Q17 - an audiophile approach to perfect sound

Jump to Latest
E

ed linssen

Member
Joined 2004
iTiberius

iTiberius

Member
Joined 2005
bloqhed said:
Thanks Tibi, I plan to order soon. I notice that KSC1845FTA and BS250P are on backorder with long lead times, are there alternate parts?
Click to expand...
I have updated documentation on GitHub. Here is a copy/paste:

Selecting alternative parts
With current component shortage, it may happen that some parts listed in BOM to be unavailable, here are few alternative recommendations:
R16 - use a metal film resistor
C7 - use a good polypropylene made by Mundorf, Epcos, Vishay, CDC,
U1 - following opamps can be used and will offer different sonic signatures: LME49710, LME49990, OPA604, OPA134, NE5534. Do not use TL071, TL081, LM301, LM741.
Q2 and Q3 - use transistors with Vce >= 65V & hFE>=100 : 2N5401 / 2N5550
Q7 and Q12 - other transistors that may be used are: KSC1845, 2N4401, BC546 / BC547 / BC548 / BC549 / BC550 - use the one with A termination for Q7 and C termination for Q12.
C1 - this must be silver-mica or at least polystyrene.
Q1- KSA992, 2N4403, BC556C, BC557C, BC558C, BC559C, and BC560C
C10 - silver-mica or ceramic NP0
R26, R27, R28 - these must be non-inductive resistors. MILLS make some good ones.
C17 - in this order: polystyrene, teflon, foil polypropilene, metalised polypropylene.
Q5 and Q6 - following pair replacements may be used with excellent performance: FQP3P50/FQP4N80; FQP4P40/FQP5N60
Q15,Q16,Q17,Q18 - following pairs can be used with modest performance IRFP9240/IRFP240; 2SJ201/2SK1530; 2SJ118/2SK413; 2SJ119/2SK414.

Instead BS250 you may use ZVP3306A

When you use any replacement, please take care on part pinout.


Regards,
Tibi
 
Last edited by a moderator:
  • Like
Reactions: 1 user
chickadee

chickadee

Member
Joined 2021
tvicol said:
Hi Ed,

It will perform better ? For sure, Yes.
It will sound better ? Maybe, because depends on your source, your cabling, your room etc.
Adding more output devices will decrease amplifier output impedance and therefore increase amplifier capability to deliver more current in a low impedance.
Adding more output devices will make amplifier "more powerful" at lower impedances and increase his capability to drive complex audiophile speakers , including ESL.
For example at same +/-50V and 1KHz, an amplifier (here I do not talk about Q17) may have:
1. With one pair
- 100W in 8ohm
- 120W in 4 ohm
- 120W in 2 ohm

2. With two pairs
- 100W in 8ohm
- 180W in 4ohm
- 300W in 2 ohm

Having an amplifier with very low output impedance make sense even you have small bookshelf speakers.
Q17 achieve this by using high transconductance mosfets. One pair already drive a wide range of speakers very well. Two pairs is for audiophiles who look for the best at given price.


Regards,
Tibi
Click to expand...
Tibi,
What is the maximum power that can be obtained from this amplifier, in a bridge connection at a supply voltage of +-50 volts (speakers of 4 ohms)? Of course, in this case, two pairs of output transistors are used.
 
J

julienfesty

Member
Joined 2010
Hey there, i am planning on building my first amp and this seems to be a nice project. I have heard once the original and was quite impressed, so i can't wait to listen this little beast !
Approximately, How much would it cost for the total project, psu/main board and an enclosure ?
Also, i cannot find the link for the mouser psu project buying list !
 
iTiberius

iTiberius

Member
Joined 2005
The best way is to order transformer directly at manufacturer.
For my projects I order at https://petra-toroid.ro/?lang=en they ship worldwide.
How to order:
  • go to https://petra-toroid.ro/contact/?lang=en use form or email
  • mention that you want to order one or two 300VA trafo
  • primary 115Vac or 230Vac, depending on the mains voltage in your region
  • 2 separate 36Vac secondaries
  • optional magnetic shielding
  • mention that application will be for audio


If your mains are 220-240Vac, you may order a trafo here https://www.audiophonics.fr/en/toroidal-transformers/toroidal-transformer-300va-2x38v-p-5548.html

Regards,
Tibi
 
  • Like
Reactions: 1 user
iTiberius

iTiberius

Member
Joined 2005
Yes, you need to multiple the order with the number of boards. On mouser page see top right corner. For 12+1 multichannel you need 13. :cool:
Screenshot 2022-05-27 at 08.09.44.png


For other documents check your mail.

Regards,
Tibi
 
  • Like
Reactions: 1 user
You must log in or register to reply here.
Top Bottom