Hi Jkeny,
Thanks for the clock information.
I'm still trying to figure which muting transitors are the ones Mike removed. I thought they might be Q733 and Q736 before the sub transformer. I tested to see if these were the ones, but bypassing them didn't seems to help. Maybe this has been corrected in the newer receivers or the transitors must be higher up in the signal chain.
I did put in some poly filter caps at the speakers binding posts and this did help in darken the background.
I'm currently looking into changing all the diodes prior to the main transformer with fast soft recovery diodes. Do you have any favorite brands here?
I will try to post some pics of the new caps when work slow down a little.
🙂
Thanks for the clock information.
I'm still trying to figure which muting transitors are the ones Mike removed. I thought they might be Q733 and Q736 before the sub transformer. I tested to see if these were the ones, but bypassing them didn't seems to help. Maybe this has been corrected in the newer receivers or the transitors must be higher up in the signal chain.
I did put in some poly filter caps at the speakers binding posts and this did help in darken the background.
I'm currently looking into changing all the diodes prior to the main transformer with fast soft recovery diodes. Do you have any favorite brands here?
I will try to post some pics of the new caps when work slow down a little.
🙂
Yeh, I wondered myself which were the muting transistors - on the XR57 I figured it was the Q6081 muting transistors & on the 55 it seems to be Q6005 Q6006
So you were running the speakers without the final emi suppression caps before this? - adding them back improved things?
Changing the main rectfier brdige for fast soft-recovery diodes is probably a good idea - don't know about the other diodes though!
I will be using SBYV28-200 diodes because I have some & they're good (recommended by Hugh Dean of AKSA amp fame http://www.aksaonline.com/faqs/faqs_power.html#pq2) but there may be better ones out there now.
When you get a chance it would be great if you could write up your mods & what you thought of the change in sonics for each one, something like Hanguy's write-up.
This would aid me greatly in summarising all the mods you've made (I've kinda lost track) & would probably aid anybody else who might be reading this thread! At the moment this seems to be just a two-way dialogue!
So you were running the speakers without the final emi suppression caps before this? - adding them back improved things?
Changing the main rectfier brdige for fast soft-recovery diodes is probably a good idea - don't know about the other diodes though!
I will be using SBYV28-200 diodes because I have some & they're good (recommended by Hugh Dean of AKSA amp fame http://www.aksaonline.com/faqs/faqs_power.html#pq2) but there may be better ones out there now.
When you get a chance it would be great if you could write up your mods & what you thought of the change in sonics for each one, something like Hanguy's write-up.
This would aid me greatly in summarising all the mods you've made (I've kinda lost track) & would probably aid anybody else who might be reading this thread! At the moment this seems to be just a two-way dialogue!
Hi jkeny,
Here are some pics that includes some of the mods I have done to the SAXR55 recently:
Dayton 1uF binding post filter caps:
Vishay .47uF 715P and Nichicon KZ 1000uF power caps
The following is C707 possible replacement, probably will update this cap at the same time as upgrading the bridge diodes.
The Vishay SBYV28-200 looks like a really nice option. So we will have to build the bridge from scratch?
A quick list of all my current mods and prices vs. return performance is a great idea, I will do that as soon as I get some time.
Here are some pics that includes some of the mods I have done to the SAXR55 recently:
Dayton 1uF binding post filter caps:
Vishay .47uF 715P and Nichicon KZ 1000uF power caps
The following is C707 possible replacement, probably will update this cap at the same time as upgrading the bridge diodes.
The Vishay SBYV28-200 looks like a really nice option. So we will have to build the bridge from scratch?
A quick list of all my current mods and prices vs. return performance is a great idea, I will do that as soon as I get some time.
Nice pics eld,
Am I right in thinking you've got an extra 10,000uF in the PS now?
The C707 replacement is to cut down on any PS ripple, I take it? The new rectifier should help. Sorry, I actually have the BYQ28E-200 diodes, I got mixed up. These are dual diodes (slightly more expensive) so only 3 are needed for a bridge and 3 can be orientated so that they are in physical contact so the issue of thermal imbalance is somewhat alleviated.
Did you try the muting transistors? Are they the one's I identified?
Thanks eld, a write-up would be great when you get a chance!
Am I right in thinking you've got an extra 10,000uF in the PS now?
The C707 replacement is to cut down on any PS ripple, I take it? The new rectifier should help. Sorry, I actually have the BYQ28E-200 diodes, I got mixed up. These are dual diodes (slightly more expensive) so only 3 are needed for a bridge and 3 can be orientated so that they are in physical contact so the issue of thermal imbalance is somewhat alleviated.
Did you try the muting transistors? Are they the one's I identified?
Thanks eld, a write-up would be great when you get a chance!
A far cheaper option for your rectifiers might be these: http://search.digikey.com/scripts/dksearch/dksus.dll?Detail?name=DSEI12-06A-ND
<$2 each and they go up to 600V. I'm interested in these myself for a tube amplifier so if your going to purchase from Digikey could I purchase some also, through you?
Email me if you are interested!
<$2 each and they go up to 600V. I'm interested in these myself for a tube amplifier so if your going to purchase from Digikey could I purchase some also, through you?
Email me if you are interested!
Eld,
You replaced/added the 1.0uf dayton filter caps to ground on the new binding posts you added. I thought the stock value was 1000 Picofarads (on the XR-55)? You should have used 0.001 uf dayton caps instead. Maybe I am wrong here? Just trying to clarify.
Oh by the way, Use a Jensen 4-pole in the SMPS. I used a 1000uf/200v 4-pole. Did this a couple years ago on my XR-55 when I got it. Very nice improvement in bass/slam and depth. Stock it was too 1-notish I thought.
Thanks.
You replaced/added the 1.0uf dayton filter caps to ground on the new binding posts you added. I thought the stock value was 1000 Picofarads (on the XR-55)? You should have used 0.001 uf dayton caps instead. Maybe I am wrong here? Just trying to clarify.
Oh by the way, Use a Jensen 4-pole in the SMPS. I used a 1000uf/200v 4-pole. Did this a couple years ago on my XR-55 when I got it. Very nice improvement in bass/slam and depth. Stock it was too 1-notish I thought.
Thanks.
Good point Crazy-D, about the binding post filter caps!
Where/what price did youy get the Jansen 1000uf/200v 4-pole cap - I can't seem to find any on the interweb.
I came accross something the other day about a HQ sound mode on the SA-XR70 which turns off the display. I've heard about display ICs switching contaminating the main PS before & it's a technique used on other equipment! I'm going to look into a possible mod along these lines also!
Where/what price did youy get the Jansen 1000uf/200v 4-pole cap - I can't seem to find any on the interweb.
I came accross something the other day about a HQ sound mode on the SA-XR70 which turns off the display. I've heard about display ICs switching contaminating the main PS before & it's a technique used on other equipment! I'm going to look into a possible mod along these lines also!
Thanks Crazy-D!
One of my many mistakes, I need to correct the Filter-caps values. Do you have any idea why the caps should be .001uF? What do you guys think about .01uF or .1uF instead? It is strange that the system sounds pretty good with the 1uF there. I just did a quick low pass filter calculation and it looks like at 8 ohms the filter frequency will be at 20Khz and 4 Ohms at 40Khz for the 1 uF value. Maybe it sounds ok with the Dynaudios hovering around 4 Ohms?
So Jensen 4 poles is the way to go, thanks Crazy-D. Did you change the diodes bridge as well?
Jkeny,
I'm actually looking at Fairchild Stealth II (FFP08S60S) as the diodes for the bridge.
Thanks guys!
One of my many mistakes, I need to correct the Filter-caps values. Do you have any idea why the caps should be .001uF? What do you guys think about .01uF or .1uF instead? It is strange that the system sounds pretty good with the 1uF there. I just did a quick low pass filter calculation and it looks like at 8 ohms the filter frequency will be at 20Khz and 4 Ohms at 40Khz for the 1 uF value. Maybe it sounds ok with the Dynaudios hovering around 4 Ohms?
So Jensen 4 poles is the way to go, thanks Crazy-D. Did you change the diodes bridge as well?
Jkeny,
I'm actually looking at Fairchild Stealth II (FFP08S60S) as the diodes for the bridge.
Thanks guys!
Hi eld,
That cut-off freq is way too close to 20KHz - you would have heard this have an effect on the music, I believe!
Have you found anywhere that sells 4-pole Jensen 200V caps at a reasonable price?
I would be interested in sharing in the purchasing of any parts as Digikey operate an expensive delivery to Ireland & customs will also hit me. I can pay you any way you like. So if you can facilitate me I would be delighted! Please email me!
These FFP08S60S look good!
Here's what I was talking about taken from the SA-XR70 User manual:
I can see where the display could be turned off in the existing PS circuit but I need to get the XR70 Service manual to see how this is implemented exactly - migth be worth considering? We'll see
That cut-off freq is way too close to 20KHz - you would have heard this have an effect on the music, I believe!
Have you found anywhere that sells 4-pole Jensen 200V caps at a reasonable price?
I would be interested in sharing in the purchasing of any parts as Digikey operate an expensive delivery to Ireland & customs will also hit me. I can pay you any way you like. So if you can facilitate me I would be delighted! Please email me!
These FFP08S60S look good!
Here's what I was talking about taken from the SA-XR70 User manual:
I can see where the display could be turned off in the existing PS circuit but I need to get the XR70 Service manual to see how this is implemented exactly - migth be worth considering? We'll see
Jkeny,
I sent you an email, let me know what you are thinking of getting from Digi-key or Mouser.
Do you think the filter freq is actually that bad if the inline resistance is correct? The filter cap with a 1st order rolloff at 20Khz in 8 Ohms matches the rolloff frequency of my tweeter. But since I don't really know what's going on and maybe the resistance or impedance is much higher? I'm going to change it back to 1nF with Vishay 715P's, trusting the Panasonic Engineers. Looking at the poor stock speaker power lines, maybe cost is more of a factor here, but I have no idea!! 🙂
I sent you an email, let me know what you are thinking of getting from Digi-key or Mouser.
Do you think the filter freq is actually that bad if the inline resistance is correct? The filter cap with a 1st order rolloff at 20Khz in 8 Ohms matches the rolloff frequency of my tweeter. But since I don't really know what's going on and maybe the resistance or impedance is much higher? I'm going to change it back to 1nF with Vishay 715P's, trusting the Panasonic Engineers. Looking at the poor stock speaker power lines, maybe cost is more of a factor here, but I have no idea!! 🙂
Hi guys,
Here is my review of my current mods. I’m only about half way done, and so far, I have concentrated mainly on the power supply since this is where I think the stock units are most lacking. I will try to keep this as brief as possible. Here is some background information:
Basic information:
Dedicated AC line—70’ 10AWG run w/ Pass & Seymour 5362A outlet
Speakers—Dynaudio Audience 82’s and Audience 122c
Sub—Behringer EP2500/Eclipse SW8200
Reference Music—Eagles, Eurythmics, Celine Dion, Nhu Quynh
Solder—Cardas Quad-Eutectic
Scale:
0-10, with 10 being the best
Reference Amps and My Relative Score: (H-Highs, M-Mids, B-Bass)
Rotel 1080 (H=5.5, M=6.5, B=8.0)
Rotel 1092 (H=8.5, M=7.0, B=5.0)
Stock SAXR55 (H=7.0, M=2.0, B=2.0)
MOD-#1: Power Cord and Plug Upgrade ($97)
Stock:2-18AWG conductors with molded plug and C7 chassis connections
Upgrade: Replaced stock cord and pulg with Neotech NEP-3003 ($14 x 3ft) and Furutech FM-11 (G) ($40). Direct solder the leads to the first line coil on the bottom side of the power board. Be careful to keep polarity of the power cords correct. Provided (2) 0.47uF Sonicap ($15) between the two power leads (I have read that Auricaps are usually used here, but I went with Sonicaps)
Improvement: (H=+0.5, M=+1.5, B=+1.0)
MOD-#2: Rewiring the internal speaker lines and add Cardas CCGG Posts ($81)
Stock:Cheap posts, tiny wires and extra long runs
Upgrade: Replaced stock posts with Cardas CCGG ($25 x3 pairs) and rewire speaker power lines (~$6 Audioquest cables)
Improvement: (H=+0.5, M=+1.5, B=+1.0)
MOD-#3: Add more PS caps ($23)
Stock:2,000uF share PS caps.
Upgrade: Added 10,000uF of Nichicon Muse KZ ($1.55x10) and Vishay .47uF caps ($.80 x10)
Improvement: (H=+0.5, M=+.5, B=+.5)
So far I feel that the mod unit is around (H=8.5, M = 5.5, B = 4.5). Can’t wait to see what the next several mods of adding the Jensen 4-poles, upgrading RCAs, and adding the soft recovery diodes will do.
Hope that helps a little.
Cheers,
Eld
Here is my review of my current mods. I’m only about half way done, and so far, I have concentrated mainly on the power supply since this is where I think the stock units are most lacking. I will try to keep this as brief as possible. Here is some background information:
Basic information:
Dedicated AC line—70’ 10AWG run w/ Pass & Seymour 5362A outlet
Speakers—Dynaudio Audience 82’s and Audience 122c
Sub—Behringer EP2500/Eclipse SW8200
Reference Music—Eagles, Eurythmics, Celine Dion, Nhu Quynh
Solder—Cardas Quad-Eutectic
Scale:
0-10, with 10 being the best
Reference Amps and My Relative Score: (H-Highs, M-Mids, B-Bass)
Rotel 1080 (H=5.5, M=6.5, B=8.0)
Rotel 1092 (H=8.5, M=7.0, B=5.0)
Stock SAXR55 (H=7.0, M=2.0, B=2.0)
MOD-#1: Power Cord and Plug Upgrade ($97)
Stock:2-18AWG conductors with molded plug and C7 chassis connections
Upgrade: Replaced stock cord and pulg with Neotech NEP-3003 ($14 x 3ft) and Furutech FM-11 (G) ($40). Direct solder the leads to the first line coil on the bottom side of the power board. Be careful to keep polarity of the power cords correct. Provided (2) 0.47uF Sonicap ($15) between the two power leads (I have read that Auricaps are usually used here, but I went with Sonicaps)
Improvement: (H=+0.5, M=+1.5, B=+1.0)
MOD-#2: Rewiring the internal speaker lines and add Cardas CCGG Posts ($81)
Stock:Cheap posts, tiny wires and extra long runs
Upgrade: Replaced stock posts with Cardas CCGG ($25 x3 pairs) and rewire speaker power lines (~$6 Audioquest cables)
Improvement: (H=+0.5, M=+1.5, B=+1.0)
MOD-#3: Add more PS caps ($23)
Stock:2,000uF share PS caps.
Upgrade: Added 10,000uF of Nichicon Muse KZ ($1.55x10) and Vishay .47uF caps ($.80 x10)
Improvement: (H=+0.5, M=+.5, B=+.5)
So far I feel that the mod unit is around (H=8.5, M = 5.5, B = 4.5). Can’t wait to see what the next several mods of adding the Jensen 4-poles, upgrading RCAs, and adding the soft recovery diodes will do.
Hope that helps a little.
Cheers,
Eld
Hi eld,
Good write-up, thanks!
So, this is still a good bit below your Rotel ref amps. Haven't heard these amps but have seen the 1092 class D amp get good reviews.
I imagine that the final bits of improvement that can be squeezed out of this will be:
- PS rectifier = soft recovery, fast diodes
- PS cap = Jensen 4-pole
- PS bypass caps on selected audio ICs = SP-Caps or similar (X2Y MLCC caps, maybe)
- PS supply to output board = 3 or 4 12V SLA batteries (7aH) with capacitor bank
- clock = low jitter Tent or other clock with low noise PS supply
Anything else you're thinking of doing?
You mentioned the digital input circuits - any changes here?
Edit: For those interested here's a brilliant piece of bypass cap analysis done on over 140 cap combinations http://www.audiofaidate.it/forum/uploaded/caps_tests.zip
Good write-up, thanks!
So, this is still a good bit below your Rotel ref amps. Haven't heard these amps but have seen the 1092 class D amp get good reviews.
I imagine that the final bits of improvement that can be squeezed out of this will be:
- PS rectifier = soft recovery, fast diodes
- PS cap = Jensen 4-pole
- PS bypass caps on selected audio ICs = SP-Caps or similar (X2Y MLCC caps, maybe)
- PS supply to output board = 3 or 4 12V SLA batteries (7aH) with capacitor bank
- clock = low jitter Tent or other clock with low noise PS supply
Anything else you're thinking of doing?
You mentioned the digital input circuits - any changes here?
Edit: For those interested here's a brilliant piece of bypass cap analysis done on over 140 cap combinations http://www.audiofaidate.it/forum/uploaded/caps_tests.zip
to Eld
be careful with all that caps
you probably introduce resonances and EMI
i would simply replace the 1000uF "water" caps ( sounding bright ) for better 2200uF ( Elna or better Blackgate FK for example ) , these caps are near the switching Transistors and are influential
i would also put a pi filter on the ps cord to avoid garbage going out or in , like this :
http://www.sonelec-musique.com/electronique_realisations_filtre_secteur_002.html
in my experience it's enough to hear a good improvement
be careful with all that caps
you probably introduce resonances and EMI
i would simply replace the 1000uF "water" caps ( sounding bright ) for better 2200uF ( Elna or better Blackgate FK for example ) , these caps are near the switching Transistors and are influential
i would also put a pi filter on the ps cord to avoid garbage going out or in , like this :
http://www.sonelec-musique.com/electronique_realisations_filtre_secteur_002.html
in my experience it's enough to hear a good improvement
Thank you very much for your help, rha61.
This is my first mod unit, so any help is greatly appreciated. I too was worry about the resonance issue of introducing the bypass to the electrolytic as you pointed out earlier, but so far, with the Vishay, this resonance seems to be small and not noticable. The plus side is greater detail, smoother mids and less strain at high volume. I will keep from adding any more caps, though.
I have changed the speakers filter caps to 1nF to match factory values. The floor noise seems higher without these filters in place.
The Pi filter sounds great. I didn't know what it was until your suggestion, but it looks like the stock unit has a built in Pi filter.
Again, thank you for your help. I will post an update as soon as the Jensen and soft recovery diodes are in.
Cheers!
This is my first mod unit, so any help is greatly appreciated. I too was worry about the resonance issue of introducing the bypass to the electrolytic as you pointed out earlier, but so far, with the Vishay, this resonance seems to be small and not noticable. The plus side is greater detail, smoother mids and less strain at high volume. I will keep from adding any more caps, though.
I have changed the speakers filter caps to 1nF to match factory values. The floor noise seems higher without these filters in place.
The Pi filter sounds great. I didn't know what it was until your suggestion, but it looks like the stock unit has a built in Pi filter.
Again, thank you for your help. I will post an update as soon as the Jensen and soft recovery diodes are in.
Cheers!
jkeny,
The XEs are around 12.5mm x 25mm, I will try to measure them and let you know the next time I open up the unit (in a day or two).
Another possibility is following rha61 lead here, and remove all the XE caps and put a nice big one in their place.
I wonder if anyone have modded the XR55 and replaced these caps with anything better?
The XEs are around 12.5mm x 25mm, I will try to measure them and let you know the next time I open up the unit (in a day or two).
Another possibility is following rha61 lead here, and remove all the XE caps and put a nice big one in their place.
I wonder if anyone have modded the XR55 and replaced these caps with anything better?
One problem I always had with this approach is that usually bypass caps (low esr) should be as close to the IC as possible to avoid the added impedance of the pcb trace between cap and IC PS pin.
Now, maybe a smaller bypass cap with ultra low esr near to the PS pin overcomes this issue but as rha61 says, resonance issues have to be avoided with bypass caps.
It does bring me back to my original idea of taking out one XE cap and putting in 2 single pin sockets for plugging in various caps and/or cap combinations until a suitable alternative is found or not!
why a big cap ? because the experience shows that , for a same value , a bigger cap size sounds better ( no explanation for this )
for the ps caps near the switching Tr , i've put 100/50 Blackgte
the saxr45 has two pi filters ( if i remember ) and i add one , near the wall
for the ps caps near the switching Tr , i've put 100/50 Blackgte
the saxr45 has two pi filters ( if i remember ) and i add one , near the wall
So multiple Pi filters are worth it, thanks rha61. I will look into seeing what are good inductors to go along with the .47uF Sonicaps.
Have you gotten a chance to listen to the stock SAXR55-57 unit? Can you give us a run down on your SAXR45 mods and their relative sonic improvements? It would be a great help for comparison and indicating what additional mods need to be done. Thanks!
Have you gotten a chance to listen to the stock SAXR55-57 unit? Can you give us a run down on your SAXR45 mods and their relative sonic improvements? It would be a great help for comparison and indicating what additional mods need to be done. Thanks!
Yes, rha61, your knowledge in all of this is invaluable so anything you can tell us would be appreciated. Your experience of the caps is good practical info and saves us from making mistakes.
I'm hoping to have my SA-XR57 by end of next week so I'll be actively modding the amp after this not just theorising about it.
Did you find the blackgates worked well in this position, next to the trafo? What criteria do you use to select your caps or is it by informed trial and error?
Any other suggestions for improvements in the amp? What mod had the most effect for you?
Sorry for all the questions but it's great to have somebody who has throdden this path already!
I'm hoping to have my SA-XR57 by end of next week so I'll be actively modding the amp after this not just theorising about it.
Did you find the blackgates worked well in this position, next to the trafo? What criteria do you use to select your caps or is it by informed trial and error?
Any other suggestions for improvements in the amp? What mod had the most effect for you?
Sorry for all the questions but it's great to have somebody who has throdden this path already!
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