[Sathimas]

@ macm75 & boilermakerfan

thanks for the advice - I just sent an email to top-print how big the transformer actually is.
If a was able to sell the "wrong" transformer ordering a new one would be cheaper.

Anyway I'm lucky to hear that I could still use the transformer.
The mistake was on my side by the way.

Thank you also for the tip with the aikiko preamp - but if I can only use
it with my speaker setup its not useful for me since my headphone- and
speaker- setup are combined - only one CDP and turntable.

 

[marcus1]

I've almost got all the components to start assembly on my tube hybrid and have after rechecking the components (I have received) I find I've ordered the wrong resistors

.
For the power supply resistors at R17, R18, R20 and R21, instead of 249K, 1/2 watt resistors, I've ordered 249K, 1/4 watt resistors (from the datasheet, these have a maximum working voltage V≅ ≤ 200 - http://www.vishay.com/docs/31018/cmfind.pdf).
Are these 1/4 watters OK to use instead of the recommended 1/2 watt?

I've also been reading about volume controls but am thinking about using my AKSA GK-1 preamp as opposed to something like the kit-set 24 step ladder type going cheap on ebay (VOLUME CONTROL TO 12AX7 6SN7 ECC88 ECC82 ECC81 EL34 6V6 - eBay (item 320456036248 end time Jan-29-10 04:58:14 PST), as discussed earlier.
Will the eXStata be a good match for my preamp or are there be gain issues to think about?

Thanks

 

[paxeaxe23]

Just been trying to work out the best way to have Balanced and unbalanced inputs. Would a combi Jack/XLR Female connector work? I can't find any pin diagrams for these sort of connectors.

 

[orkney]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif I wouldn't recommend it to a beginner. It isn't difficult per se, but there are a LOT of potential gotchas from the shunt power supply, high voltages, matching JFETs, etc. An EE friend isn't going to help with these key construction issues, unless they build it for you. Start with something simpler, and work your way up.

Thanks for the advice -- I'll start with a simpler build and keep this one in mind. Better my kids should have their fadda, as they say.

best,

o

 

[Emooze]

boilermaker, pabbi, did you end up putting any holes in the nabu case for ventilation or is the space inside good enough?

 

[cyanoacry]

Hi all,

Figured out my issue: if the input JFETs aren't matched, then the trim pots won't be able to get the offset down to zero. Turns out I probably mismeasured or miswrote the Idss when I was testing all of them, so I matched another quad and went for it.

On another note, it took me 60 JFETs to get three good quads. The first batch of 30 that I ordered had one half of a quad---nearly all the JFETs had Idss < 10mA.

Anyway, the amp's working now; I'm waiting for it to warm up so I can adjust the offset. (Currently =<+/-1V)

Thanks,
cyanoacry

 

[BoilermakerFan]

Quote:

Originally Posted by Sathimas /img/forum/go_quote.gif @ macm75 & boilermakerfan thanks for the advice - I just sent an email to top-print how big the transformer actually is. If a was able to sell the "wrong" transformer ordering a new one would be cheaper. Anyway I'm lucky to hear that I could still use the transformer. The mistake was on my side by the way. Thank you also for the tip with the aikiko preamp - but if I can only use it with my speaker setup its not useful for me since my headphone- and speaker- setup are combined - only one CDP and turntable.

Not a big deal actually, just use a selector switch for balanced or 4PDT switch for SE inputs... Send the signal straight through to eXStata, or send the signal to the Aikido to the speaker amp... The volume potentiometer can be in the circuit before the switch so you have one volume control for both options.


Quote:

Originally Posted by Emooze /img/forum/go_quote.gif boilermaker, pabbi, did you end up putting any holes in the nabu case for ventilation or is the space inside good enough?

A lot of ventilation... Over the amp boards, nice big cut outs in artistic shapes on the top. You'll have to wait to see the results. The PS section will be perforated with small holes to vent heat above the heatsinks. The bottom chassis will be perforated under the board at the heatsink areas too, to allow cool air in. I'll probably add additional vents on the bottom in other areas too. Screen will put over all the openings.

 

[pabbi1]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Yeah, like that is going to stop the diehards......

Exactly - I have some black plate CBS in the production build, and Tungsol in the proto - but, since they aren't the same to begin with, no real observation there. But, I also have some Amperex, and bought the Telefunkens off eBay - I just had to.

Ok, so what did I hear? The actual participants were the two hybrid eXStatA, a Stax 313, Stax SRM T1, and the Headamp KGBH. Since we did NOT use the same source, there is no ceteris paribus, but...

I remembered within 30 seconds why I long ago sold the SRM-T1 - simply not enough power. Oh they do well for the first half of knob travel, you know, ok, but lose steam after 12 o'clock. same with the 313 - servieable, but leaving you really wanting more.

Caveat: I just don't like the OII, and listened to unmodded and modded versions today - just not for me.

So, using the HE60, I compared the 5 amps. The BHSE is a REALLY nice amp. Radiohead's 'Subterranean Homesick Alien' was as etherial as anything I have ever heard, from the midrange up. Just transported me to a different place - almost astral projection.

The eXStatA (prod), on the same material is just a tad less lush, but far tighter in the nether regions - a firm bottom, with no jiggle. The midrange is just as lush, but not *quite* the same air, though a crisper presentation.

Same experience with the Tool test - here we used Aenima, where the result was more of the same. The two amps are comparable, and really are tradeoff for what is more important to the listener.

I do NOT know what the tubes are in the KGBH SE, but the bass was a bit flabby, an experience I live with on BH (even with Mullard xf2, circa 1961), well, or did (it is now dead to me, even if it lives).

Also tried the 404LE on my prod version, and like them a lot, but there is a bit of what I'll call etch - something up around (WAG) 15k or so that is just a tad harsh - not sure what it is, but, enough to keep me from getting a pair (though several other factors intersect with that decision as well). This was on eXStatA and the BHSE

Net-net, you guys are building a really good amp. Really.

 

[BoilermakerFan]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif Exactly - I have some black plate CBS in the production build, and Tungsol in the proto - but, since they aren't the same to begin with, no real observation there. But, I also have some Amperex, and bought the Telefunkens off eBay - I just had to. Ok, so what did I hear? The actual participants were the two hybrid eXStatA, a Stax 313, Stax SRM T1, and the Headamp KGBH. Since we did NOT use the same source, there is no ceteris paribus, but... I remembered within 30 seconds why I long ago sold the SRM-T1 - simply not enough power. Oh they do well for the first half of knob travel, you know, ok, but lose steam after 12 o'clock. same with the 313 - servieable, but leaving you really wanting more. Caveat: I just don't like the OII, and listened to unmodded and modded versions today - just not for me. So, using the HE60, I compared the 5 amps. The BHSE is a REALLY nice amp. Radiohead's 'Subterranean Homesick Alien' was as etherial as anything I have ever heard, from the midrange up. Just transported me to a different place - almost astral projection. The eXStatA (prod), on the same material is just a tad less lush, but far tighter in the nether regions - a firm bottom, with no jiggle. The midrange is just as lush, but not *quite* the same air, though a crisper presentation. Same experience with the Tool test - here we used Aenima, where the result was more of the same. The two amps are comparable, and really are tradeoff for what is more important to the listener. I do NOT know what the tubes are in the KGBH SE, but the bass was a bit flabby, an experience I live with on BH (even with Mullard xf2, circa 1961), well, or did (it is now dead to me, even if it lives). Also tried the 404LE on my prod version, and like them a lot, but there is a bit of what I'll call etch - something up around (WAG) 15k or so that is just a tad harsh - not sure what it is, but, enough to keep me from getting a pair (though several other factors intersect with that decision as well). This was on eXStatA and the BHSE Net-net, you guys are building a really good amp. Really.

Thanks Al, really glad to hear that because, for me... Bass FTW!

 

[gilency]

Pabbi, what is the ppv on the proto SS you sold me? Enjoying it a lot with my Sigma Pro!

 

[pabbi1]

I am guessing 900v, but AC will have to verify, as we also did a follower mod to squeeze out some extra Vpp.

 

[sergery]

Quote:

Originally Posted by marcus1 /img/forum/go_quote.gif Are these 1/4 watters OK to use instead of the recommended 1/2 watt?

not sure

Quote:

Originally Posted by marcus1 /img/forum/go_quote.gif I've also been reading about volume controls but am thinking about using my AKSA GK-1 preamp as opposed to something like the kit-set 24 step ladder type going cheap on ebay (VOLUME CONTROL TO 12AX7 6SN7 ECC88 ECC82 ECC81 EL34 6V6 - eBay (item 320456036248 end time Jan-29-10 04:58:14 PST), as discussed earlier. Will the eXStata be a good match for my preamp or are there be gain issues to think about? Thanks

that would work. I found 50k is fine, maybe even overkill. If you want to save yourself assembly you could get something like this, I got the balanced version.

Quote:

Originally Posted by paxeaxe23 /img/forum/go_quote.gif Just been trying to work out the best way to have Balanced and unbalanced inputs. Would a combi Jack/XLR Female connector work? I can't find any pin diagrams for these sort of connectors.

There is a diagram on the website for wiring a switch, I think that is the preferred method. I plan to implement it. I suppose a combo jack would work though. personally I would rather have signal paths that are either in use or out of the way so I can leave multiple sources plugged in.

Quote:

Originally Posted by gilency /img/forum/go_quote.gif Pabbi, what is the ppv on the proto SS you sold me? Enjoying it a lot with my Sigma Pro!

Should be pretty close to 1kV p-p, I think it was follower modded. I can tell you it is no less loud/dynamic than my beta.

 

[Hopstretch]

Looking forward to giving the Exstata a shot with the O2s. Their midrange is sweet with the 007t but the lower end is notably floppy.

 

[TimJo]

Quote:

Originally Posted by macm75 /img/forum/go_quote.gif Yes, Please do and report back!!

Well, I am running the black plates now, and I can't say there is an obvious difference. There's part of me that thinks there may be a slight improvement in the low end (if that's even possible?), but I'm also thinking that my headphones are just breaking in and improving with every album I play. Bottom line is that it is sounding amazing. I haven't listened to my Beyers for weeks now.

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif So, using the HE60, I compared the 5 amps. The BHSE is a REALLY nice amp. Radiohead's 'Subterranean Homesick Alien' was as etherial as anything I have ever heard, from the midrange up. Just transported me to a different place - almost astral projection. The eXStatA (prod), on the same material is just a tad less lush, but far tighter in the nether regions - a firm bottom, with no jiggle. The midrange is just as lush, but not *quite* the same air, though a crisper presentation. Same experience with the Tool test - here we used Aenima, where the result was more of the same. The two amps are comparable, and really are tradeoff for what is more important to the listener. I do NOT know what the tubes are in the KGBH SE, but the bass was a bit flabby, an experience I live with on BH (even with Mullard xf2, circa 1961), well, or did (it is now dead to me, even if it lives). Also tried the 404LE on my prod version, and like them a lot, but there is a bit of what I'll call etch - something up around (WAG) 15k or so that is just a tad harsh - not sure what it is, but, enough to keep me from getting a pair (though several other factors intersect with that decision as well). This was on eXStatA and the BHSE Net-net, you guys are building a really good amp. Really.

I'm beginning to realize what a great amp this really is, and a fun build at that. I can't wait to get the enclosure finished.

Interesting to hear about the flabby bass on the KGBH - I'm glad I have an eXStatA because I do prefer 'a firm bottom, with no jiggle.'

I keep reading about the etch that folks talk about on the 404LE's, but I guess I'm not hearing this. I need to get to a meet and do some side by side comparisons...

So Al, how do the HE60's compare to the 404LE's in terms of bass response?

 

[pabbi1]

Quote:

Originally Posted by TimJo /img/forum/go_quote.gif WellInteresting to hear about the flabby bass on the KGBH - I'm glad I have an eXStatA because I do prefer 'a firm bottom, with no jiggle.' I keep reading about the etch that folks talk about on the 404LE's, but I guess I'm not hearing this. I need to get to a meet and do some side by side comparisons... So Al, how do the HE60's compare to the 404LE's in terms of bass response?

That is one reason I settled on the he60 - I think it has better bass than the Stax - you will get virulent disagreement amongst the Mafia, who will fight to the death claiming the OII has better bass, but the issue is in how one defines bass. As a bass player (as it were), I listen to the QUALITY of the notes, moreso than QUANTITY, which the he60 has more of both over the 404LE, and the debate is left up to the reader about he60 vs OII, ESPECIALLY on the eXStatA.

You will NOT be left for wanting bass on eXStatA, regardless of phones, though it is NOT a mushy below the bottom mess rattling your earpads, and, not for everyone - like guys bouncing their cars with megawatt subwoofers.

My bias, my rig, my preference and all that. I do think the jury is out on eXStatA and the OII. Marc listened a bit, as did ASR, with their respective OII. Maybe they will post in the DFW meet impressions.