[BUILD] fripholm's TG1 Zener Limiter boards - support thread

[fripholm]

I just had the 550 and 559 on hand when I built my units so they ended up in the BOM. I don't see a reason why the others wouldn't work. On a closer look, they don't even match at their collector voltages (550 is 45 volts, 559 is -30).

Mine had the C classification (again, didn't give it much thought) but I don't remember any of those reading much more than 400 hfe on the meter (most were lower). Could have been the meter, though but I think if you grab at least B it'll be fine.

 

[andow]

I just had the 550 and 559 on hand when I built my units so they ended up in the BOM. I don't see a reason why the others wouldn't work. On a closer look, they don't even match at their collector voltages (550 is 45 volts, 559 is -30).

Mine had the C classification (again, didn't give it much thought) but I don't remember any of those reading much more than 400 hfe on the meter (most were lower). Could have been the meter, though but I think if you grab at least B it'll be fine.

Great, thanks for the info!

 

[Bernardo]

Hello, I have a problem with the meter. It doesn't move, it's the thin 1m meter of don audio VU dB Meter D1010SL Slim Audio, 30,08 € I have reviewed the negative and the positive and they are fine, the unit compress and limits well. I don't understand what is happening here. Thanks a lot.

 

[Bernardo]

sorry it was trim "88"

 

[SmokeyJoe]

Hey folks. Very excited to build this project and I've been pricing it up. Can anyone make some suggestions where I might be able to cut some costs? It's coming out ~£700 ($920, €830) for a stereo unit (without even a custom face plate or knobs) and ideally I want to keep the cost down a bit. Is this a reasonable price or has anyone done it for less? I'm in the UK.

£240 - Transformers (Sowter 4600 and 1462)

£120 - Meters and 4x 24 position rotary switches from DonAudio. I'm looking at these as the Elmas are eye-wateringly expensive Rotary Switch 2024, 2 Pole 24 Position, 10,21 €
Maybe I could use pots, but even then I expect I'll need expensive ones as they're in the signal path.

£130 - Components, sockets, switches etc from Mouser and Farnell (are WIMA films strictly necessary or can I cheap out? I'll use all Panasonic for electros)

£80 - 2U Enclosure (is there a recommended one?)

£17 - BC550Cs, as I can't find them anywhere cheaper. A previous post suggests these may be substituted - I have a load of BC547/557, not sure if they will work in place of 550s or 559s?

£75 - PCBs (fair enough and not really negotiable!)

And I estimate at least another £50 for connectors, wire, and a power transformer.

It all adds up fast!

Thanks in advance!

 

[dmp]

Transformers is the obvious place to cut some costs. Lots of 600:600 and 10k:10k line level options. Used is often fine.
Edcor XSM series are $25 each

are WIMA films strictly necessary or can I cheap out?

You can use whatever you want. The dependence on audio quality to individual components is a hard question, as it takes a lot of time to obtain the experience (ie changing components, listening to the results). The differences between caps in the signal path with the same capacitance is going to be subtle. Often I think people pay for something 'accepted' to be good, like WIMA, because the hours it would take to learn if there is a difference to the cheaper components isn't worth the difference in money. In my experience, there are many good brands of film caps, Mallory, Cornell etc... A no-name brand I would be reluctant to gamble on - more for durability and variation from the target value.

BC550Cs, as I can't find them anywhere cheaper. A previous post suggests these may be substituted - I have a load of BC547/557, not sure if they will work in place of 550s or 559s?

Did you look at the datasheet?

 

[Rob Flinn]

Look at the en55272 from CPC as an alternative enclosure. You should also look at places like rapid electronics & CPC for other parts. Mouser is quite good in the U.K if you meet the minimum free shipping with your order. However Farnell are expensive.

 

[SmokeyJoe]

Edcor XSM series are $25 each

Thanks, that's a great shout.

In my experience, there are many good brands of film caps, Mallory, Cornell etc... A no-name brand I would be reluctant to gamble on - more for durability and variation from the target value.

I typically use EPCOT or KEMET as they're reasonably priced and I've never had any issues. Not sure if they fall under 'no-name brand' but they're certainly towards the cheaper end of the scale - however, I'm happy to spend the extra on something like WIMA if it's genuinely worthwhile.

Did you look at the datasheet?

Not yet...I can compare the specs, but I don't have the knowledge to understand how much variance is acceptable for these transistors in this circuit, if the specs differ. Would you mind advising on which specs are important to match here please?

Thanks dmp, your advice is much appreciated.

 

[SmokeyJoe]

Look at the en55272 from CPC as an alternative enclosure. You should also look at places like rapid electronics & CPC for other parts. Mouser is quite good in the U.K if you meet the minimum free shipping with your order. However Farnell are expensive.

Thanks for the suggestions - I didn't spot that enclosure (maybe because I was searching for in stock items only). Looks like a great option.

Yes most of my bits are from Mouser, so easily hitting the minimum price there. I find CPC and Farnell often carry the same stock as I believe the companies are linked, so I'll use whichever works out cheaper (probably CPC in this case thanks to your enclosure suggestion).

Never used Rapid much before but I'll give them a look.

Cheers

 

[dmp]

Not yet...I can compare the specs, but I don't have the knowledge to understand how much variance is acceptable for these transistors in this circuit, if the specs differ. Would you mind advising on which specs are important to match here please?

Well take a look to see what specs are different between them. I pulled up the datasheet with a google search and the BC547 and BC550 are on the same datasheet - meaning they are very similar components.
A quick scan of the datasheet, it appears the different flavors differ in the absolute maximum ratings. Other than that the BC547 has a slightly higher noise figure than the bd550
Will the absolute max voltages matter? I don't know the circuit well enough to say. Will higher noise matter?

 

[freshfromtheden]

You don't need Elma switches, I bought mine from here CK1030 6 Position 2 Pole BBM Rotary Switch 150mA 250V and they're fine. (Don't remember if it was specifically that model I used for this build but there's a bunch of rotaries on there)

 

[freshfromtheden]

Buying expensive switches for something in the audio path is pretty meaningless, it's not going to affect the sound. The Elmas will last way longer, have a nicer action etc, but won't sound any different. I'm just some hobbyist in a shed with some synths, unless you're turning them hundreds of times a day, cheap switches are fine.

 

[dmp]

Buying expensive switches for something in the audio path is pretty meaningless, it's not going to affect the sound. The Elmas will last way longer, have a nicer action etc, but won't sound any different. I'm just some hobbyist in a shed with some synths, unless you're turning them hundreds of times a day, cheap switches are fine.

I see where you're coming from about it not affecting the audio path, but using super cheap switches in gear builds is something I've looked back on with regret. Your audio won't sound any different until the dumb switch fails. I've had to go back and replace bad switches which is super annoying.

 

[SmokeyJoe]

Well take a look to see what specs are different between them. I pulled up the datasheet with a google search and the BC547 and BC550 are on the same datasheet - meaning they are very similar components.

Hey thanks, that's really helpful. You're right though, I could have done that myself. I'll see what I can figure out on my own and come back if I have more questions.

You don't need Elma switches, I bought mine from here CK1030 6 Position 2 Pole BBM Rotary Switch 150mA 250V and they're fine. (Don't remember if it was specifically that model I used for this build but there's a bunch of rotaries on there)

Cheers, yeah I'm using Lorlins for most of the rotary switches, but it's recommended to use 24 pole rotaries if swapping for the input/output gain pots, which seem to be inherently expensive. I've considered using 12 pole instead, which would be much cheaper but lose some resolution or range.

I see where you're coming from about it not affecting the audio path, but using super cheap switches in gear builds is something I've looked back on with regret.

I totally agree with you here. Alas I'm on a budget for this build and can't be spending ~£40 a pop on rotary switches. I figure I can go with the cheaper ones for now and switch them out if they fail in a few years.

 

[innercityman]

Transformers is the obvious place to cut some costs. Lots of 600:600 and 10k:10k line level options. Used is often fine.
Edcor XSM series are $25 each

40€ at don-audio.com in Europe.

 

[SmokeyJoe]

40€ at don-audio.com in Europe.

Thanks, found them. Edcor XSM600/600 and XSM10K/10K, right?

Edit: After looking at shipping costs from Germany and taking into account the likelihood of being charged import duty, I think I'd be better off ordering the Sowters from the UK.

Would 4600 10K/10K and 4603 600/600 be a suitable choice?

 

[innercityman]

Thanks, found them. Edcor XSM600/600 and XSM10K/10K, right?

Edit: After looking at shipping costs from Germany and taking into account the likelihood of being charged import duty, I think I'd be better off ordering the Sowters from the UK.

Would 4600 10K/10K and 4603 600/600 be a suitable choice?

Yes, that's this series. Did you check UTM industry in Poland ? Igor from IGS audio has very large variety of transformers for every kind of design. He offers perfect copies of Carnhiill.

UTM Industry

 

[SmokeyJoe]

Yes, that's this series. Did you check UTM industry in Poland ? Igor from IGS audio has very large variety of transformers for every kind of design. He offers perfect copies of Carnhiill.

UTM Industry

Thanks, I'll give them a look. Ideally I'm hoping to find a UK supplier as it's a pain to order anything from Europe these days. Canford have a decent range but they're all pretty expensive. Guess I'll just have to suck it up.

 

[innercityman]

Thanks, I'll give them a look. Ideally I'm hoping to find a UK supplier as it's a pain to order anything from Europe these days. Canford have a decent range but they're all pretty expensive. Guess I'll just have to suck it up.

Yeah, but check the prices of these trx, you'll be surprised, and the quality seems to be really good. Check this thread UTM. I've ordered a pair of inputs and output transfomers for my dual REDD47, and they didn't take long to arrive, but I'm from France.

 

[warpie]

Why not ordering from AML since you're in UK? They have both Carnhill and Sowter I believe and you won't have to mess with import taxes, etc...