GM70 SET
#286 Re: GM70 SET
Try another card Paul?
- Paul Barker
- Social Sevices have been notified
- Posts: 8984
- Joined: Mon May 21, 2007 9:42 pm
#287 Re: GM70 SET
I thought that but it's linked to my business bank account as I am a business user. I purchased a work related item over the weekend and it worked fine. It seems to be a problem with the seller. As it is a weekend no response from seller as of yet.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
- Paul Barker
- Social Sevices have been notified
- Posts: 8984
- Joined: Mon May 21, 2007 9:42 pm
#288 Re: GM70 SET
It turns out Russian Government won't allow PayPal purchases by businesses outside Russia. That is to say a Russian Business cannot sell to a UK Business.
So the seller has sent me a payment request via a USA organisation which is set up to solve this problem.
I have paid their invoice. So I may get some valves or I may have been scammed. But as he has 100% feedback, probably OK.
Putin I suppose.
So the seller has sent me a payment request via a USA organisation which is set up to solve this problem.
I have paid their invoice. So I may get some valves or I may have been scammed. But as he has 100% feedback, probably OK.
Putin I suppose.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
- Dave the bass
- Amstrad Tower of Power
- Posts: 12276
- Joined: Tue May 22, 2007 4:36 pm
- Location: NW Kent, Darn Sarf innit.
#289 Re: GM70 SET
Yeah, thats the best way I reckon.Paul Barker wrote:
Putin I suppose.
He has a box, he has some valves, he has a fella on the other side of the world that wants them and has paid for them in advance. So...
Putin box and send them to him...
Ha! SWIDT?
"The fat bourgeois and his doppelganger"
- andrew Ivimey
- Social Sevices have been notified
- Posts: 8318
- Joined: Mon Jun 11, 2007 8:33 am
- Location: Bedford
#290 Re: GM70 SET
Witty,very witty!
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
- Dave the bass
- Amstrad Tower of Power
- Posts: 12276
- Joined: Tue May 22, 2007 4:36 pm
- Location: NW Kent, Darn Sarf innit.
#291 Re: GM70 SET
It was one of .....andrew Ivimey wrote:Witty,very witty!
Ha!
"The fat bourgeois and his doppelganger"
-
- Thermionic Monk Status
- Posts: 5643
- Joined: Thu May 24, 2007 11:22 am
- Location: People's Republic of South Yorkshire
#292 Re: GM70 SET
It's about time I got this boxed up, and I think monoblocks is the way to go for various reasons.
I reckon I have pretty much most bits I need for 2 amps, though I might need some more trafos. I'm sold on separate HT supplies for the 12GN7 driver so I need a couple of 25VA mains transformers. But I'm wondering whether I can get away without a 6.3V trafo by sharing an existing winding for the 12GN7 and 2 6AX4 damper diode heaters...
Now ordinarily I wouldn't even consider having the signal and rectifier valves on the same winding, but I have a couple of Tentlab heater supplies which at <1A can supply 6.3V DC out for 6.3V AC in.
http://www.tentlabs.com/Products/Tubeam ... index.html
The question is how likely is the regulator to shield the 12GN7 from the 6AX4 switching spikes etc.? As far as I can see it's "just" a low drop chip regulator so would probably do an adequate job, but not as good as galvanic isolation.
Thoughts?
I think I'm inclined to get a couple of Hammond 266JB6 (6.3V 1.2A) from Philip Ramsey for the 12GN7s and run the dampers of the mains tx. They're £12 each inc. vat, how the 0.3A versions are £31 each I don't know.
I reckon I have pretty much most bits I need for 2 amps, though I might need some more trafos. I'm sold on separate HT supplies for the 12GN7 driver so I need a couple of 25VA mains transformers. But I'm wondering whether I can get away without a 6.3V trafo by sharing an existing winding for the 12GN7 and 2 6AX4 damper diode heaters...
Now ordinarily I wouldn't even consider having the signal and rectifier valves on the same winding, but I have a couple of Tentlab heater supplies which at <1A can supply 6.3V DC out for 6.3V AC in.
http://www.tentlabs.com/Products/Tubeam ... index.html
The question is how likely is the regulator to shield the 12GN7 from the 6AX4 switching spikes etc.? As far as I can see it's "just" a low drop chip regulator so would probably do an adequate job, but not as good as galvanic isolation.
Thoughts?
I think I'm inclined to get a couple of Hammond 266JB6 (6.3V 1.2A) from Philip Ramsey for the 12GN7s and run the dampers of the mains tx. They're £12 each inc. vat, how the 0.3A versions are £31 each I don't know.
#293 Re: GM70 SET
Hi Simon
I've got a 266 PA6 sitting on the shelf which just failed to sell on ebay...it may be ott for your requirement though:
6.3v @ 6a or 12.6 @ 3a
also a couple of Coleman heavy duty regs with big heatsinks I was using them for 6.3v @ 4 amps....
I've got a 266 PA6 sitting on the shelf which just failed to sell on ebay...it may be ott for your requirement though:
6.3v @ 6a or 12.6 @ 3a
also a couple of Coleman heavy duty regs with big heatsinks I was using them for 6.3v @ 4 amps....
Last edited by ed on Thu Apr 26, 2018 12:25 pm, edited 1 time in total.
There's nowhere you can be that isn't where you're meant to be
#294 Re: GM70 SET
I reckon pulses would still get past the reg board, id just get hold of some tx's. A couple of 6v toroids would do the job fine for the diodes
Edit: wot ed said
Edit: wot ed said
- pre65
- Amstrad Tower of Power
- Posts: 21399
- Joined: Wed Aug 22, 2007 11:13 pm
- Location: North Essex/Suffolk border.
#295 Re: GM70 SET
I use a 9v 10va frame transformer, then 2 X 1R then a DIY Hi-fi ultra low noise module for the 12GN7 on my GK71 amp.
The 1R just drop the volts enough to stop the module heatsink getting too hot.
The 1R just drop the volts enough to stop the module heatsink getting too hot.
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
-
- Thermionic Monk Status
- Posts: 5643
- Joined: Thu May 24, 2007 11:22 am
- Location: People's Republic of South Yorkshire
#296 Re: GM70 SET
Thanks ed, but I need 2, one for each mono.
I should probably have been a bit clearer - if I have separate trafos I'll most likely just run the 12GN7s on AC, they work fine like this. The Tentlabs are just a thought to enable me to potentially use the same winding.
I should probably have been a bit clearer - if I have separate trafos I'll most likely just run the 12GN7s on AC, they work fine like this. The Tentlabs are just a thought to enable me to potentially use the same winding.
- pre65
- Amstrad Tower of Power
- Posts: 21399
- Joined: Wed Aug 22, 2007 11:13 pm
- Location: North Essex/Suffolk border.
#297 Re: GM70 SET
If I were doing another one I'd probably use some LT1083 modules off Ebay for under a tenner each.
Like this
https://www.ebay.co.uk/itm/LT1083CP-Lin ... 1438.l2649
Like this
https://www.ebay.co.uk/itm/LT1083CP-Lin ... 1438.l2649
The only thing necessary for the triumph of evil is for good men to do nothing.
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
Edmund Burke
G-Popz THE easy listening connoisseur. (Philip)
-
- Thermionic Monk Status
- Posts: 5643
- Joined: Thu May 24, 2007 11:22 am
- Location: People's Republic of South Yorkshire
#298 Re: GM70 SET
Sigh. Nearly another year has passed and I'm no further forward, surely this year won't be as horrid as last...
Of course, the problem with DIY is nothing's ever "finished" and I'm now considering a slightly different tack which I would appreciate the panel's views on.
The Quasars are no more (sorry James) - I'm using the GM70 amp directly coupled to the FE208Esigmas from 150Hz up on a plain baffle, and a couple of cheap 3116 class D subwoofer amps (with built in 180Hz low pass filters) directly coupled to the 285GMFs in H frames. Removing the series crossovers was an obvious improvement when I first tried it in the Quasars, even with £25 of Chinese class D amp and a SMPS PS.
To control 2 amps needs some kind of pre/control amp to split the signal and balance the volume from each driver. I'm a little reluctant to add another stage, like a 26 say, as I don't need any more gain. So I wonder about putting the 12GN7 in the pre and leave just the GM70 outputs in the power amp. I think I'll end up with a valve amp driving the 285GMFs too, so what are the pros and cons of sharing the driver valve and then splitting the signal to two separate amps?
I can't ever remember seeing this type of arrangement so I'm a little sceptical of how well this might work. I think I'd need something like a White cathode follower after the driver to drive the cables to the output valves, but what are people's thoughts?
Of course, the problem with DIY is nothing's ever "finished" and I'm now considering a slightly different tack which I would appreciate the panel's views on.
The Quasars are no more (sorry James) - I'm using the GM70 amp directly coupled to the FE208Esigmas from 150Hz up on a plain baffle, and a couple of cheap 3116 class D subwoofer amps (with built in 180Hz low pass filters) directly coupled to the 285GMFs in H frames. Removing the series crossovers was an obvious improvement when I first tried it in the Quasars, even with £25 of Chinese class D amp and a SMPS PS.
To control 2 amps needs some kind of pre/control amp to split the signal and balance the volume from each driver. I'm a little reluctant to add another stage, like a 26 say, as I don't need any more gain. So I wonder about putting the 12GN7 in the pre and leave just the GM70 outputs in the power amp. I think I'll end up with a valve amp driving the 285GMFs too, so what are the pros and cons of sharing the driver valve and then splitting the signal to two separate amps?
I can't ever remember seeing this type of arrangement so I'm a little sceptical of how well this might work. I think I'd need something like a White cathode follower after the driver to drive the cables to the output valves, but what are people's thoughts?
#299 Re: GM70 SET
slightly OT with respect to GM70 but:
I'm watching with interest Simon...do it, do it....
It's not a million miles from the thing I was working on when I had a bit of a rest in 2014. It was prompted by the failure of the AMT OB. I never picked it up again later...maybe I should.
those TPA3116 are awesome in my opinion and I still use one to drive the electrostatics.
there is a volcontrol/attenuator in each tpa3116 which would be adjusted to balance the two drivers(using clio to save the risk of madness)
I'm watching with interest Simon...do it, do it....
It's not a million miles from the thing I was working on when I had a bit of a rest in 2014. It was prompted by the failure of the AMT OB. I never picked it up again later...maybe I should.
those TPA3116 are awesome in my opinion and I still use one to drive the electrostatics.
there is a volcontrol/attenuator in each tpa3116 which would be adjusted to balance the two drivers(using clio to save the risk of madness)
There's nowhere you can be that isn't where you're meant to be
#300 Re: GM70 SET
I did something similar with my first 211. 76 + 45 driver stage in one box, coax to the 211 grid. Should be fine. I would think that unless you are going via Manchester the extra capacitance of the coax would not be a problem for the pentode driver.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.