yairf
Trade: Teddy Pardo Audio
Hi all
The legend has it that once upon a time in the previous century, Ivor Tiefenbrun, met with his then best mate, Julian Vereker, and handed him a document containing a list of drawbacks that Linn engineers found on Naim's amp design. The list included:
- No front-end regulation (resulting in audible noise-floor).
- Asymmetrical input stage (resulting in increased distortion).
- Inherent tendency to oscillate (resulting in blown tweeters).
- the preamps are based on mechanical switches and knobs, which tend to lose contact after some years.
As the legend has it, Julian kicked his friend out of the door, suggesting him to focus his efforts on designing speakers and turntables.
They say that at this point in time (1985), Ivor decided to introduce amplifiers under the Linn badge.
The older-generation (non-chip) Linn amps are pretty similar to the Naim design, with some modifications as per the above list.
I have seen very little views on Linn amps on PFM, most of them were not extremely warmhearted. It seems that Linn amps are always describes as "Lean", "Dry" and so forth.
A while ago, I gave a close look at the LK-100. It's a very nice piece of equipment, typically available on ebay for 250 UKP - almost half the price of its counterpart - the NAP-140, and with some small and simple changes, it can be made equal, or better than the 140.
For a start, the LK-100 has a very good build quality, aided by a nice trafo and good choice of components. In addition, its extremely easy to dismantle (good news for bodgers), and there is no limit to the mods you can apply to it.
See the schematic below:
Note the following changes. Start with those I consider to be mandatory:
1. C201 - the input stage low-pass filter, set to 2.2nF - about 8-10 times the normal values we come across ! no wonder the thing has no highs !!
Change it to 390pF, even 470pF will be fine to restore high frequencies.
2. Feedback loop: the feedback resistors are extremely small - while Naim has 27K--1K resistors, the LK-100 has 3.9K -- 150R, which is actually a good thing. However, the feedback cap is only 122uF - no wonder the LK-100 has no bass !
I actually prefer the lower-valued resistors as-per Linn, however, the feedback cap MUST be replaced to something in the range of 1000uF - use a good 'lytic bypassed with a decent Poly cap and you should be fine.
In addition:
1. The main caps are OK, and you can leave them, I usually replace them with Mundorf M-Lytic - the height of the chassis limits cap choice to 10,000uF, which is just fine.
2. The front-end regulation is implemented with a bog-standard zener-transistor arrangement. You can always replace it with your best choice of regs.
The result - the LK-100 has now restored its lost "oomph", and it really kicks butt! It can deliver plenty of drama to demanding speakers without introducing its own drama - it is extremely quiet and smooth.
Given its ridiculous selling price, I think it's really a star candidate !
Cheers, Yair
The legend has it that once upon a time in the previous century, Ivor Tiefenbrun, met with his then best mate, Julian Vereker, and handed him a document containing a list of drawbacks that Linn engineers found on Naim's amp design. The list included:
- No front-end regulation (resulting in audible noise-floor).
- Asymmetrical input stage (resulting in increased distortion).
- Inherent tendency to oscillate (resulting in blown tweeters).
- the preamps are based on mechanical switches and knobs, which tend to lose contact after some years.
As the legend has it, Julian kicked his friend out of the door, suggesting him to focus his efforts on designing speakers and turntables.
They say that at this point in time (1985), Ivor decided to introduce amplifiers under the Linn badge.
The older-generation (non-chip) Linn amps are pretty similar to the Naim design, with some modifications as per the above list.
I have seen very little views on Linn amps on PFM, most of them were not extremely warmhearted. It seems that Linn amps are always describes as "Lean", "Dry" and so forth.
A while ago, I gave a close look at the LK-100. It's a very nice piece of equipment, typically available on ebay for 250 UKP - almost half the price of its counterpart - the NAP-140, and with some small and simple changes, it can be made equal, or better than the 140.
For a start, the LK-100 has a very good build quality, aided by a nice trafo and good choice of components. In addition, its extremely easy to dismantle (good news for bodgers), and there is no limit to the mods you can apply to it.
See the schematic below:
Note the following changes. Start with those I consider to be mandatory:
1. C201 - the input stage low-pass filter, set to 2.2nF - about 8-10 times the normal values we come across ! no wonder the thing has no highs !!
Change it to 390pF, even 470pF will be fine to restore high frequencies.
2. Feedback loop: the feedback resistors are extremely small - while Naim has 27K--1K resistors, the LK-100 has 3.9K -- 150R, which is actually a good thing. However, the feedback cap is only 122uF - no wonder the LK-100 has no bass !
I actually prefer the lower-valued resistors as-per Linn, however, the feedback cap MUST be replaced to something in the range of 1000uF - use a good 'lytic bypassed with a decent Poly cap and you should be fine.
In addition:
1. The main caps are OK, and you can leave them, I usually replace them with Mundorf M-Lytic - the height of the chassis limits cap choice to 10,000uF, which is just fine.
2. The front-end regulation is implemented with a bog-standard zener-transistor arrangement. You can always replace it with your best choice of regs.
The result - the LK-100 has now restored its lost "oomph", and it really kicks butt! It can deliver plenty of drama to demanding speakers without introducing its own drama - it is extremely quiet and smooth.
Given its ridiculous selling price, I think it's really a star candidate !
Cheers, Yair