted by Pricklely Peete /img/forum/go_quote.gif Thanks S-Man.......hmmm so upgrading these to better higher rated units in conjunction with the PS1 mod should be the ticket for driving a can like the K701 with what it wants...more current ...... Interesting...worth a shot...now all I need is K701's and 4 parts Peete.

There's something disheartening about knowing your fav cans in your fleet have a rep being the standard bearer for stressing the current capability of HPA's...

 

[Pricklely Peete]

I vote for the MOD thread but I'm biased

Peete.

 

[bundee1]

I think anything with the risk of electric shock or burning should be in the mod thread.

This thread should be about sound reviews, simple plug and play mods, and vendor reliability issues.

 

[Pricklely Peete]

Sounds good to me bundee1 !!!

Peete.