My new (made in Calcutta) Tube amplifier

Audiolab 7000CDT CD Transport
Hari Iyer said:
Looking at the images posted, the driver tubes are on the front side and the RCA at the back side. The signal path is too long which has to cross power lines, OPTs, final tubes and then reach the driver grid. Why can't you cancel the RCA from behind and have it somewhere in between the driver tubes. This will help reduce noise and improve S/N ratio. My 2 cents.

In my DIY tube amp, I have kept the driver tube just behind the RCA for short signal path.
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I can hardly comment on this Mr. Iyer :)

bhaskarcan said:
Prem, Shantanu's (Madman29) diy speakers are one of a kind. It's a JBL/Altec clone with front loaded horn and 15inch mid-bass, crossed actively.
Drivers are FaitalPRO.
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Bhaskar Da provided me some invaluable support during the build. To go active for the crossovers was his idea too
You can find a build thread here

Calpamos two way

After building the THAM15 subwoofer I realised that my focal chorus 726V is not going to match in sound stage with it. So I started looking for a project involving 15" mid woofer and compression driver+horn combo. I liked the Calpamos project of Humble home made hifi. The FaitalPro drivers were...
www.hifivision.com www.hifivision.com
 
madman29 said:
I can hardly comment on this Mr. Iyer :)
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It's ok if noise and hum is not an issue. Also the left and right OPT are quite close to each other. Hope they don't couple. Check if you can reverse one of them at 90deg to cancel phase or atleast reverse them by 180 Deg. It's good that the final tubes are facing the OPT core.
 
Madman29 is not the designer of the amplifier discussed here. He is just the end user. He auditioned the amp, liked the sound and bought it. From his feedback, it's apparent that he continues to enjoy it in his setup which matters most.
We should not mess up with his listening pleasure by highlighting the design pitfalls, if any, and other technical nitty gritties. Even if he learns about the so called drawbacks with respect to components used or layout of the amp, being the not so technical end user he can only lose his sleep over them or return the amp to the maker and request for an upgraded version involving extra cost. In the process his previous positive experience will be lost. And the new version may or may not guaranty better listening experience since it will be a new design.
IMHO, we must allow OP to enjoy his new toy to the fullest for the time being..... :) :)
 
bhaskarcan said:
Madman29 is not the designer of the amplifier discussed here. He is just the end user. He auditioned the amp, liked the sound and bought it. From his feedback, it's apparent that he continues to enjoy it in his setup which matters most.
We should not mess up with his listening pleasure by highlighting the design pitfalls, if any, and other technical nitty gritties. Even if he learns about the so called drawbacks with respect to components used or layout of the amp, being the not so technical end user he can only lose his sleep over them or return the amp to the maker and request for an upgraded version involving extra cost. In the process his previous positive experience will be lost. And the new version may or may not guaranty better listening experience since it will be a new design.
IMHO, we must allow OP to enjoy his new toy to the fullest for the time being..... :) :)
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This was suggested bin spirit of DIY - that's all. If the owner enjoys - NOTHING else matters. Enjoy.
 
Samwah caps are not that bad actually, i use Samwah caps if the owners of amps that I repair, are on a budget. The trick with them is to get new stock and not stored stock :) (now that's a trade secret for you). Samwah caps work great in NAD amplifiers. I have started using them in tube amps and DD turntables as well (not sure about their eventual lifespan though).

What a lovely amp though, if it were built by some audiophile guru in the US or UK, it may have been splashed across webpages around the world. Amplifier building is a dying art in India, it is up to our generation to revive it.
 
reubensm said:
Samwah caps are not that bad actually, i use Samwah caps if the owners of amps that I repair, are on a budget. The trick with them is to get new stock and not stored stock :) (now that's a trade secret for you). Samwah caps work great in NAD amplifiers. I have started using them in tube amps and DD turntables as well (not sure about their eventual lifespan though).



What a lovely amp though, if it were built by some audiophile guru in the US or UK, it may have been splashed across webpages around the world. Amplifier building is a dying art in India, it is up to our generation to revive it.
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I agree with you Reuben. We should appreciate the good quality work at very reasonable price. That is the beauty of it.
 
If I had a high efficiency speaker, I would have given the amp a shot. It looks very promising.
 
How much high should be the high efficiency? JBLs are 94dB+ and for your room size they are quite high imo. You can double your speaker cable for additional efficiency.
 
JBL is 94db but it’s a 4 way. It needs at least 20 watts to sing. Also 15 inch drivers need watts to wake them up. If 10 watts was enough I would never have sold my Berning. If it was a single driver 95 dB, 6 watts could have been worth a gamble.
 
Aren't the 4 way or single driver only for the eyes? For the ears do they matter? 94dB for ears should be same either way? Wondering.
 
I am not a technical guy but AFAIK crossovers for a 4 way is more complex than a very simple first order crossover. Because of the complex crossover, power requirements go up. That’s what I have been told

Surprisingly Tannoys also which are like 94-96db need power. They need at least 20-30 watts to get them to sing. But Tannoy is a concentric driver. So I don’t know why a low powered amp doesn’t work well with it.

I believe my JBL is the last of the 43xx series which works with a 20 watt amp. All later models need much more power even though they too are 94 dB efficient.
 
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prem said:
I am not a technical guy but AFAIK crossovers for a 4 way is more complex than a very simple first order crossover. Because of the complex crossover, power requirements go up. That’s what I have been told

Surprisingly Tannoys also which are like 94-96db need power. They need at least 20-30 watts to get them to sing. But Tannoy is a concentric driver. So I don’t know why a low powered amp doesn’t work well with it.

I believe my JBL is the last of the 43xx series which works with a 20 watt amp. All later models need much more power even though they too are 94 dB efficient.
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In my case this amplifier is only driving my compression driver /tweeter which is crossed over at 1400hz. It is a metal (titanium) dome and sensitivity is 108 db. So it the amp with 6 watts per channel is doing pretty well. The 15" mid-bass driver is driven by a solid state amplifier, and that amplifier is very powerful. As a crossover I am using a dbx234xs. And to tune the sound to my likeness I am using a Klark Teknik DN360 equalizer.

It might sound complicated but it works quiet nicely.
 
While casually surfing through internals of various well regarded audio products, I came across some pictures of Sugden Audio amplifiers which attracted my attention. Seems that for their top of the line components like A21SE Signature or Masterclass FPA-4 amplifiers, Sugden's choice of electrolytic capacitors are none other than Samwha. Not only as power filter banks but also on the signal boards.
This makes me wonder if a highly reputed brand like Sugden can use Samwha electrolytics in their prestigious offerings without any hesitation, should there be any reason for us to doubt the quality of Samwha?
Few pictures I found are attached herewith.05.jpg
 

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madman29 said:
Yes the sound is very enjoyable and the highs are really nice. Tube amps are supposed to be warm sounding was my notion. But the very thing I like about this amplifier is the top end.
Will post a detailed 'how it sounds' review soon.
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As @jls001 pointed out the issue is fakes.
Believe me it's very difficult to source or even be sure what you are buying is fake or real
 
Hello Rikhav,

In Kolkata, there are few well known shops who are mainly suppliers of big contractors for Railway, Electric Supply or other government departments. In my experience, I have never received any Fake from them . Either they don't stock the item, but if they stock it, one can almost be sure of their genuineness.
And till date, I have yet to experience any fake Samwha in Calcutta. Maybe it doesn't make business sense to copy Samwha for it's price.

Regards
 
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