Gainclone heaven ?

[Nick]

I know quite a lot of people on the forum are using Gainclones and high efficiency speakers so I thought I’d mention an experience I had setting up Gainclone amps this week end.

Some time ago when I built my amp I decided to build it with 4 Gainclone amp modules but I never go round to using all of these and have been driving my speakers with only two of the modules. The idea of having 4 modules was that I could configure the amp as parallel paired amps, bridged pairs, or run Bi-Amped into individual speaker drivers.

I finally go round to getting some extra speaker cable this week-end so I could Bi-Wire the speakers, then I set the outputs of the amp up to Bi-Amp the speakers using one Gainclone module per speaker driver (In fact the set up is really Tri-Amped because Avantguards have active bass already). Anyway the results were really very eye opening. Lots of "problems" that I had assumed were PC, OS, XX software or DAC related were just fixed. 

The experience made me rethink what I was doing to tune my system  Before this I was assuming my focus should be in the PC and DAC. It turns out they were doing a pretty fantastic job all along and the Amps were the place to be looking. I hadn’t bothered with the amp side of things because general wisdom is that 1 gain clone per channel is great for high efficiency speakers that present an easy load. Now I’m really glad I spent the small amount of extra time and money needed to put the extra gain clone modules in to the amps. I would certainly recommend thinking about Bi-Amping if you are already using Gainclones.

The only downside is this could lead me down an expensive path that I hadn't intended to take. I always said to myself I would not go down the path of an XX software cross-over and a multi channel Phasure NOS1 when (if ?) Peter decides to develop this. With the Tri- Amping now in place and working so well, suddenly software crossovers look like the next logical step. Better start saving now ! 

Nick.

[PeterSt]

Nick, hi there !

What I wonder in the mean time, is how you set this up really. To make clear what I mean, I better explain how I do it (not really my "invention" btw) :

So, I have (per channel) one GainClone and it's for the mid-high. In parallel output, that GainClone goes into the second amp which is for the Bass driver. However, in between there ("line"), there's the crossover for the Bass. Here too, the bass part can just as well considered to be "active", although physically the both amps are in one chassis, and are both GainClones. But, I see no difference when one of these would have been "actively" in the speakers cabinet, further fed exactly the same. So, bi-amp allright, and no "tri" as seems to be needed in your setup.

Notice that the first amp acts as a preamp for the second one, and will determine the sound largely. Also, think something like 27dB gain into 27dB gain but with a (crossover and) volume in between it. The latter is part of the crossover just the same (and I assume that you know how this works).
Before my crossover was passive, but today it is an active one (also not my idea, and IIRC under 150 euros for two channels). Seems to work as good, but with many more possibilities. 9 dials on it, but 5 are unused.

So, am I using one GainCone too few, or are you using one too much ?
Btw, I have lots of headroom left for the bass, and the mid-high is at -15dB most.

Let me know what you think,
Peter


PS: Which all doesn't prevent me of looking forward to software XOvers.

[Nick]

Peter hi,

If I understand your post I think your speakers may have two driver channels a combined High/Mid and separate Bass (?), whereas I have three driver channels High, Mid and Bass.

In my setup, working forward from the each Gainclone module’s output in my amplifier towards the speaker driver, each speaker channel looks like this;

Horn loaded Tweeter

Gain Clone Module 1 > Bi Wire speaker cable 1 > Tweeter Cross Over > Tweeter Driver.

Bi Polar reflex Bass

Gain Clone Module 1 > Bi Wire speaker cable 1 > “High Level” feed to Active Bass amp within the speaker via its high level input, the speaker’s internal base amp has volume control and roll off pots to trim its Bass integration with the other drivers > Bass Drivers.

So yes as you say this Gain Clone Module 1 does two jobs, first it drives Tweeter and second it acts as a "pre amp" for the active base amp within the speaker. The good thing here is that speakers internal bass amp only present a load on the K Ohm range so Gainclone module 1 only really has to “drive” the tweeter.

Horn loaded Mid Range

Gain Clone Module 2 > Bi Wire Speaker cable 2 > Direct connection to mid-rage horn driver without any cross over.


I build the Gainclone amp with two modules per channel as left / right mono blocks electrically going back as far as to the amp’s power cable but everything is in one case. There are two Gainclones modules per channel fed by a separate 300Va R-Core transformer and rectifier. (As an upgrade I guess I might gain an improvement by adding a couple more transformers and rectifiers to get mono blocks on all 4 Gainclones modules back to the power cord ?)

As you say my setup is not quite true Tri-amping because the speakers active bass amp is fed by Gainclone module 1 (above). If I were to go down the active software cross-over route I would tap in to the existing active base amp within the speaker cabinets by passing the internal bass volume control and cross over to drive the amp it at line level from a DAC output.

[PeterSt]

Ah, ok. I never understood you had three drivers in there. Sorry.

But now I think of it ... what I also have, is the output of the second amp (the bass amp) (besides from going to the bass driver), going to the high (LS) input of the sub woofer - which is active. This itself having a(n active) crossover again.

In the end it all turns out to be pretty much the same I think. So, I don't have separate amps for mid and high, but at the low(er) end I have.
GainClone1 -> LineFilter -> Gainclone2 -> SubWFilter->SubWAmp.

[Nick]

Peter,

This is interesting, I would be tempted to bay pass the SubWFilter, but you have me wondering what the benefit is of the stacked Gainclones ?

GainClone1 -> LineFilter -> Gainclone2 -> SubWFilter->SubWAmp.

Gainclone 2 only sees the bass spectrum passed by the Line Corssover filter which prevents it having to process higher frequencies ?

Gainclone 2 maybe has a PSU feeding it that is optimised for good low frequency response (eg more capacitance or something) ?

The DAC driving the input sees ~20k Ohm load rather than two gainclones in parallel giving say a ~10k Ohm load (but the output impedance of the NOS1 is easily low enought to drive two or more Gainclones).

Some quality of the high gain from having three amp stages ? but I am not sure this in itself would be doing anything. Perhaps you need this to keep up with the 115db response of your Mid High driver ?
Any insights ?

Regards,

Nick.

[AUDIODIDAKT]

Hmm. GainClone,

Did some reading, looks nice......

Because i have almost all parts here, 4x psu amplimo 35v, 4x power-delay circuits.
So the only things i need, are some cooling parts and some decent caps, opamps and some other cheap parts.
ok...... I'am in.....

I have to read some more, but if you have some proper links, these are always welcome.

PS: if you want to try using software x-overs, do you need for eg. a second juli@ ? or......?
PPS: if you dont use software x-overs but just a passive x-over and use bi-amping, how would you connect the interlink to the amp
as 1 cable input and internally y wired to the inputs of the 2xamps per ch. ?


Roy

[Nick]

Hmm. GainClone,

Did some reading, looks nice......

Because i have almost all parts here, 4x psu amplimo 35v, 4x power-delay circuits.
So the only things i need, are some cooling parts and some decent caps, opamps and some other cheap parts.
ok...... I'am in.....

I have to read some more, but if you have some proper links, these are always welcome.

PS: if you want to try using software x-overs, do you need for eg. a second juli@ ? or......?
PPS: if you dont use software x-overs but just a passive x-over and use bi-amping, how would you connect the interlink to the amp
as 1 cable input and internally y wired to the inputs of the 2xamps per ch. ?


Roy

Hi Roy,

My first question would be how efficient are your speakers ? People do use Gainlones with moderately efficient speakers but they give about 35 ish watts which only goes so far I guess. I think Peter St and I have both found you can get a long way using them with efficient speakers and easy load characteristics.

For my amp I bought a couple of Peter Danial’s premium kits giving me 4 Gainclone modules. I replaced Peter D’s supplied main caps with some BlackGate Std 1000uf caps (no BG N Types left anywhere  ). You need + and – 25 ish volt rails to power them, in my amp this is created using couple of 300Va R-Core transformers (people also recommend good quality torroids). Peter D’s kit has all the rectifiers and PCBs so it very easy to assemble. I am very impressed with the kit, its very nicely designed and gives an extremely pleasing sound when built.

http://www.audiosector.com/lm3875.shtml

I have direct and volume controlled inputs. The volume control is via TVC’s wired before the Gain Clones. I agree with Peter St that direct input from the DAC is better using digital volume control. I spent about £1500 (inc £500 for the TVCs) which is way, way over the top because I went for high spec components, but the amp is still incredible value for money. I retired 5Ks worth of parallel 300B mono block amps when I built the new amp and have not looked back once.

Thinking about it using an active cross between the DAC and Gainclones would be interesting but the experience of using the NOS1 DAC direct connected with digital volume makes me feel that if Peter St cracks the software cross over using the NOS1 that would be the way to go.

I think Peter St would have to provide help with the Juli@ config questions, I am not sure what he would have in mind there.

Nick

[Nick]

Roy,

I missed this one...

PPS: if you dont use software x-overs but just a passive x-over and use bi-amping, how would you connect the interlink to the amp
as 1 cable input and internally y wired to the inputs of the 2xamps per ch. ?

I think you are describing what I am doing. The DAC feeds via a pair of normal (left and right channel) interconnects from the DAC or preamp into the Amp. Inside the amp (for each channel) the inputs either go via the TVC to the inputs of Gainclone 1 and 2 when I want a volume control or in the case of the direct inputs the input RCAs are connected directly to the inputs of Gainclone 1 and 2.

For the Gainclones I have this gives and input impedance (of both Gainclones 1 and 2) of about 12k ohms so you need a preamp / DAC that can drive this input. Its fine for most solid state output stages but I added the TVC so that I could drive the amps inputs with a Valve stage if I wanted to.

Regards,

Nick.

[PeterSt]

This is interesting, I would be tempted to bay pass the SubWFilter, but you have me wondering what the benefit is of the stacked Gainclones ?

Gainclone 2 only sees the bass spectrum passed by the Line Corssover filter which prevents it having to process higher
frequencies ?

Correct. But this is not only about prevention from high frequencies or something, it's a cross over. So, in my case the output of GC2 would be lowpassed at 270Hz, but since the SW can output 120Hz while the normal Woofer goes to 27Hz, the SW is lowpassed at 40Hz - and so forms an "xover" with the normal speaker.
Or I didn't understand your questions perhaps ...

Gainclone 2 maybe has a PSU feeding it that is optimised for good low frequency response (eg more capacitance or something) ?

Exactly. So GC1 and GC12 are not the same.

Some quality of the high gain from having three amp stages ?

Yes, that too. Since the SW is fed with high voltage input (LS output of GC2) - but the SW is made for that - there' more current to flow (and less gain to add by the SW). It just sounds more robust on the SW side.

Perhaps you need this to keep up with the 115db response of your Mid High driver ?

No ... but for the woofer it does. So, all 'n all (and net) it would come down to the woofer having a sensivity of 115dB. Maybe not completely honest, but I think this is what it comes down to. Anyway, where the mid-high would really have that sensitivity, the woofer would calculate the same, but of course it is really GC2 doing that. But don't try to leave out GC1 or GC2 because one tiny GC really would'nt do it for such a 15" driver.

Peter

[PeterSt]

PS: if you want to try using software x-overs, do you need for eg. a second juli@ ? or......?

It will need another "sound card".

[Nick]

Peter,

Thanks for the explanations, interesting stuff. I had not read about anyone using GainClones in this way. Thinking about it  why not ?

All of this has made me start to think about the possible benefits of different cross-over approaches. No plans to act too quickly but defiantly a topic to think about in the background 

Regards,

Nick.

[Scroobius]

Hi Peter,

I am thinking about bi amping my 2 driver speakers with gainclone amps. So with 2 way speakers I will have 4 gainclone amps one feeding each driver. To do this I will need to connect the output of the NOS1 to two gainclone inputs i.e. parallel. Is NOS1 OK to drive this? Is there a minimum impedance that NOS1 should see?

All the best

PC

[PeterSt]

Hi Paul,

That will be no problem. Minimum impedance should be around 350 Ohm.

But I wouldn't do it like that, because you'd be having two different reactances to the one source that way. So, maybe it's better to think "serial". Well, see this topic and my part in it ...

Regards,
Peter

[Nick]

Hi Paul,

That will be no problem. Minimum impedance should be around 350 Ohm.

But I wouldn't do it like that, because you'd be having two different reactances to the one source that way. So, maybe it's better to think "serial". Well, see this topic and my part in it ...

Regards,
Peter

Hi paul,

Peter's suggestion of serial configuration with input gainclone driving two output gainclone is an interesting one. I have not tried it myself but I can say that the NOS1 driving two gainclone in parallel (per channel) works very well. I have used the NOS1 connected directly (volume control by XX) and via my TVCs with no problems.

I'm guessing you'll get a good result with your AN-Es. Will you build the gainclone if you go ahead ?

Nick.

[Scroobius]

Hey Nick,

How are you doing?. Yep I have most of the bits and I am waiting for a few more next week before wielding the soldering iron. So the first thing will be to hear the GainClone (mono block config.) versus my home made SET mono blocks. The thought that el cheapo Gainclone's could sound better than the £5k+ worth of SET mono's is intriguing. First things first though - how will the Gainclones sound versus the SET's?   If that works out OK (but I am listening to the NOS1 - SET's now and it is difficult to imagine how anything could sound better) I will start to think about Gclone bi amping. Fist I will try 2 Gclones in parallel on the output of NOS1 but I have to say Peter has a point - NOS1 driving 2 amps in parallel is not ideal. But there again on the other hand a "serial Gclone setup" needs some thinking about. So far it seems that I would be looking at (assuming I can dig out the LF section of the AN crossovers): -

Gclone1 >> HF xover >> HF drive unit

Gclone1 >> Vol Pot >> LF xover >> Gclone 2 >> LF driver unit

These are just very initial thoughts I have to think more about - not sure it will work yet - but somehow I have to "lose" gain with one Gclone in serial with another. The only other way possibly is to reduce the gain of Gclone 2 to 1:1 but that seems a non starter as the LM3875 needs at least 10:1 closed loop gain to be stable. But as I say only just started thinking about it - any ideas would be welcome though.

All the best

Paul