Q17 - an audiophile approach to perfect sound

[Chazz]

Yes C7 need to be of good quality. Look in the start of this thread. They are discussed there.

Kind Regards

 

[Chazz]

Stef ,
In the past I did get a tip from Hugh Dean ( Aspen Amps ) regarding the use of FQA/PF and IXTQ power FETs .
Solder a 470p and 47R resistor between drain and gate to avoid future problems which could happen due the high transduction of those FETs .
This way you slow them down a bit and protect too for the use in amps .

This is good info. Have had those problems. Do you mean i parralel or series?

 

[stef1777]

Hello,

I have already tried this. It causes an oscillation (= high consumption on the power supply).

It works well without so why add things.

Stef.

 

[meanman1964]

Stef ,
If you had test this already than it's okay . Just a thought .

 

[stef1777]

Hello,

I was able to run the Q17-Mini through the QuantAsylum test bench.

On 8R load with -10dB input and the 1.2V sensibility config.

Stef.

 

[Chazz]

Looks Really good. Do you mind posting a picture of your test setup?

Kind Regards

 

[stef1777]

Hello,

The configuration is very simple.

• One BNC-RCA 1m cable for the output.
• One 2xBNC-RCA differential 1m cable for the input (to avoid ground loop).
• Two BNC-BNC 15cm cables for the interconnection of the second channel.
• A 100W 8 Ohm load.

The 2 x BNC-RCA differential cable can be bought directly on eBay. For stereo testing, you need 2 BNC-RCA cables, 2 2xBNC-RCA cables and 2 loads.

Regards,

Stef.

 

[Chazz]

Thank You

Have now ordered the cables you recommend.

Really love the mini. Use it as my main amplifier.

 

[meanman1964]

Stef ,
In the Mouser BOM Q2 is a KSA992FBTA . Can a FTA type also be used ?

 

[thimios]

Look here,same transistor, different packing bag

 

[meanman1964]

I know , bud is there a reason for taking the FBTA . Only different I see is the highest hfe of the FBTA . Is it for this Stef is taking that one ?

 

[asuslover]

Same transistors.

 

[radu19880625]

Hello everyone! I am planning to embark on building a pair of Turbo units.

Do you have any suggestions on what parts should be checked for tight tolerance or matched?

Many thanks!

 

[meanman1964]

Hi!

A pair of Vishay 100V mosfet.

Q1': SI2328DS
Q4': SI2325DS

With the SMD parts and 60V rails, zeners D2 and D4 MUST BE REPLACED by 16V 1N5246B zener to get 14V.

With the SMD parts, we get -3dB more on the 50Hz rejection.

I replaced Q6 with FQPF3N80C. With the Toshiba I got burst of oscillation > 32V. With the FQPF3N80C it's ok until the clip à 35V.

Stef.

Stef ,don't you mean D3 instead of D4 ?

 

[stef1777]

Oops, you're right.

I 've updated the doc.

https://github.com/stefaweb/Q17-Amplifier/blob/main/Q17-Mini-3.0/Q17-Mini-SMD-BOM.md

Regards,

Stef.

 

[meanman1964]

Stef , can I use a 2 x 45Vdc toroid for the Turbo ?

 

[stef1777]

45Vac is too high.

45Vac is 45 x 1.44 = 63Vdc peak

I'd say 43/44Vac is the maximum. There's little point in powering it too high. It won't add any power and will degrade the SNR.

@radu19880625: The output mosfets should be sorted as well as the BS250s (unless you use an NDC7003P instead).

Regards,

Stef.

 

[meanman1964]

What's the minimum rail voltage ?

 

[stef1777]

56Vdc

Stef.

 

[birdbox]

Anyone in the USA have an extra set of V3 mini boards to sell?