DIY amp for B&W 805's?
Hi all,
I was just able to finagle my way into a pair of B&W 805's at a great price (It's good to have worked for a dealer!) - I was expecting to get some Rotel equipment to pair them with...but I realistically can't afford $3000 worth of equipment right now. So, my mind got to wandering into the DIY realm. I'm an electrical engineer fresh out of college, with a good amount of high voltage experience and a healthy amount of audio-specific experience too (fixing some old tube stuff, making a great sounding SS headphone amp...I'll likely make another post concerning THAT later).
Anyway I'd like to make myself a good sounding amp to do these speakers justice...I don't think my kenwood HT receiver is going to cut it for very long! I'm not sure if I just want to build a power amp and use the kenwood for a pre for now...or just go for an integrated. Or a separate pre/power. The 805's are not particularly efficient, weighing in at 88 dB, so I would imagine I'd need a design with a fair amount of good power. Maybe somewhere in the realm of 100W? It seems like there are so many good designs out there, it's a bit overwhelming trying to fish through everything.
Does anyone have any ideas/thoughts/suggestions/incoherent ramblings? Any and all help would be much appreciated.
Thanks much,
Bob
Hi all,
I was just able to finagle my way into a pair of B&W 805's at a great price (It's good to have worked for a dealer!) - I was expecting to get some Rotel equipment to pair them with...but I realistically can't afford $3000 worth of equipment right now. So, my mind got to wandering into the DIY realm. I'm an electrical engineer fresh out of college, with a good amount of high voltage experience and a healthy amount of audio-specific experience too (fixing some old tube stuff, making a great sounding SS headphone amp...I'll likely make another post concerning THAT later).
Anyway I'd like to make myself a good sounding amp to do these speakers justice...I don't think my kenwood HT receiver is going to cut it for very long! I'm not sure if I just want to build a power amp and use the kenwood for a pre for now...or just go for an integrated. Or a separate pre/power. The 805's are not particularly efficient, weighing in at 88 dB, so I would imagine I'd need a design with a fair amount of good power. Maybe somewhere in the realm of 100W? It seems like there are so many good designs out there, it's a bit overwhelming trying to fish through everything.
Does anyone have any ideas/thoughts/suggestions/incoherent ramblings? Any and all help would be much appreciated.
Thanks much,
Bob
Without hesitation....
http://www.diyaudio.com/forums/showthread.php?s=&threadid=54571
Edit: I owned the 805 matrix version. They worked well together.
I then recycled the 6.5" mid added the Scan Speak 9900 Revelator tweeters and a LEAP crossover from Meniscus in new enclosures.. Mauro's amp still did it justice.
Only reason I recycled the 805's was because the tweeter pods finally broke after repeated knock overs by children.. What can ya do..
http://www.diyaudio.com/forums/showthread.php?s=&threadid=54571
Edit: I owned the 805 matrix version. They worked well together.
I then recycled the 6.5" mid added the Scan Speak 9900 Revelator tweeters and a LEAP crossover from Meniscus in new enclosures.. Mauro's amp still did it justice.
Only reason I recycled the 805's was because the tweeter pods finally broke after repeated knock overs by children.. What can ya do..
This is a very good amp:
http://users.ece.gatech.edu/~mleach/lowtim/
I have build it and I'm very satisfied.
http://users.ece.gatech.edu/~mleach/lowtim/
I have build it and I'm very satisfied.
Yeah...I think I agree with this. I'm certainly open to all ideas right now, but my gut has been telling me that a chip-amp might not offer all the quality I'm looking for. Then again, I've never actually heard one so I could be dead wrong!
As for that leach amp...it's very well documented! I'm going to have to sit down with a cup of coffee tomorrow (or maybe even a beer...it's friday, after all!) and give that site a more thorough read. And actually, a quick search for "Leach" on this site gives quite a staggering set of results. Looks like I have some reading ahead of me!
I do like having options though, any other ideas out there? Thoughts on the Leach?
Mauro's is not a chip amp.
But then again some people know all the answers and have deep pockets.
To also represent the other side, I have four UcD 180AD's sitting idle in a chassis I have not been able to complete as of yet. I can't comment on thier performance with the 805's but you won't find an easier amp to construct that will sound as good.
Jens did a small (6 trannies) and large (10 trannies) version of the Leech amp. Very impressive PCB's if they are still available.
But then again some people know all the answers and have deep pockets.
To also represent the other side, I have four UcD 180AD's sitting idle in a chassis I have not been able to complete as of yet. I can't comment on thier performance with the 805's but you won't find an easier amp to construct that will sound as good.
Jens did a small (6 trannies) and large (10 trannies) version of the Leech amp. Very impressive PCB's if they are still available.
My mistake, 4 transistors on the small. Still would be a good match for the 805's.
http://www.diyaudio.com/forums/showthread.php?postid=585615#post585615
http://www.diyaudio.com/forums/showthread.php?postid=585615#post585615
Haha, I hear ya about the tweeters on the Matrix line, Troy...I just sold my Matrix 804's (to raise money for the new 805's), on which I had to replace one of those tweeter casings. I *am* a bit concerned that the Nautilus tweeter seems rather more fragile...
So, just out of curiosity, what makes mauro's design not a chip amp? Both gain stages are built around ICs...? Not to sound ignorant or anything, I'm just new here.
I also took a gander at Jens's thread...very nice PCB's indeed, but I think that ship may have sailed. I've got no real problem rolling my own though; my new job got me a seat of Altium, and there are plenty of PCB houses with reasonable prices on low volume prototype boards. We've actually also got an LPKF circuit board prototyping machine here that I have access to as well - that might be interesting to play around with.
As for the lower-power version - I know the 805's aren't big speakers but I've heard them paired wonderfully with a 130wpc Rotel amp. Part of me says "better to have extra power, gotta be able to keep up with big transients" - while part of me says "the amp isn't going to sound as good as it can until it's cranked a good bit." Decisions, decisions...
So, just out of curiosity, what makes mauro's design not a chip amp? Both gain stages are built around ICs...? Not to sound ignorant or anything, I'm just new here.
I also took a gander at Jens's thread...very nice PCB's indeed, but I think that ship may have sailed. I've got no real problem rolling my own though; my new job got me a seat of Altium, and there are plenty of PCB houses with reasonable prices on low volume prototype boards. We've actually also got an LPKF circuit board prototyping machine here that I have access to as well - that might be interesting to play around with.
As for the lower-power version - I know the 805's aren't big speakers but I've heard them paired wonderfully with a 130wpc Rotel amp. Part of me says "better to have extra power, gotta be able to keep up with big transients" - while part of me says "the amp isn't going to sound as good as it can until it's cranked a good bit." Decisions, decisions...
orangeshasta said:
I had the Bryston 3B and the Jeff Rowland Model 2 on them. The Bryston / Bi-wire Kimber 4TC/ 805 combo was KILLER. It flat out beat many more costly systems.
Mauro's amp uses the LM3886 as a current pump. The actual amplification "I BELIEVE" was done in the op-amp. It was a closed loop design that made both units "functionally" one. It really sounded great for the money rivaling the big name brands (ML, Krell, JRDG, Audio Research) and bettering the Rotel / Adcom / Parasound types by far. But yes, I think he went direct sales only now.
"If it were me", or "in MY opinion" I'd either do the UcD180x or Leech in mono blocks. I lean to the UcD for the energy efficiency (thinking of the children) and "latest greatest" technology. BUT I have not heard the Leech nor UcD myself.
Hi,
the Leach is very good but not up with the best.
I think the B&Ws deserve nothing less than a Leach.
What are the impedance and phase curves like for the 805?
I think they are a pretty severe load on any amp.
The Leach could be your starter and when you start looking for more, then a second pair of amps could be added to get the best out of the mid or treble drivers.
Go for a pair of monoblocks as your first project and locate each right beside each speaker with very short speaker cables. Mono are easiest to build, but do cost a little more for the extra transformer and chassis.
The standard Leach output stage is 2pair of 250W devices, the clone is 3pair of plastic packaged devices (I used MJL4281/4301 230W and got 170W from 40Vac 1kVA transformers). I suggest going for a 3pair output stage to maintain good current delivery into low impedance loads (if the 805 is as bad as I recall).
the Leach is very good but not up with the best.
I think the B&Ws deserve nothing less than a Leach.
What are the impedance and phase curves like for the 805?
I think they are a pretty severe load on any amp.
The Leach could be your starter and when you start looking for more, then a second pair of amps could be added to get the best out of the mid or treble drivers.
Go for a pair of monoblocks as your first project and locate each right beside each speaker with very short speaker cables. Mono are easiest to build, but do cost a little more for the extra transformer and chassis.
The standard Leach output stage is 2pair of 250W devices, the clone is 3pair of plastic packaged devices (I used MJL4281/4301 230W and got 170W from 40Vac 1kVA transformers). I suggest going for a 3pair output stage to maintain good current delivery into low impedance loads (if the 805 is as bad as I recall).
My_Ref
The My_Ref is built with IC's and chip amps. But has almost no relationship with the National datasheet circuits. Even the buffered designs.
The input device provides the voltage gain and the LM3886 provides the current gain. There is an extremely complex current feedback network to allow this to happen.
The results are much better than what I expected. I am confident that a My_Ref would drive the 805's just fine. I used one for a short period to drive my 801 Series II's and the combo worked. The 801's are a much more demanding load compared to the 805's.
I would not recommend a My_Ref to control 801's or even 802's. It should be fine for the B&W's with smaller woofers.
There are lots of good diy designs available. SKA, ASKA from Oz, the TP bridged design, SymAsym, and some of the Aleph clones. Any of the above should work fine.
Two of the amps with the most vocal support are the ASKA and SymAsym. Both are highly recommended by builders. They sound very different, the ASKA is warm by design. The SymAsym is very revealing and clear. Apples and oranges.
George
The My_Ref is built with IC's and chip amps. But has almost no relationship with the National datasheet circuits. Even the buffered designs.
The input device provides the voltage gain and the LM3886 provides the current gain. There is an extremely complex current feedback network to allow this to happen.
The results are much better than what I expected. I am confident that a My_Ref would drive the 805's just fine. I used one for a short period to drive my 801 Series II's and the combo worked. The 801's are a much more demanding load compared to the 805's.
I would not recommend a My_Ref to control 801's or even 802's. It should be fine for the B&W's with smaller woofers.
There are lots of good diy designs available. SKA, ASKA from Oz, the TP bridged design, SymAsym, and some of the Aleph clones. Any of the above should work fine.
Two of the amps with the most vocal support are the ASKA and SymAsym. Both are highly recommended by builders. They sound very different, the ASKA is warm by design. The SymAsym is very revealing and clear. Apples and oranges.
George
So that's two votes so far for running the Leach as a pair of monoblocks. I always thought that maybe this was excessive (although, admittedly, REALLY cool looking) - what would be the actual sound benefits of separating them out into two boxes? Just the dedicated power supplies?
As for the Leach clone with 3pr output devices, I assume we're talking about the one at Delta Audio? (http://www.delta-audio.com/Leach-Clone-6.htm) I like those TO-247 style cases better, why make extra wires off the PCB if you don't have to? He's got a design with 5pr as well, would I be better off just going all out and doing that? I've heard the same thing about the tricky impedance of the 805's (dropping to almost 4 ohms at times), but I wasn't able to find a graph or anything.
Considering the other designs suggested by Panelhead - I think a clear, revealing amp is necessary to make the 805's shine. I've demo'd them with a bunch of different amp/preamp combos (like I said, it's great to work for a dealer) and I always thought the least colored amps were the ones to make them sparkle. How does the SymAsym compare to the Leach in terms of sound?
I've gotta say, this is pretty weird - trying to decide on an amp without ever having heard it...I guess that's the excitement of DIY though!
As for the Leach clone with 3pr output devices, I assume we're talking about the one at Delta Audio? (http://www.delta-audio.com/Leach-Clone-6.htm) I like those TO-247 style cases better, why make extra wires off the PCB if you don't have to? He's got a design with 5pr as well, would I be better off just going all out and doing that? I've heard the same thing about the tricky impedance of the 805's (dropping to almost 4 ohms at times), but I wasn't able to find a graph or anything.
Considering the other designs suggested by Panelhead - I think a clear, revealing amp is necessary to make the 805's shine. I've demo'd them with a bunch of different amp/preamp combos (like I said, it's great to work for a dealer) and I always thought the least colored amps were the ones to make them sparkle. How does the SymAsym compare to the Leach in terms of sound?
I've gotta say, this is pretty weird - trying to decide on an amp without ever having heard it...I guess that's the excitement of DIY though!
I have a pair of 804 and a pair of CDM1.
Both pairs I drive using an Xed version of the Linsley Hood Class A for more than a year, the 804s in 100W Class A with MOSFETs, and the CDM1s using 25W Class A with bipolars (MJ21194).
Won't want anything else, at least not for now.
The basic MOSFET circuit you can find in the PLH thread in the Pass forum.
http://www.diyaudio.com/forums/showthread.php?postid=722428#post722428
The bipolar in the JLH Class A thread.
http://www.diyaudio.com/forums/showthread.php?s=&postid=942753&highlight=#post942753
You should only use the circuits as a reference and adjust the values to suit your configuration. If you just want to used a well proven circuit, go to Geoff's website and build the updated Linsley Hodd as published there.
http://www.tcaas.btinternet.co.uk/jlhupdate.htm
Only my personal opinion.
Patrick
Both pairs I drive using an Xed version of the Linsley Hood Class A for more than a year, the 804s in 100W Class A with MOSFETs, and the CDM1s using 25W Class A with bipolars (MJ21194).
Won't want anything else, at least not for now.
The basic MOSFET circuit you can find in the PLH thread in the Pass forum.
http://www.diyaudio.com/forums/showthread.php?postid=722428#post722428
The bipolar in the JLH Class A thread.
http://www.diyaudio.com/forums/showthread.php?s=&postid=942753&highlight=#post942753
You should only use the circuits as a reference and adjust the values to suit your configuration. If you just want to used a well proven circuit, go to Geoff's website and build the updated Linsley Hodd as published there.
http://www.tcaas.btinternet.co.uk/jlhupdate.htm
Only my personal opinion.
Patrick
"....what would be the actual sound benefits of separating them out into two boxes?... "
In MY opinion the best reason is shorter speaker cables.
As for Class A, I started the Pass Mini-A / A30 and the Krell KSA-50 Klone but did not get to finish those (domestic issues).
PS, Mark A. Gulbrandsen still has some KSA-50 clone PCB's available, and I'm sure someone has a pair of the Mini-A pcb's you could pick up.
In MY opinion the best reason is shorter speaker cables.
As for Class A, I started the Pass Mini-A / A30 and the Krell KSA-50 Klone but did not get to finish those (domestic issues).
PS, Mark A. Gulbrandsen still has some KSA-50 clone PCB's available, and I'm sure someone has a pair of the Mini-A pcb's you could pick up.
Ditto, I 'm also a My_ref owner, and it is quite beatable when you move on to solidstate... however, total build tends to be much less expensive when considering heatsinks etc...
I can realy reccommend the DX amp found in the WWW link below my post... its is easy to build... component cost is low, and is standard config will do about 50W into 8 ohms, and 100W into 4.
And sound is awesome all considered...
Also has an actively followed thread here for user support.
I can realy reccommend the DX amp found in the WWW link below my post... its is easy to build... component cost is low, and is standard config will do about 50W into 8 ohms, and 100W into 4.
And sound is awesome all considered...
Also has an actively followed thread here for user support.
Okay, but then we have longer interconnects. Wouldn't it be more beneficial to have a shorter length of the interconnect cables which have a smaller signal going through them, so as to be less susceptible to noise?
That hood amp looks intriguing as well...seems very simple, which in my experience (limited, admittedly) is generally a good thing. Nice low component count. The KSA-50 Klone is certainly another choice too, I've heard great things about the original.
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