How to build a Cool tube guitar Amp using a Old Lafayette Police Radio

D-lab does it again! This time we modify/retrofit an old 70's vintage HA-520 Police VHF receiver into a Class AB 6AQ5 amplifier. A great inexpensive solution to creating small rugged practice amps with an Industrial look! Note: The bias info only applies to cathode resistor type biasing NOT for bias using negative voltage. Hope you enjoy this fine Tube amp Theater presentation!

[@ringostarr4520]

I'll tell you why Terry shares this knowledge for free... cuz he's a good guy! It is about passing on the torch to the next generation and that is why we keep supporting the channel by watching. Thanks Terry your good karma score continues to rise with each video you post.

[@johnmccabe7645]

the stuff you post for free is like the grateful dead allowing fans to tape all the shows: it increased their reputation by removing profit motive. thank you sincerely

[@d-labelectronics]

Thanks man, I want the old tube stuff to live on!

[@crazyuncleduke8012]

I'm all for re-purposing everything that can be re-purposed. Great vid Terry Thanks.

[@Super8Rescue]

back in 1968, as a kid, I would pull radios apart just like this, it's a great pity I never learned how to re engineer things back together! Cheers to you too, excellent video.

[@cuban9splat]

You do this for all the right reasons. The main one is you LIKE doing it. Working on old tube circuits is fun. Keep the great videos coming.

[@davypeleman3672]

Thanks man for charing and teaching. I now can make my own amps. Already made one now and it works the way it should. So thanks again for teaching me that. Will try to share that knowledge also. So tube amps will never be extinct.

[@GhostWorkersComp]

Love it and great to actually hear from Marcia!!! Keep it up and keep posting.

[@jamesdrew8569]

Elegance, demonstrated. I like to see vids like this!

[@garyalberts4217]

I really appreciate the tips on why you see different voltages depending on the type of phase splitting used in an amp. Thank you!

[@DeadKoby]

I appreciate your sharing of the technology. these type schematics are out there, but I wouldn't have thought of snagging parts from an old police radio. This re-purposing/upcycling is never a bad thing.

[@scottirving4265]

Can’t say enough about these videos. Really well done, thank you.

[@matieupizil424]

Thanks for the schematics Terry, much appreciated. I’ve referenced them many times but have yet to copy one. There’s nothing like a genuine D-Lab amp built by the founder I’m sure. The schematics you post are more like an educational tool to a lot of us. Please keep fighting the good fight, your info is so clear and safety oriented

[@ChrisJohnson-pm9jf]

Love the "hand acting" in the recent D-Lab vids. Reminds of the old Mr. Bill stuff, especially when Terry crushes the IR cans. Amazing vids, and so worthy!

[@d-labelectronics]

I loved Mr Bill + The Gong show!

[@Finom1]

Bless you for sharing your wisdom with us!!! Thank you for teaching us!!!

[@sam127001]

in my opinion, you just gave an old piece of gear a 2nd chance at life. Nice video !

[@d-labelectronics]

Yes Sir, I found it at a swapmeet, I'm sure it was headed for the radio graveyard, if it did not sell

[@sdfjgksgf]

Not only did you share what you did, you are selling the amp for a really incredible price.

[@audiotechlabs4650]

My response, Great! You hit another out of the park! What's she sound like? Thankz

[@tashpaug]

Terry, great video! Keep them coming.

[@d-labelectronics]

Will do, my friend

[@daveogarf]

COOL! "Robo-Cop", starring Dr./Prof. Peter Weller! "Your move, creep!" LOL! (Three cheers for 'rectumfiers'...)

[@johngerson7335]

Awesome video Terry, good stuff! Hope we get to hear that little guy sometime. I did kind of wish that you'd left the original control knobs in place, but hey, it's your work so Cheers!

[@83roadstar]

Great Video,very cool amp! a small amp that doesn't take up a bunch of real estate!

[@rciancia]

Terry, thank you for sharing this one. This is exactly what I have been looking for as you know. This is a great little design and I will surely be borrowing this one. The truth is its not authentic if its not a DLAB Amp. :) Many thanks and let me know if you ever need anything.... I have a 3D printer and can make quality PCB boards... just say the word... appreciate you sharing and its the least I can do in return. - Thanks Ron

[@d-labelectronics]

This cool Police radio amp is now listed on Reverb.com for sale

[@howardrose8481]

I may have missed this along the way, but have you ever published a collection of your work in schematic form? If not, please consider the possibility. I’d happily acquire a copy. Thanks.

[@rciancia]

Terry, on my projects I get alot of comments about how I connect my power cord to the switch and fuse. I have been educated and taught that the Black Wire (HOT) should go directly from the power cord to the fuse, and from the fuse to the power switch and power switch to the black(hot) from the transformer. The neutral (white) from the cord should be tired directly to the neutral from the transformer. I notice on this build you have the neutral going from the cord to the fuse. And of course Green ground to the chassis. Is there a general rule on the right way to do this that you can share in a future video ? This would go a long way to towards helping folks like me get this right. Many thanks my friend.

[@mikesamra9126]

Another fine video my friend.

[@elihansen820]

I love all of this stuff, but it’s so far over my head at this point, it seems like literal magic! Where would you suggest someone start looking for information if they wanted to get into building guitar pedals and amps?

[@TheAgentAssassin]

A true amp master .

[@skycarl]

Great video,,, thanks Terry.

[@jonnybeck6723]

Another great vid, Master Terry... Outside of the smaller pinout and size (and the convenience) are there any other reasons/characteristics that differentiate the 6AQ5 from the 6BQ5? er like (in your opinion) would a 4 x 6AQ5 make a decent 20/30 watt output stage? Maybe, being smaller their ability to dissipate heat might cause a problem ? Thanx in advance... and cheers

[@GL64]

Awesome! Well done!

[@tronics666]

Thanks! Your videos are always interesting. Love the vintage look. I wonder if Allied and Lafayette still exits?

[@w7hrcgreg]

Hi Terry; love all your work. Only on UR Skiz-mattic plate of the inverter tube, is not hooked up to the .033cap that goes to the output tube. Still great work. Greg

[@drewster583]

I have always wanted to convert a realistic navaho 431 into a solid state amp with the signal meter displaying the guitar signal. It would be a cool garage amp.

[@The0nionKnight]

This is so cool!

[@victorborg2174]

Nice project Terry - I am dying to find out how does it sound?

[@littlejohnny1498]

I wish one amp builder would do a series on wiring input, outputs, volume and tone pots. Beginners have more trouble with these things than anything else. Maybe someday someone will.

[@dazzlenconfused]

i second that that would be awesome if you covered the output section BTW great video

[@HarpinJScott]

Hey Terry, love the videos! On your grid cap tip, I'm guessing this would work for a AA1164 Princeton Reverb? Would I need to lift the end of the cap going to the tubes to measure leakage? Just wondering because, as you know, the PR is grid biased. Thanks!

[@wadehicks9270]

Nice build 👍👍👍👍👍

[@superhet7281]

Excellent! Creative! Outside the box thinking. Great job, Terry! I’m a proud “Lafayette Man” and I don’t mind the repurposing at all. But please don’t do that to a Starflite transmitter!

[@d-labelectronics]

Thank you my friend for you kind support of my crazy projects.

[@superhet7281]

You should replace that slide-rule dial with a nice D-lab logo! ;-)

[@wiccandog]

Thanks for sharing dlab. I love watching you have so much fun.

[@johnsoncustomcalls]

Kind of a similar gig, what all is usable in a Philco 50-1423? I found one in a local shop but they want $30 for it. If it has a lot of useful parts I might pick it up and try to convert it to a guitar amp.

[@electrolytics]

Straight up D-Lab!

[@dwightbehm4747]

Pretty cool terry Fastinating progects

[@blakejohnson7148]

Wow...Cool project!...I noticed you didn't put a speaker back into it...is there any speaker that size that would actually be suitable for such an amp? Is the amp designed to plug into a separate speaker cabinet? If so what kind? Do you plan to make a video demonstrating how the amp sounds?

[@d-labelectronics]

Hello, no speaker that size that I know of that could handle the wattage. The amp can accommodate a 4 or 8 ohm speaker. I do plan to shoot a live demo of the amp very soon. TD

[@blakejohnson7148]

Cool....look forward to hearing the amp...Thanks for the response!

[@jyhgtrsd8189]

Hi I was wondering I have a lafayette 250 stereo tube amp and it works just fine, its a hifi home amp but would i have to do to make one of the inputs L,R to work for guitar, it has 6 inputs and i tried them all theres one that works ok but i think it could sound better and have more punch with the vol, its 3 12AX7's 2 , 7188 and 4, EL86's 2 EL86's a side L,R so i guess what my question is, what the differents between inputs for home hifi and input for guitar? and what would i have to change on one of the inputs to make it more guitar friendly, and the spk out 4,8,16 ohms

[@mikesamra9126]

I use a lot of Russian K40y-9 paper in oil caps. They sound like a Jensen paper in oil but cost more like a 716P when you buy them from Eastern Europe.

[@paulveldhuizen8049]

Hi Terry, I found an old Lafayette HA-520 and would love to build your push/pull circuit. Is there a location or a way I can download or a jpeg of your schematic? Thank you Paul

[@johnwrench4speed]

I really appreciate your videos. If you have a chance, could you look into the Vox AC10 SRT head amplifier and what makes it so special. It is a 10 watt guitar amplifier. There is a KZbin Channel entitled "The Doug and Pat Show" they do a demo and they swear by this amp (I think it was limited to production between 1964 and 1966). Maybe this could be a project to replicate. Thanks.

[@garyalberts4217]

Great idea! I second the motion.

[@warpedgamingus]

Can you make a video on the red light for the hot rod deluxe I cant get mine out its lose and flickers maybe how to replace the whole thing

[@stevelueb7787]

Very Very COOL

[@RobertKohut]

Nice job!!

[@d-labelectronics]

What? No Robo puns?

[@RobertKohut]

I know, I wanted to make a pun but just couldn't come up with one this morning. Sorry! Perhaps next vid...LOL

[@charlesbickenheuser8281]

Very nice build. But shouldn't the fuse go on the HOT side of the power line ?? (Black)

[@d-labelectronics]

It's AC, same current flows both ways.

[@mikecanton5129]

wow very nice- have on my bench right now is the lafayette model-he-80 that wanting very,very badly begging me please can i be a radical guitar amp? and i said you bet you can!!!

[@tonyduncan9852]

Someone has to be first, I suppose. :) Great-looking conversion.

[@tymekrozanski123]

Ive got a trio tube receiver and power trafo and caps are exactly same or the caps were like that

[@stevec5000]

What are you going to do with all the dozens of tube guitar amps you must have by now?

[@d-labelectronics]

I sell them on Reverb.com

[@johnmccabe7645]

I also would like to hear it, full up so the distortion character can be judged

[@d-labelectronics]

Will get a live demo soon

[@dhpbear2]

The white sticker on the rear of the chassis reads '7-8-66'. You just trashed a 1966 vintage piece of gear! HOW COULD YOU? (just kidding :)_

[@d-labelectronics]

It was easy, better that the dump it was headed to

[@gordonbrace2173]

Over & out!

[@Mauitaoist]

There is one on Ebay right now for 35.00....I'm thinking want it

[@The0nionKnight]

Marcia! Let him post the schematics, cmon!

[@electrolytics]

I just got some "Tube" socks! They're warm. Just a little fuzzy! oooohhh....sorry.

[@d-labelectronics]

Are they Cinch sockets?

[@electrolytics]

Socks. Not sockets. I used to wear solid state socks. Now I have tube socks. Much warmer. Little fuzzy.They get a little stinkier though. In a good way.

[@d-labelectronics]

Oops, my bad man, always have tubes on the mind