Any Built a Passdiy Amp?

saemark30

These is a website by Nelson Pass with lots of diy amps.
Anyone try one running Polk speakers?

zingo

I have built the B1 preamp and it was a great project. I currently run one of his First Watt designs and it's a great design, but I do not have Polk speakers to try it on. Next time I make it don't to my father-in-laws house, I can try it out on his LSi15s and let you know.

Any of his amps should sound great as they are well designed and single-ended class A, but a concern may be power output driving a few of the less sensitive Polk models.

heiney9

I run a Pass Aleph 30 with Polk SDA 1C's, with no issues. Able to hit 100+dB peaks with 30 wpc. Most of the First Watt stuff is not really designed for conventional muti-driver speaker systems, as they are a speciality amplifier. But any of the Pass Labs stuff should work fine.

H9

saemark30

The Pass Aleph series is one I always wanted to try, but the First Watt F4 or F5 seems to be good for all speakers.
Perhaps biamping is the way to go, best quality without expensive large caps and inductors.

heiney9

The F4 or F5 are certainly better for non-single driver speakers but still wouldn't be good for ALL speakers or even speakers less than 89dB unless you are in a small room and don't listen very loud. The First Watt stuff is designed with a specific type of speaker in mind and while the F4 and F5 and to some extent the new M2 might be able to run some multi-driver speakers, that's just a byproduct of the design.

But then again you haven't even qualified what you are trying to do or what speakers you plan on using or other associated gear. To ask a general, random question like you did, you can't possibly expect to get any type of detailed response or a response that is likely to help, since we have no idea what you are trying to do.

Based on all your posts about upgrading Polk Monitors, I'll run with that since you haven't given any other info. You could get by in a bedroom rig (small room) running Monitor 5's, 7's and probably even 10's with the F4 or F5 as long as you didn't want ear bleeding levels.

I would suggest the Aleph if you are looking at single ended class A Nelson Pass design for your (what I assume) current needs.

H9

saemark30

H9 sorry to be vague or general, but I have multiple speaker systems that include Monitor 7s, 5s and other brands like EPI100 and even an electrostat.
But let's stick to a simple 2 way like Monitor 7.
One plan is to biamp those.
It is in the living room, medium sized and I am running them with EL84 PP tube amp now.
Tubes are expensive, I like a SS amp that is not harsh.

saemark30

H9 my previous DIY experience was building gainclones with LM1875 and LM3886.
I may try biamping with these as proof of concept.

heiney9

saemark30 wrote: »

But let's stick to a simple 2 way like Monitor 7.
One plan is to biamp those.
It is in the living room, medium sized and I am running them with EL84 PP tube amp now.
Tubes are expensive, I like a SS amp that is not harsh.

Tubes are a lot less expensive than real Pass gear and this is coming from someone who has bought a lot of tubes in the past year.

I haven't really followed the Pass DIY community in depth so I'm not sure what is available to build. I still strongly recommend something along the lines of the Aleph rather than the First Watt stuff.

I also have no idea how the DIY stuff compared to the real genuine thing. It's probably just like all DIY hobbies, etc.....it's as good as you are at understanding the concepts and the tools you have to implement the concepts; ie, scope, ability to access and match parts, ability to interpret the concepts, tweak parts and recognize less than optimal issues that arise.

I will say this most of Nelson's stuff is NOT paint by number. He gives you the basics and you as the electronic wiz take it from there. He won't give you a paint by number project and explicitly say "this goes here, that goes there". That's not to say there aren't a hundred hobbiests at a sight like DIYaudio that can't help you or that Nelson himself won't help you.

Soemthing like the B1 buffer is simple enough that not too much needs to be done beyond following the schematic and suggestions. But start adding a power supply and associated parts and it becomes complicated if you don't know the basics and have proper equipment to run tests as you are building.

What I'm getting at is Nelson assumes you are already at a decent level of understanding of the basics, and building an amplifer from scratch with just a schematic isn't for the faint of heart. You need the ability to understand the concepts, source parts, match parts, test parts and then test and calibrate the end product.

I am just stating this generally as I have no idea of your background or knowledge or skill with electronics. I can assume based on your questions in some of your threads, it's pretty basic. Also by the time you get done buying all the proper parts to make the DIY as good as an original, you'll have as much into it as you could probably buy a pristine used piece for.

H9

heiney9

saemark30 wrote: »

H9 my previous DIY experience was building gainclones with LM1875 and LM3886.
I may try biamping with these as proof of concept.

Those are childs play compared to a full blown discrete amplifer. But it certainly is doable as there is a LOT of info out in the DIY community should you get stuck.

I had one of those "chip amps". Peter Daniels boards, Black gates, Caddocks, all the best parts and I never liked the sterile sound of it. Very sterile, 2 dimensional and disconnected. Got rid of it.

H9

Joe08867

heiney9 wrote: »

Those are childs play compared to a full blown discrete amplifer. But it certainly is doable as there is a LOT of info out in the DIY community should you get stuck.

I had one of those "chip amps". Peter Daniels boards, Black gates, Caddocks, all the best parts and I never liked the sterile sound of it. Very sterile, 2 dimensional and disconnected. Got rid of it.

H9

I agree 100%. Chip amps are a neat idea but not very musical in my opinion. They are like H9 said to sterile. and they run out of steam to easy with overly dynamic music.

saemark30

I was thinking to prove a concept of using two LM1875 amps in an EPI100 enclosure and RC passive 1st order filtering.
If you say that is going to be sterile and 2 dimensional then I won't waste my time and money.

heiney9

saemark30 wrote: »

I was thinking to prove a concept of using two LM1875 amps in an EPI100 enclosure and RC passive 1st order filtering.
If you say that is going to be sterile and 2 dimensional then I won't waste my time and money.

Please don't take my experiences and opinions as gospel. I will say if the Pass sound is what you are looking for, the chip amps are far from it, even with the best associated parts.

H9

saemark30

I've gone through Passdiy and read every article. I serviced a few amps including tube ones but never built one from scratch.
I would say my knowledge is intermediate with vintage circuits.
Haven't heard an Aleph but strange as it seems you are suggesting I use two tube amps or just stay with passive crossovers.

heiney9

I didn't say anything about using 2 tube amps. I have no idea what you are running currently, or what you want to replace, or what you want to try and run with what you currently have. You said you have an el84 based tube amp and tubes are expensive. That's all I know about what you are currently running.

See your capacitor thread for a couple questions I asked about bi-amping.

H9

saemark30

I'll see what Nelson Pass will do with biamping, most of the ideals I got from his site.

heiney9

Bi-amping at that level is done with very sophisticated speakers and very sophisticated electronic x-over networks which are then tuned to the room.

There is no "set it and forget it" with true bi-amping. No offense but Nelson wasn't running a pair of Polk Audio Monitor 7's either :biggrin:

H9

saemark30

The Passdiy site is for enthusiasts to learn that high end is need not be sophisticated and have some fun in the process.
I'll let you know if I try biamping this weekend as my plan won't cost much.

heiney9

saemark30 wrote: »

I'll see what Nelson Pass will do with biamping, most of the ideals I got from his site.

Where does he talk about bi-amping specficially? All I see is a 1982 article about Phase coherent x-over networks and a 2004 article about Current Source X-over Filters.

You will not meet a bigger NP fan than myself. Ask anyone here, I practically worship the guy, not literally, but his ideas, concepts and execution.

H9

saemark30

I know on the First Watt site Nelson Pass has plans for a B2, B3, B4 and B5 buffers meant for electronic crossovers.
So for sure he is experimenting with the concept.

heiney9

saemark30 wrote: »

I know on the First Watt site Nelson Pass has plans for a B2, B3, B4 and B5 buffers meant for electronic crossovers.
So for sure he is experimenting with the concept.

Ok, so again I ask you; what electronic x-over are you using? Actually I think this the 3rd time I've asked you. Those buffers are designed to work with an active electronic x-over, not by themselves. I'm not sure I understand why someone wants to go to that expense for a pair of $150 Polk speakers :biggrin:.

But we all have our weaknesses.

H9

saemark30

The M7 used to be $700 speakers up here.
The answer to the electronic crossover is to use passive RC network and buffer that.
I have a few spare amps/receivers.
They will not be at your Aleph 30 level but I think the experience is worth pursuing.

heiney9

the $150 reference is to what they typically go for now used.

Good luck, enjoy you experimenting.

H9

strider

I built an F5 amp from boards purchased on diyAudio. If you've built a gainclone before I'd say you're 90% there in terms of degree of difficulty. Attaching the output devices to the massive heatsinks they spec was intimidating; other then that I'd say the ridiculous amount of info can be overwhelming. It was cheaper to build then the tube preamp I built, both using similar quality parts.

Big Dawg

I'm pretty sure I read where Face had built one at some point.

Big Dawg

Big Dawg wrote: »

I'm pretty sure I read where Face had built one at some point.

Okay, my bad. He sold one, but didn't build it:

http://www.polkaudio.com/forums/showthread.php?t=95919&highlight=pass

CoolJazz

I'm helping a friend build a F4 which I'm also collecting the parts for at the same time. These are with the boards available through the DIYAudio site. Plenty information there on what's needed...just takes a while to read the long threads! Don't need to build another F4 right away, as I've already picked up two DIY F4's that I've been playing with. I've been running them for bass below 200hz as mono-blocks which with the about 3 ohm load I'm presenting them with, I would get towards a 100 watts...way beyond what's needed. But they've been a very good experience sonically and use wise.

Also using an original FW F1 for full range drivers about 200hz. Superb should cover the experience with it.

Building one yourself requires some metal work along with the electronics and the physicals of contruction, which specifically needs attention to the heatsinking as a priority! But the power supply is pretty straight forward and the amplifier boards aren't complicated or too tough.

I would think if you can do the Gainclone's, then it's not too too big of step to build any of the designs that you can find the boards for, the important output devices and then the PS parts and the chassis. To avoid getting too complicated on a first step up build, I'd suggest doing it pretty much as listed out and don't try to get fancy and do something off the beaten path!


Oh, and in the First Watt line he's already got the one active crossover for OB use out now and the similar one for more typical bi-amped setups to be out soon.

CJ

heiney9

So what do you guys do to test these DIY amps? You just solder the parts in and hook up speakers? I would think at minimum you'd need a scope and DVM and the ability to properly use both. Then again some of Nelson's designs have all the constraints constant as set by the parts choice. IE; there is no "dialing them in", so to speak.

H9

strider

I got away with one DVM when I built mine, two would have been much easier though. You need it to set the DC offset of each channel. I suppose there are plenty of things you could measure with a scope, but it isn't a necessity.

CoolJazz

It's best to first make sure the PS output is clean and then, at the end of a build, the amp stage to make sure no kind of oscillation is going on. That would be the value in a scope. But if you've used the boards and used the suggested parts, it's not likely that your going to have any problems.

I've got all kinds of analyzers etc. The prebuilt DIY's I bought, I looked of the physicals and didn't have any concerns and didn't check them. The original unit, I changed the transformer and the filter caps and as straight forward as that is, didn't do more than peak at the output of the supply with a scope. On the one my buddy is building, I'll check it out thoroughly including harmonics and power at clipping and so forth. As of a couple weeks ago, he was about ready to mount the PCB's and wire.

CJ