USB audio DAC, bluetooth reciver and shielded relays for tube amplifier - Page 1
Forum section: electronics / beginners

author: WildMOSFET
author_rank: Contributor
timestamp: March 17, 2019, 07:26:45 pm
content: Guys, I'm designing a vacumm tube audio amplifier.Configuration: push-pull ultralinear class B of EL34But I need some opinions.In addition to the analog line entry, I would also like to put a couple of modules:1) DAC composed of USB input, analogue line output.2) Bluetooth audio receiver, always with line out.Can you recommend ready-made and tested modules?Can you also advise me on shielded relays for input selection? (old school method)Thanks for the attentionThis is the 3D model of amplifier:

author: jmelson
author_rank: Super Contributor
timestamp: March 17, 2019, 08:21:22 pm
content: Hmm, monolithic ICs, vacuum tubes and RELAYS? Gee, think you can fit a Diesel engine in there, too? Just to make sure you have all the major technologies covered in one project.Jon

author: WildMOSFET
author_rank: Contributor
timestamp: March 17, 2019, 08:35:48 pm
content: I think I have all the skills needed to bring these different technologies together.I just need to find these two modules.Ah, I see the diesel engine well anyway.Probably the beginner section is not very suitable for this thread...

author: Audioguru
author_rank: Super Contributor
timestamp: March 17, 2019, 10:28:58 pm
content: Why are you designing an antique vacuum tubes amplifier that is 60 years old?Where will you find the vacuum tubes and output transformers today?

author: floobydust
author_rank: Super Contributor
timestamp: March 17, 2019, 10:33:22 pm
content: You are better off asking your questions at thediyaudio.com forums.There is support there for whatever technology or circuit you want to build and listen to.

author: Gyro
author_rank: Super Contributor
timestamp: March 17, 2019, 10:36:59 pm
content: @Audioguru:There are still plenty of audio transformer manufacturers (not sure about Canadian suppliers, but certainly US and Europe) and vacuum tubes are still readily available. As for the reason, builder's choice.@WildMOSFET:Looking at your images, the mains transformer and output transformer are not in the ideal orientation (windings all vertical) you are running some risk of induced hum.

author: WildMOSFET
author_rank: Contributor
timestamp: March 18, 2019, 11:03:32 am
content: Quote from: Gyro on March 17, 2019, 10:36:59 pmI agree, as far as the material is concerned, you can find everything, just search on ebay to get an idea.@Gyro, you're right, the power transformer must be placed horizontally and the cores must not be aligned. I missed this detail.I think I found everything:USB-DAC -> Line output:https://it.aliexpress.com/item/Lusya-XMOS-U8-AK4490-Modulo-NE5532-DAC-USB-Decoder-Scheda-Audio-Supporto-per-16-32bit-192/32880205812.html?spm=a2g0y.search0104.3.63.60e1497fC73gt8&ws_ab_test=searchweb0_0%2Csearchweb201602_7_10065_10068_10890_319_10546_317_10548_10696_10084_453_454_10083_10618_10304_10307_10820_537_536_10902_10843_10059_10884_10887_321_322_10103%2Csearchweb201603_51%2CppcSwitch_0&algo_pvid=d72ff831-4e2d-40db-b39c-97785c5e06da&algo_expid=d72ff831-4e2d-40db-b39c-97785c5e06da-9Bluetooth receiver -> Line output:https://it.aliexpress.com/item/Lusya-CSR8675-Bluetooth-5-0-Senza-Fili-a-Bordo-del-Ricevitore-PCM5102A-I2S-DAC-scheda-di/32889060488.html?spm=a2g0y.10010108.1000023.14.299013e3edP6bo

author: Gyro
author_rank: Super Contributor
timestamp: March 18, 2019, 06:49:56 pm
content: Quote from: WildMOSFET on March 18, 2019, 11:03:32 amThe PCM5102A sounds very nice in the Arcam miniBlink. Of course implementation is everything, with much more impact than the devices used.

author: DimitriP
author_rank: Super Contributor
timestamp: March 18, 2019, 07:06:47 pm
content: Quote from: Audioguru on March 17, 2019, 10:28:58 pmTransformers are easy. He can order from "next door"http://www.antoniadis.com/if he can't find anyting locally.

author: WildMOSFET
author_rank: Contributor
timestamp: March 19, 2019, 10:20:42 am
content: Quote from: Gyro on March 18, 2019, 06:49:56 pmI was looking at the datasheet of the components and they seem to have good features.@Gyro: Thanks for the feedback on PCM5102A. I agree on the implementation.Instead regarding the relays for the selection of the inputs, I think they go well with the simple miniaturized relays.If the contact area is small and the positioning is correct, they should not absorb many electrical disturbances.If it works badly I can add a shield around (obviously connected to the ground).If anyone is interested, I put the datsheets below.USB-DAC:https://www.akm.com/akm/en/file/datasheet/AK4490EQ.pdfhttp://www.ti.com/lit/ds/symlink/ne5532.pdfBluetooth reciver:https://www.qualcomm.com/media/documents/files/csr8675-product-brief.pdfhttp://www.ti.com/lit/ds/symlink/pcm5102a.pdf