Great pleasure this morning to receive the first batch of the gyrator PCB. After extensive testing we refined the layout and options for the PCB and now we have the final product ready for shipping! Unfortunately I will not be able to do some testing and shipping before end of February and I received a large number of requests already. I’m sure this batch will fly very quickly so please confirm your requests.
I will post soon the specifications and some circuit examples for this flexible gyrator board which can be used for DHT preamps (e.g. 4P1L, 01a, 26), amplifier drivers, A2 drivers, LTP drivers, parafeed output stages and more!
So check the For Sale section soon for more information.
Some days ago we discussed in DIYAudio using this board for a 2J27L preamp like this one:
The output FET follower is needed to for valves which have low current and high anode resistance which will struggle to drive large capacitances. The FET follower of your choice can be used instead.
A minimal circuit which sounds fantastic is the basic configuration of this PCB. With few changes this circuit can be used on many DHTs like 26, 4P1L, 10Y, 30, 30sp, 12, 71a, 45, 46, etc:
If you want to send me your requests please use ONLY the form below:
Boards tested and abused over the weekend. They work like a charm with 2SK170 FET. If SMD BF862 is used instead, an extra 15V zener is needed for protection between drain and source to protect them from any surge at power on (or power glitch).
The BF862 is an amazing fellow!
Boards are of superb quality: 2oz (70um) copper with ENIG finish on a 1.6mm FR4 laminate.
cheers
Ale
Hi Ale,
last time I heard you, before sending me the boards, you spoke about building instructions, BOM and circuit examples to be released.
At the time being this kind of info is still missing on your blog.
When do you expect to release them?
Hi Michele
Just ping me an email and will send you all the info
Thanks!
Ale
Hi Ale… Received 4 units gyrato PCB in March, came with BOM but no schematic!?
Why is R6 , 4.7M not on the list!? Why there’s two C1, 100nF and 220nF?
Planning to loaded my EL3N @ 14mA with it.
Thanks A Lot.
Best Regards from Singapore.
Desmond Kwan
Hi,
I will resend build guide with all the details and the answers to your questions above.
Thanks
Ale
Hi Ale.
Maybe you’re Argentinian. I don’t know, but I doubt it because I saw a post of yours with the Pumas jersey(and your name). But just in case, I’ll write in English.
I’m interested in adding your gyrator design to my 6C6-2A3 Radiotron amp. Do you have any recommendations? Or is it better to leave it for a separate preamp?
I’ll add to this question: which preamp would you choose for my amp? I’ve been looking for parts to make your 01a preamp, but it’s a difficult-to-find tube in Argentina. Perhaps there’s a substitute.
Thank you very much for your blog; I’m learning a lot.
Hi Guille
I’m indeed and I happen to be here in Argentina for the first time in 8 years visiting friends and family.
I reply in English because the blog is in English for international reach and access.
Hard to answer your question, it’s very open and with little context is hard for anyoune to make a recommendation. You may not need a preamp at all, if the driver stage in your 2A3 amp has enough gain adding more gain will be a problem. You may want to revisit the driving stage? Otherwise it will all depend on the valve you are able to get your hands on. So probably see what you can find and have a good search around my blog in which there are plenty of good examples. I’m very clear all the time about how a stage sounds to my ears and mostly I do mention which valves have not been succesful to me or am not convinced about them. So have a look around, it will clearly help making up your mind.
Good luck!
Ale
I was thinking of connecting the 6C6 as a triode. As far as I know, it improves the relationship with the 2A3. And if possible, adding your gyrator to the 6C6 to improve the performance of the whole thing. I’d like to play with the Coleman regulator, but I don’t think it’ll ship here.
Gracias Ale!