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Paul Spencer

DIY audio: what are you building?

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2 hours ago, Primare Knob said:

Finally started working on my first subs build, using Dayton RSS390HO drivers

The core plan was to keep them small, 410x410x410x18mm, with drivers and bracing that comes down to roughly 44l net.

The baffle is double 18mm, and I did manage to piece together the 3D bracing today.

Bought a router last weekend, as the blade of the jigsaw was warping too much and wasn't creating a perfect circle.

My plan is to finish the outside by using the same bamboo floor boards that are in the cinema room, but I will need the help of a table saw to get that right.

Hopefully my neighbour can be persuaded with some beers.IMG_20191022_123919825.jpegIMG_20191022_123909953.jpegIMG_20191022_194735547.jpegIMG_20191022_194720428.jpeg

Looks awesome. I was pricing up some routers myself today. Did you get one of those trim types or a big boy one?

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Looks awesome. I was pricing up some routers myself today. Did you get one of those trim types or a big boy one?
I bought the cheapest plunge router that Bunnings had to offer. I don't think the trim routers are suitable for this job.

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First glorious sound from my new headphone amp.  She's a hot one.  Nearly 40 watts of heat from those 2 power resistors alone. :)

 

6080/6AS7 based,   6SN7 driver.  Old Trimax chassis.

 

DSC_0433.jpg.e45de4864ac123fd473b510e7731c735.jpg

 

DSC_0430.jpg.bc68b64f24d27c6295ad19e19e38f6d9.jpg

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9 hours ago, Muon N' said:

Trimax iron too I expect :thumb:

Power and choke, yeah.  I don't know the current rating of the secondary on the power tranny, but I figure it was designed to handle a couple of EL34s at class A or near it, so a good couple of hundred ma I expect.  Seems to run quite cool.

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Spent some time listening to it today.  Really nice powerful sound and loud enough to damage hearing and then some.

 

However,  that Trimax transformer is actually putting out too much voltage, so I have had  to tweak operating points for the 6SN7 which determines the voltage the 6AS7 cathode follower runs at.   I also have to limit this because the Trimax choke must be only about 150ma.  It certainly gets a bit warm after an hour running at 150ma anyway, wouldn't like to push it harder.

 

So, despite the performance being impressive, this design sure is an energy waster. Everything runs hot, especially the load resistors and 6AS7s (picture of them nicely glowing below).   I also am a bit concerned about having over 150 to 200 volts sitting on the other side of the output coupling electrolytic capacitor.  That one component, that often fails, is all that's between the high voltage and my headphones.     I am glad I built it to this stage, but it may not be the headphone amp for me :) 

 

 

 

 

DSC_0436.jpg.91f3b417737d4331a71823086e64bbe5.jpg

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6 hours ago, aussievintage said:

 

Spent some time listening to it today.  Really nice powerful sound and loud enough to damage hearing and then some.

 

However,  that Trimax transformer is actually putting out too much voltage, so I have had  to tweak operating points for the 6SN7 which determines the voltage the 6AS7 cathode follower runs at.   I also have to limit this because the Trimax choke must be only about 150ma.  It certainly gets a bit warm after an hour running at 150ma anyway, wouldn't like to push it harder.

 

So, despite the performance being impressive, this design sure is an energy waster. Everything runs hot, especially the load resistors and 6AS7s (picture of them nicely glowing below).   I also am a bit concerned about having over 150 to 200 volts sitting on the other side of the output coupling electrolytic capacitor.  That one component, that often fails, is all that's between the high voltage and my headphones.     I am glad I built it to this stage, but it may not be the headphone amp for me :) 

 

 

 

 

DSC_0436.jpg.91f3b417737d4331a71823086e64bbe5.jpg

 

I built a headphone amp similar to yours some time ago using the 6AS7G as an output valve and the 6SL7GT as the input valve but opted for solid state rectifiers and pi filtering for all DC supplies in the end.

I attempted to use a valve power supply built on a recycled chassis at first but could not source a large enough choke and it was generating too much heat at the time.

Also a delay timer was implemented for the two HT supplies and an infrared motorized volume control on the input.

Output coupling capacitors were around the 100uF mark and bypassed with a 10uF Solen which I would like to upgrade some day. 

However it works extremely well on high impedance headphones such as the Sennheiser HD-650's and sounds magnificent without any hum.

I highly recommend this as a worthy OTL project.

 

Keep up the good work, it will pay off.

 

Still going strong after more than ten years.

100_0696.thumb.jpg.30b3059cf2f60794ecdab749a3ceddab.jpg

Below, the power supplies and amplifier module.

100_0682_00.thumb.jpg.5caf64588d20ce32fc92f00aad3f288e.jpg

 

 

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6 hours ago, MarcAL said:

 

I built a headphone amp similar to yours some time ago using the 6AS7G as an output valve and the 6SL7GT as the input valve but opted for solid state rectifiers and pi filtering for all DC supplies in the end.

I attempted to use a valve power supply built on a recycled chassis at first but could not source a large enough choke and it was generating too much heat at the time.

Also a delay timer was implemented for the two HT supplies and an infrared motorized volume control on the input.

Output coupling capacitors were around the 100uF mark and bypassed with a 10uF Solen which I would like to upgrade some day. 

However it works extremely well on high impedance headphones such as the Sennheiser HD-650's and sounds magnificent without any hum.

I highly recommend this as a worthy OTL project.

 

Keep up the good work, it will pay off.

 

Still going strong after more than ten years.

 

Below, the power supplies and amplifier module.

 

 

 

 

Thanks for the encouragement.   Yes, ditching the choke and improving the filtering is an option.  My supply voltage is already too high though. 

 

I think this will be a project I will keep coming back too and tinkering ...

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5 hours ago, aussievintage said:

 

Thanks for the encouragement.   Yes, ditching the choke and improving the filtering is an option.  My supply voltage is already too high though. 

 

I think this will be a project I will keep coming back too and tinkering ...

From memory I think that I used the transformer shown above the chassis for the B+ for the 6AS7G with a supply voltage of 122VDC @250mA with an extensive PI filtering network.

The other B+ was from a small reverse connected 6V - 240V potted transformer (mounted internally) for the 6SL7GT with a supply voltage of 250VDC @4.6mA with a simple PI filter.

The B+ rectifier diodes were all 1000V fast recovery types with snubber capacitors.

The heater rectifier diodes were Schotky types also with snubber capacitors.

There were separate heater power supplies used for each tube as the current for each was different and easier to control when separated.

The total outcome was very quiet and clean with no audible hum and less wasted heat.

It was a project that involved more power supply design than amplifier design in the end but well worth it.

Feel free to PM me for more details.

Regards, MarcAl.

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5 minutes ago, MarcAL said:

B+ for the 6AS7G with a supply voltage of 122VDC @250mA with an extensive PI filtering network.

Yes, I wish I had a low supply like that.  Mine sits at  about 350 VDC.  I have jiggered the operating point down to under 70ma, so the choke now only runs coffee cup warm, so should be OK long term.  That still puts the plate dissipation marginally high for one triode.  That's why I am using parallel 6AS7s, too share the load.  

 

However, it sounds too good to not be a keeper.    I just had a longer listening session and love it.    Despite now only pushing that lower output current, it still delivers ear damaging sound into headphones, even as low as my 50 ohm Sennheisers.

 

1671860335_DSC_04512.jpg.f564d6278b7069c066dacb315d2ee516.jpg

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4 hours ago, aussievintage said:

Yes, I wish I had a low supply like that.  Mine sits at  about 350 VDC.  I have jiggered the operating point down to under 70ma, so the choke now only runs coffee cup warm, so should be OK long term.  That still puts the plate dissipation marginally high for one triode.  That's why I am using parallel 6AS7s, too share the load.  

 

However, it sounds too good to not be a keeper.    I just had a longer listening session and love it.    Despite now only pushing that lower output current, it still delivers ear damaging sound into headphones, even as low as my 50 ohm Sennheisers.

 

1671860335_DSC_04512.jpg.f564d6278b7069c066dacb315d2ee516.jpg

I love it when function exceeds form by such a magnitude. There is something magic about listening to a project that looks “functional” but sounds exquisite.

 

The genie is out of the bottle 🙂

 

SS

Edited by Sub Sonic

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16 minutes ago, Sub Sonic said:

I love it when function exceeds form by such a magnitude. There is something magic about listening to a project that looks “functional” but sounds exquisite.

 

The genie is out of the bottle 🙂

 

SS

I find it an insult to DIY. Form and function must go together. I’m not saying it has happened here but those who say;  “I don’t care how it looks it’s how it sounds is important” are just offering a cop-out to the craft. 

 

I great deal of a of a lot of us put in huge effort to make our sonic creations look and sound good. Further the craft, it’s dying slowly. 

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22 minutes ago, mwhouston said:

I find it an insult to DIY. Form and function must go together. I’m not saying it has happened here but those who say;  “I don’t care how it looks it’s how it sounds is important” are just offering a cop-out to the craft. 

 

I great deal of a of a lot of us put in huge effort to make our sonic creations look and sound good. Further the craft, it’s dying slowly. 

Sorry, I cannot agree, most systems I have heard that are DIY and "look good" do not sound as good as other systems that are not so "good looking".
Each to his own but to say that someones hard work is an "insult" I think is taking things a bit too far.

 

If the "craft" is dying then perhaps you are the one doing something wrong?

 

@aussievintage go for it, I like your work and if it sounds good to you, well done.

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Give me a "wolfs in sheeps clothing" over a "show pony" any time, there is far too much "Audio W##K" if you ask me😀

cheers,

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1 hour ago, Sub Sonic said:

I love it when function exceeds form by such a magnitude. There is something magic about listening to a project that looks “functional” but sounds exquisite.

 

The genie is out of the bottle 🙂

 

A couple of my 'projects' have made it past the first build.  But many  just get used and enjoyed.  This one would require a complete strip down, sand a repaint, various boxes to hide the uglies, and it would still look, well, quaint? :) 

 

1 hour ago, mwhouston said:

I find it an insult to DIY. Form and function must go together. I’m not saying it has happened here but those who say;  “I don’t care how it looks it’s how it sounds is important” are just offering a cop-out to the craft. 

 

I great deal of a of a lot of us put in huge effort to make our sonic creations look and sound good. Further the craft, it’s dying slowly. 

Well, I think I should be insulted. 

 

Except, I think I separate, DIY for function, and aspirations to true craftmanship.  I know you sell some of yours, and they do look pretty.  This is never going to be my intention.

 

56 minutes ago, soundbyte said:

Sorry, I cannot agree, most systems I have heard that are DIY and "look good" do not sound as good as other systems that are not so "good looking".
Each to his own but to say that someones hard work is an "insult" I think is taking things a bit too far.

 

If the "craft" is dying then perhaps you are the one doing something wrong?

 

@aussievintage go for it, I like your work and if it sounds good to you, well done.

Yeah I didn't realise my little projects were so upsetting to people.

 

38 minutes ago, afa said:

Give me a "wolfs in sheeps clothing" over a "show pony" any time, there is far too much "Audio W##K" if you ask me😀

cheers,

Thanks mate.  I'd rather be doing this amateurish DIY than arguing over who has the biggest best specified class A, class D power amp :) 

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19 minutes ago, aussievintage said:

 

A couple of my 'projects' have made it past the first build.  But many  just get used and enjoyed.  This one would require a complete strip down, sand a repaint, various boxes to hide the uglies, and it would still look, well, quaint? :) 

 

Well, I think I should be insulted. 

 

Except, I think I separate, DIY for function, and aspirations to true craftmanship.  I know you sell some of yours, and they do look pretty.  This is never going to be my intention.

 

Yeah I didn't realise my little projects were so upsetting to people.

 

Thanks mate.  I'd rather be doing this amateurish DIY than arguing over who has the biggest best specified class A, class D power amp :) 

My comments are my personal views and of course not everybody else’s. I revel in the fact people still have a go to build gear that makes music, regardless  how it looks. I have read of lots of commercial gear which really was rubbish but looked the part. For me I will always ensure what I build sounds good (if only to some) and looks “finished”. But that is just me. I guess it doesn’t give me the right to say that other gear is an “insult” but I am voicing my opinion. For that, I’m sorry. 

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18 hours ago, mwhouston said:

My comments are my personal views and of course not everybody else’s. I revel in the fact people still have a go to build gear that makes music, regardless  how it looks. I have read of lots of commercial gear which really was rubbish but looked the part. For me I will always ensure what I build sounds good (if only to some) and looks “finished”. But that is just me. I guess it doesn’t give me the right to say that other gear is an “insult” but I am voicing my opinion. For that, I’m sorry. 

No probs.  I now know where you are coming from.  You do finish your stuff well.

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DIY audio: what are you building?

 

Well, to me that means post whatever DIY audio projects that you are building and share this knowledge and experiences with other like minded individuals whether it is built and finished or still in the building / designing phase.

 

At times it may look like Frankenstein has been here to some but that can be entertaining as well. Anyhow I like horror movies.

 

After all the journey can be just as satisfying than the end result. 

 

To all fellow DIY audio engineers, have a go and keep up the good work.

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6 hours ago, MarcAL said:

DIY audio: what are you building?

 

Well, to me that means post whatever DIY audio projects that you are building and share this knowledge and experiences with other like minded individuals whether it is built and finished or still in the building / designing phase.

 

At times it may look like Frankenstein has been here to some but that can be entertaining as well. Anyhow I like horror movies.

 

After all the journey can be just as satisfying than the end result. 

 

To all fellow DIY audio engineers, have a go and keep up the good work.

Yep have a go.

 

My local 80 year old mate Don struggles with a meter, can’t work ohms law and has no idea how to calculate watts. But he can read a schematic and builds the most  beautiful tube amps, tube preamps, and even tube MC preamps you will ever see and hear. 

Edited by mwhouston

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A3DF79A9-62CB-4832-A7BE-26526106DD4A.thumb.jpeg.a0e2b382f833a3bc52c6ac4b1383769a.jpeg
 

Can’t remember where I was up to in my last post but I thought I’d do an update. I’ve sealed the gaps from inside with silicone filler and added a reflex port as well as improving the wiring with better connectors and connections. Sealing and adding the port both made an noticeable difference and I’m now getting audible response down to around 40 Hz where before it was petering out around 50 Hz (not that I have any way to formally measure. I’m just running frequency sweeps with a voiceover)

 

I’m not sure about the port. I’m pretty sure winisd recommended a narrower one but my copy of parallels stoped working and this is what jaycar had in stock. Besides, I think it looks a little large, visually. For the final build, I’m planning to get my dad to turn some up out of aluminium so I can make it whatever size works best. 

 

I can feel the front and rear baffles vibrating a lot so the next thing is to try some bracing. Gotta say, though, I’m already pretty impressed with how it sounds. I’ve never spent any real time with full-range drivers so I wasn’t sure what to expect but I feel like these are going to end up sounding pretty good, which is reassuring considering how much work I’m planning to put into the final cabinets. The sound is still very unrefined but there’s potential there
 

I’ve decided to build the final cabinets out of mdf with a wood veneer finish because it will be much easier to get it to look good and seal properly than what I was planning with the ply, which would have been expensive and left absolutely no margin for error, which is not a great combination. I like the plywood edge so much though that I’m still going to have it there, it will just be a bit of trim stuck on. Yes, it’s a cheat. No, I don’t care. For me, the look is as important as the sound. 
 

I’m not sure what I’ll end up doing for legs. I’m weighing up a few options, none of which I love. I don’t have the skills or equipment to make something as nice as the originals. I’d be happy to hear suggestions if anyone has them. The idea is that they rake back around 8 degrees.

Edited by RankStranger

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27 minutes ago, RankStranger said:

I’m not sure about the port. I’m pretty sure winisd recommended a narrower one but my copy of parallels stoped working and this is what jaycar had in stock. Besides, I think it looks a little large, visually. For the final build, I’m planning to get my dad to turn some up out of aluminium so I can make it whatever size works best. 

The tuning of a port isn't just the diameter, but also the length.  It's been a long while since I built one, but there's lots of info around.

 

29 minutes ago, RankStranger said:

I can feel the front and rear baffles vibrating a lot so the next thing is to try some bracing.

Very worthwhile, yep.

 

29 minutes ago, RankStranger said:

I’ve never spent any real time with full-range drivers so I wasn’t sure what to expect but I feel like these are going to end up sounding pretty good,

I like listening to full range drivers.   Sure, they can't do all the bass and treble of multi-way, but they do sound nice.

 

31 minutes ago, RankStranger said:

I’ve decided to build the final cabinets out of mdf with a wood veneer finish because it will be much easier to get it to look good and seal properly than what I was planning with the ply

Noting the screws visible in the picture, I wonder if you have considered just gluing?   My TQWT speakers are MDF, all glued.  Glue seals everything well, is very strong.

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13 minutes ago, aussievintage said:

The tuning of a port isn't just the diameter, but also the length.  It's been a long while since I built one, but there's lots of info around.

Thanks. Yes, I meant that too. The look is more about the diameter though 

 

14 minutes ago, aussievintage said:

Noting the screws visible in the picture, I wonder if you have considered just gluing?   My TQWT speakers are MDF, all glued.  Glue seals everything well, is very strong.

I will use glue and screws on the final box and finish it much better. Any screws will be hidden under the veneer. These screws are the answer to "what’s the quickest, easiest structurally-sound way to get this together, considering I don’t care what it looks like?"

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Guest Muon N'

Managed to replace 2 or the stock regulators in my CD-60SE (MC7815ct and MC7915ct) with some of the Sparko Labs discrete ones I had in the old player, has made a very nice difference with greater transparency and more textured layering of instrument and vocals, strings and cymbals shimmer like they should, the thwack of a drum is as a thwack sound should sound more so now. Sound staging is nicer too.

Still have a positive 5v Sparko reg to fit once I work out how to attach it to the sink in place of the motorola original.

Removed the 220uf Cerafine caps that decoupled after them and replaced with 47uf Oscons on the underside of the PCB to have a little more room, and with the Sparko regs the cap doesn't need to be as large as previously.

 

256476500_Sparkox2.jpg.1115de091ca1d8b2914b9bb5f5f5f78b.jpg

 

 

 

 

 

 

Edited by Muon N'

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7 hours ago, RankStranger said:

 

I’m not sure what I’ll end up doing for legs. I’m weighing up a few options, none of which I love. I don’t have the skills or equipment to make something as nice as the originals. I’d be happy to hear suggestions if anyone has them. The idea is that they rake back around 8 degrees.

Bunnings have various leg options in steel and timber and may be able to be modified to suit your needs.

You could also make a plinth out of plywood perhaps.

Edited by MarcAL

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8 hours ago, MarcAL said:

Bunnings have various leg options in steel and timber and may be able to be modified to suit your needs.

You could also make a plinth out of plywood perhaps.

Thanks, Marc. The ones on it are from Bunnings. There are a few options there but nothing very elegant. I might experiment sound-wise with sitting it bolt upright on HiFiRacks-style legs a la the DVF O/96 but I’d like to have it rake back if i can. 

 

44541B50-8849-4D7F-AE61-949DE286757E.jpeg.c641e60e7b3fd9dd2f9346c71ded24cc.jpeg

 

The originals are very shapely and mid-century and I’d like to try to at least capture some of that

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