Gainclone heaven ?

[Nick]

Nick - your amp is looking very nice!. So much so I have succumbed to temptation and have started ordering parts to build one myself!!. I probably have enough parts here to convert my existing amp into balanced mode (except transformers of course) but that would mean an unacceptable period of time without music. Also I think I have a buyer for the existing amp. so I should recover costs.

The layout will be slightly different (I just need to double check I can do it though) and I will be using Blackgate NX decoupling caps as I am using at the moment.

Looking forward to dusting off my soldering iron. 

Do you find the balanced amp generates significantly more heat?

Happy days!!

Paul

Paul hi,

Regards the heat it runs warmer but not that much. The playing at -30db out of the NOS (which is louder because of the balanced design compared to single ended) the amp just gets warn, say 40 deg C on the case sides. The copper heat sink arrangement in the Modu case seems to work very well so the chips are the same temp as the case.

The NOS1 appears to have no problem driving 8 amp modules. I think using your Black gates as input caps would be a good move, the Mondorfs I have are only 5.8uf and are driving two amp modules per capacitor so they are theoretically marginal for the -3db low pass point, but I have to say that listening the much stronger, snappier base is a big feature of the sound so the 5.8uf caps are ok for now.

I would be tempted to build new a new amp myself. It would be worth having a chat off line, I spent quite a while working out the details of the signal earth, heat sink and setup the case work / wiring. If you use the same layout I can help with some ideas and pointers on materials etc.

Besides the sound quality, the amp behaves in a very civilised way, absolutely no clicks or pops turning on and off and very very quiet (save for a small amount of transformer hum from one of the transformers, need to think if this is worth changing out the transformer for).

The amp has a very valve like warmth and presence but with detail and extension at both ends. I guarantee you will not regret building one for your system (except the hours and hours it takes ha ha  ).

Happy to pop down with it if you want to try it in your system.

Speak soon,

Nick.

[manisandher]

Nice job Nick!

Happy to pop down with it if you want to try it in your system.

And I'd be happy to bring along my BD-Design monos if you'd like. Could be an interesting gathering...

Mani.

[Scroobius]

Mani - Nick I will check diary and get back to you later with possible dates.

Looking forward to it already.

Paul

[Nick]

Nice job Nick!

Happy to pop down with it if you want to try it in your system.

And I'd be happy to bring along my BD-Design monos if you'd like. Could be an interesting gathering...

Mani.

Sounds like fun Mani, that would be great.

From the internal shots of Berts amps its looks like there are some very fine components in them. It will be really interesting to see how Berts parallel bridged design with input buffering (I think) compares to the Bii-amped bridged approach I have taken.

I am sure there will be some nice sounds 

Regards,

Nick.

PS could you bring any balanced interconnects along that you rate ? At the moment I am using a set I make up for the new amp which are loosely based on a VH Audio diy recipe that Paul put me onto, but I'm keen to hear other good cables.

[Scroobius]

At last the parts are here and I have now started to build a bridged biamped GainClone similar to Nick's. But there there will be some differences in layout. I will post pictures as I go along. Nick bought his balanced GainClone here yesterday and both Nick and I will post what happened during the day. Suffice to say my enthusiasm to build is even more than it was before now that I have heard it!!

The following is a picture of the amplifier so far!!

Nick and I have learnt from each others experiences building these GainClones and we will post of summary of all the things we consider to be important at the end of the build.

Can't wait to get my drill out and start filling those boxes!!.

Regards

Paul

[Scroobius]

Nervous times - settling on the layout of the amp is the "point of no return" when holes are being drilled in the cases. Anyway the supplier of my copper heat sink let me down and so I decided to go ahead without the copper and bolt the chips direct onto the case sides. That will make wiring later more more difficult but doable.

Just a little concerned that passing the ps wiring through the side of the case is not ideal because it is after all a heat sink. But there is little option really - I used 10mm OD rubber tubing to protect the wiring through the 13mm transit holes (the rubber expands when the wiring is pulled through). I had to use talcum powder to get the wiring through the rubber tubing as it was a tight fit but not too difficult really. The advantage is that the amplifier smells great!!.

Drilling big holes through the profiled sides of the case is not easy great care is needed.

By the way I drilled and then tapped the holes used to bolt the chips to the case side because it is difficult to get access to the back of the case side and I will want to remove those amp boards later to match offsets. Also I really like running a tap through a hole - it is just one of the jobs is very satisfying!

Regards

Paul

[Scroobius]

Power in and working - the transformers will shortly be bolted down Peter!!

[Scroobius]

All the hardware finished and started to wire up amp modules. Amp modules have been selected to minimise offset voltages at the speaker terminals. Lucky that four of the modules had offsets of 54 to 57mv so offset voltages should be very low of the order of 1 to 3mv (hopefully!!!) to the LF units. Offsets at the HF units not so important but even so will only be of the order 15-30mv but as there is a capacitor in the crossover that is not an issue.

[PeterSt]

Another super nice "drawing" appeared !

Nice job so far Paul. Super nice ...

[Scroobius]

Earthing is the next challenge....... watch this space!!!

[Nick]

Paul,

It's looking very nice, not far to go now ! Really looking forwards to having a listen to your finished amp. There are subtle differences in our builds, will they be audible I wonder ?

Cheers,

Nick.

[Scroobius]

Power lines wired up to amplifier boards and earthing wired in. Last step to come is to wire up speaker binding posts and XLR's. I have to say this has turned out to be a much bigger project than I had anticipated - if I had not heard Nick's amp at this stage I would have been wondering if the effort would have been worth it. At least I know the answer to that!!.

[PeterSt]

Hey Paul,

Assuming you caught some sleep last night - thus while you still have a chance : Make all of your output wires exactly as long.

Peter

[Scroobius]

At last - another early morning start and the amp is finished. I totally underestimated the work - this was a big project eight amplifiers in one box is a lot of wiring and when you try to make the wiring neat the time increases a lot. A check of the offsets showed just +3mv and -4mv to the LF drivers. So how does it sound? well no surprise just like Nick's when he brought it here. The main difference is the sheer effortless presentation of the music, the sound is bigger stretching beyond the speakers bass extremely well controlled all clearly delineated. The difference with a balanced setup is not subtle at all. The only downside at the moment is that the sound has a slight rough edge but the amp has just been switched on and so needs some running in. Also the interconnects I made use transformer wire and I will be rebuilding them with fine silver wire which is what sounded best when Nick came here. My old setup used the fine silver interconnect and it makes a significant improvement to my system.

A big thanks to Nick for the inspiration to build this amp - the SQ is really top notch. Ros and I will shortly be going to visit Nick and I shall be taking the amp with me to compare with Nick's. That may sound odd but we have found it really beneficial to compare our amps it is the only way to iron out any small problems that we would not otherwise find. We will post more after that visit.

If you are thinking about building a balanced bi amped amp do not hesitate do it you will not regret it (except the amount of work perhaps).

If anyone wants to know more information do not hesitate to post - Nick and I have been through the "pain" and we would be happy to share our experiences if it helps.

Paul

PS - Oh just one thing - when running at high volume (-21db with my 98db sensitivity speakers) and with a highish ambient temperature the heat sinks on my amp get very hot ~ 45deg C so I will have to look at improving that. Nick does not have a problem with his 115db speakers. I am using the whole case of my amp as a heat sink. Each amp is now seeing 4ohms output Z so significantly more current being delivered to the speakers.

PPS - Also I started off with earthing arrangement as I had previously i.e. with L and R channel grounds not connected to each other and not connected to PE - the result was that there was some "mains hum" through the left speaker and less through the right speaker. I then connected L and R channel grounds to PE - the result? total silence no noise at all through either L or R speakers. So the grounding requirements for balanced amp is different - not totally surprising but the only way to find out is to experiment.

Watch this space for more info ..............

[PeterSt]

Hey Paul, remember this one ? http://www.phasure.com/index.php?topic=642.msg14360#msg14360 (bottom picture in that post)
I counted 75 pieces of cut wire there, and this was from the final assembly of one NOS1.

But your end product looks nicely tidey and neat !
Good result on the DC Offset as well (eh, how couldn't you hehe)


So, N&P Productions ... is it actually common these days to see GainClones in a balanced setup ?