"Bride of Zen" Pre Amp

[Subbu68]

Since TCI does not add any gain, to fully enjoy balanced level pre outs from unbalanced RCA, either we can use a high gain preamp or add an extra gain stage

Unbalanced preamp out > Tube gain stage > TCI > Balanced inputs on Power amp.

You have these interfaces which convert unbalanced to balanced and vice versa. Some of these are called direct injection boxes

https://www.amazon.in/Behringer-DI20-Professional-2-Channel-Splitter/dp/B000CCSWQA/ref=sr_1_10?crid=3AFHWEW0DZ1VE&keywords=behringer+ultra+di&qid=1651043879&sprefix=behringer+ultra+di%2Caps%2C186&sr=8-10

Some of them use high quality audio transfomers some use THAT chips.
Here is another one

Unbalanced to Balanced Converter - Plasma Music Limited

My TCI is an unbalanced to balanced converter with no gain so ideal for situations where the original signal is already +4dBu.

plasmamusic.com

THAT 12xx series of chips boast the best specs and have been widely adopted in the pro-audio world.

Balanced Input/Output Assembly Guide

Safety Precautions, Warranty, and Disclaimer Improper soldering and handling of electricity can cause serious injury and damage to your property. Read and understand the instructions below before beginning your project. Follow the instructions, build carefully, and use the appropriate tools...

www.diyrecordingequipment.com

TU 8500 of Elekit has it all i believe..there is a switch that toggles between 1.15X and 3.1X gain..then as you both wrote TCI or equivalent to convert to balanced and to ACA amp..

I came across some IC based circuits for the conversion..

Rajan thanks for the link to ACA 1.8 guide.

Treading into new waters. The kits have left Cincinnati. Keeping fingers crossed that they land in Dubai at least on Friday..else have to wait for Eid holidays to be over for customs to clear them..9. days holidays would go waste.

 

[kaushik]

Why use hinges

 

[mbhangui]

Why use hinges

The answer to that is in the very first post

 

[kaushik]

The answer to that is in the very first post

i gotit .
one enhancement you can add
aluminum plate cutlike vintage guitar amp plate.
Laser print in reverse transfer black text to it(avoiding screen print)
.
A few passes of clearcoat spray

 

[aniket8097]

I had very similar choices including easy accesa to hiraga boards. . Plus i also considerwd elekit models.

What swung the decision towards the ACA was simple

I had very high efficiency speakers.

Plsus wirh ACA, u can experiment between bridged mono, a balanced mono and parrell mono.


Good choice. Hope it will turn out to your expectations. Interesting to hear a tube owners perspectives on old school solid states.

I have built aca monoblocks with blameless class a pre amp. Pre causes bad low frequency. Did u compare aca with anything else?

 

[lifewater]

I have built aca monoblocks with blameless class a pre amp. Pre causes bad low frequency. Did u compare aca with anything else?

Hi I am surprised about your comment "Pre causes bad low frequency." can you please elaborate. I too am using the same pre and it is wonderful.

 

[rajan-]

I have built aca monoblocks with blameless class a pre amp. Pre causes bad low frequency. Did u compare aca with anything else?

Sorry, no experience with blameless pre. So far I tried ACA with 3 different inputs

1. Driven directly from my samsung s8 phone (just for testing) Stereo into RCA
2. Wayne / Pass Whammy head phone amp with RCA out.
3. BOZ dual mono preamp

I dont have a Musical Sub woofer (Yet... although I am pretty much set on a pair of REL Sub... soon)
My Horn speakers are pretty good, and may be covering all my requirements on the bass for the moment.. . I am not after earth shaking bass. my benchmark for bass is a good double bass performance.

The whammy ROCKS the house. Its very dynamic. And very enjoyable . Especially on classic rock. Eg. Led zeppelin, deep purple.. and so on.. you get the idea..

Note: I have an order for a discrete Opamp on the mail (Burson V6 classic) ... waiting for it...

BOZ is more delicate, and not taking away any power. If I want to listen to something like Blues, this is my goto..

ACA is very versatile, and so far had far far exceeded my expectation (AT THIS PRICE POINT) on my system,
where I have put a build of a modded Aleph J amp on hold...

Please note, I have very high efficiency Horn speakers... details are on

Full Range Horn & system build

its been a sometime that I have taken up the courage to build another one after my last system. This will be a 2 channel system including horns, Amps and preamps. My previous set up: incase anyone is interested. https://www.hifivision.com/threads/2-way-speaker-build-with-horns.61352/ Time...

www.hifivision.com

is this the end game audio for me ?
NO
I have a Looooong list of items in my roadmap, including a tube gain/buffer, a tascam DA-3000 , pair of REL subs etc etc...

If I were you, I would ponder on the below:

are your speakers capable to satisfy your pursuit of of bass ?

and..

1. what is my speaker driven by ACA, and what is the efficiency.
2. Am I happy with speaker / ACA combination.
3. Am I happy with my room setup
4. what am I comparing ACA against ? anything under 2K USD ? or higher ? (I am sure there are much better stuff out there, but at what price ?
5. source / recordings,...., do I like them on any other setup ?

trust your ears.
you are unique... your ears are unique...

try a good EQ.. dont listen to audiofools...

 

[rajan-]

The Pre amp blue LEDs were vert bright, too bright. I installed a cheap Pot 50K value in between, and turned it to max resistance. now the LED brightness looks better.

Changed some of the internal wirings.

Removed the external volume control and installed in inside the wooden cabinet. Now its a complete Pre-amp with its own built-in (remote) volume control.

I had disconnected the BOZ pre amp for some time for some planned mods, and was using my Whammy Head Phone amp as my stand-in pre-amp.

However good the Whammy is as a Headphone amp, it doesn't come close to the BOZ when it comes to Pre-amp duties. (No offence to Wayne Colburn, who is the pass labs designer) . IMHO its strength is a HP amplifier. however, the DIYaudio store says its a good line stage.

WHAMMY Headphone Amplifier Full Kit

DIY headphone amp WHAMMY Class-A headphone amplifier Wayne Colburn Pass Labs hifi hi-fi amplifiers make build fun high-performance Class-A DIY headphone amp firstwatt PCB Circuit board

diyaudiostore.com

This Pre-amp is a modded version of BOZ. Dual Mono , Cascode Circuit.

I think its the cascode operation which is making all the difference, its just stunning in power, articulation and bandwidth. the bass attack and top end is presented much better than my Whammy which got a Preout. Also tried an older NAD pre-amp and Pre-outs from a Yamaha AV receiver.

I think I will keep the Cascode BOZ as my preferred pre-amp for now.

delicate Jazz works on Drum high-hat is so clear, with natural decay. Unreal what a tangband full-range can do in a single driver horn.

The crack of snare drums made me literally jump, I thought my son who has an electronic drums, cranked up the volume in his practice room, and whacked it.


removed the tall Hifi rack and arranged everything on the New Low profile entertainment unit.

 

[GLKR HiFi DIYAudiophile]

For some time now, I had the Pre-amp sitting in a show box.

What I have is a modded design , which is a Cascode version of the BOZ.
(Courtesy, Gareth from Sydney)
I have listened to an original BOZ. This modded version takes the performance higher without taking any strengths of BOZ (IMHO)

Hello Rajan,
Wow looks great in the wooden box.
I'm really happy you are pleased with my BOZ Cascode PCBs.
Keep up the great DIY work.

Regards, Gareth Roberts
GLKR Hifi
DIYAudiophile

 

[GLKR HiFi DIYAudiophile]

Here is my original Bride of Zen Cascode i built years ago.