Page 1 of 7

#1 PP3521 idht

Posted: Fri Mar 17, 2023 6:29 pm
by Paul Barker
Image Here next to a PX4
Image

Image

bbcode image
Image
2.3 watts into 2k opt
Imageshare picture
I only have two bases br7 pin I expect theyre called.

Possibly bought the valves from Colomore, Ill ask them about more bases… I don’t need valves.

#2 Re: PP3521 idht

Posted: Fri Mar 17, 2023 6:50 pm
by IslandPink
Another obscurity from your stash ?
Looks very good.

#3 Re: PP3521 idht

Posted: Fri Mar 17, 2023 6:53 pm
by Paul Barker
Mark was asking me in a pm which idht I planned using. I couldn’t remember it’s identifying name.
I could use a nother to drive it and the direct 4p1l in pentode mode as recommended by you Mark, ( just seen youre comment above ater starting this) as the input valve at Mark’s sweet operating point for 22 gain. Maybe heated with lead cell 2v battery, though those I bought for the valves when I bought them might not suffice so long after.

A pair of px4’s and there’s s a all dht project for Andrew’s boards, I just have 4 boards, and need to ask Andrew if there are two more available and availability of the 8 pin chip these days. Might be long in the future and after the initial idht here mentioned. A cooking amp for home TV and music.

Odd heater, might use a simple current source.

#4 Re: PP3521 idht

Posted: Fri Mar 17, 2023 7:11 pm
by steve s
I built a breadboard SET using those as output valves, they are not globe px4's but I would say they give the likes of the cosser 2p a run for their money.

For me you can tell the different sound of smaller anode in comparison.
Nevertheless they are very nice valves especially considering what they cost.
I'd also be using them as a driver when a higher signal voltage is required, I have them in the back of my mind if I ever build an amp for the 4300a or the da100 which are waiting in the wings.

#5 Re: PP3521 idht

Posted: Fri Mar 17, 2023 7:12 pm
by steve s
I have a few bases Paul

#6 Re: PP3521 idht

Posted: Fri Mar 17, 2023 9:13 pm
by Paul Barker
Oh great, I just need another two.

At this stage I’ll use the 3k Rcore opt’s, so output power lower but probably less distortion.

I’ll hope the celectian field coil guitar speakers are efficient enough Steve Cresswel thinks they could be. Otherwise the 108sigmas might be efficient enough. Those in OB partnered with 12” isophon bass units made a good sound at Owston on 6 x 3 plasterboard mashups. It could transfer to 3’ x 3’ Briggs dimensions plinths I have already in woodchip floor material, which sounded very. Nice with Greatz field coils on a 2 watt amp at the time.but the Graetz cones have split, so ever hopeful the celestions are a replacement. Rediculous that Ive not tried those yet. A head full of ideas, but a laxidaisical production rate these days. Maybe if I just go back to a lump of wood breadboard amps again it would suit my present situation. Would be nice to recapture something of my past.

Work ever harder though and less strength available. Lost my money tree think the conservatives have it.

About ten weeks ago I was called by resus, Diana was there, me and Sam stood with her has she was fitting and foaming at the mouth unconscious from when we arrived around 3.30 afternoon, and we went home leaving her in resus T midnight, just couldnt stand at her head overlooking her torture. All the more reason Im still working, or everything would come down like a house of cards. Diana survived that attack, but I know one day she’ll be gone, if Im not run over by a bus first. So these pressures slow down my actions or time. I have to do everything and provide everything. Diana doesnt get or ask for pip and she accepted their first ruling on blue badge. Its her disease, she can have her own free choice whether to fight those things or not . She choses not. But she certainly knows this disease is terminal. Her gp told her if she hadnt been in a a public place shed now be dead. I told her, “Roxy (our dog) cant ring 999 you know.” Its how I express my worst fears but geting it out in the open my feelings with and about Diana helps me. I kind of need that. I mean with Diana at home. We communicate about it I sort of need her help in it. Im not seeking support for it here, just explaining my lack of attemtion to valve projects. Enjoying the 801a amp anyway. Rome wasnt built in a Day.

#7 Re: PP3521 idht

Posted: Fri Mar 17, 2023 10:03 pm
by IslandPink
You know I won't expect you to do anything for any deadline, Paul.
I know this was going to be tough , and you're way better than I would be at coping with it.
Send my love to Diana.

#8 Re: PP3521 idht

Posted: Fri Mar 17, 2023 10:21 pm
by Cressy Snr
+1

#9 Re: PP3521 idht

Posted: Fri Mar 17, 2023 10:22 pm
by Paul Barker
Thanks. She has her mind back, a bit foggy slow of speach and forgetful. But shes supported and still works from home trying to get people into worrk for now as her leader is very supportive. Contract comes to an end but shes exploring for follow on work. She knows very well what will probably come but less stressed out by it than me. I found out Im ans Aspie, for a wife to stay with an Aspie she has to be a very special person. Diana certainly is that and mostly Ive not been worthy of her, but all is well now in our rrelationship. She’ll never get me as Im unfathomly different to neurotypical people but shes my helper through the evils that come upon Aspiesin a world of people that are different. I am better at navigating people and might yet learn to coap in an alien world.
My higher skills at fixing boilers gives me happiness all the day. Excellence in engineering skills are my happy place. I want to keep going after September when I get state pension only. I dont know how long for as the mind is willing but the fingers and thumbs will call ttime, some days I feel it will be a short retirement career. But I dont think using them inside boilers though painful isn no harm yet, but some days hurt. So do physio therapists hurt us. Pain isnt a worry to me its a time for some pain but it is easy to coap with atm. If Diana passes Ill have these ways and routines to keep me going, and ill still be able to support the kids as they shall ever need their Dad as part provider. Naomi is managing without help, Sam is kept by us, but hes doggedly developing his bjj gym and winning most contests he enters. Its a pleasure to support him, and Ive given him charge of home security. He could turn a burglar into a pretzel pretty damn quick.
smoothflow academy. The rich member of it gave Sam a job as manager. Now hes given Sam all the shares. Martials arts dont make you rich. But hes excellent in his practice and has a big ffollowing of competent gym members supporting him. Id want nothing more for either child. Better to spend youre life persuing excellence in what you love doing. My happiest job when 16 was “farm hand” 50 New pence an hour. But never been happier. Todays world is sh11t compared to 1973.

The Smoothflow members often see me in tha sauna and always show great respect. When Diana was so ill to the last member they were offering anything we needed. Sam is a lovely soul and we get on so well, I repect all hes achieved and am fully behind him, and he respects me.

#10 Re: PP3521 idht

Posted: Fri Mar 17, 2023 10:41 pm
by Paul Barker
I think this idht project will keep my spirits up.

#11 Re: PP3521 idht

Posted: Sat Mar 18, 2023 12:05 am
by steve s
Cressy Snr wrote: Fri Mar 17, 2023 10:21 pm+1
+2.

#12 Re: PP3521 idht

Posted: Sat Mar 18, 2023 1:38 pm
by Ali Tait
steve s wrote: Sat Mar 18, 2023 12:05 am
Cressy Snr wrote: Fri Mar 17, 2023 10:21 pm+1
+2.
+3.

#13 Re: PP3521 idht

Posted: Sat Mar 18, 2023 6:23 pm
by Max N
+4

#14 Re: PP3521 idht

Posted: Sun Mar 19, 2023 3:19 pm
by Paul Barker
Thanks all.

Ive found a paire of core transformers’ I wound multilayered for 6080 2k:8ohm. Perfect.

Also note my valves were in bbc stock 1948.

Ive put the valve on the opt for a perspective. More than 2watt capable.

Image

Image

Image

#15 Re: PP3521 idht

Posted: Sat Apr 01, 2023 2:07 pm
by Paul Barker
Planning a build I was all set to use 1931 mesh plate 27’s (it’s low input capacitance is good) so I thought idht’s all the way, I’d planned using two stages 27 linked by Hammond IT’s one each, ( dismattled and gap changed for lower current higher inductance, to suit 27’’) lower current operation than typical valves its designed for. 27 will benefit from more inductance as any compromise will be worsened by two stages the same.

But sadly I don’t know where I put my mesh 27’s…..

An easy fallback position is 6em7 first stage RCL with a hammond IT on power triode section. Certainly less risky for a build up of bass response losses, Would still sound great.

I want to stick to triodes. Input capacitance of stage one sketchy, so might change that to an RCL indirect pentode like ef86 if I can find any. Its also mesh plate.