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Old 28th March 2012, 01:32 PM   #31
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Hi Owen,
I have heard a Sugden long ago and remember I liked it though I don't remember it as well as the Leak. That is because I had the Leak at my home for a few weeks. I must have a look at the Sugden A48 circuit . As you say, it might be interesting to try out a clone.
I don't have Quad speakers though I have heard several of them at various other people's houses. They are very nice though they don't go as low as I like.

I have some old Mission 701's that have a been 'upgraded' a bit. I have had several other speakers in my house which have been better in many ways but overall I kind of like the sound I am getting now. With a sub it sounds superb.
The only other speakers I like better are Open Baffles that I'm still toying with.
I also have the bookshelf Mission 780 and a Rogers GS-1. All my other speakers have been given away as I have no space in my present house.

Wonder if anyone else has done a Leak Delta 70 and Sugden A48 comparison ?
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Old 22nd September 2014, 10:18 AM   #32
bra is offline bra
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Have anybody foto of Leaks 70 driver pcb - top and copper side ?
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Old 22nd September 2014, 10:20 AM   #33
bra is offline bra
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I've found top side but I still need copper side.
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File Type: jpg Leak driver pcb.jpg (250.4 KB, 110 views)
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Old 22nd September 2014, 04:13 PM   #34
EssB is offline EssB  United Kingdom
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Quote:
Originally Posted by bra View Post
I've found top side but I still need copper side.
Here you go ..
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File Type: jpg ST70PA solder side B.JPG (780.3 KB, 94 views)
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Old 22nd September 2014, 04:29 PM   #35
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Thanks EssB. There is more than one fan out here.
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Old 22nd September 2014, 05:44 PM   #36
bra is offline bra
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Superrrr, thank You !!!
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Old 15th November 2014, 02:20 PM   #37
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I see that the Leak Stereo 70 driver transistors look like the same package as Quad 303 drivers. Are they the same transistors? The reason for asking is that I have an odd replacement driver in a Quad 303, and I have a spare 70 plug in board.
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Old 15th November 2014, 02:51 PM   #38
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Hmm......the Delta70 surfaces again. This morning I came across the board that I had made . As I said earlier it isn't a direct clone as it uses different transistors and resistor values and a few circuit modifications. It sounds nice but possibly not very 'accurate'. Newer designs are better at transients and have better bass control. However I must fire it up again and see how it sounds against what I am using today. Should be interesting.
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Old 15th November 2014, 04:46 PM   #39
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That is TO5 package driver transistors. They don't make those anymore, and the pin compatible TO126 plastic package is also very rare. I've been using TO220 tranistors like TIP31C and TIP32C instead of TO5 transistors, but you have to twist the leads around because TO220 is B,C,E and TO126 is E-B-C.
The good news is that TO220 is easy to make a heat sink for, just cut a smidge of aluminum door frame and drill a hole in it. The tab is C, so don't let a heat sink touch anything, or use a mica insulator kit.
Ashok, the biggest sonic limitation on a Leak 70 was probably the original output transistors. Real 5 digit RCA transistors were selected from the 2N3055 process for more Vceo (or less leakage current at test voltage), but they had Ft of maybe 200 khz, which was probably audibly slow. I've used NTE60 output transistors instead, (on a copy of the Leak) which are probable MJ15003 copies, and the faster Ft cleans up the sound some IMHO. See the simulations someone did on Leak Stereo 70 with 2n3055, TIP3055, and something else.
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Last edited by indianajo; 15th November 2014 at 04:51 PM.
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Old 15th November 2014, 06:16 PM   #40
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Originally Posted by indianajo View Post
That is TO5 package driver transistors. They don't make those anymore, and the pin compatible TO126 plastic package is also very rare. I've been using TO220 tranistors like TIP31C and TIP32C instead of TO5 transistors, but you have to twist the leads around because TO220 is B,C,E and TO126 is E-B-C.
The good news is that TO220 is easy to make a heat sink for, just cut a smidge of aluminum door frame and drill a hole in it. The tab is C, so don't let a heat sink touch anything, or use a mica insulator kit.
Ashok, the biggest sonic limitation on a Leak 70 was probably the original output transistors. Real 5 digit RCA transistors were selected from the 2N3055 process for more Vceo (or less leakage current at test voltage), but they had Ft of maybe 200 khz, which was probably audibly slow. I've used NTE60 output transistors instead, (on a copy of the Leak) which are probable MJ15003 copies, and the faster Ft cleans up the sound some IMHO. See the simulations someone did on Leak Stereo 70 with 2n3055, TIP3055, and something else.
This is helpful, but can the Leak Stereo 70 driver transistors be used in a Quad 303? It looks like the collector emitter voltage is OK, but I,m no expert.
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