Acurus upgrade kits for RL-11, L10 & L11

R1200S

R1200S

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Foot of Mt. Belzoni
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Smoke and mirrors baby!
I thought some of you would be interested in these upgrade kits that are posted on eBay. They're posted by seller kchamber. Before you jump over there you should know that this seller has been at the forefront of Acurus/Aragon upgrades for years now. I don't know of anyone more knowledgeable on Acurus or Aragon gear. He's an electrical engineer that used to work for National Semiconductor (Dallas area) back in the day and is a hardcore audio hobbyist.

One of the RL-11's I own was fully upgraded by him a while back and includes an OUTBOARD power supply. It's quite incredible!! I'll try to post pictures of the inside and out in the next week or so. I don't really know if the upgrades to my unit are the same as what's in these kits but you can count on him knowing what he's doing.

RL-11 kit:
http://www.ebay.com/itm/Acurus-RL11...883298?hash=item2cbc8c77a2:g:u8gAAOSwc-tY2cs0

L10 & L11 kit:
http://www.ebay.com/itm/Acurus-L10-...864684?hash=item2cbc8c2eec:g:YSoAAOSwDKtY2cf7

Please read the description closely. It appears the price difference is one capacitor.
 
48 bucks for 15.00 worth of components seems excessive...but hey, if it improves the noise level, why not? Although when I tested my L11, residual noise was only 28 MICRO VOLTS , that's pretty damn quiet. What have you noticed with your upgraded unit?
 
I hesitate to comment as I'm not sure that the upgrades to my unit are the same as what's being offered in those listings. The improvements I'm hearing could be due to the upgraded outboard power supply. The biggest difference I hear on my RL-11 is a fuller, punchier overall sound to the music.
Swapping the preamps out for a fully comparison I haven't done yet. Lots more happening in my life right now that's eating up my time. I also thought the price might be a little high but then again, you're also paying for the seller's expertise and experience with upgrading Acurus preamps.
 
laatsch55 said:
48 bucks for 15.00 worth of components seems excessive...but hey, if it improves the noise level, why not? Although when I tested my L11, residual noise was only 28 MICRO VOLTS , that's pretty damn quiet. What have you noticed with your upgraded unit?
Click to expand...

How do you test for residual noise Lee? I think I am going to have Perry freshen up my Perreaux SA3 since it's bone stock never been worked on and I would like him to do the same test when done
 
Ron, residual noise measurements are taken with the analyzer hooked to the device under test, with the source selection on whatever you want checked, then shorting plugs in those jacks. The AP is internally grounded with a 39k resistor when the generators are off. Then the output of the preamp is hooked to the input of the AP and a sweep of between 10hz and 80khz is run. I b set mine up for 150 step "slow" sweep. A record is,made of any artifacts at the tested frequency, expressed in volts. You can also select manual mode and see the noise at ANY frequency between 10hz and 120khz....
 
Stephen, in Phoenix, has a 15,000.00 preamp. You can select between AC and battery power.. he did an A/B comparison during some Shpongle this time down and there was a noticeable difference. But again, the resolution of the other components in his collection is extrordinary, so whether a difference could be heard on most systems is questionable...
 
I ended up washing and drying a new 63V 2200uF cap about a week ago and it seems no worse for the adventure but I do wonder if it's cleaner sounding now?

Maybe it's SANFORIZED...
 
^^^^ IT puts the lotion on IT's skin or else IT gets the hose again... ^^^^ Orange, your getting on many nerves here, please stop the nonsense, thank you!! :angryfire:
 
I'm sorry if I upset you, Craig. I got a PM about it but don't quite understand. But I really don't want to make you mad at me.
 
Acurus L10 & LS11 Preamplifier performance upgrade kit

R1200S told me the past week that he had posted about the Acurus kits I was offering on Ebay so curiosity got the better of me and I thought I'd check out this thread.

Just a little info. The kits are designed to help those that may only know how to operate a soldering iron but do not understand how to select the parts they need. Probably half of the folks that contact me to do some upgrade work on their Acurus also ask if I could offer them a kit to recap their pre on their own. Due to a lack of free time I've had to stop doing work for others and I thought I'd offer a kit for people to be able to replace parts themselves. This kit is a basic performance kit, there are some other things that can be done to these pre's but the average guy with a soldering iron would probably get into trouble.

As far as what can be done to improve the Acurus pre's further. If you've ever popped the cover on the upper tier siblings the Aragon 18k or Aurum Pre's you'll get some ideas. The areas where Acurus cut corners are, lack of an active current source on the differential input in the Acurus where the Aragon 18k and Aurum got a proper current source on their diff input, the Aragon's also used the more expensive RN-60 style metal film resistors throughout, the Aragon power supply was massively overbuilt using a 30va transformer into a regulated supply in the IPS then fed to a CRC filter before going to the discrete regulators inside of the Aragon pre chassis. The Acurus in comparison uses a 5VA transformer feeding a pair of 3,300uF caps and no other filtering prior to the discrete regulators.

I have an RL11 on the bench and I've done a little work to it so far, primarily in the power supply, I have boosted the supply up with an external supply using a 10VA toroidal transformer and 2A soft recovery diodes and CRCRC prefiltering before the stock regulators. The only other mods inside of the pre are the same Nichicon capacitors and signal path resistors I included in the kits. I plan to eventually retrofit an active current source to the input diff pair and do a full swap of the resistors to the RN-60 style resistors.

I did a quick residual noise check using my old Option 1 equipped HP 339A which has a 100uV measuring range. Base residual noise on my HP 339A is 4.5uV with the meter input shorted with a 1k ohm plug. The residual noise from the modded RL-11 on my bench shows 16.5uV. These measurements were both made using the 80kHz LP filter on the HP339A to approximately simulate the AP 80kHz measuring range that laatsch55 is using. Laatsch55 I'm not sure what the residual of your AP is, but I'd bet being a much newer piece of gear its probably a bit lower than my 339A's 4.5uV. Some day maybe when the kids are all out of college and I've got some spare money I'll get an AP and move out of the stone age..... :toothy8:

Just an FYI for anyone measuring the Acurus or Aragon pre's, no shorting plugs are needed in the input RCA's. When you move the power knob to the "OFF" or "Mute" position you are effectively shorting out the input to the line amp. The knob positions "Off" and "Mute" really are the same thing on these pre's only Mute will leave the green power LED on, or turn it red on the RL11 and 28K. The line stage is always powered on as long as you have it plugged into the wall, so "Off" is not really off, its really "Mute" without the green LED.
 

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Mondialfan, nothing wrong with the 339, good piece of test gear. If you are getting 16.5uv after your mods what are your before measurements??

BTW, welcome to Phoenix. Any input is appreciated around here!!
 
laatsch55 said:
Mondialfan, nothing wrong with the 339, good piece of test gear. If you are getting 16.5uv after your mods what are your before measurements??

BTW, welcome to Phoenix. Any input is appreciated around here!!
Click to expand...

Unfortunately I didn't measure the residual prior to the upgrade work on this RL11. I have a small set of parameters I check/measure before a preamp upgrade to verify it is operating properly and residual is not one of the things that I check. Yeah I know, the final residual numbers without the pre-upgrade numbers do not show the entire picture, but I thought I'd give those numbers regardless. If I get another stock Acurus pre on the bench I'll measure pre and post residuals on it for you guys.

Don't get me wrong I like the 339 it'd just be nice if it had some automated functionality like the AP. I was using an old 334A before I got the 339.
 
Yeah, the AP is an awesome analyzer, it's automatic functions allow an amateur like me to make some consistent readings. The sweep functions are amazing. .I believe the AP residual is 1.2, but I'd have to dig the specs out to confirm that.
 
Welcome Mondialfan! Glad you popped in. I'm sure a few of us have checked you out already, have seen your mark around myself. Always great to hear from someone with knowledge and passion.
 
laatsch55 said:
So.
..what do you check pre-upgrade?
Click to expand...

> Power draw from the wall, I use a cheap little killawatt meter for this
> +/- DCV both before and after the regulators
> DC offset across the coupling caps
> THD + N @ 2V out, 1kHz, 10kHz, & 20kHz. While performing this test I also take the opportunity to measure output voltage to make sure freq response is flat out to 30kHz.

I'm most concerned with making sure someone hasn't sent me a problem before I begin any work and I have found a few. I have to accept responsibility for any existing issue once I've torn into it if I haven't identified it beforehand.
 
laatsch55 said:
Yeah, the AP is an awesome analyzer, it's automatic functions allow an amateur like me to make some consistent readings. The sweep functions are amazing. .I believe the AP residual is 1.2, but I'd have to dig the specs out to confirm that.
Click to expand...

Yes the repeatable tests are the big thing. Having a manually operated system always sets you up for a variable that you may have introduced because you had a knob or switch set in the wrong position. You have to be very vigilent and methodical if you want to reproduce the same test every time.

I think we're all amateurs when compared to the likes of Carver, Pass, Cordell, Curl, etc.

I like the term extreme hobbiest it sounds better than amateur. I'd say if you own an AP and know how to operate it you'd definitely qualify as an extreme hobbiest...
 
Really, I'm just a glorified parts changer.....but I do know my way around a White Oaked Phase Linear 400 or 700....those I know WELL......


I hear ya on the checking for problems before starting work, it does increase your bargaining position!!

I hope ya stick around and throw in your 2 cents worth once in awhile..

I did run a complete suite of tests on my Acurus, I had a thread in Pre-amps....
 
Are you the same guy that had all the Aragon threads on AK??
 
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