Canuck Audio Mart Hifi and Audio ForumCanuck Audio Mart Hifi and Audio Forum
It is currently Tue Oct 17, 2017 12:13 pm

All times are UTC - 8 hours




Post new topic Reply to topic  [ 187 posts ]  Go to page Previous  1 ... 6, 7, 8, 9, 10, 11, 12, 13  Next
Author Message
PostPosted: Sun Sep 04, 2016 2:39 pm 
Offline

Joined: Fri Jul 04, 2014 8:37 pm
Posts: 291
Location: Toronto, ON, CA
I'm terrible at wood works. I remembered my friend Peter (palladio) came to my place checked on SR71 speaker, he kind of "pet" the cabinet, after a short period of silent, he raised his head and said "allow me build a pair of cabinets for you"...he is indeed a master on wood works. And I have never built any speaker cabinets since then...lucky me

Back to the sound of AJ, using the same set up as F6. Just some first impression, personal, system, and build dependent...your build might have totally different result...
-Like F6, AJ is also very detailed...;
-AJ performs well from low to high, in a controlled way...good bass, not too tight, not loose...you can listen AJ as long as you want quite pleasantly...don't forget to turn it off or you will be surprised when electrical bill come;-)
-Both AJ and F6's sound staging are very good...F6's vocal appears a little more forward than AJ...but F6 sounds more "live"...
-F6's bass is also good, pleasant;
-My F6's high sounds a bit bright, probably due to Nichicon caps I used, will definitely try Elna Silmic II 1000uf caps see if can smooth the high a bit...comparing with Elna, Nichicon tend to sound a bit brighter or "hi-fi"...
-I believe AJ will sound good in almost all speakers (if it fits to drive), F6, on the other hand, has a "luster" in its sound, some people will love it "to death", some might not...

Which one I love more? Difficult question, parents love all their children equally is the correct answer.
Ok, I love F6 a bit more, can't resist its luster.


Top
 Profile  
Reply with quote  
 Post subject: Wires used in amps
PostPosted: Mon Sep 05, 2016 7:13 am 
Offline

Joined: Fri Jul 04, 2014 8:37 pm
Posts: 291
Location: Toronto, ON, CA
Regarding the wires, I use whatever handy when building the amp...

For LED wires, I used wires from RJ45 cable...
For power wires, I used computer power cables (stripped the black rubber) from brand names, such as HP, Dell, 10A wire for AC inlet to transformer, heavier gauge wires after bridge rectifiers (lower voltage, higher current there), normally stripped from workstation or server power cable. These are some decent copper wires, manufactured by some Taiwan giant companies.
Amp board to speaker binding posts, I used Wirelogic (Audioquest made for Costco) speaker wires;
RCA input I used Japan made silver plated multithread OFC wires, shield, twisted...
For ground wire, I use solid core OFC which I unwind from a conductor...

Some people might say "cheap"...I do have some more expensive wires, Cardas, Furutech, Neotech, and etc...I mean, if you can afford and willing to, you can use any wire pleased you, nothing wrong with that. Pricy wires normally look better...the same as we pursuit food, delicious is one thing in the functional requirement domain(sound), we also want the food served look good, or even feel good...No right or wrong here...I happen to have some computer/server power cables, and I like use them in amps to conduct current, soft and easier to handle...only one thing bad, they normally PVC insulated and unlike Teflon those PVC cannot stand heat as much as Teflon, so I use big chunk of metal to help dissipate heat immediately after solder on them to prevent PVC turn stiff ...that's all

After many DIY practice, I tend to use wires at "appropriate" place for amps:
-Copper wire for PS department;
-Silver plated wires for RCA input, in rare cases such as the high is already bright, then use copper instead;
-Copper speaker wire...
-Others do not matter, as long as meets safety and gauge requirements.

For preamp, and DACs, wires could bring big difference in some places...more sensitive to wires than amps, but not all over the places. Wires could serve a tuning purpose here.


Attachments:
File comment: RJ45 wire for LED connection
IMG_3362.jpg
IMG_3362.jpg [ 83.83 KiB | Viewed 668 times ]
Top
 Profile  
Reply with quote  
PostPosted: Mon Sep 05, 2016 1:21 pm 
Offline

Joined: Wed Sep 14, 2005 11:47 am
Posts: 3805
Location: Ottawa, ON, CA
As a general rule, I would not tie wrap the input cable to the output cable.
Even though the input is a shielded cable.

Maybe tie wrap them with a spacer in between.


Top
 Profile  
Reply with quote  
PostPosted: Mon Sep 05, 2016 1:52 pm 
Offline

Joined: Fri Jul 04, 2014 8:37 pm
Posts: 291
Location: Toronto, ON, CA
Uunderhill wrote:
As a general rule, I would not tie wrap the input cable to the output cable.
Even though the input is a shielded cable.

Maybe tie wrap them with a spacer in between.


It's a temp arrangement - using stiff input to hold speaker output cable away from input transformer or AC...

The impact is minor even binding them together...


Top
 Profile  
Reply with quote  
 Post subject: Regarding AJ thump
PostPosted: Mon Sep 05, 2016 6:15 pm 
Offline

Joined: Fri Jul 04, 2014 8:37 pm
Posts: 291
Location: Toronto, ON, CA
Uunderhill wrote:
....


Regarding AJ's thump, first I thought it is the uneven drain (just can't match the MOSFETs perfectly)...or maybe the power filter caps I used are too big (F6 is totally different story, you just can't make it thump;-) ...It puzzled me as I thought the original AJ should not have this thump...what did I do wrong!

Today, after a night's long sleep, I looked back to AJ manual, again, and very closely...surprisingly, Mr. Pass mentioned turn on/off thump in the manual! And here is the original statement "Turn-on and turn-off thumps and noise are small in this amplifier, and should not present a hazard to delicate drivers." Probably due to AJ is not symmetric (AJ is rather a 2 layer/stage topology)...
(page 3, the 2nd paragraph count from bottom)
http://www.firstwatt.com/pdf/prod_aj_man.pdf

The turn off thump is actually very mild, won't surprise the listener, milder than ACA (if using laptop PS, using transformer does not have any thump), that's why I did not noticed when first ran the amp...so it's normal and should in a good range.

Now, where is my turn on thump? Should I worried? Don't call me paranoid...


Top
 Profile  
Reply with quote  
PostPosted: Mon Sep 05, 2016 7:56 pm 
Offline
User avatar

Joined: Mon Mar 31, 2008 9:17 am
Posts: 13706
Location: Toronto, ON, CA
Frank Wang wrote:
Now, where is my turn on thump? Should I worried? Don't call me paranoid...
My Threshold S-150 has a turn-on thump. Nothing to be worried about at all.

_________________
To a hammer, everything looks like a nail


Top
 Profile  
Reply with quote  
PostPosted: Tue Sep 06, 2016 3:13 am 
Offline

Joined: Wed Sep 14, 2005 11:47 am
Posts: 3805
Location: Ottawa, ON, CA
I think amps with a differential pair and a feedback loop, would have a thump.

Basically the output stage needs to be biased, before feedback can be applied
to Q2 of the differential pair.
Then the differential pair can apply the correct Vgs to the power MOSFET of the output stage.
Catch 22.

However, with the Aleph J - I'm wondering if R24 and C3 are used to momentarily bias
the protection transistor Q4 - to help limit the current.

Also the 4 output power resistors in parallel, would help control the thump.


Top
 Profile  
Reply with quote  
PostPosted: Tue Sep 06, 2016 3:33 am 
Offline

Joined: Fri Jul 04, 2014 8:37 pm
Posts: 291
Location: Toronto, ON, CA
Uunderhill wrote:
I think amps with a differential pair and a feedback loop, would have a thump.

Basically the output stage needs to be biased, before feedback can be applied
to Q2 of the differential pair.
Then the differential pair can apply the correct Vgs to the power MOSFET of the output stage.
Catch 22.

However, with the Aleph J - I'm wondering if R24 and C3 are used to momentarily bias
the protection transistor Q4 - to help limit the current.

Also the 4 output power resistors in parallel, would help control the thump.


As long as the thump is "normal" - as per design, I'm totally ok, besides, it's mild and very short.

I'm wondering if the reason I don't have turn on thump is I used bigger caps...


Top
 Profile  
Reply with quote  
PostPosted: Wed Sep 07, 2016 3:13 am 
Offline

Joined: Wed Sep 14, 2005 11:47 am
Posts: 3805
Location: Ottawa, ON, CA
.


Top
 Profile  
Reply with quote  
PostPosted: Wed Sep 07, 2016 12:06 pm 
Offline

Joined: Fri Oct 16, 2009 7:42 am
Posts: 1406
Location: Toronto, ON, CA
Odd, both the F5 and F5Turbo V3 I built never had any turn on thump.
And they are differential pairs with feedback loop. And I took out any of the speaker protection that Pass originally designed into it.

Is there something else in the circuit that would prevent the thump?

_________________
Punctuation is important. It's the difference between "I helped my uncle, Jack, off a horse" and "I helped my uncle Jack off a horse"


Top
 Profile  
Reply with quote  
PostPosted: Wed Sep 07, 2016 2:27 pm 
Offline

Joined: Fri Jul 04, 2014 8:37 pm
Posts: 291
Location: Toronto, ON, CA
dazed2 wrote:
Odd, both the F5 and F5Turbo V3 I built never had any turn on thump.
And they are differential pairs with feedback loop. And I took out any of the speaker protection that Pass originally designed into it.

Is there something else in the circuit that would prevent the thump?


Don't have time to check the deep root cause why AJ comes with thump as per design yet...probably F5 is symmetric and AJ is not...
The thump is really minor, don't need to overthink it.

BTW:
I finally found the turn on thump on my AJ...it's very minor, and was "covered" by the sound when turn power switch on. Last night, I asked my wife to turn on the amp, and I pressed my ear against speaker, and indeed heard a tiny short thump...milder than the turn off.

Anyhow, if it's about pairing the MOSFETs or anything, it's impossible for DIYer or even manufacture...these things drift with temperature, even they end up the same value after 30 minutes warmup/stable, you cannot guarantee they always have the same value during that 30 minutes...

AJ is a good amp, the thump is minor, period. ;-)


Top
 Profile  
Reply with quote  
 Post subject: F5 Turbo
PostPosted: Fri Sep 09, 2016 8:37 am 
Offline

Joined: Fri Jul 04, 2014 8:37 pm
Posts: 291
Location: Toronto, ON, CA
Uunderhill, how is your F5 Turbo going? V2 or V3?

Curious what so called "high band-width" amplifier could be.

I'm using 24V transformers, so V2 it is...


Attachments:
F5T_Transformers.jpg
F5T_Transformers.jpg [ 181.28 KiB | Viewed 567 times ]
Top
 Profile  
Reply with quote  
 Post subject: Re: F5 Turbo
PostPosted: Fri Sep 09, 2016 12:59 pm 
Offline

Joined: Fri Oct 16, 2009 7:42 am
Posts: 1406
Location: Toronto, ON, CA
Frank Wang wrote:
Uunderhill, how is your F5 Turbo going? V2 or V3?

Curious what so called "high band-width" amplifier could be.

I'm using 24V transformers, so V2 it is...



High bandwidth amp, means it can amplify signal well into the super sonic levels. The F5 apparently is flat to 800 - 900 kHZ.

_________________
Punctuation is important. It's the difference between "I helped my uncle, Jack, off a horse" and "I helped my uncle Jack off a horse"


Top
 Profile  
Reply with quote  
 Post subject: Re: F5 Turbo
PostPosted: Fri Sep 09, 2016 2:52 pm 
Offline

Joined: Fri Jul 04, 2014 8:37 pm
Posts: 291
Location: Toronto, ON, CA
dazed2 wrote:
Frank Wang wrote:
Uunderhill, how is your F5 Turbo going? V2 or V3?

Curious what so called "high band-width" amplifier could be.

I'm using 24V transformers, so V2 it is...



High bandwidth amp, means it can amplify signal well into the super sonic levels. The F5 apparently is flat to 800 - 900 kHZ.


I know "high bandwith" definition...curious how it would sound differently comparing with other amps


Top
 Profile  
Reply with quote  
 Post subject: F5 Turbo V2
PostPosted: Sat Sep 10, 2016 6:41 pm 
Offline

Joined: Fri Jul 04, 2014 8:37 pm
Posts: 291
Location: Toronto, ON, CA
Solder the FE boards tonight...

Using Vishay MRS25 resistors (0.6W) for R1,R2, R5,R6, low ppm...one of my "favorite" resistors for amplifiers...Black ones are Vishay Dale 3W resistors, very low ppm...

Since it's V2, no cascoding needed, short Q7 2SC4793,Q8 2SA1837 transistors' C & E...

C1,C2 using Nichicon KZ 10uf/100V ...(C5,C6 not needed as no cascoding)

R25~R30 also not needed for V2

Will take some time match JFETs and put into FE boards

P1~P3, Bourns 3296...for P3, adjust to "center" before plug into PCB, note due to its tolerance(or DMM's tolerance), it's full resistance might not be 200R...in my case, I measured and adjust 2->1, and 2->3 (2 is wiper) to equally to circa 99R...

For Bourns trimmer, 2(wiper) normally is around center position...but not exact center.


Attachments:
IMG_3540.jpg
IMG_3540.jpg [ 287.35 KiB | Viewed 524 times ]
Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 187 posts ]  Go to page Previous  1 ... 6, 7, 8, 9, 10, 11, 12, 13  Next

All times are UTC - 8 hours


Who is online

Users browsing this forum: Google Adsense [Bot], murphman and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group