Thanks all. I’ll add some solder to the suggested points tomorrow.
Yes, I have a solder sucker and have watched several how to videos. It always leaves just a enough solder in the hole that part removal remains a very high stress operation.. Especially any part with three legs. Maybe I need to buy a different one.
Thanks for the punkydawgs link. eBay shipping costs to AU appear to assume we live on a different planet..
Any alternative suppliers?
Yes, I have a solder sucker and have watched several how to videos. It always leaves just a enough solder in the hole that part removal remains a very high stress operation.. Especially any part with three legs. Maybe I need to buy a different one.
Thanks for the punkydawgs link. eBay shipping costs to AU appear to assume we live on a different planet..
Any alternative suppliers?
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^^The member here on diyAudio, "NicMac".
Jumpers are properly done.
I'm 95% convinced you have a bad solder connection somewhere, Extremeboky's suggestion of the -IN to GND jumper is a good one.
Put it back together and turn it on with your meters hooked up and poke/bend the board a little in various places and when touching components and see if the offset jumps as the connection is made. This is a fairly common issue.
Jumpers are properly done.
I'm 95% convinced you have a bad solder connection somewhere, Extremeboky's suggestion of the -IN to GND jumper is a good one.
Put it back together and turn it on with your meters hooked up and poke/bend the board a little in various places and when touching components and see if the offset jumps as the connection is made. This is a fairly common issue.
I am getting ready to build a new chassis/PSU combo and update the existing chassis for dual mono. I have a question re: overall versatility. My goal is to have two essentially identical chassis. I'd like to swap boards in and out with the only soldering necessary being for the inputs. I have no rationale, but I'm OK with quick connects for the outputs and rails, but I'm not a fan for inputs...
I am learning a bit at a time re: balanced and differential signaling, but I admit I usually go by rote vs. having a full understanding (yet).
This is an Aleph J question, but it also ties to other FW amps.
The AJ boards are clearly set up for accepting a balanced / differential signal - even though I'm still not completely sure what in the topology lends itself to that.
The rest of the amp boards I currently have don't have a separate in- and gnd (F4, F5, SissySIT and M2x).
So, here's the silly question. If I sub out the RCA inputs for XLR inputs can I simply tie the In- to the ground for the other amps? I could then run the XLR outputs from my pre for all the amps without changing anything but adding a quick jumper between two pins when I wire up the inputs. It seems easier than drilling an additional set of holes and outfitting a switch etc. It will also make it much easier for me to blind A/B amps if I use the same cabling and output signaling from my pre. I'm particularly interested in making sure this will work for the F4 where I'd like to have the 20V signal from the pre from the XLR outputs.
Am I overthinking this... missing any key elements?
Thanks as always!
I am learning a bit at a time re: balanced and differential signaling, but I admit I usually go by rote vs. having a full understanding (yet).
This is an Aleph J question, but it also ties to other FW amps.
The AJ boards are clearly set up for accepting a balanced / differential signal - even though I'm still not completely sure what in the topology lends itself to that.
The rest of the amp boards I currently have don't have a separate in- and gnd (F4, F5, SissySIT and M2x).
So, here's the silly question. If I sub out the RCA inputs for XLR inputs can I simply tie the In- to the ground for the other amps? I could then run the XLR outputs from my pre for all the amps without changing anything but adding a quick jumper between two pins when I wire up the inputs. It seems easier than drilling an additional set of holes and outfitting a switch etc. It will also make it much easier for me to blind A/B amps if I use the same cabling and output signaling from my pre. I'm particularly interested in making sure this will work for the F4 where I'd like to have the 20V signal from the pre from the XLR outputs.
Am I overthinking this... missing any key elements?
Thanks as always!
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^ What you are proposing for the inputs sounds possible, although using just the 'hot' side of a balanced signal typically results in a loss of effective amplitude. If there is a way to make the output of your preamp single-ended when driving amplifiers that only use that type of input, then you're probably good to go.
hold your wild horses !
please differentiate:
1 what you need to do to convert amp's input from balanced (XLR) to unbalanced ( RCA) , vs.
2.what you need to do to get unbalanced (RCA) signal from preamp which is primary having balanced (XLR) output
in first case , usually all you need is to tie pins 1 and 3 ( practically grounding neg. input) and use RCA input /cables , if amp is equipped with them
in second case - majority of preamps is of that construction that you are using pin 2 as hot , pin 1 as GND , leaving pin 3 flappin' in da breeze
rare ones are demanding that pin 3 is also loaded , either being grounded or , in best case , with same Rload as pin 2
so , things are simple , as you see it
please differentiate:
1 what you need to do to convert amp's input from balanced (XLR) to unbalanced ( RCA) , vs.
2.what you need to do to get unbalanced (RCA) signal from preamp which is primary having balanced (XLR) output
in first case , usually all you need is to tie pins 1 and 3 ( practically grounding neg. input) and use RCA input /cables , if amp is equipped with them
in second case - majority of preamps is of that construction that you are using pin 2 as hot , pin 1 as GND , leaving pin 3 flappin' in da breeze
rare ones are demanding that pin 3 is also loaded , either being grounded or , in best case , with same Rload as pin 2
so , things are simple , as you see it
For simplicity, I built my Aleph J with XLR inputs only.
To avoid switches or other forms of hardware bolt on, I opted to get an RCA to XLR interconnect cable. I'm driving the Aleph with a balanced pre but I used an unbalanced pre with RCA outs for initial power up testing.
If you're AB testing from a single pre, you could run a cable connection as per my comment above. Level match with the other amp driven by a separate output and go from there. Get a friend to switch inputs if you want to do it blind.
To avoid switches or other forms of hardware bolt on, I opted to get an RCA to XLR interconnect cable. I'm driving the Aleph with a balanced pre but I used an unbalanced pre with RCA outs for initial power up testing.
If you're AB testing from a single pre, you could run a cable connection as per my comment above. Level match with the other amp driven by a separate output and go from there. Get a friend to switch inputs if you want to do it blind.
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Sorry to read this.
Unfortunately, you might just be at the wrong end of the statistical curve and what you've experienced is something like this:
The Bathtub Curve and Product Failure Behavior (Part 1 of 2)
Given the quality of your work that I've seen first hand, up close, I'd be surprised if you've done something knowingly daft.
From what I know, most reputable manufacturers of amps and other audio gear will "burn in" their gear by leaving it powered up for 24 hours or so to root out the runts that go down due to infant mortality. You might have copped a JFET runt ... spitballing though.
The pre-amp I'd use in this case has RCA outputs also, but my preference is to use the same cabling (even if mis-purposed a bit) and only have one set of XLR inputs on the back of the amp for ease of use for others. Telling my wife or friends to make sure to put pin jumpers in the AJ's XLR inputs when using RCAs or flip a switch would cause havoc, sadly. Plus... adding those inputs means that I have to drill holes. I am not a great metal worker, and if they weren't level, it would make me nuts
. If I just wire each respective amp internally to accept the XLR plugs - anyone can just pop over the plugs from amp to amp and move some speaker cables (until I get an A/B box built like Nelson's). I incorrectly assumed that by running all three wires to the input jack using a standard XLR connection (hot, cold, ground or In-, I+, Ground depending on who likes what words, and then tying the In- and ground together by running a jumper between pins 1 and 3 on the solder terminals "inside" the amp - that I would not lose effective amplitude. Rats. That was one of the benefits I was hoping to achieve: make it easier to level match and hold as many things as constant as possible from the source side. I get 20V max from the balanced outputs and 10V max from the RCA, so I thought I'd still get the 20V max. For the F4, apparently it needs a pre that can swing a lot of voltage and has a lot of gain (in my case 20dB), so I was hopeful. I learned something new. I'm not sure I understand it yet, but... that can come with more reading and maybe a little work with a DMM and/or scope.
Thank you as always!
hold your wild horses !
please differentiate:
1 what you need to do to convert amp's input from balanced (XLR) to unbalanced ( RCA) , vs.
2.what you need to do to get unbalanced (RCA) signal from preamp which is primary having balanced (XLR) output
in first case , usually all you need is to tie pins 1 and 3 ( practically grounding neg. input) and use RCA input /cables , if amp is equipped with them
in second case - majority of preamps is of that construction that you are using pin 2 as hot , pin 1 as GND , leaving pin 3 flappin' in da breeze
rare ones are demanding that pin 3 is also loaded , either being grounded or , in best case , with same Rload as pin 2
so , things are simple , as you see it
Horsies all reined in.
1. Converting amp input - agreed. That was my plan. Just solder a small jumper between pins 1 and 3 when I swap to boards that don't have a separate home for In- and GND. Then run Pin 2 to "In" and the Pin 1&3 combo to GND on the amp board. However, I was going to still use the XLR input cable.
2. I don't think I could leave pin 3 flapping. But I don't think it can hurt to tie pins 1 to 3 even if I could leave it flapping.
Things can't possibly be as simple as I see them.... that would be a first.
Thank you, ZM!
if you want to use 20db preamp with Aleph J, Zen Amount button would stay in area of low Zen
read What is Gain Structure?
read What is Gain Structure?
Love that article! Thank you. I learned a bit more and got a good few laughs re: Barry White and the ladies.
I knew the fundamentals, but I liked the very clear description re: music to noise ratio.I am using the 20dB solid state pre-amp as I type with the AJ. They sing gloriously together. B/C it also has an output impedance of only 1 Ohm, at some later date, I may learn more about removing the input buffers on some of the First Watt amps. I have a quote from Papa pasted somewhere that when used with preamps below 100 Ohm output impedance, no input buffer is needed. As nice as those Toshibas are... My guess is that the best buffer is no buffer. I still have too much to learn before I go down that road.
Oddly, my tube pre-amp also has a gain of 20dB, but will put out 60V Max. It does not specify the output impedance in the manual, and when I looked up how to measure it... I got lost. My guess is that it will be a lovely mate for the F4.
You are correct though that b/c of the gain - the pre-amp usually stays in the area of low Zen Amount (like on your pre-amps). The good news is that I have a 99 step relay attenuator with a crazy log scale on that pre amp. So, very quiet music but sounding still very pretty in the morning is 6 to 12 on the volume knob. 35 is comfortable and not making my wife upset - still have a nice conversation and coffee. 50 is rock and roll. 60 is LOUD. I never got to 99.
I am very curious to see how both pre-amps pair up with the F4. The SS gets along very well with the M2x and the AJ, but I'll try other pre-amps later. I am waiting on the other chassis to finish and try the SissySit, F4, and F5. The AJ and M2x are simply amazing.
I see Wayne's pre, a B-1, or a B-1 NuTube or a BA-3 FE or something fun in my future as I experiment and try to sate my appetite for learning and building. I'm just trying not to be too greedy
.
If anybody is thinking about bypassing the input buffer on an M2x power amp, pause for a minute and think very hard.
It seems so easy: just unbolt and remove the daughter card (red), then connect a shorting wire from input bolt to output bolt (blue). 10 wraps around the first bolt, 10 wraps around the second bolt, and Bob's yer uncle.
Don't forget resistor R1 (green). It's in series with your low-output-impedance preamp. Now you're driving the transformer from a source whose impedance is 1002 ohms. No es bueno.
_
It seems so easy: just unbolt and remove the daughter card (red), then connect a shorting wire from input bolt to output bolt (blue). 10 wraps around the first bolt, 10 wraps around the second bolt, and Bob's yer uncle.
However,
Don't forget resistor R1 (green). It's in series with your low-output-impedance preamp. Now you're driving the transformer from a source whose impedance is 1002 ohms. No es bueno.
_
Attachments
"Aleph style" heatsinks
Would anyone be interested in getting a bunch of "Aleph style" heatsinks as shown in the attachment?
I am considering to run a batch of these, and if there is enough interest, that might even be affordable. Just let me know either here or by PM. If there is enough interest, I might start a group buy thread for this.
Would anyone be interested in getting a bunch of "Aleph style" heatsinks as shown in the attachment?
I am considering to run a batch of these, and if there is enough interest, that might even be affordable. Just let me know either here or by PM. If there is enough interest, I might start a group buy thread for this.
Attachments
Mark, as always, thank you! I don't want to take the AJ thread too far off topic, but your post is greatly appreciated. I had read a bit about people building (I can't remember the word that was used, so my apologies) gimped F4s without input buffers. I also remember the discussion in the M2x thread. This got me curious. Since I have no idea what the output impedance of my tube pre-amp is, and measuring it seems far over my head for now, I'm leaving all buffers alone. It keeps things more versatile.
If at some point, I advance to knowing exactly what gear may be paired and understanding the complexities of the buffers and their removal, only then would I consider making any mods. Right now, I'm having fun mixing, matching, and learning.
The first advice of "Leave it alone if it works!" is still paramount.
Thank you for the thoughts. If it makes absolutely no difference to me, then I may just swap it back to RCA inputs and call it a day. That's certainly the easiest path. I've read at least one article that's stated or postulated that balanced with all its advantages, may not sound as good as a "normal" signal. I can't imagine why, but maybe some balanced gear is not set up well or has some disadvantages due to its added complexity and matching requirements. To me anyway... when I run the balanced (or preferably the CAST variant) outputs of my SS preamp to amps that are designed to utilize them - I really like the sound.
I know I'm going to find out for myself with the Aleph J
Again, thanks for the ideas and thoughts. I have a set of the RCA to XLR cables, so for pre-amps that are not balanced and/or don't have XLR outputs, I'm good.
Your problem sounds similiar to what I experienced.
Please see posts #3595 and #3647 and #3652.
My problem component was Q4, which you've already changed.
However, at Kevin Heems' suggestion I changed Q2, Q3, and Q4.
For no more than they cost, replacing Q2 and Q3 as well would seem worth trying.
Mega tester is inexpensive and quite useful. Check new components before they go in, old ones when they come out.
Good luck.
I almost gave up on my AJ, but was encouraged to hang in there and wound up with the best sounding amp I've ever had.