SX-Amp and NX-Amp

www.hifisonix.com
Joined 2003
Paid Member
Your amp will still work even if you do not match the transistors.

Just make sure you use the same gain grades in the complementary pairs.

Matching however will give you better distortion figures but not that much that it will ruin the sound of the amp.

I would therefore not spend 45 GPB on a transistor tester.

Balu's test set up can be done quickly and easily without spending a lot of money.
 
Disabled Account
Joined 2016
Thanks for the advice Bonsai

Just to confirm:

The following component pairs should be matched

Q8 and Q10 (diamond buffer transistors)
Q9 and Q11 (diamond level shifters)
Q6 and Q7 (TIS transistors)
D4 and D3 (10V Zener Regulators)

Just make sure you use the same gain grades in the complementary pairs.

Therefore the above listed are the complimentary pairs that you are referring to?

Thanks again :)
 
Disabled Account
Joined 2016
Hi Bonsai / Forum

Searching from RS (UK), for BC550C transistor [Mouser have them on backorder - factory lead time 6 weeks away], so, I have: BC550CG, BC550CBU, BC550C, BC550CTA on offer.

For BC560C: I have BC560CG or BC560CTA

Manufacturers on offer are ON Semi or Fairchild.

Not being fussy, instead, ignorant and eager to learn; how would I choose from these different parts please?

What specifications would help me choose between them?

Many thanks all :)
 
Hi guys, another quick question -- on the sx amp power supply, I notice that if I mount the rectifier at the bottom of the PCB as shown on p. 32, the positive leg of the rectifier goes into the negative leg, so the polarity of the whole supply goes the other way. Shouldn't the notched end face away from the edge of the PCB?

If I were to use a free-standing heatsink instead, would a 2.5" one work instead? Thanks in advance.
 
Hi guys, another quick question -- on the sx amp power supply, I notice that if I mount the rectifier at the bottom of the PCB as shown on p. 32, the positive leg of the rectifier goes into the negative leg, so the polarity of the whole supply goes the other way. Shouldn't the notched end face away from the edge of the PCB?

If I were to use a free-standing heatsink instead, would a 2.5" one work instead? Thanks in advance.
Why insert the rectifier from the wrong side of the PCB?
Surely it only makes sense to mount the rectifier on the correct side where as you have noticed , the lead outs line up with the correct pads !
 
Hi guys,
If the C6 & C9 capacitor recommended is unavailable are the Panasonic 22000uf 50v audio grade capacitors on eBay likely to be genuine and the right thing to use as a replacement?
Any help much appreciated,
Josh
Ebay retailers are very variable. From crooks to first class.
You need to assure yourself that the retailer you have chosen is honest and reliable and that their guarantee holds good if you need to complain that they have inadvertently supplied fake components.
 
Be careful and check what you receive.
One Member here almost went bankrupt when he organised a group buy that turned out to be very popular.
He bought thousands of faked jFETs and distributed them around the world without doing any component testing.
He had to recover all these fake devices because the seller would only reimburse on the basis of returned product. It seems the seller would not pay the return postage. Insist that your Retailer does pay return postage if they supply faulty or fake goods.
 
Hi guys,
two questions:
1- is there a problem if i used the Front end stages transistors (Q8-Q9-Q10-Q11) all BC546B /BC556B... i know they differ in Vceo but is it critical .
2- is there a problem if i omitted the SC protection(U1- R7- R2-J1) and used another power supply ( just for testing with a bench power supply and till ican get the FODM Opto?
 
Hi guys,
two questions:
1- is there a problem if i used the Front end stages transistors (Q8-Q9-Q10-Q11) all BC546B /BC556B... i know they differ in Vceo but is it critical .
2- is there a problem if i omitted the SC protection(U1- R7- R2-J1) and used another power supply ( just for testing with a bench power supply and till ican get the FODM Opto?
I think it is time someone redraw the sx pcb for smd input transistors.;)
Bc8xxc are common parts available everywhere.