I think it was designed by William Synder who at one time was a production manager for Krell.
It was reviewed in the Audio Critic mag and got 2 thumbs up for the price.
I,m going from memory and might be off somewhat. There was a phono unit combination also and I might be thinking of that one...
Regards
David
It was reviewed in the Audio Critic mag and got 2 thumbs up for the price.
I,m going from memory and might be off somewhat. There was a phono unit combination also and I might be thinking of that one...
Regards
David
Thanks for the info. David.
I'm interested in the changes I saw here:
Ken Ealey Audio - Rebuild Packages - Acurus L10 and RL11 Preamplifiers
I've sent this guy a couple of emails, but so far no reply.
Apparently his mods are "shrouded in secrecy".
Nonetheless, I'm not going to pay somebody $250 to change out a few components.
Here are the changes/mods he supposedly performs:
-First, he replaces the BJT transistors with some type of mosfets.
These mosfets are handmatched to the millivolt level and provide true differential performance. A circuit MUST have this to provide the best symmetry.
- Second, the idle current is increased putting them in that famous "Linear, Class A" mode. The stock version has to run barely turned on at nothing more than a trickle current for DC offset purposes. This mosfet upgrade fixes all that and then some. It has repercussions throughout the circuit.
- Third, active current sourcing is used to bias the mosfets and takes the place of the single stock resistor. All aspects of performance are improved and the result is a real front end the way a front end is supposed to be done. Most manufacturers don't budget for this step because it costs too much and demands special attention since it does not lend itself to mass production. As good as the stock version sounds, this sounds better with solidified imaging, soundstage, and clarity.
If mosfets sound so much better, then I wonder why Mr. Snyder didn't use them to begin with?
I wouldn't mind trying some of these things on my L10, but it may be difficult without a schematic to see the original circuit.
I'm interested in the changes I saw here:
Ken Ealey Audio - Rebuild Packages - Acurus L10 and RL11 Preamplifiers
I've sent this guy a couple of emails, but so far no reply.
Apparently his mods are "shrouded in secrecy".
Nonetheless, I'm not going to pay somebody $250 to change out a few components.
Here are the changes/mods he supposedly performs:
-First, he replaces the BJT transistors with some type of mosfets.
These mosfets are handmatched to the millivolt level and provide true differential performance. A circuit MUST have this to provide the best symmetry.
- Second, the idle current is increased putting them in that famous "Linear, Class A" mode. The stock version has to run barely turned on at nothing more than a trickle current for DC offset purposes. This mosfet upgrade fixes all that and then some. It has repercussions throughout the circuit.
- Third, active current sourcing is used to bias the mosfets and takes the place of the single stock resistor. All aspects of performance are improved and the result is a real front end the way a front end is supposed to be done. Most manufacturers don't budget for this step because it costs too much and demands special attention since it does not lend itself to mass production. As good as the stock version sounds, this sounds better with solidified imaging, soundstage, and clarity.
If mosfets sound so much better, then I wonder why Mr. Snyder didn't use them to begin with?
I wouldn't mind trying some of these things on my L10, but it may be difficult without a schematic to see the original circuit.
There is a guy at the Danish HIFI forum who's had the mods done. There are schematics and some pictures of before and after in the thread. Quite interresting as it seems to me from those to you can deduce a lot about the mods. Link: HIFI4ALL Forum: Opgradere strømforsyning?
Martin
Martin
Attached is the schematic for one channel thanks to Martin.
Will some of you experts on here please take a look at it and see what changes you would make to improve the sound?
I've outlined the changes ole' Kenny does above. Perhaps he's talking about replacing Q1 and Q3 with mosfets? Looks like Q2 and Q4 have been removed.
Also attached is an image of the board after his mods.
Will some of you experts on here please take a look at it and see what changes you would make to improve the sound?
I've outlined the changes ole' Kenny does above. Perhaps he's talking about replacing Q1 and Q3 with mosfets? Looks like Q2 and Q4 have been removed.
Also attached is an image of the board after his mods.
Attachments
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Hi ammel68, got your PM.
I will ask in the thread if he know the types of the semiconductors in his amp after the mod. If you look at the PSU mod it seems that he is removing the regulator and replacing it with some extra resistors and capacitors. I personally would rather keep the regulator and tweak the capacitors. Better yet rebuild the regulator as a shunt type (I like shuntregs).
It seems like he has changed Q3 and Q1, as well as removed Q2 and Q4, removing the symmetrical topology of the input-stage. I think this as well is a fairly drastic mod. It will almost certainly change the sound, but it changes the topology as well, making it essentially another amplifier, from my point of view.
Though I am skeptic, the mods might change the sound for the better, I am not knowledgeable enough to say. The guy in the Danish forum who's had the mods done, is very happy with the sound.
/Martin
I will ask in the thread if he know the types of the semiconductors in his amp after the mod. If you look at the PSU mod it seems that he is removing the regulator and replacing it with some extra resistors and capacitors. I personally would rather keep the regulator and tweak the capacitors. Better yet rebuild the regulator as a shunt type (I like shuntregs).
It seems like he has changed Q3 and Q1, as well as removed Q2 and Q4, removing the symmetrical topology of the input-stage. I think this as well is a fairly drastic mod. It will almost certainly change the sound, but it changes the topology as well, making it essentially another amplifier, from my point of view.
Though I am skeptic, the mods might change the sound for the better, I am not knowledgeable enough to say. The guy in the Danish forum who's had the mods done, is very happy with the sound.
/Martin
I agree, I'm not really interested in the power supply mods. I'm more interested in the changes to the amplifier section itself.
Looks like R14A,B have also been removed. I assume the trimmer pots are there for biasing the mosfet transistors, but not sure.
I'm wondering how similar the modded unit will be to the JC-2 clone on Ebay?
Symmetric Complementary J FET Preamplifier JC 2 KIT | eBay
Looks like R14A,B have also been removed. I assume the trimmer pots are there for biasing the mosfet transistors, but not sure.
I'm wondering how similar the modded unit will be to the JC-2 clone on Ebay?
Symmetric Complementary J FET Preamplifier JC 2 KIT | eBay
Thank you for the additional photos and Aragon schematic. I understand the RL-11 is supposedly very similar to the L10 except for the RL-11 being remote controllable.
The Aragon I have no personal experience with. If someone here has heard both the Aragon and the Acurus, perhaps they can chime in with how the two compare sonically.
The Aragon I have no personal experience with. If someone here has heard both the Aragon and the Acurus, perhaps they can chime in with how the two compare sonically.
Stumbled across this thread kind of late but thought I'd give my .02. I looked over the mods performed by Ken Ealey and I'm not liking what I see there. As others have stated he eliminated the +/- 18 V discrete regulators and is running full rectified voltage to the line stage DC rails. I have worked on a few of these Acurus pre's and the non-regulated voltage is usually around 29 -30 VDC with a good bit of ripple as one would expect. I would say that he is still CRC filtering the rails but now he only has 2 uF film caps where there used to be 1000 uF E-CAPS right after the 10 ohm 2W RC resistors so there is not a lot of storage after those resistors. It also looks like he removed the 10 uF output coupling caps and shorted those from underneath the board. The small electrolytic at the input to the line stage was also added by and I'm assuming it is a non-polar input coupling cap. I can think of no other purpose for it in that location. The Aragon Pre's used an input coupling cap and had the output directly coupled to the line stage. But they also offered a DC offset adjustment to trim the circuit.
Personally I just cannot see that preamp sounding better than the stock unit!
If it were me, I'd develop a current source for the stock complementary diff input. Then I'd turn my attention to the power supply. The stock transformer is only 5 VA and this pre draws about 3 - 4 VA in operation so the transformer is overloaded in my opinion. A 10 VA toroidal will fit nicely, but you will have to be resourceful and build a small bracket. Then a new larger set of main storage caps to replace the 3,300 uF/35v electrolytics (10mm pin spacing snap-in style) and then add a set of wima film bypass caps across the new E-caps on the backside of the board.
If you are feeling really energetic then the cheap metal films can be replaced with RN60D's. It is time consuming, but I've done it on a few of them. You might as well also replace the 1000 uF E-CAPS on the regulated side of the DC rails.
Personally I just cannot see that preamp sounding better than the stock unit!
If it were me, I'd develop a current source for the stock complementary diff input. Then I'd turn my attention to the power supply. The stock transformer is only 5 VA and this pre draws about 3 - 4 VA in operation so the transformer is overloaded in my opinion. A 10 VA toroidal will fit nicely, but you will have to be resourceful and build a small bracket. Then a new larger set of main storage caps to replace the 3,300 uF/35v electrolytics (10mm pin spacing snap-in style) and then add a set of wima film bypass caps across the new E-caps on the backside of the board.
If you are feeling really energetic then the cheap metal films can be replaced with RN60D's. It is time consuming, but I've done it on a few of them. You might as well also replace the 1000 uF E-CAPS on the regulated side of the DC rails.
Personally I just cannot see that preamp sounding better than the stock unit! QUOTE]
I'm the Dane who had the thread on Hifi4All.dk. The Ken Ealey Mod takes the L10 to another level, and deliver far more details in the top, and deep controled bass. - Far deeper then stock.. The soundstage is superb also.
The Hifi4All thread has been deleted, in respect for Kens work.
Hope my English is readable
Thanks// K.Nielsen, Denmark
I certainly hope that the provider of your upgrade services did not request for you to take that thread down. That would be quite sad.
In response, I would post the link to this old Acurus L10 review on The Audio Critic. If you are a big L10 fan then you have probably already seen it at some point in the past. If you read some of the reviews you will notice that the reviewers take the covers off of all the preamp's and go through them with a fine tooth comb, listing the strength's and weaknesses of the circuits in every one of them.
This is a DIYAUDIO site and I/we were just doing the same. Nobody is trying to take Mr. Ealey's business away or purposely disrespect him. However, when you run a business as an audio professional selling an upgrade service then the quality of your work and the upgrades you perform are open for critiquing, like it or not.
I personally see nothing wrong with displaying the interior of any audio gear upgraded by a "High end audio professional". The display of such upgrades should be a testament to their workmanship and draw in even more customers.
I am glad that you are happy with your upgraded L10 and wish you the best with your system.
Actually the thread was closed by admin on my request. I was more then proud to show the circuit in the forum, although the thread wasn't about it at all. Unfortunately when showing the pics, people from all around Denmark started mailing me for a direct copy of the circuit, and that wasn't my intention when starting the thread at all..
The thread was about the PSU.
thanks.
Ken Easley
Hello
I'm glad I stumbled on this thread, I have an Acurus RL-11 and I emailed ken about how long it would take to do the upgrade and his reply was, "I wouldn't recommend you do the upgrade, you probably won't be happy with the results". I don't know if he was having a bad day or misread the tone of my email because I asked how long it would take? Or was it a disgruntled employee? Whatever the case after reading the thread I guess unless you know what you're doing or getting done, be sure you do your research. I enjoy the Acurus i think it sounds amazing stock. But I enjoy the music in my Jeep with the top down! If my acurus ever " breaks" I'd consider upgrades when repairing. So any upgrade suggestions would be more than welcomed. Maybe 5-10 down the road? Who knows
Hello
I'm glad I stumbled on this thread, I have an Acurus RL-11 and I emailed ken about how long it would take to do the upgrade and his reply was, "I wouldn't recommend you do the upgrade, you probably won't be happy with the results". I don't know if he was having a bad day or misread the tone of my email because I asked how long it would take? Or was it a disgruntled employee? Whatever the case after reading the thread I guess unless you know what you're doing or getting done, be sure you do your research. I enjoy the Acurus i think it sounds amazing stock. But I enjoy the music in my Jeep with the top down! If my acurus ever " breaks" I'd consider upgrades when repairing. So any upgrade suggestions would be more than welcomed. Maybe 5-10 down the road? Who knows
At least you got an email reply. That's more than I ever received from ole' Ken.
I sent several emails and never got the first reply. Perhaps he thought I was being a little too "nosey".
At that point, I reached my conclusion about ole' Ken and decided I wouldn't let him ever touch anything of mine. So paying the outrageous price he wants for his "upgrades" was definitely out of the question!
Anyway, I'm really glad Chamberman could shed some light on his "upgrades". If those are indeed some of the things he changes, then these so-called "upgrades" make absolutely NO sense to me, either.
With no coupling caps at the outputs, I would measure the offset at the outputs before connecting it to any power amp.
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