DIY preamp

Eagerly waiting for review.

Regards
Sachin

Wonder why @hydrovac is not posting his listening impressions.

Sorry to have kept you waiting so long. Though the initial session was with Capt Rajesh... I was listening to the preamp almost daily... at about 30 hours running time , was lazy and also busy with work to write my opinion.

This is a very fine-sounding preamp. I’d describe the predominant sonic characteristics as: quiet, smooth , and balanced. It didn't sound “tubey”, nor like a solid state amp. It sounded composed, and musical. Sonic details are abundant, soundtstage was excellent – and I felt immediately that this preamp could be the core of my system. There’s plenty of gain.

Did I say I loved the sound? Buying the kit was a no brainer – from almost the first minute after I fired it up, I knew I had to own it. Yes, there is great satisfaction – and fun – in building something and hearing it come alive. But with DD offerings, you can do so and also expect the sound to be outstanding too.

A great audio offering is more than just the sum of it’s parts. Now, I’m not going to ramble on ad nauseum about how the DD will rival other high-end preamps, at a fraction of the cost. It will, and does.
The case I’ll make is that in a market crowded with similar offerings, the pre offers excellent value... and offers superb, engaging performance. Importantly, it’s quiet, (with the CD player on pause and my ear pressed against the tweeter, the pre has a very, very slight buzz. The buzz can’t be heard at all from about 2 inches away). Will it be the last preamp you ever buy? It’s possible. Will you have fun building it and bringing it to life? I guarantee it.

I’ve owned many preamps over the years, both tube and solid-state (as well as passive). For me, the DD strikes an impressive balance of performance, usability, and low cost. The key point being, it’s a kit: if you think this sounds like a 15K preamp”, think again! A unit of this caliber, if assembled and warrantied by a respected audio house, would retail for 2-3 times that much. If you can build it, the value is off the charts.

Most highly recommended!

Gear used:
Marantz CD6003
Arcam Delta 270
DIY 300 watt power amp
Boston A26 BS
Ecosse The Baton IC
Moster 12 guage speaker cable

Finished Preamp images:
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hNMST4d.jpg


QijcIY5.jpg


WSrisTi.jpg


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Congratulations! You must be pretty excited about that... what were you comparing it with?
It must have been very exhausting sitting concentrated for this kind of review.

Can i have a listen... this weekend?
Looks nice and simple... I may try building one.
 
Thanks for the detailed review. Your build is excellent.

Congratulations! You must be pretty excited about that... what were you comparing it with?
It must have been very exhausting sitting concentrated for this kind of review.

Can i have a listen... this weekend?
Looks nice and simple... I may try building one.
It's very simple build. It comes as fully soldered board with PCB mounted pot.It has onboard power supply
You will only need to connect transformer and RCAs.

Regards
Sachin
 
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Thanks for the detailed review. Your build is excellent.

Regards
Sachin

Thanks!
I have a question @Sachin @Aniket...

I noticed that, It sounds rad at high volumes... however, at low volume a significant channel imbalance appears. The left channel becomes MUCH dimmer than the right. In fact Capt.Rajesh pointed out in the first session itself... the problem also flips sides if I swap the left and right speakers, so, it's not the speakers or speaker wires.

If I were to replace the vol pot what is my best bet... also considering I need more initial wiper sweep. I get my listening levels at 9'o clock position... can a 100K solve the issue?
 
Last edited:
Thanks!
I have a question @Sachin @Aniket...

I noticed that, It sounds rad at high volumes... however, at low volume a significant channel imbalance appears. The left channel becomes MUCH dimmer than the right. In fact Capt.Rajesh pointed out in the first session itself... the problem also flips sides if I swap the left and right speakers, so, it's not the speakers or speaker wires.

If I were to replace the vol pot what is my best bet... also considering I need more initial wiper sweep. I get my listening levels at 9'o clock position... can a 100K solves the issue?
There could be some issues with this specific volume pot. I think 100k, linear pot should be sufficient.

Regards
Sachin
 
There could be some issues with this specific volume pot. I think 100k, linear pot should be sufficient.

Regards
Sachin

Hmm... I guessed so, just wanted to share... nothing negative here.

To clear this, Aniketh messaged me saying that actually a 100K linear was to be installed in the first place, but due to non availability of the same couldn't do... and forgot to inform me about it.
Very soon he will be sending me an Alps Japan, 100K linear... isn't that great?

Will update after replacing the pot.

...

Interesting to know, how is sound compared to dcb1/B1 based on 3sk170 jfets?
Which can be technically better?

Do let me know how it compares to the B1 once yo built it.


@spirovious, @Pranjal
I wouldn't compare... but, it currently occupies the position of my B1... (no offence to anyone):)

...
 
Sachin, nice looking batch!
Guess this is the pot Aniket will be sending as replacement.

Has anyone else procured a module from the earlier batch...? if so, pl post your build log and listening impressions.


....
 
Sachin, nice looking batch!
Guess this is the pot Aniket will be sending as replacement.

Has anyone else procured a module from the earlier batch...? if so, pl post your build log and listening impressions.


....
Hi
Aniket will send you the same size Alps pot you currently have it your preamp. The new batch is having place for miniature Alps pot. Everything else remains same.

Regards
Sachin
 
Sachin, nice looking batch!
Guess this is the pot Aniket will be sending as replacement.

Has anyone else procured a module from the earlier batch...? if so, pl post your build log and listening impressions.


....
 
I have gone through the whole thread and found that no-one has asked the most important question. Correct me if I've missed anything.

What are the input and output impedance of this preamp?
 
I have gone through the whole thread and found that no-one has asked the most important question. Correct me if I've missed anything.

What are the input and output impedance of this preamp?

From another thread where this was earlier discussed this information was provided

Hi @haisaikat specifications as follow

- Discrete stereo preamp/headphone amp
- Input Impedance: 100kOhms
- max gain: 8dB
- max voltage output: 11V rms
- SNR: 115dB
- THD: <0.002% 20-20000Hz, Vo=5V rms
- Transformer required: 18-0-18V AC, 50VA
- Frequency response: 1-150000Hz(-3dB)
He has also designed a Class AB power amp for 75W and 120W version. @Aniket can provide you more details on this.

Regards
Sachin
 
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