That is an unfortunate and expensive mistake. It involves the single most expensive part in your kit, and the one that is most hard to procure.
Please, consult with the local experts as to which grade of JFET is required (I suspect it's B grade, but could be wrong), and to what degree the ACA needs matching (if any). When ordering, go with an extensively proven source (of which there are two or three unfortunately).
I think your best bet would be to buy a set of 8 from the DIY store at this point, unless someone else suggests different.
Please be VERY mindful that there are dozens of providers of fake parts for this specific part out there so, if you think you have found a great deal on a single JFET that would solve your problems, it is probably too good to be true. It's not in vane that these are referred here sometimes as "unobtanium".
It's not that hard to find, but you need to go with a very safe source! Sorry to be the bearer of bad news.
Best regards,
Rafa.
Please, consult with the local experts as to which grade of JFET is required (I suspect it's B grade, but could be wrong), and to what degree the ACA needs matching (if any). When ordering, go with an extensively proven source (of which there are two or three unfortunately).
I think your best bet would be to buy a set of 8 from the DIY store at this point, unless someone else suggests different.
Please be VERY mindful that there are dozens of providers of fake parts for this specific part out there so, if you think you have found a great deal on a single JFET that would solve your problems, it is probably too good to be true. It's not in vane that these are referred here sometimes as "unobtanium".
It's not that hard to find, but you need to go with a very safe source! Sorry to be the bearer of bad news.
Best regards,
Rafa.
Not sure what is in the Anbes kit, but suspect it is a 'sucker'?
They can be a bit slow unless you cover the hole with the tip. Try working from the other side to the iron?
Failing that make some thin strips from matches or cocktail sticks and push the excess solder through towards the iron as you heat the pad. Yes you need three or four hands...
Shame you broke the LSK170 as Rafa said.
But it might be a good idea now to order 2 of them (B or C grade) and 2 new ZTX450. That way you start with good examples and do not have to worry if you have damaged the originals. Just a thought.
Okay, I see you are ahead of me. Good luck.
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Just finish my ACA v1.6 kit. Since I use it to power my Hifiman HE-6 headphone (which needs a speaker amp) via 4-pin XLR connector. I plan to swap out the 3-pin XLR at the back with a 4-pin one:
Neutrik NC4FD-L-1-BAG | Redco Audio
so I can directly connected to the amp without going though a XLR-speaker wire adaptor. My question is that if that 4-pin XLR adapter has pretty much the same diameter and mounting holes?
Neutrik NC4FD-L-1-BAG | Redco Audio
so I can directly connected to the amp without going though a XLR-speaker wire adaptor. My question is that if that 4-pin XLR adapter has pretty much the same diameter and mounting holes?
Yes much the same.
A look at the Neutrik site has the dimensions on the first download... NC4FD-L-1 | Neutrik
Alan
Thanks to the hint, Alan. I'll look it up.
After listening to it the whole day and compare to my humble Rotel RA-970BX at my office with Hifiman HE-6 headphone. It is clear that the mid/high freq of ACA seems to be softer with recessed (farther) stage comparing to Rotel. It is easier to listen but less definition on the music notes. I am curious if this is the sound signature the design?
After listening to it the whole day and compare to my humble Rotel RA-970BX at my office with Hifiman HE-6 headphone. It is clear that the mid/high freq of ACA seems to be softer with recessed (farther) stage comparing to Rotel. It is easier to listen but less definition on the music notes. I am curious if this is the sound signature the design?
Thanks for the reply, but I respectfully disagree. These headphones have much higher resolution to judge the details and tonal response (and my office is very quiet for high quality listening, 
). Not to mention that ACA cannot drive my low-efficiency speaker.
I am not talking about 3D instrument/voice location capability, which speaker may be better tool to evaluate, but just in general sense of presentation the notes are warmer, softer, weaker in volume, less sharper, and less impactful/edgy. I read some comments about its "less solid state" "more tube-like" sound. Note that my purpose is not to criticize or judge but to learn the sound signature of different design (or maybe my implementation error).
I could bring it back to compare with Aleph 3 at home, but still using HE-6 due to the above mentioned reason.
). Not to mention that ACA cannot drive my low-efficiency speaker. I am not talking about 3D instrument/voice location capability, which speaker may be better tool to evaluate, but just in general sense of presentation the notes are warmer, softer, weaker in volume, less sharper, and less impactful/edgy. I read some comments about its "less solid state" "more tube-like" sound. Note that my purpose is not to criticize or judge but to learn the sound signature of different design (or maybe my implementation error).
I could bring it back to compare with Aleph 3 at home, but still using HE-6 due to the above mentioned reason.
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No problems at all in disagreeing, the Rotel amps are renowned for good engineering at a very good price.
Your comment about comparing at home with the Aleph 3 which is no slouch when it comes to sound quality definition will be an interesting comparison. I assume you have added a headphone output to the ACA and Aleph 3.
Your comment about comparing at home with the Aleph 3 which is no slouch when it comes to sound quality definition will be an interesting comparison. I assume you have added a headphone output to the ACA and Aleph 3.
Considering how much I like my Aleph, I love the idea of ACA and hence the interest to know the difference. Certainly it would be boring if ACA = Aleph 3/5 = Aleph J = F6 ... etc. So knowing the difference and why you build it is important, right?
Since my only past tube amp is very un-tubey, this is my first time experience such sound, as I suspected, "tubey", and hence my previous question.
And yes, I do have a 4-pin XLR split to speaker posts. I actually fear to compare ACA to A3 since I know its extremely clear/transparent/crispy sound in my system.
So knowing the difference and why you build it is important, right?Since my only past tube amp is very un-tubey, this is my first time experience such sound, as I suspected, "tubey", and hence my previous question.
And yes, I do have a 4-pin XLR split to speaker posts. I actually fear to compare ACA to A3 since I know its extremely clear/transparent/crispy sound in my system.
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Hifiman HE-6 has input impedance of 50 ohm. I have not had issue with several amps that I tried.
ACA's soundstage with HE-6 is actually pretty spacious and well-defined. It is just that there is seem to be a "fine mesh" that block some of the sound wave and attenuated /smoothed out the high/mid frequency a little bit. And the high frequency is less sparkling and refined.
ACA's soundstage with HE-6 is actually pretty spacious and well-defined. It is just that there is seem to be a "fine mesh" that block some of the sound wave and attenuated /smoothed out the high/mid frequency a little bit. And the high frequency is less sparkling and refined.
Dujka, are you taking some steps at matching the volume output at the Headphones?
I ask because if one AMP has higher gain than the other, or other differences that may affect level, it gets really hard to evaluate the differences. That's why headphone evaluations go into painful efforts to match the volume levels.
If it helps, you are describing the sound I heard before adding a PRE in front of the ACA. When fed the line level 2V, I found exactly what you are describing. Once you put a PRE in front, it's a completely different story.
Hope this helps,
Rafa.
I ask because if one AMP has higher gain than the other, or other differences that may affect level, it gets really hard to evaluate the differences. That's why headphone evaluations go into painful efforts to match the volume levels.
If it helps, you are describing the sound I heard before adding a PRE in front of the ACA. When fed the line level 2V, I found exactly what you are describing. Once you put a PRE in front, it's a completely different story.
Hope this helps,
Rafa.
Thanks for the hint on level matching. This evening I used the pink noise, a SPL meter and a cardboard cutout to match the sound level when I compared HE-6 driven by Aleph 3 and ACA. It was a royal pain to use those tightly spaced speaker posts on Aleph 3.
The chain is Audio-GD Ref-7 (RCA output 2.5V) to Aleph 3 or ACA then to HE-6 connected to the speaker posts. The source is "Rush" soundtrack ripped into lossless FLAC using Exact Copy, played by Foobar2k through a 24-bit USB transport and coax to Ref-7.
Aleph 3 has 20dB gain vs. 14dB gain of ACA. I found that I need to use -32dB in Foobar2k with Aleph 3 and -22dB with ACA to match the sound level using pink noise.
Even after SPL matching, Aleph 3 easily wins my ears over. All of those guitar string plucking or drum beating were so real that it is really a joy to listen to. But I have to leave Aleph 3 at home. ACA after level matching showed some improvement. The high/mid is now more apparent and shows more clarity. However, it is still much less tangible and vague comparing to A3.
Even my DAC output is pretty hot at 2.5V, I still added a preamp in the chain for ACA per Rafa's suggestion. (I never like any pre-amp in the chain with A3, so I didn't use preamp with ACA in the first place). But the preamp does seem to do the magic for ACA. Now I'll say it is about 70% of A3's level in terms of the realistic feeling, although there is still some bass blooming.
It is interesting that my previous pursue of pre-amp for A3 was not fruitful at all, and yet ACA responded so well with a preamp.
The chain is Audio-GD Ref-7 (RCA output 2.5V) to Aleph 3 or ACA then to HE-6 connected to the speaker posts. The source is "Rush" soundtrack ripped into lossless FLAC using Exact Copy, played by Foobar2k through a 24-bit USB transport and coax to Ref-7.
Aleph 3 has 20dB gain vs. 14dB gain of ACA. I found that I need to use -32dB in Foobar2k with Aleph 3 and -22dB with ACA to match the sound level using pink noise.
Even after SPL matching, Aleph 3 easily wins my ears over. All of those guitar string plucking or drum beating were so real that it is really a joy to listen to. But I have to leave Aleph 3 at home. ACA after level matching showed some improvement. The high/mid is now more apparent and shows more clarity. However, it is still much less tangible and vague comparing to A3.
Even my DAC output is pretty hot at 2.5V, I still added a preamp in the chain for ACA per Rafa's suggestion. (I never like any pre-amp in the chain with A3, so I didn't use preamp with ACA in the first place). But the preamp does seem to do the magic for ACA. Now I'll say it is about 70% of A3's level in terms of the realistic feeling, although there is still some bass blooming.
It is interesting that my previous pursue of pre-amp for A3 was not fruitful at all, and yet ACA responded so well with a preamp.
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Several hours later, I was still kept awake listening to the death match of ACA and A3. It is really fun and eye opening to me and making me go over my CD collection. These two amps with the old newly discovered pre-amp really brought a concert hall to my study tonight with this classical piece:
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Agreed. This was my experience as well. When I tested the ACA I used my phone, a 3.55mm splitter and two cables to the inputs. It sounded OK. It was when I connected it to my preamp that I realized what I had. The ACA is an amazingly good amp. It sounds to me very much like a great tube amp.
board wiring possible fault?
Hi all, I've almost completed my second ACA power amp 1.6 in order to bridge two, but realised that I'd wired the "right" channel board to the left aux inputs and the "left" to the right aux inputs etc, everything else is the same, just as is on the guide, including the 39K resistor from the rear switch to the right aux input, and the cable from this switch to the left channel speaker neg post.
In other words, if I dismounted the two boards and moved them onto the opposite heatsinks it would look exactly as it does in the guides.
Just checking as I'm a bit dim with these things, that the above shouldn't be a problem right?
Hi all, I've almost completed my second ACA power amp 1.6 in order to bridge two, but realised that I'd wired the "right" channel board to the left aux inputs and the "left" to the right aux inputs etc, everything else is the same, just as is on the guide, including the 39K resistor from the rear switch to the right aux input, and the cable from this switch to the left channel speaker neg post.
In other words, if I dismounted the two boards and moved them onto the opposite heatsinks it would look exactly as it does in the guides.
Just checking as I'm a bit dim with these things, that the above shouldn't be a problem right?