It's a replacement amplifier query and not really something I feel at all confident about building.
My old faithful Kenwood L-07M monoblocks are on the way out. One is still OK but the other is pulsing and sounds awful.
I have to add that despite their age these were the best amplifiers I personally have ever listened to.
Looking for a new amplifier how important is bandwidth in selectiing something as a replacement?
Using a couple of dirt cheap Fosi Audio in the short term and they sound like crap but my audio budget is a bit limited as I have splurged on a set of drivers for a new project.
Looking at sales sites very few makers are stating what their bandwidth is on retailers pages, Rotel being one of the few I have found. So are the new Rotel amps any better than the older models as far as speed and bandwidth go as they are just within my budget.
I don't need a lot of power as these would just be for the tops on my system in the loungeroom and the bottom ends are covered by Rotel already but quite old models the RB1070
My old faithful Kenwood L-07M monoblocks are on the way out. One is still OK but the other is pulsing and sounds awful.
I have to add that despite their age these were the best amplifiers I personally have ever listened to.
Looking for a new amplifier how important is bandwidth in selectiing something as a replacement?
Using a couple of dirt cheap Fosi Audio in the short term and they sound like crap but my audio budget is a bit limited as I have splurged on a set of drivers for a new project.
Looking at sales sites very few makers are stating what their bandwidth is on retailers pages, Rotel being one of the few I have found. So are the new Rotel amps any better than the older models as far as speed and bandwidth go as they are just within my budget.
I don't need a lot of power as these would just be for the tops on my system in the loungeroom and the bottom ends are covered by Rotel already but quite old models the RB1070
Why not invest the money in getting them fixed instead? Likely they need at least a recap at this point and probably more.
Mainly because the only feller in Australia who was supposedly competent at working on these doesn't seem to be around any more. RestorerJohn over at ASR hasn't replied to any of my messages and I don't know if he is still around. Nobody local wants to even open them up and have a look.
I'd love to get them fixed. I bought them from him over twenty years ago and have been solid until now
I'd love to get them fixed. I bought them from him over twenty years ago and have been solid until now
Fingers crossed, I hope you can find someone to sort them out.
I have heard good things about the Technics R1000 integrated, but the price is more than slightly breathtaking. (I have not heard one recently)
I have heard good things about the Technics R1000 integrated, but the price is more than slightly breathtaking. (I have not heard one recently)
Do it yourself and enjoy the satisfaction of having done it! 🙂
It's not rocket science. Watch youtube videos. You're looking at less than $50 worth of parts.
It's not rocket science. Watch youtube videos. You're looking at less than $50 worth of parts.
I can only wish that were true. I guess you've never looked at the innards of an L-07M, I wouldn't even know where to start on a diagnosis and I don't own any of the gear such as an oscilloscope
@restorer-john pops in here too. I'm pretty sure he's still around. I seem to recall participating in a thread with him maybe two weeks ago.
Tom
Well now I have, thanks to google! Looks pretty straightforward. It's not a Krell (nor a Halcro, since you're in Australia 🙂)
Since you've got one working amp and one non-working one, you're ahead of the game: Compare the two units, look for what measures different in the non-working one, and replace defective components. Heavens know I'm not one of those recap fetishists, but realistically you probably do need a full recap at this point in time, so the so-called shotgun approach is not inappropriate.
A good DMM is likely all you need, it's unlikely you'll need a scope.
Hi, the repair will likely be more expensive than, for example, one of the known good Fosi types with TPA3255. Sure there must be something very good & affordable between repair and dirt cheap stuff.
Experience with 1980 amplifiers is that many things need replacement. Often parts that are obsolete.
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I'd not call these FOSi good even at the best of times but I did buy at the budget end. Good value for my grandkids but not really high quality
Exactly as I meant. It is a brand producing high quality types too but you did not buy one of those.
Anyway, I used to do repairs of old electronics but things have changed after covid as costs of parts at distributors have become pretty high (and they are still going up). You can check this by making a list of all electrolytic caps, bridge rectifiers and the output relay and make a shopping list at a distributor. This is the minimum that needs to be done. Special attention for the 4 pieces 18,000 µF 71V (in 2025 18,000/22,000 µF 75/80V) filter caps. Check physical dimensions as caps have become smaller last decades. If semis are shot you will have a problem.
Chances are that you want to try a TPA3255 based amplifer like the Fosi ZA3 😀
Anyway, I used to do repairs of old electronics but things have changed after covid as costs of parts at distributors have become pretty high (and they are still going up). You can check this by making a list of all electrolytic caps, bridge rectifiers and the output relay and make a shopping list at a distributor. This is the minimum that needs to be done. Special attention for the 4 pieces 18,000 µF 71V (in 2025 18,000/22,000 µF 75/80V) filter caps. Check physical dimensions as caps have become smaller last decades. If semis are shot you will have a problem.
Chances are that you want to try a TPA3255 based amplifer like the Fosi ZA3 😀
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A few years ago, I sold my last set of original (07m) output devices (set of 6), but most of the other original transistors I still have, or can still get.
They are a finicky but excellent amplifier. Tested at 190W continuous at 8R and 290W@4R. Ruler flat response. Non magnetic aluminium casework, chimney heat-sinks, auxiliary transformer for trigger on/off etc.