Please send me the schematic, I think I can find out the way... basically to reduce the gain we can reduce input stage gain or increase the feedback etc,but it can be doneHello Friends,
I am bumping this thread again. I am thankful to the knowledgeable folks here. I enjoyed my set of TM 50 for a while and had put them aside. I was using Bogen AP-35, which has developed some issues, have put my TM 50s back into use.
Now that I have travelled some good distance in this hobby, I could realise that the noise floor of my TM 50 is much higher than the Bogen AP-35. I can’t expect same performance because TM 50s are basically built as PA Amps. However, I was wondering if there is a way, I can reduce this noise floor. They are too powerful for my Jensen P12N Alnico Speakers. I have to only turn 10% of the volume pot to reach full volume. I was told if I can reduce the ‘gain’ I can reduce the noise floor. I am ok with reducing the ‘power’ of the amp from 50W to say 20 W, but in return I will be happy with a lower noise floor.
I will be grateful for any ideas and thoughts on this. Thank you for your time.
Help needed to restore Ahuja TM 50
- Thread starter kvijay.svg
- Start date
hi i am looking for ahuja 100 w circuit if you have kindly share
reubensm
Well-Known Member
would you have the model number of the amp?
I have a broken "Arphi Super Series Free Field Amplifier" which is a 100W amp. It runs 4x6L6GC tubes and 5xECC83 tubes and has 3 transformers - I guess power, output and choke. Aux Selector has 4 positions-Mic4/Phono/Tape/Radio. 7 other pots are MIC-1/MIC-2/MIC2/MIC-4,AUX/MASTER/BASS/TREBLE. Power Switches are H.T-ON and FIL-ON. Can anyone please provide me with a circuit diagram for it.
I recently purchased two dead Ahuja TM-75 tube amplifiers and repaired, restored and recapped them and I should say I am pleasantly surprised with their clarity and soundstage. I have changed all electrolytes to Nichicon capacitors and ceramics to polyprophylene film capacitors. I have bypassed the tone controls to remove coloration added by the capacitors and am planning to mod the amplifiers by adding selectors for biasing of the ECC83 inputs for different tonal qualities. I would like to thank this thread and reubensm for the schematics without which I would never put my hand in them considering I have never worked on or heard a tube amp before. I also purchased a Bogen M120 amp and plan to convert it into a stereo amp alongwith the Arphi some time later.
VikasG0791
New Member
Do you have Ahuja TM30 and there input/Output Transformer layout/Winding schematic?
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kvijay.svg
Active Member
Hi, I do not have the ahuja tm30 schematic
VikasG0791
New Member
Ok, or what about Ahuja TM50 Amplifier Schematic?
And also need layout/Winding data of TM50 power/audio transformer.
kvijay.svg
Active Member
Hi I don't have the tm50 model schematic also. Sorry
@VikasG0791 the TM30 diagram is already there in the 4th attachment (View attachment 67865) that you replied to.
VikasG0791
New Member
Thanks for replying but I need Power and Audio Transformer Winding Data. (I have all parts in my collection except Power and Audio Transformer)
So want to wind it myself....
I think its better to rummage through old Ahuja amps and salvage their PTs and OPTs rather than spending time and money in building your own because Ahuja made pretty well built transformers, and you will notice that they have different model transformers for every model tube amp they produced.
Also I wonder why you require those items given that they rarely go bad, unless you have ideas to convert mono into stereo in which case again you would require only an additional OPT and not PT, one PT can power both sections. Only thing is that you will have to use drivers with impedance of half the value on that taps, meaning 16ohm drivers on 32ohm tap, 4ohm driver on 8ohm tap ...and so forth.
VikasG0791
New Member
As you know, I have all the spare parts, Accept PT and OPT transformers. I want to make some classic/vintage type amplifier for myself. For which I need PT and OPT transformers. Can you tell me the alternative parts/number/value of both PT and OPT transformers. Which are currently available. Using which I can make tube/valve amplifier for myself
VikasG0791
New Member
As you know, I have all the spare parts, Accept PT and OPT transformers. I want to make some classic/vintage type amplifier for myself. For which I need PT and OPT transformers. Can you tell me the alternative parts/number/value of both PT and OPT transformers. Which are currently available. Using which I can make tube/valve amplifier for myself
It already says on the ckt diagrams : OP632 and AP732 for the Ahuja TM30, and OP647 and AP759 for the Ahuja A50M.
But the numbers wont help because mostly they will be printed on the rolled hard paper on the upper end of the transformer on the PTs (not OPTs) and washed out by the efflux of time, unless the amps are very old with metal transformer casings which have numbers etched on them.
It would be greatly appreciated if anyone here has the scanned copies of the "Popular Amplifier Circuits Vol 2" and "Popular Amplifier Circuits Vol 4" by Gyan C Jain. I suspect those will hold the missing missing diagrams of Ahuja TM50, Ahuja A60M , Ahuja A100, Arphi etc.
reubensm
Well-Known Member
From my experience, the key component in a tube amplifier is the OP transformer. The quality of the OP is a critical factor in the overall sound performance.
A good example is from this video posted by Terry of D-lab electronics, albeit used in a guitar amplifier context. If you want to learn a lot about tube-electronics, his videos are a great source of info. I learnt so much from his various videos, especially with trouble shooting and DIY builds. For example, I learnt how to test a tube OP transfer by watching his videos. Not too may knew how to do it the right way.
From my experience with Ahuja OP transformers used in both their solid state and tube amplifiers, they tend to be very robust but are not very great on the frequency response range front.
From what I get Vikas is not building a HiFi or let alone a Single Ended amplifier and is researching Ahuja ckts for his project. It does not make monetary sense to use a Hifi OPT like Hammond or Melphi for such a project. He can buy 2 broken Ahuja amps for the price of one HiFi OPT.
Building a tube amp from scratch in itself is a big daunting task. Also there is the danger of lethal voltages for people who havent handled any. We have worked on CRT televisions and so can work on it but newbees cannot. Its always better to purchase broken amps cheap and restore them and then slowly convert them into Hifi at your leisure. I am doing just that.
reubensm
Well-Known Member
For EL84 or ECL82 SET enthusiasts on a budget, the old OP transformers salvaged from Philips radios are a treat.
Check out our special offers on Stereo Package & Bundles for all budget types.
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