• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Mullard 44 Integrated Stereo Amplifier

M

Musa Zahid

New Member
Dear All,

I just bought Mullard 44 single ended EL84 tubed amplifier it was not working when i bought however i went to a technician while checking one of its output transformer was blown . I need help on this either i get the original transformer repaired again but i am not having its output transformer specifications. If anyone has it please share. Second option is i get new Chinese transformers from aliexpress to do the replacement.

1743676881272.png
1743676897941.png

If anyone is having its output transformer details please share so i can get this beauty back to life again.

Regards,
Musa Zahid
 
Register to hide this ad
5K seems to be pretty standard for an EL-84 SE amp. I used a couple of those $17 Chinese OPT's in a EL84 SEP build. They sound decent.
You also might look at the thread on getting all you can out of the Magnavox 8600.
It's a long thread, but there are other transformers that people have used.
Those small Edcore's without end bells, a few that were used in guitar amps, etc.

Magnavox Flea Power: Getting More Out Of The 8600 Series - A Lot More!

Moderator's note: an excellent Table of Contents to help navigate this exceptional thread has been compiled and is available here: https://audiokarma.org/forums/index.php?threads/table-of-contents-for-magnavox-flea-power-getting-more-out-of-the-8600-series-a-lot-more.1097653/ So much has...
audiokarma.org
But if your going to buy the ones from China, get 'um before the tarrifs kick in. :biggrin:
 
I'd get a second opinion.
Output transformers don't just blow up.
Check to make sure yourself, or get a different technical on the job.
I'd hesitate to buy anything modern because the audio transformers being made now days aren't really great like they were when this was made.
You could also camp ebay and wait for another correct transformer to show up and buy that if it's determined that your transformer is actually failed.
 
I built SE 6V6 amps using an MPS (Musical Power Supplies) output. It measures great and sounds really good too. Two friends were so impressed they built this amp as well. Hard to say if the footprint would fit.

It's his p/n OT10SE-HF-USA, 5k with 4/8 ohm secondaries. A little over $50 US each which I think is a decent price for a good performing output. It has good -3dB 1W bandwidth from below 20Hz to 50+kHz.

Musa, where are you located? That might/will affect which options are good for you.
 
nerdorama said:
I built SE 6V6 amps using an MPS (Musical Power Supplies) output. It measures great and sounds really good too. Two friends were so impressed they built this amp as well. Hard to say if the footprint would fit.

It's his p/n OT10SE-HF-USA, 5k with 4/8 ohm secondaries. A little over $50 US each which I think is a decent price for a good performing output. It has good -3dB 1W bandwidth from below 20Hz to 50+kHz.

Musa, where are you located? That might/will affect which options are good for you.
Click to expand...
+1 on musical power supplies. good stuff.
 
As noted above, the transformers should have a 5KΩ primary. If you don't need multiple secondaries, the transformers from the old Akai reel decks (Terrecorder, M7 and M8) are excellent for this. I built a small SEP amp with those years ago and am still using it for headphones almost two decades later. The output impedance of the transformers is 8Ω. If it would be helpful, I could measure one of these to see how well they might fit in your amp. I would strongly recommend replacing both transformers at the same time and not using Chinese parts.

Jack
 
yeah you really should match them, and non-originals in a feedback amplifier are going to need some tuning.

I will say the extremely cheap Chinese ones I used on an SE 6bq5 amp are better than I'd have ever imagined them to be. Not the finest things on the planet I'm sure but for for very small money in the physical size I needed them to be I have zero complaints.

If the transformer is being re-wound, the place doing the work should be able to figure out what exactly they were when they un-wind them in order to figure out the construction. I'd be pretty surprised if its not very near a 5K primary though.
 
trainbuffton said:
I'd get a second opinion.
Output transformers don't just blow up.
Check to make sure yourself, or get a different technical on the job.
I'd hesitate to buy anything modern because the audio transformers being made now days aren't really great like they were when this was made.
You could also camp ebay and wait for another correct transformer to show up and buy that if it's determined that your transformer is actually failed.
Click to expand...
Someone may have cranked the volume and the blown transformer wasn't connected to a load?
 
bum coupling cap causing excessive curent flow can do it too. Not the most common thing to have fail in an amp to be sure but I just finished a rebuild on one last night that had an open primary for unknown reasons. It happens.
 
+1 to the recommendation that you get a second opinion on whether the output transformer was blown. This is unusual and a bad error for a tech! By the way your amp is quite a rare example of a stereo version of the Mullard 3-3 circuit. I followed the assembly manual when I build an amp like this. It is a collectors' item and would be quite valuable even with one faulty transformer, so please don't let any other tech hack up the chassis!
 
Thank you everyoneits great to hear from all of you I will get the transformers checked today from an expert then will get the board fixed as per schemetics then will give it a try again i hope it works . Will get the transformer varnished again .
 
trainbuffton said:
I'd get a second opinion.
Output transformers don't just blow up.
Check to make sure yourself, or get a different technical on the job.
I'd hesitate to buy anything modern because the audio transformers being made now days aren't really great like they were when this was made.
You could also camp ebay and wait for another correct transformer to show up and buy that if it's determined that your transformer is actually failed.
Click to expand...
i agree with you as chinese tubes dont really sound like tube they sound rounded muffled the equipment is compromised.
 
gadget73 said:
yeah you really should match them, and non-originals in a feedback amplifier are going to need some tuning.

I will say the extremely cheap Chinese ones I used on an SE 6bq5 amp are better than I'd have ever imagined them to be. Not the finest things on the planet I'm sure but for for very small money in the physical size I needed them to be I have zero complaints.

If the transformer is being re-wound, the place doing the work should be able to figure out what exactly they were when they un-wind them in order to figure out the construction. I'd be pretty surprised if its not very near a 5K primary though.
Click to expand...
Thannks can you pls share link of chinese transformers you bought ? It would be appreciated
 
Musa Zahid said:
Thannks can you pls share link of chinese transformers you bought ? It would be appreciated
Click to expand...

Amazon.com: ziaoou 1PCS Tube Amplifier Single-Ended 5K Single-Ended Output Transformer for 6P1 6P14 6P6 0-4-8 Ohm DIY Vacuum Tube Amplifier, black, 512852 : Industrial & Scientific

Amazon.com: ziaoou 1PCS Tube Amplifier Single-Ended 5K Single-Ended Output Transformer for 6P1 6P14 6P6 0-4-8 Ohm DIY Vacuum Tube Amplifier, black, 512852 : Industrial & Scientific
www.amazon.com

you can get those from several vendors but they all appear to be the same thing. I bought them from whoever had them listed for the least amount of money on that specific day. Usually not the ideal criteria for shopping hifi components but I was curious what the absolute cheapest thing I could find would do.

If you want a lot of words, here is my end result

Making the Magnavox AMP-197 sing

I've made mention in a few other unrelated threads that I've been fooling with a single ended Magnavox amp, and promised I'd do a writeup once I was done. Well I am and this is that. First to set the stage, this amp came from here...
audiokarma.org

but 4.2 watts, flat within 0.5db from 30hz - 20khz and power bandwidth (half power) down to 23 hz. Better iron might get you flat down to 20hz but there isn't all that much happening between 20 and 30 and its going to need a fair bit more physical size to get there.

Can always throw one on and see how it compares to the original. Swap the second on and either leave it, or just make use of the amp while you have the failed original re-wound depending on those results.
 
Musa Zahid said:
Thank you everyoneits great to hear from all of you I will get the transformers checked today from an expert then will get the board fixed as per schemetics then will give it a try again i hope it works . Will get the transformer varnished again .
Click to expand...
It would also help us to help you if you can tell us where you are based.
 
You must log in or register to reply here.
Back
Top Bottom