Hi CJ,
any and all wire pairs that are a flow and return should be twisted as pairs.
This reduces, massively, the loop area of the aerial/receiver that each flow return loop creates.
It also reduces the effectiveness of the aerial/receiver function since alternate turns of the twist cancel the EMI radiated or received.
Once you have the layout finalised and the transformer rotated to find minimum (null) radiated field you can reduce the length of each twisted pair to the minimum.
any and all wire pairs that are a flow and return should be twisted as pairs.
This reduces, massively, the loop area of the aerial/receiver that each flow return loop creates.
It also reduces the effectiveness of the aerial/receiver function since alternate turns of the twist cancel the EMI radiated or received.
Once you have the layout finalised and the transformer rotated to find minimum (null) radiated field you can reduce the length of each twisted pair to the minimum.
Hi AndrewT,
this sentence "the transformer rotated to find minimum (null) radiated field" sounds intresting, what do you mean exactly?
Kr,
tent:wq
PS: still having some noise hearable.. any suggestio on the ground wiring for this amp?
PS2: any suggestion on how to connect directly some headphones on this amp (I'd like to add this as an option in my pre..)
this sentence "the transformer rotated to find minimum (null) radiated field" sounds intresting, what do you mean exactly?
Kr,
tent:wq
PS: still having some noise hearable.. any suggestio on the ground wiring for this amp?
PS2: any suggestion on how to connect directly some headphones on this amp (I'd like to add this as an option in my pre..)
Tent,
What transformer are you using? I have used Antek toroidals for my last 3 chipamp projects and they are dead silent. From the pics above, there are no twisted pairs and the test rig was dead silent. The PSU might also have something to do with it...proven design used by many folks by Carlos Felipe. The board I used was from chipamp.com.
What transformer are you using? I have used Antek toroidals for my last 3 chipamp projects and they are dead silent. From the pics above, there are no twisted pairs and the test rig was dead silent. The PSU might also have something to do with it...proven design used by many folks by Carlos Felipe. The board I used was from chipamp.com.
An EI transformer radiates high magnetic fields in many directions.
A toroid transformer radiates a low magnetic field in many directions, but radiates a high magnetic field in a few directions.
If the toroid is installed such that one of these high field radiation peaks passes across a loop receiver then that will induce hum in the amplifier.
One can rotate the toroid to try to achieve a null in induced hum.
This can be done if the toroid has long flexible (stranded) twisted mains and output leads.
Once the Null position is found then the mains and secondary twisted leads can be shortened to the minimum.
A toroid transformer radiates a low magnetic field in many directions, but radiates a high magnetic field in a few directions.
If the toroid is installed such that one of these high field radiation peaks passes across a loop receiver then that will induce hum in the amplifier.
One can rotate the toroid to try to achieve a null in induced hum.
This can be done if the toroid has long flexible (stranded) twisted mains and output leads.
Once the Null position is found then the mains and secondary twisted leads can be shortened to the minimum.
Hi,
ok, so you mean rotating it like I would do with a disc? I mean horizontally?
So, if it would be like a clock, being the primary and secondary wires the 12hours: could it be that, let's say at 4hours and at 8hours some high field radiation is coming out? and I should adjust this to make those, point out of my case, and not towards the pre-amp? wow, this would be a big news for me!
Anyway I'm using some no-name toroid.. do you think I should try with some better brand? I will try with the PSU from chipamp that cjkpkg is using since I have one of those lying around and will tell you if that is maybe doing some better.
But couldn't it be somehow because of the grounding that I should do better? I'm also kind of worried because the L and R channel grounds are "common"..
tent:wq
ok, so you mean rotating it like I would do with a disc? I mean horizontally?
So, if it would be like a clock, being the primary and secondary wires the 12hours: could it be that, let's say at 4hours and at 8hours some high field radiation is coming out? and I should adjust this to make those, point out of my case, and not towards the pre-amp? wow, this would be a big news for me!
Anyway I'm using some no-name toroid.. do you think I should try with some better brand? I will try with the PSU from chipamp that cjkpkg is using since I have one of those lying around and will tell you if that is maybe doing some better.
But couldn't it be somehow because of the grounding that I should do better? I'm also kind of worried because the L and R channel grounds are "common"..
tent:wq
Banned
Joined 2002
Where did you order your alps pot from ? i have been looking for a alps black beauty but can't find any
Looks good tho, any pictures of your chassis idea ?
With toroids, you should have a lot less problems than with an EI traffo. Still, since no winding is absolutely perfect, if you do notice induced issues, simply rotating the trafo could help you out.
As AndrewT mentions, do keep the wires nice and tightly would around each other. And if you do need to cross signal and power lies in the chassis, do try to do that at 90 degrees angle to reduce any possibility of interference. Don't worry too much about your toroid, however, they can be a problem only when done really bad and yours seems to be alright just by its looks. Still, you do benefit from keeping it away from sensitive circuits.
You generally want to keep all wiring as short as possible in the selected chassis and layout. After you've got your layout set-up and tested, trim everything to its possible minimum.
You shouldn't have problems with a single PSU, given that it can handle the currents, but some channel decoupling with capacitors couldn't hurt.
If you can hear noise/hum/buzz with the input shorted, you should look for the possibility of induced signal from trafo/mains-wiring or better PSU filtering. If not, you're all good to go.
With an extra headphone output you might need to consider output resistors to target impedance/stability issues. With my headphone amp I did need output resistors to make it completely silent at high volumes and no signal and match the (in some cases) expected output impedance for an headphone amp. Now, I might have done something wrong in the layout, but it has been mentioned that some headphones are tested and specced at a certain, slightly higher, output impedance of the source. ( I was never too sure about that, so other people might have better input on this topic. It's a good chance I did something not entirely correct in my layout, I am not an expert yet, at any rate) If you don't need it hard-wired, you might put a switch for preamp/headphone output.
At any rate, with your hardware, you shouldn't come across big issues so go ahead, be cautious with the mains and tell us how it sounds like.
Oh, and don't forget - twisting L/R channel wires together is not beneficial. Twisting positive/negative wires is.
As AndrewT mentions, do keep the wires nice and tightly would around each other. And if you do need to cross signal and power lies in the chassis, do try to do that at 90 degrees angle to reduce any possibility of interference. Don't worry too much about your toroid, however, they can be a problem only when done really bad and yours seems to be alright just by its looks. Still, you do benefit from keeping it away from sensitive circuits.
You generally want to keep all wiring as short as possible in the selected chassis and layout. After you've got your layout set-up and tested, trim everything to its possible minimum.
You shouldn't have problems with a single PSU, given that it can handle the currents, but some channel decoupling with capacitors couldn't hurt.
If you can hear noise/hum/buzz with the input shorted, you should look for the possibility of induced signal from trafo/mains-wiring or better PSU filtering. If not, you're all good to go.
With an extra headphone output you might need to consider output resistors to target impedance/stability issues. With my headphone amp I did need output resistors to make it completely silent at high volumes and no signal and match the (in some cases) expected output impedance for an headphone amp. Now, I might have done something wrong in the layout, but it has been mentioned that some headphones are tested and specced at a certain, slightly higher, output impedance of the source. ( I was never too sure about that, so other people might have better input on this topic. It's a good chance I did something not entirely correct in my layout, I am not an expert yet, at any rate) If you don't need it hard-wired, you might put a switch for preamp/headphone output.
At any rate, with your hardware, you shouldn't come across big issues so go ahead, be cautious with the mains and tell us how it sounds like.
Oh, and don't forget - twisting L/R channel wires together is not beneficial. Twisting positive/negative wires is.
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I have a question on grounding. I am using the chipamp.com PSU board and neither board has a hookup point to chassis ground. The only grounding is accomplished through the input/output jacks which are isolated from the chassis.
I may be overthinking things but I would think I would want an earth ground somewhere no?
I may be overthinking things but I would think I would want an earth ground somewhere no?
OK,
I have finalized the chassis...however, I made one major blunder...two of the RCA jack holes I drilled in the back panel was too close to the side and I had to abandon and re-drill two more holes...ahhhh!
Other than that...I have mounted the toroid, boards, and twisted all A/C lines and shortened everything I could.
The result??? very quiet preamp. I am running it now with my CNX TA2022 amp, the one on the bottom is a chipamp.com LM3886 amp. I have yet to try it with my KT88 SimpleSE...
The only gripe I have so far is that compared to my Aikido preamp, the UPC lacks some bass...I may try some "chip rolling" (currently running OPA2227P) with a couple other dual opamps to see what is what. Opamps are a little cheaper than tubes so this will be a fun experiment...
All in all, this was a very inexpensive experiment and the result exceeds my expectations.
I have finalized the chassis...however, I made one major blunder...two of the RCA jack holes I drilled in the back panel was too close to the side and I had to abandon and re-drill two more holes...ahhhh!
Other than that...I have mounted the toroid, boards, and twisted all A/C lines and shortened everything I could.
The result??? very quiet preamp. I am running it now with my CNX TA2022 amp, the one on the bottom is a chipamp.com LM3886 amp. I have yet to try it with my KT88 SimpleSE...
The only gripe I have so far is that compared to my Aikido preamp, the UPC lacks some bass...I may try some "chip rolling" (currently running OPA2227P) with a couple other dual opamps to see what is what. Opamps are a little cheaper than tubes so this will be a fun experiment...
All in all, this was a very inexpensive experiment and the result exceeds my expectations.
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I spent the last half hour listening to XM Holiday Pops with the UCP and my SimpleSE with KT88s and James6123HSs. This has been the most magical of all combinations.
The chipamps(TA2022 and LM3886) seem to hide something...the tube amp really shines with this preamp. Although I'm not convinced it sounds better than the Aikido...
The chipamps(TA2022 and LM3886) seem to hide something...the tube amp really shines with this preamp. Although I'm not convinced it sounds better than the Aikido...
I replaced the OPA2227P's tonight for a pair of LT1358CN8's...the LT1358's so far have a more full range to them. The highs are higher and the bass is better.
I am playing this through a CNX TA2022 amp and a pair of Fonkens with Enabled FE127E drivers....
I have 2 more opamps to try out...I will report my results with the UCP...
This is a great preamp with lots of opportunity to customize.
Regards,
Carl
I am playing this through a CNX TA2022 amp and a pair of Fonkens with Enabled FE127E drivers....
I have 2 more opamps to try out...I will report my results with the UCP...
This is a great preamp with lots of opportunity to customize.
Regards,
Carl
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hi,
nice making!thanks for the review.
P.S.
the UCPV2smt test board was in my hand.I will do a test in a couple of days.the updated of UCPV2smt:
1,mono design,single opamp with lme496**
2,pcb size 39mm x 39mm,as same as UCPV1smt
3,multi feedback loop available
P.S.P.S
has anybody tested the UCP with bridge mode?recently i built a summing box for a recording room.i use UCP as core,it is wonderfulzang
nice making!thanks for the review.
i am interested.i think it caused by the opamp drive ability and the power amp input network.
P.S.
the UCPV2smt test board was in my hand.I will do a test in a couple of days.the updated of UCPV2smt:
1,mono design,single opamp with lme496**
2,pcb size 39mm x 39mm,as same as UCPV1smt
3,multi feedback loop available
P.S.P.S
has anybody tested the UCP with bridge mode?recently i built a summing box for a recording room.i use UCP as core,it is wonderful
zangAttachments
Banned
Joined 2002
hi,
nice making!thanks for the review.
i am interested.i think it caused by the opamp drive ability and the power amp input network.
P.S.
the UCPV2smt test board was in my hand.I will do a test in a couple of days.the updated of UCPV2smt:
1,mono design,single opamp with lme496**
2,pcb size 39mm x 39mm,as same as UCPV1smt
3,multi feedback loop available
P.S.P.S
has anybody tested the UCP with bridge mode?recently i built a summing box for a recording room.i use UCP as core,it is wonderful
Good work Digi, keep it up
Okay, weird. I'd say its very rare for the chipamp.com kit to "hide something" because it does have that tendency to shout and that thing really is its crystal clear. Normally a "far too much" and this may be the very first report of "not enough." Except for the wack frequency response the chipamp doesn't "add something." If your tube amp features either a slightly brash tube or an Elna Cerafine (hint), then that may be adding an extrapolation that the chipamp doesn't do (unless you make it do that).
the R9,R10 value should be modified for headphone load.47ohm for low-Z headphones,200ohm for high-Z.the new smt resistors can be solder on the original R9,R10(connected in parallel).the opamps should choose be able to deliver high current values and to drive low impedance loads.and you will use a switched stereo jack to route the output sginal between jack&RCA.
the UCPv2smt use LME49600 buffer as output,it is powerful handle all kinds of loads
zang- Status
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