It is a thing of beauty. Hopefully I’ll get it spinning tomorrow and I’ll post another photo to torment you.
I’m curious to compare it with my digital gear... I’m expecting less clarity but possibly more toe-tapping. Of course, the phono amp is an unknown.
Update: I’ve breadboarded the phono amp and it works (by which I mean no smoke). I started the turntable and put on the first LP on my stack: Rumours.
All seemed well until I lowered the needle and then the platter gradually slowed down. By the time the music began it was already half speed and quickly deteriorated into a groaning dirge.
All seemed well until I lowered the needle and then the platter gradually slowed down. By the time the music began it was already half speed and quickly deteriorated into a groaning dirge.
Update: I’ve breadboarded the phono amp and it works (by which I mean no smoke). I started the turntable and put on the first LP on my stack: Rumours.
All seemed well until I lowered the needle and then the platter gradually slowed down. By the time the music began it was already half speed and quickly deteriorated into a groaning dirge.
Have you replaced the drive belt yet?
Forgot to mention, When I took my original drive belt off, it had taken on the shape of the motor and platter pulleys, sort of a V shape, I replaced it with one of the new white rubber types.
Strange, I wonder if the motor has suffered from attic storage, huge temp and humidity swings, unless you have a proper insulated loft room, not like my dark dank loft !! Have you tried just letting the motor run with no load for a while, or can you stop it easily with your finger?
So, I suppose proper evaluation of the RIAA board will need to wait until you can get the Rega up and running.
It turns out the plastic pulley is loose on the motor spindle. I pulled it right off with little force. A drop of Superglue should fix it.
Enjoy life with LP's and Turntables: Handling Rega motor speed problem....it's turning slower and slower ....
Enjoy life with LP's and Turntables: Handling Rega motor speed problem....it's turning slower and slower ....
This thread has been way off topic for ages!
In order to try to get it back on topic, is there a general consensus that the Maplin amps are ultimately worth persevering with? I ask because I was given an unfinished pair of Maplin amps years ago and I am now considering either finishing them off and using them or selling them.
In order to try to get it back on topic, is there a general consensus that the Maplin amps are ultimately worth persevering with? I ask because I was given an unfinished pair of Maplin amps years ago and I am now considering either finishing them off and using them or selling them.
Hello .. great little amps that don't take up much space
I use the BK mosfet version as based on the same design ... but still find myself making these little amplifiers, with a good power supply they sound great. If you don't want them I will have them 🙂
I suppose its Nostalger as this was the 1st amplifier I made many years ago .. including the bridging modules that maplin made.
nice and easy to make ... as said I have just ordered another batch of boards but still waiting for them to arrive .. but very busy with my Stan Curtis class A amplifier currently and my k8011 Velleman valve amplifiers (please see other posts)
all the best
I use the BK mosfet version as based on the same design ... but still find myself making these little amplifiers, with a good power supply they sound great. If you don't want them I will have them 🙂
I suppose its Nostalger as this was the 1st amplifier I made many years ago .. including the bridging modules that maplin made.
nice and easy to make ... as said I have just ordered another batch of boards but still waiting for them to arrive .. but very busy with my Stan Curtis class A amplifier currently and my k8011 Velleman valve amplifiers (please see other posts)
all the best
Absolutely, I think you will be surprised how good these little amps can sound, although it may depend on what you intend using them for, Hi-Fi or something else.
If it's Hi-Fi you should consider either building them exactly as the original maplin article, OR follow the little tweaks and mods that other members have suggested which I have implemented with my amps, and also again if it's Hi-Fi go with a lower output voltage mains transformer with (30v 0 30v) secondaries, to give you +/- 42v rails.
Any original Electrolytic cap's are likely to be old now, so you should probably think about fitting new parts.
You are correct about the thread going off topic, perhaps traderbam and myself should relocate our Turntable / RIAA conversation to the appropriate sections 🙂
I have a couple of these amps and both have hum and seem a little unstable if the output transistors are touched by hand.
So I redesigned the amplifier:
1/ Constant current source on front end.
2/ Replace diode with a transistor in current mirror.
3/ Decouple front end with RC on both rails to stop output noise getting back into input.
4/ Changed second ltp feedback capacitors for slightly higher values.
However if your amps work fine I would leave well alone.
As others have said maybe replace electrolytics.
Aha, Glad you got that sorted.
I think that we should probably move our Turntable and RIAA conversations to the appropriate sections, as levistubby points out the thread has drifted somewhat off topic 🙂
Nah its OK, this is a most refreshing thread here! Traderbam is one of those "old" contributors I liked much when discovering old threads...one of few still being here.
Haha, It's certainly been a very interesting and informative thread from it's humble beginnings, with so much great input and suggestions from other far more experienced and knowledgeable members than myself.
I'm afraid I'm one of those people (probably due to my age) that it is hard to convince that newer and better designed stuff actually sounds better, I'm not striving for perfection, more like looking for the sound I knew so well back in the late 70's early 80's, it sounded good to me then and it still sounds good to me now, so as far as recommendations for these little amps goes, and to anyone who has a kit that has been sitting around for years and is wondering if they are worth building up I would absolutely say yes, give it a shot, after all, what's to lose, and they might be pleasantly surprised 🙂
On a side note, the maplin amps do sound far better than my Quad II setup, But...... I'm not blaming the Quads just yet, more like the 22 control unit, But it will be interesting to drive the quads with the Rod Elliot Pre amp ......... I'm going off topic again aren't I 😀
Thank you for this. I do appreciate it. Call me Brian. 😉
I've dipped in and out of diyaudio over the years. I think this is a nice little thread. It's focused on getting more connection with music from old equipment we are fond of, and not much else. 🙂
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Entirely Up to you; it's your thread. I'm sort of treating the turntable stuff as useful in-fill while we wait for you to audition your Maplin amp.
BTW I got the you-know-what working. The superglue did it. More soon...
Well I started a new thread here, so we can talk about RIAA Stuff, Might have to start another to discuss (you know what) I may well have to anyway when it comes to replacing the anti skate belt 😀
http://www.diyaudio.com/forums/analogue-source/313976-rod-elliot-pre-amp-power.html#post5224378
Thanks for the comments guys. I'll dig the half finished modules out of the loft and see what I've got. As I originally said, I was given the unfinished modules quite a while ago along with some other bits and pieces.
That should not happen with a stable amp. The original Maplin (Dave Goodman) grounding scheme is a culprit, as we've discussed, and belongs on your list. You'll notice that in the original Hitachi datasheet they've separated the input and output grounds in their example layout. Goodman went ahead and combined them, presumably to simplify the construction.
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Edit: Correction - Hitachi didn't separate the grounds. But they put the ground connection to the board at the output rather than running the high currents via the input pads. Not as good as separate grounds but better than the Maplin layout.
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