Hot Rod Deluxe | Headroom & the 12AY7 "Mod"

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[@pointyboot]

You know, these amps get a lot of crap, but as a sound engineer I'm always happy to see one on stage. They sound great with any guitar. True work horses.

[@GlennJimenez]

I remember being blown away by The Killers backline years ago. They had these nice Hiwatts...and next to them was a hot rod deluxe!

[@jonoftheford]

Agree. The HRDX/V has become the SM57/8 of the amp world.

[@colinmortimore218]

@@GlennJimenez Hot Rod Devilles

[@GlennJimenez]

Ah yes, this model was my first tube amp. The dream started here. A nice affordable reliable tube combo, I genuinely loved mine. I remember I put 6V6 and a 12ay7 on mine.

[@mikiegood]

Fender used the 12AY7 “mod” in the George Benson HotRod Deluxe

[@Alejandro1956]

I am pretty sure is a 12AT7 in V1

[@johnwilliamson467]

5965 12av7 with more conductance is also a thought . the 12ay7 6072 sound very good in that amp. Going for a bit less gain than the 12ax7 is a fine choose in this amp and current market.

[@ctcards2636]

I own a 60watt version of this amp that use to be a 2x12 combo. I had a head cab made for it and ive had to do quite a lot of repairs on it over the years. Its now finally a reliable amp, i like running a 12AY7 in mine and a 12AT7 in the V3. I use one of those volume boxes to control the volume even more. These are not bad amps once the cheap parts have been replaced and a few mods were done. But still these amps just dont do it for the tone im looking for onstage. I only use mine at home these days to practice or do occasional recordings with. I was using a Twin reverb (also in a head cab) until late last year when I changed my setup to a SMS CTP preamp thru a ART power amp. After all the frustrations ive had with my Hot Rod, i would never buy another one. Occasionally I see used Twins in my area for not much more than a new Hot Rod, and the Twin is a much better sounding amp. Although the reissues have some of the same problems, but a friend of mine just got a nice 1974 Silver Face Twin for $750 with the original speakers and the amp got a good bill of health from a tech. So hes into that Twin for around $900. How much are these Hot Rods new ? LOL!

[@chrismosquad1056]

Great video! Good “in the room” sound. Thanks for posting. 👍🏻

[@lars-fenin]

the 12A7 in v1 is a good and relatively easy mod. ... opens up the amp nicely.

[@islanderwinder]

I tried this a few years ago with a JJ 5751 tube & the headroom was reduced when comparing it the the 12ax7 .I'm not convinced that a modern 12at or 12ay will give you more headroom .

[@musicmatty67]

For an amp that’s prone to circuitboard weaknesses… It sure sounds good.

[@roccocroce]

Prob a great tone for heading out to the highway

[@ebandcamp]

Did the ax7 mod it was great !

[@iplayloud2]

The 12ay7 has a gain factor of 45 versus 100x with a 12ax7 so if you use preamp gain things will change.

[@capitanvonchickenpants8492]

Better buy solid state for a backup

[@soapboxearth2]

i just bought a hr deville for 230 usd . making a LOT of 120 cycle hum and sounding quite strange... its a 2008 with original filter caps. no resister burns on the board.. i got it home and found that one power tube was bad. now the weird tone is gone and hum remains. i ordered filter caps for it. if that fixes the problem i intend to sell the working board and wire up a 5f6a/jmp on a turret board in the chassis . looks like it will need diode rectification but i am quite exited to get started. it will be my second amp build and hopefully turn out well...

[@MuscleDad420]

As soon as EHX dropped the news I think I spent over a grand in tubes just to make it through the next 4 months. Opted for all the Sovtek 5881WXT+ quads I could find at list price to use or break up into pairs because those things refuse to die. Bought a heap of JJ 12ax7's from CE, scrounged up Shuguang EL34B's under different badging, and some blue glass E34L's sitting in the darkest corners of the internet. If it drags on I have sources for dead stock Shuguangs in China, although I'd hate to open myself up to being buried in a backlog of work while sitting on my hands, waiting for those to cross the Pacific.

[@wadeguidry6675]

Can I put Sovtek 5881wxt in my 1978 Super Reverb(70watt, master volume)? It's supposed to have 6L6gc. I'm confused if they are interchangeable.

[@MuscleDad420]

@@wadeguidry6675 Yes. Sovtek and Groove Tubes have called it by many names (GT-6L6B, 6L6WGC, 5881WXT, 6L6WXT+, etc etc) but they’re all the same Russian Reflektor factory 6p3s-e tube and it is interchangeable with a 6L6GC. Expect to lose some overall output wattage unless you bias the amp on the hotter side. On most big Fender amps such as a Super Reverb you wouldn’t notice a difference. They’re loud enough as-is.

[@wadeguidry6675]

@@MuscleDad420 thanks. I have a set of matched 5881 tubes on my spare parts box. Just in case.

[@MuscleDad420]

@@wadeguidry6675 There’s a reason why you often find them stock in many new Fender amps. They can take a good beating from Johnny Skater every day after school at the local guitar shop. That and Fender tends to bias their amps cold from the factory. :)

[@Wi66pro]

Great video, very informative, thanks. Can you use wire wound aluminium case resisters 5W 470ohm for R78 & R79

[@PsionicAudio]

Thanks. Yes, if you chassis mount them.

[@TNTales]

Do you think issues with tube availability and quality should be a consideration when buying a tube amp now? Like are parts going to be come so less common that ownership and maintenance are cost prohibitive?

[@tedmich]

Yah, I got a matched quad of Mullard Reissue (Russian) EL84s in great time but my Slovak JJ 6L6 quad is taking FOREVER, go figure

[@andrewmccausland5440]

Could the same kind of gain reduction be done with the 12ax7 preamp tubes, by adding resistance in series with the V1a and b bypass caps (C1 and C56 on the HRD iii board)? Maybe even wire those PCB pads up to a dual gang pot and bypass capacitors for variable gain control? Great info on your videos - thanks!

[@PsionicAudio]

You don't want to change the bias that drastically. Look at the schematic. There is a resistor in series before the volume pot. If you want to reduce gain, that's where. But that involves mods. A 12AY7 is cheaper, faster, and non-permanent.

[@andrewmccausland5440]

However on second thought, if that were a JFET circuit then changing the JFET, even if it were the same type but especially if it were a different one, would likely change the bias and require a different resistor value at the source. I’m surprised changing the tube doesn’t require changing the resistor values to correct the bias - time to learn more about how tube preamp circuits work I guess 😁

[@camerond8176]

Do you need to re-bias the amp if I put a 12AY7 in V1 and a 12AT7 in V3 as it's only a rectifier tube?, keeping the 12AX7 in v2.

[@PsionicAudio]

None of those are rectifier tubes. Those are preamp tubes. But no, they won’t affect the bias.

[@camerond8176]

@@PsionicAudio - Thank you very much for confirming this. I wasn't sure and heard both yes and no.

[@DanielBobke]

I just got a set of 6L6s and 12AX7s but they were not cheap. It was about $150 for both sets (2 6L6 and 3 AX7). Wish I had seen this video - I may have bought the AY7s!

[@christophergaboury5930]

You only need the ay7 in the v1 spot. (All the way left). It’s a big improvement to my ears. Brings the point of breakup in the clean channel from 3.4/4 to about 7. Also makes the volume control way more useable.

[@oldguy5381]

Nice amp, tubes are getting short. And quickly I might add.

[@Curtislow2]

hello Lyle Any updates on your Psionic Excalibre ?

[@Curtislow2]

Sorry , Don't know how I Missed the Mar 21, 2022 update.

[@backlineguy]

you use the 12AY7 in the "V1" position?...I thought the V1 was the preamp tube closest to the Output tubes...no? I've used 12AT7's in THIS position and it seems to smooth out the Drive channel as well as reduce overall volume/output by maybe 35-40%...you think the 12AY7 cuts output by more than that? I'd definitely love to be able to have a bit of headroom on this thing too...great videos!

[@415TCrider]

v1 one is the first one on the far left of the amp rear.

[@kirkblatti5694]

V1 is closest to the input jack of the amp from the guitar. It's the first gain stage.

[@oscarm4154]

so in what possition did you install it of the 2

[@vl292]

Available amplification is reduced. How about the headroom? Is the maximum clean output increased? For that i think you need to up the power.

[@PsionicAudio]

No, doesn't change the maximum clean level. Just lets you have the low volume range the stock circuit lacks (stock 12AX7 goes from nothing to LOUD with almost no in-between). Cheap, easy, reversible "mod."

[@vdubguy7917]

@@PsionicAudio I put a 12at7 in v1 in my HRD 2, I liked it but ended up going back to AX7. I found that I would get some type of rattle when I played certain notes. Not sure if it was the tube. With the ax7 sounds like the rattle is gone. I now use the JHS black box and now I got more use of my volume knob. I do want to try the ay7 in v1, ax7 in v2 and at7 to see how it sounds. I also replaced stock speaker with the Creamback. Great amp. I really would like to fix the drive/more drive channel….

[@smartlevel1450]

Hello, I'm new to your channel. Really very informative stuff. I've seen some Hot Rods that mod the values of R9 and R44 do you have any idea for what is that mod?

[@PsionicAudio]

Thanks. Yeah, R9 affects the max possible level of the clean volume and R44 affects the taper. Both also affect the load and the high pass frequency, but they primarily affect gain/taper.

[@smartlevel1450]

@@PsionicAudio Thank you very much! You really know a lot about this. when you say the taper you refer to the taper of the Volume Pot?

[@PsionicAudio]

Yes. R9 is in series before the pot and R44 is parallel between the wiper and ground. Note that R44 affects the taper of the Gain pot on the OD channel too.

[@smartlevel1450]

@@PsionicAudio Thank you so so much for this explanation, couldn't find it in other place. Since I changed C1 and C56 from 47uF to 22 uF, V1 to 12AY7, V2 to 12 AU7, V3 to 12AT7 the sound of the amp improved a lot but have loss Gain or Volume or both. My amp has a R44 = 56K and R9= 270K. If I want to recover some of that Gain or Volume, how should I change this values? A really BIG thanks in advance from Venezuela. P.D: I use just the clean channel

[@smartlevel1450]

@@PsionicAudio Hello. Sorry if I overwhelm with a complicated question. But put it simple I would like to know if lowering the value of R9 (56K to 47K) will give me more gain or volume from the amp or backwards?

[@michaelshearer3559]

I forgot how dreadful the overdrive settings are on this amp.

[@MrAletube]

in reality,if you have a Celestion driver and a very nice sounding set of preamp tubes it can sound great,it's a condition that 99% of the users never experienced when trying it new,apart from the special editions,that said,there are better amps period

[@markleyva3108]

The drive channel is decent, it just sounds bad when the amp is eq’d for clean.

[@Earlvis]

Right!!!

[@blakejames9952]

I was told i should try a 12AT7 in v1 to help with the loudness volume. Any opinions or preferences between the 12AY7 and the 12AT7.?

[@PsionicAudio]

Yeah but I don’t have time to get into voltage vs current. AY is the better choice.

[@goldens98]

The 12at7 comes in the George Benson Hot Rod Deluxe.

[@Grant_Ferstat]

These amps are a backline nightmare to meas the stock volume taper is typically really frustrating. Too quiet to too loud in the tiniest knob increment.

[@corkystclair7475]

Luckily it's $10 to purchase an audio taper potentiometer, and an hour of work to replace it 😀

[@Grant_Ferstat]

@@corkystclair7475 unfortunately I’m talking about backline amps provided at venues and festivals :-)

[@PsionicAudio]

The HRD already has an audio taper volume pot.

[@mikehembree7973]

Get one of the lil boxes that run in the effects loop and that'll solve your volume problems on these.

[@waynegram8907]

You're using a 12AY7 for VI preamp tube? How do you get more headroom?

[@antonix_81]

12ay7 has less gain than a 12ax7 ,mu is 45 vs 100, you can try a 5751 too, something in between

[@waynegram8907]

@@antonix_81 yes I heard srv using 5751 tubes

[@antonix_81]

@@waynegram8907 yeh exactly! i used it sometimes on my jmp clone , and it does the job

[@luthiervandros]

If you want to spend $80 on a jj 12ax7, the tube store will oblige.