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PostPosted: 04 Oct 2012, 11:45 
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Location: Lisbon, Portugal
Soundbrigade wrote:
I would go for something heavier.
Hpw about a pair of LM-9911U-B from http://www.vt4c.com/shop/program/main.p ... group_id=7
Or check Edcor.


I´m sorry, but I completely disagree with you.

All the transformers shown on that shop are made in China.

How can you compare them with Edcor?

There was one time, I decided to build a cheap tube amplifier, of course with Chinese goods... And the end of the project I ended-up with a poor audio response (apart from other issues).

So what is the idea? I have spent the same working hours and skills. Got tired for what?

It just doesn´t worth...

Do it right, or just don´t do it at all!


Cheers,

Miguel


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PostPosted: 04 Oct 2012, 13:28 
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Joined: 02 Mar 2009, 12:41
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Location: Vänersborg, Sweden
I partly agree with you.
With the limited finacial situation I'm in I try to find the best compromise between price and quality. Among stuff of good quality and low price are products from VT4C (in HongKong) from where I've bought a lot through the years and never have been disappointed.
I like EDcor as well, though including postage and VAT an iron from the States becomes unnecessary expensive.

However there are cheap AND reasonable good transformers to be found almost everywhere IF you go for low power, but looking for a 50, 70 ... 100W transformer you don't have many choices at all and hardly no choices looking for a good budget transformer. My 25W SE-transformers put me back 150 USD 8 years ago when I bought them, not they are around 250 USD in Sweden. Today I'd look for an EDcore or check what I can get from the Netherlands ...

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PostPosted: 04 Oct 2012, 16:36 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
I mainly use Hammond and Edcor. I have found the Edcors excellent value for money even with the added expense of shipping iron from the US to Australia. I think the Hammonds may be slightly better across the board. The only further comment I would make is if you are looking to make a better sounding amp and not just "knocking" something up for the fun of it go for the better Edcors. As I found with my latest EL34 build the XSE OPTs, even at 15W for a 5W amp, lack the very bottom end. But Edcor do make this quite clear with their specs. Once more I think the non-Asian components, though pricier, perform better unless you get into some very exclusive high-end Asian products.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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PostPosted: 19 Oct 2012, 22:01 
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Joined: 19 Oct 2012, 20:42
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Hey guys, new to this forum. I was looking at Hammond's SE output transformers and found they have some 30 models. My question is for Mr. Houston. Your Be amp with KT120's, how much power do they put out?


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PostPosted: 20 Oct 2012, 16:59 
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That should have been some 30 watt models. It seems that with a mu of 20 6SN7 can't possibly swing enough voltage to drive a KT120? It seems like it should have another gain stage in their? Possibly a 6SL7?


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PostPosted: 20 Oct 2012, 18:23 
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@mr2racer: I'm probably not the best person to ask. The original Be Bamp was designed for KT88 and EL34s. It had a 6N1P or 6SN7 driver tubes (plug-n-play front-ends). The OPTs were cheap Edcor 15W types. When I put the KT120s in I dropped the the cathode resistors to allow more current through the tube. The Edcor OPTs would have been close to saturation so I never really got the full benefit of the tubes. Also the OPTs were 5K types and to get more power from the KT120 I'm guessing a lower primary impedance would be required.

Hopefully some of the others will offer more guidance.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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PostPosted: 21 Oct 2012, 06:40 
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Joined: 25 Sep 2012, 20:25
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Can you connect 2 OPTs in parallel to increase power rating?


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PostPosted: 21 Oct 2012, 08:35 
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7_V wrote:
Can you connect 2 OPTs in parallel to increase power rating?


I´m not sure...

But it won´t help to keep a good, clean and low distortion sound for sure... :\


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PostPosted: 21 Oct 2012, 09:52 
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7_V wrote:
Can you connect 2 OPTs in parallel to increase power rating?
NO!

No two transformers have the same magnetic hysteresis loop. As such the waveforms never quite follow each other and the results are very poor. If you go from class A to class AB you can even destroy your tubes. This is not a bandaid you should ever try. IMHO.

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PostPosted: 21 Oct 2012, 10:05 
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Joined: 25 Sep 2012, 20:25
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Ok, just a thought. Thanks.


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