Thomo said:
I turn it on via the plug socket, whilst performing "duck and cover" procedures. Then off, smell and touch parts, then back on to test voltages if all is cool and the only burning smell is the porridge I left on the hob.
I have taken a pic of two 15VA Nuvotem tx next to a KI tx. As you can see the height is identical its just the width thats more on the ki tx (same as 30VA tx). The two transformers have insulation sheets and the top plate. Total height is 62mm.
TX STACKED
Hope this helps
Brent
TX STACKED
Hope this helps
Brent
You'd never stack two KI transformers. It won't even nearly fit by the looks of that pic. And then there's the strut brace in the way! Side by side with extension wires might have to do Lee.
The part about the fire blanket was not serious btw, but I was asking because I read somewhere that the fixing bolt through the middle of a toroid can act as a ground loop or something like that. I am just wondering if there'll be any negative effects without it.
About the BG AC's, it's looking unlikely I'll be able to get the 6.8uF's not at the same price anyway. But I can still get the other values, 10uF etc. Just give me a bit of forewarning and I'll get some in.
Lee.
About the BG AC's, it's looking unlikely I'll be able to get the 6.8uF's not at the same price anyway. But I can still get the other values, 10uF etc. Just give me a bit of forewarning and I'll get some in.
Lee.
jimh0612 said:
I feel robbed - I got mine for £6.50. 😀
I paid (slightly) more for the service manual!
If you get one, let me know. I'll send you the PDF (gratis of course).
(I'll send it anyway if you want it.)
Thomo said:
This can happen when you bolt the toroid to the bottom of the case, but the top of the bolt touches the top of the chassis.
This is known as a 'shorted turn'. If you google around you'll find more.
Hi again,
I have exchanged the op-amps with LM4562, and I've installed diamond buffers instead of the original HDAM buffers.
http://www.sinigersky.com/images/Marantz-diamond-buffers-step1.jpg
http://www.sinigersky.com/images/Marantz-diamond-buffers-step2.jpg
The buffers come from Per-Anders Sj�0‹2str�0‹2m, http://sjostromaudio.com/_unsql/hifi/qrv05/index.html
I have tried to measure the performance of the original HDAM circuitry in-place, but I had problems feeding test signal to the input - it worked only with removed op-amps (the output of the opamp shunts the signal). But then, a lot of ripple was picked up by the JFETs, so the measurements were bad. But comparing the frequency response, the diamond buffers are better. Actually they had excellent performance, I was not able to measure any noise or distortion coming from them. Considering the very low output impedance, I find the diamond buffers very suitable for this application. The sound coming from the player is now crystal clear, I am very pleased with the results.
I have exchanged the op-amps with LM4562, and I've installed diamond buffers instead of the original HDAM buffers.
http://www.sinigersky.com/images/Marantz-diamond-buffers-step1.jpg
http://www.sinigersky.com/images/Marantz-diamond-buffers-step2.jpg
The buffers come from Per-Anders Sj�0‹2str�0‹2m, http://sjostromaudio.com/_unsql/hifi/qrv05/index.html
I have tried to measure the performance of the original HDAM circuitry in-place, but I had problems feeding test signal to the input - it worked only with removed op-amps (the output of the opamp shunts the signal). But then, a lot of ripple was picked up by the JFETs, so the measurements were bad. But comparing the frequency response, the diamond buffers are better. Actually they had excellent performance, I was not able to measure any noise or distortion coming from them. Considering the very low output impedance, I find the diamond buffers very suitable for this application. The sound coming from the player is now crystal clear, I am very pleased with the results.
Talking about buffers / output pcbs I have just received our discrete pcbs back from our pcb makers.
They are single channel jobbies, the early tests show a perfectly flat response curve up to 10Khz and drops of rapidly around 40Khz.
We have left the regs and caps off the pcb and also the output cap, this way you can choose the quality of these important components.
Here is a quick pic of both sides of the pcb next to a HDAM can.
DISCRETE PCB
Brent
They are single channel jobbies, the early tests show a perfectly flat response curve up to 10Khz and drops of rapidly around 40Khz.
We have left the regs and caps off the pcb and also the output cap, this way you can choose the quality of these important components.
Here is a quick pic of both sides of the pcb next to a HDAM can.
DISCRETE PCB
Brent
sinigersky,
Very good work, but do you want those op-amps in the signal path AND buffers? Credit to you for thinking yourself and not copying others' routes. I don't think anyone else has replaced the HDAM but left the op-amps in place.
Brent,
That looks lovely. Extremely compact and neat. Looks very well made. I hope there's plenty of interest from those who can't be bothered to (or just can't!) etch, drill and stuff their own pcbs.
Simon
Very good work, but do you want those op-amps in the signal path AND buffers? Credit to you for thinking yourself and not copying others' routes. I don't think anyone else has replaced the HDAM but left the op-amps in place.
Brent,
That looks lovely. Extremely compact and neat. Looks very well made. I hope there's plenty of interest from those who can't be bothered to (or just can't!) etch, drill and stuff their own pcbs.
Simon
At least I have done something new 🙂
For me, the diamond buffers are very transparent, so I don't think they harm. They should just separate the opamps from the capacitive influence of the cable (200 pF or more?).
On the other hand, I am not a fan of super simple op-amp-like designs like that output of rowemeister, because it surely has a lot more distortion than the LM4562's and you really "listen" to your power supply when omitting all current sources and cascodes in such a critical section.
For me, the diamond buffers are very transparent, so I don't think they harm. They should just separate the opamps from the capacitive influence of the cable (200 pF or more?).
On the other hand, I am not a fan of super simple op-amp-like designs like that output of rowemeister, because it surely has a lot more distortion than the LM4562's and you really "listen" to your power supply when omitting all current sources and cascodes in such a critical section.
It is true that this discrete output stage benefits from a good power supply.
How much do those diamond buffers cost? I could try them in my pre-amp just for education. And maybe even as an upgrade.
Simon
How much do those diamond buffers cost? I could try them in my pre-amp just for education. And maybe even as an upgrade.
Simon
Well, Per-Anders' designs are always with standard industry parts which are cheap! The PCB is the most expensive thing and it costs about 4-5 Euro per buffer. If you build your own version with BC550/560's etc. the parts would cost about 2-3 Euro (max) per channel. The SMD version requires patience, but it's not so complicated to build. I think I needed 1,5-2 hours for 4 diamond buffers.
I can't do SMD soldering, I'm not good enough yet. I'd only use those parts if they came pre-soldered.
Looking good Brent. Is it possible to get the boards without the smt resistors, so I could mount my own 0.1% tolerance ones?
Lee.
Lee.
TA!
Not really, I get them made up with them already fitted and having different batches will effect the price.
I have used 1% tol resistors. I tried 0.1% and 1% and found no difference between the two. Also they match the 1% caps.
I get them with no regs caps or output caps, this is where the options come in lol
Brent
Not really, I get them made up with them already fitted and having different batches will effect the price.
I have used 1% tol resistors. I tried 0.1% and 1% and found no difference between the two. Also they match the 1% caps.
I get them with no regs caps or output caps, this is where the options come in lol
Brent