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DIY SS heater supply

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Posted on February 7, 2016 at 10:26:04
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
Anyone know of a locally (in the USA) available diy ss heater supply. I am looking for something that can provide 5 amps at 10v. Thank you, Dak

 

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high frequency AC, posted on February 7, 2016 at 10:35:20
RayP
Audiophile

Posts: 726
Location: Maryland
Joined: June 30, 2005
Take a look at the high frequency AC solution mentioned towards the end of this link.

I am about to try something similar for a GK71 (20v @ 3 amp).

ray

 

RE: DIY SS heater supply, posted on February 7, 2016 at 10:43:21
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
That's a pretty huge supply if you use a linear with regulation.

You may want to try a SMPS and see if it meets your needs.

 

RE: high frequency AC, posted on February 7, 2016 at 11:00:59
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
Yeah, I checked out his article previously, but I am not sure where one can get that type of transformer. How soon will you be making your amp? I also checked out the tentlab heater supply. That one seems to be very well designed but it costs 200E ! times 2 is about 500.00 plus shipping.

 

RE: Do you know of any recommended circuits? nt, posted on February 7, 2016 at 11:02:43
DAK
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Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
.

 

RE: Do you know of any recommended circuits? nt, posted on February 7, 2016 at 11:12:01
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
You don't want to DIY a SMPS.

I did a 10V/3A regulated DC supply not all that long ago. It required a heatsinked bridge of TO-220 diodes, a heatsinked regulator, three heatsinked beefy transistors, a bunch of lytics, and about 10 or so 5-10W resistors.

The SMPS is a lot more economical and space efficient.

 

RE: high frequency AC, posted on February 7, 2016 at 11:31:53
RayP
Audiophile

Posts: 726
Location: Maryland
Joined: June 30, 2005
I purchased two of the 105 watt versions.

I have added two turns to the output transformer and hopefully will start testing tomorrow. There are 12 turns giving 12 volts. Hopefully the additional 2 turns will make 14 and with the cap (560uf 200v) multiplying by 1.4 I should get 19.6 v which is close enough.

It was easy to add two turns, but three would be tight.

I don't have access to a true RMS meter that can handle the AC frequency but I have an idea for another method to measure the voltage.

I am building the amp right now and it is designed to be light weight (12 pounds).

http://audioratbag.blogspot.com/2016/01/the-heart-attack-special-6s17k-v.html

ray

 

RE: Do you know of any recommended circuits? nt, posted on February 7, 2016 at 11:47:21
Posts: 892
Joined: June 16, 2006
I have built this little supply designed by Pete Millet it works very well.
If you don't want to build a point to point circuit he offers p.c. boards
for it on ebay.

Cal

 

RE: Do you know of any recommended circuits? nt, posted on February 7, 2016 at 12:02:54
DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010
What kind of amp do you have this installed in ? Did you do a comparison with other methods of heater supply in your amp? In my case the amp will be probably my most ambitious project so I am trying to have the best possible circuits while keeping costs within reason. cheers, Dak

 

RE: Do you know of any recommended circuits? nt, posted on February 7, 2016 at 12:14:07
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
That heatsink isn't going to support the required dissipation of this application unless you're willing to have a fan blowing on it.

 

Is that what you want?, posted on February 7, 2016 at 15:46:54
Triode_Kingdom
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Posts: 10012
Location: Central Texas
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Ultrasonic heating is terrific for DHTs used in the output stage. Not so much for drivers and preamps. I've written several short pieces here on the forum about the inexpensive transformers that can be modified for this use. If memory serves, the first one was more than 10 years ago. Search for "ultrasonic" under my name and you'll find them.



 

RE: Is that what you want?, posted on February 7, 2016 at 16:07:53
jorisdallaire
Audiophile

Posts: 356
Location: Quebec city
Joined: July 26, 2012
Hello TK,

Whit the help of the blogspot poster (alexander IRC) and yourself, I went the HFAC route and don't look back since then.

I agree with you, HFAC benefits are say, "less apparent" with drivers, but hey, it's an easy all-around heater solution once you know the basics of those cheap transformers' "hacking".

I am about to try HFAC for heaters on my RIAA preamp. More on this later on!

It's the input of dedicated men like you and Alexander that keep the tube DIY scene alive. Thanks again for your implication.

Cheers,
Joris

 

An oscilloscope..., posted on February 7, 2016 at 16:58:03
jorisdallaire
Audiophile

Posts: 356
Location: Quebec city
Joined: July 26, 2012
... is almost mandatory for measuring at these frequencies. No DVM, even true RMS ones, can measure this reliably.

 

RE: Is that what you want?, posted on February 7, 2016 at 21:25:03
Triode_Kingdom
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Posts: 10012
Location: Central Texas
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Thanks for your comments. The reason I don't generally recommend ultrasonic heating for drivers and preamps has to do with bleed-through. It's a concern that the HF energy might enter the signal path and be amplified in those low level stages. Even if overload isn't an issue, the possibility of IM or spurious responses is much greater than when this energy is used only to heat the output stage.

Keep us posted on your results with the phono preamp. Should be interesting!

 

RE: Thanx for the link, posted on February 8, 2016 at 09:47:11
DAK
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Posts: 2712
Location: PACIFIC
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I will check out your posts and get back to you after I get through reading them. regards, Dak

 

RE: Is that what you want?, posted on February 8, 2016 at 10:23:18
jorisdallaire
Audiophile

Posts: 356
Location: Quebec city
Joined: July 26, 2012
Hello,

For what it's worth, so far I have breadboarded an input stage using HFAC on an indirectly heated pentode in triode mode. From our previous posts I was aware of the risk for oscillation from spurious injection of HF so I scoped it and there was none. That is why I feel confident applying this to my RIAA preamp.

Regards,
Joris

 

HFAC: more thoughts on unsuitability to IDHT input stages, posted on February 8, 2016 at 15:43:53
jorisdallaire
Audiophile

Posts: 356
Location: Quebec city
Joined: July 26, 2012
Just a further precision on what I meant by "unsuitability" through my one and only experience. I was more referring to the sound they produce since in my test there was no other disadvantadge to HFAC. I seem to recall you tried it once as input? I might be mistaken as well - Sorry about that. It's been a while since I messed with these.

However I do I recall you pointing spurious HF emissions to be watched, because that made me push the analysis on the scope more precisely focused on the input stage and overall stability. I must add that the power stage (2 stage amp) was a russian DHT tetrode trioded, also fed from an HFAC module.

The sound is almost unreal because the background just disappears - One must hear it to believe it!

When used on the input stage on breadboard, I found that *somehow* soundwise I still preferred the raw AC approach when hum is no issue as with IDHTs, but not by much.

RIAA preamp is one place where the benefits of HFAC are prominent and justify the *very light* sound trade-off wrt to direct AC, in fact it is not much to pay for silent black background, LF AC almost inevitably causing hum on the high-gain input stage of the preamp.

Just some random thoughts of the moment.
Curious to read your thoughts about the sound as well

Best regards,
Joris


 

RE: high frequency AC, posted on February 10, 2016 at 00:28:47
Alex Kitic
Audiophile

Posts: 182
Location: Serbia
Joined: June 25, 2014
Joris:
I don't recall our email correspondences but if it did happen I certainly don't recall having received feedback about the outcome.
I am very happy that it did work for you!

Phono RIAA: I must admit to simplicity being next to lazyness. Let's put it this way - with indirectly heated tubes in high gain low signal stages, hum is the only issue, and the simplest and probably cheapest and fastest way to deal with it is using or re-using a DC SMTP power supply for HDD. They give slightly more than 12V which is almost perfect for 12.6V heaters, adding a few caps helps stabilizing, filtering, and slowing down a bit - you don't need any more than that. And it's cheap plus fast.

Ray:
Let me know if you need help, and let me in on the outcome!
******

http://rh-amps.blogspot.com/

 

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