Anyone building a pearl phono soon?

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Panelhead

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Joined 2002
mattjk said:
I'm kicking myself for not ordering the Q pack earlier. Does anyone want to split an order and match them, or anyone have a q pack for sale?

Thanks,
matt
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Matt,
The parts in the Q pack were not matched up anyway. The 170's and the 389's were just provided.
Order the parts from www.mcminone.com They are plenty cheap and in stock. Order three times as many as you need.
The cascode transistors can be matched up for beta.
I have started matching the fets by measuring on resistance. Using a VOM connect source to drain and allow it to settle for a minute. The on resistance will drop for a period and stop.
This is not a real match, but it helps in bias current. In a circuit like the Pearl where 4 170's are paralleled having the same current through each can only help improve the sound.
The 389's are a little harder to measure, but should be close from one side to the other. The pair in my Q- pack were off by more than 50% in current draw. I just clipped out the lower current one and inserted a new one until the currents were about the same.
I think the parts with lower on resistance, or higher current draw are better in the circuit.
Good Luck!

George
 
Sandy H.

Sandy H.

Member
Joined 2002
TUFSolutions.com
Not trying to cloud the issue, but in the following thread:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=42456&highlight=

A member bought a bunch from Pacific Micro for $.39 each. It appears that MCM is a little more 'proud' of their stock at 8 times the price! Please correct me if I either mis-read the thread or got a bad price on MCM or something.

I too am sourcing the parts, as I hope to build mine this month and also let the Q packs from Pass expire. If someone finds a source that is closer to Pacific than MCM in price, please post it here.

Sandy.
 
P

Panelhead

Member
Joined 2002
Sandy H. said:
Not trying to cloud the issue, but in the following thread:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=42456&highlight=

A member bought a bunch from Pacific Micro for $.39 each. It appears that MCM is a little more 'proud' of their stock at 8 times the price! Please correct me if I either mis-read the thread or got a bad price on MCM or something.

I too am sourcing the parts, as I hope to build mine this month and also let the Q packs from Pass expire. If someone finds a source that is closer to Pacific than MCM in price, please post it here.

Sandy.
Click to expand...

I have never ordered from Pacific, but the unit price from MCM for quanties to 10 or more is 79 cents. This is for the 2SK170 listed in the thread linked.
Next time I need a bunch of transistors I will try Pacific Micro. Saving money on transistors leaves more for caps and chokes.

George
 
Sandy H.

Sandy H.

Member
Joined 2002
TUFSolutions.com
Thanks for the correction. I'm not that savvy with the nuances of transistors and searched for 2SK170BL, not the 2SK170. For sure, the 2SK170 is much closer to the price and the fact that we can buy it piece by piece is much better than a quantity order.

I've got an RFQ in to 4starelectronics for the BL version and once I get the minimum order qty/price, I'll post that in case its a better deal or if it makes it worth while to buy a quantity and distribute to interested users.

Thanks for double-checking!

Sandy.
 
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Ori

Member
Joined 2004
Matching transistors

First, try to get transistors from the same production lot for best matching. I built a small circuit on a plug-in prototyping board to measure the zero volt (input) Idss on a 22 ohm source resistor.
This is not a perfect match but it's good enough. True dynamic matching is just too complicated for most DIY'ers.
 
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