DIY audio: what are you building?

[Red MacKay]

Well, that is bloody sad!  At the time when I made my enquiry, I thought it strange that I did not hear back from him, but just felt I was getting the run around similar to the gentleman in Perth who was trying to sell me what he wanted and not what I was requesting.  In the end - I just couldn't be bothered with it.

 

I sincerely hope Peter is on the mend, well comfortable as possible.  And thanks, it's appreciated for letting us know Peter's situation.

 

Great to know we can still source Australian made Harbucks quality into the future too.

 

[andyr]

8 hours ago, peter mcc said:

 

Hi there. A brief update on Harbuch - Peter T (the owner) was admitted to hospital at the start of May and isn't able to return to work. He wasn't well for a few months before that. Both reasons go some way to explaining why you didn't hear back from him. For that I apologise.

 

 

No need to apologise, Peter #2.  That is very sad for Peter #1 - I hope he is able to make a full recovery.  (I had a triple bypass last November and would say I am completely back to normal - except I take a few more pills than did before!   )

 

Quote

 

I'm another Peter who was one of his bigger customers - last week took over Harbuch, fully intending to continue making great transformers locally. The domain/email has transferred across and I'm gradually getting the documentation. 

 

From what I've seen there is really good manufacturing documentation for the existing designs and I have the help of both current and previous staff to get things going again. There's lots to learn and understand but if I don't know the answer to a question I'm happy to admit it then get help to find it out - it's not my style to guess or make up answers.

 

Hopefully it's ok to post this as it is. I wanted to clear up why Harbuch seemed to drop off the face of the earth earlier this year. Mods - if I need to change something please let me know.

 

 

I wish you all the best in your venture.    As Red said ... great to know we can still source Australian made Harbuchs quality into the future.

 

Andy

 

Edited October 11, 2020 by andyr

[peter mcc]

4 hours ago, andyr said:

No need to apologise, Peter #2.  That is very sad for Peter #1

Bizarrely I'm actually Peter #3 - Harbuch was founded by Peter B, taken over by Peter T in 2007 and passed on to me in 2020! I anticipate a lot of awkward conversations in my future as I explain that yes, I am Peter but I'm not the Peter you think I am.

Edited October 12, 2020 by peter mcc
fixed date

[mwhouston]

If you have seen any of my posts lately you will see I’m listen to mono setups, mono simple tube amps and single horn and woofer. It is quite confronting and very immediate staring into a Altec horn from five meters away. Having a real and centre image not a virtual image as with stereo certainly is very different and hard to explain unless you have experienced it. It is raw and in your face. 

 

I form a mono signal from a stereo input with resistive network and from there it is amplified by the mono amp. I wondered  what if I used a stereo tube amp and joined their speaker posts in series with a jumper (- of one channel to + of the other) and spanned  the speaker (mono) from the posts. The OPT secondary windings would then be in series. It worked and under channel tests proved it works. It sounds like good mono and I get twice the power (4W in this case). The amp used here is one of my 6L6 SE UL wine box amp. The OPT secondaries float, neither side grounded. No NFB. 
 

Unless you are absolutely sure you can do this it could totally destroy your amp, tube or SS. I wouldn’t try it unless you are sure. Definitely not with an SS amp.  But if you are sure your tube amp floats its secondaries to the binding posts you could try this. For best effect position one speaker in the middle of the room facing directly to you. Try anything with clear uncompressed vocals for a real hifi experience.  Female jazz singers is always a good test of clarity in vocals.
 

 

 

 

[aussievintage]

7 minutes ago, mwhouston said:

The OPT secondary windings would then be in series. It worked and under channel tests proved it works. It sounds like good mono and I get twice the power (4W in this case).

 

Maybe not twice the power?  Each secondary is seeing a higher impedance and reflecting that back to it's primaries, which will affect the loadline  at the valve's operating point.  If the loadline was optimised for power before, it won't be anymore after doing this.

Edited October 12, 2020 by aussievintage

[mwhouston]

7 minutes ago, aussievintage said:

 

Maybe not twice the power?  Each secondary is seeing a higher impedance and reflecting that back to it's primaries, which will affect the loadline  at the valve's operating point.  If the loadline was optimised for power before, it won't be anymore after doing this.

Without CROing it does sound beefier. 

[aussievintage]

9 minutes ago, mwhouston said:

Without CROing it does sound beefier. 

Sure, it will have more power.  Whether it is exactly twice is doubtful though.  Did you optimise the loadline for power in the original design?  Often we don't,  and just use a transformer closest to the recomended.    If not, who knows whether the change brought you closer to the best, or further away. 

 

 

[mwhouston]

17 minutes ago, aussievintage said:

Sure, it will have more power.  Whether it is exactly twice is doubtful though.  Did you optimise the loadline for power in the original design?  Often we don't,  and just use a transformer closest to the recomended.    If not, who knows whether the change brought you closer to the best, or further away. 

 

 

The amp was designed around the 5K OPTs I had on hand.  

[Ihearmusic]

2 hours ago, mwhouston said:

If you have seen any of my posts lately you will see I’m listen to mono setups, mono simple tube amps and single horn and woofer. It is quite confronting and very immediate staring into a Altec horn from five meters away. Having a real and centre image not a virtual image as with stereo certainly is very different and hard to explain unless you have experienced it. It is raw and in your face. 

 

I form a mono signal from a stereo input with resistive network and from there it is amplified by the mono amp. I wondered  what if I used a stereo tube amp and joined their speaker posts in series with a jumper (- of one channel to + of the other) and spanned  the speaker (mono) from the posts. The OPT secondary windings would then be in series. It worked and under channel tests proved it works. It sounds like good mono and I get twice the power (4W in this case). The amp used here is one of my 6L6 SE UL wine box amp. The OPT secondaries float, neither side grounded. No NFB. 
 

Unless you are absolutely sure you can do this it could totally destroy your amp, tube or SS. I wouldn’t try it unless you are sure. Definitely not with an SS amp.  But if you are sure your tube amp floats its secondaries to the binding posts you could try this. For best effect position one speaker in the middle of the room facing directly to you. Try anything with clear uncompressed vocals for a real hifi experience.  Female jazz singers is always a good test of clarity in vocals.
 

 

 

 

 

Paralleling two opt secondary is halving the impedance and does god knows what to the reflected impedance on the primary.

The operating point of the tube is likely of the chart and the distortion gone through the window which explains the beefier sound you are hearing.

Floating the secondary of an OPT is never a good idea.

If you have a short in the OPT you could kill someone!

So, a bad idea all together.

There is also a reason why we enjoy listening to a stereo set up and not a mono set up.......

[mwhouston]

2 minutes ago, Ihearmusic said:

Paralleling two opt secondary is halving the impedance and does god knows what to the reflected impedance on the primary.

The operating point of the tube is likely of the chart and the distortion gone through the window which explains the beefier sound you are hearing.

Floating the secondary of an OPT is never a good idea.

If you have a short in the OPT you could kill someone!

So, a bad idea all together.

There is also a reason why we enjoy listening to a stereo set up and not a mono set up.......

The secondaries, as I said above, are in series. 

[mwhouston]

3 hours ago, Ihearmusic said:

Paralleling two opt secondary is halving the impedance and does god knows what to the reflected impedance on the primary.

The operating point of the tube is likely of the chart and the distortion gone through the window which explains the beefier sound you are hearing.

Floating the secondary of an OPT is never a good idea.

If you have a short in the OPT you could kill someone!

So, a bad idea all together.

There is also a reason why we enjoy listening to a stereo set up and not a mono set up.......

After listening to this setup for the last four hours I hope all my ideas are this bad. In for another four hours tomorrow. Can’t wait. Bring on BAD. 

[Guest]

Knocked up a couple of OB based on an older Japanese design just to try things out. All salvaged material from packing crates- I just hate to see this stuff thrown out without at least trying to reuse it!

 

A bit rough n ready (cut with a battery circular saw and jigsaw) but fit for purpose and working quite well. Expectations were of a very squashed soundstage but the height is actually quite reasonable.

 

 

[betocool]

That looks really interesting. There was an open baffle design I was very keen to try way back in the day, but never got around to it.

Looked like this...

 

 

Cheers,

 

Alberto

[aussievintage]

17 minutes ago, betocool said:

That looks really interesting. There was an open baffle design I was very keen to try way back in the day, but never got around to it.

Looked like this...

 

 

Cheers,

 

Alberto

 

Looks cool, but I thought open-baffle theory said you had to have a substantial distance from the driver to the edge of the baffle?

[betocool]

I wouldn't know exactly, but it was put off by the fact that you needed a good metre away from the walls for them to really shine through. That was off-putting because of lack of space in my case.

 

Still, I would not mind building a pair like that.

 

Cheers,

 

Alberto

[Reihana]

Just finished this off.

 

Didn't have a phono pre on the new stereo so decided to build one... 6 months later here we are!

 

Built on Merlin's 3-valve phono pcb.

Dead quiet, in spite of the proximity of the output to the PT, must have gotten a good one from Edcor this time.

 

Picked up an old Beacon universal output transformer which will be going into a Williamson type mono-block.

Hopefully I can find a second one to build in stereo but I'm not getting my hopes up.

[aussievintage]

1 hour ago, Reihana said:

Merlin's 3-valve phono pcb

Just looked that one up.  Split passive RIAA.  Virtually the same topology that I build using point to point wiring.  It's my phono of choice.  I think it offers one of the best sounds of any phono I have tried.

 

Well done, looks neat.  What valves are you using?

[mwhouston]

1 hour ago, Reihana said:

Just finished this off.

 

Didn't have a phono pre on the new stereo so decided to build one... 6 months later here we are!

 

Built on Merlin's 3-valve phono pcb.

Dead quiet, in spite of the proximity of the output to the PT, must have gotten a good one from Edcor this time.

 

Picked up an old Beacon universal output transformer which will be going into a Williamson type mono-block.

Hopefully I can find a second one to build in stereo but I'm not getting my hopes up.

Hey, looks a good build. For me (though it’s not about me) I like a painted top plate and any open frame trannies go under the bonnet. Love the wood cheeks. I’ve used and are still using Edcor trannies, top value for money. But if in a hurry use Hammond power trannies from Evatco in QLD. 

[Reihana]

25 minutes ago, aussievintage said:

Just looked that one up.  Split passive RIAA.  Virtually the same topology that I build using point to point wiring.  It's my phono of choice.  I think it offers one of the best sounds of any phono I have tried.

 

Well done, looks neat.  What valves are you using?

Got a pair of ECC81s in the gain stages and an ECC82 for the cathode follower. 81s are a pair of old Telefunkens, one of them was microphonic but works fine for the second gain stage. 82 is a military Sylvania, managed to get a pair of them for cheap and seems to behave well.

 

Would love to see your build! What valves are you using?

[Reihana]

8 minutes ago, mwhouston said:

Hey, looks a good build. For me (though it’s not about me) I like a painted top plate and any open frame trannies go under the bonnet. Love the wood cheeks. I’ve used and are still using Edcor trannies, top value for money. But if in a hurry use Hammond power trannies from Evatco in QLD. 

Yeah I was hoping to get something closed for the choke but as you well know options can be limited in Oceania (NZ) without paying an arm and a leg! I had a pair of closed Hammond inductors but already have them assigned to an upgrade on a pair of Wave-8 monos, and another vintage Collier inductor that was a bit small to use here. I ran out of space to in the case to fit the inductor inside otherwise would have gone that way. Will swap it out down the line once I find something suitable.

 

Cheers

[mwhouston]

6 minutes ago, Reihana said:

Yeah I was hoping to get something closed for the choke but as you well know options can be limited in Oceania (NZ) without paying an arm and a leg! I had a pair of closed Hammond inductors but already have them assigned to an upgrade on a pair of Wave-8 monos, and another vintage Collier inductor that was a bit small to use here. I ran out of space to in the case to fit the inductor inside otherwise would have gone that way. Will swap it out down the line once I find something suitable.

 

Cheers

In preamp PSs and tube phono PSs I use Hammond 5H 50mA chokes from Evatco. Not pricey and quite small but open frame. They go inside a PS enclosure and not a appearance issue. Keep them in mind. Usually I order four at a time to save on postage. I go through more than four a year. 

[aussievintage]

8 minutes ago, Reihana said:

Got a pair of ECC81s in the gain stages and an ECC82 for the cathode follower. 81s are a pair of old Telefunkens, one of them was microphonic but works fine for the second gain stage. 82 is a military Sylvania, managed to get a pair of them for cheap and seems to behave well.

 

Would love to see your build! What valves are you using?

I use 12AX7s for the gain and 12AU7, or better, 12AD7, 12AZ7, 12AT7 etc for the final cathode follower driver (some of the options can offer lower output impedance than the 12AU7)

 

My favourite 12AX7s are Psvane.

 

None of my builds are as pretty as yours.  I am the sort that just wants function     You'll see I don't have a power transformer.  I use a 12 AC plugpack into a backwards 12 to 240 transformer for power.

 

This is the neatest.  You'll notice cans on the gain valves.  Depending on where you have the preamp, you may find your's will benefit from this as well.

 

 

This was the prototype.  Certainly rugged.  

 

 

Finally, the two gain stages of the phono are built in to the front end of this phono/line preamp.  This one Has a power transformer and valve rectification

 

[Reihana]

11 minutes ago, mwhouston said:

In preamp PSs and tube phono PSs I use Hammond 5H 50mA chokes from Evatco. Not pricey and quite small but open frame. They go inside a PS enclosure and not a appearance issue. Keep them in mind. Usually I order four at a time to save on postage. I go through more than four a year. 

Good price and footprint on that choke. I'll definitely look at getting some. Thanks for the tip!

[Reihana]

12 minutes ago, aussievintage said:

I use 12AX7s for the gain and 12AU7, or better, 12AD7, 12AZ7, 12AT7 etc for the final cathode follower driver (some of the options can offer lower output impedance than the 12AU7)

 

My favourite 12AX7s are Psvane.

 

None of my builds are as pretty as yours.  I am the sort that just wants function     You'll see I don't have a power transformer.  I use a 12 AC plugpack into a backwards 12 to 240 transformer for power.

 

This is the neatest.  You'll notice cans on the gain valves.  Depending on where you have the preamp, you may find your's will benefit from this as well.

 

 

This was the prototype.  Certainly rugged.  

 

 

Finally, the two gain stages of the phono are built in to the front end of this phono/line preamp.  This one Has a power transformer and valve rectification

 

Great industrial vibes, I love it. Good way to re-purpose old equipment as well.

 

I thought about going with 12AX7's in the gain stages but wanted to try out something new, even though I've keep plenty of them lying around to use!

Might tweak the circuit later for them and see how it sounds. Will have a look at getting some shielding can's too!

 

Cool idea with the reverse 12v transformer. What's the current requirement for the power pack?

 

Cheers

[mwhouston]

17 minutes ago, Reihana said:

Good price and footprint on that choke. I'll definitely look at getting some. Thanks for the tip!

Because the preamp draws way less than 50mA the choke looks and acts a lot bigger. In a double Pi filtration with about 400uf of caps you will achieve a dead quiet PS.As you can see I DC my filament voltage. Only because I share the earth with both the HT and filament. 

Edited October 12, 2020 by mwhouston