Gainclone vs Tripath T Amps Vs Nelson Pass F5

[gobble]

DIY - remember?

Right I meant I dont want it in My BoM.

 

[gobble]

Hi Gobble,

You can use it with your GG pre. Actually, if you don't want to connect the amp to more than one source, you could use a potentio meter to control the gain from the source to the amp. That is what I'm doing right now.

Infact, there is an even better way of doing this by using a LDR (Light Speed Attenuator) by which, you can control gain by changing the resistance using an LED. There is someone in Australia by the name George who supplies these. I'm corresponding with him.

I'm expecting our tech member linuxguru chip in here with his comments.

OK. This site says:

"your source output impedance needs to be less than about 100 ohms which makes it suitable for use with several sources. The Lightspeed Attenuator works best with amplifiers that have input impedance greater than about 50k. If you would like to use the attenuator with a low input impedance amplifier best results are achieved by using a suitable buffer between the attenuator and amplifier. "

DIY "Lightspeed Attenuator" - Passive LDR Volume Control (audio optocouplers)

HTH

 

[captrajesh]

OK. This site says:

"your source output impedance needs to be less than about 100 ohms which makes it suitable for use with several sources. The Lightspeed Attenuator works best with amplifiers that have input impedance greater than about 50k. If you would like to use the attenuator with a low input impedance amplifier best results are achieved by using a suitable buffer between the attenuator and amplifier. "

What did you mean to say?

Are you saying it is not suitable?

 

[keith_correa]

OK. This site says:

"your source output impedance needs to be less than about 100 ohms which makes it suitable for use with several sources. The Lightspeed Attenuator works best with amplifiers that have input impedance greater than about 50k. If you would like to use the attenuator with a low input impedance amplifier best results are achieved by using a suitable buffer between the attenuator and amplifier. "

DIY "Lightspeed Attenuator" - Passive LDR Volume Control (audio optocouplers)

HTH

In the GB of the myRef Premium BOM kit, Uriah [who organized the GB and who also wrote the diyaudioprojects article] also offered to sell the Lightspeed boards + parts at a discount along with the myRef kit. What was not included was the PSU for the Lightspeed.

Cap'n instead of George try Uriah - he offers kits here

 

[gobble]

What did you mean to say?

Are you saying it is not suitable?

You will need another buffer or a preamp that provides around 100ohm output impedance. the input impedance of the GC may be suitable.

So either you spend $$$ on CDP with <100Ohm output imp or another buffer stage. The latter case means yet another set of audiophile IC's costing $$$ and you will have 4 sound influencers in the chain -

1. The CDP,
2. The CDP<>Buffer IC
3. The Buffer
4. The Buffer<>GC IC

Think about it. hyeah:hyeah:hyeah:

The o/p impedance of a budget audiophile CDP is usually in the range of 300ohms.

 

[linuxguru]

OK, will this think have a pre-out and main-in? that way I can switch between the grounded Grid and the GainClone pre stage depending on which one I like.

It's only a power amp board with a single, high-Z (100k) input. You can couple any line-level signal of about 0.5-0.8 V (peak) into it. I use the line output of an Audigy 2 soundcard, for instance, to test it.

There is no pre-amplifier on board, so you can use an external pre- if you wish. There's no need for it in practice, unless you want tone controls.

 

[captrajesh]

It's only a power amp board with a single, high-Z (100k) input. You can do couple any line-level signal of about 0.5-0.8 V (peak) into it. I use the line output of an Audigy 2 soundcard, for instance, to test it.

There is no pre-amplifier on board, so you can use an external pre- if you wish. There's no need for it in practice, unless you want tone controls.

Then how do you control volume?

 

[linuxguru]

Quick questions: Is it only a power section or an integrated? Whats the rms per channel?

It's only a monoblock power section. You need 2 boards + transformer, switches, cabling, chassis components, connectors, etc. to make a full-fledged power amp.

RMS per channel varies depending on the rail voltages and load. With the recommended +/- 32V and 8 ohms load, it will max out at about 40W/ch before clipping. It's not a limitation of the LM3886 chipamp, which is rated for 68W/ch. You can probably get a bit more power (up to 60W) with +/- 35V rails.

 

[linuxguru]

Then how do you control volume?

You can use the volume control on your source, or use a simple grounded potentiometer rigged as a voltage divider, or use an external preamp. It's entirely up to you.

 

[linuxguru]

Are you saying it is not suitable?

The Lightspeed LDR-based passive attenuator will work well with the MyRef, and in fact, Uriah offers kits of the Lightspeed for this very application.

 

[gobble]

It's only a monoblock power section. You need 2 boards + transformer, switches, cabling, chassis components, connectors, etc. to make a full-fledged power amp.

RMS per channel varies depending on the rail voltages and load. With the recommended +/- 32V and 8 ohms load, it will max out at about 40W/ch before clipping. It's not a limitation of the LM3886 chipamp, which is rated for 68W/ch. You can probably get a bit more power (up to 60W) with +/- 35V rails.

OK, I would like one with +/- 35V rails if possible ... Or is it not possible since the PCB is already made?

 

[quad]

George's lightspeed (and Uriah's clone) are quite simple to rig up
on a general purpose board, provided you can get matched
Silonex NSL-32SR2 Optocouplers.

DIY "Lightspeed Attenuator" - Passive LDR Volume Control (audio optocouplers)

For the MyRef, Mauro recommended a 10K log stereo pot for the
volume control. I used a 50K, and it works for me.
Something like this would do just fine -

DACT Type 21 Stepped Attenuator Volume 10K Preamp - eBay (item 200442532840 end time Jul-22-10 07:22:53 PDT)

For the power transformer, Mauro recommended a 24-0-24V, min of 250VA (I forget the details, but I think it's to do with
the LM318 voltages, which he generates using zeners).

 

[linuxguru]

Re: Option

If buying the boards from Uriah is the way we will go, one option is to ask someone who is coming from the US to get the boards for us. Will save shipping costs.

Update: Uriah has replied that he will not sell the boards in bulk to me (I had asked for 20 sets, i.e. 40 boards). However, there's no reason why he won't sell them to individual buyers who're willing to pay the list price + shipping.

Siva, you are saying "re-design a PCB". What existing design [PCB layout] do you intend modifying?

I have almost finished modifying the Twisted Pear board, revision 1.2 by Russ White. This layout (Eagle .sch and .brd files) was voluntarily posted in a public forum by him, so it's fair game to modify it. However, I will need his permission before redistributing PCBs incorporating my modifications - I'll ask when I'm done.

Related stuff: Is anybody in Bangalore good at getting a usable Gerber file from an Eagle PCB .brd file, and getting good double-sided PTH boards out of it, from a local PCB house? Drop me a note if you can volunteer your time and energy, or even just some pointers to help me go about it.

 

[Hiten]

Re: Option

Related stuff: Is anybody in Bangalore good at getting a usable Gerber file from an Eagle PCB .brd file, and getting good double-sided PTH boards out of it, from a local PCB house? Drop me a note if you can volunteer your time and energy, or even just some pointers to help me go about it.

Linuxguru
found this on DIY site. has PCB maker's address. (two years old postings.)
PCB makers in Bangalore, India - diyAudio

 

[linuxguru]

OK, I would like one with +/- 35V rails if possible ... Or is it not possible since the PCB is already made?

The PCB and the circuit therein support a range of power supply voltages - I need to check this out, but anywhere from +/-24V to +/-36V should be ok. You can go even lower if you change a couple of resistors that are part of the LM318 shunt regulator circuit.

The power supply voltages are largely a function of the transformer that is used. 24-0-24 should give you approx. +/- 32V, which is the recommended rail voltage for the MyRef, where the sonics are generally considered optimal.

 

[gobble]

OK. Lets now get this started. Consider me as a confirmed member for the group buy, whatever your source for the PCB.

Cheers

 

[gobble]

LinuxGuru

Forgot to tell you - I intend to build both the GC and F5. Hence I need a common Tranny and PSU in an external enclosure with IEC socket, so I can swap the power section when the mood dictates.

I will need you help in evaluating the psu components and implementation of both amps and confirming what will work in common for the two. Or tweak it to work for both.

Hope you will kindly provide your time and advice for this. I only know how to solder

Regards

 

[linuxguru]

Today's Updates:

1. Mauro Penasa has kindly given permission for a PCB re-design based on his MyRef Rev C schematic. His only conditions are that the origin of the project must be recognized, and if anybody becomes a millionaire selling his gainclone design, they should remember him. Both conditions are easily met - Yippee!

2. As a test, I was able to create working Gerber files for all relevant layers required by one of the local PCB fabrication houses. Now I only need to fine-tune the layout before I freeze it and go golden, maybe within a week.

3. The value BoM is also mostly stable, just a few more parts to test and stabilize.

 

[denom]

Dear Linuxguru, Gobble, Hitensitapara & others who are attempting the build,

Would highly appreciate the final outcome of the build, with total cost & performance report, for it will be a roaring success if all criteria's with respect to performance & price are met with. Am sure many on the forum would be interested in purchasing fully built up units.

Eagerly await the results
Regards

 

[keith_correa]

Today's Updates:

1. Mauro Penasa has kindly given permission for a PCB re-design based on his MyRef Rev C schematic. His only conditions are that the origin of the project must be recognized, and if anybody becomes a millionaire selling his gainclone design, they should remember him. Both conditions are easily met - Yippee!

2. As a test, I was able to create working Gerber files for all relevant layers required by one of the local PCB fabrication houses. Now I only need to fine-tune the layout before I freeze it and go golden, maybe within a week.

3. The value BoM is also mostly stable, just a few more parts to test and stabilize.

:clapping: :clapping: Did you ask Russ yet or are you going to wait for the proto to be done before you do?