Advice on eBay Amp Modules and PSU's please.

[tubehunter]

Sound great for the price.

Happy Days

http://www.ebay.co.uk/itm/2717307434...%3AMEBIDX%3AIT

[Qwin]

Thanks for putting this in a language I can understand .

Your welcome Darren - I've had another look at the board you were considering and I can see there is an on board rectifier next to the +/- 12vac inputs on the centre of the upper edge of the PCB, so that makes sense. There is not enough information supplied for my liking, in terms of how much current has to be on tap with your power supplies etc. I think leaving this one alone is a wise move.

The Connexelectronic stuff is not very good in this respect either, documentation is non existent. I am looking at putting their IRS400SMPS modules for bass duties and their LM3886SMPS (Gainclone) modules for mid and tweeter on my active Yamaha NS-1000m speakers. I contacted them and they said this combination was ideal for a three way active set up and could be built into the speaker cabinet if I wished. I have one of the LM3886SMPS modules on test at the moment, it seems well made, has lots of safety devices built in, like DC detection/shut down on the speaker outputs, short circuit protection, under/over voltage protection etc. It also came with a full set of leads to plug into the PCB sockets, so I just had to connect these and I was in business. It gives out the tiniest amount of hum if you put your ear to the speakers, but this is a lot less than my Nakamichi AV Power amp, so nothing to worry about.

Quite a few people have built power amps using Hypex modules and used Connexelectronic SMPS's to power them, in preference to Hypex's own, the Hypex SMPS are very good but expensive, if they are being used to supply top notch and quite expensive modules like these, they must be pretty good SMPS's.

I think a pair of these amplifier modules with on board SMPS would get the job done for you.

[DarrenHW]

Sound great for the price.

Happy Days

http://www.ebay.co.uk/itm/2717307434...%3AMEBIDX%3AIT

Thanks for the suggestion Duncan, I'm not sure it would have enough welly for the main sub's but they do look like a potential bargain for the 8" drivers I have, do you know if it's 200w into 4 or 8ohm?

P.S. When did you stop hating OP Amps?

Your welcome Darren - I've had another look at the board you were considering and I can see there is an on board rectifier next to the +/- 12vac inputs on the centre of the upper edge of the PCB, so that makes sense. There is not enough information supplied for my liking, in terms of how much current has to be on tap with your power supplies etc. I think leaving this one alone is a wise move.

The Connexelectronic stuff is not very good in this respect either, documentation is non existent. I am looking at putting their IRS400SMPS modules for bass duties and their LM3886SMPS (Gainclone) modules for mid and tweeter on my active Yamaha NS-1000m speakers. I contacted them and they said this combination was ideal for a three way active set up and could be built into the speaker cabinet if I wished.

None of the eBay modules seem to have great documentation, I guess it's not a problem if you're familiar with amplifier design (which I suppose is the market their aimed at) but it would be a lot easier to make a decission if proper documentation was available. One of the attractions of the LJM amps is that they have an account on DIYAudio, I think the Connexelectronics account has been banned.

I have one of the LM3886SMPS modules on test at the moment, it seems well made, has lots of safety devices built in, like DC detection/shut down on the speaker outputs, short circuit protection, under/over voltage protection etc. It also came with a full set of leads to plug into the PCB sockets, so I just had to connect these and I was in business. It gives out the tiniest amount of hum if you put your ear to the speakers, but this is a lot less than my Nakamichi AV Power amp, so nothing to worry about.

The safety features are a plus, although I've read a couple of posts that suggest some onboard safety devices are useless (not necessarily aimed at Connex). What's your opinion on these, have you had a chance to test?

Have you had a chance to listen to the LM3886SMPS, if so how would you compare it to the Nak?

Quite a few people have built power amps using Hypex modules and used Connexelectronic SMPS's to power them, in preference to Hypex's own, the Hypex SMPS are very good but expensive, if they are being used to supply top notch and quite expensive modules like these, they must be pretty good SMPS's.

I think a pair of these amplifier modules with on board SMPS would get the job done for you.

It was the Hypex modules that first opened my eye's to this. Zu Audio use a Hypex UcD 400 and the Lab12 in their sub's and of all the commercial sub's I've looked at this had the greatest appeal. I agree Hypex amps have a good reputation so using them in conjunction with Connex SMPS's speaks volumes. I take it you have no concerns using a SMPS?

[DarrenHW]

I think a pair of these amplifier modules with on board SMPS would get the job done for you.

I've just ordered a pair.

[Qwin]

Hi Darren
I've no doubt that the Hypex SMPS are better, they are supposed to run absolutely silent, but the Connex. are not too far behind, if I just needed one I would buy Hypex, but as I need several or with them on board the amp modules, it starts to mount up. I've not tested the safety features so don't know how effective they are.

I've been listening a lot to the LM3886smps module, as two channels of midrange, with the other four channels being covered by the Nakamichi on the 3 way active Yamaha's. They hold their own and I would say each sounds slightly different as opposed to one being better. I like the way the Gainclone does the midrange and vocals a lot. For the last few days I have been listening to the Gainclone module as a stand alone 2 channel power amp, being fed from my new Pro-Ject Pre Box RS and using a pair of old stand mount Tannoy M20 Mercury speakers and it sounds damn good. Got JazzFM on in the background as a freesat optical digital signal fed into my DAC and the piano solo is sounding so clear and tonally accurate.
I really rate this module, a stereo amp and power supply on a 100mm square board and it trounces something like a Quad 306 for transparency, realism and clean bass.
As Jez Arkless put it recently "Shockingly good for a "car radio chip" are those LM3886 They are a prime example of how sometimes in this game one can get lets say 85% of the performance that it's even possible to get for little money.... but then to get another 10% you need to add at least a nought to the cost"
Rod Elliot (ESP) described them as "Audiophile items with a caveat", that being you don't drive them to close to clipping, as the protection circuitry kicks in early and adds noise as it approaches activation.
Using SMPS over a linear supply is controversial, but I read a couple of threads from Gainclone builders who had tried just about every option and combination available and thought they sounded better using a SMPS.
Gainclone Chip Amps and class D for bass, using SMPS's offers a compact solution that is light weight and generates little heat, what's not to like.

Liking it a lot in fact, no hesitation in using LM3886SMPS to drive mid and tweeters on the Yamaha's, if the IRS400SMPS bass module sounds as good as the Nakamichi I will be well pleased. Be interested in your impression of the more powerful IRS500SMPS - If that's what you ordered?

[DarrenHW]

Hi Ken,

Yes, I ordered 2 x IRS500SMPS.

I know what your saying about the cost multiplier, I'm going to attempt to integrate 6 subs, front left, front right (both 12" sealed ~100 litre), rear left, rear right (both 8" sealed ~ 25 litre), centre (I'm thinking 10" sealed ~ 50 litre) and a dedicated AV sub (minimum 12" ported ~100 litre). This may sound ridiculous but I have had nothing but positive results adding a sub to these channels, obviously the frequency range is increased and bass response is improved but the biggest benefit is the "bed" that the bass provides which the other frequencies seem to "ride" on, improving the surround illusion. I don't know how well this is going to work, it wasn't my original plan but the more I've read the more compelling the argument is for one sub per channel. I should add at this point that I am probably what is referred to as a "bass head" primarily due to my exposure to Marco's Tannoys!

I know the Gainclone's have a strong following and they seem ideal for your application. When researching the above Peerless drivers I came across this http://mjanyst.weebly.com/audio.html where they have been used to power the subs!?! I agree the choice of a SMPS for audio is controversial (this was the concern I had when starting this thread, now I'm really glad I did!) but it's encouraging that they are considered by some to be the best option. I plan on strapping the amp / psu to the exterior of my subs so low heat, weight and size are all desirable attributes for me too.

I will report back with my impressions of the IRS500SMPS but this will not be in comparison to the Nak as I do not use it for subwoofer duties. A couple of months ago when the amp plate in my existing sub died I borrowed a REL Seri S5 which opened my eyes to what a sealed sub could do. Since the 44's made themselves at home in my lounge I've fancied trying a sealed sub and I'm very glad I did, integration with the 44's was good and after a little tweaking the sub audibly disappeared. I was offered a very good deal (for a sub with a RRP of £1600) but there were two factors that dissuaded me from buying it; i, it didn't go low enough for AV meaning I'd have to buy another ported sub, and, ii, it lacked a little slam compared to the 44's, rightly or wrongly I put this down to the ABR. With the expense I'd have gone too if I bought the Rel and added a ported sub I decided the DIY route would be worth investigating. My current objective is to build two sealed subs as helpers for the 44's with the primary focus being music and the benchmark being the Rel. Hopefully I can drag Marco round to help me setup the subs and I'm sure he'll be far more capable of reporting back on the sonic attributes of the amps than me.

[Qwin]

Sealed Woofer/Sub the more I hear this type of speaker the more I like it.

I recently came across an article saying the bass on the Yam NS-1000m didn't go that deep and started to roll off at about 50Hz. The Celestion 66's start to roll off closer to 60Hz, so why do both these speakers sound so full bodied. Its because they both are good in the upper bass, which is most of what we hear in music tracks, also the bass on sealed or ABR systems rolls off a lot slower than ported so more of the deeper bass is still at an audible level. In this respect the F3 (Minus 3dB) quoted figure can be misleading when comparing ported against sealed.
I researched the figures for the Yamaha's and Troels Gravesen confirmed this 50Hz roll off, both in simulation using T&S parameters for the bass driver in its stock enclosure volume and also with actual measured response of the speakers.
I went to the Wigwam Show a couple of weeks back and for me, one of the stand out moments was listening to a DIY lash up, the guy (Looper) is very good at programming and had written his own FIR filters for a DSP 3 way active system. He had used a 12" driver in a 90L sealed cabinet which he happened to have. Me and Gordon (Halfway Tree) just looked at each other, this was some of the best bass in the show, tight deep and tuneful. We asked what drivers he had used, the bass were Skytronic 902-222 he said they were 12" car speakers meant for ported boom boxes, but when he did the T&S numbers they were better suited to sealed cabinets of around 100L 120L being optimum. When he said he bought the pair, new off ebay for £47 I was gob smacked. I may buy some of these drivers they calculate as an F3 of about 32Hz in a 100L sealed cabinet. Like I say the sound stopped me in my tracks for the shear quality of the bass.

[walpurgis]

An ABR equipped speaker is a reflex type. The ABR taking the place of the bass port. They should not be regarded as a sealed, 'infinite baffle' speaker. Their characteristics are not the same and the bass curve using an ABR will be much the same as that produced using a reflex port, assuming the speakers are otherwise similar and similarly tuned.

[Qwin]

Because of the increased loading/damping compared to ported, I have always found ABR to react more like a sealed cabinet, but it is more like a halfway house I suppose. Like sealed I found ABR has less interaction with the room. The bass curve on Celestion 66's (ABR) is more like sealed than ported and is what triggered my comment. Most reflex designs drop off a cliff after the initial roll off, once port velocity has dropped they contribute zero to the output so the drop off is rapid. With infinite baffle and to a lesser degree ABR, they tend to roll off more gradually, these are generalised observations and there are always going to be exceptions, but that's how it comes across to me.

[walpurgis]

Posted by me three years ago.

http://theartofsound.net/forum/showt...s-folks/page42